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p32 protein levels are integral to mitochondrial and endoplasmic reticulum morphology, cell metabolism and survival
- Source :
- Biochemical Journal
- Publication Year :
- 2013
-
Abstract
- p32 [also known as HABP1 (hyaluronan-binding protein 1), gC1qR (receptor for globular head domains complement 1q) or C1qbp (complement 1q-binding protein)] has been shown previously to have both mitochondrial and non-mitochondrial localization and functions. In the present study, we show for the first time that endogenous p32 protein is a mitochondrial protein in HeLa cells under control and stress conditions. In defining the impact of altering p32 levels in these cells, we demonstrate that the overexpression of p32 increased mitochondrial fibrils. Conversely, siRNA-mediated p32 knockdown enhanced mitochondrial fragmentation accompanied by a loss of detectable levels of the mitochondrial fusion mediator proteins Mfn (mitofusin) 1 and Mfn2. More detailed ultrastructure analysis by transmission electron microscopy revealed aberrant mitochondrial structures with less and/or fragmented cristae and reduced mitochondrial matrix density as well as more punctate ER (endoplasmic reticulum) with noticeable dissociation of their ribosomes. The analysis of mitochondrial bioenergetics showed significantly reduced capacities in basal respiration and oxidative ATP turnover following p32 depletion. Furthermore, siRNA-mediated p32 knockdown resulted in differential stress-dependent effects on cell death, with enhanced cell death observed in the presence of hyperosmotic stress or cisplatin treatment, but decreased cell death in the presence of arsenite. Taken together, our studies highlight the critical contributions of the p32 protein to the morphology of mitochondria and ER under normal cellular conditions, as well as important roles of the p32 protein in cellular metabolism and various stress responses.
- Subjects :
- CCCP, carbonyl cyanide m-chlorophenylhydrazone
TBST, 10 mM Tris/HCl, pH 7.5, 150 mM NaCl and 0.1% Tween 20
PARP, poly(ADP-ribose) polymerase
Immunoblotting
MFN2
XTT, sodium 3′-[1-(phenylaminocarbonyl)-3,4-tetrazolium]-bis (4-methoxy-6-nitro) benzene sulfonic acid hydrate
gC1qR, receptor for globular head domains complement 1q
Mitochondrion
Biology
Endoplasmic Reticulum
Biochemistry
Mitochondrial apoptosis-induced channel
DMEM, Dulbecco’s modified Eagle’s medium
Mfn, mitofusin
Mitochondrial Proteins
mitochondrial morphology
Drp-1, dynamin-related protein 1
ER, endoplasmic reticulum
Adenosine Triphosphate
Humans
PJNK, phosphorylated c-Jun N-terminal kinase
OCR, oxygen consumption rate
TEM, transmission electron microscopy
Molecular Biology
Opa1, optical atrophy 1
Microscopy, Confocal
ECAR, extracellular acidification rate
LDH, lactate dehydrogenase
Endoplasmic reticulum
endoplasmic reticulum (ER) morphology
Cell Biology
stress response
Cell biology
Mitochondria
body regions
FCCP, carbonyl cyanide p-trifluoromethoxyphenylhydrazone
Mitochondrial permeability transition pore
mitochondrial fusion
mitochondrial metabolic activity
JNK, c-Jun N-terminal kinase
p32 Nm-terminus, N-terminus of mature p32 protein
DNAJA3
ATP–ADP translocase
RIPA, radioimmunoprecipitation assay
Carrier Proteins
HeLa Cells
Research Article
Subjects
Details
- ISSN :
- 14708728
- Volume :
- 453
- Issue :
- 3
- Database :
- OpenAIRE
- Journal :
- The Biochemical journal
- Accession number :
- edsair.doi.dedup.....1a446bf8770389164e0468b076d175f8