Related Experiment Video

Updated: Aug 25, 2026

Intracellular Refolding Assay
07:18

Intracellular Refolding Assay

Published on: January 24, 2012

Hsp27 as a negative regulator of cytochrome C release

Catherine Paul1, Florence Manero, Sandrine Gonin

  • 1Centre de Génétique Moléculaire et Cellulaire, CNRS-UMR-5534, Université Claude Bernard Lyon I, F-69622 Villeurbanne, France.

Molecular and Cellular Biology
|January 11, 2002
PubMed

Insights

Heat shock protein 27 (Hsp27) protects cells from apoptosis by stabilizing the F-actin cytoskeleton, which delays cytochrome c release from mitochondria. This mechanism is crucial for regulating cell death pathways.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Heat shock protein 27 (Hsp27) is known to protect against apoptosis via interaction with cytosolic cytochrome c.
  • The precise molecular mechanisms underlying Hsp27's protective role, particularly its influence on mitochondrial events, require further elucidation.

Purpose of the Study:

  • To investigate the role of Hsp27 expression levels in modulating cytochrome c release from mitochondria during apoptosis.
  • To explore the potential link between Hsp27's effect on F-actin cytoskeleton integrity and its anti-apoptotic function.
  • To identify the upstream signaling events regulated by Hsp27 in response to apoptotic stimuli.

Main Methods:

  • Utilized murine cell lines with varying Hsp27 expression levels.
  • Assessed cytochrome c release, procaspase 3 activation, and Bid intracellular redistribution.
  • Investigated the impact of F-actin cytoskeleton modulators (cytochalasin D, phalloidin) on apoptosis signaling.

Main Results:

  • Hsp27 expression level-dependently inhibits cytochrome c release from mitochondria.
  • Decreased Hsp27 sensitizes cells to apoptosis by accelerating cytochrome c release and caspase activation.
  • Hsp27's protective effect is linked to its ability to maintain F-actin integrity, influencing Bid redistribution upstream of mitochondria.

Conclusions:

  • Hsp27 acts as an expression-dependent regulator of apoptosis, interfering with signals upstream of mitochondria.
  • The integrity of the F-actin cytoskeleton, modulated by Hsp27, plays a critical role in regulating cytochrome c release.
  • Hsp27's anti-apoptotic function involves protecting the cytoskeleton, thereby delaying mitochondrial apoptotic signaling.

More Related Videos

Defining Hsp33's Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry10:24

Defining Hsp33's Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry

Published on: June 7, 2018

Exploring Sequence Space to Identify Binding Sites for Regulatory RNA-Binding Proteins11:34

Exploring Sequence Space to Identify Binding Sites for Regulatory RNA-Binding Proteins

Published on: August 9, 2019

Related Concept Videos

Positive Regulator Molecules01:45

Positive Regulator Molecules

To consistently produce healthy cells, the cell cycle—the process that generates daughter cells—must be precisely regulated.
Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
Covalently Linked Protein Regulators02:04

Covalently Linked Protein Regulators

Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
Positive Regulator Molecules02:39

Positive Regulator Molecules

Mitotic cell division results in daughter cells that exactly resemble the parent cell. However, errors in the DNA replication or distribution of genetic material may lead to genetic mutations that may be passed down to every new cell formed from the resulting abnormal cell. Propagation of such mutant cells is restricted through checkpoint mechanisms present at different stages of the cell cycle. These checkpoints involve regulator molecules that either promote or demote cell cycle events.
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Allosteric Proteins-ATCase01:19

Allosteric Proteins-ATCase

Binding sites linkages can regulate a protein's function.  For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to  N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...