Journal of Bioenergetics and Biomembranes

, Volume 48, Issue 3, pp 211–225

The non-apoptotic action of Bcl-xL: regulating Ca2+ signaling and bioenergetics at the ER-mitochondrion interface

  • Abasha Williams
  • Teruo Hayashi
  • Daniel Wolozny
  • Bojiao Yin
  • Tzu-Chieh Su
  • Michael J. Betenbaugh
  • Tsung-Ping Su
Article

DOI: 10.1007/s10863-016-9664-x

Cite this article as:
Williams, A., Hayashi, T., Wolozny, D. et al. J Bioenerg Biomembr (2016) 48: 211. doi:10.1007/s10863-016-9664-x

Abstract

Bcl-2 family proteins are known to competitively regulate Ca2+; however, the specific inter-organelle signaling pathways and related cellular functions are not fully elucidated. In this study, a portion of Bcl-xL was detected at the ER-mitochondrion interface or MAM (mitochondria-associated ER membrane) in association with type 3 inositol 1,4,5-trisphosphate receptors (IP3R3); an association facilitated by the BH4 and transmembrane domains of Bcl-xL. Moreover, increasing Bcl-xL expression enhanced transient mitochondrial Ca2+ levels upon ER Ca2+ depletion induced by short-term, non-apoptotic incubation with thapsigargin (Tg), while concomitantly reducing cytosolic Ca2+ release. These mitochondrial changes appear to be IP3R3-dependent and resulted in decreased NAD/NADH ratios and higher electron transport chain oxidase activity. Interestingly, extended Tg exposure stimulated ER stress, but not apoptosis, and further enhanced TCA cycling. Indeed, confocal analysis indicated that Bcl-xL translocated to the MAM and increased its interaction with IP3R3 following extended Tg treatment. Thus, the MAM is a critical cell-signaling junction whereby Bcl-xL dynamically interacts with IP3R3 to coordinate mitochondrial Ca2+ transfer and alters cellular metabolism in order to increase the cells’ bioenergetic capacity, particularly during periods of stress.

Keywords

Bcl-xL Bioenergetics Calicum signaling Mitochondria ER MAM IP3R3 

Abbreviations

AUC

Area under the curve

BAPTA

1,2-bis(o-aminophenoxy)ethane-N,N,N’,N’-tetraacetic acid

Bcl-2

B-cell lymphoma-2

Bcl-xL

B-cell lymphoma-extra large

BiP

Binding immunoglobulin protein

Cyto

Cytosol

DsRed

Discosoma sp.red fluorescent protein

ERp75

Endoplasmic reticulum resident protein 75

FRET

Fluorescence energy resonance transfer

Grp75

Glucose regulated protein 75

HcRed

Heteractis crispa far-red fluorescent protein

HEPES

4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid

His

Histidine

IP3R

Inositol 1,4,5-trisphophate receptor

IRE1

Inositol-requiring enzyme 1

KHB

Krebs-HEPES Buffer

MAM

Mitochondria-associated ER membrane

Mfn2

Mitofusin 2

Mito

Mitochondria

NAD

Nicotinamide adenine dinucleotide

NADH

Nicotinamide adenine dinucleotide reduced

NP62

Nucleoporin 62

OMM

Outer mitochondria membrane

PERK

RNA-dependent protein kinase-like ER kinase

P1

Whole cell/nuclear

P3

Microsome

RFU

Relative fluorescence units

RLU

Relative fluorescence units

Sig-1R

σ-1 receptor

TCA

Tricarboxylic acid

Tg

Thapsigargin

TM

Transmembrane

Tomm20

Translocase of the outer mitochondrial membrane

Tun

Tunicamycin

VDAC

Voltage-gated anion channel

YFP

Yellow fluorescent protein.

Supplementary material

10863_2016_9664_MOESM1_ESM.pdf (211 kb)
Figure S1(PDF 211 kb)
10863_2016_9664_MOESM2_ESM.pdf (93 kb)
Figure S2(PDF 92 kb)
10863_2016_9664_MOESM3_ESM.pdf (178 kb)
Figure S3(PDF 177 kb)
10863_2016_9664_MOESM4_ESM.pdf (820 kb)
Figure S4(PDF 819 kb)
10863_2016_9664_MOESM5_ESM.pdf (73 kb)
Figure S5(PDF 72 kb)
10863_2016_9664_MOESM6_ESM.pdf (592 kb)
Figure S6(PDF 591 kb)
10863_2016_9664_MOESM7_ESM.pdf (770 kb)
Figure S7(PDF 770 kb)
10863_2016_9664_MOESM8_ESM.pdf (104 kb)
Figure S8(PDF 104 kb)

Copyright information

© Springer Science+Business Media New York (outside the USA) 2016

Authors and Affiliations

  • Abasha Williams
    • 1
    • 2
    • 3
  • Teruo Hayashi
    • 1
    • 4
  • Daniel Wolozny
    • 2
  • Bojiao Yin
    • 2
  • Tzu-Chieh Su
    • 1
  • Michael J. Betenbaugh
    • 2
  • Tsung-Ping Su
    • 1
  1. 1.Cellular Pathobiology Section, IRP, NIDA, NIH, DHHSBaltimoreUSA
  2. 2.Department of Chemical and Biomolecular EngineeringJohns Hopkins UniversityBaltimoreUSA
  3. 3.Division of Biotechnology Review and Research II, FDA/CDER/OPS/OBPSilver SpringUSA
  4. 4.Seiwakai Nishikawa HospitalHamadaJapan