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PMID:17599059

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Citation

Kawasaki, Y, Sagara, M, Shibata, Y, Shirouzu, M, Yokoyama, S and Akiyama, T (2007) Identification and characterization of Asef2, a guanine-nucleotide exchange factor specific for Rac1 and Cdc42. Oncogene 26:7620-267

Abstract

The tumor suppressor adenomatous polyposis coli (APC) is mutated in sporadic and familial colorectal tumors. APC interacts with the Rac1-specific guanine-nucleotide exchange factor (GEF) Asef, which contains an APC-binding region (ABR) in addition to Dbl homology (DH), Pleckstrin (PH) and Src homology 3 (SH3) domains. APC stimulates the GEF activity of Asef, and thereby regulates cell adhesion and migration. Here, we have identified a second Asef, termed Asef2, that shows significant structural and functional similarities to Asef. We found that both the N-terminal ABR and SH3 domains of Asef2 are responsible for its interaction with APC. When expressed in HeLa cells, a mutant Asef2 lacking the ABR and SH3 domains, Asef2-DeltaABR/SH3, induced increases in the levels of the active forms of Rac1 and Cdc42. Full-length Asef2 also showed this activity when co-transfected with truncated mutant APC expressed in colorectal tumor cells. Consistent with this, either Asef2-DeltaABR/SH3 or Asef2 plus truncated mutant APC stimulated lamellipodia formation in MDCK cells and filopodia formation in HeLa cells. Furthermore, RNA interference experiments showed that Asef2 is required for migration of colorectal tumor cells expressing truncated APC. These results suggest that similar to Asef, Asef2 plays an important role in cell migration, and that Asef2 activated by truncated mutant APC is required for aberrant migration of colorectal tumor cells.

Links

PubMed Online version:10.1038/sj.onc.1210574

Keywords

Adenomatous Polyposis Coli Protein/genetics; Adenomatous Polyposis Coli Protein/metabolism; Amino Acid Sequence; Animals; Cell Movement/genetics; Cercopithecus aethiops; Colorectal Neoplasms/metabolism; Colorectal Neoplasms/pathology; Dogs; Guanine Nucleotide Exchange Factors/analysis; Guanine Nucleotide Exchange Factors/chemistry; Guanine Nucleotide Exchange Factors/genetics; Guanine Nucleotide Exchange Factors/metabolism; Humans; Molecular Sequence Data; Mutation; Protein Interaction Mapping; Pseudopodia/physiology; cdc42 GTP-Binding Protein/metabolism; rac1 GTP-Binding Protein/metabolism; src Homology Domains/genetics

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

HUMAN:APC

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:Q96N96

F

Seeded From UniProt

complete

HUMAN:APC

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:Q96N96-2

F

Seeded From UniProt

complete

HUMAN:SPT13

part_of

GO:0030027: lamellipodium

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

HUMAN:SPT13

involved_in

GO:0030334: regulation of cell migration

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:SPT13

involved_in

GO:0046847: filopodium assembly

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:SPT13

enables

GO:0005085: guanyl-nucleotide exchange factor activity

ECO:0000315: mutant phenotype evidence used in manual assertion

F

Seeded From UniProt

complete

HUMAN:SPT13

part_of

GO:0030175: filopodium

ECO:0000314: direct assay evidence used in manual assertion

C

Seeded From UniProt

complete

HUMAN:SPT13

involved_in

GO:0030032: lamellipodium assembly

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:SPT13

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:P25054

F

Seeded From UniProt

complete

HUMAN:APC

enables

GO:0005515: protein binding

ECO:0000353: physical interaction evidence used in manual assertion

UniProtKB:P25054

F

Seeded From UniProt

complete

HUMAN:ARHG4

involved_in

GO:0046847: filopodium assembly

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

HUMAN:ARHG4

enables

GO:0005085: guanyl-nucleotide exchange factor activity

ECO:0000315: mutant phenotype evidence used in manual assertion

F

Seeded From UniProt

complete

HUMAN:ARHG4

involved_in

GO:0030032: lamellipodium assembly

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete


See also

References

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