TY - JOUR

T1 - Isoform-specific Na,K-ATPase and membrane cholesterol remodeling in motor endplates in distinct mouse models of myodystrophy

AU - Kravtsova, Violetta V

AU - Bouzinova, Elena V

AU - Chibalin, Alexander V

AU - Matchkov, Vladimir V

AU - Krivoi, Igor I

PY - 2020/5

Y1 - 2020/5

N2 - Na,K-ATPase is a membrane transporter critically important for skeletal muscle function. Mdx and Bla/J mice are the experimental models of Duchenne muscular dystrophy and dysferlinopathy. The molecular mechanism behind myodystrophy is of therapeutic importance; however, the detailed role of Na,K-ATPase in these dysfunctions has not previously been addressed. This study examines the function of the α1 and α2 Na,K-ATPase isozymes in diaphragm and soleus muscles from mdx and Bla/J mice compared to control С57Bl/6 mice. Conventional electrophysiology, quantitative PCR and Western blotting, co-immunoprecipitation as well as confocal microscopy with cytochemistry were used. In diaphragm muscle fibers from mdx and Bla/J mice plasma membrane was depolarized due to specific loss of the α2 Na,K-ATPase electrogenic activity, which was more pronounced in the junctional (motor endplate) region; the a2 Na,K-ATPase abundance decrease and membrane cholesterol re-distribution were observed throughout the sarcolemma. However, the α2 Na,K-ATPase protein content as well as mRNA expression were specifically and significantly reduced only in mdx mice. FXYD1 (an auxiliary subunit, which modulates Na,K-ATPase activity) abundance and its association with the α2 Na,K-ATPase were decreased in both mouse models of myodystrophy, presumably as response to impaired functioning of the enzyme. Soleus muscles from mdx and Bla/J mice demonstrated difference in the pattern of the α2 Na,K-ATPase and cholesterol abnormalities compared to diaphragm muscles. Our findings indicate that these distinct mouse models of myodystrophy are characterized by α2 Na,K-ATPase and membrane cholesterol impairments, which can be a result of adaptive skeletal muscle remodeling under chronic motor dysfunction.

AB - Na,K-ATPase is a membrane transporter critically important for skeletal muscle function. Mdx and Bla/J mice are the experimental models of Duchenne muscular dystrophy and dysferlinopathy. The molecular mechanism behind myodystrophy is of therapeutic importance; however, the detailed role of Na,K-ATPase in these dysfunctions has not previously been addressed. This study examines the function of the α1 and α2 Na,K-ATPase isozymes in diaphragm and soleus muscles from mdx and Bla/J mice compared to control С57Bl/6 mice. Conventional electrophysiology, quantitative PCR and Western blotting, co-immunoprecipitation as well as confocal microscopy with cytochemistry were used. In diaphragm muscle fibers from mdx and Bla/J mice plasma membrane was depolarized due to specific loss of the α2 Na,K-ATPase electrogenic activity, which was more pronounced in the junctional (motor endplate) region; the a2 Na,K-ATPase abundance decrease and membrane cholesterol re-distribution were observed throughout the sarcolemma. However, the α2 Na,K-ATPase protein content as well as mRNA expression were specifically and significantly reduced only in mdx mice. FXYD1 (an auxiliary subunit, which modulates Na,K-ATPase activity) abundance and its association with the α2 Na,K-ATPase were decreased in both mouse models of myodystrophy, presumably as response to impaired functioning of the enzyme. Soleus muscles from mdx and Bla/J mice demonstrated difference in the pattern of the α2 Na,K-ATPase and cholesterol abnormalities compared to diaphragm muscles. Our findings indicate that these distinct mouse models of myodystrophy are characterized by α2 Na,K-ATPase and membrane cholesterol impairments, which can be a result of adaptive skeletal muscle remodeling under chronic motor dysfunction.

KW - Duchenne muscular dystrophy

KW - Na,K-ATPase isoforms

KW - dysferlinopathy

KW - membrane cholesterol

KW - motor endplate

U2 - 10.1152/ajpcell.00453.2019

DO - 10.1152/ajpcell.00453.2019

M3 - Journal article

C2 - 32293933

VL - 318

SP - C1030-C1041

JO - American Journal of Physiology: Cell Physiology

JF - American Journal of Physiology: Cell Physiology

SN - 0363-6143

IS - 5

ER -