TY - JOUR

T1 - Nemaline Myopathy-Related Skeletal Muscle α-Actin (ACTA1) Mutation, Asp286Gly, Prevents Proper Strong Myosin Binding and Triggers Muscle Weakness

AU - Ochala, Julien

AU - Ravenscroft, Gianina

AU - Laing, Nigel G.

AU - Nowak, Kristen J.

PY - 2012/9/20

Y1 - 2012/9/20

N2 - Many mutations in the skeletal muscle α-actin gene (ACTA1) lead to muscle weakness and nemaline myopathy. Despite increasing clinical and scientific interest, the molecular and cellular pathogenesis of weakness remains unclear. Therefore, in the present study, we aimed at unraveling these mechanisms using muscles from a transgenic mouse model of nemaline myopathy expressing the ACTA1 Asp286Gly mutation. We recorded and analyzed the mechanics of membrane-permeabilized single muscle fibers. We also performed molecular energy state computations in the presence or absence of Asp286Gly. Results demonstrated that during contraction, the Asp286Gly acts as a "poison-protein" and according to the computational analysis it modifies the actin-actin interface. This phenomenon is likely to prevent proper myosin cross-bridge binding, limiting the fraction of actomyosin interactions in the strong binding state. At the cell level, this decreases the force-generating capacity, and, overall, induces muscle weakness. To counterbalance such negative events, future potential therapeutic strategies may focus on the inappropriate actin-actin interface or myosin binding.

AB - Many mutations in the skeletal muscle α-actin gene (ACTA1) lead to muscle weakness and nemaline myopathy. Despite increasing clinical and scientific interest, the molecular and cellular pathogenesis of weakness remains unclear. Therefore, in the present study, we aimed at unraveling these mechanisms using muscles from a transgenic mouse model of nemaline myopathy expressing the ACTA1 Asp286Gly mutation. We recorded and analyzed the mechanics of membrane-permeabilized single muscle fibers. We also performed molecular energy state computations in the presence or absence of Asp286Gly. Results demonstrated that during contraction, the Asp286Gly acts as a "poison-protein" and according to the computational analysis it modifies the actin-actin interface. This phenomenon is likely to prevent proper myosin cross-bridge binding, limiting the fraction of actomyosin interactions in the strong binding state. At the cell level, this decreases the force-generating capacity, and, overall, induces muscle weakness. To counterbalance such negative events, future potential therapeutic strategies may focus on the inappropriate actin-actin interface or myosin binding.

UR - http://www.scopus.com/inward/record.url?scp=84866645945&partnerID=8YFLogxK

U2 - 10.1371/journal.pone.0045923

DO - 10.1371/journal.pone.0045923

M3 - Journal article

C2 - 23029319

AN - SCOPUS:84866645945

VL - 7

JO - PLoS ONE

JF - PLoS ONE

SN - 1932-6203

IS - 9

M1 - e45923

ER -