Protein kinase C activity and substrate (F1/GAP-43) phosphorylation in developing cat visual cortex.

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Molecular Neuroscience

Background:

• Protein kinase C (PKC) and its substrates, like F1/GAP-43, are linked to synaptic plasticity and long-term potentiation (LTP).
• Understanding the role of PKC in visual cortex development during its critical period is crucial for comprehending plasticity mechanisms.

Purpose of the Study:

• To investigate the involvement of PKC and its substrates in visual cortex plasticity during the critical developmental period.
• To analyze changes in PKC activity and protein phosphorylation in cat visual cortex across different developmental stages.

Main Methods:

• Assessed cytosolic and membrane PKC activity in cat visual cortex areas 17 and 18.
• Measured endogenous phosphorylation of visual cortical proteins.
• Examined tissue from various postnatal ages, including critical period and adult stages.

Main Results:

• Cytosolic PKC activity showed a substantial increase (8.4–10.9 fold) during the critical period (weeks 3-13), returning to near-adult levels by week 51.
• Membrane PKC activity increased moderately (1.8–2.1 fold), suggesting increased enzyme synthesis rather than translocation.
• Increased phosphorylation of protein F1, a PKC substrate, was observed during the critical period and sustained into adulthood.

Conclusions:

• PKC activity and F1 protein phosphorylation are dynamically regulated during the visual cortex critical period.
• The sustained PKC substrate activity in adulthood provides a molecular mechanism for plasticity in the adult visual cortex.