The extracellular matrix (ECM) is a major component of the ovarian stroma. Collagen and hyaluronan (HA) are critical ovarian stromal ECM molecules that undergo age-dependent changes in the mouse and human. How these matrix components are regulated and organized in other mammalian species with reproductive characteristics similar to women such as cows and pigs, has not been systematically investigated. Therefore, we performed histological, molecular, and biochemical analyses to characterize collagen and HA in these animals. Bovine ovaries had more collagen than porcine ovaries when assessed biochemically, and this was associated with species-specific differences in collagen gene transcripts: Col3a1 was predominant in cow ovaries while Col1a1 was predominant in pig ovaries. We also observed more HA in the porcine vs. bovine ovary. HA was distributed across three molecular weight ranges (300 kDa) in ovarian tissue and follicular fluid, with tissue having more >300 kDa HA than the other two ranges. Transcripts for HA synthesis and degradation enzymes, Has3 and Hyal2, respectively, were predominant in cow ovaries, whereas Has2, Kiaa1199, and Tmem2 tended to be predominant in pig ovaries. Together, our findings have implications for the composition, organization, and regulation of the ovarian ECM in large mammalian species, including humans.

The organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 are hepatic transporters that mediate the uptake of numerous therapeutics like antibiotics and statins. Various post-translational modifications, eg, phosphorylation and glycosylation, have been shown to impact OATP1B1 and OATP1B3 function and localization. S-palmitoylation (also known as S-acylation or palmitoylation) is a reversible post-translational modification that adds palmitic acid (C16:0) to cysteine residues and can influence a protein's function, localization, and protein-protein interactions. In this study, we investigated and characterized palmitoylation in OATP1B1 and OATP1B3. Using site-directed mutagenesis and acyl-resin-assisted capture assays, residue Cys24 was identified as the palmitoylation site for both these proteins. Uptake function and surface biotinylation experiments demonstrated that palmitoylation does not affect the individual function and surface expression of OATP1B1 and OATP1B3. Coexpression studies revealed a decrease in OATP1B1-OATP1B3 interactions when nonpalmitoylated OATP1B1 or nonpalmitoylated OATP1B3 are coexpressed with their wild-type counterparts, suggesting that S-palmitoylation regulates protein-protein interactions between OATP1B1 and OATP1B3. SIGNIFICANCE STATEMENT: This study identified and characterized palmitoylation of the organic anion transporting polypeptide (OATP) 1B1 and OATP1B3. Both OATP1B1 and OATP1B3 can be palmitoylated on the conserved Cys24 residue. Palmitoylation of these 2 transporters does not impact their individual function or surface expression. However, the interaction between these 2 proteins is affected when their palmitoylation state is altered.