Follicular Fluid High-Density Lipoprotein-Associated Sphingosine 1-Phosphate (S1P) Promotes Human Granulosa Lutein Cell Migration via S1P Receptor Type 3 and Small G-Protein RAC11

Abstract

Coordinated migration and progesterone production by granulosa cells is critical to the development of the corpus luteum, but the underlying mechanisms remain obscure. Sphingosine 1-phosphate (S1P), which is associated with follicular fluid high-density lipoprotein (FF-HDL), was previously shown to regulate ovarian angiogenesis. We herein examined the effects of S1P and FF-HDL on the function of granulosa lutein cells. Both FF-HDL and S1P induced migration of primary human granulosa lutein cells (hGCs) and the granulosa lutein cell line HGL5. In addition, FF-HDL but not S1P promoted progesterone synthesis, and neither of the two compounds stimulated proliferation of granulosa lutein cells. Polymerase chain reaction and Western blot experiments demonstrated the expression of S1P receptor type 1 (S1PR1), S1PR2, S1PR3, and S1PR5 but not S1PR4 in hGCs and HGL5 cells. The FF-HDL- and S1P-induced granulosa lutein cell migration was emulated by FTY720, an agonist of S1PR1, S1PR3, S1PR4, and S1PR5, and by VPC24191, an agonist of S1PR1 and S1PR3, but not by SEW2871 and phytosphingosine 1-phosphate, agonists of S1PR1 and S1PR4, respectively. In addition, blockade of S1PR3 with CAY1044, suramine, or pertussis toxin inhibited hGC and HGL5 cell migration toward FF-HDL or S1P, while blockade of S1PR1 and S1PR2 with W146 and JTE013, respectively, had no effect. Both FF-HDL and S1P triggered activation of small G-protein RAC1 and actin polymerization in granulosa cells, and RAC1 inhibition with Clostridium difficile toxin B or NSC23766 abolished FF-HDL- and S1P-induced migration. The FF-HDL-associated S1P promotes granulosa lutein cell migration via S1PR3 and RAC1 activation. This may represent a novel mechanism contributing to the development of the corpus luteum.

Sphingosine-1-phosphate inhibits H2O2-induced granulosa cell apoptosis via the PI3K/Akt signaling pathway

“…Messenger RNA was detected for S1PR1, S1PR2, S1PR3, and S1PR5, but not for S1PR4. These results are consistent with previous results demonstrating that S1PR4 was expressed on lymphoid and hematopoietic cells and tissues (12,36). Our results also show the expression level of S1PR2 and S1PR5 to be low in comparison with S1PR1 and S1PR3.…”

“…It was previously reported that S1P is present in human follicular fluid (12,31); of note, this concentration of S1P in follicular fluid is comparable to the concentration of S1P used in our experiment. In our preliminary observations, the concentrations of S1P in follicular fluid obtained at oocyte retrieval and in culture medium of in vitro harvested…”

“…Expression of the S1P receptor has recently been reported in human luteinized granulosa cells (12). Messenger RNA was detected for S1PR1, S1PR2, S1PR3, and S1PR5, but not for S1PR4.…”

“…Each receptor subtype exhibits differential coupling efficacy to G-protein alpha subunits and regulates diverse downstream signaling properties, ultimately affecting various molecular and cellular events including cell growth, cell survival, cell migration, and differentiation (11). Sphingosine-1-phosphate inhibits apoptosis in various cell types, and S1PRs are expressed in human granulosa cells (12). Therefore, S1P might have a protective effect against granulosa cell death due to oxidative stress.…”

Roles of Sphingosine-1-Phosphate in Reproduction

“…41 The FF-HDL-associated S1P promotes granulosa lutein cell migration via S1PR3 and RAC1 activation, which may represent a novel mechanism contributing to the development of the corpus luteum. 39 The S1P blocks the luteolytic effect of prostaglandin F-2a by decreasing the activities of caspase 2, 3, and 8 and increasing AKT phosphorylation and TNF-a expression in the pregnant rat. 42 In ovarian transplants, S1P promoted neoangiogenesis and reduced ischemic reperfusion injury.…”