Suchergebnisse

DREAM, a neuronal calcium sensor protein, has multiple cellular roles including the regulation of Ca2+ and protein homeostasis. We recently showed that reduced DREAM expression or blockade of DREAM activity by repaglinide is neuroprotective in Huntington's disease (HD). Here we used structure-based drug design to guide the identification of IQM-PC330, which was more potent and had longer lasting effects than repaglinide to inhibit DREAM in cellular and in vivo HD models. We disclosed and validated an unexplored ligand binding site, showing Tyr118 and Tyr130 as critical residues for binding and modulation of DREAM activity. IQM-PC330 binding de-repressed c-fos gene expression, silenced the DREAM effect on KV4.3 channel gating and blocked the ATF6/DREAM interaction. Our results validate DREAM as a valuable target and propose more effective molecules for HD treatment. ; PC was the recipient of a postgraduate FPI fellowship from the Spanish Ministry de Economy, Industry and Competitivity (MINECO). P.C. also thanks the Spanish Society of Therapeutic Chemistry (SEQT) for a Jassen-Cilag Award for young researchers (XVIII Edition, 2016). T.G. holds a Ramón y Cajal contract. D.A.P. holds a CSIC contract. This work was funded by the Spanish Ministery of Economy, Industry and Competitivity (AEI-FEDER, EU grants): BFU2015-67284-R (to M.G.R., R.H.), SAF2017-89554-R (to J.R.N.), SAF2016-75021-R (to C.V.) and SAF2015-66275-C2-2-R (to M.M.M.); the Instituto de Salud Carlos III CIBERNED and CIBERCV programs (to J.R.N. and to C.V., respectively) and the Madrid regional government/Neurodegmodels (to J.R.N.); CSIC grant PIE201880E109 (to M.G.R., R.H. and M.M.M.) and PIE201820E104 (to C.V.). ; Peer reviewed

Deregulated protein and Ca2+ homeostasis underlie synaptic dysfunction and neurodegeneration in Huntington disease (HD); however, the factors that disrupt homeostasis are not fully understood. Here, we determined that expression of downstream regulatory element antagonist modulator (DREAM), a multifunctional Ca2+-binding protein, is reduced in murine in vivo and in vitro HD models and in HD patients. DREAM downregulation was observed early after birth and was associated with endogenous neuroprotection. In the R6/2 mouse HD model, induced DREAM haplodeficiency or blockade of DREAM activity by chronic administration of the drug repaglinide delayed onset of motor dysfunction, reduced striatal atrophy, and prolonged life span. DREAM-related neuroprotection was linked to an interaction between DREAM and the unfolded protein response (UPR) sensor activating transcription factor 6 (ATF6). Repaglinide blocked this interaction and enhanced ATF6 processing and nuclear accumulation of transcriptionally active ATF6, improving prosurvival UPR function in striatal neurons. Together, our results identify a role for DREAM silencing in the activation of ATF6 signaling, which promotes early neuroprotection in HD. ; A. De la Cruz holds a RECAVA contract, A. Prieto and P. Cercós hold FPI fellowships, and T. González holds a Ramón y Cajal contract. J. Casado-Vela holds a JAE-DOC (CSIC) from the Spanish Ministerio de Economía y Competitividad (MINECO), cofunded by the European Social Fund. This work was funded by the Instituto de Salud Carlos III/CIBERNED (to J.R. Naranjo, B. Mellström, and A. Rábano), FISS-RIC RD12/0042/0019 (to C. Valenzuela), Madrid regional government/Neurodegmodels (to J.R. Naranjo), MINECO grants SAF2010-21784 and SAF2014-53412-R (to J.R. Naranjo), SAF2012-32209 (to M. Gutierrez-Rodriguez), SAF2010-14916 and SAF2013-45800-R (to C. Valenzuela), and a grant from the Swedish Research Council (J.Y. Li). ; Peer Reviewed