Constitutively active Galpha16 stimulates STAT3 via a c-Src/JAK- and ERK-dependent mechanism

J Biol Chem. 2003 Dec 26;278(52):52154-65. doi: 10.1074/jbc.M307299200. Epub 2003 Oct 9.

Abstract

The hematopoietic-specific Galpha16 protein has recently been shown to mediate receptor-induced activation of the signal transducer and activator of transcription 3 (STAT3). In the present study, we have delineated the mechanism by which Galpha16 stimulates STAT3 in human embryonic kidney 293 cells. A constitutively active Galpha16 mutant, Galpha16QL, stimulated STAT3-dependent luciferase activity as well as the phosphorylation of STAT3 at both Tyr705 and Ser727. Galpha16QL-induced STAT3 activation was enhanced by overexpression of extracellular signal-regulated kinase 1 (ERK1), but was inhibited by U0126, a Raf-1 inhibitor, and coexpression of the dominant negative mutants of Ras and Rac1. Inhibition of phospholipase Cbeta, protein kinase C, and calmodulin-dependent kinase II by their respective inhibitors also suppressed Galpha16QL-induced STAT3 activation. The involvement of tyrosine kinases such as c-Src and Janus kinase 2 and 3 (JAK2 and JAK3) in Galpha16QL-induced activation of STAT3 was illustrated by the combined use of selective inhibitors and dominant negative mutants. In contrast, c-Jun N-terminal kinase, p38 MAPK, RhoA, Cdc42, phosphatidylinositol 3-kinase, and the epidermal growth factor receptor did not appear to be required. Similar observations were obtained with human erythroleukemia cells, where STAT3 phosphorylation was stimulated by C5a in a PTX-insensitive manner. Collectively, these results highlight the important regulatory roles of the Ras/Raf/MEK/ERK and c-Src/JAK pathways on the stimulation of STAT3 by activated Galpha16. Demonstration of the involvement of different kinases in Galpha16QL-induced STAT3 activation supports the involvement of multiple signaling pathways in the regulation of transcription by G proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Butadienes / pharmacology
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Cell Line
  • Cell Line, Tumor
  • Complement C5a / metabolism
  • DNA, Complementary / metabolism
  • DNA-Binding Proteins / metabolism*
  • Dose-Response Relationship, Drug
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • GTP-Binding Protein alpha Subunits, Gq-G11
  • Genes, Dominant
  • Genes, Reporter
  • Heterotrimeric GTP-Binding Proteins / chemistry*
  • Heterotrimeric GTP-Binding Proteins / metabolism*
  • Humans
  • Isoenzymes / metabolism
  • JNK Mitogen-Activated Protein Kinases
  • Luciferases / metabolism
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases / metabolism*
  • Models, Biological
  • Mutation
  • Nitriles / pharmacology
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phospholipase C beta
  • Phosphorylation
  • Protein Kinase C / metabolism
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins c-raf / metabolism
  • STAT3 Transcription Factor
  • Serine / chemistry
  • Signal Transduction
  • Time Factors
  • Trans-Activators / metabolism*
  • Transfection
  • Type C Phospholipases / metabolism
  • Tyrosine / chemistry
  • cdc42 GTP-Binding Protein / metabolism
  • p38 Mitogen-Activated Protein Kinases
  • rac1 GTP-Binding Protein / metabolism
  • ras Proteins / metabolism
  • rhoA GTP-Binding Protein / metabolism
  • src-Family Kinases / metabolism*

Substances

  • Butadienes
  • DNA, Complementary
  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • Isoenzymes
  • Nitriles
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • Trans-Activators
  • U 0126
  • Tyrosine
  • Serine
  • Complement C5a
  • Luciferases
  • Phosphatidylinositol 3-Kinases
  • Protein-Tyrosine Kinases
  • src-Family Kinases
  • Proto-Oncogene Proteins c-raf
  • Protein Kinase C
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Type C Phospholipases
  • Phospholipase C beta
  • G protein alpha 16
  • GTP-Binding Protein alpha Subunits, Gq-G11
  • Heterotrimeric GTP-Binding Proteins
  • cdc42 GTP-Binding Protein
  • rac1 GTP-Binding Protein
  • ras Proteins
  • rhoA GTP-Binding Protein