The pharmacological regulation of cellular mitophagy.
Georgakopoulos Nikolaos D,Wells Geoff,Campanella Michelangelo
Nature chemical biology
Small molecules are pharmacological tools of considerable value for dissecting complex biological processes and identifying potential therapeutic interventions. Recently, the cellular quality-control process of mitophagy has attracted considerable research interest; however, the limited availability of suitable chemical probes has restricted our understanding of the molecular mechanisms involved. Current approaches to initiate mitophagy include acute dissipation of the mitochondrial membrane potential (ΔΨ) by mitochondrial uncouplers (for example, FCCP/CCCP) and the use of antimycin A and oligomycin to impair respiration. Both approaches impair mitochondrial homeostasis and therefore limit the scope for dissection of subtle, bioenergy-related regulatory phenomena. Recently, novel mitophagy activators acting independently of the respiration collapse have been reported, offering new opportunities to understand the process and potential for therapeutic exploitation. We have summarized the current status of mitophagy modulators and analyzed the available chemical tools, commenting on their advantages, limitations and current applications.
Schwann-Cell Autophagy, Functional Recovery, and Scar Reduction After Peripheral Nerve Repair.
Ko Po-Yen,Yang Cheng-Chang,Kuo Yao-Lung,Su Fong-Chin,Hsu Tai-I,Tu Yuan-Kun,Jou I-Ming
Journal of molecular neuroscience : MN
The functional outcome after peripheral nerve repair is often unpredictable for many reasons, e.g., the severity of neuronal death and scarring. Axonal degeneration significantly affects outcomes. Post-injury axonal degeneration in peripheral nerves is accompanied by myelin degradation initiated by Schwann cells (SCs), which activate autophagy, a ubiquitous cytoprotective process essential for degrading and recycling cellular constituents. Scar formation occurs concomitantly with nerve insult and axonal degeneration. The association between SC autophagy and the mechanisms of nerve scar formation is still unknown. A rat model of peripheral nerve lesions induced by sciatic nerve transection injuries was used to examine the function of autophagy in fibrosis reduction during the early phase of nerve repair. Rats were treated with rapamycin (autophagy inducer) or 3-methyladenine (autophagy inhibitor). One week after the nerve damage, fibrosis was potently inhibited in rapamycin-treated rats and, based on gait analysis, yielded a better functional outcome. Immunohistochemistry showed that the autophagic activity of SCs and the accumulation of neurofilaments were upregulated in rapamycin-treated rats. A deficiency of SC autophagic activity might be an early event in nerve scar formation, and modulating autophagy might be a powerful pharmacological approach for improving functional outcomes.