Type

Other / n/a

Authors

Jochen HM Prehn
Manus W Ward
Michael J Courtney
Ina Woods
Heiko Düssmann
Liam P Tuffy
Helena Bonner
Beatrice D'Orsi

Subjects

Biochemistry

Topics
bcl 2 associated x protein calpain physiology mice inbred c57bl cell line tumor dipeptides excitatory amino acid agonists apoptosis mice 129 strain animals 129 strain cells cultured mice cell line cells knockout humans hippocampus cultured mice knockout n methylaspartate female tumor pregnancy inbred c57bl organ culture techniques physics

Calpains are downstream effectors of bax-dependent excitotoxic apoptosis. (2012)

Abstract Excitotoxicity resulting from excessive Ca(2+) influx through glutamate receptors contributes to neuronal injury after stroke, trauma, and seizures. Increased cytosolic Ca(2+) levels activate a family of calcium-dependent proteases with papain-like activity, the calpains. Here we investigated the role of calpain activation during NMDA-induced excitotoxic injury in embryonic (E16-E18) murine cortical neurons that (1) underwent excitotoxic necrosis, characterized by immediate deregulation of Ca(2+) homeostasis, a persistent depolarization of mitochondrial membrane potential (Δψ(m)), and insensitivity to bax-gene deletion, (2) underwent excitotoxic apoptosis, characterized by recovery of NMDA-induced cytosolic Ca(2+) increases, sensitivity to bax gene deletion, and delayed Δψ(m) depolarization and Ca(2+) deregulation, or (3) that were tolerant to excitotoxic injury. Interestingly, treatment with the calpain inhibitor calpeptin, overexpression of the endogenous calpain inhibitor calpastatin, or gene silencing of calpain protected neurons against excitotoxic apoptosis but did not influence excitotoxic necrosis. Calpeptin failed to exert a protective effect in bax-deficient neurons but protected bid-deficient neurons similarly to wild-type cells. To identify when calpains became activated during excitotoxic apoptosis, we monitored calpain activation dynamics by time-lapse fluorescence microscopy using a calpain-sensitive Förster resonance energy transfer probe. We observed a delayed calpain activation that occurred downstream of mitochondrial engagement and directly preceded neuronal death. In contrast, we could not detect significant calpain activity during excitotoxic necrosis or in neurons that were tolerant to excitotoxic injury. Oxygen/glucose deprivation-induced injury in organotypic hippocampal slice cultures confirmed that calpains were specifically activated during bax-dependent apoptosis and in this setting function as downstream cell-death executioners.
Collections Ireland -> Royal College of Surgeons in Ireland -> Physiology and Medical Physics Articles
Ireland -> Royal College of Surgeons in Ireland -> Department of Physiology and Medical Physics

Full list of authors on original publication

Jochen HM Prehn, Manus W Ward, Michael J Courtney, Ina Woods, Heiko Düssmann, Liam P Tuffy, Helena Bonner, Beatrice D'Orsi

Experts in our system

1
Jochen H M Prehn
Royal College of Surgeons in Ireland
Total Publications: 206
 
2
Ina Woods
Royal College of Surgeons in Ireland
Total Publications: 16
 
3
Heiko Düssmann
Royal College of Surgeons in Ireland
Total Publications: 45
 
4
Liam P Tuffy
Royal College of Surgeons in Ireland
Total Publications: 13
 
5
Helena P Bonner
Royal College of Surgeons in Ireland
Total Publications: 15
 
6
Beatrice D'Orsi
Royal College of Surgeons in Ireland
Total Publications: 14