A Tbc1d1Ser231Ala-knockin mutation partially impairs AICAR- but not exercise-induced muscle glucose uptake in mice.
TBC1D1 (tre-2/USP6, BUB2, cdc16 domain family member 1) is a Rab GTPase-activating protein (RabGAP) that has been implicated in regulating GLUT4 trafficking. TBC1D1 can be phosphorylated by the AMP-activated protein kinase (AMPK) on Ser231, which consequently interacts with 14-3-3 proteins. Given the key role for AMPK in regulating insulin-independent muscle glucose uptake, we hypothesised that TBC1D1-Ser231phosphorylation and/or 14-3-3 binding may mediate AMPK-governed glucose homeostasis.



Whole-body glucose homeostasis and muscle glucose uptake were assayed in mice bearing a Tbc1d1Ser231Ala-knockin mutation or harbouring skeletal muscle-specific Ampkα1/α2 (also known as Prkaa1/2) double-knockout mutations in response to an AMPK-activating agent, 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR). Exercise-induced muscle glucose uptake and exercise capacity were also determined in the Tbc1d1Ser231Ala-knockin mice.



Skeletal muscle-specific deletion of Ampkα1/a2 in mice prevented AICAR-induced hypoglycaemia and muscle glucose uptake. The Tbc1d1Ser231Ala-knockin mutation also attenuated the glucose-lowering effect of AICAR in mice. Glucose uptake and cell surface GLUT4 content were significantly lower in muscle isolated from the Tbc1d1Ser231Ala-knockin mice upon stimulation with a submaximal dose of AICAR. However, this Tbc1d1Ser231Ala-knockin mutation neither impaired exercise-induced muscle glucose uptake nor affected exercise capacity in mice.



TBC1D1-Ser231phosphorylation and/or 14-3-3 binding partially mediates AMPK-governed glucose homeostasis and muscle glucose uptake in a context-dependent manner.
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China.
Qiaoli
Q
Chen
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China.
Bingxian
B
Xie
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China.
Sangsang
S
Zhu
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China.
Ping
P
Rong
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China.
Yang
Y
Sheng
Nestlé Institute of Health Sciences SA, Campus EPFL, Quartier de l'Innovation, Bâtiment G, Lausanne, Switzerland.
Serge
S
Ducommun
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China.
Liang
L
Chen
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China.
Chao
C
Quan
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China.
Min
M
Li
Nestlé Institute of Health Sciences SA, Campus EPFL, Quartier de l'Innovation, Bâtiment G, Lausanne, Switzerland.
Kei
K
Sakamoto
Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee, Scotland, UK.
Carol
C
MacKintosh
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China. schen6@163.com.|Collaborative Innovation Center of Genetics and Development, Shanghai, China. schen6@163.com.
Shuai
S
Chen
MOE Key Laboratory of Model Animal for Disease Study and State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing Biomedical Research Institute, Nanjing University, Pukou District, Nanjing, 210061, China. wanghy@nicemice.cn.|Collaborative Innovation Center of Genetics and Development, Shanghai, China. wanghy@nicemice.cn.
Hong Yu
HY
Wang
D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism; D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D015444:Exercise / Q000502:physiology*; D020690:GTPase-Activating Proteins / Q000235:genetics*; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D051379:Mice; D018482:Muscle, Skeletal / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D012265:Ribonucleotides / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology
D048948:14-3-3 Proteins; D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D012265:Ribonucleotides; C526441:TBC1D1 protein, human; D000620:Aminoimidazole Carboxamide; C548179:Prkaa1 protein, mouse; C534978:Prkaa2 protein, mouse; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D005947:Glucose
14-3-3; AMPK; Glucose uptake; Phosphorylation; TBC1D1