Muscleblind-Like 1 and Muscleblind-Like 3 Depletion Synergistically Enhances Myotonia by Altering Clc-1 RNA Translation.

Autor:	Choi J; Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA., Personius KE; Department of Rehabilitation Science and Program in Neuroscience, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY 14214, USA., DiFranco M; Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA., Dansithong W; Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA., Yu C; Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA., Srivastava S; Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA., Dixon DM; Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA., Bhatt DB; Department of Rehabilitation Science and Program in Neuroscience, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY 14214, USA., Comai L; Department of Microbiology and Immunology, University of Southern California, Los Angeles, CA 90033, USA., Vergara JL; Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA., Reddy S; Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90033, USA.
Jazyk:	angličtina
Zdroj:	EBioMedicine [EBioMedicine] 2015 Jul 31; Vol. 2 (9), pp. 1034-47. Date of Electronic Publication: 2015 Jul 31 (Print Publication: 2015).
DOI:	10.1016/j.ebiom.2015.07.028
Abstrakt:	Loss of Muscleblind-like 1 (Mbnl1) is known to alter Clc-1 splicing to result in myotonia. Mbnl1(ΔE3/ΔE3)/Mbnl3(ΔE2) mice, depleted of Mbnl1 and Mbnl3, demonstrate a profound enhancement of myotonia and an increase in the number of muscle fibers with very low Clc-1 currents, where gClmax values approach ~ 1 mS/cm(2), with the absence of a further enhancement in Clc-1 splice errors, alterations in polyA site selection or Clc-1 localization. Significantly, Mbnl1(ΔE3/ΔE3)/Mbnl3(ΔE2) muscles demonstrate an aberrant accumulation of Clc-1 RNA on monosomes and on the first polysomes. Mbnl1 and Mbnl3 bind Clc-1 RNA and both proteins bind Hsp70 and eEF1A, with these associations being reduced in the presence of RNA. Thus binding of Mbnl1 and Mbnl3 to Clc-1 mRNA engaged with ribosomes can facilitate an increase in the local concentration of Hsp70 and eEF1A to assist Clc-1 translation. Dual depletion of Mbnl1 and Mbnl3 therefore initiates both Clc-1 splice errors and translation defects to synergistically enhance myotonia. As the HSA(LR) model for myotonic dystrophy (DM1) shows similar Clc-1 defects, this study demonstrates that both splice errors and translation defects are required for DM1 pathology to manifest. Research in Context: Research in context: Myotonic Dystrophy type 1 (DM1) is a dominant disorder resulting from the expression of expanded CUG repeat RNA, which aberrantly sequesters and inactivates the muscleblind-like (MBNL) family of proteins. In mice, inactivation of Mbnl1 is known to alter Clc-1 splicing to result in myotonia. We demonstrate that concurrent depletion of Mbnl1 and Mbnl3 results in a synergistic enhancement of myotonia, with an increase in muscle fibers showing low chloride currents. The observed synergism results from the aberrant accumulation of Clc-1 mRNA on monosomes and the first polysomes. This translation error reflects the ability of Mbnl1 and Mbnl3 to act as adaptors that recruit Hsp70 and eEF1A to the Clc-1 mRNA engaged with ribosomes, to facilitate translation. Thus our study demonstrates that Clc-1 RNA translation defects work coordinately with Clc-1 splice errors to synergistically enhance myotonia in mice lacking Mbnl1 and Mbnl3.
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu