Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: KEGG:D03276 (Parkin)
1,863 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The parkin gene codes for a 465-amino acid protein which, when mutated, results in autosomal recessive juvenile parkinsonism (AR-JP). Symptoms of AR-JP are similar to those of idiopathic Parkinson's disease, with the notable exception being the early onset of AR-JP. We have cloned and expressed human Parkin in Escherichia coli and have examined Parkin-mediated ubiquitination in an in vitro ubiquitination assay using purified recombinant proteins. We found that Parkin has E3 ubiquitin ligase activity in this system, demonstrating for the first time that the E3 activity is an intrinsic function of the Parkin protein and does not require posttranslational modification or association with cellular proteins other than an E2 (human Ubc4 E2 was utilized in this ubiquitination assay). Mutagenesis of individual elements of the conserved RING TRIAD domain indicated that at least two elements were required for ubiquitin ligase activity and suggested a functional cooperation between the RING finger elements. Since the activity assays were conducted with recombinant proteins purified from E. coli, this is the first time TRIAD element interaction has been demonstrated as an intrinsic feature of Parkin E3 activity.
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PMID:E3 ubiquitin-protein ligase activity of Parkin is dependent on cooperative interaction of RING finger (TRIAD) elements. 1154 85

Septins are GTPases required for the completion of cytokinesis in a variety of organisms, yet their role in this process is not known. Septins may have additional functions since the mammalian septin CDCrel-1 is predominantly expressed in the nervous system, a largely postmitotic tissue. While relatively little is known about the function of this protein, we have previously shown that it is involved in regulated secretion. In addition, the gene encoding this protein maps to a locus often deleted in velo-cardiofacial and DiGeorge syndromes, and CDCrel-1 has recently been shown to be a direct target of the E3 ubiquitin ligase activity of Parkin, a causative agent in autosomal recessive forms of Parkinson's disease. Here we show that CDCrel-1 expression rises at the time of synaptic maturation and that CDCrel-1 is present in a complex that includes the septins Nedd5 and CDC10. To investigate its function in the nervous system, we generated homozygotic CDCrel-1 null mice and showed that these mice appear normal with respect to synaptic properties and hippocampal neuron growth in vitro. Moreover, we found that while the expression of a number of synaptic proteins is not affected in the CDCrel-1 mutant mice, the expression of other septins is altered. Together, these data suggest that CDCrel-1 is not essential for neuronal development or function, and that changes in expression of other septins may account for its functional redundancy.
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PMID:The septin CDCrel-1 is dispensable for normal development and neurotransmitter release. 1173 49

Unfolded Pael receptor (Pael-R) is a substrate of the E3 ubiquitin ligase Parkin. Accumulation of Pael-R in the endoplasmic reticulum (ER) of dopaminergic neurons induces ER stress leading to neurodegeneration. Here, we show that CHIP, Hsp70, Parkin, and Pael-R formed a complex in vitro and in vivo. The amount of CHIP in the complex was increased during ER stress. CHIP promoted the dissociation of Hsp70 from Parkin and Pael-R, thus facilitating Parkin-mediated Pael-R ubiquitination. Moreover, CHIP enhanced Parkin-mediated in vitro ubiquitination of Pael-R in the absence of Hsp70. Furthermore, CHIP enhanced the ability of Parkin to inhibit cell death induced by Pael-R. Taken together, these results indicate that CHIP is a mammalian E4-like molecule that positively regulates Parkin E3 activity.
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PMID:CHIP is associated with Parkin, a gene responsible for familial Parkinson's disease, and enhances its ubiquitin ligase activity. 1215 Sep 7

Parkin gene mutations have been implicated in autosomal-recessive early-onset parkinsonism and lead to specific degeneration of dopaminergic neurons in midbrain. To investigate the role of Parkin in neuronal cell death, we overproduced this protein in PC12 cells in an inducible manner. In this cell line, neuronally differentiated by nerve growth factor, Parkin overproduction protected against cell death mediated by ceramide, but not by a variety of other cell death inducers (H(2)O(2), 4-hydroxynonenal, rotenone, 6-OHDA, tunicamycin, 2-mercaptoethanol and staurosporine). Protection was abrogated by the proteasome inhibitor epoxomicin and disease-causing variants, indicating that it was mediated by the E3 ubiquitin ligase activity of Parkin. Interestingly, Parkin acted by delaying mitochondrial swelling and subsequent cytochrome c release and caspase-3 activation observed in ceramide-mediated cell death. Subcellular fractionation demonstrated enrichment of Parkin in the mitochondrial fraction and its association with the outer mitochondrial membrane. Together, these results suggest that Parkin may promote the degradation of substrates localized in mitochondria and involved in the late mitochondrial phase of ceramide-mediated cell death. Loss of this function may underlie the degeneration of nigral dopaminergic neurons in patients with Parkin mutations.
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PMID:Parkin prevents mitochondrial swelling and cytochrome c release in mitochondria-dependent cell death. 1258 99

Parkin, a product of the causative gene of autosomal-recessive juvenile parkinsonism (AR-JP), is a RING-type E3 ubiquitin ligase and has an amino-terminal ubiquitin-like (Ubl) domain. Although a single mutation that causes an Arg to Pro substitution at position 42 of the Ubl domain (the Arg 42 mutation) has been identified in AR-JP patients, the function of this domain is not clear. In this study, we determined the three-dimensional structure of the Ubl domain of parkin by NMR, in particular by extensive use of backbone (15)N-(1)H residual dipolar-coupling data. Inspection of chemical-shift-perturbation data showed that the parkin Ubl domain binds the Rpn10 subunit of 26S proteasomes via the region of parkin that includes position 42. Our findings suggest that the Arg 42 mutation induces a conformational change in the Rpn10-binding site of Ubl, resulting in impaired proteasomal binding of parkin, which could be the cause of AR-JP.
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PMID:Parkin binds the Rpn10 subunit of 26S proteasomes through its ubiquitin-like domain. 1263 50

Parkin, an E3 ubiquitin ligase that degrades proteins with aberrant conformations, is associated with autosomal recessive juvenile Parkinsonism (AR-JP). The molecular basis of selective neuronal death in AR-JP is unknown. Here we show in an organismal system that panneuronal expression of Parkin substrate Pael-R causes age-dependent selective degeneration of Drosophila dopaminergic (DA) neurons. Coexpression of Parkin degrades Pael-R and suppresses its toxicity, whereas interfering with endogenous Drosophila Parkin function promotes Pael-R accumulation and augments its toxicity. Furthermore, overexpression of Parkin can mitigate alpha-Synuclein-induced neuritic pathology and suppress its toxicity. Our study implicates Parkin as a central player in the molecular pathway of Parkinson's disease (PD) and suggests that manipulating Parkin expression may provide a novel avenue of PD therapy.
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PMID:Parkin suppresses dopaminergic neuron-selective neurotoxicity induced by Pael-R in Drosophila. 1267 Apr 21

Parkin, the most commonly mutated gene in familial Parkinson's disease, encodes an E3 ubiquitin ligase. A number of candidate substrates have been identified for parkin ubiquitin ligase action including CDCrel-1, o-glycosylated alpha-synuclein, Pael-R, and synphilin-1. We now show that parkin promotes the ubiquitination and degradation of an expanded polyglutamine protein. Overexpression of parkin reduces aggregation and cytotoxicity of an expanded polyglutamine ataxin-3 fragment. Using a cellular proteasome indicator system based on a destabilized form of green fluorescent protein, we demonstrate that parkin reduces proteasome impairment and caspase-12 activation induced by an expanded polyglutamine protein. Parkin forms a complex with the expanded polyglutamine protein, heat shock protein 70 (Hsp70) and the proteasome, which may be important for the elimination of the expanded polyglutamine protein. Hsp70 enhances parkin binding and ubiquitination of expanded polyglutamine protein in vitro suggesting that Hsp70 may help to recruit misfolded proteins as substrates for parkin E3 ubiquitin ligase activity. We speculate that parkin may function to relieve endoplasmic reticulum stress by preserving proteasome activity in the presence of misfolded proteins. Loss of parkin function and the resulting proteasomal impairment may contribute to the accumulation of toxic aberrant proteins in neurodegenerative diseases including Parkinson's disease.
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PMID:Parkin facilitates the elimination of expanded polyglutamine proteins and leads to preservation of proteasome function. 1267 55

Autosomal-recessive juvenile parkinsonism (AR-JP) is caused by mutations in the parkin gene. Parkin protein is characterized by a ubiquitin-like domain at its NH(2) terminus and by two RING finger motifs and one IBR (in between RING finger) motif at its COOH-terminus (RING-IBR-RING). We showed that the parkin protein is an E3 ubiquitin ligase, which binds to ubiquitin-conjugating enzymes (E2s) through its RING-IBR-RING motif. The pathogenesis of AR-JP, therefore, was hypothesized to be accumulation of unidentified neurotoxic protein (a substrate of parkin). On the basis of this hypothesis, the substrate of parkin was sought using a yeast two-hybrid system. A putative G protein-coupled transmembrane polypeptide, named Pael (parkin-associated endothelin receptor-like) receptor, was identified as a parkin binding protein. When overexpressed in cells, this receptor tends to become unfolded, insoluble, and ubiquitinated. The insoluble Pael receptor leads to endoplasmic reticulum (ER) stress-induced cell death. Parkin specifically ubiquitinates this receptor in the presence of ER-resident E2s and promotes the degradation of unfolded Pael receptor, resulting in suppression of the cell death induced by the accumulation of unfolded Pael receptor in the ER. Moreover, the insoluble form of Pael receptor accumulates in the brain of AR-JP patients. This protein is highly expressed in the dopaminergic neurons in the substantia nigra, which is specifically affected in Parkinson's disease; although it is also widely expressed in oligodendroglias in the fiber tract. In conclusion, we showed that the accumulation of unfolded Pael receptor (a substrate of parkin) may cause selective death of dopaminergic neurons in AR-JP.
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PMID:Parkin and endoplasmic reticulum stress. 1284 78

Loss-of-function mutations in parkin are the major cause of early-onset familial Parkinson's disease. To investigate the pathogenic mechanism by which loss of parkin function causes Parkinson's disease, we generated a mouse model bearing a germline disruption in parkin. Parkin-/- mice are viable and exhibit grossly normal brain morphology. Quantitative in vivo microdialysis revealed an increase in extracellular dopamine concentration in the striatum of parkin-/- mice. Intracellular recordings of medium-sized striatal spiny neurons showed that greater currents are required to induce synaptic responses, suggesting a reduction in synaptic excitability in the absence of parkin. Furthermore, parkin-/- mice exhibit deficits in behavioral paradigms sensitive to dysfunction of the nigrostriatal pathway. The number of dopaminergic neurons in the substantia nigra of parkin-/- mice, however, is normal up to the age of 24 months, in contrast to the substantial loss of nigral neurons characteristic of Parkinson's disease. Steady-state levels of CDCrel-1, synphilin-1, and alpha-synuclein, which were identified previously as substrates of the E3 ubiquitin ligase activity of parkin, are unaltered in parkin-/- brains. Together these findings provide the first evidence for a novel role of parkin in dopamine regulation and nigrostriatal function, and a non-essential role of parkin in the survival of nigral neurons in mice.
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PMID:Parkin-deficient mice exhibit nigrostriatal deficits but not loss of dopaminergic neurons. 1293 Aug 22

Autosomal recessive juvenile parkinsonism (AR-JP) is caused by mutations of the parkin gene. Parkin is an E3 ubiquitin ligase that specifically recognizes its substrate protein, promoting its ubiquitination and subsequent degradation. Accordingly, we hypothesized that AR-JP may be caused by accumulation of an unidentified neurotoxic protein, which is a substrate of parkin. Based on this hypothesis, we cloned parkin-binding protein using a yeast two-hybrid system and identified a putative G protein-coupled receptor protein,which we named the Pael receptor (Pael-R). When overexpressed in cells, this receptor became unfolded, insoluble, and ubiquitinated. Accumulation of the insoluble Pael-R subsequently led to endoplasmic reticulum (ER) stress-induced cell death. Parkin specifically ubiquitinates the unfolded Pael-R and promotes its degradation, resulting in suppression of cell death induced by the accumulation of unfolded Pael-R. Moreover, insoluble Pael-R accumulates in the brains of AR-JP patients. It is highly expressed by the dopaminergic neurons of the substantia nigra, strongly suggesting that accumulation of unfolded Pael-R may lead to selective death of dopaminergic neurons in AR-JP.Recently, we identified Hsp70 and its co-chaperone CHIP as novel parkin-binding partners. We found that CHIP enhanced parkinmediated ubiquitination of Pael-R. In concert with Hsp70, CHIP also enhanced the ability of parkin to inhibit cell death induced by Pael-R, indicating that CHIP and Hsp70 are both co-factors of parkin.
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PMID:Pael receptor, endoplasmic reticulum stress, and Parkinson's disease. 1457 21


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