Developmental expression of Smoc1 and Smoc2 suggests potential roles in fetal gonad and reproductive tract differentiation. Pazin DE et al. SMOC1 and SMOC2 are matricellular proteins thought to influence growth factor signaling, migration, proliferation, and angiogenesis. We examined the expression and regulation of Smoc1 and Smoc2 in fetal gonad/mesonephros complexes to discover possible roles for these genes in gonad and mesonephros development. Smoc1 was upregulated at approximately E10.75 in a center-to-poles wave in pre-Sertoli and pre-granulosa cells and its expression was greatly reduced in Wt1, Sf1, and Fog2 mutants. After E13.5, Smoc1 was downregulated in an anterior-to-posterior wave in granulosa cells but persisted in Sertoli cells, suggesting a sexually dimorphic requirement in supporting cell lineage differentiation. Smoc2 was expressed in Leydig cells, mesonephroi, and Wnt4 mutant ovaries, but not wildtype ovaries. Using organ culture, we determined that Smoc2 expression was dependent on Hedgehog signaling in testes, mesonephroi, and kidneys. Overall, these results demonstrate that SMOC1 and SMOC2 may mediate intercellular signaling and cell type-specific differentiation during gonad and reproductive tract development.
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Secreted modular calcium-binding protein-1 localization during mouse embryogenesis. Gersdorff N et al. BM-40 is an extracellular matrix-associated protein and is characterized by an extracellular calcium-binding domain as well as a follistatin-like domain. Secreted modular calcium-binding protein-1 (SMOC-1) is a new member of the BM-40 family. It consists of two thyroglobulin-like domains, a follistatin-like domain and a new domain without known homologues and is expressed ubiquitously in many adult murine tissues. Immunofluorescence studies, as well as immunogold electron microscopy, have confirmed the localization of SMOC-1 in or around basement membranes of adult murine skin, blood vessels, brain, kidney, skeletal muscle, and the zona pellucida surrounding the oocyte. In the present work, light microscopic immunohistochemistry has revealed that SMOC-1 is localized in the early mouse embryo day 7 throughout the entire endodermal basement membrane zone of the embryo proper. SMOC-1 mRNA is synthesized, even in early stages of mouse development, by mesenchymal as well as epithelial cells deriving from all three germ layers. In embryonic stage day 12, and fetal stages day 14, 16, and 18, the protein is present in the basement membrane zones of brain, blood vessels, skin, skeletal muscle, lung, heart, liver, pancreas, intestine, and kidney. This broad and organ-specific distribution suggests multifunctional roles of SMOC-1 during mouse embryogenesis.