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Biomedical subjects

Victoria Heath

Publications and source records attributed to Victoria Heath.

6 recordsLinked to original sources
PubMed2006

CAAT/enhancer-binding protein delta and cAMP-response element-binding protein mediate inducible expression of the nerve growth factor gene in the central nervous system.

Nerve growth factor (NGF) synthesis in the rat cerebral cortex is induced by the beta2-adrenergic receptor agonist clenbuterol (CLE). Because NGF is a crucial neurotrophic factor for basal forebrain cholinergic neurons, defining the mechanisms that regulate its transcription is important for developing therapeutic strategies to treat pathologies of these neurons. We previously showed that the transcription factor CCAAT/enhancer-binding protein delta (C/EBPdelta) contributes to NGF gene regulation. Here we have further defined the function of C/EBPdelta and identified a role for cAMP response element-binding protein (CREB) in NGF transcription. Inhibition of protein kinase A in C6-2B glioma cells suppressed CLE induction of an NGF promoter-reporter construct, whereas overexpression of protein kinase A increased NGF promoter activity, particularly in combination with C/EBPdelta. A CRE-like site that binds CREB was identified in the proximal NGF promoter, and C/EBPdelta and CREB were found to associate with the NGF promoter in vivo. Deletion of the CRE and/or C/EBP sites reduced CLE responsiveness of the promoter. In addition, ectopic expression of C/EBPdelta in combination with CLE treatment increased endogenous NGF mRNA levels in C6-2B cells. C/EBPdelta null mice showed complete loss of NGF induction in the cerebral cortex following CLE treatment, demonstrating a critical role for C/EBPdelta in regulating beta2-adrenergic receptor-mediated NGF expression in vivo. Thus, our findings demonstrate a critical role for C/EBPdelta in regional expression of NGF in the brain and implicate CREB in CLE-induced NGF gene transcription.

Adrenergic beta-Agonists↗
PubMed2004

C/EBPalpha deficiency results in hyperproliferation of hematopoietic progenitor cells and disrupts macrophage development in vitro and in vivo.

CCAAT enhancer binding protein-alpha (C/EBPalpha) inhibits proliferation in multiple cell types; therefore, we evaluated whether C/EBPalpha-deficient hematopoietic progenitor cells (HPCs) have an increased proliferative potential in vitro and in vivo. In this study we demonstrate that C/EBPalpha(-/-) fetal liver (FL) progenitors are hyperproliferative, show decreased differentiation potential, and show increased self-renewal capacity in response to hematopoietic growth factors (HGFs). There are fewer committed bipotential progenitors in C/EBPalpha(-/-) FL, whereas multipotential progenitors are unaffected. HGF-dependent progenitor cell lines can be derived by directly culturing C/EBPalpha(-/-) FL cells in vitro Hyperproliferative spleen colonies and myelodysplastic syndrome (MDS) are observed in mice reconstituted with C/EBPalpha(-/-) FL cells, indicating progenitor hyperproliferation in vitro and in vivo. C/EBPalpha(-/-) FL lacked macrophage progenitors in vitro and had impaired ability to generate macrophages in vivo. These findings show that C/EBPalpha deficiency results in hyperproliferation of HPCs and a block in the ability of multipotential progenitors to differentiate into bipotential granulocyte/macrophage progenitors and their progeny.

Animals↗
PubMed2003

p53 polymorphism influences response in cancer chemotherapy via modulation of p73-dependent apoptosis.

Intact p73 function is shown to be an important determinant of cellular sensitivity to anticancer agents. Inhibition of p73 function by dominant-negative proteins or by mutant p53 abrogates apoptosis and cytotoxicity induced by these agents. A polymorphism encoding either arginine (72R) or proline (72P) at codon 72 of p53 influences inhibition of p73 by a range of p53 mutants identified in squamous cancers. Clinical response following cisplatin-based chemo-radiotherapy for advanced head and neck cancer is influenced by this polymorphism, cancers expressing 72R mutants having lower response rates than those expressing 72P mutants. Polymorphism in p53 may influence individual responsiveness to cancer therapy.

Adult↗
PubMed2002

Epigenetic inactivation of 14-3-3 sigma in oral carcinoma: association with p16(INK4a) silencing and human papillomavirus negativity.

In vitro studies have identified 14-3-3sigma as a regulator of senescence in human keratinocytes. To assess its contribution to squamous neoplasia, we have analyzed genetic and epigenetic changes in this gene in squamous cell carcinomas (SCCs) and dysplastic lesions of the oral cavity. No mutations were detected in the coding sequence of 14-3-3sigma in 20 oral carcinomas, and there was loss of heterozygosity in only 7 of 40 informative cases. In contrast to the absence of genetic change, aberrant methylation within 14-3-3sigma was detected in 32 of 92 squamous cell carcinomas and in 3 of 6 oral dysplasias and was associated with reduced or absent expression at both mRNA and protein levels. Methylation was not detected in matched, normal epithelial tissue controls. Carcinomas in which 14-3-3sigma was methylated were significantly more likely to lack DNA sequences from human papillomavirus and to have coincident methylation of p16(INK4a) than cases that expressed 14-3-3sigma. Methylation was detected in SCC, both wild-type and mutant for p53, but was more commonly detected in cancers with wild-type p53. These results implicate coincident epigenetic abrogation of function in both sigma and p16(INK4a) in a subset of SCCs of the oral cavity.

14-3-3 Proteins↗
PubMed2002

Increased fetal nuchal translucency at 11-14 weeks.

Nuchal translucency (NT) is the sonographic appearance of a subcutaneous collection of fluid behind the fetal neck. The measurement of fetal NT thickness at the 11-14-week scan has been combined with maternal age to provide an effective method of screening for trisomy 21; for an invasive testing rate of 5%, about 75% of trisomic pregnancies can be identified. When maternal serum free-beta human chorionic gonadotrophin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11-14 weeks are also taken into account, the detection rate of chromosomal defects is about 90%. Increased NT can also identify a high proportion of other chromosomal abnormalities and is associated with major defects of the heart and great arteries, and a wide range of skeletal dysplasias and genetic syndromes. In monochorionic twins, discordancy for increased NT is an early marker of twin-to-twin transfusion syndrome (TTTS). As with the introduction of any new technology into routine clinical practice, it is essential that those undertaking the 11-14-week scan are adequately trained and their results are subjected to rigorous audit.

Biomarkers↗