Deciphering the neuroprotective mechanisms of RACK1 in cerebral ischemia‐reperfusion injury: Pioneering insights into mitochondrial autophagy and the PINK1/Parkin axis

 Something was described here, but further research will be needed to see if any interventions can be created to protect against this neural damage.

Deciphering the neuroprotective mechanisms of RACK1 in cerebral ischemia‐reperfusion injury: Pioneering insights into mitochondrial autophagy and the PINK1/Parkin axis

Lanqing Zhao, ¹ Yu Chen, ² Hongxi Li, ³ Xiaoxu Ding, ² and Jinwei Li ⁴

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Abstract

Introduction

Cerebral ischemia‐reperfusion injury (CIRI) is a common and debilitating complication of cerebrovascular diseases such as stroke, characterized by mitochondrial dysfunction and cell apoptosis. Unraveling the molecular mechanisms behind these processes is essential for developing effective CIRI treatments. This study investigates the role of RACK1 (receptor for activated C kinase 1) in CIRI and its impact on mitochondrial autophagy.

Methods

We utilized high‐throughput transcriptome sequencing and weighted gene co‐expression network analysis (WGCNA) to identify core genes associated with CIRI. In vitro experiments used human neuroblastoma SK‐N‐SH cells subjected to oxygen and glucose deprivation (OGD) to simulate ischemia, followed by reperfusion (OGD/R). RACK1 knockout cells were created using CRISPR/Cas9 technology, and cell viability, apoptosis, and mitochondrial function were assessed. In vivo experiments involved middle cerebral artery occlusion/reperfusion (MCAO/R) surgery in rats, evaluating neurological function and cell apoptosis.

Results

Our findings revealed that RACK1 expression increases during CIRI and is protective by regulating mitochondrial autophagy through the PINK1/Parkin pathway. In vitro, RACK1 knockout exacerbated cell apoptosis, while overexpression of RACK1 reversed this process, enhancing mitochondrial function. In vivo, RACK1 overexpression reduced cerebral infarct volume and improved neurological deficits. The regulatory role of RACK1 depended on the PINK1/Parkin pathway, with RACK1 knockout inhibiting PINK1 and Parkin expression, while RACK1 overexpression restored them.

Conclusion

This study demonstrates that RACK1 safeguards against neural damage in CIRI by promoting mitochondrial autophagy through the PINK1/Parkin pathway. These findings offer crucial insights into the regulation of mitochondrial autophagy and cell apoptosis by RACK1, providing a promising foundation for future CIRI treatments.

Keywords: cell apoptosis, cerebral ischemia‐reperfusion injury, mitochondrial autophagy, mitochondrial function, neuroprotection, PINK/Parkin pathway, RACK1

This study reveals the key role of RACK1 in CIRI. The study finds that RACK1 regulates mitochondrial function and autophagy. The study confirms the centrality of the PINK1/Parkin pathway. The study offers new strategies for treating CIRI. The study provides comprehensive in vitro and in vivo evidence.

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1. INTRODUCTION

Cerebral ischemic vascular disease ranks as the second leading cause of death in humans. Restoring blood supply to the ischemic area is crucial in treating such diseases; however, reperfusion often leads to secondary brain damage, clinically known as cerebral ischemia‐reperfusion injury (CIRI). ¹ The occurrence of CIRI can result in further damage to the neurocytes in the ischemic area and worsen patients' clinical outcomes. ² Yet, the pathological mechanism of CIRI remains incompletely understood at present. ³ The global incidence of stroke and its concomitant complications, such as CIRI, are on the rise in tandem with the aging global population. These increasing occurrences add significant economic and psychological strain on healthcare infrastructures and the families of affected individuals. ⁴

CIRI involves complex pathological processes, such as energy disruption, intracellular calcium homeostasis loss, and cellular acidosis. ⁵ Recent studies have indicated a close association between CIRI and mitochondrial dysfunction. ⁶ The impairment of mitochondrial function under ischemic conditions leads to an inadequate cellular energy supply, escalating cell death. ⁷ Reperfusion exacerbates this by promoting the generation of oxygen free radicals, further damaging mitochondria and propelling cell apoptosis. ^{8 , 9}

The role of mitophagy, the selective degradation of dysfunctional mitochondria, is receiving increasing focus in the study of CIRI. ¹⁰ This process is critical for removing damaged mitochondria, maintaining cellular function, and proving particularly vital under stress conditions such as ischemia and hypoxia. ^{11 , 12} The PINK1/Parkin pathway is a core player in mitophagy, spearheading the elimination of damaged mitochondria. ¹³

Nonetheless, the molecular intricacies of mitophagy in CIRI are not fully unraveled. RACK1 (receptor for activated C kinase 1) is a multifunctional protein widely distributed within cells, associated with numerous cellular signaling pathways. ^{14 , 15} Additionally, studies have indicated that RACK1 protects against secondary brain injury. ¹⁶ Emerging evidence suggests a potential relationship between RACK1 and mitochondrial autophagy within the context of the PINK1/Parkin pathway. ^{14 , 15 , 17} This study endeavors to intensively explore the functional role of RACK1 in CIRI and its regulatory influence on mitochondrial autophagy. Unveiling these molecular mechanisms can pave the way for identifying innovative targets for CIRI treatment, thereby enhancing patient outcomes and life quality.

In summary, an in‐depth analysis of the role of RACK1 in mitochondrial autophagy within CIRI could unravel novel molecular targets, significantly contributing to the development of advanced therapeutic approaches and positively impacting patient care and prognosis.