Developmental changes of CaMKII localization, activity and function during postembryonic CNS remodelling in Manduca sexta

Abstract

Insect metamorphosis is a compelling example of postembryonic remodelling of neuronal structure and synaptic connectivity as larval and adult behaviours place distinct demands on the CNS. Holometabolous insects such as the moth Manduca sexta have long served as suitable models for the study of steroid effects on CNS remodelling, but activity and calcium-dependent mechanisms have been found to act in concert with hormonal signals. This study examines developmental changes in the localization and the activational state of CaMKII during postembryonic Manduca CNS remodelling. Western blotting, CaMKII purification and autophosphorylation with gamma(32)P-ATP indicate that the lepidopteran CNS may contain only one CaMKII isoform. In situ immunohistochemistry reveals developmental changes in the expression patterns of CaMKII in different types of thoracic neurons and in different neuronal compartments. Early pupal life is characterized by an increase in postsynaptic CaMKII localization, which coincides with a developmental increase in CaMKII activation. Both events correlate temporally with motoneuron dendritic filopodia collapse and rapid synaptogenesis, indicating a possible functional role for CaMKII for the postembryonic development of invertebrate motor circuitry. Substrate phosphorylation assays demonstrate that CaMKII activity in the ventral nerve cord reflects changes in calcium influx through voltage-activated channels as occurring in vivo during normal development.

CaMKII is differentially localized in synaptic regions of kenyon cells within the mushroom bodies of the honeybee brain

“…Investigations in M. sexta revealed an increase in postsynaptic CaMKII activation during early pupal stages (Burkert and Duch, 2006). This was shown to be correlated with dendritic filopodia collapse and rapid synaptogenesis, indicating a possible functional role of CaMKII in postembryonic development of neuronal (dendritic) circuitry.…”

“…Several studies have also suggested a role of CaMKII in neuronal plasticity in insects. For example, in the moth Manduca sexta, CaMKII is likely involved in large-scale dendritic remodeling during postembryonic development (Burkert and Duch, 2006). In the honeybee Ca 2þ was…”

Constitutive Activation of Ca2+/Calmodulin-Dependent Protein Kinase II during Development Impairs Central Cholinergic Transmission in a Circuit Underlying Escape Behavior inDrosophila

“…However, we do not favor the latter explanation based on previous work on giant neurons in culture (Yao and Wu, 2001) that respond to CaMKII antagonists, and our own results with the constitutively active CaMKII-T287D suggest that these neurons and relevant synapses of the GFS contain the molecular machinery to respond to the elevated kinase activity. This, along with the abundant neuronal expression of the kinase, suggest that it is normally present in the circuit, although its unequivocal demonstration (Schmitt et al, 2004;Burkert and Duch, 2006) is not trivial and is the subject of ongoing work. Our data indicate that the electrophysiological phenotypes result from sustained CaMKII activity during development of cholinergic synapses.…”

Developmental distribution of CaM kinase II in the antennal lobe of the sphinx moth Manduca sexta

“…The in-vivo treatment of animals with the CaM kinase blocker KN-93 followed the protocol described by Burkert and Duch (2006). The blocker was dissolved in deionized water (5 mM), and 40 μl of this solution was injected into the animal as described by Lohr et al (2005), resulting in a final concentration of KN-93 in the hemolymph of approximately 100 μM.…”

“…CaM kinase II is involved in the maturation and stabilization of dendrites and synapses in the frog optic tectum (Zou and Cline 1996;Wu and Cline 1998). Recently, Burkert and Duch (2006) have described the CaM kinase II dependence of MN5 motoneuron reorganization during metamorphosis of the sphinx moth Manduca sexta. In developing antennal lobe neurons of Manduca, we have found a changing pattern of acetylcholine receptortriggered Ca 2+ oscillations during synaptogenesis (Lohr 2003).…”