Microcystin–leucine–arginine causes blood–testis barrier disruption and degradation of occludin mediated by matrix metalloproteinase-8
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Microcystin–leucine–arginine (MC-LR) can cause male reproductive disorders. However, the underlying mechanisms are not yet fully understood. In this study, we aimed to investigate the effects of MC-LR on the integrity of blood–testis barrier (BTB) and the related molecular mechanisms. Both transepithelial electrical resistance measurement in vitro and electron microscope observation ex vivo revealed that MC-LR caused disruption of the tight junction between Sertoli cells, which was paralleled by the degradation of occludin. We observed increased expression of matrix metalloproteinase-8 (MMP-8) upon exposure to MC-LR, and confirmed that abrogation of MMP-8 activity by specific inhibitors as well as transfection with MMP-8 shRNA could abolish the degradation of occludin. Our data demonstrated that MC-LR up-regulated nuclear levels of c-Fos and c-Jun through activating ERK and JNK, and increased NF-κB levels by activating the phosphatidylinositol 3-kinase (PI3K)/AKT cascades. Enhanced binding of c-Fos and NF-κB to the promoter of MMP-8 promoted the transcription of MMP-8 gene. Furthermore, miR-184-3p was significantly downregulated in SC following exposure to MC-LR through targeting MMP-8 expression. Together, these results confirmed that MC-LR-induced MMP-8 expression was regulated at both transcriptional and post-transcriptional levels, which was involved in MC-LR-induced degradation of occludin and BTB destruction. This work may provide new perspectives in developing new diagnosis and treatment strategies for MC-induced male infertility.
KeywordsMicrocystin–leucine–arginine MMP-8 Transcriptional and post-transcriptional levels Occludin degradation
Fetal bovine serum
Phosphatidylinositol 3-kinase (PI3K)
Transepithelial electrical resistance
This work was supported by National Natural Science Foundation of China (31370524, 21377052, and 31670519) and Fundamental Research Funds for the Central Universities (021414380332).
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interests.
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