Related Experiment Video

Updated: Aug 8, 2026

A High-content Imaging Workflow to Study Grb2 Signaling Complexes by Expression Cloning
10:52

A High-content Imaging Workflow to Study Grb2 Signaling Complexes by Expression Cloning

Published on: October 30, 2012

Egr-1 expression in surface Ig-mediated B cell activation. Kinetics and association with protein kinase C activation

V L Seyfert1, S McMahon, W Glenn

  • 1Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104-6082.

Journal of Immunology (Baltimore, Md. : 1950)
|December 1, 1990
PubMed

Insights

The immediate/early gene Egr-1 is rapidly expressed in B lymphocytes upon antigen receptor activation. Its induction is linked to protein kinase C signaling, not calcium levels, influencing gene expression changes.

Area of Science:

  • Immunology
  • Molecular Biology
  • Cell Signaling

Background:

  • Immediate/early genes like Egr-1 play crucial roles in cellular responses to external stimuli.
  • Egr-1 encodes a transcription factor involved in coupling receptor signals to gene expression.
  • B lymphocyte activation involves complex signaling pathways initiated by the B cell antigen receptor.

Purpose of the Study:

  • To investigate the expression pattern of the Egr-1 gene in murine B lymphocytes following antigen receptor stimulation.
  • To elucidate the specific signaling pathways, particularly protein kinase C and calcium signaling, that regulate Egr-1 induction in B cells.
  • To understand the role of Egr-1 as a mediator of B cell activation and gene expression changes.

Main Methods:

  • Murine B lymphocytes were stimulated with anti-receptor antibodies to induce receptor crosslinking.
  • Quantitative analysis of Egr-1 mRNA and protein expression over time.
  • Inhibition studies using actinomycin D to assess dependence on new protein synthesis.
  • Pharmacological manipulation using protein kinase C activators (PMA, SC-9) and inhibitors (H7, sangivamycin, staurosporin).
  • Investigation of Egr-1 induction in response to elevated intracellular free calcium levels.
  • Preliminary promoter mapping to identify cis-regulatory elements involved in Egr-1 regulation.

Main Results:

  • Egr-1 mRNA expression was rapidly and transiently induced by anti-receptor antibodies, returning to basal levels by 6 hours.
  • Egr-1 protein expression was more sustained, detectable up to 12 hours.
  • Egr-1 induction was independent of de novo protein synthesis and sensitive to actinomycin D, indicating a primary response.
  • Egr-1 mRNA induction was not observed upon elevation of intracellular free calcium.
  • Pharmacological activation of protein kinase C (PKC) with PMA and SC-9 mimicked the kinetics of anti-receptor antibody-induced Egr-1 expression.
  • PKC inhibitors (H7, sangivamycin, staurosporin) blocked anti-receptor antibody-induced Egr-1 expression.
  • Preliminary promoter analysis suggested that PMA and anti-receptor antibody signaling converge on common cis-regulatory elements.

Conclusions:

  • Egr-1 is a key immediate/early gene rapidly induced in B lymphocytes upon antigen receptor activation.
  • The signaling pathway for Egr-1 induction in B cells is primarily mediated by protein kinase C, not intracellular calcium.
  • Egr-1 acts as a crucial link between B cell antigen receptor stimulation and downstream gene expression changes, potentially influencing cell cycle progression.

More Related Videos

A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide11:02

A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide

Published on: October 18, 2014

Oligomerization Dynamics of Cell Surface Receptors in Living Cells by Total Internal Reflection Fluorescence Microscopy Combined with Number and Brightness Analysis10:43

Oligomerization Dynamics of Cell Surface Receptors in Living Cells by Total Internal Reflection Fluorescence Microscopy Combined with Number and Brightness Analysis

Published on: November 6, 2019

Related Concept Videos

Amplifying Signals via Second Messengers01:15

Amplifying Signals via Second Messengers

Many receptor binding ligands are hydrophilic; they do not cross the cell membrane but bind to cell-surface receptors. Thus, their message must be relayed by second messengers present in the cell cytoplasm. There are several second messenger pathways, each with its own way of relaying information. For example, the G protein-coupled receptors can activate both phosphoinositol and cyclic AMP (cAMP) second messenger pathways. The phosphoinositol pathway is active when the receptor induces...
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 the...
Activation and Inactivation of G Proteins01:22

Activation and Inactivation of G Proteins

Heterotrimeric G proteins are guanine nucleotide-binding proteins. As the name suggests, heterotrimeric G proteins are composed of three subunits: alpha, beta, and gamma. They remain GDP-bound or GTP-bound inside the cells and switch between inactive/active states. The Gα subunit possesses the nucleotide-binding pocket that binds guanine nucleotides and switches between GDP or GTP-bound states. In contrast, the Gꞵ and Gγ subunits are always bound together with high affinity and are together...
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 produces two-second...
Activation of Integrins01:15

Activation of Integrins

Integrins bind ligands and transmit information from outside the cell to inside or vice-versa through an "outside-in signaling" or "inside-out signaling."
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
Intracellular Signaling Affects Focal Adhesions01:17

Intracellular Signaling Affects Focal Adhesions

Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...