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Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Indian hedgehog and beta-catenin signaling: role in the sebaceous lineage of normal and neoplastic mammalian epidermis.

In mammalian epidermis, the level of beta-catenin signaling regulates lineage selection by stem cell progeny. High levels of beta-catenin stimulate formation of hair follicles, whereas low levels favor differentiation into interfollicular epidermis and sebocytes. In transgenic mouse epidermis, overexpression of beta-catenin leads to formation of hair follicle tumors, whereas overexpression of N-terminally truncated Lef1, which blocks beta-catenin signaling, results in spontaneous sebaceous tumors. Accompanying overexpression of beta-catenin is up-regulation of Sonic hedgehog ( SHH) and its receptor, Patched (PTCH/ Ptch). In DeltaNLef1 tumors Ptch mRNA is up-regulated in the absence of SHH. We now show that PTCH is up-regulated in both human and mouse sebaceous tumors and is accompanied by overexpression of Indian hedgehog ( IHH). In normal sebaceous glands IHH is expressed in differentiated sebocytes and the transcription factor GLI1 is activated in sebocyte progenitors, suggesting a paracrine signaling mechanism. PTCH1 and IHH are up-regulated during human sebocyte differentiation in vitro and inhibition of hedgehog signaling inhibits growth and stimulates differentiation. Overexpression of DeltaNLef1 up-regulates IHH and stimulates proliferation of undifferentiated sebocytes. We present a model of the interactions between beta-catenin and hedgehog signaling in the epidermis in which SHH promotes proliferation of progenitors of the hair lineages whereas IHH stimulates proliferation of sebocyte precursors.[1]


  1. Indian hedgehog and beta-catenin signaling: role in the sebaceous lineage of normal and neoplastic mammalian epidermis. Niemann, C., Unden, A.B., Lyle, S., Zouboulis, C.h.C., Toftgård, R., Watt, F.M. Proc. Natl. Acad. Sci. U.S.A. (2003) [Pubmed]
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