Nishimura M, Tanaka T, Yasuda T, Kurakata S, Kitagawa M, Yamada K, Saito Y, Hirai A
Department of Internal Medicine, Sakura National Hospital, Chiba-city, Japan.
Kidney Int. 1999 Feb;55(2):520-8. doi: 10.1046/j.1523-1755.1999.00292.x.
The mevalonate pathway is important for the biosynthesis of isoprenoids such as geranylgeranylpyrophosphate (GGPP) and farnesylpyrophosphate, as well as cholesterol. It has been reported that treatment with 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor ameliorates glomerular injury in several experimental models of progressive glomerular disease. However, the effect of HMG-CoA reductase inhibitor on mesangial cell function has not been fully understood. This investigation was performed to elucidate the role of a mevalonate metabolite(s) in mesangial cell proliferation and extracellular matrix accumulation.
Cycling or quiescent human mesangial cells were incubated in RPMI 1640 containing 10% heat-inactivated fetal calf serum (FCS) in the absence or presence of pravastatin, an inhibitor of HMG-CoA reductase, and mevalonate metabolites. Type IV collagen secretion, mRNA expression, and [3H]thymidine incorporation were measured. Cell cycle phases were monitored by flow cytometry.
Pravastatin inhibited FCS-stimulated type IV collagen secretion (IC50 = 210 microM) and mRNA expression. Pravastatin also inhibited FCS-stimulated [3H]thymidine incorporation (IC50 = 430 microM). Analysis with flow cytometry revealed that pravastatin inhibited the G1 to S phase transition of FCS-stimulated mesangial cells. Mevalonate reversed these inhibitory effects of pravastatin completely. Among two major metabolites of mevalonate, GGPP and farnesylpyrophosphate, only GGPP reversed pravastatin-induced inhibition of type IV collagen secretion, DNA synthesis, and the G1 to S phase progression.
These results suggest that GGPP plays critical roles for the type IV collagen secretion and G1 to S phase transition in FCS-stimulated human mesangial cells.
甲羟戊酸途径对于类异戊二烯如香叶基香叶基焦磷酸（GGPP）和法尼基焦磷酸以及胆固醇的生物合成很重要。据报道，在几种进行性肾小球疾病的实验模型中，用3-羟基-3-甲基戊二酰辅酶A（HMG-CoA）还原酶抑制剂治疗可改善肾小球损伤。然而，HMG-CoA还原酶抑制剂对系膜细胞功能的影响尚未完全了解。进行本研究以阐明甲羟戊酸代谢产物在系膜细胞增殖和细胞外基质积聚中的作用。
将处于增殖期或静止期的人系膜细胞在含有10%热灭活胎牛血清（FCS）的RPMI 1640培养基中培养，分别在不存在或存在普伐他汀（一种HMG-CoA还原酶抑制剂）和甲羟戊酸代谢产物的情况下进行培养。检测IV型胶原分泌、mRNA表达以及[3H]胸腺嘧啶核苷掺入情况。通过流式细胞术监测细胞周期阶段。
普伐他汀抑制FCS刺激的IV型胶原分泌（IC50 = 210 microM）和mRNA表达。普伐他汀还抑制FCS刺激的[3H]胸腺嘧啶核苷掺入（IC50 = 430 microM）。流式细胞术分析显示，普伐他汀抑制FCS刺激的系膜细胞从G1期到S期的转变。甲羟戊酸完全逆转了普伐他汀的这些抑制作用。在甲羟戊酸的两种主要代谢产物GGPP和法尼基焦磷酸中，只有GGPP逆转了普伐他汀诱导的IV型胶原分泌抑制、DNA合成抑制以及从G1期到S期的进程抑制。
这些结果表明，GGPP在FCS刺激的人系膜细胞中对IV型胶原分泌和从G1期到S期的转变起着关键作用。
