Pharmacogenomics Of Antipsychotics Risperidone And Molecular Genetics Of Hypertension

Schizophrenia (OMIM181500), a common and severe psychiatricdisorder, has80–85％heritability. Risperidone, a benzisoxazolederivative, is widely used as a first-line medication for treatment andmaintenance therapy in schizophrenia and related psychotic disorders. Asone of second generation antipsychotics, risperidone has severaladvantages, including a lower incidence of extrapyramidal side effects(EPS), a more frequent clinically significant improvement, awider-ranging effect on both positive and negative symptoms, a lowerrisk of relapse, and a very low risk of tardive dyskinesia (TD). However,there are considerable individual differences in response to risperidone, interms of both therapeutic effects and adverse side effects. Geneticpolymorphisms of genes involved in pharmacokinetics andpharmacodynamics have been found to contribute to variability in drugresponse. However, previous pharmacogenomic studies could explainonly a part of response variability of risperidone.In the first part of this thesis, we examined the effect of serotoninreceptor7gene (HTR7), histamine receptor H3gene (HRH3) andhistamine receptor H4gene (HRH4) on clinical efficacy of eight-week risperidone monotherapy in130Chinese Han schizophrenia in-patients.Changes of Brief Psychiatric Rating Scale (BPRS) and Positive andNegative Syndrome Scale (PANSS) denoted risperidone efficacy, onwhich genetic effects were evaluated using statistical methods, includingchi-square analysis, ANOVA (analysis of variance), haplotype analysisand ROC (Receiver Operating Characteristics) analysis. HTR7geneshowed no significant association with risperidone response. Both tagSNPs of HRH3gene were significantly associated with risperidoneefficacy. Significant association of HRH4gene with risperidone efficacywas also detected. Our results provide the first evidence that HRH3andHRH4polymorphisms may be molecular markers for the prediction ofrisperidone efficacy and suggest novel pharmacological links betweenhistamine receptor genes and treatment of schizophrenia.Essential hypertension (OMIM145500) is the most common type ofhypertension, affecting about95％of hypertensive patients.Hypertension, e.g. high blood pressure, is a major risk factor for stroke,myocardial infarction, heart failure, aortic aneurysm, peripheral arterialdisease and is a cause of chronic kidney disease. Autonomic nervoussystem is believed to play a crucial role in hypertension, although detailedphysiology is still unclear. It is acknowledged that many signal pathwaysmay be involved, including rennin-angiotensin system, catecholamine-epinephrine system, Peptide YY-neuropeptide Y systemand chromogranin A-catestatin system.In the second part of this thesis, we first focused on investigatingwhether there were naturally occurring genetic variations at the Y2receptor (NPY2R), and whether such variations could be translated intopathophysiological significance by functional testing. We undertooksystematic polymorphism discovery across the locus. Commonpolymorphisms were found principally in the proximal promoter;3promoter variants, in particular, each altered gene expression in luciferasereporter constructs in cells. Each of these three variants disrupted thebinding of a known transcription factor, and such processes were verifiedat each SNP site by co-expression of both the candidate factor and aspecific siRNA directed against the factor. We conclude that commonvariants in the NPY2R proximal promoter are functional polymorphismsthat may be causally associated with cardio-metabolic disease risk in thepopulation.Then, we investigated the molecular function of ATP6V0A1variantwhich was previously found in high linkage with catestatin plasma levelin population. Using luciferase reporter system and in vitrotranscription/translation system,3’-UTR variant T+3246C was found toinfluence gene expression. Such effect resulted from different bindingenergies to microRNA hsa-miR-637, verified by cotransfection of hsa-miR-637precursor or antagomir/inhibitor oligonucleotides. Asexpected from the function of ATP6V0A1as a crucial part of vesicularH+-ATPase, chromaffin granule pH, monitored by fluorescence ofCHGA/EGFP chimera, was different between T and C alleles. Elevatedvesicular pH after bafilomycin A1treatment diminished the ratio ofchromogranin A precursor to its catestatin fragments in PC12cells,though the qualitative composition of such fragments was not affected(on immunoblot or matrix-assisted laser desorption ionization (MALDI)mass spectrometry). Bafilomycin A1treatment also decreased exocytoticsecretion from the regulated pathway, monitored by a CHGA chimeratagged with embryonic alkaline phosphatase. The results point to newmolecular and mRNA translational strategies for probing autonomiccontrol of the circulation and ultimately the susceptibility to andpathogenesis of cardiovascular disease states such as hypertension.