Korean J Physiol Pharmacol.  2018 Jul;22(4):457-465. 10.4196/kjpp.2018.22.4.457.

Effect of BIS depletion on HSF1-dependent transcriptional activation in A549 non-small cell lung cancer cells

Affiliations
  • 1Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea. leejh@catholic.ac.kr
  • 2The Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
  • 3Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, Chosun University School of medicine, Gwangju 61452, Korea.
  • 4Genome Editing Research Center, KRIBB, Daejeon 34141, Korea.
  • 5Department of Biomolecular Science, Korea University of Science and Technology, Daejeon 34113, Korea.

Abstract

The expression of BCL-2 interacting cell death suppressor (BIS), an anti-stress or anti-apoptotic protein, has been shown to be regulated at the transcriptional level by heat shock factor 1 (HSF1) upon various stresses. Recently, HSF1 was also shown to bind to BIS, but the significance of these protein-protein interactions on HSF1 activity has not been fully defined. In the present study, we observed that complete depletion of BIS using a CRISPR/Cas9 system in A549 non-small cell lung cancer did not affect the induction of heat shock protein (HSP) 70 and HSP27 mRNAs under various stress conditions such as heat shock, proteotoxic stress, and oxidative stress. The lack of a functional association of BIS with HSF1 activity was also demonstrated by transient downregulation of BIS by siRNA in A549 and U87 glioblastoma cells. Endogenous BIS mRNA levels were significantly suppressed in BIS knockout (KO) A549 cells compared to BIS wild type (WT) A549 cells at the constitutive and inducible levels. The promoter activities of BIS and HSP70 as well as the degradation rate of BIS mRNA were not influenced by depletion of BIS. In addition, the expression levels of the mutant BIS construct, in which 14 bp were deleted as in BIS-KO A549 cells, were not different from those of the WT BIS construct, indicating that mRNA stability was not the mechanism for autoregulation of BIS. Our results suggested that BIS was not required for HSF1 activity, but was required for its own expression, which involved an HSF1-independent pathway.

Keyword

A549; BCL-2 interacting cell death suppressor; Heat shock factor1; Heat shock protein
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