Proceedings of The Physiological Society

Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCA219

Poster Communications

Different postnatal maturation of AMP-activated protein kinase in skeletal muscle in obesity-prone and obesity-resistant mice

J. Hansikova1, P. Kucharikova1, P. Janovska1, J. Kopecky1

1. Dept. of Adipose Tissue Biology, Institute of Physiology CAS, Prague, Czech Republic.

AMP-activated protein kinase (AMPK) is a multisubunit protein, which plays a key role in control of skeletal muscle metabolism. Little is known about changes in AMPK subunits expression and AMPK activity in skeletal muscle during the early postnatal development, between birth and weaning. The aims of this study were to (i) characterize the activity and protein level of AMPKα1 and AMPKα2 isoforms, and expression of the genes encoding AMPK catalytic subunits in murine skeletal muscle during postnatal development; and (ii) to assess influence of gender and genetic background of mice on AMPK developmental changes. Male (M) and female (F) pups of the obesity-prone C57BL/6 (B/6) mice and obesity-resistant A/J mice were born and maintained at 30 °C. Mice were killed by cervical dislocation at the age of 5, 10, 15, 20 and 28 days (D) after birth. Gastrocnemius muscles were collected by freeze-clamping. AMPK activity (n=6 in each age, gender and strain group) was determined using AMARA peptide substrate (1). Protein levels were assessed by Western blot method using antibody against AMPKα1 and AMPKα2 subunits only at 15D and 28D (n=4). Gene expression was assessed by quantitative PCR (n=5). Values are means ± S.E.M. Evaluation of data was performed by ANOVA and considered as significant when p<0.05. At 10D, the activity of AMPKα1 was significantly higher in comparison with the AMPKα2 activity in all tested groups (A/J F ~1.9-fold; A/J M ~3.3-fold; B/6 F ~2.6-fold; B/6 M ~3.7-fold). Between 10D and 28D, the AMPKα1 activity decreased in mice of both strains except for A/J F (A/J M ~2-fold; B/6 M ~2.6-fold; B/6 F ~3.7-fold). In A/J mice at 28D, activity of AMPKα2 was higher than that of AMPKα1 (A/J F ~1.4-fold; A/J M ~1.6-fold). Total activity of AMPK (α1+α2) in B/6 mice decreased significantly between 10D and 28D (B/6 F ~1.9-fold; B6 M ~ 1.5-fold) but it stayed constant in A/J mice. Protein level of AMPKα1 decreased between 15D and 28D, but significantly only in B6 F mice (B/6 F ~2.4-fold). Expression of AMPKα1 gene was constant in both A/J and B/6 mice. Expression of AMPKα2 gene significantly increased between 5D and 28D in both strains (A/J F ~3.9-fold; A/J M ~4.5-fold; B/6 F ~5.7-fold; B/6 M ~4.8-fold). Strain-specific changes in AMPK activity in murine skeletal muscle were observed. While in the obesity-resistant A/J mice the activity stayed constant, it declined in the obesity-prone B/6 mice. Developmental changes in total AMPK activity are primarily represent by the activity and protein level of AMPKα1 isoform. However changes in activity and protein level are not corresponding to AMPKα1 gene expression. Changes in AMPK activity in skeletal muscle during early postnatal development may affect propensity to obesity in adulthood, depending on the genetic background of the mice.

Where applicable, experiments conform with Society ethical requirements