Browsing by study line "Genetics and genomics"

Intestinal stem cells maintain the regenerative potential of intestinal epithelium, which needs to be renewed constantly. Dysregulation of intestinal stem cell proliferation is associated with aging and intestinal diseases. The midgut of Drosophila melanogaster is a valuable model for studying intestinal stem cell driven tissue regeneration. It is similar in function to the mammalian small intestine but has a simpler cellular structure. Drosophila midgut is divided into five major regions with specialized physiological functions, characteristic morphological features and distinctive gene expression profiles. The midgut consists of a monolayer of absorptive enterocytes, small secreting enteroendocrine cells, intestinal stem cells and enteroblasts. Intestinal stem cells differentiate into enterocytes through a transient enteroblast phase. 5-hydroxytryptamine has been shown to activate proliferation of intestinal epithelium in mammals, but its mechanism of action is still unknown. Also, sex-specific differences in 5-hydroxytryptamine signalling have been recorded in mammals. 5-hydroxytryptamine signalling pathway has several downstream targets that have diverse downstream effect. Thus, 5-hydroxytryptamine signalling creates a complex and versatile regulatory network. The aim of my thesis is to study the effects of 5-hydroxytryptamine signalling on intestinal stem cell proliferation and cellular turnover in Drosophila midgut in both sexes. The effects of excessive amounts of 5-hydroxytryptamine are first studied by feeding Drosophila with 5-hydroxytryptophan, a product of the rate-limiting step in the 5-hydroxytryptamine synthesis pathway. The effects of 5-hydroxytryptamine signalling are further studied by knocking down and overexpressing a component of the 5-hydroxytryptamine signalling pathway in intestinal stem cells and enteroblasts. Dissected midguts are immunofluorescently stained, imaged and analysed both visually and with bioinformatics tools. The results indicate that 5-hydroxytryptamine signalling has both regional and sex-specific functions that affect intestinal stem cell proliferation and cellular turnover in Drosophila midgut. The most dramatic effects are seen in cellular turnover, which indicates that 5-hydroxytryptamine signalling plays a role in enteroblast differentiation. Furthermore, the results suggest that bidirectional signalling between enteroblasts and dying enterocytes facilitates cellular turnover in the midgut. As 5-hydroxytryptamine signalling is indicated in inflammatory bowel diseases such as Crohn’s disease, my results might help in the development of treatments for such conditions.

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.

Human induced pluripotent stem cells (hiPSCs) are derived from adult differentiated somatic cells and reprogrammed to an embryonic-like state. Pluripotent stem cells can be differentiated into almost any somatic cell type by using directed differentiation methods, but the differentiation efficiency often varies depending on the cell type. hiPSCs and cells differentiated from them can be used as a disease model carrying the patient’s phenotype and genotype. Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease where both upper and lower motor neurons degenerate, leading to paralysis. There is no curative treatment for ALS, and it leads to the death of the patient in 3 to 5 years on average from the first symptoms. The most common genetic cause of familial ALS is a hexanucleotide repeat expansion in C9orf72-gene. ALS pathology is strongly linked to endoplasmic reticulum (ER) stress, which affects cell homeostasis and proteostasis, and leads to apoptosis when prolonged. The primary aim of this research is to characterize the differentiation of four hiPSCs lines towards lower motor neurons and to study the neuroprotective effects of cerebral dopamine neurotrophic factor (CDNF) and CDNF-derived peptide on ER stress and cell viability. This experiment used two control cell lines from two healthy donors and two patient cell lines from two different ALS patients carrying the C9orf72-mutation. To evaluate the efficiency of the differentiation towards motor neurons, molecular markers for pluripotent and neural progenitor cells as well as for maturated motor neurons were analyzed. Relative gene expression levels were measured from weekly time points with qPCR. Immunocytochemical (ICC) antibody staining was performed during differentiation. Endogenic CDNF levels were analyzed from differentiating cells at weekly time points and the effect of CDNF on Thapsigargin (TG) -induced ER stress in motor neurons was analyzed. In addition, cell viability was analyzed in TG-CDNF treatment. All pluripotent and progenitor markers were downregulated in differentiated cells, and the expression of the mature motor neuron markers was upregulated. Mature motor neuron markers were also expressed at the protein level. The endogenous CDNF levels were highest at the progenitor cell stage. The ER stress response was upregulated in TG-treated cells, and there were no differences between treatments against ER stress. Furthermore, TG and growth factor treatments differentially affected the viability of the control and patient cell lines. Treatment decreased viability in control cell lines and increased viability in patient cell lines. Pluripotent stem cells were successfully differentiated toward motor neurons. The differentiation was performed twice, and the results were similar on both individual biological repeats. Analysis of endogenous CDNF expression levels was performed for the first time on hiPSCs lines. In this study, CDNF or its derivate didn’t reduce ER stress but it influenced cell viability, especially in patient cell lines with growth factor treatment. In the future, TG-treatment could be optimized regarding timing and growth factor treatment, or the toxin could be changed to another ER-stress inducing toxin. In addition, the C9orf72 pathology should be identified in order to use differentiated motor neurons as a pre-clinical disease model.

The field of gene technology, which falls under the umbrella of biotechnology, presents challenges in business development and commercialisation. Understanding the field characteristics is crucial for successful commercialisation, as it can significantly impact the available strategies for bringing products or services to market, ultimately shaping the business model. This study aims to investigate and understand the challenges associated with commercializing gene technology, including identifying any typical challenge profiles specific to the field and possibly arising from the biological material. The research involves semi-structured interviews with multiple companies, venture capitals, and experts in the field to gain a comprehensive understanding of the challenges. The collected data is then analysed to identify common characteristics and business practices against a commercialisation model frame. The motivation behind this study is to provide researchers and other stakeholders with insights into the challenges they may face while commercializing gene technologies, with the aim of lowering the threshold for business creation. The findings reveal that there are two major groups of companies, each with their specific challenges. The challenges for the major group revolve around business know-how, HR, and sales, while the minor group faces challenges related to technology and regulation. However, a common theme is the limited market awareness among customers, which requires significant efforts in sales, marketing, and communications. The study provides guidance to company founders on the different challenges they should be prepared for and offers insights to society on how to harness the value of gene technologies.

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.

MLH1 is a gene that codes for one of the four mismatch repair (MMR) proteins alongside MSH2, MSH6, and PMS2. The main function of the MMR proteins is to recognize base mismatches and insertion-deletion loops formed during DNA replication and aid in their excision. Inherited heterozygous pathogenic variants in any of the four MMR genes lead to Lynch syndrome, an inherited cancer syndrome that predisposes to multiple different cancer types, most notably colorectal cancer. Loss of the expression of an MMR gene causes MMR-deficiency, which leads to microsatellite instability, the accumulation of mutations in microsatellite regions of the DNA. The higher mutational burden caused by MMR-deficiency is thought to be the main driving force of genomic instability and tumorigenesis in MMR-deficient cells. In addition to MMR, MLH1 and the MMR machinery have roles in other anticarcinogenic cellular processes, such as DNA damage signaling and DNA double-strand break repair. Recently, MLH1 has also been shown to have a significant role in regulating mitochondrial metabolism and oxidative stress responses. The identification of MMR-proficient tumors in Lynch syndrome patients begs the question whether the lower amount of functional MLH1 observed in MLH1 mutation carriers could cause problems with these functions and pose alternative routes to tumorigenesis. In line with this, it has been shown that the role of MLH1 in cell cycle regulation in DNA damage signaling is notably more sensitive to decreased amount of the protein compared to its role in MMR. The main goal of the thesis was to study the effects of decreased MLH1 expression on gene expression, cellular functions, and possible alternative tumorigenic pathways. In order to achieve this, the coding transcriptome of human fibroblast cell lines expressing MLH1 at different levels was sequenced and the resulting data analyzed. The study revealed that decreased MLH1 expression affects cellular functions associated with mitochondrial function and oxidative stress responses in cells with functional MMR. Particularly NRF2-controlled cytoprotective defence systems were observed to be downregulated. Decreased MLH1 expression was also observed to affect several cellular functions associated with reorganization of the cytoskeleton and interactions with the extracellular matrix. These results strengthen the recently made notions that MLH1 has a role in controlling the function of mitochondria and in mitigating oxidative stress, and that these two functions are connected. The study also brings to light new information on the possible role of MLH1 in controlling the organization of the cytoskeleton, which has previously received little attention. Dysfunction of mitochondria, increased oxidative stress, and reorganization of the cytoskeleton, as a result of decreased MLH1 expression, could pose events that facilitate malignant transformation of cells prior to the total loss of MMR function.

The RNA splicing process is an important part of gene expression in which the introns are removed from the pre-mRNA so that the mature mRNA only contains protein coding exons. The splicing process is executed by the spliceosome in two subsequent transesterification reactions that occur partly co-transcriptionally. In the first step an intron lariat is formed between the exons. This is followed by splicing of the intron lariat and ligating the exons together. Genetic variants that affect the splicing of a particular gene are called splicing variants and they may disrupt the normal splicing process. Splicing variants can be both exonic or intronic and have effects on splice site recognition, activate cryptic splice sites or create new splice sites. These changes can lead to for example exon skipping or intron retention in the transcript. Diagnosing splicing variants is challenging because of the unknown functional effects of the variants. Splicing prediction tools can help predict the possible effects of variants. Different sequencing methods enable the detection of aberrant splicing transcripts and thus may help in variant interpretation. The aim of this master’s thesis was to develop a detection method suitable for the diagnostic laboratory for RNA splicing variants in congenital disorders. The methods that were tested included RNA and Sanger sequencing. First, the patient selection was performed using splicing predictions and previous research on the variants. Secondly, after receiving patient samples, RNA was extracted, and its integrity measured. The laboratory work was then divided into two parts, the other leading to the RNA sequencing and the other to Sanger sequencing. Before Sanger sequencing primer design, RT-PCR, PCR and analysis of the PCR fragment sizes was performed. RNA sequencing was preceded by RNA library preparation. The studied variants in this thesis were BRCA2 c.476-3C>A, MSH2 c.2005+3A>T and CYLD c.2350+5G>A. The PCR fragment analysis and Sanger sequencing was able to detect an aberrant splicing transcript with exon skipping on two patients caused by a variant in the CYLD gene. The RNA sequencing results confirmed the aberrant splicing transcript. In addition, fragment analysis showed evidence of a possible splicing isoform with skipping of two exons caused by a variant in the BRCA2 gene that was not expressed enough to show on the Sanger sequencing results. The RNA sequencing detected a splicing transcript with exon skipping in two BRCA2 patients. However, this was not the same transcript as interpreted from the fragment analysis results and no results in the RNA sequencing indicated a transcript with skipping of two exons.

Kv7.1 is a potassium ion channel comprised of the KCNQ1 protein, which can coassemble with distinct β-subunits modulating the channel functions in different tissues. In 2017, Raivio’s group (from the University of Helsinki) found two missense mutations in the KCNQ1 gene, p.(Arg116Leu) and p.(Pro369Leu), responsible for causing pituitary hormone deficiency and maternally inherited gingival fibromatosis. The facial features and bone structure pointed to a cranial neural crest (CNC)-derived phenotype caused by an alteration in the potassium channel balance, given that these cells form the bone and cartilage of the cranial zone. To understand the implication of the CNC in the KCNQ1 syndrome, I attempted to replicate the CNC differentiation protocol of Suga and Furue (2019) with the aim of obtaining cranial neural crest cells (CNCCs). This would enable future generation of a KCNQ1-related disease model. The differentiation process was carried out thrice, and two BMP4 concentrations (10 and 100 ng/ml) were assayed. The differentiated cells exhibited a CNC-like morphology as well as upregulation of the marker genes (TFAP2A, SOX10, DLX1, MSX1, and DLX2) associated to this cell lineage. However, the gene expression was low according to the qRT-PCR Ct values, which were in most cases higher than 30. Additionally, no differences were found between the two BMP4 treatments. Furthermore, the cells did not express KCNQ1, and thus the impact of the two KCNQ1 mutations was not investigated under this protocol. In conclusion, the protocol had a low efficiency in the generation of CNCCs that was not improved by increasing the BMP4 concentration. Further optimization of the protocol, such as the BMP4 concentration or the cell density of the culture, will be needed to improve its efficiency and obtain an adequate disease model.

The intestinal stem cells (ISCs) adapt in response to environmental factors and continually proliferate to renew the mammalian intestinal epithelium due to its rapid turnover. Overall, intestinal homeostasis is maintained by the differentiation and self-renewal of ISCs, which are regulated by different mechanisms, including epigenetic histone modifications. Earlier studies in the host laboratory have shown that the histone methyltransferase Su(var)3-9 is essential in the nutrient-induced activation of intestinal stem cells. Su(var)3-9 specifically trimethylates histone H3 on lysine 9 (H3K9me3), which is a repressive histone mark, responsible for transcriptional silencing at heterochromatin regions. It influences stem cell maturation, lineage specification, and many other cellular processes. However, the precise mechanisms behind its function in ISCs remain unknown – that knowledge is important for understanding the development of many diseases, including cancer and metabolic disorders. This thesis aimed to investigate the distribution of the heterochromatin mark H3K9me3 in the intestine with an emphasis on ISCs, using the Drosophila midgut and mouse intestinal organoids as models. Confocal microscopy was used together with cell-type-specific fluorescent staining, to obtain the expression of the H3K9me3 specific histone methyltransferase Su(var)3-9, in the midgut. An antibody was used for the detection of H3K9me3 distribution along the anterior/posterior axis in Su(var)3-9 overexpressed flies. Additionally, DNA adenine methyltransferase identification (DamID) was applied in order to find target genes of the H3K9me3 regulation in the genome with the specific chromo domain of M-phase phosphoprotein 8 (MPHOSPH8) that binds to H3K9me3. The number of lineage-labeled differentiated enterocytes was shown to be locally higher in the Su(var)3-9 overexpressed flies compared with the control, although the flies were on starvation without nutrient-induced activation. Moreover, the number of lineage-labeled progenitor cells was not remarkably altered between the samples. However, the intensity of H3K9me3 was significantly higher throughout the whole midguts in the Su(var)3-9 overexpressed flies in comparison to the control. According to one replicate, the DamID in mouse intestinal organoids revealed that the peaks of H3K9me3 were divergent between the samples grown in different conditions. The first sample was assumed to contain more ISCs, whereas the other one was assumed to contain more differentiated intestinal cells. According to my results, the Su(var)3-9 overexpression drives the stem cells against the differentiation of enterocytes. Furthermore, the MPHOSPH8 chromo domain in the organoids was successfully applied in DamID; thus, more replicates should be prepared for additional analysis, because I found several potential target genes of H3K9me3. In the future, it is important to further study the epigenetic regulation of ISCs, for applying the epigenetic marks as targets for the treatment of many human pathophysiological conditions, such as cancer, obesity, and metabolic disorders.

The group has identified two rare, previously uncharacterized missense variants in the YBX3 gene in a Finnish patient presenting with an unusual form of nemaline myopathy. The patient also inherited two biallelic TPM3 variants, one RYR1 variant from the father and one SRPK3 variant from the mother. TPM3 and RYR1 are known nemaline myopathy causing genes and the other variants identified in the patients, including the YBX3 variants, are thought to have a modifying effect on the phenotype. YBX3 encodes Y-box binding protein 3 (YB-3) and, YB-3 is a member of the Y-box binding (YB) protein family, that in addition to YB-3 consists of YB-1 and YB-2. The YB-proteins have mainly been studied in the context of cancer, with most studies focusing on YB-1. Studies indicate the ability of YB-proteins to compensate for the loss of one homolog suggesting functional redundancy between YB-3 and YB-1, and YB-3 and YB-2. Compared to its homologs, YB-3 is highly expressed in skeletal muscle. The aim of this thesis was to try out a new cell culturing method when investigating the role of YB-3 in the differentiation of myoblasts into myotubes. MSY-3 is the murine orthologue of YB-3. MSY3-knockdown mouse C2C12 myoblast lines were established using GIPZ lentiviral short hairpin constructs and by selection with puromycin. The success of transfection was determined using qPCR. The myoblasts were differentiated for 20 days on a gelatin hydrogel surface to support long-term culture and to provide phenotypes of higher physiological relevance with improved contractile maturity. Myoblasts cultured on coverslips were immunofluorescently stained for MSY-3. HeLa cells were transfected with a construct encoding N-terminally FLAG-tagged human YB-3 in a pcDNA-vector. YB-3-FLAG was purified using anti-FLAG magnetic beads. The eluated immunoprecipitation sample was sent to N-terminal sequencing to obtain information on post-translational modifications, to support further experiments regarding the post-translational cleavage of YB-3. N-terminal sequencing revealed an enrichment of YB-3 and YB-1 in the immunoprecipitation sample but not of YB-2, and previously undescribed post-translational modifications were identified. The MSY3-knockdown myotubes exhibited no spontaneous twitching on the hydrogel, while the control C2C12 myotubes twitched frequently. Misalignment of the MSY3-knockdown myotubes and changes in morphology was also observed in one of the MSY3-knockdown cell lines. This suggests that differentiating myoblasts on gelatin hydrogel is a potential strategy for studying the functions of YB-3 in myoblast differentiation and to elucidate its role in skeletal muscle.