Recent studies have shown that an endogenous lipoperoxidation product, 9-hydroxystearic acid (9-HSA), acts in colon carcinoma cells (HT29) as a growth inhibitor by inducing p21 WAF1 in an immediate-early, p53-independent manner and that p21 WAF1 is required for 9-HSA-mediated growth arrest in HT29 cells. It is conceivable, therefore, to hypothesize that the cytostatic effect induced by this agent is at least partially associated with a molecular mechanism that involves histone deacetylase 1 (HDAC1) inhibition, as demonstrated for sodium butyrate and other specific inhibitors, such as trichostatin A and hydroxamic acids. Here, we show that, after administration, 9-HSA causes an accumulation of hyperacetylated histones and strongly inhibits the activity of HDAC1. The interaction of 9-HSA with the catalytic site of the enzyme has been highlighted by computational modeling of the human HDAC1, using its homolog from the hyperthermophilic Aquifex aeolicus as a template. Consistent with the experimental data, we find that 9-HSA can bind to the active site of the protein, showing that the inhibition of the enzyme can be explained at the molecular level by the ligand-protein interaction. Supplementary key words endogenous lipid peroxidation products • tumor • mass spectrometry • computational modeling 9-Hydroxystearic acid (9-HSA) belongs to the class of endogenous lipid peroxidation by-products that are greatly diminished in tumors and therefore become unable to exert their normal controlling functions on cell division (1). Indeed, in HT29 cells, exogenous administration of 9-HSA at micromolar concentrations results in a significant inhibition of proliferation rate as well as a significant increase of p53-independent p21 WAF1 expression (2). The expression of the cell cycle kinase inhibitor p21 WAF1 is induced in neoplastic cells by histone deacetylase 1 (HDAC1) inhibitors such as phenyl butyrate, sodium butyrate, trichostatin A (TSA), and suberoylanilide hydroxamic acid (SAHA). Increased expression of p21 WAF1 may play a critical role in the growth arrest induced in transformed cells by these agents, and it can be regulated, at least in part, by histone acetylation of the chromatin associated with the p21 WAF1 gene. Histone acetylation and gene activation induced by HDAC1 inhibitors would consequently be selective (3). The mode of action of 9-HSA is similar to that of HDAC inhibitors.Crystallographic studies performed using TSA and SAHA indicate that these compounds inhibit HDAC activity by interacting with the catalytic site, thereby blocking substrate access (4, 5). Short-chain fatty acids, such as phenyl butyrate and phenyl acetate, inhibit HDAC activity and affect the expression of numerous genes with disparate cellular functions (6)(7)(8). These agents have been tested in the clinic, but they suffer from a short plasma half-life as well as from the relatively high (millimolar) concentrations that are required for their action. On the other hand, hydroxamic acids such as TSA, SAHA, m -carboxycinnamic acid ...

Background: Protein kinases are a well defined family of proteins, characterized by the presence of a common kinase catalytic domain and playing a significant role in many important cellular processes, such as proliferation, maintenance of cell shape, apoptosys. In many members of the family, additional non-kinase domains contribute further specialization, resulting in subcellular localization, protein binding and regulation of activity, among others. About 500 genes encode members of the kinase family in the human genome, and although many of them represent well known genes, a larger number of genes code for proteins of more recent identification, or for unknown proteins identified as kinase only after computational studies.

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In jawed vertebrates the V-(D)-J rearrangement is the main mechanism generating limitless variations of antigen-specific receptors, immunoglobulins (IGs), and T-cell receptors (TCRs) from few genes. Once the initial diversity is established in primary lymphoid organs, further diversification occurs in IGs by somatic hypermutation, a mechanism from which rearranged TCR genes were thought to be excluded. Here, we report the locus organization and expression of the T-cell receptor gamma (TCRG) genes in the Arabian camel (Camelus dromedarius). Expression data provide evidence that dromedary utilizes only two TCRG V-J genomic arrangements and, as expected, CDR3 contributes the major variability in the V domain. The data also suggest that diversity might be generated by mutation in the productively rearranged TCRGV genes. As for IG genes, the mutational target is biased toward G and C bases and (A/G/T)G(C/T)(A/T) motif (or DGYW). The replacement and synonymous substitutions (R/S) ratios in TCRGV regions are higher for CDR than for framework region, thus suggesting selection toward amino acid changes in CDR. Using the counterpart human TCR γδ receptor as a template, structural models computed adopting a comparative procedure show that nonconservative mutations contribute to diversity in CDR2 and at the γδ V domain interface. Keywords: Camelus dromedarius · Protein modeling · Somatic hypermutation · T-cell receptor gamma (TCRG) Supporting Information available onlineCorrespondence: Dr. Salvatrice Ciccarese e-mail: ciccarese@biologia.uniba.it IntroductionTo respond to the wide spectrum of antigenic determinants presented by an almost limitless variety of diverse and evolving pathogens, the metazoan immune system developed a striking C 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu Eur. J. Immunol. 2012. 42: 3416-3428 Molecular immunology 3417 variation of immune receptor molecules and diversification mechanisms [1]. In jawed vertebrates, the T-cell response is mediated by signaling from the T-cell receptors αβ and γδ, both encoded by complex multigene families. Genetic information for receptor chains is carried by a germline pool of variable (V), joining (J), and diversity (D) genes that undergo somatic DNA rearrangements to generate receptors with diverse-binding specificity [2]. The "innate-like" γδ T cells have unique features when compared with the more abundant αβ T cells, e.g. a preferential distribution in both epithelial and mucosal sites, an immunoglobulin (IG)-like antigen recognition mechanism in addition to the MHC-restricted one. Moreover, their percentage in peripheral blood cells, depending on age and species, differs strikingly from that of αβ T cells [3]. Artiodactyls are referred to as "γδ-high species" since they exhibit a higher frequency and a wider physiological distribution of γδ T cells with respect to other mammalian species, including humans and mice which are referred to as "γδ-low species" [4]. The locus organization and expression of TCRG and TCRD genes have been charac...