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Commitment and effector phases of the physiological cell death pathway elucidated with respect to Bcl-2 caspase, and cyclin-dependent kinase activities.

Abstract：

:Physiological cell deaths occur ubiquitously throughout biology and have common attributes, including apoptotic morphology with mitosis-like chromatin condensation and prelytic genome digestion. The fundamental question is whether a common mechanism of dying underlies these common hallmarks of death. Here we describe evidence of such a conserved mechanism in different cells induced by distinct stimuli to undergo physiological cell death. Our genetic and quantitative biochemical analyses of T- and B-cell deaths reveal a conserved pattern of requisite components. We have dissected the role of cysteine proteases (caspases) in cell death to reflect two obligate classes of cytoplasmic activities functioning in an amplifying cascade, with upstream interleukin-1beta-converting enzyme-like proteases activating downstream caspase 3-like caspases. Bcl-2 spares cells from death by punctuating this cascade, preventing the activation of downstream caspases while leaving upstream activity undisturbed. This observation permits an operational definition of the stages of the cell death process. Upstream steps, which are necessary but not themselves lethal, are modulators of the death process. Downstream steps are effectors of, and not dissociable from, actual death; the irreversible commitment to cell death reflects the initiation of this downstream phase. In addition to caspase 3-like proteases, the effector phase of death involves the activation in the nucleus of cell cycle kinases of the cyclin-dependent kinase (Cdk) family. Nuclear recruitment and activation of Cdk components is dependent on the caspase cascade, suggesting that catastrophic Cdk activity may be the actual effector of cell death. The conservation of the cell death mechanism is not reflected in the molecular identity of its individual components, however. For example, we have detected different cyclin-Cdk pairs in different instances of cell death. The ordered course of events that we have observed in distinct cases reflects essential thematic elements of a conserved sequence of modulatory and effector activities comprising a common pathway of physiological cell death.

journal_name

Mol Cell Biol

journal_title

Molecular and cellular biology

authors

Harvey KJ,Blomquist JF,Ucker DS

doi

10.1128/mcb.18.5.2912

subject

Has Abstract

pub_date

1998-05-01 00:00:00

pages

2912-22

issue

eissn

0270-7306

issn

1098-5549

journal_volume

pub_type

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Commitment and effector phases of the physiological cell death pathway elucidated with respect to Bcl-2 caspase, and cyclin-dependent kinase activities.