METTL3-mediated ANXA2 inhibition confers neuroprotection in ischemic stroke: Evidence from in vivo and in vitro studies.

Given the important role of m6A, the most common and reversible mRNA modification, in the pathogenesis of ischemic stroke, this study investigates the mechanisms of m6A methyltransferase METTL3 in neuronal damage in ischemic stroke. In silico analysis was used to pinpoint the expression of ANXA2, which was verified in clinical peripheral blood samples. SD rats were used for middle cerebral artery occlusion (MCAO) establishment. The experimental data suggested that T lymphocytes were increased in peripheral blood samples of ischemic stroke patients and MCAO rats. The MCAO rats were treated with anti-ANXA2 alone or combined with RP101075 (T lymphocyte infiltration inhibitor), followed by brain injury assessment. Oxygen-glucose deprivation/reoxygenation (OGD/R) was induced in primary cortical neurons, where shRNAs targeting ANXA2 or METTL3, or overexpression plasmids of METTL3 were introduced to verify the regulatory function for METTL3. Inhibition of T lymphocyte migration to the ischemic brain reduced brain injury in MCAO rats and neuronal damage in OGD/R-exposed neurons. Ablation of ANXA2 in T lymphocytes inhibited the migration of T lymphocytes to the ischemic brain and reduced neuronal damage. Mechanistically, METTL3 reduced ANXA2 expression in T lymphocytes through m6A modification and inhibited p38MAPK/MMP-9 pathway activation, exerting protective effects against neuronal damage in ischemic stroke. Overall, this study reveals the neuroprotective effects of METTL3-mediated ANXA2/p38MAPK/MMP-9 inhibition against ischemic stroke.

Changes in the tight junctions of the testis during aging: Role of the p38 MAPK/MMP9 pathway and autophagy in Sertoli cells.

Impaired tight junction (TJ) function and autophagy and the activated p38 mitogen-activated protein kinase (MAPK)/matrix metalloproteinase 9 (MMP9) pathway in Sertoli cells cause spermatogenic disorders. However, it is unclear whether reduced TJ barrier function and autophagy and the activated p38 MAPK/MMP9 pathway in Sertoli cells are closely associated with age-related testicular dysfunction. Thus, we evaluated these changes in Sertoli cells using 6-, 12-, 18-, and 24-month-old Sprague-Dawley rats. The results showed that testicular morphology gradually degenerated, as evidenced by increased exfoliated germ cells, decreased seminiferous tubule diameter and seminiferous epithelium height, and reduced the numbers of spermatogonia, primary spermatocytes and spermatids during the process of aging. In addition, the TJs formed by adjacent Sertoli cells were progressively destroyed accompanied by an abnormal ultrastructure and decreased expression of the TJ proteins zonula occludens-1 (ZO-1), occludin, and claudin-11 with aging. Furthermore, the expression of phosphorylated p38MAPK and MMP-9 in Sertoli cells and testis gradually increased, and the expression of occludin co-localizated with MMP-9 progressively decreased. Meanwhile, autophagy levels also gradually decreased, including decreased autophagic vacuole formation and weak expression of light chain 3 (LC3) and autophagy-related 5 (Atg5) in Sertoli cells. Taken together, our results indicate that aging causes impaired TJ barrier function and degeneration of seminiferous tubules. The mechanism might be related to the activated p38MAPK/MMP9 pathway and inactivated autophagy in Sertoli cells.