Reduced Stability and pH-Dependent Activity of a Common Obesity-Linked PCSK1 Polymorphism, N221D.

Abstract

Common mutations in the human prohormone convertase (PC)1/3 gene (PCKSI) are linked to increased risk of obesity. Previous work has shown that the rs6232 single-nucleotide polymorphism (N221D) results in slightly decreased activity, although whether this decrease underlies obesity risk is not clear. We observed significantly decreased activity of the N221D PC1/3 enzyme at the pH of the trans-Golgi network; at this pH, the mutant enzyme was less stable than wild-type enzyme. Recombinant N221D PC1/3 also showed enhanced susceptibility to heat stress. Enhanced susceptibility to tunicamycin-induced endoplasmic reticulum stress was observed in AtT-20/PC2 cell clones in which murine PC1/3 was replaced by human N221D PC1/3, as compared with wild-type human PC1/3. However, N221D PC1/3-expressing AtT-20/PC2 clones processed proopiomelanocortin to α-MSH similarly to wild-type PC1/3. We also generated a CRISPR-edited mouse line expressing the N221D mutation in the PCKSI gene. When homozygous N221D mice were fed either a standard or a high-fat diet, we found no increase in body weight compared with their wild-type sibling controls. Sexual dimorphism was observed in pituitary ACTH for both genotypes, with females exhibiting lower levels of pituitary ACTH. In contrast, hypothalamic α-MSH content for both genotypes was higher in females compared with males. Hypothalamic corticotropin-like intermediate peptide content was higher in wild-type females compared with wild-type, but not N221D, males. Taken together, these data suggest that the increased obesity risk linked to the N221D allele in humans may be due in part to PC1/3-induced loss of resilience to stressors rather than strictly to decreased enzymatic activity on peptide precursors.

• Authors: Timothy S Jarvela, Manita Shakya, Tomas Bachor, Anne White, Malcolm J Low, Iris Lindberg
• Journal: Endocrinology (Endocrinology) Vol. 160 Issue 11 Pg. 2630-2645 (11 01 2019) ISSN: 1945-7170 [Electronic] United States
• PMID: 31504391 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2019 Endocrine Society.

Chemical References

• Neuropeptide Y
• alpha-MSH
• Pro-Opiomelanocortin
• PCSK1 protein, human
• Proprotein Convertase 1

Topics

• Animals
• Endoplasmic Reticulum Stress
• Enzyme Stability
• Female
• Glucose Intolerance
• Humans
• Hydrogen-Ion Concentration
• Hypothalamus (metabolism)
• Male
• Mice
• Neuropeptide Y (metabolism)
• Obesity (genetics)
• Pituitary Gland (metabolism)
• Polymorphism, Single Nucleotide
• Pro-Opiomelanocortin (metabolism)
• Proprotein Convertase 1 (genetics, metabolism)
• Sex Characteristics
• alpha-MSH (metabolism)