EPS8

This gene encodes a member of the EPS8 family. This protein contains one PH domain and one SH3 domain. It functions as part of the EGFR pathway, though its exact role has not been determined. Highly similar proteins in other organisms are involved in the transduction of signals from Ras to Rac and growth factor-mediated actin remodeling. Alternate transcriptional splice variants of this gene have been observed but have not been thoroughly characterized. [provided by RefSeq, Jul 2008]

Full Name

Epidermal Growth Factor Receptor Pathway Substrate 8

Research Area

Signaling adapter that controls various cellular protrusions by regulating actin cytoskeleton dynamics and architecture. Depending on its association with other signal transducers, can regulate different processes. Together with SOS1 and ABI1, forms a trimeric complex that participates in transduction of signals from Ras to Rac by activating the Rac-specific guanine nucleotide exchange factor (GEF) activity. Acts as a direct regulator of actin dynamics by binding actin filaments and has both barbed-end actin filament capping and actin bundling activities depending on the context. Displays barbed-end actin capping activity when associated with ABI1, thereby regulating actin-based motility process: capping activity is auto-inhibited and inhibition is relieved upon ABI1 interaction. Also shows actin bundling activity when associated with BAIAP2, enhancing BAIAP2-dependent membrane extensions and promoting filopodial protrusions. Involved in the regulation of processes such as axonal filopodia growth, stereocilia length, dendritic cell migration and cancer cell migration and invasion. Acts as a regulator of axonal filopodia formation in neurons: in the absence of neurotrophic factors, negatively regulates axonal filopodia formation via actin-capping activity. In contrast, it is phosphorylated in the presence of BDNF leading to inhibition of its actin-capping activity and stimulation of filopodia formation. Component of a complex with WHRN and MYO15A that localizes at stereocilia tips and is required for elongation of the stereocilia actin core. Indirectly involved in cell cycle progression; its degradation following ubiquitination being required during G2 phase to promote cell shape changes.

Biological Process

Actin crosslink formation Source: UniProtKB
Actin cytoskeleton reorganization Source: Ensembl
Actin filament bundle assembly Source: UniProtKB
Actin polymerization-dependent cell motility Source: UniProtKB
Adult locomotory behavior Source: Ensembl
Barbed-end actin filament capping Source: UniProtKB
Behavioral response to ethanol Source: Ensembl
Cellular response to leukemia inhibitory factor Source: Ensembl
Dendritic cell migration Source: UniProtKB
Exit from mitosis Source: UniProtKB
Positive regulation of ruffle assembly Source: GO_Central
Rac protein signal transduction Source: UniProtKB
Regulation of actin filament length Source: UniProtKB
Regulation of cell shape Source: UniProtKB
Regulation of postsynaptic membrane neurotransmitter receptor levels Source: Ensembl
Regulation of Rho protein signal transduction Source: GO_Central
Rho protein signal transduction Source: GO_Central

Cellular Location

Ruffle membrane; Cell cortex; Growth cone; Stereocilium; Synaptosome. Localizes at the tips of the stereocilia of the inner and outer hair cells (By similarity). Localizes to the midzone of dividing cells.

Involvement in disease

Deafness, autosomal recessive, 102 (DFNB102):
A form of non-syndromic deafness characterized by profound hearing loss affecting all frequencies. Vestibular function is unaffected.
Defects in EPS8 are associated with some cancers, such as pancreatic, oral squamous cell carcinomas or pituitary cancers. Contributes to cell transformation in response to growth factor treatment and is overexpressed in a number of tumors, indicating that EPS8 levels must be tightly regulated.

PTM

Ubiquitinated by the SCF(FBXW5) E3 ubiquitin-protein ligase complex during G2 phase, leading to its transient degradation and subsequent cell shape changes required to allow mitotic progression. Reappears at the midzone of dividing cells (By similarity).
Phosphorylation at Ser-625 and Thr-629 by MAPK following BDNF treatment promotes removal from actin and filopodia formation (By similarity). Phosphorylated by several receptor tyrosine kinases.By similarity