Heat shock and tumor necrosis factor-α induce apoptosis in bovine preimplantation embryos through a caspase-9-dependent mechanism
Open Access
- 1 June 2007
- journal article
- Published by Bioscientifica in Reproduction
- Vol. 133 (6), 1129-1137
- https://doi.org/10.1530/rep-06-0307
Abstract
Heat shock and tumor necrosis factor-α (TNF-α) induce apoptosis through different mechanisms, with heat shock acting to cause mitochondrial depolarization and caspase-9 activation, while TNF-α acts through a receptor-mediated process to activate caspase-8. In some cells, however, TNF-α can also cause mitochondrial depolarization and caspase-9 activation. In the present study, we tested the hypothesis that heat shock at 41 °C and TNF-α induce apoptosis in bovine preimplantation embryos through a caspase-9-dependent mechanism. Treatment of embryos with either heat shock (41 °C) or TNF-α increased the proportion of blastomeres that were TUNEL positive and the proportion of embryos exhibiting elevated caspase-9 activity. Furthermore, the caspase-9 inhibitor, z-LEHD-fmk, blocked the increase in TUNEL-positive nuclei caused by both heat shock and TNF-α. For embryos at day 6 after insemination, for example, the percent of blastomeres positive for TUNEL was 3.6% for control embryos, 11.1% for embryos cultured at 41 °C, and 15.1% for embryos cultured with 10 ng/ml TNF-α. In the presence of z-LEHD-fmk, the percent of cells positive for TUNEL was 3.7% for control embryos, 6.1% for embryos cultured at 41 °C, and 8% for embryos cultured with 10 ng/ml TNF-α. Although TNF-α did not cause a measurable increase in caspase-8 activity, there was a tendency (P= 0.07) for treatment of embryos with z-IETD-fmk, an inhibitor of caspase-8, to partly reduce the magnitude of the increase in TUNEL-positive cells caused by TNF-α. The percent of cells that were TUNEL positive was increased by TNF-α from 9.7 to 19.7% in the absence of inhibitor and from 13.0 to 15.6% in the presence of z-IETD-fmk. Results indicate that induction of apoptosis by both heat shock and TNF-α involve activation of caspase-9-dependent pathways. It is likely that TNF-α also activates apoptotic pathways involving caspase-8 but that the degree of activation is small and caspase-9-dependent pathways are required for full activation of apoptosis.Keywords
This publication has 25 references indexed in Scilit:
- Differential caspase‐9‐dependent signaling pathway between tumor necrosis factor receptor‐ and Fas‐mediated hepatocyte apoptosis in miceLiver International, 2005
- Chronological Appearance of Apoptosis in Bovine Embryos Reconstructed by Somatic Cell Nuclear Transfer from Quiescent Granulosa CellsReproduction in Domestic Animals, 2005
- Thermotolerance induced at a mild temperature of 40°C protects cells against heat shock‐induced apoptosisJournal of Cellular Physiology, 2005
- `The stress of dying': the role of heat shock proteins in the regulation of apoptosisJournal of Cell Science, 2004
- Mastitis and Fertility in Cattle – Possible Involvement of Inflammation or Immune Activation in Embryonic Mortality*American Journal of Reproductive Immunology, 2004
- Caspase-9 is activated in a cytochrome c-independent manner early during TNFα-induced apoptosis in murine cellsCell Death & Differentiation, 2003
- Developmental changes in inhibitory effects of arsenic and heat shock on growth of pre‐implantation bovine embryosMolecular Reproduction and Development, 2002
- Teratogen-Induced Activation of Caspase-9 and the Mitochondrial Apoptotic Pathway in Early Postimplantation Mouse EmbryosToxicology and Applied Pharmacology, 2002
- Cytochrome c Release from Mitochondria of Early Postimplantation Murine Embryos Exposed to 4-Hydroperoxycyclophosphamide, Heat Shock, and StaurosporineToxicology and Applied Pharmacology, 2000
- Inhibition of Human Caspases by Peptide-based and Macromolecular InhibitorsJournal of Biological Chemistry, 1998