Expression And Function Of Cysteine Sulfinate Decarboxylase (CSD) In The Mouse Ovary

Taurine is sulfur-containing amino acid and very rich in mammal,and has important functions in body.Cysteine sulfinate decarboxylase(CSD)is the key enzyme of taurine synthesis.The studies of taurine on reproduction and development mainly focus on the early embryonic development and hormone synthesis.There are few reports on the effects of taurine on ovary development,including oocyte and follicle development.In the present study,we explored CSD expressions in mouse ovary and the functions of taurine on mouse ovary.In addition,the regulation of estrogen on CSD expression in ovary was investigated.The results mainly include the following five points:1.HPLC showed that the mouse ovary was with the highest level of taurine in estrous phase and the lowest level in proestrous stage throughout the estrous cycle.Western blot showed that the ovary CSD was expressed with the highest at diestrous stage and the lowest at metaestrous.IHC showed that CSD mainly located in oocytes and granulosa cells of the follicle.In the oocytes,taurine and CSD protein levels were much higher at GVBD and PB1 stages than GV stage.2.We explored the effect of taurine supplement on in vitro culture oocytes.The results showed that exogenous taurine has no effect on oocytes development,and down-regulated the expression of CSD mRNA and protein.RNAi results demonstrated that CSD-siRNA significantly down-regulated CSD mRNA and protein expression plus taurine levels.CSD-siRNA significantly inhibited the rate of oocyte GVBD and the rate of oocyte GVBD restored after taurine supplement.3.In the present study,we generated a knockout mouse for CSD using microinjection of TALEN RNA into pronuclear stage zygotes.As expected,CSD was deleted 30 bps from initiation codon.Mating experiment showed that both the pregnancy rate and number of litters reduced.The further study showed that the number of superovulation significantly decreased in CSD knockout mouse.In addition,the rate of CSD knockout oocyte GVBD also decreased through in vivo and in vitro experiments.4.Western blot showed that CSD protein increased at 17.5 dpc,but decreased at 19.5 dpc,and then increased from PND 1,whereas decreased from PND 14 to adult stage.Serial section further showed that CSD knockout significantly precluded oocyte nest breakdown at PND 4,and did not altered the total number of oocytes.In addition,CSD knockout did not influence follicle development at PND 7,PND 14,PND 21.The results indicated that CSD knockout slowed down primordial follicle formation.5.Estradiol significantly down-regulated CSD levels via in vivo experiment,and the effect of E2 was abrogated by ICI 182780.We further supplement with different concentration taurine into in vitro cultured PND 1 ovary and granulosa cell,and the results showed that E2 significantly dose-dependently decreased CSD levels.ER knockout results showed that ER-? knockout significantly up-regulated CSD levels,but ER-? knockout down-regulated CSD levels.In summary,endogenous taurine promoted oocyte meiotic resumption.CSD knockout significantly slowed down primordial follicle formation and estrogen decreased CSD levels.Our findings provide a better understanding for further study of taurine on related physiological function in the ovary.