Three distinct regions within the constitutive activation domain of cAMP regulatory element-binding protein (CREB) are required for transcription activation

The transcription factor cAMP regulatory element-binding protein (CREB) mediates both constitutive and cAMP-induced gene expression through distinct, independently acting domains. The constitutive activation domain (CAD) (amino acids (aa) 165-252) encompasses and overlaps exon 9 of the CREB gene (E9, aa 180-243). In the present study, deletion of either the CAD or exon 9 from CREB-GAL4 (CRG) reduced constitutive activity to less than 2-fold, without affecting kinase inducible activity. However, fusion of the CAD to the GAL4 DNA binding domain (CAD-G4) stimulated transcription, whereas fusion of exon 9 sequences did not. Deletion of the amino-terminal flanking region of exon 9 (aa 165-180), but not COOH-terminal flanking sequences (aa 243-252), decreased constitutive activation in either the CAD-G4 or CRG background. Deletion of the previously characterized glutamine-rich region (Q3, aa 218-252) or of a region containing a hydrophobic cluster of amino acids (HC, aa 180-218) also reduced constitutive activation by either CAD-G4 or CRG. No single mutation of hydrophobic residues within HC impaired activity of the CAD, but double and triple mutations did, suggesting that multiple weak interactions are involved in function of the HC region. Thus, exon 9 of the CREB gene is necessary but not sufficient for constitutive activation. The CAD requires three distinct regions for function, suggesting that CREB may interact with multiple targets in the RNA polymerase II complex.

The endoplasmic reticular heat shock protein gp96 is transcriptionally upregulated in interferon-treated cells

A cDNA clone complementary to an interferon (IFN)-induced mRNA approximately 3 kb in length was identified and sequenced revealing homology with the endoplasmic reticular heat shock protein/ATPase gp96. Both IFN-alpha and -gamma transcriptionally upregulate expression of this gene. gp96 transcripts, protein, and ATPase activity are shown to be enhanced as a result of IFN treatment in two human cell lines and this effect requires de novo protein synthesis. gp96 molecules have recently been implicated in the presentation of endogenous antigens. A number of the key elements in this pathway, the transporter proteins, the major histocompatibility complex (MHC)-linked units of the proteasomes and the MHC class I molecules are known to be IFN inducible. Our results show that yet another molecule suggested to play an accessory role in the endogenous presentation pathway is IFN inducible. Further, our studies represent the first demonstration of modulation of expression of a heat shock protein by a cytokine and identify a new enzymatic activity upregulated in IFN-treated cells.

[Immunological observation on chyluric patients with heat-clearing and hemostatic drugs]

In order to investigate the pathogenesis and therapeutic mechanism of chyluria, an experiment with a basic Heat-clearing and hemostatic prescription was conducted in treating 30 patients of chyluria. The result, 26 cases were cured completely. The cell-mediated and humoral immunity observation showed that OKT3 and OKT4 levels were commonly low in chyluric cases, and OKT8 as higher than normal value, the OKT4/OKT8 ratio was inverted before treatment. While OKT3 and OKT4 increased commonly, and OKT8 decreased with the OKT4/OKT8 ratio adjusted after treatment. Meanwhile, humoral immunity level was also commonly low before treatment, it increased after treatment.

Suppression of mitochondrial mRNA levels and mitochondrial function in cells responding to the anticellular action of interferon

A lambda cDNA library prepared from polyadenylated RNA isolated from Daudi cells was differentially screened to isolate cDNAs that recognize mRNA whose levels are reduced following interferon (IFN) treatment. Southern blot and DNA sequence analysis of 20 cDNA clones that were isolated revealed that they represented mitochondrially encoded mRNAs for the following proteins: cytochrome c oxidase subunits II and III, ATPase 6, cytochrome b, and subunit 1 of the NADH dehydrogenase. Northern blot analysis employing these cDNAs and oligonucleotides generated to the remaining mitochondrially encoded mRNAs demonstrated that IFN-alpha treatment of Daudi cells mediates a time-dependent suppression of the level of all of the mitochondrially encoded mRNAs. Study of this IFN-mediated effect reveals that: (i) the suppression of the level of these mRNAs is dependent on protein synthesis, (ii) it can be observed to occur prior to any detectable effect on thymidine incorporation, (iii) the degree of suppression correlates with the sensitivity of the cells to the anticellular action of IFN, and (iv) the suppression of the level of these RNAs appears to result from an effect on the level of transcription rather than on the stability of these mRNAs. A study of the level of cellular respiration in IFN-treated Daudi cells reveals a clear suppression 3 h following IFN treatment.

Involvement of 3',5'-cyclic adenosine monophosphate regulatory element binding protein (CREB) in both basal and hormone-mediated expression of the phosphoenolpyruvate carboxykinase (PEPCK) gene

Transcription of the phosphoenolpyruvate carboxykinase (PEPCK) and PEPCK-chloramphenicol acetyltransferase (CAT) genes is induced by cAMP and glucocorticoids and is inhibited by insulin in H4IIE cells, as it is in liver. In contrast, PEPCK-CAT expression in HepG2 cells is not affected by insulin but is induced by cAMP, which in turn is repressed by glucocorticoids. Mutations were introduced into well defined transcription factor binding sites to investigate possible interactions between the cAMP regulatory element (CRE) binding protein (CREB) and glucocorticoid response unit (GRU) binding proteins. H4IIE rat hepatoma cells were transfected with PEPCK-CAT plasmids with or without an expression vector for protein kinase A (PKA). Glucocorticoid-induced CAT activity was dependent upon the GRU and was decreased in plasmids lacking the CRE. To determine the direct effects of CREB, the DNA binding and dimerization domain of GAL4 was substituted for that of CREB (CRG), and the PEPCK CRE was replaced with a GAL4 binding site (G4PEPCK-CAT). CRG elevated basal and glucocorticoid-induced activities of G4PEPCK-CAT equally and restored responsiveness to PKA. The basal activity of CRG was not diminished by concomitant treatment with PKA plus its inhibitor peptide, PKI, or by mutation of the PKA phosphorylation. Deletion of C-terminal regions of the CREB activation domain from CRG diminished basal activation without affecting induction by PKA. The glucocorticoid-induced level of CAT activity decreased in proportion to the reduced ability of CREB to activate basal transcription. Induction by glucocorticoid, in the absence or presence of PKA, was not affected by CRG, indicating that interaction of GRU-bound factors with CREB is not required for glucocorticoid induction of PEPCK. These results indicate that CREB is directly involved in basal and PKA-induced expression of PEPCK, and that CREB supports glucocorticoid-induced PEPCK expression through its positive effect on basal transcription.

[Electron microscopy observation on pre- and post-treatment skin of dorsum pedis of chyluric patient treated with heat-clearing and hemostatic drugs--the lymphangial wall damage being the pathogenesis of chyluria]

Heat-clearing and hemostatic drugs were effective in treating chyluria. In order to explore the curative mechanism, a group of 10 in-patients with chyluria were chosen and treated with heat-clearing and hemostatic drugs for 45 days. Some pre- and post-treatment skin from dorsum pedis of the patients were taken off and observed under electron microscope. It showed that the walls of lymphatic capillaries were seriously damaged before treatment and rehabilitated wall after treatment. The pinocytotic vesicles were packed tightly in the endothelial cells of capillaries before treatment and their number was decreased remarkably after treatment; the mast cells were rare in number and abnormal as spindle shape before treatment and they increased in number and became round or oval in shape, the nucleus became large, the granules they contained became more in number and larger in size after treatment, lymph edema was noticed before treatment and it disappeared after treatment. The result showed that the extensive lesion of lymphangial walls is the pathogenesis of chyluria, while the rehabilitation of them is the curative mechanism. It seems that in the process of rehabilitation the mast cells act took the role of "soldier-engineer".

Dietary trace elements and esophageal cancer mortality in Shanxi, China

To explore the relation between esophageal cancer and dietary trace elements in humans, we estimated the average daily intake of zinc, copper, iron, selenium, molybdenum, silicon, cadmium, and nickel in 21 Chinese communes, where the annual mortality rate from esophageal cancer among the population 30 years of age and over ranged from 0 to 495/100,000 person-years. We also estimated the relative level of calcium consumption. Zinc and copper intake were inversely related to esophageal cancer mortality, and calcium intake levels was positively related to esophageal cancer mortality. The predicted esophageal cancer mortality among a vegetarian population with a high level of dietary calcium and a low level of dietary zinc was 5.3 times as high as that in a vegetarian population with a low level of dietary calcium and a high level of dietary zinc. The influence of a high level of dietary calcium in a vegetarian population may be explained by a reduction in the absorption of dietary zinc.

Interferon induces tryptophanyl-tRNA synthetase expression in human fibroblasts

A cDNA clone complementary to an interferon (IFN)-induced mRNA was isolated and used to characterize the regulation of expression of its RNA by the IFNs and to identify the protein its RNA encodes. This cDNA hybridizes to IFN-induced 3.1- and 2.3-kilobase mRNAs that are synthesized in response to both IFN-alpha and IFN-gamma. IFN-gamma induces the sustained accumulation of these mRNAs while IFN-alpha induces their transient accumulation. Cycloheximide (50 micrograms/ml) failed to inhibit the induction of these mRNAs by either IFN-alpha or IFN-gamma, suggesting that their induction does not require de novo protein synthesis. DNA sequence analysis of this cDNA reveals that it encodes a protein of Mr 53,168 that has sequence homology with and the biological activity of a tryptophanyl-tRNA synthetase, an enzymatic activity that has been demonstrated to play a role in and be modulated by the growth of cells. Elevated levels of this enzyme may be involved in the cell growth inhibitory activity of the IFNs.

[Preliminary study of therapeutical mechanism on chyluria by heat-cleaning and hemostasis drugs]

Ten cases of filarial chyluria were treated with Chinese medical herbs. The results showed that the average concentration of serum histamine of 142 ng/ml before treatment dropped to 93 ng/ml after treatment. The average lymph-vessel pressure of 9.93 cmH2O in dorsalis pedis dropped to 4.74 cmH2O after cure. The prevalent microcirculation obstacle of medium to serious grade also was improved or recovered. The average serum viscosity of 1,884 before treatment dropped to 1,725. These results indicated that the chronic lymphatic inflammation occurring in pelvis or behind peritoneum due to perennial stimulation of adult filariae, caused the high concentration of inflammatory medium tissues, the expansion of micro-vessels and the increase of lymph-vessel pressure. Therefore, the microcirculation obstacle was the principle pathogeny of filarial chyluria.