Biochemical and genetic evaluation of the role of AMP-activated protein kinase in polysaccharide storage myopathy in Quarter Horses.

The research is centered on assessing if alterations at a biochemical or genetic level in the AMP-activated protein kinase (AMPK) contribute to the development of polysaccharide storage myopathy (PSSM) in Quarter Horses. The results of the study reveal no evidence to suggest that AMPK plays a causative role in PSSM among the horses studied.

Methods Employed in the Study

The researchers utilized several methods to evaluate the role of AMPK in PSSM:

• In order to measure both basal and maximal AMP-activated protein kinase activities, an established peptide phosphotransfer assay was used on muscle biopsy samples taken from 6 PSSM-affected horses and 6 control horses.
• In 24 PSSM-affected and 24 control horses, the researchers used genotyping with a fluorescent DNA fragment analyzer after identifying microsatellite markers from the chromosomal locations of all 7 AMPK subunit genes.
• Alleles of two AMPK gamma subunit genes were genotyped through DNA sequencing.
• DNA marker allele frequencies that were in or near the AMPK subunit genes were measured using isolated genomic DNA.

Findings of the Study

The findings highly suggest that AMPK does not contribute to the causation of PSSM in Quarter Horses:

• No differences were detected in basal or maximal muscle AMP-activated protein kinase enzyme activities between PSSM-affected and control horses.
• Similarly, there were no differences in allele frequencies for the microsatellite markers found near any of the AMPK subunit genes between the PSSM-affected and control horses.
• Additionally, both previously known and newly identified alleles of the two equine AMP-activated protein kinase gamma subunit genes showed no association with PSSM.

Conclusions of the Study

Given the results of their research, the study concludes that:

• There isn’t sufficient evidence to suggest that the AMP-activated protein kinase has a causative role in the development of polysaccharide storage myopathy in the Quarter Horses studied.