Browsing by study line "Genetik och genomik"
Now showing items 1-20 of 35
-
(2019)Glutamine, the conditionally essential amino acid, is a major carbon and nitrogen carrier required for a range of cell functions, such as protein synthesis and maintaining redox balance. While healthy cells adjust their activities in response to glutamine availability, tumor cells display deregulated glutamine uptake and metabolism allowing quick proliferation and survival in cellular stress conditions. Hence, further knowledge of the glutamine sensing network is of interest. Utilizing Drosophila melanogaster, the roles of formerly identified glutamine sensing regulator candidates, Forkhead box O (FoxO), Super sex combs (Sxc), Spalt major (Salm) and Spalt-related (Salr), were explored. Drosophila is an efficient model organism for analyzing gene regulatory mechanisms, with its simple genome but conserved genes and metabolic pathways. Loss-of function and gain-of-function mutants of the candidates were cultured with/without glutamine, and their physiological response and gene expression changes were analyzed. The results show the glutamine intolerant phenotype of FoxO and Sxc deficiency, not dependent on altered food intake levels of larvae. However, glutamine intolerance of Salr and Salm deficiency was not observed. Moreover, we aimed to gain further insight to the roles of FoxO and Sxc in glutamine metabolism. Since amino acid catabolism produces ammonia, and glutamine metabolism plays a vital role in ammonia detoxification, we performed a pH-based measurement of foxo and sxc mutant larvae hemolymph on food with/without glutamine. However, we could not associate FoxO or Sxc with regulation of glutamine-derived ammonia clearance. In addition, we explored FoxO downstream regulator candidates. Putative promoter areas of Paics, Uro, Sesn, salr, Prat2 and Gdh were cloned into reporter vectors and the luciferase activity was analyzed under the expression of foxo. The results indicate that FoxO is a regulator of all of the 6 genes. Next we could utilize the here constructed plasmids to see whether the FoxO-mediated regulation is affected by altered glutamine levels in cell culture.
-
(2019)In recent decades, ancient DNA recovered from old and degraded samples, such as bones and fossils, has presented novel prospects in the fields of genetics, archaeology and anthropology. In Finland, ancient DNA research is constrained by the poor preservation of bones: they are quickly degraded by acidic soils, limiting the age of DNA that can be recovered from physical remains. However, some soil components can bind DNA and thus protect the molecules from degradation. Ancient DNA from soils and sediments has previously been used to reconstruct paleoenvironments, to study ancient parasites and diet and to demonstrate the presence of a species at a given site, even when there are no visible fossils present. In this pilot study, I explored the potential of archaeological sediments as an alternative source of ancient human DNA. I collected sediment samples from five Finnish Neolithic Stone Age (6,000–4,000 years ago) settlement sites, located in woodland. In addition, I analysed a lakebed sample from a submerged Mesolithic (10,000–7,000 years ago) settlement site, and a soil sample from an Iron Age burial with bones present to compare DNA yields between the two materials. Soil samples were converted into Illumina sequencing libraries and enriched for human mtDNA. I analysed the sequencing data with a customised metagenomics-based bioinformatic analysis workflow. I also tested program performance with simulated data. The results suggested that human DNA preservation in Finnish archaeological sediments may be poor or very localised. I detected small amounts of human mtDNA in three Stone Age woodland settlement sites and a submerged Mesolithic settlement site. One Stone Age sample exhibited terminal damage patterns suggestive of DNA decay, but the time of deposition is difficult to estimate. Interestingly, no human DNA was recovered from the Iron Age burial soil, suggesting that body decomposition may not serve as a significant source of sedimentary ancient DNA. Additional complications may arise from the high inhibitor content of the soil and the abundance of microbial and other non-human DNA present in environmental samples. In the future, a more refined sampling approach, such as targeting microscopic bone fragments, could be a strategy worth trialling.
-
(2024)Cell-based immunotherapies offer highly targeted treatment, potentially leading to higher response rates and reduced long-term side effects compared to chemotherapy. In the clinics, chimeric antigen receptor T-cell therapies are already being used as neo-adjuvant therapy for certain types of cancer, however, they can have significant drawbacks. Natural killer (NK) cells have emerged as a promising alternative option for targeting various hematological and solid tumors. Unlike T-cells, NK-cells do not need prior sensitization to the target and have the potential to be used as a allogeneic, ‘Off-the-shelf’, product. Acute myeloid leukemia (AML) is the most common type of acute leukemia in adults. Chemotherapy and small molecule drugs are typically used for the treatment of AML. However, the prognosis for relapsed or refractory AML patients remains unsatisfactory. Therefore, a collaborative project between the Helsinki Central Hospital and the Advanced Cell Therapy Center from the Finnish Red Cross, Blood Service was initiated to develop clinical-NK products targeting high-risk AML patients in Finland. A reliable and suitable in vitro cytotoxicity assay was required to assess the efficacy of NK cells before they could be given to AML patients. A luminescence-based method utilizing cellular ATP, was found to be the best performing method considering constraints such as the limited amount of patient material. AML blasts were successfully isolated from the whole blood of patients using CD33 microbeads and maintained in a composition of cytokines mix in RPMI media. The cytotoxicity assay paired with statistical analysis was able to identify significant differences in cytotoxic efficacy between NK cells from different donors. Additionally, results indicate improved cytotoxic efficacy in activated NK cells compared to non-activated NK cells, highlighting the usefulness of activated NK cells for use in the clinics.
-
(2021)The Y chromosome has an essential role in the genetic sex determination in humans and other mammals. It contains a male-specific region (MSY) which escapes recombination and is inherited exclusively through the male line. The genetic variations inherited together on the MSY can be used in classifying Y chromosomes into haplogroups. Y-chromosomal haplogroups are highly informative of genetic ancestry, thus Y chromosomes have been widely used in tracing human population history. However, given the peculiar biology and analytical challenges specific to the Y chromosome, the chromosome is routinely excluded from genetic association studies. Consequently, potential impacts of Y-chromosomal variation on complex disease remain largely uncharacterized. Lately the access to large-scale biobank data has enabled to extend the Y-chromosomal genetic association studies. A recent UK Biobank study suggested links between Y-chromosomal haplogroup I1 and coronary artery disease (CAD) in the British population, but this result has not been validated in other datasets. Since Finland harbours a notable frequency of Y-chromosomal haplogroup I1, the relationship between haplogroup I1 and CAD can further be inferred in the Finnish population using data from the FinnGen project. The first aim of this thesis was to determine the prevalence of Y-chromosomal haplogroups in Finland and characterize their geographical distributions using genotyping array data from the FinnGen project. The second aim was to assess the role between Finnish Y-chromosomal haplogroups and coronary artery disease (CAD) by logistic regression. This thesis characterized the Y-chromosomal haplogroups in Finland for 24 160 males and evaluated the association between Y-chromosomal haplogroups and CAD in Finland. The dataset used in this study was extensive, providing an opportunity to study the Y-chromosomal variation geographically in Finland and its role in complex disease more accurately compared to previous studies. The geographical distribution of the Y-chromosomal haplogroups was characterized on 20 birth regions, and between eastern and western areas of Finland. Consistent with previous studies, the results demonstrated that two major Finnish Y-chromosomal haplogroup lineages, N1c1 and I1, displayed differing distributions within regions, especially between eastern and western Finland. Results from logistic regression analysis between CAD and Y-chromosomal haplogroups suggested no significant association between haplogroup I1 and CAD. Instead, the major Finnish Y-chromosomal haplogroup N1c1 displayed a decreased risk for CAD in the association analysis when compared against other haplogroups. Moreover, this thesis also demonstrated that the association results were not straightforwardly comparable between populations. For instance, haplogroup I1 displayed a decreased risk for CAD in the FinnGen dataset when compared against haplogroup R1b, whereas the same association was reported as risk increasing for CAD in the UK Biobank. Overall, this thesis demonstrates the possibility to study the genetics of Y chromosome using data from the FinnGen project, and highlights the value of including this part of the genome in the future complex disease studies.
-
(2024)Epigenetics is the study of changes in gene expression without alterations in the DNA sequence. Epigenetic modifications, of which DNA methylation (DNAm) is the most known, are crucial for many biological events, especially for normal development and genomic imprinting. In imprinted genes, only one of the parental alleles is consistently monoallelically expressed. The epigenome can be altered by various environmental factors such as diet and chemicals. Moreover, evidence indicates that assisted reproductive technology (ART) is associated with distinct DNAm patterns. Still, it is unclear whether these alterations are a consequence of ART procedures themselves or the underlying subfertility. This thesis aimed to study whether ART procedures and subfertility are associated with aberrant DNAm at the imprinted DLK1-DIO3 locus in the human placenta. The genes encoded from this paternally imprinted locus are essential in mammals' fetal and placental development. Moreover, recent evidence suggests that downregulation of the DLK1 gene is associated with ART and subfertility. Therefore, two gene regions, the IG-DMR and the DLK1 promoter, were chosen as study objects. The IG-DMR acts as the main regulator of gene expression at the whole DLK1-DIO3 locus, and promoter regions are considered important regulators of the expression of their corresponding genes. Eight ART, four subfertility, and six control samples of human placental DNA were studied. The subfertility group consisted of couples who were committed to initiating fertility treatments but eventually got pregnant spontaneously. The study was performed using traditional bisulfite sequencing, after which the differences in DNAm levels between study groups were statistically analyzed. As expected, significantly decreased DNAm level was observed in the placentas of subfertile couples compared to controls. Surprisingly, no significant differences were addressed between ART and control groups in either region. The partly unexpected results are explained by the fact that aberrant methylation at distinct imprinted DMRs, including the IG-DMR, is caused by the in vitro culture media. Moreover, the results indicate that the regulation of DLK1 expression is more complicated than that solely by the IG-DMR and the DLK1 promoter. Further research should be dedicated to differentiating the impacts of ART and subfertility on the epigenome and phenotype to better understand the health implications of ART.
-
(2020)Uterine leiomyomas are benign tumors originating in the smooth muscle cells of the uterine wall. Leiomyomas represent one of the most common tumor types in women affecting up to 80% of pre-menopausal women. Besides having extensive implications on women´s health through the numerous symptoms they cause, leiomyomas are a cause of remarkable financial burden worldwide. Bivalent promoters are defined by the co-occurrence of two histone modifications with opposite functions: trimethylation of lysine 4 on histone 3 (H3K4me3) and trimethylation of lysine 27 on histone 3 (H3K27me3). H3K4me3 is associated with promoters of actively expressed genes, whereas H3K27me3 is frequently found at promoters of silenced genes. The genes controlled by the bivalent promoters are reversibly silenced or expressed at low levels and remain poised for fast activation or full repression as a response to external cues. Bivalent chromatin is gaining more and more importance as new roles are identified in tumorigenesis and cell differentiation. Despite this, the vast majority of data available was obtained from cell lines, and not from human tissue. The aim of this thesis work was to map the genomic location of bivalent promoters in uterine leiomyoma and myometrium tissue, and to characterize the functions of bivalently-controlled genes in differentiated tissue. This would provide novel information about bivalent promoters’ distribution in human tissues and also their potential role in myomagenesis. Chromatin immunoprecipitation followed by sequencing (ChIP-seq) against H3K4me3 and H3K27me3 was performed on fresh frozen tissue samples of uterine leiomyomas and corresponding myometrium. A promoter was defined as bivalent, if it showed overlap between H3K4me3 and H3K27me3 peaks within a 2 kb region of a gene’s transcription start site in all samples. Altogether 951 bivalent promoters were found in myometrium and leiomyoma. Strikingly, only 231 (24.3%) promoters were present in both tissue types, most bivalent promoters being tissue-specific. These findings indicated bivalent promoters regulating a substantial number of genes also in differentiated tissue and the presence of extensive alterations in bivalent promoter distribution during myomagenesis. Gene ontology analyses of the bivalently-controlled genes in myometrium revealed the highest score for developmental processes. Instead, for leiomyomas, the highest enrichment was detected in stem cell fate specification-related processes. The data presented in this thesis suggests that bivalent chromatin plays an important role during myomagenesis, as it undergoes a significant reorganization during the process. Future experiments will provide novel insights about the role for these changes, i.e.: if they underlie the process.
-
(2024)The proper differentiation of cells in early human development is essential for the success of a pregnancy. The first cell-fate decision occurs when totipotent cells differentiate into inner cell mass and trophectoderm, forming a blastocyst. Trophoblast cells differentiate from the trophectoderm and form the placenta. Defects in trophoblast development can lead to several pathologies, such as preeclampsia, miscarriage and intrauterine growth restriction. TFAP2C is a gene that is known to have an important role in the differentiation of trophoblast, although its function is not completely understood. Recent studies have suggested that TFAP2C has a promoter that has not been previously annotated, and it is not yet known what functions different TFAP2C promoters have. The aim of this thesis is to characterise how the activation of this novel TFAP2C promoter or the consensus promoter affects TFAP2C expression and whether the activation of different promoters changes how human pluripotent stem cells differentiate. In addition, this thesis aims to detect whether different TFAP2C protein variants, which are produced by these promoters, explain the possible variation in differentiation. TFAP2C promoters were activated with CRISPR activation, and different TFAP2C variants were expressed as transgenes in pluripotent stem cells. Gene expression was studied with immunocytochemistry and quantitative reverse transcription PCR. The activation of the consensus promoter increased TFAP2C expression more than the activation of the novel promoter. However, activation of both and expression of the protein variants produced from them made cells differentiate into trophoblast-like cells and express trophoblast markers. Nonetheless, the novel promoter and protein variant seemed to differentiate cells into trophoblast more efficiently. Because the activation of the promoters and the expression of their corresponding protein variants led to similar results, it seems likely that the alteration in differentiation is caused by the different TFAP2C protein variants. The functional difference between variants might be affected by the presence of a SUMOylation motif in the wild-type TFAP2C. These results may help to better understand the role of TFAP2C in human embryonic development and create applications for assisted reproduction and infertility treatments, as well as facilitate the development of cell models that can be used in research and therapy.
-
(2020)Endometrial polyps are one of the most common benign uterine lesions, affecting approximately 10% of all adult women. While endometrial polyps have a high prevalence, their molecular pathogenesis and genetic background are largely undefined. Accordingly, the aim of this thesis was to characterize the somatic mutational landscape of endometrial polyps – to identify mutations in cancer-associated genes, and to identify mutational signatures contributing towards the somatic mutational spectrum. The present study was conducted using whole exome sequencing of 23 endometrial polyps and 18 matching normal blood samples. Mutational signature analysis was conducted using MutationalPatterns and SigProfiler. Endometrial polyps were found to carry varying number of somatic mutations in their exomes, most of them present at a low allelic fraction. Moreover, 43% (10/23) of the polyps were identified to carry one to four cancer-associated mutations, including mutations in genes such as PIK3CA 17% (4/23), KRAS 13% (3/23) and ERBB1 9% (2/23), which are well-established cancer driver genes. Cancer-associated mutational signatures do not have a notable contribution towards the somatic mutational spectrum of endometrial polyps. However, a novel signature, ‘signature B’, characterized by T>G mutations, was found to affect a subset of polyp samples. To conclude, the whole exome sequencing of endometrial polyps revealed several mutations in cancer-associated genes and a novel mutational signature, which may contribute to the development of these benign tumours. However, further research is required to confirm and validate the novel signature, and to define the genetic alterations leading to the polyp pathogenesis.
-
(2020)The human cerebral cortex is characteristically large and folded, which can be majorly attributed to the high number and variety of neural progenitors during embryonic development. Radial glial cells are essential neural progenitors during neurogenesis. In addition to giving rise to new cell types, they also provide scaffold for migrating newborn neurons. Radial glia are known to portray peculiar characteristics in their cell division process, including unique migratory behavior as well as specifically regulated cleavage furrow orientation. While these processes of radial glial division have been studied extensively, the underlying molecular mechanisms are still largely unknown. ABBA (actin-bundling protein with BAIAP2 homology) and NEDD9 (neural precursor cell expressed, developmentally downregulated 9) are proteins, which are both known to be expressed in certain radial glia progenitors during embryonic development, while they are mainly absent in neurons. ABBA has a defined role of regulating plasma membrane deformation and actin polymerization in radial glia, while NEDD9 expression levels are a known factor in the correct progression from mitosis to cytokinesis. An interaction between ABBA and NEDD9 has previously been identified in a yeast two-hybrid screen done for the embryonic mouse brain. The aim of this thesis was to validate the interaction between ABBA and NEDD9 biochemically. First, their interaction was evaluated by doing co-immunoprecipitation assays on the endogenous proteins from C6 cells. The second approach was to test, whether their interaction is directly mediated by the N-terminal SH3-domain of NEDD9 and the proline-rich C-terminal portion of ABBA. This was done by doing biochemical binding assays using purified proteins and domains of interest. While co-immunoprecipitation of the two proteins gave results indicating an interaction, I could show that there is no direct binding between NEDD9 SH3-domain and ABBA, suggesting that the interaction might require other domains or be indirect. Together, these results provide valuable information that will help characterize what roles of ABBA and NEDD9 play in cortical development and beyond.
-
(2021)Enhancers are important regulatory elements of DNA, that are bound by transcription factors (TFs) to regulate gene expression. Enhancers control cell type specific gene expression and they can form structures called super-enhancers, that consist of multiple normal enhancers and are bound by high numbers and variety of transcription factors. These super-enhancers are important for defining cell identity and changes in the super-enhancer landscape have been linked to different cancers. In this project, characterization of super-enhancers and their transcription factors composition between primary and cancer cells were studied using genome-wide next-generation sequencing data from multiple assays, such as ChIP-seq, RNA-seq and ATAC-seq. The focus of the project was on the data processing and analysis to identify and characterize the super-enhancers. Analyses included GSEA, heatmap binding analysis, peak and super-enhancer calling and IGV analysis. This project used pancreatic HPDE cell line for primary cells and different cancers with endodermal origin as cancer cell lines. The goal of the thesis was to try show characteristic features of super-enhancers and their features in normal and cancer cells. Data analysis showed that distinct super-enhancers can be identified in cancer cells and defined super-enhancers had typical strong binding for specific transcription factor and histone modification such as histone 3 lysine 27 acetylation (H3K27ac) mark of active enhancers. Super-enhancer regions were located in highly accessible chromatin regions of the genome, and genes that were associated with HPDE super-enhancers could be shown to have association with cell identity. Peak and super-enhancer calling counts varied between cell lines for transcription factors, histone modifications and super-enhancers. Visualization of super-enhancers was successful and could show transcription factor binding and active enhancers that establish the super-enhancer structure. Comprehensive analyses allowed us to characterize typical features of super-enhancers and show differences in the numbers of super-enhancers between primary and cancer cell lines and cancer cell lines of different organ types. Analysis of the transcription factor binding showed unique peaks on some of the super-enhancers, and these peaks might have a role in inducing the super-enhancer structure.
-
(2021)Uterine leiomyomas are benign smooth muscle tumors arising in myometrium. They are very common, and the incidence in women is up to 70% by the age of 50. Usually, leiomyomas are asymptomatic, but some patients suffer from various symptoms, including abnormal uterine bleeding, pelvic pain, urinary frequency, and constipation. Uterine leiomyomas may also cause subfertility. Genetic alterations in the known driver genes MED12, HMGA2, FH, and COL4A5-6 account for about 90 % of all leiomyomas. These initiator mutations result in distinct molecular subtypes of leiomyomas. The majority of whole-genome sequencing (WGS) studies analyzing chromosomal rearrangements have been performed using fresh frozen tissues. One aim of this study was to examine the feasibility of detecting chromosomal rearrangements from WGS data of formalin-fixed paraffin embedded (FFPE) tissue samples. Previous results from 3’RNA-sequencing data revealed a subset of uterine leiomyoma samples that displayed similar gene expression patterns with HMGA2-positive leiomyomas but were previously classified as HMGA2-negative by immunohistochemistry. According to 3’RNA-sequencing, all these tumors overexpressed PLAG1, and some of them overexpressed HMGA2 or HMGA1. Thus, the second aim of this study was to identify driver mutations in these leiomyoma samples using WGS. In this study, WGS was performed for 16 leiomyoma and 4 normal myometrium FFPE samples. The following bioinformatic tools were used to detect somatic alterations at multiple levels: Delly for chromosomal rearrangements, CNVkit for copy-number alterations, and Mutect for point mutations and small insertions and deletions. Sanger sequencing was used to validate findings. The quality of WGS data obtained from FFPE samples was sufficient for detecting chromosomal rearrangements, although the number of calls were quite high. We identified recurrent chromosomal rearrangements affecting HMGA2, HMGA1, and PLAG1, mutually exclusively. One sample did not harbor any of these rearrangements, but a deletion in COL4A5-6 was found. Biallelic loss of DEPDC5 was seen in one sample with an HMGA2 rearrangement and in another sample with an HMGA1 rearrangement. HMGA2 and HMGA1 encode architectural chromatin proteins regulating several transcription factors. It is well-known that HMGA2 upregulates PLAG1 expression. The structure and functionality of HMGA2 and HMGA1 are very similar and conserved, so it might be that HMGA1 may also regulate PLAG1 expression. The results of this study suggest that HMGA2 and HMGA1 drive tumorigenesis by regulating PLAG1, and thus, PLAG1 rearrangements resulting in PLAG1 overexpression can also drive tumorigenesis. A few samples, previously classified as HMGA2-negative by immunohistochemistry, revealed to harbor HMGA2 rearrangements, suggesting that the proportion of HMGA2-positive leiomyomas might be underestimated in previous studies using immunohistochemistry. Only one study has previously reported biallelic inactivation of DEPDC5 in leiomyomas, and the results of this study support the idea that biallelic loss of DEPDC5 is a secondary driver event in uterine leiomyomas.
-
(2020)Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited autosomal dominant disease that leads to cognitive impairment, vascular dementia and ischemic strokes. In CADASIL, vascular smooth muscle cells (VSMCs) degrade gradually and are replaced by connective tissue in the small and mid-sized arteries in the brain. Extracellular granular osmiophilic material (GOM) that surround the VSMCs are a unique feature in CADASIL. The causal gene behind CADASIL is Notch3, which encodes a transmembrane protein with a signaling function. There are over 200 cysteine-altering mutations that cause CADASIL in Notch3. The potential pathology causing mechanism is still unclear, but most likely the mechanism is linked to the aggregation of GOM deposits that are potentially toxic to VSMCs. This thesis project aimed to correct CADASIL causing c.475C>T mutation in Notch3 in different CADASIL cell lines with different CRISPR base editor systems. Another aim was to create induced pluripotent stem cell (iPSC) lines from a CADASIL patient-derived skin biopsy sample to be used in the creation of an in vitro disease model for CADASIL. RNA-based ABEmax base editor system was used to correct immortalized- and primary- CADASIL cell lines. DNA-based ABEmax base editor system was used as a positive control. Simultaneous pluripotent reprogramming and pathogenic CADASIL mutation correction were done in the same transfection during this project. The editing efficiencies were evaluated by Sanger sequencing the genomic target region before and after the transfection. The editing efficiencies were good in general compared to literature. They ranged from 27 % to 73 % target base editing efficiency depending on the editing system-, guide-RNAs - and electroporation parameters used. Confirmed proximal off-target effects were not detected, and distal off-target effects were not evaluated.
-
(2024)ASH1L is a Histone lysine methyltransferase belonging to the KMT family, which plays an important role in epigenetic gene regulation during development, and has been linked to neurodevelopmental disorders (NDDs). Mutations in ASH1L have been linked to NDDs including intellectual disability, autism spectrum disorder and Tourette’s syndrome. Induced pluripotent stem cell (iPSC) based models in combination with CRISPR/Cas9 gene editing provide powerful tools for studying the genetic causes of NDDs. The broad aim of this thesis was the creation of genetically modified iPSC lines for modelling NDDs linked to ASH1L. Patient and healthy cell lines were obtained from the Northern Finland Intellectual Disability cohort. With the long-term goal of generating a model by which to understand the impact of genetic background on reported causative mutations, CRISPR/Cas9-based genetic engineering was employed to correct the mutation in a patient cell line, and conversely, to generate a patient mutation in a healthy line. iPSC lines are known to be intrinsically variable and require thorough characterization of their genetic stability and pluripotency before use. Therefore, the secondary aim of this thesis was to subject newly reprogrammed iPSC lines to a battery of assays to first determine their suitability for downstream applications. Single-guide RNAs (sgRNAs) were designed to target a site ≤16 bp from the edit site. Single-stranded oligodeoxynucleotides (ssODNs) were used as HDR templates, incorporating the mutation of interest and 3-4 silent mutations to prevent binding by sgRNA after successful HDR. The Cas9-sgRNA complex and HDR template were introduced into the cell by nucleofection. Both mutations are frameshift mutations and are predicted to cause loss of function. Editing efficiency was evaluated with a T7E1 assay after nucleofection. Individual clones were isolated and MiSeq was used to sequence the region to a read depth of >1000reads per clone around the edit site to identify successful edits in these clones that can be used in downstream NDD modelling applications. Edit efficiencies were found to vary between sgRNAs and cell lines. In the correction attempts, guides were found to be almost entirely ineffective, producing only a single successfully edited clone among the combined 192 isolated clones. In the knock-in lines, both guides were effective at producing edited clones. The knock-in guide with the highest predicted efficiency and the shortest edit distance predictably produced the highest number of edits, but also a higher number of homozygotic knock-ins.
-
(2024)Drought events will increase in the future due to climate change and thereby threaten agricultural production. The growing world population needs stable yields nonetheless thus, solutions need to be found. One way to do so is to explore mechanisms that allow plants to withstand harsh conditions and recover from them. Autophagy is such a mechanism. It is a bulk degradation pathwaythat allows plants to recycle cell components. During biotic and abiotic stress autophagy pathways are enhanced. Even though this mechanism is very useful and is proven to enhance abiotic stress tolerance, very little is known about it in plants. This thesis aimed at defining the informative time points for drought and autophagy response during drought and recovery in barley. To do so barley plants were subjected to gradual drought by withholding irrigation. They were kept at a level of severe drought for 4 days and were then rewatered. The tip of the third leaf was sampled for RNA extraction followed by qPCR. The genes this thesis focused on were GST and HSP17 as indicators of drought stress and ATG6 as indicator for autophagy. Additionally, phenotypic data was collected via RGB imaging for monitoring wilting and thermal imaging for stomata closure. GST was upregulated during the onset of drought, which seems to make it an early response gene, while HSP17 was upregulated during severe drought. ATG6 had a high transcription rate during all stages of drought and only decreased during recovery. However, because the primer efficiencies calculated in this experiment appear to be very low, and data points were missing due to pipetting practice, the results are not reliable and need to be repeated. Thus, no prediction about the informative time points can be made. The thermal data showed good results and the expected pattern of stomatal closing during drought could be observed. But because the greenhouse is a variable environment a reference would make the data even more precise.
-
(2019)Background- Colorectal cancer (CRC) is the third most common epithelial carcinoma. There is an increased risk of colorectal cancer in people with longstanding inflammation in the large intestine, including individuals with ulcerative colitis (UC). Epigenetic changes in CRC such as aberrant DNA methylation alterations are common changes in human cancer. The aim of this study is to identify the DNA methylation alterations of selected inflammation related genes in UC-CRC vs. Lynch syndrome (LS). Method- DNA was extracted from archival tissue specimens from normal and tumor samples from UC-CRC (n= 31), and LS-CRC (n=29). Methylation-specific multiple ligation-dependent probe amplification (MS-MLPA) assays were used to detect CIMP status and CpG promoter methylation status of seven inflammation related genes. Microsatellite instability analysis was carried out using two mononucleotide repeat markers BAT25 and BAT26. Results- Increased hypermethylation frequencies in carcinoma vs. normal colonic mucosa were detected for all the inflammatory marker genes in specimens of UC-CRC patients. Statistically significant differences for methylation frequencies were observed in the NTSR1 gene (p value =0.008) and SOCS2 gene (p value =0.04) in specimens of UC-CRC patients. NTSR1 gene showed significantly increased methylation of normal colonic mucosae from UC-CRC vs. LS patients (p value=0.01). Conclusion- UC-CRC and LS tumor specimens revealed varying frequencies of hypermethylation in all the inflammatory genes. Methylation of the NTSR1 in the normal colonic mucosa suggests a possible field defect in UC-CRC, and could thus be used as an early biomarker to detect increased UC-CRC risk in non-neoplastic epithelium.
-
(2020)Multiple myeloma (MM) is a heterogeneous plasma cell cancer that results from the excessive proliferation of mutated B cells in the bone marrow and the accumulation of ineffective antibodies, monoclonal proteins, in the blood. Despite recent advances in research and novel therapeutics, MM remains incurable, mainly due to the mechanisms underlying disease progression and drug resistance. Therefore, novel biomarkers and therapeutics for the treatment of relapsed and refractory MM are urgently needed. MicroRNAs (miRNAs), short non-coding RNA molecules that play a key role in post-transcriptional gene regulation, have been found to be associated with different hallmarks of MM. Previous studies have indicated that abnormally functioning miRNA-mediated gene regulation followed by oncogene activation and tumor suppressor gene silencing results in drastic alterations in cell proliferation, apoptosis, growth, and metabolism. These changes in cellular functions have been indicated to be associated with the pathogenesis, progression, and formation of drug resistance in MM. Therefore, the role and potential of miRNAs to act as biomarkers to predict MM progression and drug sensitivity should be further investigated to ultimately improve the survival rates of patients. The aim of this master’s thesis was to investigate the relationships between drug sensitivity, disease progression and miRNA regulation in MM patients. Bioinformatically predicted miRNAs identified to be associated with sensitivity to panobinostat, a novel histone deacetylase inhibitor, and MM progression were validated in MM patient samples by using real-time quantitative reverse transcription PCR (RT-qPCR). In addition, the specific gene targets of miRNAs involved in the regulation of drug responses and MM progression were predicted by identifying statistically significant, negatively correlated interactions between the miRNA and RNA sequencing data of 45 MM patients in pairwise comparative correlation analysis. Finally, the predicted miRNA targets genes were validated in MM patient samples using RT-qPCR. Based on the bioinformatic analyses and RT-qPCR validation, mir-424 expression was significantly increased in relapsed MM patients as compared to respective patient samples taken at diagnosis, suggesting a potential role of mir-424 in MM progression. Similarly, mir-4433b expression was significantly elevated in panobinostat-resistant patients compared to sensitive patients, suggesting a potential effect of mir-4433b on the regulation of panobinostat drug response in MM patients. In addition, the RT-qPCR validation demonstrated that the disease progression and drug sensitivity associated mir-92b, mir-363 and mir-221, would potentially regulate the expression of FGF2, MFF, and TMEM248, respectively, providing novel insights into the functional roles of miRNAs in MM pathways.
-
(2020)Leaf senescence is a developmental and physiological phase in plants to end leaf development. Environment factors such as drought stress, extreme temperature, and pathogen threat and internal factors including age and reactive oxygen species induce leaf senescence. Some phytohormones such as jasmonic acid and salicylic acid play a key function in cell death in plants. WRKY transcription factors is known as one of the largest transcription factor family in plants which regulates a variety of plants processes. WRKY75 which belong to WRKY transcription factors has shown multiple functions in plant development like regulation of Pi starvation responses and root development and flowering. In my thesis, I focused on the role of WRKY75 in senescence and stress responses. WRKY75 was identified as a positive regulator of cell death in Arabidopsis. WRKY75 can promote salicylic acid biosynthesis by promote transcript levels of SID2 and also cause hydrogen peroxide accumulation by suppressing the transcription of CAT2. Hydrogen peroxide and salicylic acid can promote WRKY75 transcription at the same time. To evaluate the function of WRKY75 transcription factor in SA signalling and cell death, three lesion mimic mutants acd5, cat2, dnd1 and their corresponding wrky75 double mutant were used. Interestingly, no different phenotypes were found between acd5, cat2, dnd1 and their corresponding wrky75 double mutants in cell death and hydrogen peroxide accumulation detection in Arabidopsis leaves. Meanwhile, marker genes transcription levels were not different in both short day and long day growth condition. However, different phenotypes were observed in botrytis infection. Based on these results, we formed a hypothesis that gene redundancy could influence genetic characterization of WRKY75. To overcome this problem, SRDX-WRKY75 chimeric repressor transgenic lines were generated. The SRDX domain act as a dominant negative regulator to suppress WRKY75 target genes. In future research, these new lines can be used to test transcript levels for putative WRKY75 target genes.
-
(2021)The European rabbit (Oryctolagus cuniculus) is a small mammal native to the Iberian Peninsula, but introduced by humans to all continents except Antarctica. The rabbit has been a remarkably successful invasive species due to its generalist nature and fast reproduction. Its spreading has mostly been destructive to the local nature, and humans have used fatal rabbit diseases such as rabbit haemorrhagic disease (RHD) to control harmful populations. The rabbit population in Helsinki is one of the most northern annually surviving rabbit populations in the world. It is believed to have originated from escaped pet rabbits in the late 1980s, and in the early 2000s, the rabbits spread rapidly around the Helsinki area. RHD spread unintentionally to Finland in 2016, and the disease caused a significant reduction in the Helsinki rabbit population. Rabbit population genetics has previously been studied in several countries, but never before in Finland. The aim of the thesis was to examine the genetic diversity and population structure of the Helsinki rabbit population before and after the RHD epidemic, and to compare the results to similar preceding rabbit population genetic studies. Rabbit populations have previously been found to recover from major population crashes without a notable loss in genetic diversity using DNA microsatellite markers. The recent RHD epidemic in Helsinki provided an opportunity to study, whether a rabbit population can recover from a population crash even in a harsher environment without losing genetic diversity. To conduct genetic analysis, fourteen DNA microsatellite loci were genotyped from individuals caught during two distinct time periods, in 2008-2009 (n=130) and in 2019-2020 (n=59). Population structure was observed in both temporal rabbit populations with small but significant FST values. The 2019-2020 population was more diverse than the 2008-2009 population in terms of allele numbers and expected heterozygosity. This result was unexpected considering the recent RHD-epidemic but could be explained by gene flow from new escaped rabbits. Compared to other wild rabbit populations around the world, the Helsinki area rabbits exhibit significantly lower genetic diversity. Bottleneck tests showed a significant signal separately in both temporal populations, but the RHD bottleneck cannot be distinguished based on the tests. The results could be biased by new gene flow, or the initial bottleneck caused by the founder effect of only a few pet rabbits. The rabbits have demonstrated their adaptation and survival skills in the cold climate of Helsinki. The population has significantly lower genetic diversity compared to other wild populations, yet recovered from a major RHD epidemic without reduction in genetic diversity under these more extreme environmental conditions. It has been proven again; the rabbit is a thriving invasive species.
-
(2019)Preeclampsia is a vascular pregnancy disorder characterized by new-onset hypertension and proteinuria and/or new-onset preeclampsia associated symptoms during the second half of pregnancy. The pathophysiology of the disorder is not fully understood, but incomplete placentation and maternal tolerance towards fetal tissue are known to play a part in the disease pathogenesis. Predisposing factors include nulliparity, obesity, diabetes, chronic hypertension and autoimmune diseases. Furthermore, women who have experienced preeclampsia are more susceptible to cardiovascular disease later in life. One established biomarker for preeclampsia is the increased concentration of the soluble Fms-like tyrosine kinase 1 (sFlt1) in the maternal serum. sFlt1 is frequently overexpressed in preeclampsia and it is linked with angiogenic imbalance and endothelial dysfunction, although its role in the disorder is not completely clear. Preeclampsia has a genetic background. There are protective and predisposing variants in and near the Fms related tyrosine kinase 1 gene (FLT1; coding for sFlt1) that have been associated with preeclampsia either in the mother or in the fetus. In this study, five genetic polymorphisms over a 2.3 kb region in the 3’ untranslated region of FLT1 were genotyped by Sanger sequencing and fragment analysis in altogether 1200 individuals consisting of case and control mother–child pairs of the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort. These polymorphisms were tested for association with various preeclampsia-related phenotypes by Fisher’s exact test. In the maternal genome, the minor alleles of rs17086497 and rs57760154 were associated with extreme hypertension (systolic blood pressure >180 mmHg) (p=0.004, OR=1.77) and obesity (p=0.023, OR=1.63). Homozygosity for these minor alleles was associated with pregnancy complications in general (p=0.026, OR=2.53) and the early-onset form of preeclampsia (p=0.004, OR=3.34). Additionally, the minor alleles of rs9554314, rs3138582 and rs149279513 were associated with extreme hypertension (p=0.045, OR=1.63) and obesity (p=0.023, OR=1.78). Moreover, a suggestive association to severe proteinuria (> 5 g/24h) was found in the maternal genome. In the fetal genome, significant negative associations were reached for rs17086497 and rs57760154 in terms of the serum concentration of sFlt1 in the preeclampsia group (p=0.008, OR=0.23). Overall, the results seem to link the studied region in the maternal genome to preeclampsia with severe features. This supports the idea of preeclampsia as a heterogeneous disorder with varying etiology and mechanisms and thus highlights the importance of differentiating between the various sub-phenotypes. For example, the association of the same allele in the fetal genome with lower maternal sFlt1 levels and in the maternal genome with severe symptoms of preeclampsia suggests that the sFlt1 level might not be a good measure in all patients. Additionally, the observed associations with extreme hypertension and obesity point to the possibility that this region might be relevant for the endothelial damage that is thought to be a central factor in creating the later-in-life disease susceptibility.
-
(2024)Silver birch (Betula pendula) is both the third most commercially important, as well as abundant, tree in Finland. Faster growth is of interest from an industry, as well as climate change, perspective. In addition to higher biomass yield from a commercial point of view, faster growth in trees leads to absorption of more carbon dioxide, thus increasing their effect as a carbon sink to lessen the impact of climate change. By conducting a genome-wide association study, the aim of this thesis was to investigate the genetical background of B. pendula on three first-year growth traits: maximum height, maximum growth rate and time to cessation. Whole-genome sequencing data from 405 mother trees was used to provide a high-resolution genome-wide map for assessing genes associated with the three growth traits. A high-quality genotypic dataset of 5,727,473 single-nucleotide polymorphisms (SNP), which span across the whole genome, was established through rigorous filtering. Phenotypic data was estimated with a mixed linear model by best linear unbiased prediction from mother trees’ 7,266 seedlings, which were grown in a greenhouse under controlled conditions to monitor their height trajectories. Association testing was done as both a uni- and multivariate mixed linear model with the GEMMA algorithm. Overall, 16 unique suggestively significant SNPs were discovered among the three traits. Genes putatively associated with the SNPs were related to metabolic regulation and cell transportation processes, as well as biotic and abiotic stress. On each of the three traits, SNPs with the largest effects had around 5% deviation against the average phenotypic value, which could be considered a major effect for a polygenic trait. Only 4 out of the 16 suggestively associated SNPs were within gene regions, even though the putative genes themselves had also variants present abundantly in the dataset. This could suggest that the associated SNPs could be related to gene expression regulation, or they could be in linkage disequilibrium with multiple different genes, and thus be markers for combined effects of multiple genes on the focal trait. To validate the results, further studies such as gene editing on the associated genes, or a duplicated study on a different population, would be needed.
Now showing items 1-20 of 35