COL1A1 regulates the proliferative function of goat ovarian granulosa cells via PI3K/AKT/mTOR pathway.

Collagen type I alpha 1 chain (COL1A1) is a key component of type I extracellular matrix collagen. It plays a crucial role in supporting normal ovarian function in both humans and animals. Though COL1A1 regulates spermatogonial migration, spermatogenic apoptosis, and steroid secretion in testicular stromal cells, its regulatory role in ovarian granulosa cells (OGCs) remains unclear. This study characterized COL1A1 expression in Guizhou Black goat ovaries (divergent fecundity) and elucidated how it modulates OGC activity. A total of 12 Guizhou Black goats were classified into monotocous and polytocous groups based on their historical litter size records: monotocous goats produce one kid per litter, while polytocous goats bear two or more kids per litter. Immunohistochemistry was used to locate COL1A1 in ovarian follicles; qRT-PCR and Western blotting were applied to detect gene and protein expression. CCK-8, flow cytometry and ROS detection assays were performed to evaluate OGC proliferation, cell cycle distribution, apoptosis level and intracellular ROS content after COL1A1 overexpression and downexpression. COL1A1 protein and gene expression in ovarian follicles and tissues were significantly upregulated in the polytocous group compared with the monotocous group. COL1A1 overexpression markedly increased estradiol secretion and the expression of fecundity-related genes (GDF9, FSHβ, BMP15, BMPR-1B), reduced intracellular ROS accumulation, promoted OGC cycle progression from G1/G0 to G2/M phase, and upregulated PCNA protein level as well as the phosphorylation ratios of PI3K, AKT and mTOR. Meanwhile, it inhibited the expression of pro-apoptotic genes BAX, caspase-3 and caspase-9. COL1A1 downexpression exerted the opposite biological effects on above indicators. COL1A1 modulates OGC activity to facilitate follicular development and maturation by activating the PI3K/AKT/mTOR signaling pathway and mitigating intracellular ROS production.