Possible involvement of a MEG3-miR-21-SPRY1-NF-kB feedback loop in spermatogenic cells proliferation, autophagy and apoptosis

Non-obstructive azoospermia (NOA) is the most incurable male infertility with complex etiology. The molecular mechanism that determines the amount of spermatogenesis in NOA patients is still unclear. LncRNAs have been verified to associate with the regulation of spermatogenesis. However, the specific function and molecular mechanism remain to be confirmed. We use RNA-seq analysis for preliminary screening of different lncRNAs between NOA and normal male and find that MEG3 was upregulated in NOA testicular tissues and inhibit cell proliferation and promote cell autophagy and apoptosis in vitro and vivo. Through RNA immunoprecipitation (RIP), biotin pull-down assays and Dual Luciferase Reporter assays, MEG3 is proved to act as competing endogenous RNA of miR-21 and thus influence the SPRY1/ERK/mTOR signal pathway. In addition, SPRY1 positively regulates MEG3 through SPRY1/NF-κB/MEG3 feedback loop. These findings firstly demonstrate that LncRNA MEG3-miR-21-SPRY1-NF-κB acts as a new feedback loop leading to the occurrence of azoospermia through inhibiting the proliferation, promoting autophagy and apoptosis of spermatogenic cells, which provides a new target and theoretical basis for diagnosis and treatment of non-obstructive azoospermia.