Related Experiment Video

Updated: May 4, 2026

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry
08:07

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Published on: July 26, 2019

7.9K

Feedback regulation mediated by Bcl-2 and DARPP-32 regulates inositol 1,4,5-trisphosphate receptor phosphorylation

Ming-Jin Chang1, Fei Zhong, Andrew R Lavik

  • 1Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University School of Medicine and University Hospitals Case Medical Center, Cleveland, OH 44106.

Proceedings of the National Academy of Sciences of the United States of America
|January 8, 2014
PubMed

Insights

The Bcl-2 protein forms a complex with DARPP-32 and calcineurin on the InsP3R, creating a negative feedback loop that regulates calcium (Ca2+) release and prevents apoptosis. This mechanism is dysregulated in chronic lymphocytic leukemia.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Immunology

Background:

  • Bcl-2 protein inhibits apoptosis by interacting with the inositol 1,4,5-trisphosphate receptor (InsP3R), preventing calcium (Ca2+) release.
  • Dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) is an inhibitor of protein phosphatase 1 (PP1), regulated by protein kinase A (PKA) and calcineurin (CaN).

Purpose of the Study:

  • To investigate the interaction between Bcl-2, DARPP-32, and the InsP3R.
  • To elucidate the role of this complex in regulating calcium signaling and apoptosis.

Main Methods:

  • Co-immunoprecipitation assays to detect protein interactions.
  • Western blotting to assess protein phosphorylation levels.
  • Gene knockdown experiments (Bcl-2, DARPP-32) to evaluate the feedback mechanism.
  • Calcium imaging to measure Ca2+ flux.

Main Results:

  • Bcl-2 forms a complex with DARPP-32 and CaN on the InsP3R, creating a negative feedback loop.
  • This complex decreases PKA-mediated InsP3R phosphorylation, thereby reducing Ca2+ release.
  • Knockdown of Bcl-2 or DARPP-32 disrupts this feedback, leading to increased Ca2+ elevation and apoptosis.
  • High Bcl-2 levels in chronic lymphocytic leukemia cells exploit this mechanism to suppress B-cell receptor-induced Ca2+ signaling and apoptosis.

Conclusions:

  • A novel negative feedback mechanism involving Bcl-2, DARPP-32, CaN, and InsP3R regulates Ca2+ signaling and cell survival.
  • Dysregulation of this pathway contributes to the pathogenesis of chronic lymphocytic leukemia.
Keywords:
calciumcancerlymphocytesignal transductionsignaling

More Related Videos

Fluorescence-Based Measurements of Phosphatidylserine/Phosphatidylinositol 4-Phosphate Exchange Between Membranes08:49

Fluorescence-Based Measurements of Phosphatidylserine/Phosphatidylinositol 4-Phosphate Exchange Between Membranes

Published on: March 14, 2021

3.5K
Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death09:18

Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death

Published on: December 27, 2016

7.9K

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...
6.2K
PI3K/mTOR/AKT Signaling Pathway01:22

PI3K/mTOR/AKT Signaling Pathway

The mammalian target of rapamycin  (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1  (mTORC1) and mTOR complex 2  (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast,  mTORC2 consists of a...
5.1K
IP3/DAG Signaling Pathway01:11

IP3/DAG Signaling Pathway

Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the  phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and...
12.5K
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.
32.1K
Amplifying Signals via Enzymatic Cascade01:22

Amplifying Signals via Enzymatic Cascade

When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze...
15.3K
Receptor Downregulation in MVBs01:15

Receptor Downregulation in MVBs

Multivesicular bodies (MVBs) are mature endosomes that sort ubiquitinated proteins and then fuse with lysosomes to degrade the sorted proteins. Epidermal growth factor (EGF) and its receptor (EGFR) form a complex that can be internalized through endocytosis, sorted into an MVB, and later degraded.
The EGFR can initiate signaling pathways that  lead to cell proliferation, migration, and differentiation. Overexpression of EGFR  stimulates cells to proliferate. Excessive  EGFR...
2.0K