Timely expression of PGAM5 and its cleavage control mitochondrial homeostasis during neurite re-growth after traumatic brain injury

Min-Zong Liang; Ting-Hsuan Lu; Linyi Chen

doi:10.1186/s13578-023-01052-0

Timely expression of PGAM5 and its cleavage control mitochondrial homeostasis during neurite re-growth after traumatic brain injury

Cell Biosci. 2023 May 23;13(1):96. doi: 10.1186/s13578-023-01052-0.

Authors

Min-Zong Liang¹, Ting-Hsuan Lu², Linyi Chen^{3

4}

Affiliations

¹ Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan.
² Department of Medical Science, National Tsing Hua University, Hsinchu, Taiwan.
³ Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan. lchen@life.nthu.edu.tw.
⁴ Department of Medical Science, National Tsing Hua University, Hsinchu, Taiwan. lchen@life.nthu.edu.tw.

Abstract

Background: Patients suffered from severe traumatic brain injury (TBI) have twice the risk of developing into neurodegenerative diseases later in their life. Thus, early intervention is needed not only to treat TBI but also to reduce neurodegenerative diseases in the future. Physiological functions of neurons highly depend on mitochondria. Thus, when mitochondrial integrity is compromised by injury, neurons would initiate a cascade of events to maintain homeostasis of mitochondria. However, what protein senses mitochondrial dysfunction and how mitochondrial homeostasis is maintained during regeneration remains unclear.

Results: We found that TBI-increased transcription of a mitochondrial protein, phosphoglycerate mutase 5 (PGAM5), during acute phase was via topological remodeling of a novel enhancer-promoter interaction. This up-regulated PGAM5 correlated with mitophagy, whereas presenilins-associated rhomboid-like protein (PARL)-dependent PGAM5 cleavage at a later stage of TBI enhanced mitochondrial transcription factor A (TFAM) expression and mitochondrial mass. To test whether PGAM5 cleavage and TFAM expression were sufficient for functional recovery, mitochondrial oxidative phosphorylation uncoupler carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP) was used to uncouple electron transport chain and reduce mitochondrial function. As a result, FCCP triggered PGAM5 cleavage, TFAM expression and recovery of motor function deficits of CCI mice.

Conclusions: Findings from this study implicate that PGAM5 may act as a mitochondrial sensor for brain injury to activate its own transcription at acute phase, serving to remove damaged mitochondria through mitophagy. Subsequently, PGAM5 is cleaved by PARL, and TFAM expression is increased for mitochondrial biogenesis at a later stage after TBI. Taken together, this study concludes that timely regulation of PGAM5 expression and its own cleavage are required for neurite re-growth and functional recovery.

Keywords: Epigenetic regulation; Mitochondrial homeostasis; Neurite re-growth; PGAM5; Traumatic brain injury.

Abstract

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