Caspase-Dependent and Caspase-Independent Pathways Are Involved in Cadmium-Induced Apoptosis in Primary Rat Proximal Tubular Cell Culture

Gang Liu; Hui Zou; Tongwang Luo; Mengfei Long; Jianchun Bian; Xuezhong Liu; Jianhong Gu; Yan Yuan; Ruilong Song; Yi Wang; Jiaqiao Zhu; Zongping Liu

doi:10.1371/journal.pone.0166823

Caspase-Dependent and Caspase-Independent Pathways Are Involved in Cadmium-Induced Apoptosis in Primary Rat Proximal Tubular Cell Culture

PLoS One. 2016 Nov 18;11(11):e0166823. doi: 10.1371/journal.pone.0166823. eCollection 2016.

Authors

Affiliation

¹ College of Veterinary Medicine, Yangzhou University, and Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, and Jiangsu Key Laboratory of Zoonosis, Yangzhou, Jiangsu, PR China.

Abstract

We designed this study to investigate whether cadmium induces caspase-independent apoptosis and to investigate the relationship between the caspase-dependent and caspase-independent apoptotic pathways. Cadmium (1.25-2.5 μM) induced oxidative stress in rat proximal tubular (rPT) cells, as seen in the reactive oxygen species levels; N-acetylcysteine prevented this. Cyclosporin A (CsA) prevented mitochondrial permeability transition pore opening and apoptosis; there was mitochondrial ultrastructural disruption, mitochondrial cytochrome c (cyt c) translocation to the cytoplasm, and subsequent caspase-9 and caspase-3 activation. Z-VAD-FMK prevented caspase-3 activation and apoptosis and decreased BNIP-3 (Bcl-2/adenovirus E1B 19-kDa interacting protein 3) expression levels and apoptosis-inducing factor/endonuclease G (AIF/Endo G) translocation. Simultaneously, cadmium induced prominent BNIP-3 expression in the mitochondria and cytoplasmic AIF/Endo G translocation to the nucleus. BNIP-3 silencing significantly prevented AIF and Endo G translocation and decreased the apoptosis rate, cyt c release, and caspase-9 and caspase-3 activation. These results suggest that BNIP-3 is involved in the caspase-independent apoptotic pathway and is located upstream of AIF/Endo G; both the caspase-dependent and caspase-independent pathways are involved in cadmium-induced rPT cell apoptosis and act synergistically.

MeSH terms

Animals
Apoptosis / drug effects*
Cadmium / pharmacology*
Caspase Inhibitors / pharmacology
Caspases / metabolism*
Cytochromes c / metabolism
Endodeoxyribonucleases / metabolism
Epithelial Cells / drug effects*
Epithelial Cells / metabolism*
Gene Silencing
Kidney Tubules, Proximal / drug effects*
Kidney Tubules, Proximal / metabolism*
Membrane Proteins / genetics
Mitochondria / drug effects
Mitochondria / metabolism
Mitochondrial Membrane Transport Proteins / metabolism
Mitochondrial Permeability Transition Pore
Mitochondrial Proteins / genetics
Oxidative Stress / drug effects
Primary Cell Culture
Rats
Reactive Oxygen Species / metabolism
Signal Transduction / drug effects

Substances

BNIP3 protein, rat
Caspase Inhibitors
Membrane Proteins
Mitochondrial Membrane Transport Proteins
Mitochondrial Permeability Transition Pore
Mitochondrial Proteins
Reactive Oxygen Species
Cadmium
Cytochromes c
Endodeoxyribonucleases
endonuclease G
Caspases

Grants and funding

This work was supported by the National Natural Science Foundation of China (No. 31101866, No. 31372495, No. 31502128 and No. 31302058), Jiangsu Provincial Natural Science Foundation of China (BK20150447) and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). We state that the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.