title: Regulation of phosphoglucomutase 1 phosphorylation and activity by a signaling kinase.
abstract: We have identified a novel mechanism of cross-talk between cell signaling and metabolic pathways, whereby the signaling kinase p21-activated kinase 1 (Pak1) binds to, phosphorylates and enhances the enzymatic activity of phosphoglucomutase 1 (PGM), an important regulatory enzyme in cellular glucose utilization and energy homeostasis. Pak1 and PGM were colocalized in model cell systems and showed functional interactions in a physiological setting. Strong direct interaction of PGM with Pak1 but not Pak2, Pak3, or Pak4 was observed. PGM binding was within 75-149 amino acids (aa) of Pak1, while Pak1 binding to PGM was in the N-terminal 96 aa. Pak1-mediated phosphorylation of PGM selectively on threonine 466 significantly increased PGM enzymatic activity and could be blocked by transfection with a dominant-negative Pak1 expression vector and by Pak1-specific small inhibitory RNA. Stable transfection of PGM into PGM-deficient K562 leukemia cells further demonstrated the role of Pak1 in regulating PGM activity. The results presented here provide new evidence that the cell signaling kinase Pak1 is a novel regulator of glucose metabolism through its phosphorylation and regulation of PGM activity. These findings suggest a new mechanism whereby growth factor signaling may coordinately integrate metabolic regulation with established signaling functions of cell cycle regulation and cell growth.
authors.affiliation: Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Anupama
authors.initials: A
authors.lastname: Gururaj
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Barnes
authors.forename: Ratna K
authors.initials: RK
authors.lastname: Vadlamudi
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D004318:Doxycycline / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D010733:Phosphoglucomutase / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D015398:Signal Transduction; D054462:p21-Activated Kinases
chemical_list: D010750:Phosphoproteins; C515903:PAK1 protein, human; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; C488050:PGM1 protein, human; D010733:Phosphoglucomutase; D004318:Doxycycline