Defects in pancreatic development and glucose metabolism in SMN-depleted mice independent of canonical spinal muscular atrophy neuromuscular pathology

Melissa Bowerman, John-Paul Michalski, Ariane Beauvais, Lyndsay M. Murray, Yves DeRepentigny, Rashmi Kothary*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Spinal muscular atrophy (SMA) is characterized by motor neuron loss, caused by mutations or deletions in the ubiquitously expressed survival motor neuron 1 (SMN1) gene. We recently identified a novel role for Smn protein in glucose metabolism and pancreatic development in both an intermediate SMA mouse model (Smn(2B/-)) and type I SMA patients. In the present study, we sought to determine if the observed metabolic and pancreatic defects are SMA-dependent. We employed a line of heterozygous Smn-depleted mice (Smn(+/-)) that lack the hallmark SMA neuromuscular pathology and overt phenotype. At 1 month of age, pancreatic/metabolic function of Smn(+/-)mice is indistinguishable from wild type. However, when metabolically challenged with a high-fat diet, Smn(+/-)mice display abnormal localization of glucagon-producing alpha-cells within the pancreatic islets and increased hepatic insulin and glucagon sensitivity, through increased p-AKT and p-CREB, respectively. Further, aging results in weight gain, an increased number of insulin-producing beta cells, hyperinsulinemia and increased hepatic glucagon sensitivity in Smn(+/-)mice. Our study uncovers and highlights an important function of Smn protein in pancreatic islet development and glucose metabolism, independent of canonical SMA pathology. These findings suggest that carriers of SMN1 mutations and/or deletions may be at an increased risk of developing pancreatic and glucose metabolism defects, as even small depletions in Smn protein may be a risk factor for diet- and age-dependent development of metabolic disorders.

Original languageEnglish
Pages (from-to)3432-3444
Number of pages13
JournalHuman Molecular Genetics
Volume23
Issue number13
DOIs
Publication statusPublished - Jul 2014

Keywords

  • SURVIVAL MOTOR-NEURON
  • GENE-PRODUCT
  • MOUSE MODEL
  • TRANSCRIPTION FACTORS
  • INSULIN-RESISTANCE
  • CELL HYPERPLASIA
  • CARDIAC DEFECTS
  • MESSENGER-RNA
  • PROTEIN
  • CREB

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