title: Exercise alleviates lipid-induced insulin resistance in human skeletal muscle-signaling interaction at the level of TBC1 domain family member 4.
abstract: Excess lipid availability causes insulin resistance. We examined the effect of acute exercise on lipid-induced insulin resistance and TBC1 domain family member 1/4 (TBCD1/4)-related signaling in skeletal muscle. In eight healthy young male subjects, 1 h of one-legged knee-extensor exercise was followed by 7 h of saline or intralipid infusion. During the last 2 h, a hyperinsulinemic-euglycemic clamp was performed. Femoral catheterization and analysis of biopsy specimens enabled measurements of leg substrate balance and muscle signaling. Each subject underwent two experimental trials, differing only by saline or intralipid infusion. Glucose infusion rate and leg glucose uptake was decreased by intralipid. Insulin-stimulated glucose uptake was higher in the prior exercised leg in the saline and the lipid trials. In the lipid trial, prior exercise normalized insulin-stimulated glucose uptake to the level observed in the resting control leg in the saline trial. Insulin increased phosphorylation of TBC1D1/4. Whereas prior exercise enhanced TBC1D4 phosphorylation on all investigated sites compared with the rested leg, intralipid impaired TBC1D4 S341 phosphorylation compared with the control trial. Intralipid enhanced pyruvate dehydrogenase (PDH) phosphorylation and lactate release. Prior exercise led to higher PDH phosphorylation and activation of glycogen synthase compared with resting control. In conclusion, lipid-induced insulin resistance in skeletal muscle was associated with impaired TBC1D4 S341 and elevated PDH phosphorylation. The prophylactic effect of exercise on lipid-induced insulin resistance may involve augmented TBC1D4 signaling and glycogen synthase activation.
authors.affiliation: Department of Exercise and Sport Sciences, Molecular Physiology Group, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Pehmøller
authors.forename: Nina
authors.initials: N
authors.lastname: Brandt
authors.forename: Jesper B
authors.initials: JB
authors.lastname: Birk
authors.forename: Louise D
authors.initials: LD
authors.lastname: Høeg
authors.forename: Kim A
authors.initials: KA
authors.lastname: Sjøberg
authors.forename: Laurie J
authors.initials: LJ
authors.lastname: Goodyear
authors.forename: Bente
authors.initials: B
authors.lastname: Kiens
authors.forename: Erik A
authors.initials: EA
authors.lastname: Richter
authors.forename: Jørgen F P
authors.initials: JF
authors.lastname: Wojtaszewski
mesh_terms: D000328:Adult; D004655:Emulsions / Q000009:adverse effects; D015444:Exercise; D005217:Fat Emulsions, Intravenous / Q000009:adverse effects*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D006006:Glycogen Synthase / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D061389:Insulin, Regular, Pork; D019344:Lactic Acid / Q000378:metabolism; D007866:Leg; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010743:Phospholipids / Q000009:adverse effects*; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013024:Soybean Oil / Q000009:adverse effects*
chemical_list: D004655:Emulsions; D005217:Fat Emulsions, Intravenous; D020690:GTPase-Activating Proteins; D007004:Hypoglycemic Agents; D007328:Insulin; D061389:Insulin, Regular, Pork; D010743:Phospholipids; D011768:Pyruvate Dehydrogenase Complex; C526441:TBC1D1 protein, human; C518767:TBC1D4 protein, human; C545823:soybean oil, phospholipid emulsion; D019344:Lactic Acid; D013024:Soybean Oil; C000006:insulin, neutral; D006006:Glycogen Synthase; D005947:Glucose