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A new molecular mechanism of evasion of apoptosis revealed by novel C‐kinase activity reporter
Author(s) -
Kajimoto Taketoshi,
Caliman Alisha D.,
Tobias Irene S.,
Okada Taro,
Pilo Caila A.,
Van An-Angela N.,
McCammon J. Andrew,
Nakamura Shun-ichi,
Newton Alexandra C.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.03250
Subject(s) - microbiology and biotechnology , apoptosis , biology , protein kinase c , programmed cell death , cancer cell , signal transduction , kinase , biochemistry , cancer , genetics
It is well known that cells, especially cancer cells, have an ability of evasion of apoptosis by cellular stress like nutrient starvation. And the balance between apoptosis signal and apoptosis‐resistant signal will determine the fate of cells, dead or alive. Here we found new cell signaling system that plays a role in applying the brakes to cell death that in case cancer cells avoid apoptosis by cellular stress like starvation using newly developed biosensor and in silico docking simulation technique. The new cell signaling system is that second messenger, sphingosine 1‐phosphate (S1P), directly activates a key cell signaling protein, atypical protein kinase C (aPKC). First, we found that the inhibition of aPKC induces apoptosis of cancer cell lines. Next, for making clear the molecular mechanism of the aPKC‐induced apoptosis resistance, we generated a genetically encoded reporter with the same modular structure as the original C kinase activity reporter (CKAR) but with a unique substrate sequence that allows specific visualization of atypical PKC activity in cells. Using the atypical PKC‐specific CKAR (aCKAR) we found that intracellular S1P induces the activation of atypical PKC in an S1P receptor‐independent manner. Biochemical studies revealed that S1P directly binds to the kinase domain of atypical PKC isozymes, relieving autoinhibitory constraints to activate the enzyme. In silico docking studies were used to identify potential binding sites for aPKC, one of which was validated by biochemical and aCKAR imaging techniques. Now we got new insights about the player of evasion of apoptosis in cancer at the molecular level, and it has potential for development of new molecular‐targeted agents to release brakes against cell death. Support or Funding Information This study was supported by NIH to A.C.N., JSPS KAKENHI, Kobe University Grant for Japan‐US Collaboration, Nakatani Foundation Grant for Technology Development Research to T.K., NIH, HHMI, NBCR, NSF to J.A.M., JSPS KAKENHI to S.N. and T.O. A.D.C. was supported in part by the UCSD Graduate Training Program in Cellular and Molecular Pharmacology.