Correction: MicroRNA-221 inhibits autophagy and promotes heart failure by modulating the p27/CDK2/mTOR axis

Inhibition of miR-221-3p promotes axonal regeneration and repair of primary sensory neurons via regulating p27 expression

This study aimed to explore the key microRNA (miRNA) playing a vital role in axonal regeneration with a hostile microenvironment after spinal cord injury. Based on the theory that sciatic nerve conditioning injury (SNCI) could promote the repair of the injured dorsal column. Differentially expressed miRNAs were screened according to the microarray, revealing that 47 known miRNAs were differentially expressed after injury and perhaps involved in nerve regeneration. Among the 47 miRNAs, the expression of miR-221-3p decreased sharply in the SNCI group compared with the simple dorsal column lesion (SDCL) group. Subsequently, it was confirmed that p27 was the target gene of miR-221-3p from luciferase reporter assay. Further, we found that inhibition of miR-221-3p expression could specifically target p27 to upregulate the expression of growth-associated protein 43 (GAP-43), α-tubulin acetyltransferase (α-TAT1) together with α-tubulin, and advance the regeneration of dorsal root ganglion (DRG) neuronal axons. Chondroitin sulfate proteoglycans (CSPGs) are the main components of glial scar, which can hinder the extension and growth of damaged neuronal axons. After CSPGs were used in this study, the results demonstrated that restrained miR-221-3p expression also via p27 promoted the upregulation of GAP-43, α-TAT1, and α-tubulin and enhanced the axonal growth of DRG neurons. Hence, miR-221-3p could contribute significantly to the regeneration of DRG neurons by specifically regulating p27 in the p27/CDK2/GAP-43 and p27/α-TAT1/α-tubulin pathways even in the inhibitory environment with CSPGs.

Autophagy in striated muscle diseases

Impaired biomolecules and cellular organelles are gradually built up during the development and aging of organisms, and this deteriorating process is expedited under stress conditions. As a major lysosome-mediated catabolic process, autophagy has evolved to eradicate these damaged cellular components and recycle nutrients to restore cellular homeostasis and fitness. The autophagic activities are altered under various disease conditions such as ischemia-reperfusion cardiac injury, sarcopenia, and genetic myopathies, which impact multiple cellular processes related to cellular growth and survival in cardiac and skeletal muscles. Thus, autophagy has been the focus for therapeutic development to treat these muscle diseases. To develop the specific and effective interventions targeting autophagy, it is essential to understand the molecular mechanisms by which autophagy is altered in heart and skeletal muscle disorders. Herein, we summarize how autophagy alterations are linked to cardiac and skeletal muscle defects and how these alterations occur. We further discuss potential pharmacological and genetic interventions to regulate autophagy activities and their applications in cardiac and skeletal muscle diseases.

Self-eating and Heart: The Emerging Roles of Autophagy in Calcific Aortic Valve Disease

Autophagy is a self-degradative pathway by which subcellular elements are broken down intracellularly to maintain cellular homeostasis. Cardiac autophagy commonly decreases with aging and is accompanied by the accumulation of misfolded proteins and dysfunctional organelles, which are undesirable to the cell. Reduction of autophagy over time leads to aging-related cardiac dysfunction and is inversely related to longevity. However, despite the increasing interest in autophagy in cardiac diseases and aging, the process remains an undervalued and disregarded object in calcific valvular disease. Neither the nature through which autophagy is triggered nor the interplay between autophagic machinery and targeted molecules during aortic valve calcification are fully understood. Recently, the upregulation of autophagy has been shown to result in cardioprotective effects against cell death as well as its origin. Here, we review the evidence that shows how autophagy can be both beneficial and detrimental as it pertains to aortic valve calcification in the heart.