Abstract
Adaptor proteins are important mediators in signal transduction. In the present study, we report the cloning and characterization of a novel adaptor protein, XB130. This gene is located on human chromosome 10q25.3 and encodes a protein of 818 amino acids. It contains several Src homology (SH)2- and SH3-binding motifs, two pleckstrin homology domains, a coiled-coil region, and a number of potential tyrosine or serine/threonine phosphorylation sites. Endogenous XB130 interacts with c-Src tyrosine kinase. Their co-expression in COS-7 cells resulted in activation of c-Src and elevated tyrosine phosphorylation of multiple proteins, including XB130 itself. XB130 expression in HEK293 cells enhanced serum response element- and AP-1-dependent transcriptional activation mediated by c-Src. XB130DeltaN, an N-terminal deletion mutant lacking a putative SH3-binding motif and several putative SH2-binding sites, reduced its ability to mediate Src signal transduction. Down-regulation of endogenous XB130 with siRNA reduced c-Src activity, IL-8 production, EGF-induced phosphorylation of Akt and GSK3beta, and altered cell cycles in human lung epithelial cells. These data suggest that XB130 as an adaptor may play an important role in the regulation of signal transduction and cellular functions.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Adaptor Proteins, Signal Transducing / antagonists & inhibitors
-
Adaptor Proteins, Signal Transducing / genetics
-
Adaptor Proteins, Signal Transducing / metabolism*
-
Animals
-
COS Cells
-
CSK Tyrosine-Protein Kinase
-
Chlorocebus aethiops
-
Chromosomes, Human, Pair 10* / genetics
-
Epidermal Growth Factor / pharmacology
-
Epithelial Cells / cytology
-
Epithelial Cells / metabolism*
-
Humans
-
Interleukin-8 / biosynthesis
-
Lung / cytology
-
Lung / metabolism*
-
Phosphorylation / drug effects
-
Protein Binding / drug effects
-
Protein Binding / physiology
-
Protein Processing, Post-Translational / physiology
-
Protein-Tyrosine Kinases / physiology
-
Proto-Oncogene Proteins / physiology
-
Proto-Oncogene Proteins c-akt / metabolism
-
RNA, Small Interfering / genetics
-
RNA, Small Interfering / pharmacology
-
Repressor Proteins / metabolism
-
Serum Response Element / physiology
-
Signal Transduction / drug effects
-
Signal Transduction / physiology*
-
Transcription Factor AP-1 / genetics
-
Transcription Factor AP-1 / metabolism
-
Transcriptional Activation / drug effects
-
Transcriptional Activation / physiology*
-
src Homology Domains / genetics
-
src-Family Kinases
Substances
-
AFAP1L2 protein, human
-
Adaptor Proteins, Signal Transducing
-
CXCL8 protein, human
-
GSKIP protein, human
-
Interleukin-8
-
Proto-Oncogene Proteins
-
RNA, Small Interfering
-
Repressor Proteins
-
Transcription Factor AP-1
-
Epidermal Growth Factor
-
Protein-Tyrosine Kinases
-
CSK Tyrosine-Protein Kinase
-
src-Family Kinases
-
CSK protein, human
-
Proto-Oncogene Proteins c-akt