TY - JOUR
T1 - Hypoxic-induced truncation of voltage-dependent anion channel 1 is mediated by both asparagine endopeptidase and calpain 1 activities
AU - Pahima, Hadas
AU - Reina, Simona
AU - Tadmor, Noa
AU - Dadon-Klein, Daniella
AU - Shteinfer-Kuzmine, Anna
AU - Mazure, Nathalie M.
AU - de Pinto, Vito
AU - Shoshan-Barmatz, Varda
N1 - Publisher Copyright:
© Pahima et al.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - The voltage-dependent anion channel 1 (VDAC1), an outer mitochondria membrane (OMM) protein, serves as a mitochondrial gatekeeper, mediating the transport of nucleotides, Ca2+ and other metabolites across the OMM. VDAC1 also plays a central role in mitochondria-mediated apoptosis by facilitating the release of apoptotic proteins and by association with both pro- and anti-apoptotic proteins. Tumor cells, which are constantly exposed to hypoxic conditions, affect the cell via the transcription factor hypoxia-inducible factor (HIF) that induces transcriptional activity. In cultured cells and in lung cancer patients, hypoxia induces VDAC1 truncation at the C-terminus (VDAC1- ΔC). However, the molecular mechanisms involved in VDAC1-ΔC formation are unknown. Here, we show that hypoxia-induced VDAC1-ΔC formation is inhibited by the Ca2+ chelator BAPTA-AM, by calpain inhibitor-1, by inhibitor of the asparagine endopeptidase (AEP) and by si-RNA targeting HIF1-α or Ca2+-activated protease calpain-1 expression but not that of calpain-2. Finally, VDAC1-ΔC expressed in bacteria and reconstituted into a planar lipid bilayer exhibited decreased channel conductance relative to the full-length protein, yet retained voltage-dependent conductance. These findings suggest that hypoxia, acting via HIF-1a expression, leads to VDAC1 cleavage involving the activation of calpain 1 and AEP.
AB - The voltage-dependent anion channel 1 (VDAC1), an outer mitochondria membrane (OMM) protein, serves as a mitochondrial gatekeeper, mediating the transport of nucleotides, Ca2+ and other metabolites across the OMM. VDAC1 also plays a central role in mitochondria-mediated apoptosis by facilitating the release of apoptotic proteins and by association with both pro- and anti-apoptotic proteins. Tumor cells, which are constantly exposed to hypoxic conditions, affect the cell via the transcription factor hypoxia-inducible factor (HIF) that induces transcriptional activity. In cultured cells and in lung cancer patients, hypoxia induces VDAC1 truncation at the C-terminus (VDAC1- ΔC). However, the molecular mechanisms involved in VDAC1-ΔC formation are unknown. Here, we show that hypoxia-induced VDAC1-ΔC formation is inhibited by the Ca2+ chelator BAPTA-AM, by calpain inhibitor-1, by inhibitor of the asparagine endopeptidase (AEP) and by si-RNA targeting HIF1-α or Ca2+-activated protease calpain-1 expression but not that of calpain-2. Finally, VDAC1-ΔC expressed in bacteria and reconstituted into a planar lipid bilayer exhibited decreased channel conductance relative to the full-length protein, yet retained voltage-dependent conductance. These findings suggest that hypoxia, acting via HIF-1a expression, leads to VDAC1 cleavage involving the activation of calpain 1 and AEP.
KW - Asparagine endopeptidase
KW - Calpain
KW - Hypoxia
KW - VDAC1
UR - http://www.scopus.com/inward/record.url?scp=85042560448&partnerID=8YFLogxK
U2 - 10.18632/oncotarget.24377
DO - 10.18632/oncotarget.24377
M3 - Article
AN - SCOPUS:85042560448
SN - 1949-2553
VL - 9
SP - 12825
EP - 12841
JO - Oncotarget
JF - Oncotarget
IS - 16
ER -