Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.62 (caspase-9)
 7,507 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cerebellar Purkinje neurons (PNs) are selectively vulnerable to AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepriopionic acid)-induced delayed neurotoxicity known as dark cell degeneration (DCD) that is expressed as cytoplasmic and nuclear condensation, neuron shrinkage, and failure of physiology. The present study was initiated to determine whether AMPA-receptor-induced DCD in PNs is associated with Bax translocation to the mitochondria, cytochrome C release from the mitochondria, changes in mitochondrial potential, and activation of representative initiator and executor caspases that include caspase-9, caspase-3, and caspase-7. AMPA consistently and rapidly hyperpolarized mitochondria as reflected by an increase in MitoTracker Red CMS Ros fluorescence. Increases in Bax immunoreactivity were quantitatively and temporally variable and Bax failed to localize to mitochondria. Additionally, we observed a marked increase in immunoreactivity of cytochrome C although its release from mitochondria was not apparent. Mitochondrial membrane hyperpolarization and increases in cytochrome C immunoreactivity preceded caspase activation. Immunohistochemical analyses revealed the active form of caspases-3 and -9 were markedly and significantly increased in PNs following 30 microM AMPA, and caspase-9 activation preceded caspase-3. Increases in active caspase-7 immunoreactivity were less frequently encountered in PNs. Thus DCD shares some characteristics of apoptotic programmed cell death, but lacks typical mitochondrial pathophysiology associated with classic apoptosis. These findings suggest that AMPA-induced DCD is a form of active PCD that lies on a spectrum between classical apoptosis and passive necrosis.
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PMID:AMPA-induced dark cell degeneration of cerebellar Purkinje neurons involves activation of caspases and apparent mitochondrial dysfunction. 1464 40

During the physiological process of PCD, the cell initiates a sequence of events culminating in the disintegration of the cell into small, membrane-bound apoptotic bodies. The intrinsic part of the PCD program arises from the mitochondria when it releases cytochrome c from the mitochondrial intermembrane space into the cytosol, forming the caspase-activating complex or apoptosome. The family of caspases is involved in the execution of genetically controlled PCD. Caspase-3 is expressed in normal and neoplastically transformed human cells and, like other caspases, is synthesized as an inactive, 32kDa proenzyme. Caspase-6 cleaves nuclear mitotic apparatus protein (NuMA) and mediates the shrinkage and fragmentation of cell nuclei. Caspase-8 is an initiation caspase that activates the caspase cascade during apoptosis, while caspase-9 is the initiator caspase in the caspase cascade in apoptotic normal and neoplastically transformed cells. During our immunocytochemical study, a sensitive, four-step, alkaline phosphatase conjugated antigen detection technique was employed. The results did in fact demonstrate the presence of high apoptotic activity within the cellular microenvironment of high-grade astrocytomas and glioblastomas. The observations identified cytoplasmic expression of caspase-3 and caspase-6 in more than 50 per cent of tumor cells, caspase-8 and caspase-9 in more than 10 per cent of tumor cells in high-grade anaplastic ASTR and glioblastoma. The immunocytochemical expression pattern in about 10 per cent of the tumor cells for caspase-3 and caspase-6 and about 1 to 5 per cent of the tumor cells for caspase-8 and caspase-9 demonstrated a translocation tendency from the cytoplasm to the cell nuclei in the apoptotic cells. This phenomenon may play an important role in these tumors' maintenance of immune privilege and evasion of immune attacks. We suggest that caspase-3, -6, -8 and -9 immunocytochemistry could have prognostic and immunotherapeutic significance in the treatment of these highly malignant glial tumors.
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PMID:Immunocytochemical detection of members of the caspase cascade of apoptosis in high-grade astrocytomas. 1552 99