Sumoylation-deficient phosphoglycerate mutase 2 impairs myogenic differentiation

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Phosphoglycerate mutase 2 (PGAM2) is a crucial glycolytic enzyme in skeletal muscle.
• Mutations in PGAM2 are linked to glycogen storage disease X (GSDX).
• PGAM2 activity is modulated by posttranslational modifications like ubiquitination and acetylation.

Purpose of the Study:

• To investigate the role of sumoylation in regulating PGAM2 activity.
• To determine the impact of PGAM2 sumoylation disruption on cellular functions.
• To explore the link between PGAM2 sumoylation and GSDX.

Main Methods:

• Utilized CRISPR-mediated homologous recombination to create PGAM2 K176R knock-in cells.
• Assessed myogenic differentiation using differentiation and fusion indexes.
• Analyzed glycolytic and mitochondrial function using XF96 Extracellular Flux analyzer.
• Performed RNA sequencing and Gene Ontology analysis.
• Investigated naturally occurring GSDX-linked PGAM2 mutations.

Main Results:

• PGAM2 sumoylation occurs at lysine 49 and lysine 176.
• Mutation of K176 to arginine (PGAM2 K176R) impaired myogenic differentiation and fusion.
• PGAM2 K176R cells showed reduced glycolysis and mitochondrial respiration (OCR, ECAR, PER).
• GSDX-associated mutations (E89A, R90W) reduced PGAM2 sumoylation.
• Downregulated genes in PGAM2 K176R cells were linked to muscle programs.

Conclusions:

• Sumoylation is a critical regulator of PGAM2 activity.
• Disruption of PGAM2 sumoylation impairs muscle cell differentiation and metabolic function.
• PGAM2 sumoylation is implicated in the pathogenesis of PGAM2 mutation-linked diseases like GSDX.