LIM kinases (LIMKs) regulate actin polymerization by phosphorylating cofilin and are predominantly expressed in neural tissue. In this study, the effect of LIMK1 overexpression in PC12 cell apoptosis was investigated. PC12 cells overexpressing the wild-type LIMK1 were more resistant to serum-withdrawal-induced cell death and the level of caspase 3 activation in these cells was lower than in the control PC12 cells or than in the PC12 cells expressing a mutant LIMK1 lacking the kinase domain. The inhibition of JNK activation was observed in the PC12 cells overexpressing the wild-type LIMK1 after serum withdrawal. These results suggest that the LIMK1 might allow resistance to apoptosis in PC12 cells by inhibiting JNK activation.
|Number of pages||12|
|Journal||Cellular and molecular neurobiology|
|Publication status||Published - 2004 Apr|
Bibliographical noteFunding Information:
In this study, it was found that LIMK over-expression increased the level of resistance to apoptosis in PC12 cells when they were starved. The PC12 cells expressing the wild-type LIMK1 were more resistant to serum-withdrawal-induced apoptosis. When the cells were starved for 24 h, 2/3 of the control PC12 cells had undergone cell death. However, less than 1/3 of PC12 cells over-expressing the wild-type LIMK were positive for PI staining. This result of a change in apoptosis was supported by caspase 3 activation. We examined the involvement of casapse 3 activation using two approaches. First, caspase 3 activation was evaluated by a flurometric assay using a fluogenic substrate, DEVD-AFC. Caspase 3 activity was inhibited in the L13 cells (wild-type LIMK1 transfectants) compared to the PC12 cells without LIMK over-expression or S36 cells expressing the mutant LIMK1. Second, Western blotting was done to detect active caspase 3. In control PC12 cells, active casapse 3 was detected at 12 and 16 h after serum withdrawal, whereas caspase 3 activation was not detected in L13 cells. Our results suggest that the caspase-3-like proteases or, more likely, caspase 3 are activated during the apoptotic death of starvation-induced cell death and is inhibited by LIMK1 over-expression.
All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience
- Cell Biology