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Related Concept Videos

T Cell Activation and Clonal Selection01:22

T Cell Activation and Clonal Selection

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T cells are integral to our adaptive immune system, recognizing and effectively responding to foreign antigens. T cell activation and clonal selection are pivotal in orchestrating this immune response. This article elucidates these mechanisms, detailing the roles of cluster of differentiation (CD) markers, major histocompatibility complex (MHC) molecules, costimulatory signals, and the process of clonal selection.
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T Cell Types and Functions01:24

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When T cells with CD4 markers are activated, they give rise to two types of effector cells: helper T cells and regulatory T cells. Meanwhile, T cells with CD8 markers differentiate into effector cytotoxic T cells. The differentiation of CD4 T cells into helper T cell subsets, such as Th1, Th2, and Th17 cells, is dependent on the antigen type, antigen-presenting cell, and regulatory cytokines.
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Inhibition of Cdk Activity02:34

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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...
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Eukaryotic Transcription Inhibitors

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Certain biochemical processes, such as embryonic development and cell growth regulation, depend on the repression of specific genes. DNA binding proteins known as eukaryotic transcription inhibitors regulate the repression of gene expression in eukaryotes. The presence of these inhibitors at the required location and time in the cell is triggered by the presence of hormones and additional signals from other cells.
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Feedback Inhibition00:46

Feedback Inhibition

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Biochemical reactions are occurring constantly in cells, converting starting substances to different products, usually with the help of enzymes that speed the reactions. Without enzymes, it would take far too long for most reactions to occur to be useful to the cell!
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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...
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Phenotypic and Functional Analysis of Activated Regulatory T Cells Isolated from Chronic Lymphocytic Choriomeningitis Virus-infected Mice
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Phenotypic and Functional Analysis of Activated Regulatory T Cells Isolated from Chronic Lymphocytic Choriomeningitis Virus-infected Mice

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Enhancing and inhibitory motifs regulate CD4 activity.

Mark S Lee1, Peter J Tuohy1, Caleb Y Kim1

  • 1Department of Immunobiology, The University of Arizona College of Medicine, Tucson, United States.

Elife
|July 21, 2022
PubMed
Summary
This summary is machine-generated.

Evolutionary selection shaped CD4 protein motifs to optimize T cell responses to peptide-MHCII. These motifs balance activating and inhibitory signals, influencing CD4

Keywords:
CD4T cellTCRactivationevolutionevolutionary biologyimmunologyinflammationmousesignaling

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Area of Science:

  • Immunology
  • Evolutionary Biology
  • Molecular Biology

Background:

  • CD4+ T cells are crucial for adaptive immunity, recognizing peptide antigens presented by MHCII molecules.
  • The CD4 co-receptor plays a vital role in T cell receptor (TCR)-CD3 complex signaling during antigen recognition.
  • Understanding CD4's structural and functional evolution provides insights into immune receptor mechanisms.

Purpose of the Study:

  • To investigate the evolutionary pressures on CD4 protein motifs.
  • To elucidate how CD4 motifs modulate T cell responses to peptide-MHCII (pMHCII).
  • To clarify the role of CD4-Lck interactions in pMHCII responses.

Main Methods:

  • Comparative evolutionary analysis of CD4 sequences across jawed vertebrates.
  • Functional studies examining the impact of specific CD4 motifs on pMHCII responses.
  • Investigation of CD4 interactions with the Src kinase Lck.

Main Results:

  • Purifying selection has conserved specific motifs in CD4's extracellular, transmembrane, and intracellular domains.
  • These CD4 motifs enhance pMHCII responses and covary with inhibitory intracellular residues.
  • CD4-Lck interaction importance is linked to an inhibitory motif and membrane compartmentalization.

Conclusions:

  • Evolutionary conserved CD4 motifs fine-tune T cell activation by balancing signaling pathways.
  • CD4's functional complexity arises from interplay between activating, inhibitory, and localization motifs.
  • Findings impact our understanding of transmembrane receptor evolution and biomimetic design.