Intestinal hormones are key regulators of digestion and energy homeostasis secreted by rare enteroendocrine cells. These cells produce over ten different hormones including GLP-1 and GIP peptides known to promote insulin secretion. To date, the molecular mechanisms controlling the specification of the various enteroendocrine subtypes from multipotent Neurog3(+) endocrine progenitor cells, as well as their number, remain largely unknown. In contrast, in the embryonic pancreas, the opposite activities of Arx and Pax4 homeodomain transcription factors promote islet progenitor cells towards the different endocrine cell fates. In this study, we thus investigated the role of Arx and Pax4 in enteroendocrine subtype specification. The small intestine and colon of Arx- and Pax4-deficient mice were analyzed using histological, molecular, and lineage tracing approaches. We show that Arx is expressed in endocrine progenitors (Neurog3(+)) and in early differentiating (ChromograninA(-)) GLP-1-, GIP-, CCK-, Sct- Gastrin- and Ghrelin-producing cells. We noted a dramatic reduction or a complete loss of all these enteroendocrine cell types in Arx mutants. Serotonin- and Somatostatin-secreting cells do not express Arx and, accordingly, the differentiation of Serotonin cells was not affected in Arx mutants. However, the number of Somatostatin-expressing D-cells is increased as Arx-deficient progenitor cells are redirected to the D-cell lineage. In Pax4-deficient mice, the differentiation of Serotonin and Somatostatin cells is impaired, as well as of GIP and Gastrin cells. In contrast, the number of GLP-1 producing L-cells is increased concomitantly with an upregulation of Arx. Thus, while Arx and Pax4 are necessary for the development of L- and D-cells respectively, they conversely restrict D- and L-cells fates suggesting antagonistic functions in D/L cell allocation. In conclusion, these finding demonstrate that, downstream of Neurog3, the specification of a subset of enteroendocrine subtypes relies on both Arx and Pax4, while others depend only on Arx or Pax4.
Pubmed ID: 22570716 RIS Download
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A second-generation retrovirus producer lines for the generation of helper free ecotropic and amphotropic retroviruses. The lines are based on the 293T cell line (a human embryonic kidney line transformed with adenovirus E1a and carrying a temperature sensitive T antigen co-selected with neomycin). The unique feature of this cell line is that it is highly transfectable with either calcium phosphate mediated transfection or lipid-based transfection protocols-- up to 50% or higher of cells can be transiently transfected. The lines were created by placing into 293T cells constructs capable of producing gag-pol, and envelope protein for ecotropic and amphotropic viruses. The lines offered advantages over previous stable systems in that virus can be produced in just a few days. Academic and non-profit laboratories may obtain the Phoenix cells from either Allele Biotechnology or the National Gene Vector Bank. The vectors may be obtained from Addgene. They are no longer distributing these reagents from the lab.
View all literature mentionslaboratory mouse with name 129/Sv from MGI.
View all literature mentionsCell line STC-1 is a Cancer cell line with a species of origin Mus musculus
View all literature mentionsThis polyclonal targets Serotonin
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