Skip to main content
PMC home page
Cellular & Molecular Biology Letters logoLink to Cellular & Molecular Biology Letters
. 2007 Oct 29;13(1):119–129. doi: 10.2478/s11658-007-0042-x

Acidification induces Bax translocation to the mitochondria and promotes ultraviolet light-induced apoptosis

Lin Yang 1,✉, Yongyu Mei 1, Qifeng Xie 1, Xiaoyan Han 2, Fucheng Zhang 2, Lin Gu 1, Yufeng Zhang 1, Youming Chen 1, Gang Li 1, Zhiliang Gao 1
PMCID: PMC6275645  PMID: 17965970

Abstract

It has been suggested that Bax translocation to the mitochondria is related to apoptosis, and that cytosol acidification contributes to apoptosis events. However, the mechanisms remain obscure. We investigated the effect of acidification on Bax translocation and on ultraviolet (UV) light-induced apoptosis. The Bax translocation assay in vitro showed that Bax translocated to the mitochondria at pH 6.5, whereas no Bax translocation was observed at pH 7.4. VHDBB cells expressing the GFP-Bax fusion protein were treated for 12 h with a pH 6.5 DMEM medium, nigericin (5 μg/ml) and UV light (50 J/cm2), separately or in combination, and Bax translocation to the mitochondria was determined by SDS-PAGE and Western blot, and apoptotic cell death was detected by flow cytometry. The results showed that some of the Bax translocated to the mitochondria in the cells treated with the normal medium, nigericin and UV in combination, whereas all of the Bax translocated to the mitochondria in the cells treated with the pH 6.5 medium, nigericin and UV in combination. In VHDBB cells treated for 12 h with nigericin, UV alone, and UV and nigericin in combination, the respective rates of apoptotic cell death were 25.08%, 33.25% and 52.88%. In cells treated with pH 6.5 medium and nigericin, pH 6.5 medium and UV, and pH 6.5 medium, nigericin and UV in combination, the respective rates of apoptotic cell death increased to 37.19%, 41.42% and 89.44%. Our results indicated that acidification induces Bax translocation from the cytosol to the mitochondria, and promotes UV lightmediated apoptosis. This suggests that there is a possibility of improving cancer treatment by combining acidification with irradiation or chemotherapeutic drugs.

Key words: Acidification, Bax, Translocation, Ultraviolet light, Apoptosis, Cancer

Full Text

The Full Text of this article is available as a PDF (500.7 KB).

Abbreviations used

Cyto

cytosol

Mito

mitochondria

Nig

nigericin

UV

ultraviolet

References

  • 1.Adams J.M., Cory S. Life-or-death decisions by the Bcl-2 protein family. Trends Biochem. Sci. 2001;26:61–66. doi: 10.1016/S0968-0004(00)01740-0. [DOI] [PubMed] [Google Scholar]
  • 2.Cory S., Adams J.M. The Bcl2 family: Regulators of the cellular life-ordeath switch. Nat. Rev. 2002;2:647–656. doi: 10.1038/nri885. [DOI] [PubMed] [Google Scholar]
  • 3.Huang D., Strasser A. BH3-only proteins-essential initiators of apoptotic cell death. Cell. 2000;103:839–842. doi: 10.1016/S0092-8674(00)00187-2. [DOI] [PubMed] [Google Scholar]
  • 4.Wolter K.G., Hsu Y.T., Smith C.L., Nechushtan A., Xi X.G. Movement of bax from the cytosol to mitochondria during apoptosis. J. Cell Biol. 1997;139:1281–1292. doi: 10.1083/jcb.139.5.1281. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5.Hsu Y.T., Wolter K.G., Youle R.J. Cytosol to-membrane redistribution of bax and bcl-xl during apoptosis. Proc. Natl. Acad. Sci. USA. 1997;94:3668–3672. doi: 10.1073/pnas.94.8.3668. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 6.Dejean L.M., Martinez-Caballero S., Guo L., Hughes C., Teijido O., Ducret T., Ichas F., Korsmeyer S.J., Antonsson B., Jonas E.A., Kinnally K.W. Oligomeric Bax is a component of the putative cytochrome c release channel MAC, mitochondrial apoptosis-induced channel. Mol. Biol. Cell. 2005;16:2424–2432. doi: 10.1091/mbc.E04-12-1111. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7.Hsu Y.T., Youle R.J. Nonionic detergents induce dimerization among members of the bcl-2 family. J. Biol. Chem. 1997;272:13829–13834. doi: 10.1074/jbc.272.21.13829. [DOI] [PubMed] [Google Scholar]
  • 8.Smaili S.S., Hsu Y.T., Sanders K.M., Russell J.T., Youle R.J. Bax translication to mitochondria subsequent to rapid loss of mitochondrial membrane potential. Cell Death Differ. 2001;8:909–920. doi: 10.1038/sj.cdd.4400889. [DOI] [PubMed] [Google Scholar]
  • 9.Antonsson B., Montessuit S., Sanchez B., Martinou J.C. Bax is presents as a high molecular weight oligomer/complex in the mitochondrial membrane of apoptotic cells. J. Biol. Chem. 2001;276:1615–1623. doi: 10.1074/jbc.M010810200. [DOI] [PubMed] [Google Scholar]
  • 10.Dubrez L., Coll J.L., Hurbin A., Solary E., Favrot M.C. Caffeine sensitizes human H358 cell line to p53-mediated apoptosis by inducing mitochondrial translocation and conformational change of BAX protein. J. Biol. Chem. 2001;276:38980–38987. doi: 10.1074/jbc.M102683200. [DOI] [PubMed] [Google Scholar]
  • 11.Gottlieb R.A., Nordberg J., Skowronski E., Babior B.M. Apoptosis induced in Jurkat cells by several agents is preceded by intracellular acidification. Proc. Natl. Acad. Sci. USA. 1996;93:654–658. doi: 10.1073/pnas.93.2.654. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12.Sala P.P., Escobar D.C., Mollinedo F. Intracellular alkalinization suppresses lovastation-induced apoptosis in HL-60 cells through the inactivation of a pH-dependent endonuclease. J. Biol. Chem. 1995;270:6235–6242. doi: 10.1074/jbc.270.11.6235. [DOI] [PubMed] [Google Scholar]
  • 13.Barriere H., Poujeol C., Tauc M., Blasi J.M. CFTR modulates programmed cell death by decreasing intracellular pH in Chinese hamaster lung fibroblasts. Am. J. Physiol. Cell Physiol. 2001;281:C810–824. doi: 10.1152/ajpcell.2001.281.3.C810. [DOI] [PubMed] [Google Scholar]
  • 14.Barry M.A., Reynolds J.E., Eastman A. Etoposide-induced apoptosis in human HL-60 cells is associated with intracellular acidification. Cancer Res. 1993;53(10):2349–2357. [PubMed] [Google Scholar]
  • 15.Goossens J.F., Henichart J.P., Dassonneville L., Facompre M., Bailly C. Relation between intracellular acidification and camptothecin-induced apoptosis in leukemia cells. Eur. J. Pharm. Sci. 2000;10:125–131. doi: 10.1016/S0928-0987(99)00091-3. [DOI] [PubMed] [Google Scholar]
  • 16.Angoli D., Delia D., Wanke E. Early cytoplasmic acidification in retinamide-mediatewd apoptosis of human promyelocytic leukemia cells. Biochem. Biophys. Res. Commun. 1996;229:681–685. doi: 10.1006/bbrc.1996.1863. [DOI] [PubMed] [Google Scholar]
  • 17.Famulski K.S., Macdonald D., Paterson M.C., Sikora E. Activation of a low pH-dependent unclease by apoptotic agents. Cell Death Differ. 1999;6:281–289. doi: 10.1038/sj.cdd.4400495. [DOI] [PubMed] [Google Scholar]
  • 18.Segal M.S., Beem E. Effect of pH, ionic charge, and osmolality on cytochrome c-mediated caspase-3 activity. Am. J. Physiol. Cell Physiol. 2001;281:C1196–1204. doi: 10.1152/ajpcell.2001.281.4.C1196. [DOI] [PubMed] [Google Scholar]
  • 19.Furlong I.J., Ascaso R., Rivas A.L., Collins M.K. Intracellular acidification induces apoptosis by stimulating ICE-like protease. J. Cell Sci. 1997;110:653–661. doi: 10.1242/jcs.110.5.653. [DOI] [PubMed] [Google Scholar]
  • 20.Williams A.C., Collard T.J., Paraskeva C. An acidic environment leads to p53 dependent induction of apoptosis in human adenoma and carcinoma cell lines: implications for clonal selection during colorectal carcinogenesis. Oncogene. 1999;18:3199–3204. doi: 10.1038/sj.onc.1202660. [DOI] [PubMed] [Google Scholar]
  • 21.Collins M.K., Furlong I.J., Malde P., Ascaso R., Oliver J. An apoptotic endonuclease activated either by decreasing pH or by increasing calcium. J. Cell Sci. 1996;109:2393–2399. doi: 10.1242/jcs.109.9.2393. [DOI] [PubMed] [Google Scholar]
  • 22.Juin P., Hueber A.O., Littlewood T., Evan G. c-Myc-induced sensitization to apoptosis is mediated through cytochrome c release. Genes Dev. 1999;13:1367–1381. doi: 10.1101/gad.13.11.1367. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23.Jia L., Macey M.G., Yin Y., Newland A.C., Kelsev S.M. Subcellular distribution and redistribution of Bcl-2 family proteins in human leukemia cells and undergoing apoptosis. Blood. 1999;93:2353–2359. [PubMed] [Google Scholar]
  • 24.Haq R., Zanke B. Inhibition of apoptotic signaling pathways in cancer cells as a mechanism of chemotherapy resistance. Cancer Metastasis Rev. 1998;17:233–239. doi: 10.1023/A:1006075007857. [DOI] [PubMed] [Google Scholar]
  • 25.Yamagata M., Tannock I.F. The chronic administration of drugs that inhibit the regulation of intracellular pH: invitro and anti-tumour effects. Br. J. Cancer. 1996;73:1328–1334. doi: 10.1038/bjc.1996.254. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Newell K., Wood P., Stratford I., Tannock I. Effects of agents which inhibit the regulation of intracellular pH on murine solid tumour. Br. J. Cancer. 1992;66:311–317. doi: 10.1038/bjc.1992.262. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 27.Suzuki M., Youle R.J., Tjandra N. Structure of bax: co-regulation of dimmer formation and intracellular localization. Cell. 2000;103:645–654. doi: 10.1016/S0092-8674(00)00167-7. [DOI] [PubMed] [Google Scholar]
  • 28.Cartron P.F., Moreau C., Oliver L., Mayat E., Meflah K., Vallette F.M. Involvement of the N-terminus of bax in its intracellular l ocalization and function. FEBS Lett. 2002;512:95–100. doi: 10.1016/S0014-5793(02)02227-5. [DOI] [PubMed] [Google Scholar]
  • 29.Gross A., Jockel J., Wei M.C., Korsmeyer S.J. Enforced dimerization of bax results its translocation, mitochondrial dysfunction and apoptosis. EMBO J. 1998;17:3878–3885. doi: 10.1093/emboj/17.14.3878. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 30.Stubbs M., McSheehy P.M., Griffiths J.R., Bashford C.L. Causes and consequences of tumor acidity and implications for treatment. Mol. Med. Today. 2000;6:15–19. doi: 10.1016/S1357-4310(99)01615-9. [DOI] [PubMed] [Google Scholar]

Articles from Cellular & Molecular Biology Letters are provided here courtesy of BMC

RESOURCES