ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2016-03-24
    Description: (beta-)Arrestins are important regulators of G-protein-coupled receptors (GPCRs). They bind to active, phosphorylated GPCRs and thereby shut off 'classical' signalling to G proteins, trigger internalization of GPCRs via interaction with the clathrin machinery and mediate signalling via 'non-classical' pathways. In addition to two visual arrestins that bind to rod and cone photoreceptors (termed arrestin1 and arrestin4), there are only two (non-visual) beta-arrestin proteins (beta-arrestin1 and beta-arrestin2, also termed arrestin2 and arrestin3), which regulate hundreds of different (non-visual) GPCRs. Binding of these proteins to GPCRs usually requires the active form of the receptors plus their phosphorylation by G-protein-coupled receptor kinases (GRKs). The binding of receptors or their carboxy terminus as well as certain truncations induce active conformations of (beta-)arrestins that have recently been solved by X-ray crystallography. Here we investigate both the interaction of beta-arrestin with GPCRs, and the beta-arrestin conformational changes in real time and in living human cells, using a series of fluorescence resonance energy transfer (FRET)-based beta-arrestin2 biosensors. We observe receptor-specific patterns of conformational changes in beta-arrestin2 that occur rapidly after the receptor-beta-arrestin2 interaction. After agonist removal, these changes persist for longer than the direct receptor interaction. Our data indicate a rapid, receptor-type-specific, two-step binding and activation process between GPCRs and beta-arrestins. They further indicate that beta-arrestins remain active after dissociation from receptors, allowing them to remain at the cell surface and presumably signal independently. Thus, GPCRs trigger a rapid, receptor-specific activation/deactivation cycle of beta-arrestins, which permits their active signalling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nuber, Susanne -- Zabel, Ulrike -- Lorenz, Kristina -- Nuber, Andreas -- Milligan, Graeme -- Tobin, Andrew B -- Lohse, Martin J -- Hoffmann, Carsten -- 1 R01 DA038882/DA/NIDA NIH HHS/ -- BB/K019864/1/Biotechnology and Biological Sciences Research Council/United Kingdom -- England -- Nature. 2016 Mar 31;531(7596):661-4. doi: 10.1038/nature17198. Epub 2016 Mar 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Pharmacology and Toxicology, University of Wurzburg, Versbacher Str. 9, 97078 Wurzburg, Germany. ; Rudolf Virchow Center, University of Wurzburg, Versbacher Str. 9, 97078 Wurzburg, Germany. ; Comprehensive Heart Failure Center, University of Wurzburg, Versbacher Str. 9, 97078 Wurzburg, Germany. ; Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK. ; MRC Toxicology Unit, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27007855" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arrestins/chemistry/*metabolism ; Biosensing Techniques ; Cattle ; Cell Line ; Cell Membrane/metabolism ; Cell Survival ; Crystallography, X-Ray ; Fluorescence Resonance Energy Transfer ; Humans ; Kinetics ; Models, Molecular ; Protein Binding ; Protein Conformation ; Receptors, G-Protein-Coupled/chemistry/*metabolism ; Signal Transduction ; Substrate Specificity ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2016-09-07
    Description: The study of human neurodegeneration has increasingly focused on a clinically diverse group of diseases that share the common pathologic feature of insoluble aggregates of α-synuclein (αSyn) in various populations of neurons and glia. Scientists have begun identifying factors that may initiate or accelerate αSyn aggregation and how this process...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2016-01-29
    Description: The protease HtrA2 has a protective role inside mitochondria, but promotes apoptosis under stress. We previously identified the G399S HtrA2 mutation in Parkinson's disease (PD) patients and reported mitochondrial dysfunction in vitro . Mitochondrial dysfunction is a common feature of PD and related to neurodegeneration. Complete loss of HtrA2 has been shown to cause neurodegeneration in mice. However, the full impact of HtrA2 overexpression or the G399S mutation is still to be determined in vivo . Here, we report the first HtrA2 G399S transgenic mouse model. Our data suggest that the mutation has a dominant-negative effect. We also describe a toxic effect of wild-type (WT) HtrA2 overexpression. Only low overexpression of the G399S mutation allowed viable animals and we suggest that the mutant protein is likely unstable. This is accompanied by reduced mitochondrial respiratory capacity and sensitivity to apoptotic cell death. Mice overexpressing WT HtrA2 were viable, yet these animals have inhibited mitochondrial respiration and significant induction of apoptosis in the brain leading to motor dysfunction, highlighting the opposing roles of HtrA2. Our data further underscore the importance of HtrA2 as a key mediator of mitochondrial function and its fine regulatory role in cell fate. The location and abundance of HtrA2 is tightly controlled and, therefore, human mutations leading to gain- or loss of function could provide significant risk for PD-related neurodegeneration.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2014-01-11
    Description: Lewy bodies and neurites are the pathological hallmark of Parkinson's disease. These structures are composed of fibrillized and ubiquitinated alpha-synuclein suggesting that impaired protein clearance is an important event in aggregate formation. The A30P mutation is known for its fast oligomerization, but slow fibrillization rate. Despite its toxicity to neurons, mechanisms involved in either clearance or conversion of A30P alpha-synuclein from its soluble state into insoluble fibrils and their effects in vivo are poorly understood. Synphilin-1 is present in Lewy bodies, interacting with alpha-synuclein in vivo and in vitro and promotes its sequestration into aggresomes, which are thought to act as cytoprotective agents facilitating protein degradation. We therefore crossed animals overexpressing A30P alpha-synuclein with synphilin-1 transgenic mice to analyze its impact on aggregation, protein clearance and phenotype progression. We observed that co-expression of synphilin-1 mildly delayed the motor phenotype caused by A30P alpha-synuclein. Additionally, the presence of N- and C-terminal truncated alpha-synuclein species and fibrils were strongly reduced in double-transgenic mice when compared with single-transgenic A30P mice. Insolubility of mutant A30P and formation of aggresomes was still detectable in aged double-transgenic mice, paralleled by an increase of ubiquitinated proteins and high autophagic activity. Hence, this study supports the notion that co-expression of synphilin-1 promotes formation of autophagic-susceptible aggresomes and consecutively the degradation of human A30P alpha-synuclein. Notably, although synphilin-1 overexpression significantly reduced formation of fibrils and astrogliosis in aged animals, a similar phenotype is present in single- and double-transgenic mice suggesting additional neurotoxic processes in disease progression.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2014-07-05
    Description: Lewy bodies, a pathological hallmark of Parkinson's disease (PD), contain aggregated alpha-synuclein (αSyn), which is found in several modified forms and can be discovered phosphorylated, ubiquitinated and truncated. Aggregation-prone truncated species of αSyn caused by aberrant cleavage of this fibrillogenic protein are hypothesized to participate in its sequestration into inclusions subsequently leading to synaptic dysfunction and neuronal death. Here, we investigated the role of calpain cleavage of αSyn in vivo by generating two opposing mouse models. We crossed into human [A30P]αSyn transgenic (i) mice deficient for calpastatin, a calpain-specific inhibitor, thus enhancing calpain activity (SynCAST(–)) and (ii) mice overexpressing human calpastatin leading to reduced calpain activity (SynCAST(+)). As anticipated, a reduced calpain activity led to a decreased number of αSyn-positive aggregates, whereas loss of calpastatin led to increased truncation of αSyn in SynCAST(–). Furthermore, overexpression of calpastatin decreased astrogliosis and the calpain-dependent degradation of synaptic proteins, potentially ameliorating the observed neuropathology in [A30P]αSyn and SynCAST(+) mice. Overall, our data further support a crucial role of calpains, particularly of calpain 1, in the pathogenesis of PD and in disease-associated aggregation of αSyn, indicating a therapeutic potential of calpain inhibition in PD.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...