Purpose: To explore the role of synapsin-Ia/b in visual cortical plasticity, the dynamic changes in total protein expression (T-) and conventional protein kinase C (cPKC)γ-modulated phosphorylation (P-) levels of synapsin-Ia/b were observed in the developing visual cortex of mice.
Methods: The Western blot analysis was used to determine the levels of T- and P-synapsin-Ia/b at site of Ser9, 549, and 603; the cPKCγ gene wild-type (cPKCγ+/+) and knockout (cPKCγ-/-) mice were applied to explore the modulation of cPKCγ on synapsin-Ia/b phosphorylation status in visual cortex of mice at postnatal 7 to 60 days (P7-P60, n = 6 per group).
Results: The results showed that T-synapsin-Ia/b protein levels significantly increased at P14 to P35 and peaked at P42 to 60 (P < 0.001) in visual cortex when compared with that of P7 cPKCγ+/+ mice, and cPKCγ-/- did not affect this pattern of T-synapsin-Ia/b protein expressions. For synapsin-Ia/b phosphorylation status, the levels of P-Ser9 and 603 synapsin-Ia/b significantly elevated at P21 to P28 (P < 0.05 or 0.001), and then went down and maintained at lower levels at P35 to P60 (P < 0.05 or 0.001) compared with P7 cPKCγ+/+ mice. In addition, the cPKCγ gene knockout could significantly (P < 0.001) inhibit both the increase and decrease of P-Ser9 and 603 synapsin-Ia/b levels when compared with cPKCγ+/+ mice at P7 to P60. However, there were no significant changes of P-Ser549 synapsin-Ia/b in the developing visual cortex of both cPKCγ+/+ and cPKCγ-/- mice at P7 to P60.
Conclusions: These results suggested that both protein expression levels and cPKCγ-modulated phosphorylation status at Ser9 and 603 of synapsin-Ia/b may play important role in developing visual cortex of mice.