Protein kinases selectively modulate apoptosis in the developing retina in vitro

Area of Science:

• Neuroscience
• Developmental Biology
• Cell Biology

Background:

• Developing retinas exhibit distinct programmed cell death (apoptosis) mechanisms.
• Ganglion cell apoptosis (RGCs) after axotomy requires protein synthesis.
• Neuroblastic layer (NBL) apoptosis is induced by protein synthesis inhibition, suggesting post-translational modifications are key.

Purpose of the Study:

• Investigate the role of protein kinases in retinal apoptosis.
• Determine the effects of cAMP and cGMP signaling on programmed cell death in retinal explants.
• Elucidate layer-specific regulation of apoptosis in the developing retina.

Main Methods:

• Utilized in vitro retinal explants from newborn rats.
• Administered forskolin and 8-Br-cAMP to modulate intracellular cAMP levels.
• Applied 8-Br-cGMP, zaprinast, IBMX, Ro-201724, H89, TPA, bisindolylmaleimide, and 2-aminopurine to target specific signaling pathways and kinases.

Main Results:

• Increased cAMP levels (forskolin, 8-Br-cAMP) prevented NBL apoptosis but not RGC apoptosis.
• cAMP-phosphodiesterase inhibitors (IBMX, Ro-201724) also protected NBL cells.
• The cAMP-dependent protein kinase inhibitor H89 partially reversed the protective effects of cAMP modulators in the NBL.
• Protein kinase inhibitor 2-aminopurine (2-AP) prevented RGC apoptosis and induced NBL apoptosis.
• Forskolin counteracted 2-AP-induced NBL apoptosis, while TPA had no effect.

Conclusions:

• Modulation of cAMP-dependent protein kinase activity selectively impacts NBL apoptosis.
• Protein kinases sensitive to 2-aminopurine play a role in RGC apoptosis.
• Distinct protein kinase pathways regulate apoptosis in different retinal cell layers during development.