DN2 thymocyte differentiation

Definition

Target type: biologicalprocess

The process in which a relatively unspecialized cell acquires the specialized features of a DN2 thymocyte. A DN2 thymocyte is a CD4-,CD8- thymocyte that is also CD44+,CD25-. [GO_REF:0000086, GOC:dph, GOC:TermGenie, PMID:25398325]

DN2 thymocyte differentiation is a crucial stage in T cell development, occurring in the thymus. It is characterized by the expression of CD44 and CD25, but not CD4 or CD8, giving DN2 thymocytes their unique surface marker profile. This stage follows the DN1 stage and precedes the DN3 stage.

During DN2 differentiation, several key events occur:

1. **TCRβ Gene Rearrangement and Selection:** The DN2 stage is marked by the rearrangement of the TCRβ gene locus. This process involves a series of DNA recombination events that generate a diverse repertoire of TCRβ chains. Successful TCRβ rearrangement results in the expression of a functional TCRβ protein.

2. **Pre-TCR Complex Formation:** The newly synthesized TCRβ chain pairs with the pre-Tα chain, forming the pre-TCR complex. This complex associates with CD3 proteins and signals to the cell, halting further TCRβ rearrangement.

3. **Positive Selection:** The pre-TCR complex plays a critical role in positive selection, ensuring that only thymocytes with functional TCRβ chains capable of interacting with self-MHC molecules survive. This process occurs in the thymic cortex.

4. **DN2 to DN3 Transition:** Successful pre-TCR signaling triggers the downregulation of CD25 and the upregulation of CD4 and CD8, marking the transition to the DN3 stage.

5. **Commitment to the αβ Lineage:** DN2 thymocytes are committed to the αβ lineage of T cell development.

Overall, the DN2 stage is characterized by TCRβ gene rearrangement, pre-TCR complex formation, and the initiation of positive selection, all culminating in the transition to the DN3 stage and the continued development of αβ T cells.'
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Proteins (1)

Compounds (10)