TY - JOUR
T1 - Hydrophobic imbalance in the cytoplasmic domain of phospholamban is a determinant for lethal dilated cardiomyopathy
AU - Ceholski, Delaine K.
AU - Trieber, Catharine A.
AU - Young, Howard S.
PY - 2012/5/11
Y1 - 2012/5/11
N2 - The sarco(endo)plasmic reticulum calcium ATPase (SERCA) and its regulatory partner phospholamban (PLN) are essential for myocardial contractility. Arg 9 → Cys (R9C) and Arg14 deletion (R14del) mutations in PLN are associated with lethal dilated cardiomyopathy in humans. To better understand these mutations, we made a series of amino acid substitutions in the cytoplasmic domain of PLN and tested their ability to inhibit SERCA. R9C is a complete loss-of-function mutant of PLN, whereas R14del is a mild loss-of-function mutant. When combined with wild-type PLN to simulate heterozygous conditions, the mutants had a dominant negative effect on SERCA function. Aseries of targeted mutations in this region of the PLN cytoplasmic domain (8TRSAIRR14) demonstrated the importance of hydrophobic balance in proper PLN regulation of SERCA. We found that Arg 9 → Leu and Thr8 → Cys substitutions mimicked the behavior of the R9C mutant, and an Arg14 → Ala substitution mimicked the behavior of the R14del mutant. The results reveal that the change in hydrophobicity resulting from the R9C and R14del mutations is sufficient to explain the loss of function and persistent interaction with SERCA. Hydrophobic imbalance in the cytoplasmic domain of PLN appears to be a predictor for the development and progression of dilated cardiomyopathy.
AB - The sarco(endo)plasmic reticulum calcium ATPase (SERCA) and its regulatory partner phospholamban (PLN) are essential for myocardial contractility. Arg 9 → Cys (R9C) and Arg14 deletion (R14del) mutations in PLN are associated with lethal dilated cardiomyopathy in humans. To better understand these mutations, we made a series of amino acid substitutions in the cytoplasmic domain of PLN and tested their ability to inhibit SERCA. R9C is a complete loss-of-function mutant of PLN, whereas R14del is a mild loss-of-function mutant. When combined with wild-type PLN to simulate heterozygous conditions, the mutants had a dominant negative effect on SERCA function. Aseries of targeted mutations in this region of the PLN cytoplasmic domain (8TRSAIRR14) demonstrated the importance of hydrophobic balance in proper PLN regulation of SERCA. We found that Arg 9 → Leu and Thr8 → Cys substitutions mimicked the behavior of the R9C mutant, and an Arg14 → Ala substitution mimicked the behavior of the R14del mutant. The results reveal that the change in hydrophobicity resulting from the R9C and R14del mutations is sufficient to explain the loss of function and persistent interaction with SERCA. Hydrophobic imbalance in the cytoplasmic domain of PLN appears to be a predictor for the development and progression of dilated cardiomyopathy.
UR - http://www.scopus.com/inward/record.url?scp=84860863765&partnerID=8YFLogxK
U2 - 10.1074/jbc.M112.360859
DO - 10.1074/jbc.M112.360859
M3 - Article
C2 - 22427649
AN - SCOPUS:84860863765
SN - 0021-9258
VL - 287
SP - 16521
EP - 16529
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 20
ER -