Phosphatidylinositol-4,5-Biphosphate-Dependent Rearrangement of TRPV4 Cytosolic Tails Enables Channel Activation by Physiological Stimuli

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Phosphatidylinositol-4,5-Biphosphate-Dependent Rearrangement of TRPV4 Cytosolic Tails Enables Channel Activation by Physiological Stimuli

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Title: Phosphatidylinositol-4,5-Biphosphate-Dependent Rearrangement of TRPV4 Cytosolic Tails Enables Channel Activation by Physiological Stimuli
Author: Garcia-Elias, Anna; Mrkonjic, Sanela; Pardo-Pastor, Carlos; Inada, Hitoshi; Hellmich, Ute; Rubio-Moscardó, Fanny; Plata, Cristina; Gaudet, Rachelle; Vicente, Rubén; Valverde, Miguel A.

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Citation: Garcia-Elias, Anna, Sanela Mrkonjic, Carlos Pardo-Pastor, Hitoshi Inada, Ute A. Hellmich, Fanny Rubio-Moscardó, Cristina Plata, Rachelle Gaudet, Rubén Vicente, and Miguel A. Valverde. 2013. Phosphatidylinositol-4,5-Biphosphate-Dependent Rearrangement of TRPV4 Cytosolic Tails Enables Channel Activation by Physiological Stimuli. Proceedings of the National Academy of Sciences 110, no. 23: 9553–9558.
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Abstract: Most transient receptor potential (TRP) channels are regulated by phosphatidylinositol-4,5-biphosphate (PIP\(_2\)), although the structural rearrangements occurring on PIP\(_2\) binding are currently far from clear. Here we report that activation of the TRP vanilloid 4 (TRPV4) channel by hypotonic and heat stimuli requires PIP\(_2\) binding to and rearrangement of the cytosolic tails. Neutralization of the positive charges within the sequence \(^{121}\)KRWRK\(^{125}\), which resembles a phosphoinositide-binding site, rendered the channel unresponsive to hypotonicity and heat but responsive to 4α-phorbol 12,13-didecanoate, an agonist that binds directly to transmembrane domains. Similar channel response was obtained by depletion of PIP\(_2\) from the plasma membrane with translocatable phosphatases in heterologous expression systems or by activation of phospholipase C in native ciliated epithelial cells. PIP\(_2\) facilitated TRPV4 activation by the osmotransducing cytosolic messenger 5′-6’-epoxyeicosatrienoic acid and allowed channel activation by heat in inside-out patches. Protease protection assays demonstrated a PIP\(_2\)-binding site within the N-tail. The proximity of TRPV4 tails, analyzed by fluorescence resonance energy transfer, increased by depleting PIP\(_2\) mutations in the phosphoinositide site or by coexpression with protein kinase C and casein kinase substrate in neurons 3 (PACSIN3), a regulatory molecule that binds TRPV4 N-tails and abrogates activation by cell swelling and heat. PACSIN3 lacking the Bin-Amphiphysin-Rvs (F-BAR) domain interacted with TRPV4 without affecting channel activation or tail rearrangement. Thus, mutations weakening the TRPV4–PIP\(_2\) interacting site and conditions that deplete PIP\(_2\) or restrict access of TRPV4 to PIP\(_2\)—in the case of PACSIN3—change tail conformation and negatively affect channel activation by hypotonicity and heat.
Published Version: doi:10.1073/pnas.1220231110
Other Sources: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3677448/pdf/pnas.201220231.pdf
Terms of Use: This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAA
Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:12563734
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