Transport of CaM kinase along processes elicited by neuronal contact evokes an inhibition of arborization and outgrowth in D. melanogaster cultured neurons.
Transgenic Drosophila strains expressing an inhibitory peptide of Ca2+/calmodulin dependent protein kinase II (CaM kinase), or a constitutively activated CaM kinase, show altered neuronal process morphology compared to wild type in scanning electron microscopy (SEM) of cultured mature neurons from embryonic neuroblasts. We observed significantly enhanced process growth in cells with inhibited enzyme, and reduced process growth in cells with activated enzyme, suggesting that active CaM kinase is involved in the inhibition of neurite growth during development. The subcellular distribution of CaM kinase in wild type neuronal cultures was determined using a gold particle labeling procedure which allowed the mapping of the enzyme directly in the scanning electron microscope (SEM). Before neuronal contact there was little labeling of processes, but after connections had been made the processes were heavily labeled. Our results suggest that the major transport of CaM kinase to the terminals does not occur until after or during the formation of neuronal connections when a functional synapse might be formed. Taken together, these results suggest a target-dependent transport of the enzyme along processes and an inhibitory role for CaM kinase on neurite branching.
Department of Biology, New York University, New York 10003.
S J
SJ
Broughton
N S
NS
Kane
M
M
Yoder
R J
RJ
Greenspan
A
A
Robichon
D000818:Animals; D001693:Biological Transport, Active; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D015536:Down-Regulation; D004331:Drosophila melanogaster; D005838:Genotype; D008855:Microscopy, Electron, Scanning; D009474:Neurons / Q000166:cytology* / Q000201:enzymology; D013347:Subcellular Fractions / Q000201:enzymology; D015854:Up-Regulation
D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases