Src SH2 arginine 175 is required for cell motility: specific focal adhesion kinase targeting and focal adhesion...

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Src kinase is vital for cell adhesion signaling and motility.
• Src interacts with focal adhesion kinase (FAK) via its SH2 domain, activating it for downstream phosphorylation.
• The SH2 domain's role in targeting Src to focal adhesions (FAs) for substrate phosphorylation was investigated.

Purpose of the Study:

• To determine if the Src SH2 domain's targeting function to FAs is essential for Src-mediated cell motility and malignant transformation.
• To elucidate the specific role of Src-FAK interaction versus SH2 domain-mediated targeting in Src function.

Main Methods:

• Engineered an R175L mutation in cSrc to disrupt FAK pY397 interaction.
• Analyzed substrate phosphorylation, malignant transformation, cell motility, and FA generation in SYF cells expressing wild-type Src and SrcR175L.
• Reconstituted wild-type motile behavior and FA formation by directing SrcR175L to FAs.

Main Results:

• The R175L mutation constitutively opened Src kinase, increasing substrate phosphorylation but not promoting malignant transformation.
• SrcR175L cells exhibited significant motility defects and impaired FA generation.
• Directing SrcR175L to FAs restored wild-type motility and FA formation.

Conclusions:

• The SH2 domain's capacity to recruit Src to FAs is crucial for normal Src function, independent of simple Src-FAK scaffolding.
• Targeting of Src to focal adhesions by the SH2 domain is critical for cell motility and FA formation.
• This study highlights the importance of precise localization for kinase activity in cellular processes.