Amyloidogenic light chains induce cardiomyocyte contractile dysfunction and apoptosis via a non-canonical p38alpha MAPK pathway.
Patients with primary (AL) cardiac amyloidosis suffer from progressive cardiomyopathy with a median survival of less than 8 months and a 5-year survival of <10%. Contributing to this poor prognosis is the fact that these patients generally do not tolerate standard heart failure therapies. The molecular mechanisms underlying this deadly form of heart disease remain unclear. Although interstitial amyloid fibril deposition of Ig light chain proteins is a major cause of cardiac dysfunction in AL cardiac amyloidosis, we have previously shown that amyloid precursor proteins directly impair cardiac function at the cellular and isolated organ levels, independent of fibril formation. In this study, we report that amyloidogenic light chain (AL-LC) proteins provoke oxidative stress, cellular dysfunction, and apoptosis in isolated adult cardiomyocytes through activation of p38 mitogen-activated protein kinase (MAPK). AL-LC-induced p38 activation was found to be independent of the upstream MAPK kinase, MKK3/6, and instead depends upon transforming growth factor-beta-activated protein kinase-1 binding protein-1 (TAB1)-mediated p38alpha MAPK autophosphorylation. Treatment of cardiomyocytes with SB203580, a selective p38 MAPK inhibitor, significantly attenuated AL-LC-induced oxidative stress, cellular dysfunction, and apoptosis. Our data provide a unique mechanistic insight into the pathogenesis of AL-LC cardiac toxicity and suggest that TAB1-mediated p38alpha MAPK autophosphorylation may serve as an important event leading to cardiac dysfunction and subsequent heart failure.
Cardiac Muscle Research Laboratory, Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Jianru
J
Shi
Jian
J
Guan
Bingbing
B
Jiang
Daniel A
DA
Brenner
Federica
F
Del Monte
Jennifer E
JE
Ward
Lawreen H
LH
Connors
Douglas B
DB
Sawyer
Marc J
MJ
Semigran
Thomas E
TE
Macgillivray
David C
DC
Seldin
Rodney
R
Falk
Ronglih
R
Liao
D000682:Amyloid / Q000502:physiology*; D017209:Apoptosis; D004789:Enzyme Activation; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000682:Amyloid; D007093:Imidazoles; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580