title: Cardiomyocyte ryanodine receptor degradation by chaperone-mediated autophagy.
abstract: OBJECTIVE
  Chaperone-mediated autophagy (CMA) is a selective mechanism for the degradation of soluble cytosolic proteins bearing the sequence KFERQ. These proteins are targeted by chaperones and delivered to lysosomes where they are translocated into the lysosomal lumen and degraded via the lysosome-associated membrane protein type 2A (LAMP-2A). Mutations in LAMP2 that inhibit autophagy result in Danon disease characterized by hypertrophic cardiomyopathy. The ryanodine receptor type 2 (RyR2) plays a key role in cardiomyocyte excitation-contraction and its dysfunction can lead to cardiac failure. Whether RyR2 is degraded by CMA is unknown.
  
  
  RESULTS
  To induce CMA, cultured neonatal rat cardiomyocytes were treated with geldanamycin (GA) to promote protein degradation through this pathway. GA increased LAMP-2A levels together with its redistribution and colocalization with Hsc70 in the perinuclear region, changes indicative of CMA activation. The inhibition of lysosomes but not proteasomes prevented the loss of RyR2. The recovery of RyR2 content after incubation with GA by siRNA targeting LAMP-2A suggests that RyR2 is degraded via CMA. In silico analysis also revealed that the RyR2 sequence harbours six KFERQ motifs which are required for the recognition Hsc70 and its degradation via CMA. Our data suggest that presenilins are involved in RyR2 degradation by CMA.
  
  
  CONCLUSIONS
  These findings are consistent with a model in which oxidative damage of the RyR2 targets it for turnover by presenilins and CMA, which could lead to removal of damaged or leaky RyR2 channels.
authors: Centro de Estudios Moleculares de la Célula, Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago 8380492, Chile. zpedrozo@med.uchile.cl
authors: Zully
authors: Z
authors: Pedrozo
authors: Natalia
authors: N
authors: Torrealba
authors: Carolina
authors: C
authors: Fernández
authors: Damian
authors: D
authors: Gatica
authors: Barbra
authors: B
authors: Toro
authors: Clara
authors: C
authors: Quiroga
authors: Andrea E
authors: AE
authors: Rodriguez
authors: Gina
authors: G
authors: Sanchez
authors: Thomas G
authors: TG
authors: Gillette
authors: Joseph A
authors: JA
authors: Hill
authors: Paulina
authors: P
authors: Donoso
authors: Sergio
authors: S
authors: Lavandero
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001343:Autophagy; D016227:Benzoquinones / Q000494:pharmacology; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D008247:Lysosomes / Q000378:metabolism; D018832:Molecular Chaperones / Q000502:physiology*; D008969:Molecular Sequence Data; D017202:Myocardial Ischemia / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018384:Oxidative Stress; D053763:Presenilins / Q000502:physiology; D046988:Proteasome Endopeptidase Complex / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000378:metabolism*
chemical_list: D016227:Benzoquinones; D047029:Lactams, Macrocyclic; D018832:Molecular Chaperones; D053763:Presenilins; D019837:Ryanodine Receptor Calcium Release Channel; D046988:Proteasome Endopeptidase Complex; C001277:geldanamycin
references: Proc Natl Acad Sci U S A. 2011 Aug 9;108(32):13258-63
references: 21788490
references: FASEB J. 2005 Dec;19(14):2069-71
references: 16204356
references: Biochim Biophys Acta. 2010 Mar;1802(3):356-62
references: 20026269
references: Autophagy. 2007 Jul-Aug;3(4):295-9
references: 17404494
references: Am J Physiol. 1988 Oct;255(4 Pt 2):H917-28
references: 3177681
references: Anal Biochem. 1972 Aug;48(2):422-7
references: 4115981
references: Cell Mol Life Sci. 2008 May;65(9):1311-34
references: 18239854
references: J Biol Chem. 2002 Jul 12;277(28):25480-5
references: 11983711
references: FEBS Lett. 2010 Apr 2;584(7):1399-404
references: 20026330
references: J Biol Chem. 1997 Aug 1;272(31):19115-24
references: 9235900
references: Cell Mol Life Sci. 2011 Mar;68(5):749-63
references: 20976518
references: Cardiovasc Res. 2006 Jan;69(1):152-63
references: 16125156
references: Mol Biol Cell. 2004 Nov;15(11):4829-40
references: 15331765
references: J Cell Biol. 2009 May 18;185(4):629-39
references: 19433452
references: Mol Biol Cell. 2008 May;19(5):2179-92
references: 18337468
references: Methods Enzymol. 2009;452:297-324
references: 19200890
references: FASEB J. 2009 Oct;23(10):3383-92
references: 19509306
references: J Mol Cell Cardiol. 2004 Jul;37(1):101-10
references: 15242740
references: Antioxid Redox Signal. 2006 Jan-Feb;8(1-2):152-62
references: 16487049
references: J Appl Physiol (1985). 2005 Sep;99(3):999-1005
references: 15879166
references: J Biol Chem. 2003 Sep 12;278(37):35231-40
references: 12842893
references: J Mol Cell Cardiol. 2003 Dec;35(12):1429-37
references: 14654369
references: Chem Res Toxicol. 2006 Mar;19(3):376-81
references: 16544941
references: Circ Res. 2010 Apr 2;106(6):1022-34
references: 20360265
references: Front Biosci (Landmark Ed). 2011 Jan 01;16:553-67
references: 21196188
references: Mol Aspects Med. 2006 Oct-Dec;27(5-6):444-54
references: 16978688
references: J Mol Med (Berl). 2004 Aug;82(8):488-99
references: 15168026
references: Biomed Pharmacother. 2010 Mar;64(3):184-90
references: 20053523
references: Am J Physiol. 1999 Aug;277(2):H584-94
references: 10444483
references: Autophagy. 2005 Oct-Dec;1(3):141-5
references: 16874031
references: Biophys J. 1998 Mar;74(3):1263-77
references: 9512024
references: Neurosci Lett. 2002 Mar 22;321(3):187-91
references: 11880203
references: Nature. 2002 Jan 10;415(6868):198-205
references: 11805843
references: J Biol Chem. 2008 Aug 29;283(35):23542-56
references: 18566453