This gene encodes a protein that is instrumental in patterning the early embryo. It has been implicated as the key inductive signal in patterning of the ventral neural tube, the anterior-posterior limb axis, and the ventral somites. Of three human proteins showing sequence and functional similarity to the sonic hedgehog protein of Drosophila, this protein is the most similar. The protein is made as a precursor that is autocatalytically cleaved; the N-terminal portion is soluble and contains the signalling activity while the C-terminal portion is involved in precursor processing. More importantly, the C-terminal product covalently attaches a cholesterol moiety to the N-terminal product, restricting the N-terminal product to the cell surface and preventing it from freely diffusing throughout the developing embryo. Defects in this protein or in its signalling pathway are a cause of holoprosencephaly (HPE), a disorder in which the developing forebrain fails to correctly separate into right and left hemispheres. HPE is manifested by facial deformities. It is also thought that mutations in this gene or in its signalling pathway may be responsible for VACTERL syndrome, which is characterized by vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, radial and renal dysplasia, cardiac anomalies, and limb abnormalities. Additionally, mutations in a long range enhancer located approximately 1 megabase upstream of this gene disrupt limb patterning and can result in preaxial polydactyly. [provided by RefSeq, Jul 2008]
Oocyte maturation, Early embryo development
Cyclopamine did not affect mouse oocyte maturation in vitro but decreased early embryonic development. Liu Y 2014 et al.
Hedgehog (Hh) pathway has been studied in various animal body life procedures and is suggested to be important for the development of multiple organs. The genes involved in the Hh signaling pathway were expressed in the ovary of mice, pigs and cattle. However, the function of Hh signaling pathway on oocyte maturation and early embryonic development is still controversial. We detected the effect of sonic hedgehog (Shh) and cyclopamine on the in vitro maturation of mouse oocytes and embryo development. The results showed that the presence of Shh or cyclopamine resulted in similar oocyte maturation to control groups. Shh did not improve early embryonic development. However, the supplement of cyclopamine depressed early embryo development. The mRNA of shh, ptch1, smo and gli1 were less detected in the denuded oocytes. The expression levels of ptch1 ascended from the uncleaved zygote to blastocyst stage. Smo or gli1 were expressed on a higher level at the two-cell or four-cell stage in early embryonic development separately. Therefore, Shh did not affect mouse oocyte maturation and early embryo development, but cyclopamine led to inhibited development of mouse early embryo. The effects of Hh signaling on the oocyte maturation and early embryo development might be species-specific.
Sonic Hedgehog supplemented oocyte and embryo culture media enhances development of in vitro fertilized porcine embryos. Nguyen NT et al. We investigated the expressions of Sonic Hedgehog (SHH) receptor Ptc1 and its co-receptor Smo in fertilized porcine embryos. Effects of exogenous SHH on embryonic development and expressions of survival- and pluripotency-related genes were also determined. We found that Ptc1 and Smo expressed from 2-celled to blastocyst embryos. When oocytes or fertilized embryos were respectively cultured in the maturation or embryo culture medium supplemented with SHH (0.5 ?g/mL), their blastocyst rates and total cell numbers increased (P < 0.05) compared to the untreated control. When cultured in the IVM and IVC media simultaneously supplemented with SHH, the oocytes gained increased blastocyst rates and total cell numbers in an additive manner, with reduced apoptotic indices (P < 0.05). Interestingly, SHH treatment did not affect the expression of BCL-XL gene, yet reduced BAX expression. Blastocysts cultured with various SHH regimes had similar pluripotency-related gene (OCT-4 and CDX2) expressions, but blastocysts derived from SHH treatment during IVM had higher REX-01 expression (P < 0.05). The highest REX-01 expression was observed in the blastocysts derived from SHH-added IVC and from dual IVM and IVC treatments. The levels of acetylated histone 3 (AcH3K9/K14) increased in the 2-celled and the 4-celled embryos when IVM and/or IVC media were supplemented with SHH (P < 0.05). Our findings indicate that SHH conferred a beneficial effect on preimplantation development of porcine embryos, particularly when SHH was supplemented in both IVM and IVC media, and the effects may be carried over from IVM further to the subsequent embryonic development.
Sonic hedgehog promotes porcine oocyte maturation and early embryo development. Nguyen NT et al. In the present study, we investigated the effects of the Sonic hedgehog (Shh) protein on porcine oocyte maturation and early embryo development. Immunohistochemistry showed activation of Shh signalling in cumulus-oocyte complexes (COCs), as reflected by Patched (Ptc), Smoothened (Smo) and Gli1 expression in oocytes, cumulus cells and granulosa cells, particularly those of small follicles (<2 mm in diameter). Western blot analysis showed Smo expression in COCs and in denuded oocytes derived from small and medium (3-7 mm)-sized follicles. Small follicles contained the highest concentration of Shh in follicular fluid compared with medium-sized and large (>7 mm in diameter) follicles. Supplementation with Shh (0.5 or 1 mug mL(-1)) enhanced oocyte maturation compared with the control group (92.4% and 90.4% v. 81.9%, respectively; P < 0.05). This effect was reversed by the simultaneous addition of cyclopamine (1-2 mum), an Shh inhibitor. Similar to intact COCs, denuded COCs showed enhanced maturation following Shh supplementation. Furthermore, cyclin B1 content, extracellular signal-regulated kinase 1/2 phosphorylation, intracellular calcium release, blastocyst rate and total cell numbers were greater (P < 0.05) in oocytes matured in the presence of 0.5 and 1 mug mL(-1) Shh compared with control oocytes. The findings of the present study provide the first evidence that the Shh signalling pathway is active, or at least partially activated, in the porcine ovary and is likely to promote oocyte cytoplasmic and nuclear maturation, as well as subsequent in vitro development, although the underlying mechanisms remain to be elucidated.
Expression regulated by
Wijgerde M, et al reported hedgehog signaling in mouse ovary: Ihh and Dhh from granulosa cells induce target gene expression in developing theca cells.
Follicle development in the mammalian ovary requires interactions between the oocyte, granulosa cells, and theca cells, co-ordinating gametogenesis and steroidogenesis. Here, we show that granulosa cells of growing follicles in mouse ovary act as a source of hedgehog signaling. Expression of indian hedgehog (Ihh) and desert hedgehog (Dhh) mRNAs initiates in granulosa cells at the primary follicle stage, and we find induced expression of the hedgehog target genes Ptch1 and Gli1, in the surrounding pre-theca cell compartment. Cyclopamine, a highly specific hedgehog signaling antagonist, inhibits this induced expression of target genes, in cultured neonatal mouse ovaries. The theca cell compartment remains a target of hedgehog signaling throughout follicle development, showing induced expression of the hedgehog target genes Ptch1, Ptch2, Hip1, and Gli1. In peri-ovulatory follicles, a dynamic synchrony between loss of hedgehog expression and loss of induced target gene expression is observed. Oocytes are unable to respond to hedgehog, since they lack expression of the essential signal transducer Smo (smoothened). The present results point to a prominent role of hedgehog signaling in the communication between granulosa cells and developing theca cells.