Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
Add more filters










Database
Language
Publication year range
1.
Cell Death Dis ; 4: e873, 2013 Oct 24.
Article in English | MEDLINE | ID: mdl-24157867

ABSTRACT

Autophagy is a critical regulator of organellar homeostasis, particularly of mitochondria. Upon the loss of membrane potential, dysfunctional mitochondria are selectively removed by autophagy through recruitment of the E3 ligase Parkin by the PTEN-induced kinase 1 (PINK1) and subsequent ubiquitination of mitochondrial membrane proteins. Mammalian sequestrome-1 (p62/SQSTM1) is an autophagy adaptor, which has been proposed to shuttle ubiquitinated cargo for autophagic degradation downstream of Parkin. Here, we show that loss of ref(2)P, the Drosophila orthologue of mammalian P62, results in abnormalities, including mitochondrial defects and an accumulation of mitochondrial DNA with heteroplasmic mutations, correlated with locomotor defects. Furthermore, we show that expression of Ref(2)P is able to ameliorate the defects caused by loss of Pink1 and that this depends on the presence of functional Parkin. Finally, we show that both the PB1 and UBA domains of Ref(2)P are crucial for mitochondrial clustering. We conclude that Ref(2)P is a crucial downstream effector of a pathway involving Pink1 and Parkin and is responsible for the maintenance of a viable pool of cellular mitochondria by promoting their aggregation and autophagic clearance.


Subject(s)
Drosophila Proteins/genetics , Drosophila Proteins/metabolism , Drosophila melanogaster/metabolism , Mitochondria/pathology , Mutation/genetics , Nuclear Proteins/metabolism , Protein Serine-Threonine Kinases/genetics , Suppression, Genetic , Ubiquitin-Protein Ligases/metabolism , Animals , Autophagy , DNA, Mitochondrial/metabolism , DNA-Binding Proteins , Drosophila melanogaster/ultrastructure , Longevity , Mitochondria/metabolism , Motor Activity , Phenotype
2.
Cell Death Differ ; 19(8): 1308-16, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22301916

ABSTRACT

Protein misfolding has a key role in several neurological disorders including Parkinson's disease. Although a clear mechanism for such proteinopathic diseases is well established when aggregated proteins accumulate in the cytosol, cell nucleus, endoplasmic reticulum and extracellular space, little is known about the role of protein aggregation in the mitochondria. Here we show that mutations in both human and fly PINK1 result in higher levels of misfolded components of respiratory complexes and increase in markers of the mitochondrial unfolded protein response. Through the development of a genetic model of mitochondrial protein misfolding employing Drosophila melanogaster, we show that the in vivo accumulation of an unfolded protein in mitochondria results in the activation of AMP-activated protein kinase-dependent autophagy and phenocopies of pink1 and parkin mutants. Parkin expression acts to clear mitochondria with enhanced levels of misfolded proteins by promoting their autophagic degradation in vivo, and refractory to Sigma P (ref(2)P), the Drosophila orthologue of mammalian p62, is a critical downstream effector of this quality control pathway. We show that in flies, a pathway involving pink1, parkin and ref(2)P has a role in the maintenance of a viable pool of cellular mitochondria by promoting organellar quality control.


Subject(s)
Drosophila Proteins/genetics , Drosophila melanogaster/genetics , Mitochondrial Proteins/genetics , Animals , Animals, Genetically Modified , Drosophila Proteins/metabolism , Drosophila melanogaster/enzymology , Drosophila melanogaster/metabolism , HEK293 Cells , Humans , Mitochondria/enzymology , Mitochondrial Proteins/metabolism , Protein Folding , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Protein Transport , Ubiquitin-Protein Ligases/genetics , Ubiquitin-Protein Ligases/metabolism
3.
Cell Death Differ ; 15(2): 274-82, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18034188

ABSTRACT

Some chemotherapeutic agents can elicit apoptotic cancer cell death, thereby activating an anticancer immune response that influences therapeutic outcome. We previously reported that anthracyclins are particularly efficient in inducing immunogenic cell death, correlating with the pre-apoptotic exposure of calreticulin (CRT) on the plasma membrane surface of anthracyclin-treated tumor cells. Here, we investigated the role of cellular Ca(2+) homeostasis on CRT exposure. A neuroblastoma cell line (SH-SY5Y) failed to expose CRT in response to anthracyclin treatment. This defect in CRT exposure could be overcome by the overexpression of Reticulon-1C, a manipulation that led to a decrease in the Ca(2+) concentration within the endoplasmic reticulum lumen. The combination of Reticulon-1C expression and anthracyclin treatment yielded more pronounced endoplasmic reticulum Ca(2+) depletion than either of the two manipulations alone. Chelation of intracellular (and endoplasmic reticulum) Ca(2+), targeted expression of the ligand-binding domain of the IP(3) receptor and inhibition of the sarco-endoplasmic reticulum Ca(2+)-ATPase pump reduced endoplasmic reticulum Ca(2+) load and promoted pre-apoptotic CRT exposure on the cell surface, in SH-SY5Y and HeLa cells. These results provide evidence that endoplasmic reticulum Ca(2+) levels control the exposure of CRT.


Subject(s)
Anthracyclines/pharmacology , Calcium/metabolism , Calreticulin/metabolism , Cell Membrane/metabolism , Endoplasmic Reticulum/metabolism , Nerve Tissue Proteins/metabolism , Apoptosis , Brefeldin A/pharmacology , Cell Line, Tumor , HeLa Cells , Homeostasis , Humans , Protein Synthesis Inhibitors/pharmacology
SELECTION OF CITATIONS
SEARCH DETAIL
...