title: Rapid activation of Akt2 is sufficient to stimulate GLUT4 translocation in 3T3-L1 adipocytes.
abstract: The serine/threonine kinase Akt2 has been implicated in insulin-regulated glucose uptake into muscle and fat cells by promoting the translocation of glucose transporter 4 (GLUT4) to the cell surface. However, it remains unclear whether activation of Akt2 is sufficient since a role for alternate signaling pathways has been proposed. Here we have engineered 3T3-L1 adipocytes to express a rapidly inducible Akt2 system based on drug-inducible heterodimerization. Addition of the dimerizer rapalog resulted in activation of Akt2 within 5 min, concomitant with phosphorylation of the Akt substrates AS160 and GSK3. Comparison with insulin stimulation revealed that the level of Akt2 activity observed with rapalog was within the physiological range, reducing the likelihood of off-target effects. Transient activation of Akt2 also increased glucose transport and GLUT4 translocation to the plasma membrane. These results show that activation of Akt2 is sufficient to stimulate GLUT4 translocation in 3T3-L1 adipocytes to an extent similar to insulin.
authors.affiliation: Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Ng
authors.forename: Georg
authors.initials: G
authors.lastname: Ramm
authors.forename: Jamie A
authors.initials: JA
authors.lastname: Lopez
authors.forename: David E
authors.initials: DE
authors.lastname: James
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D010122:Cystinyl Aminopeptidase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism; D051379:Mice; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D020123:Sirolimus / Q000031:analogs & derivatives / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C528734:GLUT4 enhancer factor, mouse; D014157:Transcription Factors; C494922:Akt2 protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase; D005947:Glucose; D020123:Sirolimus