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Comment |
Expression of EGFL7 in primordial germ cells and in adult ovaries and testes. Campagnolo L et al. We have previously reported the isolation and characterization of a novel endothelial-restricted gene, Egfl7, that encodes a secreted protein of about 30-kDa. We and others demonstrated that Egfl7 is highly expressed by endothelial cells during embryonic development and becomes down-regulated in the adult vasculature. In the present paper, we show that during mouse embryonic development, Egfl7 is also expressed by primordial germ cells (PGC). Expression is down-regulated when PGCs differentiate into pro-spermatogonia and oogonia, and by 15.5dpc Egfl7 can no longer be detected in the germ line of both sexes. Notably, Egfl7 is again transiently up-regulated in germ cells of the adult testis. In contrast, expression in the ovary remains limited to the vascular endothelium. Our results provide the first evidence of a non-endothelial expression of EGFL7 and suggest distinctive roles for Egfl7 in vascular development and germ cell differentiation.
Egfl7, a novel epidermal growth factor-domain gene expressed in endothelial cells.
Fitch MJ, et al report the cloning and characterization of a novel epidermal growth factor (EGF) domain gene that was identified in a retroviral gene entrapment screen and is expressed in endothelial cells. This gene encodes a protein of 278 amino acids with an amino-terminal signal peptide and two centrally located EGF-like domains. We have named this novel gene in accordance with the guidelines of the Mouse Genome Informatics group Egfl7, for EGF-like domain 7. Egfl7 mRNA is expressed in highly vascularized adult tissues such as the lung, heart, uterus, and ovary. In addition, Egfl7 is expressed early during mouse embryogenesis and in undifferentiated murine embryonic stem cells. The analysis of Egfl7 expression in embryonic day 9.5 embryos by in situ hybridization indicates that Egfl7 is expressed in vascular structures in both the embryo proper and the yolk sac and at sites of mesodermal precursors of angioblasts. Within the cell, EGFL7 protein is localized to the endoplasmic reticulum and Golgi apparatus, suggesting that the protein is targeted for secretion. Indeed, recombinant EGFL7 is readily detectable in the supernatant media of transiently transfected HEK293 cells. We also report the identification of an Egfl7 paralog, Egfl8, and show that EGFL8 protein shares similar domains and molecular weight with EGFL7. Developmental Dynamics 230:316-324, 2004.
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