Related Experiment Video

Updated: Jun 28, 2026

Preparation of Primary Acute Lymphoblastic Leukemia Cells in Different Cell Cycle Phases by Centrifugal Elutriation
09:09

Preparation of Primary Acute Lymphoblastic Leukemia Cells in Different Cell Cycle Phases by Centrifugal Elutriation

Published on: November 10, 2017

Identification of a novel cyclin required for the intrinsic apoptosis pathway in lymphoid cells

M B Roig1, R Roset, L Ortet

  • 1Apoptosis Signalling Group, Cancer Research Programme, Institut Municipal d'Investigació Mèdica, Parc de Recerca Biomèdica de Barcelona, Dr. Aiguader, 88. 08003 Barcelona, Spain.

Cell Death and Differentiation
|October 18, 2008
PubMed

Insights

A novel cyclin, cyclin O, is essential for intrinsic apoptosis in lymphoid cells. Its synthesis triggers programmed cell death via caspase activation, independent of cell cycle or DNA damage responses.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Immunology

Background:

  • Intrinsic apoptosis pathways are crucial for cellular homeostasis and development.
  • Understanding the molecular triggers of apoptosis is key to developing targeted therapies.

Purpose of the Study:

  • To identify novel molecular regulators of intrinsic apoptosis in lymphoid cells.
  • To elucidate the role of cyclin O in apoptosis induction and its relationship with other cellular processes.

Main Methods:

  • Investigated cyclin O synthesis and complex formation with Cdk2 during apoptosis.
  • Analyzed cyclin O expression in vivo in mouse thymus and spleen.
  • Utilized shRNA to knock down cyclin O expression and assessed apoptosis induction.
  • Examined the impact of cyclin O on caspase activation and other cellular pathways.

Main Results:

  • Identified de novo synthesis of cyclin O as an early step in intrinsic apoptosis.
  • Cyclin O forms active complexes with Cdk2, preceding apoptosis induction.
  • Overexpression of cyclin O induces caspase-dependent apoptosis.
  • Knockdown of cyclin O inhibits glucocorticoid and DNA damage-induced apoptosis by preventing caspase activation.
  • Cyclin O-mediated apoptosis is distinct from CD95 death receptor pathways.

Conclusions:

  • Cyclin O plays a critical physiological role in inducing apoptosis in lymphoid cells.
  • Cyclin O functions independently of cell cycle, DNA damage checkpoints, or glucocorticoid transcriptional responses.
  • Cyclin O represents a novel target for modulating apoptosis in lymphoid malignancies and autoimmune diseases.

More Related Videos

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay12:26

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations10:54

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations

Published on: September 17, 2012

Related Concept Videos

The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
The Extrinsic Apoptotic Pathway01:17

The Extrinsic Apoptotic Pathway

The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
Anaphase Promoting Complex00:50

Anaphase Promoting Complex

The stepwise destruction of specific proteins is necessary for the progression and completion of the cell cycle. Such proteins are ubiquitinated by ubiquitin ligases and then subsequently destroyed by the proteasome. The SCF (Skp1/Cullin/F-box) and the anaphase-promoting complex (APC) are two important ubiquitin ligases involved in cell cycle progression. While SCF is active throughout the cell cycle, APC gets activated during metaphase to anaphase transition. Cdc20 or Cdh1 binds to APC and...
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...
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.
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.