TAK1 promotes cell survival by TNFAIP3 and IL-8 dependent and NF-κB independent pathway in HeLa cells exposed to heat stress.

PURPOSE

Transforming growth factor-β-activated kinase 1 (TAK1) plays a role in inhibiting apoptosis in response to multiple stresses. In the present study, we investigated the role of TAK1 in cell death induced by heat stress (HS).

MATERIALS AND METHODS

TAK1 knockdown HeLa cells and their parental cells were exposed to HS at 44 °C for 15, 30, 45 min followed by colony formation assay. Heat shock proteins (HSPs) induction, NF-κB phosphorylation, and caspase-3 cleavage were estimated by western blotting using specific antibodies. Global gene expression analysis was performed using the GeneChip® system. The anti-apoptotic roles of the identified genes were elucidated using small interfering RNAs targeting those genes.

RESULTS

Heat sensitivity estimated by colony formation assay and caspase-3 cleavage increased in TAK1 knockdown cells. This sensitisation was not due to alterations in HSP induction or NF-κB phosphorylation as the expression levels of these proteins did not differ significantly between the TAK1 knockdown and the parent cells after HS exposure. The GeneChip® analysis revealed differences in gene expression between both cell variants after HS exposure and defined the genetic network associated with cell death. TNF-α interacting protein 3 (TNFAIP3) and Interleukin 8 (IL-8) are two of the identified genes. RNA interference against these genes increased the cleavage of caspase-3 and cell death after HS exposure.

CONCLUSION

Our findings reveal the role of TAK1 in thermoresistance and show that the mediation is independent of NF-κB phosphorylation but is dependent on TNFAIP3 and IL-8 induction.