Lactate promotes specific differentiation in bovine granulosa cells depending on lactate uptake thus mimicking an early post-LH stage

Abstract

BackgroundThe LH-induced folliculo-luteal transformation is connected with alterations of the gene expression profile in cells of the granulosa layer. It has been described that hypoxic conditions occur during luteinization, thus favoring the formation of L-lactate within the follicle. Despite being a product of anaerobic respiration, L-lactate has been shown to act as a signaling molecule affecting gene expression in neuronal cells. During the present study, we tested the hypothesis that L-lactate may influence differentiation of follicular granulosa cells (GC).MethodsIn a bovine granulosa cell culture model effects of L- and D-lactate, of increased glucose concentrations and of the lactate transport inhibitor UK5099 were analyzed. Steroid hormone production was analyzed by RIA and the abundance of key transcripts was determined by quantitative real-time RT-PCR.ResultsL-lactate decreased the production of estradiol and significantly affected selected genes of the folliculo-luteal transition as well as genes of the lactate metabolism. CYP19A1, FSHR, LHCGR were down-regulated, whereas RGS2, VNN2, PTX3, LDHA and lactate transporters were up-regulated. These effects could be partly or completely reversed by pre-treatment of the cells with UK5099. The non-metabolized enantiomer D-lactate had even more pronounced effects on gene expression, whereas increased glucose concentrations did not affect transcript abundance.ConclusionsIn summary, our data suggest that L-lactate specifically alters physiological and molecular characteristics of GC. These effects critically depend on L-lactate uptake, but are not triggered by increased energy supply. Further, we could show that L-lactate has a positive feedback on the lactate metabolism. Therefore, we hypothesize that L-lactate acts as a signaling molecule in bovine and possibly other monovular species supporting differentiation during the folliculo-luteal transformation.Electronic supplementary materialThe online version of this article (10.1186/s12958-018-0332-3) contains supplementary material, which is available to authorized users.

Low Oxygen Levels Induce Early Luteinization Associated Changes in Bovine Granulosa Cells

“…These findings were further strengthened by the identification of increased glucose consumption and lactate accumulation in post hCG murine follicles ( Harris et al, 2007 ). Recently, it was shown that even under normoxic conditions lactate can act as an effective signaling molecule that induces granulosa cell differentiation ( Baufeld and Vanselow, 2018 ).…”

A Tissue Culture Model of Estrogen-producing Primary Bovine Granulosa Cells

“…According to previous testing, cryopreservation does not affect the GC phenotype or steroid production in culture. Also, the abundance of marker transcripts in cultured cells did not reveal significant differences comparing samples prepared from freshly isolated cells with those previously subjected to cryopreservation 16 .…”

“…Two-tailed Student's t -test, the p -values are included. This figure is reproduced from Baufeld and Vanselow 16 . Please click here to view a larger version of this figure.…”

Effects of Dietary Fatty Acids on Bovine Oocyte Competence and Granulosa Cells

“…Later, cDNA was synthesized using the SensiFAST cDNASynthesis Kit (Bioline, Luckenwalde, Germany) from 200 ng RNA as done previously (23). The RT-qPCR was executed for gene expression analysis, using SensiFAST SYBR No-ROX (Bioline) with gene-specific primers ( Supplementary Table 3) in a Light Cycler 96 instrument (Roche, Mannheim, Germany) (24).…”