GIV•Kindlin interaction is required for Kindlin-Mediated Integrin Recognition and Activation

Abstract

The eTOC blurb (50 words)Integrins mediate cell adhesion to the extracellular matrix; their dysregulation fuels inflammation, cancer cell invasion and metastasis. Authors show how two pro-metastatic scaffold proteins, Kindlin and GIV/Girdin bind and cooperatively enhance their allosteric coupling to integrins, and their subsequent activation.Findings reveal novel interfaces in integrin signaling for pharmacologic manipulation. HIGHLIGHTS• GIV and Kindlin(K2), two integrin adaptors that promote metastasis, bind each other • Binding of GIV or integrin to K2 allosterically enhances GIV•K2•integrin complexes• Binding is required for the maximal recruitment of GIV and K2 to active integrins • Binding facilitates integrin clustering, activation, tumor cell adhesion, invasion. ABSTRACT (150 words)Cells perceive and respond to the extracellular matrix (ECM) via integrin receptors; their dysregulation has been implicated in inflammation and cancer metastasis. Here we show that a guanine nucleotide exchange modulator of trimeric-GTPase Gαi, GIV (a.k.a Girdin), directly binds the integrin adaptor Kindlin-2. A noncanonical short linear motif within GIV's C-terminus binds Kindlin-2-FERM3 domain at a site that is distinct from the binding site for the canonical NPxY motif on the -integrin tail. Binding of GIV to Kindlin-2 allosterically enhances Kindlin-2's affinity for β 1-integrin. Consequently, integrin activation and clustering are maximized, which augments cell adhesion, spreading and invasion. Findings elucidate how the GIV•Kindlin-2 complex has a two-fold impact: it allosterically synergizes integrin activation and enables β 1-integrins to indirectly access and modulate trimeric GTPases via the complex. Furthermore, Cox proportional-hazard models on tumor transcriptomics provide trans-scale evidence of synergistic interactions between GIV•Kindlin-2•β1-integrin on time to progression to metastasis.

Regulation of DNA damage response by trimeric G-protein Signaling

“…Who binds, and who does not may be dictated by the residues flanking the SLIM, as shown in other instances (64). These findings are in keeping with the fact that GIV-CT is an intrinsically disordered protein (IDP) (41,65) comprised of distinct SLIMs, of which the BRCT-binding motif described here is an example (see Fig S3A ). SLIMs enable GIV to couple G protein signaling to a myriad of molecular sensors, of both the outside of the cell (i.e., receptors; [reviewed in (66)]) or its interior (67).…”

TLR4 signaling and macrophage inflammatory responses are dampened by GIV/Girdin

“…Furthermore, using in vitro pulldown assay between recombinant TLR4-TIR (bait) and Gαi3 (prey) proteins in the presence or absence of GIV-CT, we confirmed that GIV facilitates the formation of a TLR4•GIV•Gαi ternary complexes (Figure 6C). Gαi3 bound TLR4 exclusively in the presence on GIV, suggesting that GIV acts as a physical link between TLR4 and Gαi, as it has been demonstrated to do for multiple RTKs ( 25) and for β1-integrin (35).…”

A Multiomic Analysis Reveals How Breast Cancers Disseminated to the Bone Marrow Acquire Aggressive Phenotypes through Tumor-Stroma Tunnels

“…Although GIV was prioritized through computational rationale (Fig 3E-I (25), survival after DNA damage (26), invasiveness (26), chemoresistance (27) and acquisition of metastatic potential (28)) by diverse groups in a multitude of cancers, including breast (29) and is considered to be a metastasis-related protein (30). Second, unlike stromal cells (31,32) and triple negative breast cancers, which express high levels of GIV, ER+ breast cancer cells, such as MCF7 and T47D, have been shown to be GIVdeficient (33) due to an alternative splicing event [intron 19 retention], which leads to the loss of the resultant transcript to non-sense mediated decay.…”