Final answer:
B cell activation involves intracellular signaling pathways leading to NF-AT and other TFs, which are crucial for gene transcription essential for B cell functions. Following BCR signaling, NF-AT transcription factors are activated by calcineurin after calcium signaling, and translocate to the nucleus to drive gene expression related to B cell differentiation into plasma cells and memory cells.
Step-by-step explanation:
Upon B cell activation, several intracellular signaling pathways are triggered eventually leading to the activation of transcription factors (TFs) such as NF-AT (Nuclear Factor of Activated T-cells), which are critical for initiating the transcription of genes necessary for B cell differentiation and function.
When a B cell encounters and engulfs an antigen, it presents fragments on its surface to helper T cells, which in turn signal the B cell to differentiate into a plasma cell through the release of cytokines. This interaction and subsequent signaling involve linked recognition between B cells and helper T cells specific to the same antigen.
In T cell-dependent activation, B cell receptor (BCR) signaling leads to a series of downstream events, termed a signaling pathway or cascade, involving second messengers, enzyme activation, and the phosphorylation of target proteins.
Moreover, there is T cell-independent activation, which is less complex and results from direct recognition of antigens with repetitive structures by BCRs. However, this lacks the potency and memory capabilities of T cell-dependent responses.
Active NF-AT proteins translocate to the nucleus, where they collaborate with other TFs to induce genes critical for B cell responses, such as those involved in cytokine production, survival, and differentiation into plasma cells and memory B cells.