The present study examined the effect of exogenous thrombospondin 1 (TSP1) on the steroidogenic function of luteal cells cultured invitro. Furthermore, the transcriptional interaction of insulin with TSP1 and its receptor, cluster of differentiation 36 (CD36) were also investigated. At the highest dose (500ngmL−1) TSP1 significantly downregulated the expression of the angiogenic marker von Willebrand factor (vWF) and progesterone production in cultured luteal cells. Moreover, the simultaneous upregulation in the expression of caspase 3 by exogenous TSP1 was consistent with a reduction in the number of viable luteal cells as determined by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltertrazolium bromide (MTT) assay after 72h of culture. However, the expression of critical enzymes in the progesterone synthetic pathway was not significantly modulated by treatment with TSP1 in cultured luteal cells. Knocking out of endogenous TSP1 with the clustered regularly interspaced short palindromic repeats (CRISPR)/ CRISPRassociated protein9 (Cas9) system improved the viability of luteal cells as well as increasing progesterone production and decreasing caspase 3 activation. Insulin treatment suppressed the expression of TSP1 and CD36 in cultured luteal cells in a dose- and time-dependent manner. To conclude, TSP1 acts as a negative endogenous regulator of angiogenesis that attenuates progesterone production, possibly by reducing the number of luteal cells via apoptosis during luteal regression, whereas insulin as a luteinising signal may have inhibited the thrombospondin system for the efficient development of luteal function.
BMPs are multifunctional growth factors implicated in regulating the ovarian function as key intra-ovarian factors. Biological effects of BMPs are mediated through binding with membrane bound receptors like BMPR-IB and initiating downstream Smad signaling pathway. FecB mutation, regarded as a loss of function mutation in the BMPR-IB gene was identified in certain sheep breeds having high fecundity. Similar type of fecundity genes in goats have not been discovered so far. Hence, the current study was designed to investigate the effects of BMPR-IB gene modulation on granulosa cell function in goats. The BMPR-IB gene was knocked out using CRISPR-Cas technology in granulosa cells and cultured in vitro with BMP-4 stimulation for three different durations In addition, the FecB mutation was introduced in the BMPR-IB gene applying Easi-CRISPR followed by BMP-4/7 stimulation for 72 h. Steroidogenesis and cell viability were studied to explore the granulosa cell function on BMPR-IB gene modulation. BMPRs were found to be expressed stage specifically in granulosa cells of goats. Higher transcriptional abundance of R-Smads, LHR and FSHR indicating sensitisation of Smad signaling and increased gonadotropin sensitivity along with a significant reduction in the cell proliferation and viability was observed in granulosa cells upon BMPR-IB modulation. The inhibitory action of BMP-4/7 on P4 secretion was abolished in both KO and KI cells. Altogether, the study has revealed an altered Smad signaling, steroidogenesis and cell viability upon modulation of BMPR-IB gene in granulosa cells similar to that are documented in sheep breeds carrying the FecB mutation.
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