Parkin mediates the degradation-independent ubiquitination of Hsp70

• Published in: Journal of neurochemistry Vol. 105; no. 5; pp. 1806 - 1819
• Main Authors: Moore, Darren J, West, Andrew B, Dikeman, Dustin A, Dawson, Valina L, Dawson, Ted M
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.06.2008; Blackwell Publishing Ltd; Blackwell
• Subjects: Aged; autosomal recessive juvenile-onset parkinsonism; Biochemistry; Biological and medical sciences; Brain; Brain - enzymology; Brain - pathology; Brain - physiology; Cell Line; Cell Line, Tumor; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; enzymology; Gene expression; genetics; HSP70 Heat-Shock Proteins; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; Humans; Medical sciences; metabolism; Mutation; Nervous system (semeiology, syndromes); Nervous system as a whole; Neurology; PARK2; parkin; Parkinson disease; Parkinson Disease - genetics; Parkinson Disease - metabolism; Parkinson Disease - pathology; Parkinson's disease; parkinsonism; pathology; physiology; Proteins; Ubiquitin; Ubiquitin - genetics; Ubiquitin - metabolism; Ubiquitin-Protein Ligases; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - physiology; ubiquitination; Ubiquitin; Modification; Parkinson's disease; Central nervous system; Parkinson disease; PARK2; Encephalon; Gene; Ligases; Degenerative disease; Ubiquitin-protein ligase; Nervous system diseases; Carbon-nitrogen ligases; parkin; Enzyme; Chaperone; autosomal recessive juvenile-onset parkinsonism; In vitro; Steady state; Protein; Cerebral disorder; Parkinsonism; Substrate; ubiquitination; Central nervous system disease; Lewy body dementia; Mutation; Extrapyramidal syndrome
• ISSN: 0022-3042; 1471-4159; 1471-4159
• DOI: 10.1111/j.1471-4159.2008.05261.x

Mutations in the parkin gene cause autosomal recessive, juvenile-onset parkinsonism. Parkin is an E3 ubiquitin ligase that mediates the ubiquitination of protein substrates. Disease-associated mutations cause a loss-of-function of parkin which may compromise the poly-ubiquitination and proteasomal degradation of specific protein substrates, potentially leading to their deleterious accumulation. Here, we identify the molecular chaperones, Hsp70 and Hsc70, as substrates for parkin. Parkin mediates the ubiquitination of Hsp70 both in vitro and in cultured cells. Parkin interacts with Hsp70 via its second RING finger domain and mutations in/near this domain compromise Hsp70 ubiquitination. Ubiquitination of Hsp70 fails to alter its steady-state levels or turnover, nor does it promote its proteasomal degradation. Consistent with this observation, Hsp70 levels remain unaltered in brains from parkin-deficient autosomal recessive, juvenile-onset parkinsonism subjects, whereas alternatively, Hsp70 levels are elevated in the detergent-insoluble fraction of sporadic Parkinson's disease/dementia with Lewy bodies brains. Parkin mediates the multiple mono-ubiquitination of Hsp70/Hsc70 consistent with a degradation-independent role for this ubiquitin modification. Our observations support a novel functional relationship between parkin and Hsc/Hsp70 and support the notion that parkin is a multi-purpose E3 ubiquitin ligase capable of modifying proteins either via attachment of alternatively linked poly-ubiquitin chains or through multiple mono-ubiquitination to achieve alternate biological outcomes.