TY - JOUR
T1 - Myopalladin promotes muscle growth through modulation of the serum response factor pathway
AU - Filomena, Maria Carmela
AU - Yamamoto, Daniel L.
AU - Caremani, Marco
AU - Kadarla, Vinay K.
AU - Mastrototaro, Giuseppina
AU - Serio, Simone
AU - Vydyanath, Anupama
AU - Mutarelli, Margherita
AU - Garofalo, Arcamaria
AU - Pertici, Irene
AU - Knöll, Ralph
AU - Nigro, Vincenzo
AU - Luther, Pradeep K.
AU - Lieber, Richard L.
AU - Beck, Moriah R.
AU - Linari, Marco
AU - Bang, Marie Louise
N1 - Funding Information:
We thank Dr. Ju Chen (University of California San Diego, CA, USA) for assistance with the generation of MKO mice as well as the initial analyses of the mice. Furthermore, we thank Dr. Derek Frank (Universit?tsklinikum Schleswig-Holstein, Kiel, Germany) for providing adenovirus expressing SMA luciferase, Renilla luciferase, and LacZ; Dr. Athanassia Sotiropoulos (Cochin Institute, Paris, France) for providing adenovirus expressing constitutive active SRF; Dr. Carol Otey (University of North Carolina, Chapel Hill, NC, USA) for providing PALLD antibodies; Dr. Maria K. Vartiainen (University of Helsinki, Helsinki, Finland) and the Protein Production Group at the University of Kansas for providing plasmids; Dr. Annamaria Carissimo (Tigem, Naples, Italy) for statistical analysis of RNA-Seq data; Dr. Simona Lodato for assistance with electroporation in vivo; Dr. Pierluigi Carullo for assistance with mouse procedures; Alessendra Rodan? and Marco Vacchiano for mouse maintenance and genotyping; the Humanitas imaging facility for assistance with microscopy analyses, and Dr. Vincenzo Lombardi for critical reading of the manuscript. This work was supported by the Italian Space Agency (ASI; grant number 2015-009-R.0) to M.L.B.; the Italian Telethon Foundation (grant number GGP12282) to M.L.B., M.L., and V.N.; the Italian Ministry of Education, Universities and Research (MiUR PRIN 2010?2011; grant number 2010R8JK2X_006) to M.L.B. and M.L., the Italian Ministry of Health (grant number RF-MUL-2007-666195) to M.L.B., M.L., and V.N.; the Cariplo Foundation (grant number 2007.5812) to M.L.B.; the National Center for Research Resources (grant number 5P20RR017708) and the National Institute of General Medical Sciences (grant numbers 8P20GM103420 and R15 GM120670) from the National Institutes of Health (NIH) to M.R.B.; British Heart Foundation grant (RG/11/21/29335) to P.K.L.; and NIH grants (AR40050 and P30 AR061303) to R.L.L. The authors of this manuscript certify that they comply with the ethical guidelines for authorship and publishing in the Journal of Cachexia, Sarcopenia and Muscle.
Funding Information:
We thank Dr. Ju Chen (University of California San Diego, CA, USA) for assistance with the generation of MKO mice as well as the initial analyses of the mice. Furthermore, we thank Dr. Derek Frank (Universitätsklinikum Schleswig‐Holstein, Kiel, Germany) for providing adenovirus expressing SMA luciferase, Renilla luciferase, and LacZ; Dr. Athanassia Sotiropoulos (Cochin Institute, Paris, France) for providing adenovirus expressing constitutive active SRF; Dr. Carol Otey (University of North Carolina, Chapel Hill, NC, USA) for providing PALLD antibodies; Dr. Maria K. Vartiainen (University of Helsinki, Helsinki, Finland) and the Protein Production Group at the University of Kansas for providing plasmids; Dr. Annamaria Carissimo (Tigem, Naples, Italy) for statistical analysis of RNA‐Seq data; Dr. Simona Lodato for assistance with electroporation in vivo ; Dr. Pierluigi Carullo for assistance with mouse procedures; Alessendra Rodanò and Marco Vacchiano for mouse maintenance and genotyping; the Humanitas imaging facility for assistance with microscopy analyses, and Dr. Vincenzo Lombardi for critical reading of the manuscript. This work was supported by the Italian Space Agency (ASI; grant number 2015‐009‐R.0) to M.L.B.; the Italian Telethon Foundation (grant number GGP12282) to M.L.B., M.L., and V.N.; the Italian Ministry of Education, Universities and Research (MiUR PRIN 2010–2011; grant number 2010R8JK2X_006) to M.L.B. and M.L., the Italian Ministry of Health (grant number RF‐MUL‐2007‐666195) to M.L.B., M.L., and V.N.; the Cariplo Foundation (grant number 2007.5812) to M.L.B.; the National Center for Research Resources (grant number 5P20RR017708) and the National Institute of General Medical Sciences (grant numbers 8P20GM103420 and R15 GM120670) from the National Institutes of Health (NIH) to M.R.B.; British Heart Foundation grant (RG/11/21/29335) to P.K.L.; and NIH grants (AR40050 and P30 AR061303) to R.L.L. The authors of this manuscript certify that they comply with the ethical guidelines for authorship and publishing in the Journal of Cachexia, Sarcopenia and Muscle .
Publisher Copyright:
© 2019 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of Society on Sarcopenia, Cachexia and Wasting Disorders
PY - 2020/2/1
Y1 - 2020/2/1
N2 - Background: Myopalladin (MYPN) is a striated muscle-specific, immunoglobulin-containing protein located in the Z-line and I-band of the sarcomere as well as the nucleus. Heterozygous MYPN gene mutations are associated with hypertrophic, dilated, and restrictive cardiomyopathy, and homozygous loss-of-function truncating mutations have recently been identified in patients with cap myopathy, nemaline myopathy, and congenital myopathy with hanging big toe. Methods: Constitutive MYPN knockout (MKO) mice were generated, and the role of MYPN in skeletal muscle was studied through molecular, cellular, biochemical, structural, biomechanical, and physiological studies in vivo and in vitro. Results: MKO mice were 13% smaller compared with wild-type controls and exhibited a 48% reduction in myofibre cross-sectional area (CSA) and significantly increased fibre number. Similarly, reduced myotube width was observed in MKO primary myoblast cultures. Biomechanical studies showed reduced isometric force and power output in MKO mice as a result of the reduced CSA, whereas the force developed by each myosin molecular motor was unaffected. While the performance by treadmill running was similar in MKO and wild-type mice, MKO mice showed progressively decreased exercise capability, Z-line damage, and signs of muscle regeneration following consecutive days of downhill running. Additionally, MKO muscle exhibited progressive Z-line widening starting from 8 months of age. RNA-sequencing analysis revealed down-regulation of serum response factor (SRF)-target genes in muscles from postnatal MKO mice, important for muscle growth and differentiation. The SRF pathway is regulated by actin dynamics as binding of globular actin to the SRF-cofactor myocardin-related transcription factor A (MRTF-A) prevents its translocation to the nucleus where it binds and activates SRF. MYPN was found to bind and bundle filamentous actin as well as interact with MRTF-A. In particular, while MYPN reduced actin polymerization, it strongly inhibited actin depolymerization and consequently increased MRTF-A-mediated activation of SRF signalling in myogenic cells. Reduced myotube width in MKO primary myoblast cultures was rescued by transduction with constitutive active SRF, demonstrating that MYPN promotes skeletal muscle growth through activation of the SRF pathway. Conclusions: Myopalladin plays a critical role in the control of skeletal muscle growth through its effect on actin dynamics and consequently the SRF pathway. In addition, MYPN is important for the maintenance of Z-line integrity during exercise and aging. These results suggest that muscle weakness in patients with biallelic MYPN mutations may be associated with reduced myofibre CSA and SRF signalling and that the disease phenotype may be aggravated by exercise.
AB - Background: Myopalladin (MYPN) is a striated muscle-specific, immunoglobulin-containing protein located in the Z-line and I-band of the sarcomere as well as the nucleus. Heterozygous MYPN gene mutations are associated with hypertrophic, dilated, and restrictive cardiomyopathy, and homozygous loss-of-function truncating mutations have recently been identified in patients with cap myopathy, nemaline myopathy, and congenital myopathy with hanging big toe. Methods: Constitutive MYPN knockout (MKO) mice were generated, and the role of MYPN in skeletal muscle was studied through molecular, cellular, biochemical, structural, biomechanical, and physiological studies in vivo and in vitro. Results: MKO mice were 13% smaller compared with wild-type controls and exhibited a 48% reduction in myofibre cross-sectional area (CSA) and significantly increased fibre number. Similarly, reduced myotube width was observed in MKO primary myoblast cultures. Biomechanical studies showed reduced isometric force and power output in MKO mice as a result of the reduced CSA, whereas the force developed by each myosin molecular motor was unaffected. While the performance by treadmill running was similar in MKO and wild-type mice, MKO mice showed progressively decreased exercise capability, Z-line damage, and signs of muscle regeneration following consecutive days of downhill running. Additionally, MKO muscle exhibited progressive Z-line widening starting from 8 months of age. RNA-sequencing analysis revealed down-regulation of serum response factor (SRF)-target genes in muscles from postnatal MKO mice, important for muscle growth and differentiation. The SRF pathway is regulated by actin dynamics as binding of globular actin to the SRF-cofactor myocardin-related transcription factor A (MRTF-A) prevents its translocation to the nucleus where it binds and activates SRF. MYPN was found to bind and bundle filamentous actin as well as interact with MRTF-A. In particular, while MYPN reduced actin polymerization, it strongly inhibited actin depolymerization and consequently increased MRTF-A-mediated activation of SRF signalling in myogenic cells. Reduced myotube width in MKO primary myoblast cultures was rescued by transduction with constitutive active SRF, demonstrating that MYPN promotes skeletal muscle growth through activation of the SRF pathway. Conclusions: Myopalladin plays a critical role in the control of skeletal muscle growth through its effect on actin dynamics and consequently the SRF pathway. In addition, MYPN is important for the maintenance of Z-line integrity during exercise and aging. These results suggest that muscle weakness in patients with biallelic MYPN mutations may be associated with reduced myofibre CSA and SRF signalling and that the disease phenotype may be aggravated by exercise.
KW - Actin dynamics
KW - Knockout mouse
KW - Muscle growth
KW - Sarcomere
KW - Serum response factor pathway
KW - Skeletal muscle
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U2 - 10.1002/jcsm.12486
DO - 10.1002/jcsm.12486
M3 - Article
C2 - 31647200
AN - SCOPUS:85074619110
VL - 11
SP - 169
EP - 194
JO - Journal of Cachexia, Sarcopenia and Muscle
JF - Journal of Cachexia, Sarcopenia and Muscle
SN - 2190-5991
IS - 1
ER -