NCBI Summary:
The protein encoded by this gene acts as a homotetramer to catalyze the conversion of homocysteine to cystathionine, the first step in the transsulfuration pathway. The encoded protein is allosterically activated by adenosyl-methionine and uses pyridoxal phosphate as a cofactor. Defects in this gene can cause cystathionine beta-synthase deficiency (CBSD), which can lead to homocystinuria. Multiple alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, May 2010]
General function
Enzyme
Comment
Cellular localization
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Ovarian function
Oocyte maturation, Early embryo development
Comment
Cystathionine beta synthase participates in murine oocyte maturatione mediated by homocysteine. Liang R et al. Our previous study demonstrated that cystathionine beta synthase (CBS) is highly expressed in the cumulus-oocyte complex during ovulation. However, the role of CBS during oocyte maturation remains uncertain. In this study, a small-interfering (si) RNA interference (siRNA) approach was used to investigate the potential role of CBS during oocyte maturation. Accompanied with a gradual increase of homocysteine, the introduction of CBS-siRNA into murine granulosa cells selectively depleted the corresponding target mRNA and protein for CBS as assessed by semi-quantitative reverse-transcriptase PCR (RT-PCR) and immuofluorescence staining. When fully grown, germinal vesicle (GV) oocytes matured in vitro for 16h using medium from transfected granulosa cells, the functional suppression of CBS resulted in a significant increase in the rate of GV-arrested oocytes. The results of this study provide evidence that CBS participates in the process of oocyte maturation. Furthermore, this effect may be fulfilled by conditioning the level of homocysteine in the microenvironment of the oocyte.
Expression regulated by
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Ovarian localization
Oocyte, Granulosa, Theca
Comment
Hydrogen Sulfide Donor Protects Porcine Oocytes against Aging and Improves the Developmental Potential of Aged Porcine Oocytes. Krejcova T et al. (2015) Porcine oocytes that have matured in in vitro conditions undergo the process of aging during prolonged cultivation, which is manifested by spontaneous parthenogenetic activation, lysis or fragmentation of aged oocytes. This study focused on the role of hydrogen sulfide (H2S) in the process of porcine oocyte aging. H2S is a gaseous signaling molecule and is produced endogenously by the enzymes cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (MPST). We demonstrated that H2S-producing enzymes are active in porcine oocytes and that a statistically significant decline in endogenous H2S production occurs during the first day of aging. Inhibition of these enzymes accelerates signs of aging in oocytes and significantly increases the ratio of fragmented oocytes. The presence of exogenous H2S from a donor (Na2S.9H2O) significantly suppressed the manifestations of aging, reversed the effects of inhibitors and resulted in the complete suppression of oocyte fragmentation. Cultivation of aging oocytes in the presence of H2S donor positively affected their subsequent embryonic development following parthenogenetic activation. Although no unambiguous effects of exogenous H2S on MPF and MAPK activities were detected and the intracellular mechanism underlying H2S activity remains unclear, our study clearly demonstrates the role of H2S in the regulation of porcine oocyte aging.//////////////////
Localization of cystathionine beta synthase in mice ovaries and its expression profile during follicular development. Liang R et al. BACKGROUND: In vitro fertilization (IVF) researches have suggested that cystathionine beta synthase (CBS) is involved in oocyte development. However, little is known about the regional and cellular expression patterns of CBS in the ovary. The purpose of this study was to analyze the localization of CBS in mice ovaries and to investigate the expression profile during follicular development. METHODS: We used in situ hybridization and immunohistochemical analysis to determine CBS expression in the ovaries of female Balb/c mice. Then the follicles were collected from F1 (C57BL x Balb/c) mice and cultured in vitro. With the method of semi-quantitative RT-PCR, we also investigated the expression profile of CBS during follicular development. RESULTS: CBS was absent in the oocytes, although it was ubiquitously expressed in the ovary with the strongest expression in follicular cells at all stages. In late antral follicles, CBS expression was markedly higher in granulosa cells located close to the antrum and in cumulus cells around the oocyte. The semi-quantitative RT-PCR showed that CBS mRNA was detected in follicles at all stages in vitro. In cumulus-oocyte complexes superovulated, CBS expression also increased rapidly. CONCLUSIONS: CBS was located mainly in the follicular cells in the ovaries. The level of CBS expression is high in follicles during folliculogenesis in mice. Differences in the CBS expression profile between oocyte and follicular cells suggest a role for CBS as a mediator in interactions between oocyte and granulosa cells.