Brn-3b enhances the pro-apoptotic effects of p53 but not its induction of cell cycle arrest by cooperating in trans-activation of bax expression.

The Brn-3a and Brn-3b transcription factor have opposite and antagonistic effects in neuroblastoma cells since Brn-3a is associated with differentiation whilst Brn-3b enhances proliferation in these cells. In this study, we demonstrate that like Brn-3a, Brn-3b physically interacts with p53. However, whereas Brn-3a repressed p53 mediated Bax expression but cooperated with p53 to increase p21cip1/waf1, this study demonstrated that co-expression of Brn-3b with p53 increases trans-activation of Bax promoter but not p21cip1/waf1.

Distinct domains of Brn-3a regulate apoptosis and neurite outgrowth in vivo.

The Brn-3a transcription factor is critical for the normal development of the nervous system, promoting both neuronal survival and neurite outgrowth. By manipulating the Brn-3a gene in intact mice, we show that these two functions are separately controlled with an N-terminal domain being essential for neuronal survival, whereas the POU domain is essential for neurite outgrowth. Hence the two naturally occurring forms of Brn-3a, which either contain or lack the N-terminal domain, are likely to play distinct roles in the nervous system.

Cold-sensitive, menthol-insensitive neurons in the murine sympathetic nervous system.

Several mechanisms have been implicated in underlying the perception of cold, most notably the activation of TRPM8 and TRPA1. We have used ratiometric calcium imaging to reveal a population of neurons in the superior cervical ganglion (SCG) of the mouse that respond to cooling but are insensitive to menthol. Furthermore we show that the expression of the mRNA transcripts encoding the recently identified noxious cold-sensitive channel TRPA1 but not TRPM8 are expressed in the SCG.

Doppel expression is regulated by the Brn-3a and Brn-3b transcription factors.

Doppel and the prion protein (PrP) are two related proteins involved in different aspects of neuronal degeneration. While a structural modification of PrP is necessary and sufficient for its toxic effect, the neurotoxicity of Doppel in the Purkinje cells of the cerebellum relies solely on its overexpression. Understanding the Doppel-related neurotoxicity thus involves the analysis of its developmental and transcriptional regulation.

Sensory neurons from mice lacking the Brn-3b POU family transcription factor are resistant to death-inducing stimuli both in vitro and in vivo.

The critical role for programmed cell death in the normal development of the nervous system and the abnormal cell death that occurs in human neurodegenerative diseases renders it of vital importance to identify factors that enhance or reduce the levels of cell death in specific neuronal cells in the nervous system. We show that the Brn-3b transcription factor is essential for normal cell death responses in the peripheral nervous system and that in its absence neurons are resistant to a variety of death-inducing stimuli both in vitro and in vivo.

The POU domain transcription factor Brn-3a protects cortical neurons from apoptosis.

We have demonstrated previously that exogenously expressed Brn-3a is capable of protecting neurons of the peripheral nervous system against apoptosis. In these previous studies Brn-3a showed a degree of neuronal sub-type specificity, in that while it could promote survival in NGF-dependent sensory neurons, no effect was observed in NGF-dependent neurons of the sympathetic nervous system. In this report, we show that Brn-3a delivered using a herpes simplex virus is capable of protecting cultures of rat cerebrocortical neurons of the central nervous system against two types of cell death stimuli, including glutamate neurotoxicity.

Brn-3a activates the expression of Bcl-x(L) and promotes neuronal survival in vivo as well as in vitro.

The determination of cell fate plays a critical role during the later stages of embryogenesis and the early postnatal period-a time during which approximately half of neurons born during neurogenesis undergo programmed cell death. It has previously been reported that the type IV POU domain transcription factor Brn-3a plays a role in the maturation and survival of sensory neuronal populations. Indeed we have shown that the long form of Brn-3a is capable of activating expression of the antiapoptotic Bcl-2 gene and enhancing neuronal survival in cultures of sensory neurons.

The BRN-3A transcription factor protects sensory but not sympathetic neurons from programmed cell death/apoptosis.

Inactivation of the gene encoding the POU domain transcription factor BRN-3A results in the absence of specific neurons in knockout mice. Here we demonstrate for the first time a direct effect of BRN-3A on the survival of neuronal cells. Specifically, overexpression of BRN-3A in cultured trigeminal ganglion or dorsal root ganglion sensory neurons enhanced their survival following the withdrawal of nerve growth factor.

Regulation of NGFI-A (Egr-1) gene expression by the POU domain transcription factor Brn-3a.

NGFI-A is an immediate early gene (IEG) that is transcriptionally induced by nerve growth factor (NGF) in PC12 cells and has been implicated in a number of cellular responses. Studies have shown that elements within the first 106 base pairs of the NGFI-A promoter contribute to its induction by NGF in PC12 cells. One element, within the serum response element (SRE) bridge region, bears strong homology to a motif previously identified in promoters regulated by the Brn-3a POU domain transcription factor.

Bcl-2 transcription from the proximal P2 promoter is activated in neuronal cells by the Brn-3a POU family transcription factor.

The BCL-2 protein is able to protect neuronal and other cell types from apoptotic programmed cell death and plays a key role in regulating the rate of apoptosis during development of the nervous system. We have previously demonstrated that the Brn-3a POU domain transcription factor protects sensory neurons from apoptotic programmed cell death induced by nerve growth factor withdrawal. We report here that Bcl-2 transcription is predominantly initiated from the Bcl-2 P2 promoter in both the ND7 neuronal cell line and primary dorsal root ganglion neurons, in contrast to the predominant use of the Bcl-2 P1 promoter in other cell types.

Activation of the gene encoding decay accelerating factor following nerve growth factor treatment of sensory neurons is mediated by promoter sequences within 206 bases of the transcriptional start site.

Using two independent differential screening procedures designed to identify novel mRNAs induced by nerve growth factor (NGF) treatment of adult dorsal root ganglion (DRG) neurons, we have isolated cDNA clones derived from the gene encoding decay accelerating factor (DAF). Hybridization analysis and semi-quantitative polymerase chain reaction confirmed that the DAF mRNA was indeed induced in NGF-treated adult DRG neurons. Moreover, the DAF gene promoter is NGF inducible (approximately two- to threefold) when transfected into DRG neurons, and this effect is primarily dependent on sequences between -206 and -77 relative to the transcriptional start site.

Nerve growth factor treatment of sensory neuron primary cultures causes elevated levels of the mRNA encoding the ATP synthase beta-subunit as detected by a novel PCR-based differential cloning method.

The mRNA encoding the rat ATP synthase beta-subunit was rapidly induced by nerve growth factor, within 60 min, in cultured adult rat dorsal root ganglion neurons. ATP synthase beta-subunit cDNA clones were isolated from a lambda library. The library was constructed using rat dorsal root ganglion mRNA that was differentially screened with cDNA-derived probes from untreated and nerve-growth-factor-treated primary cultures of adult rat dorsal root ganglion sensory neurons.

Induction of the Oct-2 transcription factor in primary sensory neurons during inflammation is nerve growth factor-dependent.

The mRNA encoding the POU family transcription factor Oct-2 is induced in cultured adult sensory neurons following treatment with nerve growth factor (NGF) but not with a variety of other growth factors. We show here that the Oct-2 mRNA is also upregulated in vivo in sensory neurons innervating inflamed tissue following intraplantar injection of complete Freund's adjuvant. This rise is abolished by systemic administration of anti-NGF neutralizing antibodies indicating that it is an NGF-dependent effect.

Is Burkholderia (Pseudomonas) cepacia disseminated from cystic fibrosis patients during physiotherapy?

Burkholderia cepacia is well recognized as a potential respiratory pathogen in cystic fibrosis (CF) patients and there is increasing concern about nosocomial acquisition. Environmental contamination with B. cepacia before, during and after physiotherapy was studied in eight adult CF patients.

A minimal CGRP gene promoter is inducible by nerve growth factor in adult rat dorsal root ganglion neurons but not in PC12 phaeochromocytoma cells.

The calcitonin/CGRP gene is transcribed in thyroid C cells and some neuronal cells but not in other cell types. Although the promoter sequences mediating gene activity in thyroid C cells have been extensively studied, the elements responsible for promoter activity in neuronal cells and its stimulation by nerve growth factor (NGF) have not previously been defined. We report the first use of the calcium phosphate procedure to successfully transfect adult rat dorsal root ganglion neurons, which naturally express the calcitonin/calcitonin gene-related peptide (CGRP) in an NGF-inducible manner.

Nerve growth factor induces the Oct-2 transcription factor in sensory neurons with the kinetics of an immediate-early gene.

The Oct-2 transcription factor has a predominantly inhibitory effect on gene expression in neuronal cell lines. This factor and its corresponding mRNA have previously been shown to be elevated in adult rat dorsal root ganglion (DRG) neurons chronically exposed to nerve growth factor (NGF). Here we show that the Oct-2 mRNA is rapidly induced in DRG cells exposed to NGF and that such induction still occurs to a lesser extent in the presence of the protein synthesis inhibitor cycloheximide.

Nerve growth factor induces expression of immediate-early genes NGFI-A (Egr-1) and NGFI-B (nur 77) in adult rat dorsal root ganglion neurons.

We have used primary cultures of adult rat dorsal root ganglia (DRG), enriched in sensory neurons, to investigate the induction of immediate-early genes by NGF and a variety of other growth factors. Using the polymerase chain reaction we have quantitatively amplified specific mRNA transcripts induced by NGF, in the presence and absence of the protein synthesis inhibitor cycloheximide. NGFIA (Egr-1) and NGFIB (nur 77) mRNAs were elevated in level within 60 min of NGF treatment and independently of de novo protein synthesis.