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Investigation of cpeb1 transcript regulation and potential functions of CPEB1 in germline development in X. laevis

dc.contributor.advisorPieler, Tomas Prof. Dr.
dc.contributor.authorSmarandache, Anita Klarisa Andreea
dc.titleInvestigation of cpeb1 transcript regulation and potential functions of CPEB1 in germline development in X. laevisde
dc.contributor.refereePieler, Tomas Prof. Dr.
dc.description.abstractengGermline specification represents the first functional segregation between two cell populations in the embryo. The germ cell lineage is the source of genetic variation and is essential for the continuity of the species. In X. laevis, primordial germ cells (PGCs) inherit distinct maternal determinants present in the germ plasm. They are required for the specification and maintenance of germline identity during early embryogenesis. Intriguingly, during the maternal to zygotic transition, which represents the most profound change in the life of an embryo as the maternally contributed factors are cleared and the zygotic genome is activated, transcripts provided in the germplasm are efficiently depleted in the soma, nevertheless circumvent degradation in the germline. In a genome-wide RNA sequencing analysis performed in our lab to determine the overlap and the distinctions between the transcript pools of primordial germ cells with their somatic neighbors, cpeb1 was identified as germline specific. Cpeb1 transcripts are depleted at MZT, yet upon inhibition of miRNA maturation, cpeb1 mRNA levels increase substantially in gastrulating embryos. Therefore, somatic degradation of cpeb1 probably occurs via miRNA-mediated decay, a key player during MZT. In the present study I addressed the mechanisms regulating the restriction of cpeb1 transcripts to PGCs and the potential role the encoded protein could exert in the formation of the germline. Initially, I identified a minimal regulatory region in the cpeb1 3’UTR by analyzing the distribution of exogenous chimeric reporter constructs in the germline and surrounding somatic tissues. By using two complementary approaches for identifying miRNA-mRNA pairs I attempted to determine which miRNAs are responsible for the depletion of cpeb1. The results suggest that a 25bp region in the proximal 3’UTR sequence is involved in transcript regulation. Nevertheless, the identity of the miRNAs remains to be determined. CPEB1 is involved in oocyte maturation by regulating the timing and extent of translation for bound transcripts, a mechanism described in minute detail. Nonetheless, little is known about what role CPEB1 could play in germline development. To address this, I overexpressed dominant negative mutants lacking the N-terminus and flag-tagged CPEB1, which lead to a decrease in germ cell numbers. To determine how this effect is induced, I identified candidate interaction partners by mass spectrometry analysis. The functional diversity of potential interactions suggests that CPEB1 may be involved in a complex array of cellular
dc.contributor.coRefereeShcherbata, Halyna Dr.
dc.subject.engXenopus laevisde
dc.subject.engpost-transcriptional regulationde
dc.affiliation.instituteGöttinger Zentrum für molekulare Biowissenschaften (GZMB)de
dc.subject.gokfullMolekularbiologie, Gentechnologie (PPN619462973)de

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