Pancreas lineage allocation and specifciation are regulated by sphingosine-1-phosphate signalling

Identifying the signals that regulate the survival, lineage allocation and specification of pancreas progenitors will help elucidate the embryonic origins of pancreas dysfunction and provide important cues for the efficient conversion of pluripotent stem cells into fully functional ß cells. Several transcription factors regulating the conversion of the early pancreatic progenitors into terminally differentiated cells have been identified but extracellular signals regulating pancreas development are less well understood. Using a combination of genetic approaches, organotypic cultures of embryonic pancreata and genomics we have found that sphingosine-1-phosphate signalling through plays a key role in this process. S1p signalling stabilizes the Hippo pathway effector YAP to promote progenitor survival, acinar and endocrine specification. Endocrine cell specification relies on Gai subunits revealing an unexpected dependence of lineage specification on selected intracellular signalling components. Independently of YAP stabilization, S1p signalling attenuates Notch levels, thus regulating lineage allocation. These findings identify S1p signalling as a key pathway coordinating cell survival, lineage allocation and specification during pancreas development. Overall design: Analysis was carried out at 14.5 dpc embryonic pancreata and in 14.5 dpc embryonic pancreata that have been cultured in air to liquid interface cultures for two days (14.5 + 2). For the 14.5 dpc analysis wild type (14.5 wt) and S1pr2 null (14.5 S1pr2 null) pancreata were analyzed. For the analysis of cultured embryonic pancreata, conditions used were either standard conditions (14.5 + 2) or in the presence of 15 uM of JTE013 (14.5 + 2 + JTE) or in the presence of 15 uM of JTE013 and 50 ng/ml CTGF (14.5 + 2 + JTE + CTGF). Three biological replicates were used for each stage/condition for a total of 15 samples.

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Serafimidis I, Rodriguez-Aznar E, Lesche M, Yoshioka K, Takuwa Y, Dahl A, Pan D, Gavalas A