Interaction of the S100A4 (Mts1) protein with septins Sept2, Sept6, and Sept7 in vitro

Overexpression of S100A4 as a biomarker of metastasis and recurrence in oral squamous cell carcinoma

S100A4, a biomarker of epithelial mesenchymal transition (EMT), plays an important role in invasion and metastasis by promoting cancer cell motility. In oral squamous cell carcinoma (OSCC), metastasis results in 90% of cancer associated mortality.

Evidence for somatic gene conversion and deletion in bipolar disorder, Crohn's disease, coronary artery disease, hypertension, rheumatoid arthritis, type-1 diabetes, and type-2 diabetes

BACKGROUND

During gene conversion, genetic information is transferred unidirectionally between highly homologous but non-allelic regions of DNA. While germ-line gene conversion has been implicated in the pathogenesis of some diseases, somatic gene conversion has remained technically difficult to investigate on a large scale.

METHODS

A novel analysis technique is proposed for detecting the signature of somatic gene conversion from SNP microarray data. The Wellcome Trust Case Control Consortium has gathered SNP microarray data for two control populations and cohorts for bipolar disorder (BD), cardiovascular disease (CAD), Crohn's disease (CD), hypertension (HT), rheumatoid arthritis (RA), type-1 diabetes (T1D) and type-2 diabetes (T2D). Using the new analysis technique, the seven disease cohorts are analyzed to identify cohort-specific SNPs at which conversion is predicted. The quality of the predictions is assessed by identifying known disease associations for genes in the homologous duplicons, and comparing the frequency of such associations with background rates.

RESULTS

Of 28 disease/locus pairs meeting stringent conditions, 22 show various degrees of disease association, compared with only 8 of 70 in a mock study designed to measure the background association rate (P < 10-9). Additional candidate genes are identified using less stringent filtering conditions. In some cases, somatic deletions appear likely. RA has a distinctive pattern of events relative to other diseases. Similarities in patterns are apparent between BD and HT.

CONCLUSIONS

The associations derived represent the first evidence that somatic gene conversion could be a significant causative factor in each of the seven diseases. The specific genes provide potential insights about disease mechanisms, and are strong candidates for further study.

Age-related gene expression profiles of rhesus monkey bone marrow-derived mesenchymal stem cells

The objective of this study was to elucidate age-related differences in gene expression profiles of rhesus monkey bone marrow-derived mesenchymal stem cells (rhMSC) obtained from fetal, infant, and adult donors relevant to their growth and other properties. Although a high degree of similarity was observed in the rhMSC gene expression profiles when comparing the three age groups, significant differences were found that strongly parallel gene expression profiles of human MSC. In general, there was a trend towards increased abundance of transcripts associated with differentiation and growth arrest with increasing donor age. Conversely, transcripts involved in RNA processing and the negative regulation of gene expression showed a downward trend with increasing donor age. Overall, the observed gene expression profiles were found to be similar to observations that MSC from older individuals show diminished proliferative capacity. These data highlight the importance of use of non-human primates to study the properties of stem and progenitor cells, and for future therapies.

Calcium-dependent and -independent interactions of the S100 protein family

The S100 proteins comprise at least 25 members, forming the largest group of EF-hand signalling proteins in humans. Although the proteins are expressed in many tissues, each S100 protein has generally been shown to have a preference for expression in one particular tissue or cell type. Three-dimensional structures of several S100 family members have shown that the proteins assume a dimeric structure consisting of two EF-hand motifs per monomer. Calcium binding to these S100 proteins, with the exception of S100A10, results in an approx. 40 degrees alteration in the position of helix III, exposing a broad hydrophobic surface that enables the S100 proteins to interact with a variety of target proteins. More than 90 potential target proteins have been documented for the S100 proteins, including the cytoskeletal proteins tubulin, glial fibrillary acidic protein and F-actin, which have been identified mostly from in vitro experiments. In the last 5 years, efforts have concentrated on quantifying the protein interactions of the S100 proteins, identifying in vivo protein partners and understanding the molecular specificity for target protein interactions. Furthermore, the S100 proteins are the only EF-hand proteins that are known to form both homo- and hetero-dimers, and efforts are underway to determine the stabilities of these complexes and structural rationales for their formation and potential differences in their biological roles. This review highlights both the calcium-dependent and -independent interactions of the S100 proteins, with a focus on the structures of the complexes, differences and similarities in the strengths of the interactions, and preferences for homo- compared with hetero-dimeric S100 protein assembly.

Proteomic analysis of differentially expressed proteins between metastatic and non-metastatic human colorectal carcinoma cell lines

OBJECTIVES

To explore the expressions of metastasis-related proteins between metastatic LS174T and non-metastatic SW480 human colorectal carcinoma cell lines.

METHODS

Two-dimensional gel electrophoresis (2-DE) was applied to separate the total proteins of cells. The silver-stained gels were analysed by 2-DE software Image Master 2D Elite. Selected differential protein spots were identified with peptide mass fingerprinting based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and database searching.

RESULTS

The protein endothelial cell growth factor 1 (platelet-derived), rhotekin protein (RTKN), septin 1, cyclin-dependent kinase 1, sialic acid binding Ig-like lectin 11, tyrosinase-related protein-2, translin-like protein, and DNA directed RNA polymerase II polypeptide J-related gene isoform 2 appeared in metastatic but were not detected in non-metastatic cell lines, whereas integrin-linked kinase-associated protein phosphatase 2C isoform 2, MHC class I promoter binding protein, protein phosphatase 2A regulatory subunit B' (PR 53), carboxypeptidase A5, paired box transcription factor, zinc finger protein 79, and apolipoprotein B-48 were detected in non-metastatic but were absent in metastatic cell lines. In addition, cyclin fold protein 1 variant A and pre-B-cell leukemia transcription factor 1 were lowly expressed in the non-metastatic cell line and were significantly upregulated in the metastatic cell line. These identified proteins were involved in cell growth, motility, invasion, adhesion, apoptosis and tumour immunity, which is associated with distinct aspects of tumour metastasis.

CONCLUSIONS

These data are valuable for the identification of differentially expressed proteins involved in human colorectal carcinoma carcinogenesis and metastasis.

The pathobiology of the septin gene family

Septins are an evolutionarily conserved group of GTP-binding and filament-forming proteins that belong to the large superclass of P-loop GTPases. While originally discovered in yeast as cell division cycle mutants with cytokinesis defects, they are now known to have diverse cellular roles which include polarity determination, cytoskeletal reorganization, membrane dynamics, vesicle trafficking, and exocytosis. Septin proteins form homo- and hetero-oligomeric polymers which can assemble into higher-order filaments. They are also known to interact with components of the cytoskeleton, ie actin and tubulin. The precise role of GTP binding is not clear but a current model suggests that it is associated with conformational changes which alter binding to other proteins. There are at least 12 human septin genes, and although information on expression patterns is limited, most undergo complex alternative splicing with some degree of tissue specificity. Nevertheless, an increasing body of data implicates the septin family in the pathogenesis of diverse disease states including neoplasia, neurodegenerative conditions, and infections. Here the known biochemical properties of mammalian septins are reviewed in the light of the data from yeast and other model organisms. The data implicating septins in human disease are considered and a model linking these data is proposed. It is posited that septins can act as regulatable scaffolds where the stoichiometry of septin associations, modifications, GTP status, and the interactions with other proteins allow the regulation of key cellular processes including polarity determination. Derangements of such septin scaffolds thus explain the role of septins in disease states.