Biomedical subjects

Paul Perry

Publications and source records attributed to Paul Perry.

7 recordsLinked to original sources

PubMed2004

Altered protein dynamics of disease-associated lamin A mutants.

BACKGROUND: Recent interest in the function of the nuclear lamina has been provoked by the discovery of lamin A/C mutations in the laminopathy diseases. However, it is not understood why mutations in lamin A give such a range of tissue-specific phenotypes. Part of the problem in rationalising genotype-phenotype correlations in the laminopathies is our lack of understanding of the function of normal and mutant lamin A. To investigate this we have used photobleaching in human cells to analyse the dynamics of wild-type and mutant lamin A protein at the nuclear periphery. RESULTS: We have found that a large proportion of wild-type lamin A at the nuclear periphery is immobile, but that there is some slow movement of lamin A within the nuclear lamina. The mobility of an R482W mutant lamin A was indistinguishable from wild-type, but increased mobility of L85R and L530P mutant proteins within the nuclear lamina was found. However, the N195K mutant shows the most enhanced protein mobility, both within the nucleoplasm and within the lamina. CONCLUSION: The slow kinetics of lamin A movement is compatible with its incorporation into a stable polymer that only exchanges subunits very slowly. All of the myopathy-associated lamin A mutants that we have studied show increased protein movement compared with wild-type. In contrast, the dynamic behaviour of the lipodystrophy-associated lamin A mutant was indistinguishable from wild-type. This supports the hypothesis that the underlying defect in lamin A function is quite distinct in the laminopathies that affect striated muscle, compared to the diseases that affect adipose tissue. Our data are consistent with an alteration in the stability of the lamin A molecules within the higher-order polymer at the nuclear lamina in myopathies.

Cell Line, Tumor↗

PubMed2004

Nuclear organization of centromeric domains is not perturbed by inhibition of histone deacetylases.

It is well established that modification of lysines in histone molecules correlates with gene expression and chromatin structure. It is not known whether this operates entirely at a local level, e.g. through the recruitment of specific proteins, or whether histone modifications might impact on more long-range aspects of chromatin organization. There is a distinctive organization of chromatin within the nucleus and the chromatin at the nuclear periphery of mammalian cells appears to be hypoacetylated. Previously it had been suggested that inhibition of histone deacetylases by TSA causes a gross remodeling of nuclear structure, specifically the recruitment of centromeric heterochromatin to the nuclear periphery. Here, we have quantified the nuclear organization of histone modifications and the localization of centromeric domains in human cells before and after TSA treatment. TSA alters the nuclear distribution of histone acetylation, but not that of histone methylation. TSA elevates levels of histone acetylation at the nuclear periphery but we see no alteration in the position of centromeric domains in the nuclei of treated cells. We conclude that the distinctive nuclear localization of centromeric domains is independent of histone acetylation.

Acetylation↗

PubMed2004

Mapping of a discontinuous and highly conformational binding site on follicle stimulating hormone subunit-beta (FSH-beta) using domain Scan and Matrix Scan technology.

This paper describes the application of two novel screening technologies, i.e. Domain Scan (24- and 30-mer peptides) and Matrix Scan (24-mer peptides) technology, in the mapping of a discontinuous epitope on FSH-beta for a series of 20 monoclonal antibodies. 11 out of 20 mAb's, mapping of which was not successful by conventional Pepscan technology (12-mer peptides), showed selective binding to peptide-constructs corresponding to the beta3-loop of FSH in the Domain and/or Matrix Scan. Systematic replacement analysis studies with peptide-construct 57VYETVRVPGCAC-SAc-ADSLYTYPVATQ81 revealed that for most mAb's the amino acids R62, A70, D71, and L73 form the core of the epitope. A Domain Scan performed in the C-O format showed highly selective binding for mAb's 1 and 2 with only three beta1-beta3 peptide-constructs covering the residues 60TVRVPGCAHHADSLY74 in combination with 10IAIEKEECRFAI21, while for mAb 10 binding was observed with peptide-constructs containing the C-terminal residues 97RGLGPSYCSFGEMKE114 in combination with the residues 10IAIEKEECRFAI21. A Matrix Scan of mAb 17 showed that peptides from four different regions on FSH (1st strand beta3-loop, alpha 1-loop, long alpha2-loop, det. loop) showed enhanced binding in combination with several 70ADSL73-containing peptides. BIACORE measurements with mAb's 1, 2, 13, and 17 using a set of 21 different peptide(-construct)s partially confirmed the Domain and Matrix Scan screening results. Only 24- and 33-mer peptides covering both the 1st and 2nd strand of the beta3-loop showed measurable binding. Cyclic beta3-loop peptide mimics were found to bind significantly stronger (Kd approximately 5 microM) than the lineair analogues, in agreement with the fact that the discontinuous epitope is part of a loop structure. Coupling of the lineair beta1-peptide 1oIAIEKEECRFAI21 to the linear beta3-peptide *52TFKELVYETVRVPGCAHHADSLYTYPVATQAH83# via disulfide bond formation showed a 2-3 fold increase in Kd, thus conforming participation of the beta 1-loop in antibody binding for these mAb's.

Amino Acid Sequence↗

PubMed2003

5-HT2A receptor promoter polymorphism, -1438G/A and negative symptom response to olanzapine in schizophrenia.

The 5-HT2A receptor promoter -1438G/A polymorphism, which is in complete linkage disequilibrium with the 5-HT2A 102T/C polymorphism, may be related to antipsychotic response. The aim of this paper is to determine relationships between the -1438G/A polymorphism and olanzapine negative symptom response. DNA from 41 subjects with schizophrenia (as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) was analyzed for the -1438G/A polymorphism. Olanzapine (7.5-20 mg/day) was given for 6 weeks and response was assessed using the Scale for Assessment of Negative Symptoms (SANS). A linear regression used a dependent variable of percent change in SANS. Independent variables included 5-HT2A polymorphisms and interactions. The -1438G/A polymorphism and percent change in SANS showed a significant trend (P=.0542). The A/A genotype group had a 45% reduction in SANS compared with 19% in the other groups. We conclude that the A/A genotype may be associated with olanzapine negative symptom response, seen as a 2-fold greater percent reduction in SANS, and may be clinically relevant.

Antipsychotic Agents↗

PubMed2002

Optical projection tomography as a tool for 3D microscopy and gene expression studies.

Current techniques for three-dimensional (3D) optical microscopy (deconvolution, confocal microscopy, and optical coherence tomography) generate 3D data by "optically sectioning" the specimen. This places severe constraints on the maximum thickness of a specimen that can be imaged. We have developed a microscopy technique that uses optical projection tomography (OPT) to produce high-resolution 3D images of both fluorescent and nonfluorescent biological specimens with a thickness of up to 15 millimeters. OPT microscopy allows the rapid mapping of the tissue distribution of RNA and protein expression in intact embryos or organ systems and can therefore be instrumental in studies of developmental biology or gene function.

Anatomy, Cross-Sectional↗

PubMed2002

Chromatin motion is constrained by association with nuclear compartments in human cells.

BACKGROUND: In comparison with many nuclear proteins, the movement of chromatin in nuclei appears to be generally constrained. These restrictions on motion are proposed to reflect the attachment of chromatin to immobile nuclear substructures. RESULTS: To gain insight into the regulation of chromosome dynamics by nuclear architecture, we have followed the movements of different sites in the human genome in living cells. Here, we show that loci at nucleoli or the nuclear periphery are significantly less mobile than other, more nucleoplasmic loci. Disruption of nucleoli increases the mobility of nucleolar-associated loci. CONCLUSIONS: This is the first report of distinct nuclear substructures constraining the movements of chromatin. These constraints reflect the physical attachment of chromatin to nuclear compartments or steric impairment caused by local ultrastructure. Our data suggest a role for the nucleolus and nuclear periphery in maintaining the three-dimensional organization of chromatin in the human nucleus.

Bacterial Proteins↗

PubMedDate not supplied

A regional comparison of developing diabetes among VA patients exposed to typical and atypical antipsychotics relative to corticosteroids and proton pump inhibitors.

BACKGROUND: Metabolic changes, including weight gain and onset of diabetes, have been associated with both systemic corticosteroid use and atypical antipsychotic drugs. The purpose of this study was to quantify and compare the risk of new-onset diabetes mellitus in a Veterans Affairs population receiving antipsychotics and corticosteroids, using persons taking proton pump inhibitors as a control group. METHODS: This study included data from subjects treated within Veterans Integrated Service Network 23 who had received an outpatient prescription in fiscal years (FY) 1999 or 2000 for a corticosteroid (CS), a proton pump inhibitor (PPI), a typical antipsychotic, or an atypical antipsychotic. Patients receiving prescriptions in more than one class were not excluded. Subjects were excluded if they had a documented diagnosis of diabetes either in the previous FY year (1998) or prior to their index prescription date. RESULTS: Thirteen percent of the population had a new diagnosis for diabetes during the two-year study. Cox-regression analysis using time dependent covariates determined a significantly higher risk of developing diabetes (RR = 1.21) in users of CS relative to PPIs. Demographic variables including age, race, gender, marital status, and VA financial classification as well as a marker for schizophrenia, were also included in the model. Comparison of both typical and atypical antipsychotics to PPIs found an increased but nonsignificant risk of developing diabetes (RR = 1.18 and RR = 1.19 respectively). CONCLUSIONS: The diabetogenic risk associated with atypical antipsychotics was found to be less than that of corticosteroids when compared to controls. Periodic monitoring of blood glucose should be considered with chronic use of an agent from either class.

Adrenal Cortex Hormones↗