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1.
Molecular and structural effects of inverse agonistic mutations on signaling of the thyrotropin receptor – a basally active GPCR 总被引:1,自引:0,他引:1
Kleinau G Jaeschke H Mueller S Worth CL Paschke R Krause G 《Cellular and molecular life sciences : CMLS》2008,65(22):3664-3676
Several mutations that decrease the basal signaling activity of G-protein coupled receptors (GPCRs) with pathogenic implications
are known. Here we study the molecular mechanisms responsible for this phenotype and investigate how basal and further activated
receptor conformations are interrelated. In the basally active thyroid stimulating hormone receptor (TSHR) we combined spatially-distant
mutations with opposing effects on basal activity in double-mutations and characterized mutant basal and TSH induced signaling.
Mutations lowering basal activity always have a suppressive influence on TSH induced signaling and on constitutively activating
mutations (CAMs). Our results suggest that the conformation of a basally ‘silenced’ GPCR might impair its intrinsic capacity
for signaling compared to the wild-type. Striking differences in conformation and intramolecular interactions between TSHR
models built using the crystal structures of inactive rhodopsin and partially active opsin help illuminate the molecular details
underlying mutations decreasing basal activity.
G. Kleinau, H. Jaeschke: These two authors contributed equally to this work.
Received 31 July 2008; received after revision 12 September 2008; accepted 19 September 2008 相似文献
2.
Ouria Dkhissi-Benyahya Christine Coutanson Kenneth Knoblauch Hasna Lahouaoui Vincent Leviel Catherine Rey Mohamed Bennis Howard M. Cooper 《Cellular and molecular life sciences : CMLS》2013,70(18):3435-3447
The retinal circadian clock is crucial for optimal regulation of retinal physiology and function, yet its cellular location in mammals is still controversial. We used laser microdissection to investigate the circadian profiles and phase relations of clock gene expression and Period gene induction by light in the isolated outer (rods/cones) and inner (inner nuclear and ganglion cell layers) regions in wild-type and melanopsin-knockout (Opn 4 ?/? ) mouse retinas. In the wild-type mouse, all clock genes are rhythmically expressed in the photoreceptor layer but not in the inner retina. For clock genes that are rhythmic in both retinal compartments, the circadian profiles are out of phase. These results are consistent with the view that photoreceptors are a potential site of circadian rhythm generation. In mice lacking melanopsin, we found an unexpected loss of clock gene rhythms and of the photic induction of Per1-Per2 mRNAs only in the outer retina. Since melanopsin ganglion cells are known to provide a feed-back signalling pathway for photic information to dopaminergic cells, we further examined dopamine (DA) synthesis in Opn 4 ?/? mice. The lack of melanopsin prevented the light-dependent increase of tyrosine hydroxylase (TH) mRNA and of DA and, in constant darkness, led to comparatively high levels of both components. These results suggest that melanopsin is required for molecular clock function and DA regulation in the retina, and that Period gene induction by light is mediated by a melanopsin-dependent, DA-driven signal acting on retinal photoreceptors. 相似文献
3.
Magnus Kjaergaard 《Cellular and molecular life sciences : CMLS》2017,74(17):3205-3224
Intrinsic disorder is common in integral membrane proteins, particularly in the intracellular domains. Despite this observation, these domains are not always recognized as being disordered. In this review, we will discuss the biological functions of intrinsically disordered regions of membrane proteins, and address why the flexibility afforded by disorder is mechanistically important. Intrinsically disordered regions are present in many common classes of membrane proteins including ion channels and transporters; G-protein coupled receptors (GPCRs), receptor tyrosine kinases and cytokine receptors. The functions of the disordered regions are many and varied. We will discuss selected examples including: (1) Organization of receptors, kinases, phosphatases and second messenger sources into signaling complexes. (2) Modulation of the membrane-embedded domain function by ball-and-chain like mechanisms. (3) Trafficking of membrane proteins. (4) Transient membrane associations. (5) Post-translational modifications most notably phosphorylation and (6) disorder-linked isoform dependent function. We finish the review by discussing the future challenges facing the membrane protein community regarding protein disorder. 相似文献
4.
Davies WI Zheng L Hughes S Tamai TK Turton M Halford S Foster RG Whitmore D Hankins MW 《Cellular and molecular life sciences : CMLS》2011,68(24):4115-4132
Melanopsin (OPN4) is an opsin photopigment that, in mammals, confers photosensitivity to retinal ganglion cells and regulates
circadian entrainment and pupil constriction. In non-mammalian species, two forms of opn4 exist, and are classified into mammalian-like (m) and non-mammalian-like (x) clades. However, far less is understood of the function of this photopigment family. Here we identify in zebrafish five
melanopsins (opn4m-1, opn4m-2, opn4m-3, opn4x-1 and opn4x-2), each encoding a full-length opsin G protein. All five genes are expressed in the adult retina in a largely non-overlapping
pattern, as revealed by RNA in situ hybridisation and immunocytochemistry, with at least one melanopsin form present in all
neuronal cell types, including cone photoreceptors. This raises the possibility that the teleost retina is globally light
sensitive. Electrophysiological and spectrophotometric studies demonstrate that all five zebrafish melanopsins encode a functional
photopigment with peak spectral sensitivities that range from 470 to 484 nm, with opn4m-1 and opn4m-3 displaying invertebrate-like
bistability, where the retinal chromophore interchanges between cis- and trans-isomers in a light-dependent manner and remains within the opsin binding pocket. In contrast, opn4m-2, opn4x-1 and opn4x-2
are monostable and function more like classical vertebrate-like photopigments, where the chromophore is converted from 11-cis to all-trans retinal upon absorption of a photon, hydrolysed and exits from the binding pocket of the opsin. It is thought that all melanopsins
exhibit an invertebrate-like bistability biochemistry. Our novel findings, however, reveal the presence of both invertebrate-like
and vertebrate-like forms of melanopsin in the teleost retina, and indicate that photopigment bistability is not a universal
property of the melanopsin family. The functional diversity of these teleost melanopsins, together with their widespread expression
pattern within the retina, suggests that melanopsins confer global photosensitivity to the teleost retina and might allow
for direct “fine-tuning” of retinal circuitry and physiology in the dynamic light environments found in aquatic habitats. 相似文献
5.
Despite the absence of classical tyrosine kinases encrypted in the kinome of Plasmodium falciparum, biochemical analyses have detected significant tyrosine phosphorylation in its cell lysates. Supporting such phosphorylation
is critical for parasite development. These observations have thus raised queries regarding the plasmodial enzymes accountable
for tyrosine kinase activities in vivo. In the current investigation, immunoblot analysis intriguingly demonstrated that Pfnek3,
a plasmodial mitogen-activated protein kinase kinase (MAPKK), displayed both serine/threonine and tyrosine kinase activities
in autophosphorylation reactions as well as in phosphorylation of the exogenous myelin basic protein substrate. The results
obtained strongly support Pfnek3 as a novel dual-specificity kinase of the malarial parasite, even though it displays a HGDLKSTN
motif in the catalytic loop that resembles the consensus HRDLKxxN signature found in the serine/threonine kinases. Notably,
its serine/threonine and tyrosine kinase activities were found to be distinctly influenced by Mg2+ and Mn2+ cofactors. Further probing into the regulatory mechanism of Pfnek3 also revealed tyrosine phosphorylation to be a crucial
factor that stimulates its kinase activity. Through biocomputational analyses and functional assays, tyrosine residues Y117,
Y122, Y172, and Y238 were proposed as phosphorylation sites essential for mediating the catalytic activities of Pfnek3. The
discovery of Pfnek3’s dual role in phosphorylation marks its importance in closing the loop for cellular regulation in P. falciparum, which remains elusive to date. 相似文献
6.
In the early 1990s, the search for protein kinases led to the discovery of a novel family of non-receptor tyrosine kinases,
the Janus kinases or JAKs. These proteins were unusual because they contained two kinase homology domains and no other known
signaling modules. It soon became clear that these were not ‘just another’ type of kinase. Their ability to complement mutant
cells insensitive to interferons and to be activated by a variety of cytokines demonstrated their central signaling function.
Now, as we approach the end of the decade, it is evident from biochemical studies to knockout mice that JAKs play non-redundant
functions in development, differentiation, and host defense mechanisms. Here, recent progress is reviewed, with particular
emphasis on structure-function studies aimed at revealing how this family of tyrosine kinases is regulated. 相似文献
7.
Ling Zhang Rolf Postina Yingqun Wang 《Cellular and molecular life sciences : CMLS》2009,66(24):3923-3935
Receptor for advanced glycation end products (RAGE) mediates diverse physiological and pathological effects and is involved
in the pathogenesis of Alzheimer’s disease (AD). RAGE is a receptor for amyloid β peptides (Aβ), mediates Aβ neurotoxicity
and also promotes Aβ influx into the brain and contributes to Aβ aggregation. Soluble RAGE (sRAGE), a secreted RAGE isoform,
acts as a decoy receptor to antagonize RAGE-mediated damages. Accumulating evidence has suggested that sRAGE represents a
promising pharmaceutic against RAGE-mediated disorders. Recent studies revealed proteolysis of RAGE as a previously unappreciated
means of sRAGE production. In this review we summarize these findings on the proteolytic cleavage of RAGE and discuss the
underlying regulatory mechanisms of RAGE shedding. Furthermore, we propose a model in which proteolysis of RAGE could restrain
AD development by reducing Aβ transport into the brain and Aβ production via BACE. Thus, the modulation of RAGE proteolysis
provides a novel intervention strategy for AD. 相似文献
8.
Leonard Girnita Claire Worrall Shin-Ichiro Takahashi Stefan Seregard Ada Girnita 《Cellular and molecular life sciences : CMLS》2014,71(13):2403-2427
The insulin-like growth factor type 1 receptor (IGF-1R) plays a key role in the development and progression of cancer; however, therapeutics targeting it have had disappointing results in the clinic. As a receptor tyrosine kinase (RTK), IGF-1R is traditionally described as an ON/OFF system, with ligand stabilizing the ON state and exclusive kinase-dependent signaling activation. Newly added to the traditional model, ubiquitin-mediated receptor downregulation and degradation was originally described as a response to ligand/receptor interaction and thus inseparable from kinase signaling activation. Yet, the classical model has proven over-simplified and insufficient to explain experimental evidence accumulated over the last decade, including kinase-independent signaling, unbalanced signaling, or dissociation between signaling and receptor downregulation. Based on the recent findings that IGF-1R “borrows” components of G-protein coupled receptor (GPCR) signaling, including β-arrestins and G-protein-related kinases, we discuss the emerging paradigm for the IGF-1R as a functional RTK/GPCR hybrid, which integrates the kinase signaling with the IGF-1R canonical GPCR characteristics. The contradictions to the classical IGF-1R signaling concept as well as the design of anti-IGF-1R therapeutics treatment are considered in the light of this paradigm shift and we advocate recognition of IGF-1R as a valid target for cancer treatment. 相似文献
9.
Multiple cellular functions of urokinase and its receptor are associated with the receptor’s capability to interact with a
number of ligands at the molecular level. The presence of urokinase is generally needed for the urokinase receptor to acquire
this capability. Recent X-ray studies of the structure of the urokinase receptor in complex with either its ligand or peptide
inhibitors demonstrate the flexibility of the domain organization of the receptor, suggesting that unliganded urokinase receptor
may exist in a latent form that has a conformation different from its ligand-binding form.
Received 22 November 2006; received after revision 8 January 2007; accepted 7 February 2007 相似文献
10.
11.
The Wnt/β-catenin signaling pathway plays important roles in embryonic development and tissue homeostasis, and is implicated
in human disease. Wnts transduce signals via transmembrane receptors of the Frizzled (Fzd/Fz) family and the low density lipoprotein
receptor-related protein 5/6 (Lrp5/6). A key mechanism in their signal transduction is that Wnts induce Lrp6 signalosomes,
which become phosphorylated at multiple conserved sites, notably at PPSPXS motifs. Lrp6 phosphorylation is crucial to β-catenin
stabilization and pathway activation by promoting Axin and Gsk3 recruitment to phosphorylated sites. Here, we summarize how
proline-directed kinases (Gsk3, PKA, Pftk1, Grk5/6) and non-proline-directed kinases (CK1 family) act upon Lrp6, how the phosphorylation
is regulated by ligand binding and mitosis, and how Lrp6 phosphorylation leads to β-catenin stabilization. 相似文献
12.
Tyler S. Smith Benjamin Spitzbarth Jian Li Donald R. Dugger Gabi Stern-Schneider Elisabeth Sehn Susan N. Bolch J. Hugh McDowell Jeremiah Tipton Uwe Wolfrum W. Clay Smith 《Cellular and molecular life sciences : CMLS》2013,70(23):4603-4616
Arrestins are dynamic proteins that move between cell compartments triggered by stimulation of G-protein-coupled receptors. Even more dynamically in vertebrate photoreceptors, arrestin1 (Arr1) moves between the inner and outer segments according to the light conditions. Previous studies have shown that the light-driven translocation of Arr1 in rod photoreceptors is initiated by rhodopsin through a phospholipase C/protein kinase C (PKC) signaling cascade. The purpose of this study is to identify the PKC substrate that regulates the translocation of Arr1. Mass spectrometry was used to identify the primary phosphorylated proteins in extracts prepared from PKC-stimulated mouse eye cups, confirming the finding with in vitro phosphorylation assays. Our results show that Bardet–Biedl syndrome 5 (BBS5) is the principal protein phosphorylated either by phorbol ester stimulation or by light stimulation of PKC. Via immunoprecipitation of BBS5 in rod outer segments, Arr1 was pulled down; phosphorylation of BBS5 reduced this co-precipitation of Arr1. Immunofluorescence and immunoelectron microscopy showed that BBS5 principally localizes along the axonemes of rods and cones, but also in photoreceptor inner segments, and synaptic regions. Our principal findings in this study are threefold. First, we demonstrate that BBS5 is post-translationally regulated by phosphorylation via PKC, an event that is triggered by light in photoreceptor cells. Second, we find a direct interaction between BBS5 and Arr1, an interaction that is modulated by phosphorylation of BBS5. Finally, we show that BBS5 is distributed along the photoreceptor axoneme, co-localizing with Arr1 in the dark. These findings suggest a role for BBS5 in regulating light-dependent translocation of Arr1 and a model describing its role in Arr1 translocation is proposed. 相似文献
13.
Glucagon-like peptide-1(1-37) inhibits chemokine-induced migration of human CD4-positive lymphocytes
Nikolaus Marx Mathias Burgmaier Philipp Heinz Mirjam Ostertag Angelina Hausauer Helga Bach Renate Durst Vinzenz Hombach Daniel Walcher 《Cellular and molecular life sciences : CMLS》2010,67(20):3549-3555
The present study examined the effect of GLP-1(1-37) on chemokine-induced CD4-positive lymphocyte migration as an early and
critical step in atherogenesis. Pretreatment with GLP-1(1-37) reduced the SDF-induced migration of isolated human CD4-positive
lymphocytes in a concentration-dependent manner. Similar effects were seen when RANTES was used as a chemokine. GLP-1(1-37)’s
effect on CD4-positive lymphocyte migration was mediated through an early inhibition of chemokine-induced PI-3 kinase activity.
Downstream, GLP-1(1-37) inhibited SDF-induced phosphorylation of MLC and cofilin and limited f-actin formation as well as
ICAM3 translocation. Furthermore, exendin-4 inhibited SDF-induced migration of CD4-positive lymphocytes similarly to GLP-1(1-37),
and transfection of these cells with GLP-1 receptor siRNA abolished GLP-1(1-37)’s action on chemokine-induced ICAM3 translocation,
suggesting an effect mediated via the GLP-1 receptor. Thus, GLP-1(1-37) inhibits chemokine-induced CD4-positive lymphocyte
migration by inhibition of the PI3-kinase pathway and via the GLP-1 receptor. This effect provides a potential novel mechanism
for how GLP-1(1-37) may modulate vascular disease. 相似文献
14.
Reddy SV 《Cellular and molecular life sciences : CMLS》2006,63(4):391-398
Paget’s disease of bone is a chronic focal skeletal disorder characterized by increased bone resorption by the osteoclasts.
Paramyxoviral gene products have been detected in pagetic osteoclasts. Paget’s disease is an autosomal dominant trait with
genetic heterogeneity. Several mutations in the ubiquitin-associated (UBA) domain of sequestosome 1 (SQSTM1/p62) have been
identified in patients with Paget’s disease. Similarly, mutations in the valosin-containing protein (VCP) gene have been shown
to cause inclusion body myopathy associated with Paget’s disease of bone and frontotemporal dementia. In addition, gene polymorphisms
and enhanced levels of cytokine/growth factors associated with Paget’s disease have been identified. However, the etiologic
factors in Paget’s disease remain elusive. A cause and effect relationship for the paramyxoviral infection and SQSTM1/ p62
gene mutations responsible for pagetic osteoclast development and disease severity are unclear. This article will highlight
the etiologic factors involved in the pathogenesis of Paget’s disease.
Received 6 October 2005; received after revision 2 November 2005; accepted 24 November 2005 相似文献
15.
Chromosome integrity in response to chemically or radiation-induced chromosome breaks and the perturbation of ongoing replication
forks relies on multiple DNA repair mechanisms. However, repair of these lesions may lead to unwanted chromosome rearrangement
if not properly executed or regulated. As these types of chromosomal alterations threaten the cell’s and the organism’s very
own survival, multiple systems are developed to avoid or at least limit break-induced chromosomal rearrangements. In this
review, we highlight cellular strategies for repressing DNA break-induced chromosomal translocations in multiple model systems
including yeast, mouse, and human. These pathways select proper homologous templates or broken DNA ends for the faithful repair
of DNA breaks to avoid undesirable chromosomal translocations. 相似文献
16.
Jessica Rodgers Stuart N. Peirson Steven Hughes Mark W. Hankins 《Cellular and molecular life sciences : CMLS》2018,75(19):3609-3624
Melanopsin is a blue light-sensitive opsin photopigment involved in a range of non-image forming behaviours, including circadian photoentrainment and the pupil light response. Many naturally occurring genetic variants exist within the human melanopsin gene (OPN4), yet it remains unclear how these variants affect melanopsin protein function and downstream physiological responses to light. Here, we have used bioinformatic analysis and in vitro expression systems to determine the functional phenotypes of missense human OPN4 variants. From 1242 human OPN4 variants collated in the NCBI Short Genetic Variation database (dbSNP), we identified 96 that lead to non-synonymous amino acid substitutions. These 96 missense mutations were screened using sequence alignment and comparative approaches to select 16 potentially deleterious variants for functional characterisation using calcium imaging of melanopsin-driven light responses in HEK293T cells. We identify several previously uncharacterised OPN4 mutations with altered functional properties, including attenuated or abolished light responses, as well as variants demonstrating abnormal response kinetics. These data provide valuable insight into the structure–function relationships of human melanopsin, including several key functional residues of the melanopsin protein. The identification of melanopsin variants with significantly altered function may serve to detect individuals with disrupted melanopsin-based light perception, and potentially highlight those at increased risk of sleep disturbance, circadian dysfunction, and visual abnormalities. 相似文献
17.
18.
Steffen Ducheyne 《Archive for History of Exact Sciences》2011,65(2):181-227
This article seeks to provide a historically well-informed analysis of an important post-Newtonian area of research in experimental
physics between 1798 and 1898, namely the determination of the mean density of the earth and, by the end of the nineteenth
century, the gravitational constant. Traditionally, research on these matters is seen as a case of “puzzle solving.” In this
article, the author shows that such focus does not do justice to the evidential significance of eighteenth- and nineteenth-century
experimental research on the mean density of the earth and the gravitational constant. As Newton’s theory of universal gravitation
was mainly based on astronomical observation, it remained to be shown that Newton’s law of universal gravitation did not break
down at terrestrial distances. In this context, Cavendish’ experiment and related nineteenth-century experiments played a
decisive role, for they provided converging and increasingly stronger evidence for the universality of Newton’s theory of
gravitation. More precisely, the author shall argue that, as the accuracy and precision of the experimental apparatuses and
the procedures to eliminate external disturbances involved increasingly improved, the empirical support for the universality
of Newton’s theory of gravitation improved correspondingly. 相似文献
19.
Iness Charfi Karim Nagi Ouissame Mnie-Filali Dominic Thibault Gianfranco Balboni Peter W. Schiller Louis-Eric Trudeau Graciela Pineyro 《Cellular and molecular life sciences : CMLS》2014,71(8):1529-1546
Signaling bias refers to G protein-coupled receptor ligand ability to preferentially activate one type of signal over another. Bias to evoke signaling as opposed to sequestration has been proposed as a predictor of opioid ligand potential for generating tolerance. Here we measured whether delta opioid receptor agonists preferentially inhibited cyclase activity over internalization in HEK cells. Efficacy (τ) and affinity (KA) values were estimated from functional data and bias was calculated from efficiency coefficients (log τ/KA). This approach better represented the data as compared to alternative methods that estimate bias exclusively from τ values. Log (τ/KA) coefficients indicated that SNC-80 and UFP-512 promoted cyclase inhibition more efficiently than DOR internalization as compared to DPDPE (bias factor for SNC-80: 50 and for UFP-512: 132). Molecular determinants of internalization were different in HEK293 cells and neurons with βarrs contributing to internalization in both cell types, while PKC and GRK2 activities were only involved in neurons. Rank orders of ligand ability to engage different internalization mechanisms in neurons were compared to rank order of E max values for cyclase assays in HEK cells. Comparison revealed a significant reversal in rank order for cyclase E max values and βarr-dependent internalization in neurons, indicating that these responses were ligand-specific. Despite this evidence, and because kinases involved in internalization were not the same across cellular backgrounds, it is not possible to assert if the magnitude and nature of bias revealed by rank orders of maximal responses is the same as the one measured in HEK cells. 相似文献
20.
Identification of tyrosine-phosphorylated proteins of the mitochondrial oxidative phosphorylation machinery 总被引:1,自引:1,他引:0
Augereau O Claverol S Boudes N Basurko MJ Bonneu M Rossignol R Mazat JP Letellier T Dachary-Prigent J 《Cellular and molecular life sciences : CMLS》2005,62(13):1478-1488
The role of some serine/threonine kinases in the regulation of mitochondrial physiology is now well established, but little is known about mitochondrial tyrosine kinases. We showed that tyrosine phosphorylation of rat brain mitochondrial proteins was increased by in vitro addition of ATP and H2O2, and also during in situ ATP production at state 3, and maximal reactive oxygen species production. The Src kinase inhibitor PP2 decreased tyrosine phosphorylation and respiratory rates at state 3. We found that the 39-kDa subunit of complex I was tyrosine phosphorylated, and we identified putative tyrosine-phosphorylated subunits for the other complexes. We also have strong evidence that the FoF1-ATP synthase α chain is probably tyrosine-phosphorylated, but demonstrated that the β chain is not. The tyrosine phosphatase PTP 1B was found in brain but not in muscle, heart or liver mitochondria. Our results suggest that tyrosine kinases and phosphatases are involved in the regulation of oxidative phosphorylation.Received 7 January 2005; received after revision 19 April 2005; accepted 22 April 2005 相似文献