The last enzyme of the de novo purine synthesis pathway 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (ATIC) plays a central role in insulin signaling and the Golgi/endosomes protein network

Mol Cell Proteomics. 2015 Apr;14(4):1079-92. doi: 10.1074/mcp.M114.047159. Epub 2015 Feb 16.


Insulin is internalized with its cognate receptor into the endosomal apparatus rapidly after binding to hepatocytes. We performed a bioinformatic screen of Golgi/endosome hepatic protein fractions and found that ATIC, which is a rate-limiting enzyme in the de novo purine biosynthesis pathway, and PTPLAD1 are associated with insulin receptor (IR) internalization. The IR interactome (IRGEN) connects ATIC to AMPK within the Golgi/endosome protein network (GEN). Forty-five percent of the IR Golgi/endosome protein network have common heritable variants associated with type 2 diabetes, including ATIC and AMPK. We show that PTPLAD1 and AMPK are rapidly compartmentalized within the plasma membrane (PM) and Golgi/endosome fractions after insulin stimulation and that ATIC later accumulates in the Golgi/endosome fraction. Using an in vitro reconstitution system and siRNA-mediated partial knockdown of ATIC and PTPLAD1 in HEK293 cells, we show that both ATIC and PTPLAD1 affect IR tyrosine phosphorylation and endocytosis. We further show that insulin stimulation and ATIC knockdown readily increase the level of AMPK-Thr172 phosphorylation in IR complexes. We observed that IR internalization was markedly decreased after AMPKα2 knockdown, and treatment with the ATIC substrate AICAR, which is an allosteric activator of AMPK, increased IR endocytosis in cultured cells and in the liver. These results suggest the presence of a signaling mechanism that senses adenylate synthesis, ATP levels, and IR activation states and that acts in regulating IR autophosphorylation and endocytosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylate Kinase / metabolism
  • Aminoimidazole Carboxamide / analogs & derivatives
  • Aminoimidazole Carboxamide / pharmacology
  • Animals
  • Biosynthetic Pathways* / drug effects
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Computational Biology
  • Endocytosis / drug effects
  • Endosomes / drug effects
  • Endosomes / metabolism*
  • Female
  • Gene Knockdown Techniques
  • Golgi Apparatus / drug effects
  • Golgi Apparatus / metabolism*
  • HEK293 Cells
  • Humans
  • Hydro-Lyases
  • Insulin / metabolism*
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Kinetics
  • Liver / drug effects
  • Liver / metabolism
  • Mass Spectrometry
  • Nucleotide Deaminases / metabolism*
  • Phosphorylation / drug effects
  • Proteomics
  • Purines / biosynthesis*
  • Rats, Sprague-Dawley
  • Receptor, Insulin / metabolism
  • Ribonucleotides / pharmacology
  • Signal Transduction* / drug effects
  • Sus scrofa


  • Insulin
  • Intracellular Signaling Peptides and Proteins
  • Purines
  • Ribonucleotides
  • Aminoimidazole Carboxamide
  • Receptor, Insulin
  • Adenylate Kinase
  • Nucleotide Deaminases
  • IMP cyclohydrolase
  • HACD3 protein, human
  • Hydro-Lyases
  • AICA ribonucleotide
  • purine