Murine gammaherpesvirus (MHV) MK3 gene sequence diversity among 72, 4556, and 68 strains.

Murid herpesvirus 4 (MuHV-4) currently serves as a model for study of human gamma-herpesvirus pathogenesis. It codes for MK3 protein that similarly as K5 protein of Kaposi's sarcoma-associated herpesvirus are members of a family of structurally related viral immune evasion molecules possessing RING-CH finger domain with ubiquitin ligase activity. Murine herpesvirus 72 (MHV-72) isolated from the same species of free-living small rodent is considered as closely related to Murine herpesvirus 68 (MHV-68). Studies on MHV-72, identified dissimilarity from MHV-68 in the sequence of glycoprotein 150 [K. Macáková, J. Matis, I. Rezuchová, O. Kúdela, H. Raslová, M. Kúdelová, Virus Genes 26, 89-95 (2003)]. Murine herpesvirus 4556 (MHV-4556) is relatively new, till now, uncharacterised strain isolated from different murid species Apodemus flavicollis. We have therefore sequenced the MK3 gene of MHW-72 as well as of MHV-4556 to find out the evidence of their difference from that of MHV-68. We show here the unique nucleotide mutation in MHV-72 MK3 gene changing the codon at C-end of MK3 protein that was earlier predicted to function in interaction with TAP1/2. Furthermore, one from two nucleotide mutations found for MHV-4556 MK3 gene changed the codon that is localized at N-terminus of MK3 protein. MHV-4556-specific mutation was found within MK3 RING-CH finger domain known to be necessary for the ubiquitination of MHC class I proteins. Moreover, the latter established the new restriction site specific for MHV-4556.

Murine gammaherpesvirus (MHV) M7 gene encoding glycoprotein 150 (gp150): difference in the sequence between 72 and 68 strains.

Murine gamma herpesvirus 72 (MHV-72) was isolated from the same species of free-living small rodent as MHV-68 which currently serves as a model for study of human gamma-herpesvirus pathogenesis. MHV-68 open reading frame (ORF) M7 encodes a virus-associated transmembrane glycoprotein 150 (gp150) and displays sequence homology with Epstein-Barr virus (EBV) membrane antigen gp350/220. MHV-68 was used to model potential efficacy of EBV gp350 as an immunogen to protect against virus-associated disease. Studies on MHV-72, which is considered as closely related to MHV-68, identified some dissimilarity from MHV-68. By the contrast to MHV-68, abnormal lymphocytes have been described after infection with MHV-72. We have therefore sequenced the MHV-72 gp150 gene to find out the evidence of difference from that of MHV-68. We show here that from five nucleotide mutations found four changed the codon. Three codon changes are mapped out of two gp150 transmembrane domains and out of proline rich repeat region, respectively. Possible changes in the predicted secondary structure are discussed.

Biglycan, a nitric oxide-regulated gene, affects adhesion, growth, and survival of mesangial cells.

During glomerular inflammation mesangial cells are the major source and target of nitric oxide that pro-foundly influences proliferation, adhesion, and death of mesangial cells. The effect of nitric oxide on the mRNA expression pattern of cultured rat mesangial cells was therefore investigated by RNA-arbitrarily-primed polymerase chain reaction. Employing this approach, biglycan expression turned out to be down-regulated time- and dose-dependently either by interleukin-1beta-stimulated endogenous nitric oxide production or by direct application of the exogenous nitric oxide donor, diethylenetriamine nitric oxide. There was a corresponding decline in the rate of biglycan biosynthesis and in the steady state level of this proteoglycan. In vivo, in a model of mesangioproliferative glomerulonephritis up-regulation of inducible nitric-oxide synthase mRNA was associated with reduced expression of biglycan in isolated glomeruli. Biglycan expression could be normalized, both in vitro and in vivo, by using a specific inhibitor of the inducible nitric-oxide synthase, l-N6-(l-iminoethyl)-l-lysine dihydrochloride. Further studies showed that biglycan inhibited cell adhesion on type I collagen and fibronectin because of its binding to these substrates. More importantly, biglycan protected mesangial cells from apoptosis by decreasing caspase-3 activity, and it counteracted the proliferative effects of platelet-derived growth factor-BB. These findings indicate a signaling role of biglycan and describe a novel pathomechanism by which nitric oxide modulates the course of renal glomerular disease through regulation of biglycan expression.

Absence of decorin adversely influences tubulointerstitial fibrosis of the obstructed kidney by enhanced apoptosis and increased inflammatory reaction.

Decorin, a small dermatan-sulfate proteoglycan, participates in extracellular matrix assembly and influences directly and indirectly cell behavior via interactions with signaling membrane receptors and transforming growth factor (TGF)-beta. We have therefore compared the development of tubulointerstitial kidney fibrosis in wild-type (WT) and decorin-/- mice in the model of unilateral ureteral obstruction. Without obstruction, kidneys from decorin-/- mice did not differ in any aspect from their WT counterparts. However, already 12 hours after obstruction decorin-/- animals showed lower levels of p27(KIP1) and soon thereafter a more pronounced up-regulation and activation of initiator and effector caspases followed by enhanced apoptosis of tubular epithelial cells. Later, a higher increase of TGF-beta1 became apparent. After 7 days, there was an up to 15-fold transient up-regulation of the related proteoglycan biglycan, which was mainly caused by the appearance of biglycan-expressing mononuclear cells. Other small proteoglycans showed no similar response. Because of enhanced degradation of type I collagen, end-stage kidneys from decorin-/- animals were more atrophic than WT kidneys. These data suggest that decorin exerts beneficial effects on tubulointerstitial fibrosis, primarily by influencing the expression of a key cyclin-dependent kinase inhibitor and by limiting the degree of apoptosis, mononuclear cell infiltration, tubular atrophy, and expression of TGF-beta1.