Ganglioside GM3 inhibits the high glucose- and TGF-β1-induced proliferation of rat glomerular mesangial cells

Abrupt proliferation of glomerular mesangial cells (GMCs) is a common feature in the early stage of diabetic glomerulopathy, and ganglioside GM3 (NeuAc alpha 3Gal beta 4Glc beta 1Cer) is thought to regulate the proliferation of many cell types. Recently, we have reported ganglioside GM3 as a modulator of glomerular hypertrophy in streptozotocin-induced diabetic rats [Kwak, D.H., Rho, Y.I., kwon, O.D., Alm, S.H., Song, J.H., Choo, YK., Kim, S.J., Choi, BX., Jung, K.Y, 2003. Decreases of ganglioside GM3 in streptozotocin-induced diabetic glomeruli of rats. Life Sciences 72, 1997-2006]. This study examined whether modulation of cellular ganglioside GM3 could regulate the high glucose- and transforming growth factor-beta 1 (TGF-beta 1)-induced proliferation of GMCs. To pharmacologically modulate the cellular ganglioside GM3, GMCs originated from rat kidneys were cultured with exogenous ganglioside GN13 or d-threo-PDMP, an inhibitor of ganglioside synthesis, in the RPMI 1640 media containing normal (5.6 mM, NG) or high (25 mM, HG) glucose. HG, TGF-beta 1 (10 ng/ ml) and d-threo-PDMP (20 mu M) significantly stimulated the mesangial cell proliferation, whereas these increments were remarkable attenuated by exogenous ganglioside mixture (0.1-0.2 mg/ml) or GM3 (20-100 mu M) in a dose-dependent manner. The mesangial cell proliferation caused by HG, TGF-beta 1 and d-threo-PDMP was closely correlated with decreases in both cellular sialic acid contents and ganglioside GM3 synthase activity. Based upon the mobility on high-performance thin-layer chromatography (HPTLC), GMCs showed a complex pattern of ganglioside expression that consisted, at least, of five different components of gangliosides, mainly ganglioside GM3. HG, TGF-beta 1 and d-threo-PDMP induced a significant reduction of ganglioside expression with apparent changes in the composition of ganglioside GM3, and semi-quantitative analysis by HPTLC showed that ganglioside GM3 expression reduced to about 35-54% of control. These results provide a pathophysiological link between mesangial cell proliferation and ganglioside GM3 expression, indicating that exogenously added ganglioside GM3 inhibits the high-ambient glucose- and TGF-beta 1-induced proliferation of cultured GMCs. (c) 2005 Elsevier Inc. All rights reserved.