Browsing by Author "Wartiovaara, Linnea"

Renewal of the intestinal epithelium is driven by the actively dividing and strictly regulated Lgr5-expressing intestinal stem cells (ISCs). As uncontrolled proliferation may lead to colorectal cancer (CRC), ISCs and the regulatory circuit around them could elucidate new targets for colorectal cancer therapy. The regulatory crosstalk between the stem cells and surrounding stroma is under intensive investigation, but little is known about the neuronal control of the intestinal epithelium. Adrenergic signals from sympathetic nervous system regulate hematopoietic and melanocyte stem cells and promote tumorigenesis in e.g., pancreatic, and prostate cancer. Adra2a, one of the nine different adrenergic receptors, is expressed in the ISCs, and adrenergic neurons project neurites to the stem cell niche suggesting a paracrine signaling role. However, whether the adrenergic signaling plays a role in ISC regulation and/or in colorectal cancer remains unknown. The aim of this study was to develop tools to investigate the role of adrenergic signaling in ISC regulation. First, I set up a protocol to delete Adra2a and other genes in intestinal organoids recapitulating the stem cell hierarchy of the intestinal epithelium in vitro, using CRISPR-Cas9 technology. This led to successful deletion of the Ret proto-oncogene while an Adra2a-deficient organoid pool could not be established with these efforts. I differentiated neuroblastoma cells to a catecholaminergic phenotype and cultured them together with intestinal organoids to address the effect of catecholaminergic signaling on the intestinal epithelium in organoid cocultures. The coculture with catecholaminergic cells induced upregulation of the regeneration markers Ly6a and Clu in intestinal organoids, while Reg3b as well as the stem cell markers Lgr5, Olfm4, and Adra2a and the Paneth cell marker Lyz1 were reduced. Third, I assessed the direct effect of a 3-hour norepinephrine (NE) pulse on wild-type organoids with 3’RNA sequencing, however, this did not induce significant changes in the expression levels of the respective regeneration marker genes. Altogether, my work established a CRISPR-Cas9-based method to delete genes of interest in primary intestinal organoids. Further investigation is needed to verify if NE contributes to the regulation of intestinal regeneration and stem cell maintenance.