Role of ornithine decarboxylase for proliferation of mesangial cells in culture

Abstract

To elucidate the role of polyamine metabolism in the regulation of mesangial cell growth, we examined the involvement of ornithine decarboxylase (ODC), the rate limiting enzyme for polyamine synthesis, in the mitogenesis of cultured rat mesangial cells (MCs). Resting MCs, stimulated with fetal calf serum (FCS 10%), showed an induction of ODC activity from undetectable values in resting cells to mean = 5035 nmol CO2/10(10) cells.hr (range 3157 to 7154, N = 5), which is 25-fold above the detection limit. We found a single peak of ODC activity eight to ten hours after stimulation, declining to 22 to 34% of peak levels after 24 hours. 3H-thymidine (TdR) uptake, an S-phase marker of MC replication, peaked at 24 hours, reaching 10.7-fold values of resting MCs. ODC mRNA levels were low in resting cells. After serum stimulation there was a two- to 10-fold increase in ODC mRNA with a maximum after six hours. ODC activity with similar kinetics but lower peak levels was also induced by incubating MCs with mitogens, such as platelet-derived growth factor (PDGF-AB 20 ng/ml), arginine vasopressin (AVP 10(-7) M), phorbol myristate acetate (PMA 10(-7) M), interleukin 1 alpha and beta (IL-1 alpha 10 U/ml, IL-1 beta 10 U/ml). In the presence of alpha-difluoromethylornithine (DFMO), an enzyme-activated irreversible inhibitor of ODC, the growth rate of MCs, assessed by cell counts and by 3H-TdR uptake, was markedly reduced by 62 to 100%. This antiproliferative effect of DFMO could be reversed by addition of putrescine, the reaction product of ODC.(ABSTRACT TRUNCATED AT 250 WORDS)

E-Cadherin Expression Is Regulated by miR-192/215 by a Mechanism That Is Independent of the Profibrotic Effects of Transforming Growth Factor-β

“…Primary mesangial cells were isolated and cultured as previously described (21,22). Human conditionally immortalized podocytes were propagated as previously described (23).…”

Comparative effects of TGF? on proliferation of 7- and 14-day-old chick embryo fibroblasts and lack of involvement of the ODC/PA system in the TGF? signaling pathway

“…*P Ͻ 0.01 and **P Ͻ 0.001 versus proper control with none treatment; ***P Ͻ 0.01 and ****P Ͻ 0.001 versus TGF␤. (Schulze-Lohoff et al, 1991) inhibits DNA synthesis and makes most cell lines thus far examined unable to grow. Contrary to what was expected, PA levels comparable with those of quiescent cells triggered the reentry in the cell cycle and DNA replication.…”

“…After electrophoresis, the RNA was transferred to Hybond-N nylon membrane (Amersham, Buckinghamshire, U.K.) and fixed by baking for 2 hr at 80°C. The fixed RNA was hybridized with 10 6 cpm 32 P-labeled ODC complementary DNA (cDNA) probe, as described by Schulze-Lohoff et al (1991). The chick ODC DNA probe containing a 1.7-kb DNA was kindly provided by Dr. A.J.…”

Heparin inhibits phorbol ester‐induced ornithine decarboxylase gene expression in endothelial cells

“…Here we show that both FCS and PMA were able to stimulate ODC gene expression in HEC. ODC plays a rate limiting role in polyamine biosynthesis and is intimately associated with cell proliferation and function [49, 50]. Moreover, an increase in ODC gene expression has been observed in different cell types in response to a number of proliferative agents, including bFGF, serum and phorbol esters [27, 49, 51, 52].…”

“…ODC plays a rate limiting role in polyamine biosynthesis and is intimately associated with cell proliferation and function [49, 50]. Moreover, an increase in ODC gene expression has been observed in different cell types in response to a number of proliferative agents, including bFGF, serum and phorbol esters [27, 49, 51, 52]. The present observation that only part of FCS‐induced overexpression of ODC mRNA could be prevented by PKC inhibition or down‐regulation suggests that, similar to the FCS‐mediated increase in HEC DNA synthesis, the stimulation of ODC gene expression induced by serum might have occurred through different signal‐transduction pathways, presumably involving both PKC‐dependent and PKC‐independent mechanisms.…”