title: Constitutive overexpression of phosphomimetic phospholemman S68E mutant results in arrhythmias, early mortality, and heart failure: potential involvement of Na+/Ca2+ exchanger.
abstract: Expression and activity of cardiac Na(+)/Ca(2+) exchanger (NCX1) are altered in many disease states. We engineered mice in which the phosphomimetic phospholemman S68E mutant (inhibits NCX1 but not Na(+)-K(+)-ATPase) was constitutively overexpressed in a cardiac-specific manner (conS68E). At 4-6 wk, conS68E mice exhibited severe bradycardia, ventricular arrhythmias, increased left ventricular (LV) mass, decreased cardiac output (CO), and ∼50% mortality compared with wild-type (WT) littermates. Protein levels of NCX1, calsequestrin, ryanodine receptor, and α(1)- and α(2)-subunits of Na(+)-K(+)-ATPase were similar, but sarco(endo)plasmic reticulum Ca(2+)-ATPase was lower, whereas L-type Ca(2+) channels were higher in conS68E hearts. Resting membrane potential and action potential amplitude were similar, but action potential duration was dramatically prolonged in conS68E myocytes. Diastolic intracellular Ca(2+) ([Ca(2+)](i)) was higher, [Ca(2+)](i) transient and maximal contraction amplitudes were lower, and half-time of [Ca(2+)](i) transient decline was longer in conS68E myocytes. Intracellular Na(+) reached maximum within 3 min after isoproterenol addition, followed by decline in WT but not in conS68E myocytes. Na(+)/Ca(2+) exchange, L-type Ca(2+), Na(+)-K(+)-ATPase, and depolarization-activated K(+) currents were decreased in conS68E myocytes. At 22 wk, bradycardia and increased LV mass persisted in conS68E survivors. Despite comparable baseline CO, conS68E survivors at 22 wk exhibited decreased chronotropic, inotropic, and lusitropic responses to isoproterenol. We conclude that constitutive overexpression of S68E mutant was detrimental, both in terms of depressed cardiac function and increased arrhythmogenesis.
authors.affiliation: Division of Nephrology, Thomas Jefferson Univ., 833 Chestnut St., Suite 700, Philadelphia, PA 19107, USA.
authors.forename: Jianliang
authors.initials: J
authors.lastname: Song
authors.forename: Erhe
authors.initials: E
authors.lastname: Gao
authors.forename: Jufang
authors.initials: J
authors.lastname: Wang
authors.forename: Xue-Qian
authors.initials: XQ
authors.lastname: Zhang
authors.forename: Tung O
authors.initials: TO
authors.lastname: Chan
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Koch
authors.forename: Xiying
authors.initials: X
authors.lastname: Shang
authors.forename: Jeffrey I
authors.initials: JI
authors.lastname: Joseph
authors.forename: Blaise Z
authors.initials: BZ
authors.lastname: Peterson
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Feldman
authors.forename: Joseph Y
authors.initials: JY
authors.lastname: Cheung
mesh_terms: D000200:Action Potentials / Q000235:genetics / Q000502:physiology; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D001919:Bradycardia / Q000235:genetics / Q000378:metabolism / Q000401:mortality; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000502:physiology; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006333:Heart Failure / Q000235:genetics / Q000378:metabolism / Q000401:mortality; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D009200:Myocardial Contraction / Q000502:physiology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000235:genetics* / Q000378:metabolism
chemical_list: D020746:Calcium Channels, L-Type; D008565:Membrane Proteins; C499849:NCX1 protein, mouse; D010750:Phosphoproteins; D011943:Receptors, Adrenergic, beta; D019831:Sodium-Calcium Exchanger; C069141:phospholemman; D012964:Sodium; D011188:Potassium; D002118:Calcium
references.citation: Circ Res. 2003 Apr 4;92(6):609-16
references.pmid: 12623879
references.citation: Am J Physiol Cell Physiol. 2009 Jun;296(6):C1346-55
references.pmid: 19339511
references.citation: Am J Physiol Heart Circ Physiol. 2002 Aug;283(2):H576-83
references.pmid: 12124204
references.citation: Ann N Y Acad Sci. 2007 Mar;1099:119-34
references.pmid: 17446450
references.citation: Am J Physiol Heart Circ Physiol. 2001 Nov;281(5):H2079-88
references.pmid: 11668069
references.citation: Physiol Rev. 1999 Jul;79(3):763-854
references.pmid: 10390518
references.citation: Am J Physiol Cell Physiol. 2009 Apr;296(4):C911-21
references.pmid: 19158404
references.citation: J Biol Chem. 2005 May 20;280(20):19875-82
references.pmid: 15774479
references.citation: J Appl Physiol (1985). 2006 Jan;100(1):212-20
references.pmid: 16195392
references.citation: J Card Fail. 2007 May;13(4):318-29
references.pmid: 17517353
references.citation: Circ Res. 2004 Aug 6;95(3):225-7
references.pmid: 15297383
references.citation: Circ Res. 1998 Apr 6;82(6):657-65
references.pmid: 9546374
references.citation: Circ Res. 1997 Dec;81(6):1083-93
references.pmid: 9400390
references.citation: Annu Rev Physiol. 2000;62:111-33
references.pmid: 10845086
references.citation: J Appl Physiol (1985). 1999 Dec;87(6):2143-50
references.pmid: 10601161
references.citation: Circ Res. 2004 Sep 17;95(6):604-11
references.pmid: 15308581
references.citation: Physiol Rev. 2006 Jan;86(1):155-203
references.pmid: 16371597
references.citation: Am J Physiol Heart Circ Physiol. 2006 Nov;291(5):H2199-209
references.pmid: 16751288
references.citation: Cardiovasc Res. 2002 Mar;53(4):782-805
references.pmid: 11922890
references.citation: J Mol Cell Cardiol. 2002 Apr;34(4):389-400
references.pmid: 11991729
references.citation: Exerc Sport Sci Rev. 2004 Jul;32(3):83-9
references.pmid: 15243202
references.citation: Circ Res. 2000 Sep 29;87(7):581-7
references.pmid: 11009563
references.citation: Am J Physiol Heart Circ Physiol. 2002 Oct;283(4):H1616-26
references.pmid: 12234816
references.citation: J Physiol. 1998 Nov 1;512 ( Pt 3):651-67
references.pmid: 9769411
references.citation: Am J Physiol. 1992 Mar;262(3 Pt 1):C664-71
references.pmid: 1312780
references.citation: Circ Res. 2005 Aug 5;97(3):252-9
references.pmid: 16002746
references.citation: Genomics. 2000 Aug 15;68(1):41-56
references.pmid: 10950925
references.citation: J Biol Chem. 2006 Oct 20;281(42):32004-14
references.pmid: 16921169
references.citation: Cardiovasc Res. 1998 Feb;37(2):279-89
references.pmid: 9614485
references.citation: J Vasc Res. 2005 Nov-Dec;42(6):483-91
references.pmid: 16155364
references.citation: Cardiovasc Res. 2005 Jan 1;65(1):93-103
references.pmid: 15621037
references.citation: J Mol Cell Cardiol. 2002 Apr;34(4):369-73
references.pmid: 11991726
references.citation: J Gen Physiol. 1999 May;113(5):661-78
references.pmid: 10228181
references.citation: J Appl Physiol (1985). 2001 May;90(5):1720-8
references.pmid: 11299261
references.citation: Biophys J. 2010 Apr 7;98(7):1149-59
references.pmid: 20371314
references.citation: Am J Physiol Heart Circ Physiol. 2009 Aug;297(2):H590-601
references.pmid: 19525383
references.citation: Am J Physiol. 1995 Dec;269(6 Pt 1):C1464-73
references.pmid: 8572175
references.citation: Nat Med. 2000 May;6(5):482-3
references.pmid: 10802676
references.citation: Circ Res. 2001 Jun 8;88(11):1159-67
references.pmid: 11397782
references.citation: Am J Physiol Heart Circ Physiol. 2005 May;288(5):H2342-54
references.pmid: 15653756
references.citation: Am J Physiol Heart Circ Physiol. 2003 Jan;284(1):H225-33
references.pmid: 12388273
references.citation: J Biol Chem. 2006 Mar 24;281(12):7784-92
references.pmid: 16434394
references.citation: J Card Fail. 2006 Jun;12(5):392-8
references.pmid: 16762803
references.citation: Am J Physiol Heart Circ Physiol. 2011 Mar;300(3):H859-68
references.pmid: 21193587
references.citation: J Gen Physiol. 1997 Jun;109(6):717-29
references.pmid: 9222898
references.citation: Am J Physiol Heart Circ Physiol. 2000 Jul;279(1):H429-36
references.pmid: 10899083
references.citation: Am J Physiol Heart Circ Physiol. 2008 Oct;295(4):H1615-25
references.pmid: 18708446
references.citation: Am J Physiol Heart Circ Physiol. 2010 Mar;298(3):H807-15
references.pmid: 20008271
references.citation: Circ Res. 1999 Nov 26;85(11):1009-19
references.pmid: 10571531