Proteomic analysis of the anti-inflammatory action of minocycline.

Minocycline possesses anti-inflammatory properties independently of its antibiotic activity although the underlying molecular mechanisms are unclear. Lipopolysaccharide (LPS)-induced cytokines and pro-inflammatory protein expression are reduced by minocycline in cultured macrophages. Here, we tested a range of clinically important tetracycline compounds (oxytetracycline, doxycycline, minocycline and tigecycline) and showed that they all inhibited LPS-induced nitric oxide production. We made the novel finding that tigecycline inhibited LPS-induced nitric oxide production to a greater extent than the other tetracycline compounds tested. To identify potential targets for minocycline, we assessed alterations in the macrophage proteome induced by LPS in the presence or absence of a minocycline pre-treatment using 2-DE and nanoLC-MS. We found a number of proteins, mainly involved in cellular metabolism (ATP synthase ß-subunit and aldose reductase) or stress response (heat shock proteins), which were altered in expression in response to LPS, some of which were restored, at least in part, by minocycline. This is the first study to document proteomic changes induced by minocycline. The observation that minocycline inhibits some, but not all, of the LPS-induced proteomic changes shows that minocycline specifically affects some signalling pathways and does not completely inhibit macrophage activation.

Functional and biophysical analysis of the C-terminus of the CGRP-receptor; a family B GPCR.

G-protein coupled receptors (GPCRs) typically have a functionally important C-terminus which, in the largest subfamily (family A), includes a membrane-parallel eighth helix. Mutations of this region are associated with several diseases. There are few C-terminal studies on the family B GPCRs and no data supporting the existence of a similar eighth helix in this second major subfamily, which has little or no sequence homology to family A GPCRs. Here we show that the C-terminus of a family B GPCR (CLR) has a disparate region from N400 to C436 required for CGRP-mediated internalization, and a proximal region of twelve residues (from G388 to W399), in a similar position to the family A eighth helix, required for receptor localization at the cell surface. A combination of circular and linear dichroism, fluorescence and modified waterLOGSY NMR spectroscopy (SALMON) demonstrated that a peptide mimetic of this domain readily forms a membrane-parallel helix anchored to the liposome by an interfacial tryptophan residue. The study reveals two key functions held within the C-terminus of a family B GPCR and presents support for an eighth helical region with striking topological similarity to the nonhomologous family A receptor. This helix structure appears to be found in most other family B GPCRs.

Association of the dysbindin gene with bipolar affective disorder.

OBJECTIVE: In the study of bipolar affective disorder and schizophrenia, there is some evidence suggesting a phenotypic and genetic overlap between the two disorders. A possible link between bipolar affective disorder and schizophrenia remains arguable, however. The authors hypothesized that dysbindin, which is a probable susceptibility gene for schizophrenia, was associated with bipolar affective disorder and tested this hypothesis using a case-control design study. METHOD: Participants included 213 patients with bipolar I disorder and 197 comparison subjects. In each subject, 10 polymorphisms in the dysbindin gene were genotyped and assessed. RESULTS: Two polymorphisms showed individual genotypic association with bipolar I disorder. Multiple marker haplotypes were more strongly associated, with the rarer of the two common haplotypes being overrepresented in the patients with bipolar affective disorder. A similar finding was reported in patients with schizophrenia in a previous study. CONCLUSIONS: Findings suggest that the human dysbindin gene may play a role in the susceptibility to bipolar affective disorder, which underscores a potentially important area of etiological overlap with schizophrenia. The existence of shared genetic risk factors will, in time, lead to changes in the current nosology of major psychoses.

The high-activity Val allele of the catechol-O-methyltransferase gene predicts greater cognitive deterioration in patients with psychosis.

The objective of this study was to examine whether the functional genetic polymorphism Val158Met in the catechol-O-methyltransferase (COMT) gene influences cognitive deterioration in a sample of patients with psychosis under treatment with atypical antipsychotics. Eighty-seven patients with psychosis were genotyped for this polymorphism and were assessed with three Wechsler Adult Intelligence Scale (WAIS)-III subtests (Vocabulary, Information, and Digit Symbol-Coding). Performance on these three subtests was used to compute a 'cognitive deterioration index', and the effect of COMT genotype on this cognitive deterioration index was examined. A linear relationship between the number of Val alleles and the score on the cognitive deterioration index (i.e. the more Val alleles, the more cognitive deterioration) was observed. These results confirm the role of COMT genotype in the cognition of patients under treatment for psychosis, suggesting that it influences the extent of their cognitive deterioration.

Association between dopamine D3 receptor gene polymorphisms and schizophrenia in an isolate population.

There are several lines of evidence implicating the dopamine D3 receptor in the pathophysiology of schizophrenia. The Ser9Gly polymorphism of the dopamine D3 receptor gene (DRD3) has been the most extensively investigated DRD3 variant in connection with the disease but results have been inconclusive. Recent reports indicate that the Ser9Gly polymorphism is in linkage disequilibrium with other markers, but association studies between DRD3 haplotypes and schizophrenia have had mixed results. Genetic heterogeneity may be one of the causes of contradicting results. In order to clarify the role of DRD3 alterations in the aetiology of disease, we have investigated three D3 genetic variants (Ser9Gly, -205-G/A, -7685-G/C) in a sample of patients with schizophrenia or schizoaffective disorder (N=118) and controls (N=162) recruited from a human isolate from Navarra (Northern Spain) of Basque origin. Although no association was found between the Ser9Gly or the -205-A/G polymorphisms and disease, an excess of allele -7685-C was observed in patients (p=0.002 after correction for multiple analyses). Haplotype analysis shows the three markers to be in strong linkage disequilibrium (p<0.0001) and strongly associated with disease (p<1x 10(-5)). These results may suggest that these polymorphisms exert a combined or synergistic effect on susceptibility to schizophrenia, or are in linkage with an unknown causative factor. However, further replication in independent samples is required.

Clinical applications of pharmacogenetics in psychiatry.

Pharmacogenetic research has identified response-related mutant variants in metabolic enzymes and drug-targeted receptors. Allelic variants of dopaminergic and serotonergic receptors have been associated with clinical outcome and adverse events such as movement disorders. Deficient metabolic enzymes have been related to drug accumulation and toxic events. This information will help to design safer and more efficient drugs. However, the field is moving rapidly towards a new goal: the application of pharmacogenetics as a clinical tool for the prediction of treatment outcome. The first studies in this direction have proved the feasibility of using genetic information for the prediction of response to antipsychotic drugs and to treatment of Alzheimer's disease. New strategies investigating genes related to specific symptoms and side-effects have produced encouraging results that can contribute to the improvement of the levels and accuracy of the predictions. This review tries to summarise recent advances and provides an overview of future clinical applications.