共查询到20条相似文献,搜索用时 15 毫秒
1.
The semaphorin proteins were identified originally as axonal guidance factors functioning during neuronal development. In addition to this function, several semaphorins play diverse roles outside the nervous system. The class 4 semaphorin CD100/Sema4D, which utilizes plexin-B1 and CD72 as receptors, exerts important biological effects on a variety of cells, including the neuronal, epithelial and immune cells. Here, we review recent advances exploring the molecular mechanisms governing the biological functions of CD100/Sema4D.Received 1 July 2003; received after revision 25 July 2003; accepted 29 July 2003 相似文献
2.
CD100 is a leukocyte semaphorin 总被引:5,自引:0,他引:5
S. Delaire A. Elhabazi A. Bensussan L. Boumsell 《Cellular and molecular life sciences : CMLS》1998,54(11):1265-1276
CD100 was originally described as an activation molecule on the surface of human T lymphocytes. Its triggering through distinct
epitopes leads to different signals of costimulation with phorbol myristate acetate (PMA) or with CD3 and CD2. Interestingly,
CD100 was shown to associate with different partner molecules in T cells. First, CD100 can associate with CD45, a key molecule
with protein tyrosine phosphatase activity involved in T-cell transduction this association is physical and has functional
consequences for both partners. Second, CD100 interacts in its cytoplasmic domain with a Ser/Thr kinase for which it represents
a preferential substrate. Recently, CD100 was identified as a member of the semaphorin gene family. This family comprises
approximately 20 structurally related proteins. The first semaphorins were identified in the developing nervous system. Function
has been shown for only some of them and involves repulsion during growth cone guidance. Since CD100 was the first semaphorin
identified in the immune system, this raises the possibility of the involvement of members of the semaphorin family in other
physiological phenomena outside the nervous system.
Received 1 March 1998; received after revision 8 June 1998; accepted 8 June 1998 相似文献
3.
T. Hubert S. Grimal P. Carroll A. Fichard-Carroll 《Cellular and molecular life sciences : CMLS》2009,66(7):1223-1238
Collagens are extracellular proteins characterized by a structure in triple helices. There are 28 collagen types which differ
in size, structure and function. Their architectural and functional roles in connective tissues have been widely assessed.
In the nervous system, collagens are rare in the vicinity of the neuronal soma, occupying mostly a “marginal” position, such
as the meninges, the basement membranes and the sensory end organs. In neural development, however, where various ECM molecules
are known to be determinant, recent studies indicate that collagens are no exception, participating in axonal guidance, synaptogenesis
and Schwann cell differentiation. Insights on collagens function in the brain have also been derived from neural pathophysiological
conditions. This review summarizes the significant advances which underscore the function and importance of collagens in the
nervous system.
Received 09 September 2008; received after revision 24 October 2008; accepted 28 October 2008 相似文献
4.
Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels belong to the superfamily of voltage-gated pore loop channels. HCN channels are unique among
vertebrate voltage-gated ion channels, in that they have a reverse voltage-dependence that leads to activation upon hyperpolarization.
In addition, voltage-dependent opening of these channels is directly regulated by the binding of cAMP. HCN channels are encoded
by four genes (HCN1–4) and are widely expressed throughout the heart and the central nervous system. The current flowing through
HCN channels, designated Ih or If, plays a key role in the control of cardiac and neuronal rhythmicity (“pacemaker current”). In addition, Ih contributes to several other neuronal processes, including determination of resting membrane potential, dendritic integration
and synaptic transmission. In this review we give an overview on structure, function and regulation of HCN channels. Particular
emphasis will be laid on the complex roles of these channels for neuronal function and cardiac rhythmicity.
Received 22 August 2008; received after revision 22 September 2008; accepted 24 September 2008 相似文献
5.
6.
7.
Reticulons (RTNs) are membrane-spanning proteins sharing a typical domain named reticulon homology domain (RHD). RTN genes
have been identified in all eukaryotic organisms examined so far, and the corresponding proteins have been found predominantly
associated to the endoplasmic reticulum membranes. In animal and yeast, in which knowledge of the protein family is more advanced,
RTNs are involved in numerous cellular processes such as apoptosis, cell division and intracellular trafficking. Up to now,
a little attention has been paid to their plant counterparts, i.e., RTNLBs. In this review, we summarize the data available for RTNLB proteins and, using the data obtained with animal and
yeast models, several functions for RTNLBs in plant cells are proposed and discussed.
Received 01 July 2008; received after revision 08 September 2008; accepted 30 September 2008 相似文献
8.
S. Padilla U. C. Tran M. Jiménez-Hidalgo J. M. López-Martín A. Martín-Montalvo C. F. Clarke P. Navas C. Santos-Ocaña 《Cellular and molecular life sciences : CMLS》2009,66(1):173-186
Coenzyme Q is a lipid molecule required for respiration and antioxidant protection. Q biosynthesis in Saccharomyces cerevisiae requires nine proteins (Coq1p–Coq9p). We demonstrate in this study that Q levels are modulated during growth by its conversion
from demethoxy-Q (DMQ), a late intermediate. Similar conversion was produced when cells were subjected to oxidative stress
conditions. Changes in Q6/DMQ6 ratio were accompanied by changes in COQ7 gene mRNA levels encoding the protein responsible for the DMQ hydroxylation, the penultimate step in Q biosynthesis pathway.
Yeast coq null mutant failed to accumulate any Q late biosynthetic intermediate. However, in coq7 mutants the addition of exogenous Q produces the DMQ synthesis. Similar effect was produced by over-expressing ABC1/COQ8. These results support the existence of a biosynthetic complex that allows the DMQ6 accumulation and suggest that Coq7p is a control point for the Q biosynthesis regulation in yeast.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Received 04 September 2008; received after revision 22 October 2008; accepted 23 October 2008 相似文献
9.
Plexin transmembrane receptors and their semaphorin ligands, as well as their co-receptors (Neuropilin, Integrin, VEGFR2, ErbB2, and Met kinase) are emerging as key regulatory proteins in a wide variety of developmental, regenerative, but also pathological processes. The diverse arenas of plexin function are surveyed, including roles in the nervous, cardiovascular, bone and skeletal, and immune systems. Such different settings require considerable specificity among the plexin and semaphorin family members which in turn are accompanied by a variety of cell signaling networks. Underlying the latter are the mechanistic details of the interactions and catalytic events at the molecular level. Very recently, dramatic progress has been made in solving the structures of plexins and of their complexes with associated proteins. This molecular level information is now suggesting detailed mechanisms for the function of both the extracellular as well as the intracellular plexin regions. Specifically, several groups have solved structures for extracellular domains for plexin-A2, -B1, and -C1, many in complex with semaphorin ligands. On the intracellular side, the role of small Rho GTPases has been of particular interest. These directly associate with plexin and stimulate a GTPase activating (GAP) function in the plexin catalytic domain to downregulate Ras GTPases. Structures for the Rho GTPase binding domains have been presented for several plexins, some with Rnd1 bound. The entire intracellular domain structure of plexin-A1, -A3, and -B1 have also been solved alone and in complex with Rac1. However, key aspects of the interplay between GTPases and plexins remain far from clear. The structural information is helping the plexin field to focus on key questions at the protein structural, cellular, as well as organism level that collaboratoria of investigations are likely to answer. 相似文献
10.
Methionine adenosyltransferases (MATs) are the family of enzymes that synthesize the main biological methyl donor, S-adenosylmethionine. The high sequence conservation among catalytic subunits from bacteria and eukarya preserves key residues
that control activity and oligomerization, which is reflected in the protein structure. However, structural differences among
complexes with substrates and products have led to proposals of several reaction mechanisms. In parallel, folding studies
begin to explain how the three intertwined domains of the catalytic subunit are produced, and to highlight the importance
of certain intermediates in attaining the active final conformation. This review analyzes the available structural data and
proposes a consensus interpretation that facilitates an understanding of the pathological problems derived from impairment
of MAT function. In addition, new research opportunities directed toward clarification of aspects that remain obscure are
also identified.
Received 22 August 2008; received after revision 22 September 2008; accepted 26 September 2008 相似文献
11.
Cutaneous wound healing is a complex and highly coordinated process where a number of different cell types participate to
renew the damaged tissue under the strict regulation of soluble and insoluble factors. One of the most versatile processes
involved in wound repair is proteolysis. During cell migration, proteins of extracellular matrix are cleaved, often creating
biologically active cleavage products, and proteolysis of cellular contacts leads to increased cell motility and division.
Moreover, proteases activate various growth factors and other proteases in wound and regulate growth factor signaling by shedding
growth factor receptors on cell surface. Normally, proteolysis is strictly controlled, and changes in protease activity are
associated with alterations in wound closure and scar formation. Here, we present the current view on the role of metalloproteinases
and the plasmin-plasminogen system in normal and aberrant cutaneous wound repair and discuss their role as potential therapeutic
targets for chronic ulcers or fibrotic scars.
Received 07 July 2008; received after revision 11 August 2008; accepted 13 August 2008 相似文献
12.
F. Magherini A. Carpentieri A. Amoresano T. Gamberi C. De Filippo L. Rizzetto M. Biagini P. Pucci A. Modesti 《Cellular and molecular life sciences : CMLS》2009,66(5):933-947
In this study, a proteomic approach that combines selective labelling of proteins containing reduced cysteine residues with
two-dimensional electrophoresis/mass spectrometry was used to evaluate the redox state of protein cysteines during chronological
ageing in Saccharomyces cerevisiae. The procedure was developed on the grounds that biotinconjugated iodoacetamide (BIAM) specifically reacts with reduced cysteine
residues. BIAM-labelled proteins can then be selectively isolated by streptavidin affinity capture. We compared cells grown
on 2% glucose in the exponential phase and during chronological ageing and we found that many proteins undergo cysteine oxidation.
The target proteins include enzymes involved in glucose metabolism. Both caloric restriction and growth on glycerol resulted
in a decrease in the oxidative modification. Furthermore, in these conditions a reduced production of ROS and a more negative
glutathione half cell redox potential were observed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Received 15 September 2008; received after revision 17 December 2008; accepted 06 January 2009 相似文献
13.
14.
15.
Two major functions of the Golgi apparatus (GA) are formation of complex glycans and sorting of proteins destined for various
subcellular compartments or secretion. To fulfill these tasks proper localization of the accessory proteins within the different
sub-compartments of the GA is crucial. Here we investigate structural determinants mediating transition of the two glycosyltransferases
β-1,4- galactosyltransferase 1 (gal-T1) and the α-1,3-fucosyltransferase 6 (fuc-T6) from the trans-Golgi cisterna to the trans-Golgi network (TGN). Upon treatment with the ionophore monensin both glycosyltransferases are found in TGN-derived swollen
vesicles, as determined by confocal fluorescence microscopy and density gradient fractionation. Both enzymes carry a signal
consisting of the amino acids E5P6 in gal-T1 and D2P3 in fuc-T6 necessary for the transition of these glycosyltransferases from the trans-Golgi cisterna to the TGN, but not for their steady state localization in the trans-Golgi cisterna.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Received 30 July 2008; received after revision 17 September 2008; accepted 29 September 2008 相似文献
16.
Arachiche A Badirou I Dachary-Prigent J Garcin I Geldwerth-Feniger D Kerbiriou-Nabias D 《Cellular and molecular life sciences : CMLS》2008,65(23):3861-3871
Rapid Ca2+-dependent phospholipid (PL) reorganization (scrambling) at the plasma membrane is a mechanism common to hematopoietic cells
exposing procoagulant phosphatidylserine (PS). The aim of this research was to determine whether activation of the extracellular
signal-regulated kinase (ERK) pathway was required for PL scrambling, based on a single report analyzing both responses induced
by Ca2+ ionophores in megakaryoblastic HEL cells. Ca2+ ionophore-stimulated ERK phosphorylation was induced in platelets without external Ca2+, whereas exogenous Ca2+ entry was crucial for ERK activation in Jurkat T cells. In both cells, membrane scrambling only occurred following Ca2+ entry and was not blocked by inhibiting ERK phosphorylation. Furthermore, ERK proteins are strongly phosphorylated in transformed
B lymphoblastic cell lines, which do not expose PS in their resting state. Overall, the data demonstrated that ERK activation
and membrane scrambling are independent mechanisms.
A. Arachiche, I. Badirou: These authors contributed equally to this work.
Received 18 June 2008; received after revision 24 September 2008; accepted 1 October 2008 相似文献
17.
Pili in Gram-negative and Gram-positive bacteria — structure, assembly and their role in disease 总被引:2,自引:0,他引:2
Many bacterial species possess long filamentous structures known as pili or fimbriae extending from their surfaces. Despite
the diversity in pilus structure and biogenesis, pili in Gram-negative bacteria are typically formed by non-covalent homopolymerization
of major pilus subunit proteins (pilins), which generates the pilus shaft. Additional pilins may be added to the fiber and
often function as host cell adhesins. Some pili are also involved in biofilm formation, phage transduction, DNA uptake and
a special form of bacterial cell movement, known as ‘twitching motility’ In contrast, the more recently discovered pili in
Gram-positive bacteria are formed by covalent polymerization of pilin subunits in a process that requires a dedicated sortase
enzyme. Minor pilins are added to the fiber and play a major role in host cell colonization.
This review gives an overview of the structure, assembly and function of the best-characterized pili of both Gram-negative
and Gram-positive bacteria.
Received 08 August 2008; received after revision 24 September 2008; accepted 01 October 2008 相似文献
18.
Galat A 《Cellular and molecular life sciences : CMLS》2008,65(21):3481-3493
Extracellular domains of some cellular receptors expressed in the organisms at different levels of development belong to three-fingered
protein (TFP) fold. The Homo sapiens genome encodes at least 45 genes containing from one to three TFP domains (TFPDs), namely diverse paralogues of the Ly6 gene,
CD59 and the receptors of activins, bone morphogenetic proteins, Mullerian inhibiting substance and transforming growth factor-β.
C4.4a and urokinase/plasminogen activatory receptor contain two and three TFPD repeats, respectively. These diverse proteins
have a low overall sequence similarity with each other and their hydrophobicity levels vary to a considerable degree. It is
suggested that sequence differentiation within the TFPD led to distinct groups of proteins whose attributes were optimized
to fit both the physicochemical properties specific to their functional microenvironment and selective targeting of their
highly diversified extracellular cofactors.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Received 7 August 2008; accepted 29 August 2008 相似文献
19.
Katona RL Sinkó I Holló G Szucs KS Praznovszky T Kereso J Csonka E Fodor K Cserpán I Szakál B Blazsó P Udvardy A Hadlaczky G 《Cellular and molecular life sciences : CMLS》2008,65(23):3830-3838
Mammalian artificial chromosomes (MACs) are safe, stable, non-integrating genetic vectors with almost unlimited therapeutic
transgene-carrying capacity. The combination of MAC and stem cell technologies offers a new strategy for stem cell-based therapy,
the efficacy of which was confirmed and validated by using a mouse model of a devastating monogenic disease, galactocerebrosidase
deficiency (Krabbe’s disease). Therapeutic MACs were generated by sequence-specific loading of galactocerebrosidase transgenes
into a platform MAC, and stable, pluripotent mouse embryonic stem cell lines were established with these chromosomes. The
transgenic stem cells were thoroughly characterized and used to produce chimeric mice on the mutant genetic background. The
lifespan of these chimeras was increased twofold, verifying the feasibility of the development of MAC-stem cell systems for
the delivery of therapeutic genes in stem cells to treat genetic diseases and cancers, and to produce cell types for cell
replacement therapies.
Received 29 July 2008; received after revision 22 September 2008; accepted 24 September 2008 相似文献
20.
The bugs that came in from the cold: molecular adaptations to low temperatures in insects 总被引:2,自引:0,他引:2
The widespread distribution of insects over many ecological niches is a testimony to their evolutionary success. The colonization
of environments at high latitudes or altitudes required the evolution of biochemical strategies that reduced the impact of
cold or freezing stress. This review focuses on our current interests in some of the genes and proteins involved in low temperature
survival in insects. Although the most widespread form of protection is the synthesis of low molecular weight polyol cryoprotectants,
proteins with intrinsic protective properties, such as the thermal hysteresis or antifreeze proteins are also important. These
have been cloned and characterized in certain moths and beetles. Molecular techniques allowing the isolation of genes differentially
regulated by low temperatures have revealed that heat shock proteins, cold stress proteins, membrane protectants, as well
as ice nucleators and other less well characterized proteins likely also play a role in cold hardiness.
Received 10 June 2008; received after revision 17 November 2008; accepted 18 November 2008 相似文献