Distinct developmental expression of two isoforms of Ca²⁺/calmodulin-dependent protein kinase kinases and their involvement in hippocampal dendritic formation

Ca²⁺/calmodulin-dependent protein kinase kinases (CaMKKs) are upstream protein kinases that phosphorylate and activate CaMKI and CaMKIV, both of which are involved in a variety of neuronal functions. Here, we first demonstrated that the two isoforms of CaMKK were differentially expressed during neural development by in situ hybridization. We also demonstrated that both dominant negative and pharmacological interference with CaMKK inhibitor, STO-609 resulted in a significant decrease in the number of primary dendrites of cultured hippocampal neurons. Our present findings provide the detailed anatomical information on the developmental expression of CaMKKs and the functional involvement of CaMKK in the formation of primary dendrites.