Probing the S100 protein family through genomic and functional analysis (original) (raw)
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Functional roles of S100 proteins, calcium-binding proteins of the EF-hand type
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1999
A multigenic family of Ca 2 -binding proteins of the EF-hand type known as S100 comprises 19 members that are differentially expressed in a large number of cell types. Members of this protein family have been implicated in the Ca 2dependent (and, in some cases, Zn 2 -or Cu 2 -dependent) regulation of a variety of intracellular activities such as protein phosphorylation, enzyme activities, cell proliferation (including neoplastic transformation) and differentiation, the dynamics of cytoskeleton constituents, the structural organization of membranes, intracellular Ca 2 homeostasis, inflammation, and in protection from oxidative cell damage. Some S100 members are released or secreted into the extracellular space and exert trophic or toxic effects depending on their concentration, act as chemoattractants for leukocytes, modulate cell proliferation, or regulate macrophage activation. Structural data suggest that many S100 members exist within cells as dimers in which the two monomers are related by a two-fold axis of rotation and that Ca 2 binding induces in individual monomers the exposure of a binding surface with which S100 dimers are believed to interact with their target proteins. Thus, any S100 dimer is suggested to expose two binding surfaces on opposite sides, which renders homodimeric S100 proteins ideal for crossbridging two homologous or heterologous target proteins. Although in some cases different S100 proteins share their target proteins, in most cases a high degree of target specificity has been described, suggesting that individual S100 members might be implicated in the regulation of specific activities. On the other hand, the relatively large number of target proteins identified for a single S100 protein might depend on the specific role played by the individual regions that in an S100 molecule contribute to the formation of the binding surface. The pleiotropic roles played by S100 members, the identification of S100 target proteins, the analysis of functional correlates of S100-target protein interactions, and the elucidation of the threedimensional structure of some S100 members have greatly increased the interest in S100 proteins and our knowledge of S100 protein biology in the last few years. S100 proteins probably are an example of calcium-modulated, regulatory proteins that intervene in the fine tuning of a relatively large number of specific intracellular and (in the case of some members) extracellular activities. Systems, including knock-out animal models, should be now used with the aim of defining the correspondence between the in vitro regulatory role(s) attributed to individual members of this protein family and the in vivo function(s) of each S100 protein. ß 0167-4889 / 99 / $^see front matter ß 1999 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 -4 8 8 9 ( 9 9 ) 0 0 0 5 8 -0 * Pro¢laggrin Keratins [24,26] Regulates lateral association of keratin intermediate ¢laments [24,26] Trychohyalin Keratins [25] Regulates lateral association of keratin intermediate ¢laments [25] Repetin Keratins [27] Regulates lateral association of keratin intermediate ¢laments [27]
The International Journal of Biochemistry & Cell Biology, 2001
S100 is a multigenic family of non-ubiquitous Ca 2 + -modulated proteins of the EF-hand type expressed in vertebrates exclusively and implicated in intracellular and extracellular regulatory activities. Within cells, most of S100 members exist in the form of antiparallely packed homodimers (in some cases heterodimers), capable of functionally crossbridging two homologous or heterologous target proteins in a Ca 2 + -dependent (and, in some instances, Ca 2 + -independent) manner. S100 oligomers can also form, under the non-reducing conditions found in the extracellular space and/or within cells upon changes in the cell redox status. Within cells, S100 proteins have been implicated in the regulation of protein phosphorylation, some enzyme activities, the dynamics of cytoskeleton components, transcription factors, Ca 2 + homeostasis, and cell proliferation and differentiation. Certain S100 members are released into the extracellular space by an unknown mechanism. Extracellular S100 proteins stimulate neuronal survival and/or differentiation and astrocyte proliferation, cause neuronal death via apoptosis, and stimulate (in some cases) or inhibit (in other cases) the activity of inflammatory cells. A cell surface receptor, RAGE, has been identified on inflammatory cells and neurons for S100A12 and S100B, which transduces S100A12 and S100B effects. It is not known whether RAGE is a universal S100 receptor, S100 members interact with other cell surface receptors, or S100 protein interaction with other extracellular factors specifies the biological effects of a given S100 protein on a target cell. The variety of intracellular target proteins of S100 proteins and, in some cases, of a single S100 protein, and the cell specificity of expression of certain S100 members suggest that these proteins might have a role in the fine regulation of effector proteins and/or specific steps of signaling pathways/cellular functions. Future analyses should discriminate between functionally relevant S100 interactions with target proteins and in vitro observations devoid of physiological importance.
Phagocyte-specific S100 proteins: a novel group of proinflammatory molecules
Trends in Immunology, 2003
Three members of the S100 family of calcium-binding proteins comprise a new group of proinflammatory molecules released by phagocytes. A novel inflammatory syndrome defined by extraordinarily high expression of S100A8 and S100A9 confirmed recent observations in vitro demonstrating a role of these proteins during recruitment of leukocytes. S100A12 directly activates endothelial cells, mononuclear phagocytes and lymphocytes through interaction with the receptor for advanced glycation end products. Thus, these S100-proteins are attractive targets to modulate inflammation. Even although the S100 protein family is the largest group of calcium-binding proteins, the main function of these molecules has not been finally defined [1]. Members of this family are characterized by a relatively low molecular weight and the presence of two calcium-binding sites of the EF-hand type (helix-loop-helix calcium-binding domains). Their tissue-specific expression pattern is of particular interest. Recent work points to prominent proinflammatory functions performed by at least three members of this protein family, S100A8, S100A9 and S100A12, which are mainly expressed by phagocytes.
S100B protein in tissue development, repair and regeneration
World Journal of Biological Chemistry, 2013
The Ca 2+ -binding protein of the EF-hand type, S100B, exerts both intracellular and extracellular regulatory activities. As an intracellular regulator, S100B is involved in the regulation of energy metabolism, transcription, protein phosphorylation, cell proliferation, survival, differentiation and motility, and Ca 2+ homeostasis, by interacting with a wide array of proteins (i.e. , enzymes, enzyme substrates, cytoskeletal subunits, scaffold/adaptor proteins, transcription factors, ubiquitin E3 ligases, ion channels) in a restricted number of cell types. As an extracellular signal, S100B engages the pattern recognition receptor, receptor for advanced glycation end-products (RAGE), on immune cells as well as on neuronal, astrocytic and microglial cells, vascular smooth muscle cells, skeletal myoblasts and cardiomyocytes. However, RAGE may not be the sole receptor activated by S100B, the protein being able to enhance bFGF-FGFR1 signaling by interacting with FGFR1-bound bFGF in particular cell types. Moreover, extracellular effects of S100B vary depending on its local concentration. Increasing evidence suggests that at the concentration found in extracellular fluids in normal physiological conditions and locally upon acute tissue injury, which is up to a few nM levels, S100B exerts trophic effects in the central and peripheral nervous system and in skeletal muscle tissue thus participating in tissue homeostasis. The present commentary summarizes results implicating intracellular and extracellular S100B in tissue development, repair and regeneration. S100B belongs to a multigenic family of small (mol. wt. between 9 kDa and 14 kDa) Ca 2+ -binding proteins of the EF-hand type comprising more than 20 members exclusively expressed in vertebrates [1,2] . Like other members of this protein family, S100B is expressed in a cell-specific
Cell Calcium, 2019
Two highly conserved structural motifs observed in members of the EF-hand family of calcium binding proteins. The motifs provide a supporting scaffold for the Ca2+ binding loops and contribute to the hydrophobic core of the EF-hand domain. Each structural motif represents a cluster of three amino acids called cluster I ('black' cluster) and cluster II ('grey' cluster). Cluster I is more conserved and mostly incorporates aromatic amino acids. In contrast, cluster II is noticeably less conserved and includes a mix of aromatic, hydrophobic, and polar amino acids of different sizes. In the human calcium binding S100 P protein, these 'black' and 'gray' clusters include residues F15, F71, and F74 and L33, L58, and K30, respectively. To evaluate the effects of these clusters on structure and functionality of human S100 P, we have performed Ala scanning. The resulting mutants were studied by a multiparametric approach that included circular dichroism, scanning calorimetry, dynamic light scattering, chemical crosslinking, and fluorescent probes. Spectrofluorimetric Ca2+-titration of wild type S100 P showed that S100 P dimer has 1-2 strong calcium binding sites (K 1 = 4 × 106 M −1) and two cooperative low affinity (K 2 = 4 × 104 M −1) binding sites. Similarly, the S100 P mutants possess two types of calcium binding sites. This analysis revealed that the alanine substitutions in the clusters I and II caused comparable changes in the S100 P functional properties. However, analysis of heat-or GuHCl-induced unfolding of these proteins showed that the alanine substitutions in the cluster I caused notably more pronounced decrease in the protein stability compared to the changes caused by alanine substitutions in the cluster II. Opposite to literature data, the F15 A substitution did not cause the S100 P dimer dissociation, indicating that F15 is not crucial for dimer stability. Overall, similar to parvalbumins, the S100 P cluster I is more important for protein conformational stability than the cluster II. 1. Introduction Calcium-binding proteins, which are grouped into several large families [1,2], play important roles in practically all biological processes. One of the most studied families of calcium-binding proteins is the EF-hand protein superfamily (reviewed in [2]). The EF-hand
S100A1 (S100 calcium binding protein A1)
Atlas of Genetics and Cytogenetics in Oncology and Haematology, 2012
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Human S100A12: a novel key player in inflammation?
Amino Acids, 2009
S100A12 is a member of the S100 family of EF-hand calcium-binding proteins. Human S100A12 is predominantly expressed and secreted by neutrophil granulocytes and, therefore, has been assigned to the S100 protein subfamily of calgranulins or myeloid-related proteins. Intracellular S100A12 exists as an anti-parallel homodimer and upon calcium-dependent activation interacts with target proteins to regulate cellular functions. Extracellular S100A12 exists majorily as homodimer and hexamer, respectively, and shows cytokine-like characteristics. It is part of the innate immune response and linked to certain autoimmune reactions. Human S100A12 is markedly overexpressed in inflammatory compartments, and elevated serum levels of S100A12 are found in patients suffering from various inflammatory, neurodegenerative, metabolic, and neoplastic disorders. In this regard, interaction of calcium-activated S100A12 with the multiligand receptor for advanced glycation endproducts (RAGE) and its soluble form (sRAGE) plays a central pathogenetic role. Recent clinical evidence suggests a high potential of S100A12 as a sensitive and specific diagnostic marker of localized inflammatory processes.
Multifunctional Role of S100 Protein Family in the Immune System: An Update
Cells
S100 is a broad subfamily of low-molecular weight calcium-binding proteins (9–14 kDa) with structural similarity and functional discrepancy. It is required for inflammation and cellular homeostasis, and can work extracellularly, intracellularly, or both. S100 members participate in a variety of activities in a healthy cell, including calcium storage and transport (calcium homeostasis). S100 isoforms that have previously been shown to play important roles in the immune system as alarmins (DAMPs), antimicrobial peptides, pro-inflammation stimulators, chemo-attractants, and metal scavengers during an innate immune response. Currently, during the pandemic, it was found that several members of the S100 family are implicated in the pathophysiology of COVID-19. Further, S100 family protein members were proposed to be used as a prognostic marker for COVID-19 infection identification using a nasal swab. In the present review, we compiled the vast majority of recent studies that focused on th...