Renal ischemia/reperfusion injury is a main cause of acute kidney injury (AKI) triggering an inflammatory response associated with infiltrating macrophages. Lipocalin-2 (Lcn2) levels correlate positively and protect against renal ischemia/reperfusion injury. However, the mechanisms remain unclear. The aim of study was to investigate the protective mechanisms of Lcn2 on renal ischemia/reperfusion injury. We found that Lcn2 deficiency significantly aggravated renal injury as evidenced by higher serum creatinine, more severe morphological injury, and increased tubular epithelial cell death in mice. We also observed that attenuated autophagy in Lcn2 mice, as autophagy markers LC3 II level was significantly decreased and p62 was increased in the Lcn2 mice after I/R, compared with that of wild type. Mechanistically, we found that recombinant Lcn2 attenuated hypoxia-induced apoptosis in proximal tubule epithelial cells in vitro, and downregulation of HIF-1α blunted Lcn2-induced autophagy and enhanced apoptosis. In addition, the Lcn2 attenuated NF-κb subunit p65 activation under hypoxia conditions. Thus, our findings provide a better understanding of the protective role of Lcn2 in kidney ischemia/reperfusion injury and suggest that Lcn2 may be a promising therapeutic target for treating patients with AKI.

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Stroke is a leading cause of death and disability, but treatment options remain limited. Recent studies have suggested that cerebral ischemia‐induced neurogenesis plays a vital role in post‐stroke repair. Overactivation of AMP ‐activated protein kinase ( AMPK ), a master sensor of energy balance, has been reported to exacerbate neuron apoptosis, but the role of chronic AMPK stimulus in post‐stroke recovery remains unclear. Micro RNA s have emerged as regulators of neurogenesis and have been reported to be involved in neurological function. In this study, we verified that miR‐27b directly targets AMPK and inhibits AMPK expression. In cultured neural stem cells, miR‐27b inhibitor improved proliferation and differentiation via the AMPK signaling pathway, but did not have an obvious effect on cell viability under oxygen and glucose deprivation conditions. In a mouse middle cerebral artery occlusion model, administration of miR‐27b inhibitor significantly enhanced behavioral function recovery and spatial memory. Up‐regulation of neurogenesis was observed both in the subventricular zone and in the hippocampal dentate gyrus. Collectively, our data suggest that miR‐27b inhibition promotes recovery after ischemic stroke by regulating AMPK activity. These findings may facilitate the development of novel therapeutic strategies for stroke.

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