A new Drosophila Ca2+/calmodulin-dependent protein kinase (Caki) is localized in the central nervous system and implicated in walking speed.

Abstract

Calcium/calmodulin‐dependent protein kinases (CaM kinases) have been reported to be involved in neuroplasticity. We have cloned a new Drosophila CaM kinase gene named caki. We describe the molecular characterization of caki and a behavioral effect of its elimination. The caki gene is extremely large; comparison of the genomic and cDNA sequences reveals that the caki transcription unit is at least 150 kb. The catalytic domain of this new CaM kinase protein shares homology (41%) with type II CaM kinases, while the C‐terminal part is divergent. Constitutively expressed Caki protein is enzymatically active since it causes a 3‐fold increase in the level of the Rous sarcoma virus long terminal repeat (RSV LTR) promoter in a co‐transfusion assay. In situ hybridization shows that during embryogenesis, larval and pupal life, transcription of caki is restricted almost exclusively to the central nervous system. In the adult head, immunohistochemistry reveals Caki protein in the lamina, the neuropil of the medulla, lobula, lobula plate and in the central brain. Mutant caki flies show reduced walking speed in ‘Buridan's paradigm’.

Central Regulation of Locomotor Behavior of Drosophila melanogaster Depends on a CASK Isoform Containing CaMK-Like and L27 Domains

“…This line contains a P{EPgy2} insertion in the first intron of the CASK gene at cytological position 3R(93F12) (Spradling et al 1999;Bellen et al 2004). The CASK deficiency lines Df(3R)x307 and Df(3R)x313 (Martin and Ollo 1996) were maintained over TM6Tb-UbGFP and crossed together to generate the transheterozygote null fly 307/313 (as verified by absence of markers and GFP). Df(3R)exel6187 (Parks et al 2004) was maintained over TM6bTb and verified by the absence of the humoral marker.…”

“…One such phenotype is a defect in synaptic plasticity; flies lacking CASK were defective in courtship habituation, which is thought to be mediated via interaction with CaMKII (Lu et al 2003). Loss of CASK also produces a gross locomotor deficit (Martin and Ollo 1996;Sun et al 2009), but the cellular circuitry affected by loss of CASK has not yet been identified. Flies missing the CASK gene also show abnormally long responses to stimulation of the giant fiber pathway, the multisynaptic behavioral circuit that underlies the adult escape response (Zordan et al 2005).…”

“…The reason for this lies in the nature of the CASK null model used in these studies: CASK null flies were produced by crossing together two overlapping deletions [Df(3R)x307 and Df(3R)x313] (Martin and Ollo 1996). The resulting trans-heterozygote flies are unhealthy, infertile, and contain additional heterozygous gene disruptions due either to extension of the deletion into neighboring genes (Martin and Ollo 1996) or to linked lethals outside the CASK region (Dimitratos 1999). An additional complication is that these overlapping deficiencies would be predicted to eliminate both the CASK-b and CASK-a isoforms, making it impossible to assign function to a specific form of the protein.…”

Deletion of CASK in mice is lethal and impairs synaptic function

“…A large number of MAGUKs with these domains were described, but CASK is the only MAGUK that contains an additional large N-terminal domain with homology to calcium/ calmodulin-dependent protein kinase II␣ (3). CASK was independently discovered in vertebrates because it binds to neurexins, cell-adhesion molecules with a possible function in synapse formation (3), in Drosophila (where it is called CamGUK) because its mutation causes a behavioral phenotype (4), and in Caenorhabditis elegans (where it is called lin-2) because its mutation induces abnormal vulva development (5).…”

Development of the Cellular Immune System of Drosophila Requires the Membrane Attack Complex/Perforin-Like Protein Torso-Like

“…A significant decrease in phagocytosis was observed in tsl mutant females compared to tsl D /+ heterozygous controls after infection with either E. coli (unpaired t-test, P , 0.001) or S. aureus (P = 0.038) pHrodo bacterial particles (Figure 3). To confirm that this defect was due to loss of tsl, we also measured phagocytic ability in female flies trans-heterozygous for tsl D and a deficiency line that removes tsl, Df caki (Martin and Ollo 1996;Grillo et al 2012). The tsl D /Df caki flies also phagocytosed significantly fewer E. coli and S. aureus than the controls (P , 0.001; Figure 3).…”