Biochemical and biophysical research communications
-
Biochem. Biophys. Res. Commun. · Apr 2004
Transcription factor Sp1 mediates p38MAPK-dependent activation of the p21WAF1 gene promoter in vascular smooth muscle cells by pyrrolidine dithiocarbamate.
Previously, we demonstrated that pyrrolidine dithiocarbamate (PDTC) induced G1 cell cycle arrest in vascular smooth muscle cells (VSMC) through inducing p21WAF1 expression. It has recently been reported that the transcription factors involved in p21WAF1 activation by certain signaling factors may vary in different cell types. However, little is known concerning the molecular mechanisms by which PDTC induces p21WAF1 gene expression in VSMC. ⋯ Treatment with SB203580, an inhibitor of the p38MAPK, significantly down-regulated transactivation of PDTC-induced Sp1. Finally, the transient expression of VSMC with dominant negative p38MAPK plasmid suppressed PDTC-stimulated Sp1 activity. In conclusion, we report the novel finding that transcription factor Sp1 that is involved in the p38MAPK-mediated control of p21WAF1 regulation on VSMC in response to PDTC has now been identified.
-
Biochem. Biophys. Res. Commun. · Apr 2004
Antioxidative treatment reverses imbalances of nitric oxide synthase isoform expression and attenuates tissue-cGMP activation in diabetic rats.
Oxidative stress and impaired bioactivity of vascular nitric oxide (NO) play an important role in the pathogenesis of macro- as well as microangiopathic complications in diabetes mellitus. To determine the cause of this impaired bioactivity, we tested the effect of long-term hyperglycemia and antioxidative treatment on tissue-specific endothelial (e)NOS- and inducible (i)NOS-expression and the main target of NO action, cGMP, in diabetic rats. After 4 weeks of hyperglycemia, eNOS-mRNA expression was significantly down-regulated in all tissues tested. ⋯ In addition, our data suggest that the cause of impaired endothelial vasodilatation in experimental diabetes is not degradation or inactivation of NO. On the contrary, these results support the concept of decreased reactivity of the vascular smooth muscle to NO or increased NO activity as a possible vascular damaging agent, e.g., by inducing apoptosis in vascular cells. Furthermore, our data show that antioxidative treatment is capable of reversing changes in the NO-cGMP system and may therefore be an important therapeutic option for preventing vascular damage in diabetes mellitus.
-
Biochem. Biophys. Res. Commun. · Mar 2004
P311 binds to the latency associated protein and downregulates the expression of TGF-beta1 and TGF-beta2.
P311 is an 8-kDa protein originally found in neurons and muscle. We recently showed that expression of P311 in NIH 3T3 cells induced a myofibroblast phenotype with low TGF-beta1 expression. Here we demonstrate that P311 downregulates not only TGF-beta1, but also TGF-beta2, expression, with no effect on TGF-beta3. ⋯ Deletion of the PEST domain reversed the effect of P311 on TGF-beta isoforms. Finally, Smad3 activity was decreased in P311-expressing cells, but was corrected by exogenous TGF-beta1 treatment, which also elevated TGF-beta1 mRNA level. This suggested that P311 downregulates TGF-beta1 and 2 in part by blocking TGF-beta autoinduction.
-
Biochem. Biophys. Res. Commun. · Mar 2004
Effect on ribonucleotide reductase of novel lipophilic iron chelators: the desferri-exochelins.
Desferri-exochelins are siderophores secreted by Mycobacterium tuberculosis that are both lipid- and water-soluble and have a high binding affinity for iron. Desferri-exochelin 772SM inhibits DNA replication and ribonucleotide reductase activity at 10-fold less concentration than the lipid-insoluble iron chelator deferoxamine, which is currently in clinical use. Neither chelator can extract iron directly from ribonucleotide reductase. However, because of its lipid-solubility and high binding affinity, desferri-exochelin is able to enter cells rapidly and access intracellular iron, while deferoxamine has limited capacity to cross the cell membrane.
-
Biochem. Biophys. Res. Commun. · Oct 2003
Identification of urotensin II-related peptide as the urotensin II-immunoreactive molecule in the rat brain.
Urotensin II (UII) has been reported as the most potent known vasoconstrictor. While rat and mouse orthologs of UII precursor protein have been reported, only the tentative structures of UII peptides of these animals have been demonstrated, since prepro-UII proteins lack typical processing sites for their mature peptides. In the present study, we isolated a novel peptide, UII-related peptide (URP), from the extract of the rat brain as the sole immunoreactive substance to anti-UII antibody; the amino acid sequence of the peptide was determined as ACFWKYCV. cDNAs encoding rat, mouse, and human precursor proteins for URP were cloned and revealed that the sequences of mouse and human URP peptides are the same as that for rat URP. ⋯ URP was found to bind and activate the human or rat UII receptors (GPR14) and showed a hypotensive effect when administered to anesthetized rats. These results suggest that URP is the endogenous and functional ligand for UII receptor in the rat and mouse, and possibly in the human. We also describe the preparation of specific monoclonal antibodies raised against UII peptide and the establishment of a highly sensitive enzyme immunoassay system for UII peptides.