Whole body glucoregulation and tissue-specific glucose uptake in a novel Akt substrate of 160 kDa knockout rat model

PLoS One. 2019 Apr 29;14(4):e0216236. doi: 10.1371/journal.pone.0216236. eCollection 2019.

Abstract

Akt substrate of 160 kDa (also called AS160 or TBC1D4) is a Rab GTPase activating protein and key regulator of insulin-stimulated glucose uptake which is expressed by multiple tissues, including skeletal muscle, white adipose tissue (WAT) and the heart. This study introduces a novel rat AS160-knockout (AS160-KO) model that was created using CRISPR/Cas9 technology. We compared male AS160-KO versus wildtype (WT) rats for numerous metabolism-related endpoints. Body mass, body composition, energy expenditure and physical activity did not differ between genotypes. Oral glucose intolerance was detected in AS160-KO versus WT rats (P<0.005). A hyperinsulinemic-euglycemic clamp (HEC) revealed insulin resistance for glucose infusion rate (P<0.05) with unaltered hepatic glucose production in AS160-KO versus WT rats. Genotype-effects on glucose uptake during the HEC: 1) was significantly lower in epitrochlearis (P<0.01) and extensor digitorum longus (P<0.05) of AS160-KO versus WT rats, and tended to be lower for AS160-KO versus WT rats in the soleus (P<0.06) and gastrocnemius (P<0.08); 2) tended to be greater for AS160-KO versus WT rats in white adipose tissue (P = 0.09); and 3) was significantly greater in the heart (P<0.005) of AS160-KO versus WT rats. GLUT4 protein abundance was significantly lower for AS160-KO versus WT rats in each tissue analyzed (P<0.01-0.001) except the gastrocnemius. Ex vivo insulin-stimulated glucose uptake was significantly lower (P<0.001) for AS160-KO versus WT rats in isolated epitrochlearis or soleus. Insulin-stimulated Akt phosphorylation (in vivo or ex vivo) did not differ between genotypes for any tissue tested. Ex vivo AICAR-stimulated glucose uptake by isolated epitrochlearis was significantly lower for AS160-KO versus WT rats (P<0.01) without genotype-induced alteration in AMP-activated protein phosphorylation. This unique AS160-KO rat model, which elucidated striking genotype-related modifications in glucoregulation, will enable future research aimed at understanding AS160's roles in numerous physiological processes in response to various interventions (e.g., diet and/or exercise).

Publication types

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

MeSH terms

  • Adenylate Kinase / metabolism
  • Aminoimidazole Carboxamide / analogs & derivatives
  • Aminoimidazole Carboxamide / pharmacology
  • Animals
  • Body Composition
  • Body Weight
  • Deoxyglucose / metabolism
  • Feeding Behavior
  • GTPase-Activating Proteins / metabolism*
  • Gene Knockout Techniques*
  • Genotype
  • Glucose / metabolism*
  • Glucose Clamp Technique
  • Glucose Tolerance Test
  • Glucose Transporter Type 4 / metabolism
  • Humans
  • Hyperinsulinism / metabolism
  • Insulin / pharmacology
  • Male
  • Models, Animal
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / metabolism
  • Myosin Heavy Chains / metabolism
  • Organ Specificity*
  • Phosphorylation
  • Physical Conditioning, Animal
  • Protein Isoforms / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Rats, Transgenic
  • Ribonucleotides / pharmacology

Substances

  • GTPase-Activating Proteins
  • Glucose Transporter Type 4
  • Insulin
  • Protein Isoforms
  • Ribonucleotides
  • TBC1D4 protein, rat
  • Aminoimidazole Carboxamide
  • Deoxyglucose
  • Proto-Oncogene Proteins c-akt
  • Adenylate Kinase
  • Myosin Heavy Chains
  • AICA ribonucleotide
  • Glucose