In vivo glucoregulation and tissue-specific glucose uptake in female Akt substrate 160 kDa knockout rats

PLoS One. 2020 Feb 13;15(2):e0223340. doi: 10.1371/journal.pone.0223340. eCollection 2020.

Abstract

The Rab GTPase activating protein known as Akt substrate of 160 kDa (AS160 or TBC1D4) regulates insulin-stimulated glucose uptake in skeletal muscle, the heart, and white adipose tissue (WAT). A novel rat AS160-knockout (AS160-KO) was created with CRISPR/Cas9 technology. Because female AS160-KO versus wild type (WT) rats had not been previously evaluated, the primary objective of this study was to compare female AS160-KO rats with WT controls for multiple, important metabolism-related endpoints. Body mass and composition, physical activity, and energy expenditure were not different between genotypes. AS160-KO versus WT rats were glucose intolerant based on an oral glucose tolerance test (P<0.001) and insulin resistant based on a hyperinsulinemic-euglycemic clamp (HEC; P<0.001). Tissue glucose uptake during the HEC of female AS160-KO versus WT rats was: 1) significantly lower in epitrochlearis (P<0.05) and extensor digitorum longus (EDL; P<0.01) muscles of AS160-KO compared to WT rats; 2) not different in soleus, gastrocnemius or WAT; and 3) ~3-fold greater in the heart (P<0.05). GLUT4 protein content was reduced in AS160-KO versus WT rats in the epitrochlearis (P<0.05), EDL (P<0.05), gastrocnemius (P<0.05), soleus (P<0.05), WAT (P<0.05), and the heart (P<0.005). Insulin-stimulated glucose uptake by isolated epitrochlearis and soleus muscles was lower (P<0.001) in AS160-KO versus WT rats. Akt phosphorylation of insulin-stimulated tissues was not different between the genotypes. A secondary objective was to probe processes that might account for the genotype-related increase in myocardial glucose uptake, including glucose transporter protein abundance (GLUT1, GLUT4, GLUT8, SGLT1), hexokinase II protein abundance, and stimulation of the AMP-activated protein kinase (AMPK) pathway. None of these parameters differed between genotypes. Metabolic phenotyping in the current study revealed AS160 deficiency produced a profound glucoregulatory phenotype in female AS160-KO rats that was strikingly similar to the results previously reported in male AS160-KO rats.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Animals
  • Disease Models, Animal
  • Female
  • GTPase-Activating Proteins / deficiency*
  • GTPase-Activating Proteins / genetics
  • Gluconeogenesis / genetics*
  • Glucose / metabolism*
  • Glucose Clamp Technique
  • Glucose Tolerance Test
  • Glucose Transport Proteins, Facilitative / metabolism
  • Humans
  • Insulin Resistance / genetics*
  • Liver / metabolism
  • Muscle, Skeletal / metabolism*
  • Physical Conditioning, Animal
  • Rats
  • Rats, Transgenic
  • Rats, Wistar
  • Signal Transduction

Substances

  • GTPase-Activating Proteins
  • Glucose Transport Proteins, Facilitative
  • Slc2a8 protein, rat
  • TBC1D4 protein, rat
  • AMP-Activated Protein Kinases
  • Glucose