OBJECTIVETo review and summarize literature regarding stimulatory and inhibitory signaling pathways from different types of Fc gamma receptors (FcgammaRs).

DATA SOURCEArticles were obtained from Medline from January 1991 to April 2002.

STUDY SELECTIONOver 100 English language papers and reviews published over the last 11 years were selected.

RESULTS AND CONCLUSIONSStimulatory Fcgamma receptors include FcgammaRI, FcgammaRIIA, FcgammaRIIC, and FcgammaRIII A. They transduce signals through the immunoreceptor tyrosine-based activation motif (ITAM) in subunits or in the cytoplasmic domain. Inhibitory Fcgamma receptors, such as FcgammaRIIB, are single chain receptors, transducing signals through an immunoreceptor tyrosine-based inhibitory motif (ITIM) in cytoplasmic domains. Stimulatory signals include protein phosphorylation, increase in intracellular free calcium, the production of 1,4,5-triphosphate inositol (IP(3)) and diacylglycerol (DAG) mainly through the Src-family kinases, phosphoinositide 3-kinase (PI3-K) and phospholipase C (PLC). Inhibitory signaling has been implicated in the repression of the above activities as well as inhibition of B cell responses through Src homology 2-containing inositol phosphatase (SHIP).

Amino Acid Motifs ; Animals ; Blood Platelets ; physiology ; Humans ; Phagocytes ; physiology ; Receptors, IgG ; chemistry ; physiology ; Signal Transduction ; physiology

KM-HN-1 is a C-terminal coiled-coil domain containing protein previously referred to as image clone MGC33607. This protein has been previously identified as a cancer/testis antigen and reported as nuclear and chromatin localizing protein. We raised polyclonal antisera with the GST fusion protein and identified them as a 105 kDa protein. Motif analysis showed that this protein harbors the leucine zipper motif in internal 1/3 region and the coiled-coil domain in the C-terminal region. Using the full length and various deletion mutants, we determined the motif that governs the subcellular localization of KM-HN-1. Immunofluorescence staining of the endogenous KM-HN-1 and various kinds of GFP-tagged KM-HN-1 revealed that KM-HN-1 localizes to the centrosomes as well as nucleus. The centrosomal localization-determining region of this protein is C-terminal coiled-coil domain in which the leucine zipper motif and the nuclear export signal (NES) harbor.
Amino Acid Motifs/physiology ; Amino Acid Sequence ; Antigens, Neoplasm/chemistry/*metabolism ; Cells, Cultured ; Centrosome/*metabolism ; Fluorescent Antibody Technique ; Humans ; Leucine Zippers/*physiology ; Molecular Sequence Data ; Mutation ; Nuclear Proteins/chemistry/*metabolism ; Protein Conformation ; Protein Structure, Tertiary ; Sequence Analysis, Protein

The largest subunit of eukaryotic RNA polymerase II contains a unique domain at its carboxy-terminus, which is referred to as the carboxy-terminal domain (CTD). The CTD is made up of an evolutionarily conserved heptapeptide repeat (YSPTSPS). Over the past decade, there has been increasing attention on the role of the CTD in transcription regulation in the view of mRNA processing and chromatin remodeling. This paper provides a brief overview of the recent progress in the dynamic changes in CTD phosphorylation and its role in integrating multiple nuclear events.
Amino Acid Motifs ; Amino Acid Sequence ; Animals ; Chromatin/*physiology ; Chromatin Assembly and Disassembly ; Conserved Sequence ; Histones/metabolism ; Humans ; Isomerism ; Phosphorylation ; Protein Structure, Tertiary ; RNA Polymerase II/chemistry/*physiology ; RNA, Messenger/metabolism ; Transcription, Genetic

OBJECTIVETo study the relationship between the structure and functional activity of hTNF alpha.

METHODSFour hTNF alpha mutants were constructed, different binding structures and gene responses related with these mutants were studied by the methods of immunoprecipitation and mRNA differential display.

RESULTSThe specific activities and LD50 of the different hTNF alpha mutants indicated their different bioactivities. It was shown that the hTNF alpha mutants had the relative binding affinities to the wild types. The mRNA differential display assay proved that the hTNF alpha mutants stimulated different gene responses.

CONCLUSIONThese results suggest that the specific anti-tumor activities of hTNF alpha mutants are accomplished by inducing different or same gene response at different quantities after its binding to specific receptor.

Amino Acid Motifs ; Apoptosis ; Binding Sites ; Gene Expression Profiling ; Humans ; Molecular Structure ; Mutation ; Structure-Activity Relationship ; Tumor Necrosis Factor-alpha ; genetics ; physiology

This study was performed to investigate the effects of different regions of the Autographa califor nica multiple nucleopolyhedrovirus envelope protein E25 on its trafficking into nucleus and nuclear localization in host cells and on virus replication. Fourteen recombinant bacmids, each containing an e25 mutant with substitution or insertion of egfp, in the absence or presence of the native e25, were constructed and used to transfect Sf9 cells. The E25-EGFP fusion proteins and native E25 expressed in the cells transfect ed with individual recombinant bacmid were traced by autofluorescence from EGFP or by immuno-fluorescence assays. Confocal microscopy revealed that the E25-EGFP fusion protein with the N-domain (2-45aa) of E25 substituted by EGFP only distributed in the cytoplasm in transfected cells; and the fusion protein with EGFP inserted at the laa/2aa site of E25 completely remained outside of the nucleus and resided along the nuclear membrane. The E25-EGFPs with 46-118aa of E25 substituted by EGFP or with EGFP inserted at the 118aa/119aa site were present outside, across from the nuclear membrane or in nuclear plasm in dot-like shapes. The fusion proteins with the C-domain substituted by EGFP or with EGFP inserted at the site of 45/46aa or at the C-terminal formed a condensed ring or spread throughout the nucleus, in a similar manner to the E25 distributed in the cells transfected by the e25-knockout repair bacmid. These results prove that the N-terminal domain is critical for nuclear transportation of E25 and possibly to its position on the cytoplasm membrane as well; and the sequence downstream of the N-terminal domain also affects trafficking and nuclear localization of the protein. In cells transfected with bacmids containing both the native e25 and individual e25-egfp mutants, the E25-EGFP fusion proteins co-localized with E25 individually, showing similar patterns of subcellular localization as E25 mutants in the absence of native E25 in most cases, suggesting that the E25 likely exists and functions as dimmers or polymers. Production of infectious BV was dramatically reduced and even completely eliminated in most cases, either in the absence or presence of the native e25.
Amino Acid Motifs ; Animals ; Cell Nucleus ; metabolism ; virology ; Mutation ; Nucleopolyhedrovirus ; chemistry ; genetics ; physiology ; Protein Transport ; Spodoptera ; virology ; Viral Proteins ; chemistry ; genetics ; metabolism ; Virus Release ; Virus Replication

The important and diverse regulatory roles of Ca(2+) in eukaryotes are conveyed by the EF-hand containing calmodulin superfamily. However, the calcium-regulatory proteins in prokaryotes are still poorly understood. In this study, we report the three-dimensional structure of the calcium-binding protein from Streptomyces coelicolor, named CabD, which shares low sequence homology with other known helix-loop-helix EF-hand proteins. The CabD structure should provide insights into the biological role of the prokaryotic calcium-binding proteins. The unusual structural features of CabD compared with prokaryotic EF-hand proteins and eukaryotic sarcoplasmic calcium-binding proteins, including the bending conformation of the first C-terminal α-helix, unpaired ligand-binding EF-hands and the lack of the extreme C-terminal loop region, suggest it may have a distinct and significant function in calcium-mediated bacterial physiological processes, and provide a structural basis for potential calcium-mediated regulatory roles in prokaryotes.
Amino Acid Sequence ; Binding Sites ; Calcium ; physiology ; Calcium-Binding Proteins ; chemistry ; Crystallography, X-Ray ; EF Hand Motifs ; Molecular Sequence Data ; Protein Binding ; Protein Structure, Tertiary ; Sequence Alignment ; Sequence Homology, Amino Acid ; Streptomyces coelicolor ; Structural Homology, Protein ; Surface Properties

The importance of NAC (named as NAM, ATAF1, 2, and CUC2) proteins in plant development, transcription regulation and regulatory pathways involving protein-protein interactions has been increasingly recognized. We report here the high resolution crystal structure of SNAC1 (stress-responsive NAC) NAC domain at 2.5 Å. Although the structure of the SNAC1 NAC domain shares a structural similarity with the reported structure of the ANAC NAC1 domain, some key features, especially relating to two loop regions which potentially take the responsibility for DNA-binding, distinguish the SNAC1 NAC domain from other reported NAC structures. Moreover, the dimerization of the SNAC1 NAC domain is demonstrated by both soluble and crystalline conditions, suggesting this dimeric state should be conserved in this type of NAC family. Additionally, we discuss the possible NAC-DNA binding model according to the structure and reported biological evidences.
Amino Acid Motifs ; Amino Acid Sequence ; Conserved Sequence ; Crystallography, X-Ray ; DNA ; metabolism ; Models, Molecular ; Molecular Sequence Data ; Oryza ; metabolism ; physiology ; Plant Proteins ; chemistry ; metabolism ; Promoter Regions, Genetic ; genetics ; Protein Multimerization ; Protein Structure, Quaternary ; Protein Structure, Tertiary ; Stress, Physiological

OBJECTIVETo study the role of HLB-1 in regulating the organization and function of neuromuscular junctions in nematode Caenorhabditis elegans.

METHODSTo evaluate the functions of HLB-1 in regulating the organization and function of neuromuscular junctions, effects of hlb-1 mutation on the synaptic structures were revealed by uncovering the expression patterns of SNB-1::GFP and UNC-49::GFP, and pharmacologic assays with aldicarb and levamisole were also used to test the synaptic functions. Further rescue and mosaic analysis confirmed HLB-1's role in regulating the organization and function of neuromuscular junctions.

RESULTSLoss of HLB-1 function did not result in defects in neuronal outgrowth or neuronal loss, but caused obvious defects of SNB-1::GFP and UNC-49::GFP puncta localization, suggesting the altered presynaptic and postsynaptic structures. The mutant animals exhibited severe defects in locomotion behaviors and altered responses to an inhibitor of acetylcholinesterase and a cholinergic agonist, indicating the altered presynaptic and postsynaptic functions. Rescue and mosaic analysis experiments suggested that HLB-1 regulated synaptic functions in a cell nonautonomously way. Moreover, HLB-1 expression was not required for the presynaptic active zone morphology. Genetic evidence further demonstrated that hlb-1 acted in a parallel pathway with syd-2 to regulate the synaptic functions.

CONCLUSIONHLB-1 appeared as a new regulator for the organization and function of neuromuscular junctions in C. elegans.

Age Factors ; Amino Acid Motifs ; physiology ; Analysis of Variance ; Animals ; Animals, Genetically Modified ; Animals, Newborn ; Behavior, Animal ; physiology ; Caenorhabditis elegans ; Caenorhabditis elegans Proteins ; genetics ; metabolism ; physiology ; Carrier Proteins ; metabolism ; Cell Adhesion Molecules ; genetics ; physiology ; Green Fluorescent Proteins ; genetics ; Locomotion ; genetics ; Mutation ; physiology ; Neuromuscular Junction ; genetics ; physiology ; Phosphoproteins ; genetics ; physiology

An extracellular matrix protein plays an important role in skin wound healing. In the present study, we engineered a recombinant protein encompassing the 9th and 10th type III domains of fibronectin, and 4th FAS1 domain of beta ig-h3. This recombinant protein, in total, harbors four known-cell adhesion motifs for integrins: Pro-His-Ser-Arg-Asn (PHSRN) and Arg-Gly-Asp (RGD) in 9th and 10th type III domains of fibronectin, respectively, and Glu-Pro-Asp-Ile-Met (EPDIM) and Try-His (YH) in 4th FAS1 domain of big-h3, were designated to tetra-cell adhesion motifs (T-CAM). In vitro studies showed T-CAM supporting adhesion, migration and proliferation of different cell types including keratinocytes and fibroblasts. In an animal model of full-thickness skin wound, T-CAM exhibited excellent wound healing effects, superior to both 4th FAS1 domain of beta ig-h3 or 9th and 10th type III domains of fibronectin. Based on these results, T-CAM can be applied where enhancement of cell adhesion, migration and proliferation are desired, and it could be developed into novel wound healing drug.
Amino Acid Motifs ; Animals ; Cell Adhesion/*drug effects ; Cell Line ; Cell Movement/*drug effects ; Cell Proliferation/*drug effects ; Extracellular Matrix Proteins/chemistry/genetics/pharmacology ; Fibroblasts/cytology/drug effects/physiology ; Fibronectins/chemistry/genetics/*pharmacology ; Humans ; Keratinocytes/cytology/drug effects/physiology ; Mice ; NIH 3T3 Cells ; Rabbits ; Recombinant Fusion Proteins/chemistry/genetics/pharmacology ; Transforming Growth Factor beta/chemistry/genetics/pharmacology ; Wound Healing/*drug effects/physiology

Betaig-h3 (betaig-h3) is a secretory protein composed of fasciclin I-like repeats containing sequences that allows binding of integrins and glycosaminoglycans in vivo. Expression of betaig-h3 is responsive to TGF-beta and the protein is found to be associated with extracellular matrix (ECM) molecules, implicating betaig-h3 as an ECM adhesive protein of developmental processes. We previously observed predominant expression of betaig-h3 expression in the basement membrane of proximal tubules of kidney. In this study, the physiological relevance of such localized expression of betaig-h3 was examined in the renal proximal tubular epithelial cells (RPTEC). RPTEC constitutively expressed betaig-h3 and the expression was dramatically induced by exogenous TGF-beta1 treatment. betaig-h3 and its second and fourth FAS1 domain were able to mediate RPTEC adhesion, spreading and migration. Two known alpha3beta1 integrin-interaction motifs including aspartatic acid and isoleucine residues, NKDIL and EPDIM in betaig-h3 were responsible to mediate RPTEC adhesion, spreading, and migration. By using specific antibodies against integrins, we confirmed that alpha3beta1 integrin mediates the adhesion and migration of RPTECs on betaig-h3. In addition, it also enhanced proliferation of RPTECs through NKDIL and EPDIM. These results indicate that betaig-h3 mediates adhesion, spreading, migration and proliferation of RPTECs through the interaction with alpha3beta1 integrin and is intimately involved in the maintenance and the regeneration of renal proximal tubular epithelium.
Amino Acid Motifs ; Antibodies, Blocking/immunology ; Cell Adhesion/physiology ; Cell Movement/physiology ; Cell Proliferation ; Cells, Cultured ; Epithelial Cells/drug effects ; Extracellular Matrix Proteins/chemistry/immunology/*metabolism ; Humans ; Integrin alpha3beta1/chemistry/immunology/*metabolism ; Kidney Tubules, Proximal/cytology/metabolism/*physiology ; Peptides/chemistry/metabolism ; Protein Interaction Mapping ; Research Support, Non-U.S. Gov't ; Transforming Growth Factor beta/chemistry/immunology/*metabolism/pharmacology