Isoform-specific regulation of Akt signaling by the endosomal protein WDFY2.
Recent work has led to the identification of novel endocytic compartments with functional roles in both protein trafficking and growth factor signal transduction. The phosphatidylinositol 3-phosphate binding, FYVE domain-containing protein WDFY2 is localized to a distinct subset of early endosomes, which are localized close to the plasma membrane. Here, we find that the serine/threonine kinase Akt interacts with these endosomes in an isoform-specific manner. Using quantitative fluorescence microscopy we demonstrate specific co-localization of WDFY2 with endogenous Akt2, but not Akt1. Moreover, depletion of WDFY2 leads to impaired phosphorylation of Akt in response to insulin due to isoform specific reduction of Akt2, but not Akt1, protein levels, and to a marked reduction in the insulin-stimulated phosphorylation of numerous Akt substrates. This is accompanied by an impairment in insulin-stimulated glucose transport and, after prolonged silencing, a reduction in the level of expression of adipogenic genes. We propose that WDFY2-enriched endosomes serve as a scaffold that enables specificity of insulin signaling through Akt2.
Walz
Helena A
HA
Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
Shi
Xiarong
X
Chouinard
My
M
Bue
Catherine A
CA
Navaroli
Deanna M
DM
Hayakawa
Akira
A
Zhou
Qiong L
QL
Nadler
Jonathan
J
Leonard
Deborah M
DM
Corvera
Silvia
S
D041721:3T3-L1 Cells; D000818:Animals; D001692:Biological Transport; D015153:Blotting, Western; D002352:Carrier Proteins / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D008856:Microscopy, Fluorescence; D010766:Phosphorylation; D020033:Protein Isoforms; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques
D002352:Carrier Proteins; D007004:Hypoglycemic Agents; D007328:Insulin; C514055:ProF protein, mouse; D020033:Protein Isoforms; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C514862:Akt1 protein, mouse; C494922:Akt2 protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D005947:Glucose