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Brian J Morris

Publications and source records attributed to Brian J Morris.

At least 19 recordsLinked to original sources
PubMed2026

A droplet digital PCR assay targeting 16 human papillomavirus genotypes.

Background. Cervical screening with high-precision assays such as human papillomavirus (HPV) DNA testing is essential for the detection and treatment of precancerous lesions. HPV genotypes have different oncogenic potential and require different clinical management, illustrating the importance of extended genotyping. HPV quantification has demonstrated clinical relevance in both diagnosis and treatment. Objective. To develop a droplet digital PCR assay for the detection and quantification of 16 HPV genotypes, with comparison to a commercial test and validation on clinical samples. Methods. Primers and probes were designed to target the E6 region of 16 HPV genotypes: 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68, 73 and 82. Each target was evaluated to assess performance and reliability using synthetic DNA constructs, quantified international reference standards and clinical screening samples (n=303) genotyped using the Seegene Anyplex II HR HPV Detection assay. Results. Each assay demonstrated high target specificity, without cross-reactivity observed among the HPV genotypes selected. Using international molecular standards, the assay reliably detected high-risk genotypes across serial dilutions, with detection down to the level of one international unit or genome equivalent per microlitre. When applied to clinical samples with and without a histological diagnosis of cervical intraepithelial neoplasia 2 or worse (CIN2+), the assay reliably detected key HPV genotypes, with the exception of 7 of 234 (3%) of HPV-positive samples, all of which exhibited very low viral load. Conclusion. Although previous studies have described digital PCR methods targeting HPV E6, they have typically focused on a limited number of genotypes. This study expands upon existing methodology by introducing a sensitive and specific method for detection and quantification of 16 high-risk and potentially high-risk HPV genotypes.

PCR↗
PubMed2006

XE7: a novel splicing factor that interacts with ASF/SF2 and ZNF265.

Pre-mRNA splicing is performed by the spliceosome. SR proteins in this macromolecular complex are essential for both constitutive and alternative splicing. By using the SR-related protein ZNF265 as bait in a yeast two-hybrid screen, we pulled out the uncharacterized human protein XE7, which is encoded by a pseudoautosomal gene. XE7 had been identified in a large-scale proteomic analysis of the human spliceosome. It consists of two different isoforms produced by alternative splicing. The arginine/serine (RS)-rich region in the larger of these suggests a role in mRNA processing. Herein we show for the first time that XE7 is an alternative splicing regulator. XE7 interacts with ZNF265, as well as with the essential SR protein ASF/SF2. The RS-rich region of XE7 dictates both interactions. We show that XE7 localizes in the nucleus of human cells, where it colocalizes with both ZNF265 and ASF/SF2, as well as with other SR proteins, in speckles. We also demonstrate that XE7 influences alternative splice site selection of pre-mRNAs from CD44, Tra2-beta1 and SRp20 minigenes. We have thus shown that the spliceosomal component XE7 resembles an SR-related splicing protein, and can influence alternative splicing.

Alternative Splicing↗
PubMed2006

Renin enhancer is critical for control of renin gene expression and cardiovascular function.

The important cardiovascular regulator renin contains a strong in vitro enhancer 2.7 kb upstream of its gene. Here we tested the in vivo role of the mouse Ren-1c enhancer. In renin-expressing As4.1 cells stably transfected with Ren-1c promoter with or without enhancer, expression of linked beta-geo reporter, stable expression, and colony formation were dependent on the presence of the enhancer. We then generated mice carrying a targeted deletion of the enhancer (REKO mice) and found marked depletion of renin in renal juxtaglomerular and submandibular ductal cells, as well as hyperplasia of macula densa cells. Plasma creatinine was increased, but electrolytes were normal. Male REKO mice implanted with telemetry devices had 9 +/- 1 mm Hg lower mean arterial pressure (p < 0.001), which was partly normalized by a high NaCl diet. Locomotor activity was lower, and baroreflex sensitivity was normal. Markedly reduced mean arterial pressure variability in the midfrequency band indicated a contribution of reduced sympathetic vasomotor tone to the hypotension. In conclusion, the renin enhancer is critical for renin gene expression and physiological sequelae, including response to alteration in salt intake. The REKO mouse may be useful as a low renin expression model.

Animals↗
PubMed2006

WT1 interacts with the splicing protein RBM4 and regulates its ability to modulate alternative splicing in vivo.

Wilm's tumor protein 1 (WT1), a protein implicated in various cancers and developmental disorders, consists of two major isoforms: WT1(-KTS), a transcription factor, and WT1(+KTS), a post-transcriptional regulator that binds to RNA and can interact with splicing components. Here we show that WT1 interacts with the novel splicing regulator RBM4. Each protein was found to colocalize in nuclear speckles and to cosediment with supraspliceosomes in glycerol gradients. RBM4 conferred dose-dependent and cell-specific regulation of alternative splicing of pre-mRNAs transcribed from several reporter genes. We found that overexpressed WT1(+KTS) abrogated this effect of RBM4 on splice-site selection, whereas WT1(-KTS) did not. We conclude that the (+KTS) form of WT1 is able to inhibit the effect of RBM4 on alternative splicing.

Alternative Splicing↗
PubMed2006

Regulation of the neuronal proteasome by Zif268 (Egr1).

Most forms of neuronal plasticity are associated with induction of the transcription factor Zif268 (Egr1/Krox24/NGF-IA). In a genome-wide scan, we obtained evidence for potential modulation of proteasome subunit and regulatory genes by Zif268 in neurons, a finding of significance considering emerging evidence that the proteasome modulates synaptic function. Bioinformatic analysis indicated that the candidate proteasome Zif268 target genes had a rich concentration of putative Zif268 binding sites immediately upstream of the transcriptional start sites. Regulation of the mRNAs encoding the psmb9 (Lmp2) and psme2 (PA28beta) proteasome subunits, along with the proteasome-regulatory kinase serum/glucocorticoid-regulated kinase (SGK) and the proteasome-associated antigen peptide transporter subunit 1 (Tap1), was confirmed after transfection of a neuronal cell line with Zif268. Conversely, these mRNAs were upregulated in cerebral cortex tissue from Zif268 knock-out mice relative to controls, confirming that Zif268 suppresses their expression in the CNS. Transfected Zif268 reduced the activity of psmb9, SGK, and Tap1 promoter-reporter constructs. Altered psmb9, SGK, and Tap1 mRNA levels were also observed in an in vivo model of neuronal plasticity involving Zif268 induction: the effect of haloperidol administration on striatal gene expression. Consistent with these effects on proteasome gene expression, increased Zif268 expression suppressed proteasome activity, whereas Zif268 knock-out mice exhibited elevated cortical proteasome activity. Our findings reveal that Zif268 regulates the expression of proteasome and related genes in neuronal cells and provide new evidence that altered expression of proteasome activity after Zif268 induction may be a key component of long-lasting CNS plasticity.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

Lark is the splicing factor RBM4 and exhibits unique subnuclear localization properties.

Lark is an RNA-binding protein of the RNA recognition motif (RRM) class and, in Drosophila, Lark is required for embryonic development. In attempting to determine the function of human Lark we uncovered a frame-shift error in the published sequence to reveal that Lark is, in fact, RBM4, a recently described splicing regulator. We then went on to show that RBM4 localizes in nuclear speckles and nucleoli, supporting its potential role in splicing or RNA processing. Immunofluorescence imaging of full-length and mutated RBM4 revealed that the C-terminus of RBM4 is crucial for targeting to speckles. Unlike many other splicing factors, however, RBM4 does not contain an RS-domain or any other known targeting site. RBM4 redistributed to perinucleolar clusters upon the addition of a transcription inhibitor, whereas other splicing factors display increased localization to speckles in the absence of transcription. This finding is consistent with the potential existence of a novel subnuclear targeting pathway. In conclusion, RBM4 and Lark are the same protein, are localized in speckles and nucleoli, but can redistribute to perinucleolar clusters, consistent with a novel subnuclear pathway.

Amino Acid Sequence↗
PubMed2006

RACP's policy statement on infant male circumcision is ill-conceived.

OBJECTIVE: To conduct a critical peer-review of the 2004 Policy Statement on routine male circumcision produced by the Royal Australasian College of Physicians (RACP). METHOD: Comprehensive evaluation in the context of the research field. RESULTS: We find that the current Statement downplays the wide-ranging life-long benefits of circumcision in prevention of urinary tract infections (UTIs), penile and cervical cancer, genital herpes and chlamydia in women, HIV infection, phimosis, and various penile dermatoses, and at the same time overstates the complication rate. We highlight the many errors in the RACP Statement and note that it sidesteps making a conclusion based on circumcision's well-documented prophylactic health benefits by instead referring to the status of the foreskin at birth. In the era of preventative medicine we view this as irresponsible. CONCLUSION: The RACP's Statement on routine male circumcision is not evidence-based and should be retracted. IMPLICATIONS: In the interests of public health and individual well-being an extensive, comprehensive, evidence-based revision should be conducted so as to provide scientifically accurate, balanced information on the advantages, and also the low rate of mostly minor complications, associated with this simple procedure, which for maximum benefits and minimal risk should ideally be performed in the neonatal period.

Australia↗
PubMed2005

Chronic phencyclidine administration induces schizophrenia-like changes in N-acetylaspartate and N-acetylaspartylglutamate in rat brain.

Administration of phencyclidine (PCP) to both humans and animals models the symptoms of schizophrenia. Brain concentrations of N-acetylaspartate (NAA) are reduced in this disease, reflecting neuronal dysfunction. This study investigates the effects in rats of a chronic intermittent regime of PCP on NAA and its precursor N-acetylaspartylglutamate (NAAG) in rat frontal and temporal cortex, hippocampus and striatum, determined by HPLC. We found significant PCP-induced deficits of NAA and NAAG only in the temporal cortex; NAAG was significantly elevated in the hippocampus. These changes closely reflect postmortem findings reported in schizophrenia.

Animals↗
PubMed2005

Impairment in perceptual attentional set-shifting following PCP administration: a rodent model of set-shifting deficits in schizophrenia.

RATIONALE: Impaired ability to shift perceptual attentional set forms a core feature of schizophrenic illness and is associated with prefrontal cortical dysfunction. A pharmacological model producing equivalent deficits in rodents may enable the development of novel therapeutic strategies for effective treatment of cognitive impairments in schizophrenia. OBJECTIVE: This study was designed to investigate the effects of phencyclidine (PCP) administration on performance in a rodent attentional set-shifting task and the neural correlates of PCP-induced deficits in task performance. METHODS: Twenty-four hours following acute administration of 2.58 mg/kg PCP or vehicle, rats were tested on a perceptual attentional set shifting task (Birrell and Brown in J Neurosci 20:4320-4324, 2000). Following completion of the task, in situ hybridisation was employed to detect concurrent regional alterations in zif-268 and parvalbumin mRNA expression. RESULTS: PCP administration selectively decreased the ability of rats to shift attentional set between perceptual dimensions (extra-dimensional shift, EDS). This impairment was accompanied by, and correlated with, decreases in expression of zif-286 in the infralimbic cortex and of parvalbumin in the dorsal reticular nucleus of the thalamus. CONCLUSION: Acute administration of PCP produces deficits in perceptual set shifting comparable to an aspect of executive dysfunction in schizophrenia. Moreover, this impairment is associated with altered medial prefrontal cortical and reticular thalamic activity. Therefore, this rodent paradigm may model the set-shifting deficits that form a core feature of schizophrenic pathology.

Animals↗
PubMed2005

Genome-wide scan for hypertension in Sydney Sibships: the GENIHUSS study.

We report here the results of the GENIHUSS study (GENetic Investigation of Hypertension Undertaken in Sydney Sibships)-a genome-wide scan to identify loci linked to essential hypertension (HT). Subjects were Anglo-Celtic Australian sibpairs resident in or near Sydney, Australia, with onset of HT before age 60 years (mean, 44 +/- 13 SD years). A 10-cM scan involving 400 microsatellite markers and 252 HT sibpairs was followed by fine mapping of the most promising locus using 296 HT sibpairs (481 individuals from 200 families). Multipoint and two-point nonparametric linkage analyses were performed using MAPMAKER/SIBS, GENEHUNTER II, and SPLINK. Suggestive loci were found on chromosomes 1 (4 cM) and 4 (129 cM). The chromosome 4 locus coincided with a QTL for systolic blood pressure (BP) in the Australian Victorian Family Heart Study, and the locus on chromosome 1 contains the chloride channel gene CLCNKB and tumor necrosis factor receptor 2 gene TNFRSF1B, which have each shown association with HT. Our study adds to findings of HT loci emanating from genome scans.

Adult↗
PubMed2005

PCP: from pharmacology to modelling schizophrenia.

Phencyclidine has attracted the attention of neuroscientists for many years because of its ability to produce, in humans, a range of symptoms remarkably similar to those of patients suffering from schizophrenia. The main action of phencyclidine is as a non-competitive antagonist of the NMDA class of glutamate receptor. In the past few years, dramatic advances have been made in our understanding of the neuroanatomical and pathological basis of schizophrenia. In turn, these have allowed assessment of the ability of phencyclidine to produce equivalent changes in the rodent CNS. It has now become clear that chronic intermittent low doses of phencyclidine produce a pattern of metabolic and neurochemical changes in the rodent brain that mirror those observed in the brains of schizophrenic patients with impressive precision. This should be of enormous benefit in the search for new anti-psychotic drugs with improved efficacy against the full range of schizophrenic symptoms.

Animals↗
PubMed2005

A forkhead in the road to longevity: the molecular basis of lifespan becomes clearer.

OBJECTIVE: Although the quest for longevity is as old as civilization itself, only recently have technical and conceptual advances in genomics research brought us to the point of understanding the precise molecular events that make us age. This heralds an era when manipulations of these will enable us to live longer, healthier lives. The present review describes how recent experimental strategies have identified key genes and intracellular pathways that are responsible for ageing and longevity. FINDINGS: In diverse species transcription factors belonging to the forkhead/winged helix box gene, group O (FOXO) subfamily have been found to be crucial in downstream suppression of the life-shortening effects of insulin/insulin-like growth factor-I receptor signalling pathways that, when upregulated, accelerate ageing by suppression of FOXO. The various adverse processes activated upon FOXO suppression include increased generation of reactive oxygen species (ROS). ROS are pivotal for the onset of various common conditions, including hypertension, atherosclerosis, type 2 diabetes, cancer and Alzheimer's disease, each of which shortens lifespan. In humans, FOXO3a, as well as FOXO1 and -4, and their downstream effectors, could hold the key to counteracting ageing and common diseases. An understanding of the processes controlled by these FOXOs should permit development of novel classes of agents that will more directly counteract or prevent the damage associated with diverse life-threatening conditions, and so foster a life of good health to a ripe old age. Just like caloric restriction, lifespan can be increased in various species by plant-derived polyphenols, such as resveratrol, via activation of sirtuins in cells. Sirtuins, such as SIRT1 in mammals, utilize FOXO and other pathways to achieve their beneficial effects on health and lifespan. CONCLUSION: Lifespan is tractable and basic mechanisms are now known. Longevity research complements and overlaps research in most major medical disciplines. Current progress bodes well for an ever-increasing length of healthy life for those who adapt emerging knowledge personally (so-called 'longevitarians').

Aging↗
PubMed2005

No association with hypertension of CLCNKB and TNFRSF1B polymorphisms at a hypertension locus on chromosome 1p36.

OBJECTIVE: Chromosome 1p36 has been linked to essential hypertension and systolic blood pressure. This locus contains the chloride channel-Kb gene (CLCNKB) and the tumour necrosis factor receptor 2 gene (TNFRSF1B). Polymorphisms of each of these have shown association with hypertension, and a CLCNKB T481S variant alters receptor function. Here we performed association studies in a well-characterized cohort of hypertensives and normotensives whose blood pressure status matched that of both their parents. METHODS: The study involved 196 essential hypertensives and 321 normotensives. These were genotyped for TNFRSF1B variants T-1710A upstream, A257G in exon 2, a CA-repeat polymorphism in intron 4, E232K and M196R in exon 6, and T1668G and T1690C in the 3'-untranslated region, and the T481S variant of CLCNKB. RESULTS: The CLCNKB T481S variant showed no association with hypertension. Thermodynamic modelling of the 3'-untranslated region of TNFRSF1B mRNA predicted that the T1668G variant alters the stem-loop structure and thus the mRNA stability and expression. However, neither this nor the other TNFRSF1B polymorphisms, either alone or after haplotype analysis, were associated with hypertension. Moreover, for each gene the blood pressure, body mass index, plasma sodium and plasma lipid concentrations were generally similar across genotypes. CONCLUSION: Our data fail to support previous association findings for TNFRSF1B and CLCNKB at the chromosome 1p36 locus implicated in hypertension.

3' Untranslated Regions↗