LPS impairs steroidogenesis and ROS metabolism and induces PPAR transcriptional activity to disturb estrogen/androgen receptor expression in testicular cells
Inflammation can deregulate the testicular functions of steroidogenesis and spermatogenesis, consequently contributing to male infertility. Animals and cells treated with lipopolysaccharide (LPS) exhibit infection- and inflammation-induced testicular dysfunction. However, the precise mechanisms affecting steroidogenesis and spermatogenesis in response to LPS-treatment remain poorly understood. We isolated distinct testicular cells including spermatocytes, round spermatids and late spermatids to analyze distribution of peroxisome proliferator-activated receptor (PPAR) family, plays central roles in the regulation of metabolism. Our results suggested Pparα/Pparγ mRNA was highly expressed in late spermatids, while Pparβ mRNA was highly expressed in round spermatids. To analyze the effect of LPS on testicular cells, we established an LPS infection model using primary Sertoli cells and testicular cell lines (TM4, GC2 and MLTC1). We observed that PPARγ and SIRT1 were concentrated in the nuclear region and that the mRNA expression levels of antioxidative enzymes (Cat and Homx1) and PPARγ were upregulated in primary Sertoli cells after LPS-treatment. Moreover, luciferase reporter gene assays of the testicular cell lines revealed that the activity of the PPAR response element (PPRE) was significantly increased. Importantly, the transcriptional activity of the androgen response element was significantly reduced, whereas activity of estrogen response element was strongly induced in LPS-treated TM4 cells, consistent with the RT-PCR results. Meanwhile, the qRT-PCR results revealed that the LPS-induced upregulation of Ar mRNA in MLTC1 cells and Erβ mRNA in TM4 cells were significantly recovered after treatment with the specific PPARγ-antagonist GW9662. In addition, we also found that LPS induced alterations in enzymes involved in steroidogenesis in testicular cell lines. Taken together, our results revealed that LPS may induce PPAR transcriptional activity to disturb estrogen/androgen receptor expression and impair steroidogenesis and ROS metabolism in testicular cells.
KeywordsLipopolysaccharide (LPS) Estrogen/androgen receptor Peroxisome proliferator-activated receptor (PPAR) Sirtuin Testis
Analysis of variance
Antioxidant response element
Enzyme-linked immunosorbent assay
Estrogen response element
Fetal bovine serum
Luteinizing hormone receptor
Polymerase chain reactions
Peroxisome proliferator-activated receptor
PPAR response element
Polyunsaturated fatty acids
Quantitative real-time PCR
Reactive oxygen species
Silent information regulator type 1
The excellent technical assistance of Yayun Fang and Danni Shan is gratefully acknowledged.
GW, YX and LJ conceived of and designed the experiments; GW, SC and SZ performed the experiments; GW, YZ and YX analyzed the results; GW and SC contributed reagents/materials/analysis tools; GW, YX and LJ wrote the manuscript. All authors reviewed the manuscript.
This work was supported by grants from the Health Commission of Hubei Province Scientific Research Project (Grant Nos. WJ2019H013 and WJ2019H023) and the Fundamental Research Funds for the Central Universities (Grant No. 2042019kf0150). The funders had no role in the study design, data collection, data analysis, decision to publish, or preparation of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
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