Interleukin-1β signals through a c-Jun N-terminal kinase-dependent inducible nitric oxide synthase and nitric oxide production pathway in sertoli epithelial cells

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Article (peer-reviewed)

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Our recent Sertoli cell (SC) studies showed that the c-Jun N-terminal kinase (JNK) and inducible cyclooxygenase-2 (COX-2) pathways are key regulatory components of IL (IL-1α, IL-1β, and IL-6) expression and START-domain containing StARD1 and StARD5 proteins. IL-1β regulates SC autocrine/paracrine activities and subsequently influences developing germ cells and spermatogenesis. This study was designed to evaluate whether IL-1β mediates high-output inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in these specialized epithelial cells and characterize gonadotropin and cytokine-regulation of NO. Purified SCs were maintained in serum-free cultures and treated with FSH (100 ng-1 μg/ml) or IL-1β (10 ng/ml) in time-course studies. To determine obligatory intracellular pathways, treatments were conducted with or without activity inhibitors: COX-2 selective (NS-398, 10 μM) or JNK (SP600125, 10 μM) for 1, 3, 6, and 24 h. NOS mRNAs and proteins were evaluated by RT-PCR and Western analysis, respectively. NO and reactive oxygen species were measured by flow cytometry and ELISA. IL-1β transiently induces intracellular NO (30 min) but not reactive oxygen species. Subsequently, iNOS mRNA and protein expression (3-6 h) significantly increased after IL-1β but not FSH stimulation, and in time-dependent manner, markedly increased extracellular NO (24 h, 8-fold). No change in the constitutive endothelial NOS isoform was observed. Inhibition of JNK, but not COX-2, activity inhibits IL-1β-induced iNOS expression and NO production. Such findings suggest that intra- and extracellular NO within the tubule may alert SCs monitoring the microenvironment to an aberrant cytokine, triggering antioxidant and antiinflammatory activities to avoid disruption of spermatogenesis.