The isolation and characterization of the promoter of the human type 1 inositol 1,4,5-trisphosphate receptor

In humans, at least three types of inositol (1,4,5)-trisphosphate receptor (IP3R) are present. The gene encoding type 1 IP3R (IP3R-I) is expressed in all cell types, although expression predominates in Purkinje cells. To study the regulation of the human IP3R-I gene, we isolated and characterized a 2.1-kb 5' flanking region. In transient expression assays using a rat cell line, analysis of various deletion mutants demonstrated that a fragment of only 86 bp 5' of the putative tsp displayed a promoter activity similar to that of the 2.1-kb fragment. Also, we compared the sequence of the human IP3R-T promoter with the sequence of the mouse IP3R-I promoter. Considerable sequence homology is present in four distinct domains, which include several conserved putative binding sites for transcription factors. Further, we demonstrate a decrease in the activity of the isolated human IP3R-I promoter and of the endogenous IP3R-I promoter after 48 h of treatment with retinoic acid. Analysis of deletion constructs of the human promoter indicates that the decreased promoter activity in response to retinoic acid is likely to be mediated by a conserved AP-2 binding site. (C) 1998 Elsevier Science B.V

LOCALIZATION OF TRANSCRIPTS OF THE RELATED NUCLEAR ORPHAN RECEPTORS COUP-TF-I AND ARP-1 IN THE ADULT-MOUSE BRAIN

The chicken ovalbumin upstream promoter transcription factor, COUP-TF I, and the protein ARP-1 (COUP-TF II) are two highly homologous orphan receptors of the nuclear hormone receptor family. In this study we investigated their expression patterns in the adult nervous system of the mouse. In situ hybridizations were performed on brain sections with S-35-labeled cRNA probes derived from the 3'-non-coding regions of the mARP-1 and mCOUP-TF I mRNAs. Both COUP-TF I and ARP-1 were shown to be expressed in the adult brain and they displayed restricted and distinct expression patterns. COUP-TF I transcripts were predominantly found in the rostral and caudal parts of the adult mouse brain, whereas ARP-I transcripts prevaled in the middle part of the brain. High expression of COUP-TF I was detected in the olfactory nucleus, in neocortex layers I/II and V/VI, in the dentate gyrus and in areas CA1/CA3/CA4 of the hippocampus, and in the granular layer of the cerebellum. Only low amounts of COUP-TF I mRNA were detected in the ventral, the laterodorsal and in the interanteromedial thalamic nuclei. Small amounts of COUP-TF I transcripts were also found in the epithelial layer of the ventricle and in arachnoid membranes. High expression of ARP-I was detected in the reticular, the ventral lateral and the gelatinosus thalamic nuclei. Other hot spots of ARP-1 mRNA expression were the amygdaloid nucleus and the arachnoid membranes. Lower amounts of ARP-1 transcripts were found in the anterior and lateral hypothalamic areas, in the suprachiasmatic nucleus, and in the choroid plexus. Overlapping expression of COUP-TF I and ARP-1 mRNA was only found in the ventral lateral thalamic nucleus. These expression patterns do not coincide with a particular neuronal phenotype. The distinct distributions suggest different functional roles for each of the corresponding gene products in the mature nervous system

A dual function for p38 MAP kinase in hematopoietic cells: involvement in apoptosis and cell activation

In the present study we examined in more detail the dual role of the c-JUN N-terminal kinase (JNK) and p38 stress-activated protein kinase pathways in mediating apoptosis or cellular activation in hematopoietic cells. Growth factor deprivation of the erythroleukemic cell line TF-1 led to apoptosis which was associated with an enhanced activity of JNK and p38 and immediate dephosphorylation of the extracellular signal-regulated kinases (ERKs). Enhanced activity of p38 and JNK was not only observed during apoptosis but also in TF-1 cells stimulated with IL-1. IL-1 rescued TF-1 cells from apoptosis. In this case, the upregulation of p38 and JNK was associated with an enhanced activity of ERK. By using SB203580, a specific inhibitor of the p38 signaling pathway, it was demonstrated that p38 plays a pivotal role in the apoptotic process. SB203580 repressed the apoptotic process to a large extent. In contrast, PD98059, a specific inhibitor of the ERK pathway, counteracted the suppressive effects of SB203580 and IL-1 on the apoptotic process indicating that the protective effect of SB203580 and IL-1 might be the result of a shift in the balance between the ERK1/2 and p38/JNK route. This was also supported by experiments with TF-1 cells overexpressing the Shc protein that demonstrated a significantly lower percentage of apoptotic cells, which coincided with higher ERK activity. Finally, the IL-1 and SB203580-mediated effects were associated with an enhanced nuclear factor-kappa B (NF-kappa B) and activator protein-1 (AP-1) binding activity, which could also be blocked by PD98059. These data demonstrate a dual function of the p38 pathway whereby other factors, such as ERK kinases, AP-1 and NF-kappa B, might determine the final cellular response