title: Proteome dynamics and proteome function of cardiac 19S proteasomes.
abstract: Myocardial proteasomes are comprised of 20S core particles and 19S regulatory particles, which together carry out targeted degradation of cardiac proteins. The 19S complex is unique among the regulators of proteasomes in that it affects both the capacity and specificity of protein degradation. However, a comprehensive molecular characterization of cardiac 19S complexes is lacking. In this investigation, we tailored a multidimensional chromatography-based purification strategy to isolate structurally intact and functionally viable 19S complexes from murine hearts. Two distinct subpopulations of 19S complexes were isolated based upon (1) potency of activating 20S proteolytic activity, and (2) molecular composition using a combination of immuno-detection, two-dimensional-differential gel electrophoresis, and MS-based approaches. Heat shock protein 90 (Hsp90) was identified to be characteristic to 19S subpopulation I. The physical interaction of Hsp90 with 19S complexes was demonstrated via multiple approaches. Inhibition of Hsp90 activity using geldanamycin or BIIB021 potentiated the ability of subpopulation I to activate 20S proteasomes in the murine heart, thus demonstrating functional specificity of Hsp90 in subpopulation I. This investigation has advanced our understanding of the molecular heterogeneity of cardiac proteasomes by identifying molecularly and functionally distinct cardiac 19S complexes. The preferential association of Hsp90 with 19S subpopulation I unveils novel targets for designing proteasome-based therapeutic interventions for combating cardiac disease.
authors.affiliation: Department of Physiology and Medicine, Division of Cardiology, University of California at Los Angeles, UCLA School of Medicine, Los Angeles, California 90095, USA.
authors.forename: Ding
authors.initials: D
authors.lastname: Wang
authors.forename: Chenggong
authors.initials: C
authors.lastname: Zong
authors.forename: Myong-chul
authors.initials: MC
authors.lastname: Koag
authors.forename: Yueju
authors.initials: Y
authors.lastname: Wang
authors.forename: Oliver
authors.initials: O
authors.lastname: Drews
authors.forename: Caiyun
authors.initials: C
authors.lastname: Fang
authors.forename: Sarah B
authors.initials: SB
authors.lastname: Scruggs
authors.forename: Peipei
authors.initials: P
authors.lastname: Ping
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002853:Chromatography, Liquid; D004789:Enzyme Activation; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D018841:HSP90 Heat-Shock Proteins; D020543:Proteome; D046988:Proteasome Endopeptidase Complex; C119011:26S proteasome non-ATPase regulatory subunit 13