scholarly journals Impairment of the Ubiquitin-Proteasome Pathway Is a Downstream Endoplasmic Reticulum Stress Response Induced by Extracellular Human Islet Amyloid Polypeptide and Contributes to Pancreatic  -Cell Apoptosis

Diabetes ◽  
2007 ◽  
Vol 56 (9) ◽  
pp. 2284-2294 ◽  
Author(s):  
S. Casas ◽  
R. Gomis ◽  
F. M. Gribble ◽  
J. Altirriba ◽  
S. Knuutila ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Islet Amyloid Polypeptide ◽  
Human Islet ◽  
Endoplasmic Reticulum Stress Response ◽  
Islet Amyloid ◽  
Pancreatic Cell ◽  
Ubiquitin Proteasome Pathway ◽  
Ubiquitin Proteasome ◽  
Proteasome Pathway

scholarly journals Analysis of the Protein Kinase A-Regulated Proteome ofCryptococcus neoformansIdentifies a Role for the Ubiquitin-Proteasome Pathway in Capsule Formation

mBio ◽  
2016 ◽  
Vol 7 (1) ◽  
Author(s):  
J. M. H. Geddes ◽  
M. Caza ◽  
D. Croll ◽  
N. Stoynov ◽  
L. J. Foster ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Kinase ◽  
Protein Kinase A ◽  
Camp Signaling ◽  
Ubiquitin Proteasome Pathway ◽  
Capsule Production ◽  
Life Threatening ◽  
Ubiquitin Proteasome ◽  
Proteasome Pathway ◽  
Kinase A

ABSTRACTThe opportunistic fungal pathogenCryptococcus neoformanscauses life-threatening meningitis in immunocompromised individuals. The expression of virulence factors, including capsule and melanin, is in part regulated by the cyclic-AMP/protein kinase A (cAMP/PKA) signal transduction pathway. In this study, we investigated the influence of PKA on the composition of the intracellular proteome to obtain a comprehensive understanding of the regulation that underpins virulence. Through quantitative proteomics, enrichment and bioinformatic analyses, and an interactome study, we uncovered a pattern of PKA regulation for proteins associated with translation, the proteasome, metabolism, amino acid biosynthesis, and virulence-related functions. PKA regulation of the ubiquitin-proteasome pathway inC. neoformansshowed a striking parallel with connections between PKA and protein degradation in chronic neurodegenerative disorders and other human diseases. Further investigation of proteasome function with the inhibitor bortezomib revealed an impact on capsule production as well as hypersusceptibility for strains with altered expression or activity of PKA. Parallel studies with tunicamycin also linked endoplasmic reticulum stress with capsule production and PKA. Taken together, the data suggest a model whereby expression of PKA regulatory and catalytic subunits and the activation of PKA influence proteostasis and the function of the endoplasmic reticulum to control the elaboration of the polysaccharide capsule. Overall, this study revealed both broad and conserved influences of the cAMP/PKA pathway on the proteome and identified proteostasis as a potential therapeutic target for the treatment of cryptococcosis.IMPORTANCEFungi cause life-threatening diseases, but very few drugs are available to effectively treat fungal infections. The pathogenic fungusCryptococcus neoformanscauses a substantial global burden of life-threatening meningitis in patients suffering from HIV/AIDS. An understanding of the mechanisms by which fungi deploy virulence factors to cause disease is critical for developing new therapeutic approaches. We employed a quantitative proteomic approach to define the changes in the protein complement that occur upon modulating the cAMP signaling pathway that regulates virulence inC. neoformans. This approach identified a conserved role for cAMP signaling in the regulation of the ubiquitin-proteasome pathway and revealed a link between this pathway and elaboration of a major virulence determinant, the polysaccharide capsule. Targeting the ubiquitin-proteasome pathway opens new therapeutic options for the treatment of cryptococcosis.

scholarly journals RNF170 Protein, an Endoplasmic Reticulum Membrane Ubiquitin Ligase, Mediates Inositol 1,4,5-Trisphosphate Receptor Ubiquitination and Degradation

2011 ◽  
Vol 286 (27) ◽  
pp. 24426-24433 ◽  
Author(s):  
Justine P. Lu ◽  
Yuan Wang ◽  
Danielle A. Sliter ◽  
Margaret M. P. Pearce ◽  
Richard J. H. Wojcikiewicz
Keyword(s):  
Endoplasmic Reticulum ◽  
Ubiquitin Ligase ◽  
Endoplasmic Reticulum Membrane ◽  
Ubiquitin Proteasome Pathway ◽  
Ubiquitin Ligase Activity ◽  
Inositol 1,4,5 Trisphosphate ◽  
Ubiquitin Proteasome ◽  
Proteasome Pathway ◽  
Membrane Spanning ◽  
Trisphosphate Receptor

Inositol 1,4,5-trisphosphate (IP3) receptors are endoplasmic reticulum membrane calcium channels that, upon activation, are degraded via the ubiquitin-proteasome pathway. While searching for novel mediators of IP3 receptor processing, we discovered that RNF170, an uncharacterized RING domain-containing protein, associates rapidly with activated IP3 receptors. RNF170 is predicted to have three membrane-spanning helices, is localized to the ER membrane, and possesses ubiquitin ligase activity. Depletion of endogenous RNF170 by RNA interference inhibited stimulus-induced IP3 receptor ubiquitination, and degradation and overexpression of a catalytically inactive RNF170 mutant suppressed stimulus-induced IP3 receptor processing. A substantial proportion of RNF170 is constitutively associated with the erlin1/2 (SPFH1/2) complex, which has been shown previously to bind to IP3 receptors immediately after their activation. Depletion of RNF170 did not affect the binding of the erlin1/2 complex to stimulated IP3 receptors, whereas erlin1/2 complex depletion inhibited RNF170 binding. These results suggest a model in which the erlin1/2 complex recruits RNF170 to activated IP3 receptors where it mediates IP3 receptor ubiquitination. Thus, RNF170 plays an essential role in IP3 receptor processing via the ubiquitin-proteasome pathway.

The ubiquitin-proteasome pathway of intracellular proteolysis

2002 ◽  
Vol 38 ◽  
pp. 51-63 ◽  
Author(s):  
Fergus J Doherty ◽  
Simon Dawson ◽  
R John Mayer
Keyword(s):  
Endoplasmic Reticulum ◽  
Kinase Activity ◽  
Covalent Attachment ◽  
Ubiquitin Chain ◽  
Ubiquitin Pathway ◽  
Ubiquitin Proteasome Pathway ◽  
Intracellular Proteins ◽  
Ubiquitin Proteasome ◽  
Proteasome Pathway ◽  
Intracellular Proteolysis

Intracellular proteins are targeted for degradation by the covalent attachment of chains of the small protein ubiquitin; a process known as ubiquitylation. Many proteins are phosphorylated prior to ubiquitylation, and therefore ubiquitylation and degradation of these proteins is regulated by kinase activity and signalling cascades. Many ubiquitylated proteins are degraded by the 26 S proteasome complex, which is found in the cytosol and nucleus. The 26 S proteasome consists of a 20 S core with proteolytic activity and 18 S regulatory complexes containing ATPases and ubiquitin-chain-binding proteins. Proteins degraded by the ubiquitin-proteasome pathway include cyclins and other regulators of the cell cycle, and transcription factors. Abnormal polypeptides are also degraded by the ubiquitin pathway, including abnormal polypeptides in the endoplasmic reticulum, which are translocated back out of the endoplasmic reticulum prior to ubiquitylation and degradation by the proteasome. The ubiquitin-proteasome pathway is implicated in numerous diseases including cancer and neurodegenerative diseases.

Human islet amyloid polypeptide accumulates at similar sites in islets of transgenic mice and humans

Diabetes ◽  
1994 ◽  
Vol 43 (5) ◽  
pp. 640-644 ◽  
Author(s):  
E. J. de Koning ◽  
J. W. Hoppener ◽  
J. S. Verbeek ◽  
C. Oosterwijk ◽  
K. L. van Hulst ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Islet Amyloid Polypeptide ◽  
Human Islet ◽  
Islet Amyloid ◽  
Human Islet Amyloid Polypeptide
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