scholarly journals PDE1 inhibition facilitates proteasomal degradation of misfolded proteins and protects against cardiac proteinopathy

2019 ◽  
Vol 5 (5) ◽  
pp. eaaw5870 ◽  
Author(s):  
Hanming Zhang ◽  
Bo Pan ◽  
Penglong Wu ◽  
Nirmal Parajuli ◽  
Mark D. Rekhter ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Ubiquitin Proteasome System ◽  
Proteasomal Degradation ◽  
Current Treatment ◽  
Misfolded Proteins ◽  
Dependent Protein Kinase ◽  
Selective Degradation ◽  
Proteotoxic Stress ◽  
Ubiquitin Proteasome ◽  
Dependent Protein

No current treatment targets cardiac proteotoxicity or can reduce mortality of heart failure (HF) with preserved ejection fraction (HFpEF). Selective degradation of misfolded proteins by the ubiquitin-proteasome system (UPS) is vital to the cell. Proteasome impairment contributes to HF. Activation of cAMP-dependent protein kinase (PKA) or cGMP-dependent protein kinase (PKG) facilitates proteasome functioning. Phosphodiesterase 1 (PDE1) hydrolyzes both cyclic nucleotides and accounts for most PDE activities in human myocardium. We report that PDE1 inhibition (IC86430) increases myocardial 26S proteasome activities and UPS proteolytic function in mice. Mice with CryABR120G-based proteinopathy develop HFpEF and show increased myocardial PDE1A expression. PDE1 inhibition markedly attenuates HFpEF, improves mouse survival, increases PKA-mediated proteasome phosphorylation, and reduces myocardial misfolded CryAB. Therefore, PDE1 inhibition induces PKA- and PKG-mediated promotion of proteasomal degradation of misfolded proteins and treats HFpEF caused by CryABR120G, representing a potentially new therapeutic strategy for HFpEF and heart disease with increased proteotoxic stress.

scholarly journals The Deubiquitylating Enzyme Ubp12 Regulates Rad23-Dependent Substrate Delivery at the Proteasome

2017 ◽  
Author(s):  
Daniela Gödderz ◽  
Nico P. Dantuma
Keyword(s):  
Dna Repair ◽  
Ubiquitin Proteasome System ◽  
Proteasomal Degradation ◽  
Misfolded Proteins ◽  
Proteotoxic Stress ◽  
Lysine Residues ◽  
Regulatory Link ◽  
Ubiquitin Proteasome ◽  
Summary Statement

AbstractThe consecutive actions of the ubiquitin-selective segregase Cdc48 and the ubiquitin shuttle factor Rad23 result in the delivery of ubiquitylated proteins at the proteasome. Here, we show that the deubiquitylating enzyme Ubp12 interacts with Cdc48 and regulates proteasomal degradation of Rad23-dependent substrates. Overexpression of Ubp12 results in stabilization of Rad23-dependent substrates. We show that Ubp12 removes short ubiquitin chains from the N-terminal ubiquitin-like domain (UbL) of Rad23. Preventing ubiquitylation of Rad23 by substitution of lysine residues within the UbL domain, Rad23UbLK0, does not affect the non-proteolytic role of Rad23 in DNA repair but causes an increase in ubiquitylated cargo bound to the UBA2 domains of Rad23 and recapitulates the stabilization of Rad23-dependent substrates observed upon overexpression of Ubp12. Expression of Rad23UbLK0or overexpression of Ubp12 impairs the ability of yeast to cope with proteotoxic stress consistent with inefficient clearance of misfolded proteins by the ubiquitin/proteasome system. Our data suggest that ubiquitylation of Rad23 plays a stimulatory role in facilitating the transfer of ubiquitylated substrates to the proteasome.Summary statementUbiquitylation of a ubiquitin shuttle factor regulates the delivery of substrates at the proteasome, uncovering a novel regulatory link between ubiquitin and proteasomal degradation.

Abstract 486: Down-regulation of type 1 cGMP-dependent Protein Kinase by the ubiquitin/proteasome pathway

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
NUPUR DEY ◽  
Jennifer L Busch ◽  
Sharron H Francis ◽  
Jackie D Corbin ◽  
Thomas M Lincoln
Keyword(s):  
Protein Kinase ◽  
26S Proteasome ◽  
Down Regulation ◽  
Dependent Protein Kinase ◽  
Ubiquitin Proteasome Pathway ◽  
Cgmp Dependent Protein Kinase ◽  
Ubiquitin Proteasome ◽  
Dependent Protein ◽  
Proteasome Pathway

Type 1 cGMP-dependent protein kinase (PKG-I) is a widely expressed serine/threonine protein kinase, and is a major mediator of nitric oxide (NO) signaling in vascular smooth muscle cells (VSMC). PKG-I level is highly variable in VSMC and several studies have shown that atherogenic inflammatory cytokines lower the steady-statel levels of PKG-I. The mechanism of action of down-regulation is not well defined, but induction of type II NO synthase (iNOS) and subsequent persistent elevation of cGMP appear to contribute to PKG-I down regulation. In the present study, we examined the role of the ubiquitin/proteasome pathway in PKG-Iα down-regulation in response to elevated cGMP. Incubation of cultured VSMC with 8-Br-cGMP for 6–12 hr lowered PKG-I expression as assessed by western blotting. To further examine the mechanism, Cos7 cells, which do not express PKG-I mRNA or protein, were transfected with PKG-Iα/pcDNA vector and incubated with 8-Br-cGMP. 8-Br-cGMP suppressed PKG-Iα protein level in Cos7 cells (half-maximal concentration = 250 μM). Pretreatment of these cells with the proteasome inhibitor, MG132, followed by 8-Br-cGMP treatment prevented the decline suggesting the involvement of the ubiquitin/26S proteasome pathway. Immunoprecipitation of PKG-I followed by immunoblotting with anti-ubiquitin revealed multiple ubiquitinated PKG bands in the 8-Br-cGMP treated samples but not in untreated samples. Ubiquitination and down-regulation were also inhibited by the specific PKG-I catalytic inhibitor DT-2, suggesting the possible involvement of PKG autophosphorylation in the 8-Br-cGMP induced down-regulation. Mutation of the PKG-Iα autophosphorylation sites to alanines was performed to identify the phosphorylated site responsible for cGMP-dependent ubiquitination. In contrast to wild type PKG-Iα, PKG-Iα S64A, but not the S50A mutant, was not down-regulated by 8-Br-cGMP suggesting that autophosphorylation of serine-64 is required for the ubiquitination and down-regulation of PKG-I. Autophosphorylation and cGMP-mediated down-regulation of PKG-I may be an important mechanism to control excess cGMP signaling in VSMC.

scholarly journals Parkin-mediated ubiquitin signalling in aggresome formation and autophagy

2010 ◽  
Vol 38 (1) ◽  
pp. 144-149 ◽  
Author(s):  
Lih-Shen Chin ◽  
James A. Olzmann ◽  
Lian Li
Keyword(s):  
Protein Misfolding ◽  
Current Knowledge ◽  
Ubiquitin Proteasome System ◽  
Misfolded Proteins ◽  
Proteotoxic Stress ◽  
Ubiquitin Proteasome ◽  
Autophagy Pathway ◽  
Aggresome Formation ◽  
Protein Misfolding And Aggregation ◽  
Cellular Defence

Understanding how cells handle and dispose of misfolded proteins is of paramount importance because protein misfolding and aggregation underlie the pathogenesis of many neurodegenerative disorders, including PD (Parkinson's disease) and Alzheimer's disease. In addition to the ubiquitin–proteasome system, the aggresome–autophagy pathway has emerged as another crucial cellular defence system against toxic build-up of misfolded proteins. In contrast with basal autophagy that mediates non-selective, bulk clearance of misfolded proteins along with normal cellular proteins and organelles, the aggresome–autophagy pathway is increasingly recognized as a specialized type of induced autophagy that mediates selective clearance of misfolded and aggregated proteins under the conditions of proteotoxic stress. Recent evidence implicates PD-linked E3 ligase parkin as a key regulator of the aggresome–autophagy pathway and indicates a signalling role for Lys63-linked polyubiquitination in the regulation of aggresome formation and autophagy. The present review summarizes the current knowledge of the aggresome–autophagy pathway, its regulation by parkin-mediated Lys63-linked polyubiquitination, and its dysfunction in neurodegenerative diseases.

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