Multiple signals required for cyclic AMP-responsive element binding protein (CREB) binding protein interaction...

Area of Science:

• Immunology
• Molecular Biology
• Cell Signaling

Background:

• T lymphocyte activation is crucial for adaptive immunity.
• cAMP-responsive element binding protein (CREB) plays a key role in T cell function.
• Full T cell activation necessitates co-stimulation via CD3 and CD28 pathways.

Purpose of the Study:

• To investigate the molecular mechanisms underlying CREB activation by CD3/CD28 co-stimulation.
• To identify the specific signaling pathways involved in CREB-CREB-binding protein (CBP) interaction.
• To elucidate the role of different kinases in CREB phosphorylation and trans-activation.

Main Methods:

• Utilized a reporter system to monitor CREB-CBP interaction.
• Investigated the involvement of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), and calcium/calmodulin-dependent protein kinase (CaMK) IV.
• Performed reconstitution experiments to assess the impact of simultaneous kinase pathway activation.

Main Results:

• CREB binds to CBP exclusively upon simultaneous CD3 and CD28 engagement.
• CD3/CD28-mediated CREB-CBP interaction depends on ERK, p38 MAPK, and CaMK IV.
• Simultaneous activation of these three kinase pathways maximizes CREB-CBP interaction and CREB trans-activation.
• CD28 co-stimulation enhances the activation of p38 MAPK and CaMK IV, which are also stimulated by CD3.

Conclusions:

• Coordinated activation of multiple kinase pathways (ERK, p38 MAPK, CaMK IV) is required for optimal CREB activation.
• CD3/CD28 co-stimulation establishes a minimum activation threshold for CREB-CBP interaction.
• CD28 signaling potentiates the activation of key kinases involved in CREB signaling.