Fibroblasts derived from the progeroid
Werner syndrome (WS) show reduced replicative lifespan and a "stressed" morphology, both phenotypes being alleviated by using the
p38 MAP kinase inhibitor
SB203580. Because p38 is a major hub for the control of stress-signalling pathways we were interested in examining the possible role for downstream
kinases in order to refine our understanding of the role of p38 signalling in regulation of WS cell growth. To this end we treated WS and normal fibroblasts with MK2 inhibitors to determine whether MK2 inhibition would affect either the growth or morphology of WS cells. The first inhibitor, 7,8-dihydroxy-2,4-diamino-3-cyanobenzopyranopyridine (inhibitor 2), resulted in inhibition of WS cell growth and had no effect on morphology, effects that occurred below the level needed to inhibit MK2 and thus suggestive of inhibitor toxicity. The second inhibitor, 2-(2-quinolin-3-ylpyridin-4-yl)-1,5,6,7-tetrahydro-4H-pyrrolo-[3,2-c]pyridin-4-one (CMPD16), resulted in a significant extension of WS fibroblast replicative capacity compared to normal cells. In addition, CMPD16 reverted the WS cellular morphology to that seen in normal dermal fibroblasts. These data suggest that MK2 activity plays a substantial role in proliferation control in WS cells. CMPD16 was not as effective in cellular lifespan extension as
SB203580, however, suggesting that, although MK2 is a downstream
kinase involved in cell cycle arrest, other p38 targets may play a role. Alternatively, as CMPD16 is toxic to cell growth at levels just above those that extend lifespan, it is possible that the therapeutic window is too small. However, as CMPD16 does show significant effects in WS fibroblasts, this acts as proof-of-principle for the efforts to design and synthesise improved MK2 inhibitors. As MK2 is involved in inflammatory processes and
inflammation plays a major role in WS phenotypes, these data suggest MK2 as a potential therapeutic target for the treatment of
Werner syndrome.