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Comment |
Research Resource: Pre-ovulatory LH surge effects on follicular theca and granulosa transcriptomes. Christenson LK et al. The molecular mechanisms that regulate the pivotal transformation processes observed in the follicular wall following the pre-ovulatory LH-surge, are still not established, particularly for cells of the thecal layer. To elucidate thecal and granulosa cell type-specific biological functions and signaling pathways, large dominant bovine follicles were collected before and 21 hrs after an exogenous GnRH induced LH surge. Antral granulosa (aGC; aspirated by follicular puncture) and membrane-associated granulosa (mGC; scraped from the follicular wall) were compared to thecal cell expression profiles determined by mRNA microarrays. Of the ~11,000 total genes expressed in the peri-ovulatory follicle, only 2% of thecal versus 25% of the granulosa genes changed in response to the LH surge. The majority of the 203 LH-regulated thecal genes were also LH regulated in granulosa cells, leaving a total of 57 genes as LH-regulated theca cell specific genes. Of the 57 thecal specific LH-regulated genes, 74% were downregulated including CYP17A1 and NR5A1, while most other genes are being identified for the first time within theca. Many of the newly identified upregulated thecal genes (e.g., PTX3, RND3, PPP4R4) were also upregulated in granulosa. Minimal expression differences were observed between aGC and mGC, however, transcripts encoding extracellular proteins (NID2) and matrix modulators (ADAMTS1, SASH1) predominated these differences. We also identified large numbers of unknown LH-regulated granulosa cell genes and discuss their putative roles in ovarian function. This Research Resource provides an easy to access global evaluation of LH regulation in thecal and granulosa cells that implicate numerous molecular pathways hereto unknown within the follicle.
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