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Published on: April 24, 2021
p27 small interfering RNA induces cell death through elevating cell cycle activity in cultured cortical neurons: a
H Akashiba1, N Matsuki, N Nishiyama
1Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Abstract:
Recent research has demonstrated that cell cycle-associated molecules are activated in multiple forms of cell death in mature neurons, and raised a hypothesis that unscheduled cell cycle activity leads to neuronal cell death. But there is little evidence that changes in endogenous level of these molecules are causally associated with neuronal cell death. Here we transfected small interfering RNA (siRNA) targeting cyclin-dependent kinase (CDK) inhibitor p27, which plays an important role in cell cycle arrest at G1-S phase, into cultured cortical neurons. Transfection of p27 siRNA reduced neuronal viability in a time-dependent manner. p27 siRNA induced phosphorylation of retinoblastoma protein (Rb), a marker of cell cycle progression at late G1 phase. Moreover, phosphorylation of Rb and neuronal cell death provoked by p27 siRNA were abrogated by pharmacological CDK inhibitors, olomoucine and purvalanol A. Our data demonstrate that a decrease in endogenous p27 induces neuronal cell death through elevating cell cycle activity.
Insights
Reducing cyclin-dependent kinase inhibitor p27 in neurons triggers cell death by reactivating the cell cycle. This study provides causal evidence linking cell cycle activity to neuronal death.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Cell cycle-associated molecules are activated during neuronal cell death.
- A hypothesis suggests unscheduled cell cycle activity causes neuronal death.
- Evidence for a causal link between endogenous molecule levels and neuronal death is limited.
Purpose of the Study:
- To investigate the causal role of the cell cycle inhibitor p27 in neuronal cell death.
- To determine if reduced p27 levels lead to cell cycle re-entry and subsequent neuronal death.
Main Methods:
- Cultured cortical neurons were transfected with small interfering RNA (siRNA) targeting p27.
- Neuronal viability was assessed over time.
- Cell cycle progression was monitored by retinoblastoma protein (Rb) phosphorylation.
- Pharmacological cyclin-dependent kinase (CDK) inhibitors (olomoucine, purvalanol A) were used to block CDK activity.
Main Results:
- p27 siRNA transfection reduced neuronal viability in a time-dependent manner.
- p27 depletion induced Rb phosphorylation, indicating cell cycle progression.
- CDK inhibitors blocked Rb phosphorylation and neuronal cell death caused by p27 siRNA.
Conclusions:
- A decrease in endogenous p27 levels causes neuronal cell death.
- This cell death occurs through the re-activation of the cell cycle.
- Targeting cell cycle regulators offers potential therapeutic strategies for neuronal protection.
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