title: MAP4K4 Is a Threonine Kinase That Phosphorylates FARP1.
abstract: Mitogen-activated protein kinase 4 (MAP4K4) regulates the MEK kinase cascade and is implicated in cytoskeletal rearrangement and migration; however, identifying MAP4K4 substrates has remained a challenge. To ascertain MAP4K4-dependent phosphorylation events, we combined phosphoproteomic studies of MAP4K4 inhibition with in vitro assessment of its kinase specificity. We identified 235 phosphosites affected by MAP4K4 inhibition in cells and found that pTP and pSP motifs were predominant among them. In contrast, in vitro assessment of kinase specificity showed that MAP4K4 favors a pTL motif. We showed that MAP4K4 directly phosphorylates and coimmunoprecipitates with FERM, RhoGEF, and pleckstrin domain-containing protein 1 (FARP1). MAP4K4 inhibition in SH-SY5Y cells increases neurite outgrowth, a process known to involve FARP1. As FARP1 and MAP4K4 both contribute to cytoskeletal rearrangement, the results suggest that MAP4K4 exerts some of its effects on the cytoskeleton via phosphorylation of FARP1.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Schwaid
authors.forename: Chunyan
authors.initials: C
authors.lastname: Su
authors.forename: Paula
authors.initials: P
authors.lastname: Loos
authors.affiliation: Structural Biology and Biophysics, Center for Chemistry Innovation and Excellence, Pfizer Pharmatherapeutics Research and Development , Groton, Connecticut 06340, United States.
authors.forename: Jiang
authors.initials: J
authors.lastname: Wu
authors.affiliation: Structural Biology and Biophysics, Center for Chemistry Innovation and Excellence, Pfizer Pharmatherapeutics Research and Development , Groton, Connecticut 06340, United States.
authors.forename: Chuong
authors.initials: C
authors.lastname: Nguyen
authors.affiliation: W.M. Keck Foundation Biotechnology Resource Laboratory, Yale University , New Haven, Connecticut 06520, United States.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Stone
authors.affiliation: W.M. Keck Foundation Biotechnology Resource Laboratory, Yale University , New Haven, Connecticut 06520, United States.
authors.forename: Jean
authors.initials: J
authors.lastname: Kanyo
authors.affiliation: Structural Biology and Biophysics, Center for Chemistry Innovation and Excellence, Pfizer Pharmatherapeutics Research and Development , Groton, Connecticut 06340, United States.
authors.forename: Kieran F
authors.initials: KF
authors.lastname: Geoghegan
authors.forename: Samit K
authors.initials: SK
authors.lastname: Bhattacharya
authors.forename: Robert L
authors.initials: RL
authors.lastname: Dow
authors.forename: Leonard
authors.initials: L
authors.lastname: Buckbinder
authors.forename: Philip A
authors.initials: PA
authors.lastname: Carpino
mesh_terms: D001681:Biological Assay; D056945:Hep G2 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D015394:Molecular Structure; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D040901:Proteomics; D064067:Rho Guanine Nucleotide Exchange Factors / Q000378:metabolism*
chemical_list: C577227:FARP1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; C117090:MAP4K4 protein, human; D017346:Protein Serine-Threonine Kinases