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Philipps-Universität Marburg
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Abstract
The human gastrointestinal tract has central digestive, absorptive, homeostatic, metabolic, and protective functions. The epithelium renews itself every 5 to 7 days and is adapted to the needs of organ function by specialized cell types. A special role is played by intestinal stem cells, which control the regeneration of the intestinal epithelium through their self-renewal and multipotency. In case of malignancy so-called cancer stem cells develop, which are held responsible for a large part of therapy resistance, metastasis, and tumor recurrence. The plexin- semaphorin system is essential for physiological processes such as organ development, cell morphology, differentiation, homeostasis, and tissue regeneration. However, it also plays a role in pathophysiological processes, especially in the field of malignant neoplasia. Of particular interest for this dissertation was the transmembrane receptor plexin-B2, which is strongly expressed in the human intestine. An expression analysis of human colon organoids obtained from patient material confirmed this observation. As a basis for further experiments, a stable long-term culture of colon as well as tumor organoids was established. Wnt3a was identified as the driving factor for the successful longterm culture of colon organoids over several weeks. In contrast, tumor organoids only showed growth under Wnt3a-free conditions. For the functional analysis of plexin-B2, lentiviral transduction of human organoids with shRNA plasmids for inducible RNA interference was established and performed. The culture and downstream analysis proved difficult due to various factors. The induction of shRNAs showed insufficient expression reduction of plexin-B1 and B2 and no associable alteration of the stem cell markers LGR5 and EphB2 in the transduced organoids. Repetition of the experiments, improvement of gene transfer and gene silencing by methods such as electroporation and CRISPR/Cas as well as experiments with tumor organoids could be performed in the future to further explore the functional relevance of plexin-B2.
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Dates
Created: 2024Issued: 2024-11-18Updated: 2024-11-18
Faculty
Medizin
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
DFG-subjects
PlexinOrganoideKolorektales KarzinomDarm
DDC-Numbers
610
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Schick, Lea: Funktionelle Analyse von Plexin-B2 in humanen Darmorganoiden. : Philipps-Universität Marburg 2024-11-18. DOI: https://doi.org/10.17192/z2024.0161.