Phospholemman (PLM), a 72 amino acid single span transmembrane protein, is the major phosphorylation substrate in cardiac membranes in response to adrenergic stimulation. PLM belongs to the newly identified FXYD family of small ion transport regulators. The function of PLM in the heart is unknown except that its mRNA expression is increased after myocardial infarction (Ml). We were the first to show that PLM overexpression affected rat cardiac myocyte contractility and Ca homeostasis; that PLM colocalized with Na/Ca exchanger (NCX1) in cardiac myocytes, that PLM co-immunoprecipitated with NCX1, that PLM overexpression inhibited reverse NCX1 current, and that PLM downregulation enhanced both forward and reverse NCX1 currents. Our HYPOTHESES are: (i) PLM regulates NCX1 and/or Na,K-ATPase (NKA) activities; (ii) phosphorylation is the major mechanism by which PLM regulates NCX1; and (iii) contractile abnormalities post-Mi is partly accounted for by PLM overexpression.
Our SPECIFIC AIMS are: (i) overexpress and downregulate PLM in cardiac myocytes and evaluate the effects on NKA activity; (ii) establish a heterologous expression system to study interaction of PLM (and its mutants) and NCX1, by measuring its effects of NCX1 current and Na-dependent Ca uptake, and its ability to co-immunoprecipitate NCX1; (iii) using the heterologous expression system and mutagenesis, establish the region of PLM that is critical for regulation of NCX1; (iv) evaluate the role of PLM phosphorylation on NCX1 inhibition: serine mutants will be expressed in PLM knockout myocytes; (v) evaulate if PLM protein is overexpressed post-Mi and if contractile abnormalities post-Mi are ameliorated by PLM downregulation. We will use 3 model systems: cultured adult rat cardiac myocytes, HEK293 cells, and PLM knockout mouse.We will employ biophysical, biochemical, and standard molecular biological methods. Our proposed studies will generate knowledge regarding novel pathways involved in physiological modulation of NCX1 and NKA, and the role of PLM in pathophysiological states.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL074854-01A2
Application #
6965457
Study Section
Electrical Signaling, Ion Transport, and Arrhythmias Study Section (ESTA)
Program Officer
Varghese, Jamie
Project Start
2005-07-01
Project End
2009-06-30
Budget Start
2005-07-01
Budget End
2006-06-30
Support Year
1
Fiscal Year
2005
Total Cost
$329,625
Indirect Cost
Name
Pennsylvania State University
Department
Physiology
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Myers, Valerie D; Tomar, Dhanendra; Madesh, Muniswamy et al. (2018) Haplo-insufficiency of Bcl2-associated athanogene 3 in mice results in progressive left ventricular dysfunction, ?-adrenergic insensitivity, and increased apoptosis. J Cell Physiol 233:6319-6326
Cheung, Joseph Y; Miller, Barbara A (2017) Transient Receptor Potential-Melastatin Channel Family Member 2: Friend or Foe. Trans Am Clin Climatol Assoc 128:308-329
Bao, Lei; Chen, Shu-Jen; Conrad, Kathleen et al. (2016) Depletion of the Human Ion Channel TRPM2 in Neuroblastoma Demonstrates Its Key Role in Cell Survival through Modulation of Mitochondrial Reactive Oxygen Species and Bioenergetics. J Biol Chem 291:24449-24464
Judenherc-Haouzi, Annick; Zhang, Xue-Qian; Sonobe, Takashi et al. (2016) Methylene blue counteracts H2S toxicity-induced cardiac depression by restoring L-type Ca channel activity. Am J Physiol Regul Integr Comp Physiol 310:R1030-44
Carr 3rd, Richard; Schilling, Justin; Song, Jianliang et al. (2016) ?-arrestin-biased signaling through the ?2-adrenergic receptor promotes cardiomyocyte contraction. Proc Natl Acad Sci U S A 113:E4107-16
Feldman, Arthur M; Gordon, Jennifer; Wang, JuFang et al. (2016) BAG3 regulates contractility and Ca(2+) homeostasis in adult mouse ventricular myocytes. J Mol Cell Cardiol 92:10-20
Wasilewski, Melissa A; Grisanti, Laurel A; Song, Jianliang et al. (2016) Vasopressin type 1A receptor deletion enhances cardiac contractility, ?-adrenergic receptor sensitivity and acute cardiac injury-induced dysfunction. Clin Sci (Lond) 130:2017-2027
Zhang, Xue-Qian; Wang, JuFang; Song, Jianliang et al. (2015) Regulation of L-type calcium channel by phospholemman in cardiac myocytes. J Mol Cell Cardiol 84:104-11
Hoffman, Nicholas E; Miller, Barbara A; Wang, JuFang et al. (2015) Ca²? entry via Trpm2 is essential for cardiac myocyte bioenergetics maintenance. Am J Physiol Heart Circ Physiol 308:H637-50
Cheung, Joseph Y; Gordon, Jennifer; Wang, JuFang et al. (2015) Cardiac Dysfunction in HIV-1 Transgenic Mouse: Role of Stress and BAG3. Clin Transl Sci 8:305-10

Showing the most recent 10 out of 48 publications