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Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk1
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CDK7 regulates the mitochondrial localization of a tail-anchored proapoptotic protein, Hid

Jun Morishita1, Min-Ji Kang1, Kevin Fidelin1

  • 1Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA.

Cell Reports
|December 24, 2013
PubMed

Insights

The cdk7 complex regulates Hid protein

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The mitochondrial outer membrane is crucial for apoptosis regulation.
  • Tail-anchored proteins like Hid require specific sequences for mitochondrial insertion.
  • The regulation of mitochondrial localization by cytosolic proteins is not fully understood.

Purpose of the Study:

  • To investigate the role of cytosolic proteins in regulating the mitochondrial localization of Hid.
  • To identify novel regulators of apoptosis.
  • To elucidate the function of cdk7 in apoptosis.

Main Methods:

  • In vivo RNAi screen to identify genes involved in cell death.
  • Analysis of a hypomorphic cdk7 mutant.
  • Mitochondrial localization assays for Hid.
  • In vitro binding assays with inhibitors of apoptosis (IAPs).

Main Results:

  • The cdk7 complex was identified as a regulator of Hid mitochondrial localization and apoptosis induction.
  • A hypomorphic cdk7 mutant suppressed apoptosis without affecting transcription or cell-cycle progression.
  • In the cdk7 mutant, Hid failed to localize to mitochondria and bind to IAPs.
  • CDK7 has a newly identified function in promoting apoptosis.

Conclusions:

  • CDK7 plays a novel role in apoptosis by regulating the mitochondrial localization and IAP binding of Hid.
  • This finding reveals a new mechanism coupling mitochondrial targeting and protein interactions in apoptosis.
  • CDK7's function extends beyond its known roles in transcription and cell-cycle progression.

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