Transgenic overexpression of human DMPK accumulates into hypertrophic cardiomyopathy, myotonic myopathy and hypotension traits of myotonic dystrophy.
Abnormal expression of human myotonic dystrophy protein kinase (hDMPK) gene products has been implicated in myotonic dystrophy type 1 (DM1), yet the impact of distress accumulation produced by persistent overexpression of this poorly understood member of the Rho kinase-related protein kinase gene-family remains unknown. Here, in the aged transgenic murine line carrying approximately 25 extra copies of a complete hDMPK gene with all exons and an intact promoter region (Tg26-hDMPK), overexpression of mRNA and protein transgene products in cardiac, skeletal and smooth muscles resulted in deficient exercise endurance, an integrative index of muscle systems underperformance. In contrast to age-matched (11-15 months) wild-type controls, hearts from Tg26-hDMPK developed cardiomyopathic remodeling with myocardial hypertrophy, myocyte disarray and interstitial fibrosis. Hypertrophic cardiomyopathy was associated with a propensity for dysrhythmia and characterized by overt intracellular calcium overload promoting nuclear translocation of transcription factors responsible for maladaptive gene reprogramming. Skeletal muscles in distal limbs of Tg26-hDMPK showed myopathy with myotonic discharges coupled with deficit in sarcolemmal chloride channels, required regulators of hyperexcitability. Fiber degeneration in Tg26-hDMPK resulted in sarcomeric disorganization, centralization of nuclei and tubular aggregation. Moreover, the reduced blood pressure in Tg26-hDMPK indicated deficient arterial smooth muscle tone. Thus, the cumulative stress induced by permanent overexpression of hDMPK gene products translates into an increased risk for workload intolerance, hypertrophic cardiomyopathy with dysrhythmia, myotonic myopathy and hypotension, all distinctive muscle traits of DM1. Proper expression of hDMPK is, therefore, mandatory in supporting the integral balance among cytoarchitectural infrastructure, ion-homeostasis and viability control in various muscle cell types.
Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
D Fearghas
DF
O'Cochlain
Carmen
C
Perez-Terzic
Santiago
S
Reyes
Garvan C
GC
Kane
Atta
A
Behfar
Denice M
DM
Hodgson
Jeffrey A
JA
Strommen
Xiao-Ke
XK
Liu
Walther
W
van den Broek
Derick G
DG
Wansink
Bé
B
Wieringa
Andre
A
Terzic
D000375:Aging / Q000378:metabolism; D000818:Animals; D002312:Cardiomyopathy, Hypertrophic / Q000209:etiology*; D004452:Echocardiography; D005080:Exercise Test; D018628:Gene Dosage; D015870:Gene Expression; D006801:Humans; D007022:Hypotension / Q000209:etiology*; D051379:Mice; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000473:pathology / Q000648:ultrastructure; D009131:Muscle, Smooth, Vascular / Q000473:pathology; D009206:Myocardium / Q000473:pathology / Q000648:ultrastructure; D009223:Myotonic Dystrophy / Q000209:etiology*; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D019076:Transgenes
C585517:DMPK protein, human; C585516:DMPK protein, mouse; D065636:Myotonin-Protein Kinase; D017346:Protein Serine-Threonine Kinases