Gene expression profile and overexpression of apoptosis-related genes (NGFI-B and Gadd 45 γ) in early phase of Thy-1 nephritis model

Abstract

Mesangioproliferative glomerulonephritis (MPGN) is a disease of high incidence in humans. Rat Thy-1 nephritis (Thy-1 N), namely, anti-thymocyte serum (ATS)-induced nephritis, is considered to be an animal model for studying MPGN. Although previous studies have demonstrated that glomerular mesangial cell (GMCs) injury might be a feature of Thy-1 N, the mechanism of the disease (i.e., GMC apoptosis) remains unclear. We have examined the pathologic changes of GMCs and the gene expression profile of renal tissues in Thy-1 N. The pathologic changes of Thy-1 N include three phages: GMC apoptosis (40 min), necrosis (2 h), and proliferation (5 days). Many TUNEL-positive cells are found 40 min after administration of ATS. Concomitantly, 341 genes are up-regulated, whereas 392 genes are down-regulated, as shown by microarrays analysis. The mRNA and protein of two of the up-regulated genes (nerve growth factor induced protein I-B, NGFI-B; growth arrest- and DNA-damage-inducible protein 45 gamma, Gadd 45 gamma) in the GMC apoptotic phase of Thy-1 N are markedly elevated, as observed by real-time polymerase chain reaction and immunohistochemistry. Our data indicate that pathologic changes of Thy-1 N are involved in the abnormal gene profile. The overexpression of the NGFI-B and Gadd 45 gamma genes may be associated with GMC apoptosis of Thy-1 N.

Apoptosis of glomerular mesangial cells induced by sublytic C5b‐9 complexes in rats with Thy‐1 nephritis is dependent on Gadd45γ upregulation

“…Several studies show that Gadd45 proteins not only induce cell G2/M arrest and inhibit cell entry into S phase, but also promote cell apoptosis [16][17][18][19]. Our previous microarray analysis detected the up-regulated expression of Gadd45g gene in the renal tissue of Thy-1N rats [20] and in GMC stimulated by sublytic C5b-9 complexes (unpublished data). However, the role of Gadd45g gene in GMC apoptosis of Thy-1N remains to be defined.…”

“…Our previous studies using gene microarray analysis revealed that the expression of Gadd45g gene was upregulated in the renal tissue of Thy-1N rats and in GMC stimulated by sublytic C5b-9 (unpublished data). Both mRNA and protein expression of Gadd45g detected by real-time PCR and IHC staining in the early phase of the GMC apoptosis in Thy-1N are remarkably increased [20], suggesting that up-regulation of Gadd45g expression may play a role in the GMC apoptosis. It is possible that the upregulation of Gadd45g expression is a mediator of GMC apoptosis.…”

“…In the early phase of Thy-1N, GMC are targeted by antiThy-1 Ab resulting in immediate complement activation and cell injury [6]. There is growing interest in studying GMC apoptosis and its involvement in the initiation and development of the nephritis [11,20,21]. Shimizu et al [4] reported that GMC apoptosis in the rats with Thy-1N occurs rapidly (within 1 or 2 h).…”

“…Early studies of Thy-1N have demonstrated that the damage of GMC is complement-dependent and neutrophil-independent [6,9]. Complement C5b-9, in particular sublytic C5b-9, can induce sublethal injury and activate various metabolic processes including expression of many pathogenic genes [9,20,22,23]. Subsequent experiments have confirmed that systemic complement depletion can reduce mesangiolysis, GMC proliferation and glomerular platelet and macrophage influx [21].…”

“…To quantify glomerular apoptotic cells, the number of TUNEL-positive nuclei in 100 glomerular cross sections was counted in a doubleblinded manner by two independent observers for each rat. Numbers of glomerular apoptotic cells were expressed as the mean number per glomerular cross section as described previously [20,29,57]. …”