Fibroblasts derived from the progeroid
Werner syndrome show reduced replicative lifespan and a "stressed" morphology, both alleviated using the MAP
kinase inhibitor
SB203580. However, interpretation of these data is problematical because although
SB203580 has the stress-activated
kinases p38 and JNK1/2 as its preferred targets, it does show relatively low overall
kinase selectivity. Several lines of data support a role for both p38 and JNK1/2 activation in the control of cellular proliferation and also the pathology of diseases of ageing, including type II diabetes, diseases to which
Werner Syndrome individuals are prone, thus making the use of JNK inhibitors attractive as possible
therapeutics. We have thus tested the effects of the widely used JNK inhibitor
SP600125 on the proliferation and morphology of WS cells. In addition we synthesised and tested two recently described
aminopyridine based inhibitors.
SP600125 treatment resulted in the cessation of proliferation of WS cells and resulted in a senescent-like cellular phenotype that does not appear to be related to the inhibition of JNK1/2. In contrast, use of the more selective
aminopyridine CMPD 6o at concentrations that fully inhibit JNK1/2 had a positive effect on cellular proliferation of immortalised WS cells, but no effect on the replicative lifespan of primary WS fibroblasts. In addition, CMPD 6o corrected the stressed WS cellular morphology. The
aminopyridine CMPD 6r, however, had little effect on WS cells. CMDP 6o was also found to be a weak inhibitor of MK2, which may partially explain its effects on WS cells, since MK2 is known to be involved in regulating cellular morphology via HSP27 phosphorylation, and is thought to play a role in cell cycle arrest. These data suggest that total JNK1/2 activity does not play a substantial role in the proliferation control in WS cells.