Disease relevance of Bmp8b

• Previous studies have shown that targeted mutagenesis of Bmp8b causes male infertility due to germ cell degeneration [1].

High impact information on Bmp8b

• In the mouse, Bmp8b is expressed in male germ cells of the testis and trophoblast cells of the placenta, suggesting that it has a role in spermatogenesis and reproduction [2].
• The gene encoding bone morphogenetic protein 8B is required for the initiation and maintenance of spermatogenesis in the mouse [2].
• It has been shown that heterodimers of DPP and 60A classes of bone morphogenetic proteins (BMPs) are more potent than each homodimers in bone and mesoderm induction in vitro, suggesting that BMP4 and BMP8B may form heterodimers to induce PGCs [3].
• Bmp8a and Bmp8b are expressed in similar patterns in male germ cells [1].
• The murine Bmp8a and Bmp8b genes are tightly linked on mouse chromosome 4 and have similar expression during reproduction [1].

Biological context of Bmp8b

• Evidence that mouse Bmp8a (Op2) and Bmp8b are duplicated genes that play a role in spermatogenesis and placental development [4].
• On a largely C57BL/6 background, Bmp8b null mutants completely lack PGCs, and Bmp8b heterozygotes have a reduced number of PGCs [5].
• In the testis of adult Bmp8b homozygous mutant males, the Madr1- expressing pachytene spermatocytes are the first cell population to show increased apoptosis [6].

Anatomical context of Bmp8b

• In addition, both Bmp8a and Bmp8b are expressed in the testis during specific stages of spermatogenesis, with the highest levels of RNA in stage 6-8 round spermatids after 3 weeks of age [4].
• By contrast, high levels of Bmp8b RNA are found in the decidual cells of the uterus, and both genes are expressed in the trophoblast cells of the labyrinthine region of the placenta and in the inner root sheath of hair follicles of early postnatal skin [4].
• Requirement of Bmp8b for the generation of primordial germ cells in the mouse [5].
• In this study, we report that Bmp8b, a member of the Gbb-60A class of the BMP superfamily, is expressed in the extraembryonic ectoderm in pregastrula and gastrula stage mouse embryos and is required for PGC generation [5].
• In addition, Bmp8b homozygous null embryos on both genetic backgrounds have a short allantois, and this organ is missing in some more severe mutants [5].

Other interactions of Bmp8b

• Previous studies have demonstrated that extraembryonic ectoderm-derived BMP4 and BMP8B are both required for PGC generation [7].
• We have previously shown that Bmp7, Bmp8a, and Bmp8b of the 60A class of Bmp genes have additive effects in spermatogenesis and in maintaining the epididymal integrity of the caput and caudal regions [8].

References