T cell proliferation

Definition

Target type: biologicalprocess

The expansion of a T cell population by cell division. Follows T cell activation. [GOC:jl]

T cell proliferation is a critical process in the adaptive immune response, enabling the expansion of T cells that recognize specific antigens. This process is tightly regulated and involves a complex interplay of signaling pathways, transcription factors, and cell cycle checkpoints.

**1. Antigen Recognition and Activation:**

* T cell receptor (TCR) on the surface of T cells recognizes specific antigens presented by antigen-presenting cells (APCs) in the context of major histocompatibility complex (MHC) molecules.
* TCR engagement initiates signaling cascades involving tyrosine kinases, such as Lck and ZAP-70.

**2. Signaling Cascades and Transcription Factor Activation:**

* Signaling pathways downstream of TCR activation lead to the activation of transcription factors, including NF-κB, AP-1, and NFAT.
* These transcription factors induce the expression of genes involved in T cell proliferation, survival, and effector function.

**3. Cytokine Signaling:**

* Activated T cells produce and respond to cytokines, such as interleukin-2 (IL-2), which play a crucial role in promoting T cell proliferation.
* IL-2 binds to its receptor on T cells, triggering a signaling pathway that activates the transcription factor STAT5.
* STAT5 promotes the expression of genes involved in cell cycle progression, including cyclins and cyclin-dependent kinases (CDKs).

**4. Cell Cycle Progression:**

* Activated T cells enter the cell cycle, progressing through G1, S, G2, and M phases.
* Cyclins and CDKs regulate the transition between different phases of the cell cycle, ensuring proper DNA replication and cell division.

**5. Differentiation and Effector Function:**

* Proliferating T cells differentiate into effector T cells, such as cytotoxic T lymphocytes (CTLs) or helper T cells.
* Effector T cells carry out specific functions to eliminate pathogens or regulate immune responses.

**6. Regulation and Homeostasis:**

* T cell proliferation is tightly regulated to prevent excessive immune responses and maintain immune homeostasis.
* Regulatory T cells (Tregs) suppress T cell proliferation and prevent autoimmunity.
* Apoptosis pathways also play a role in eliminating activated T cells after antigen clearance.

**Overall, T cell proliferation is a multistep process involving antigen recognition, signaling pathways, transcription factor activation, cytokine signaling, cell cycle progression, and differentiation into effector cells. This process is crucial for mounting effective immune responses against pathogens and maintaining immune homeostasis.'
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Proteins (16)

Compounds (370)