Calcium/calmodulin-dependent protein kinase IIβ isoform is expressed in motor neurons during axon outgrowth and is part of slow axonal transport

• Published in: Journal of neuroscience research Vol. 67; no. 6; pp. 720 - 728
• Main Authors: Lund, Linda M., McQuarrie, Irvine G.
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 15-03-2002
• Subjects: axonal transport; axotomy; CaMKIIβ; CNS; sciatic motor neurons
• ISSN: 0360-4012; 1097-4547
• DOI: 10.1002/jnr.10162

Previously, we identified calcium/calmodulin‐dependent protein kinase IIβ (CaMKIIβ) mRNA in spinal motor neurons with 372 bp inserted in what corresponds to the “association” domain of the protein. This was interesting because known additions and deletions to CaMKIIβ mRNA are usually less than 100 bp in size and found in the “variable” region. Changes in the association domain of CaMKIIβ could influence substrate specificity, activity or intracellular targeting. We show that three variations of this insert are found in CNS neurons or sciatic motor neurons of Sprague–Dawley rats. We used PCR and nucleic acid sequencing to identify inserts of 114, 243, or 372 bases. We also show that addition of the 372 bases is associated with outgrowth of the axon (the standard CaMKIIβ downregulates when axon outgrowth occurs). Radiolabeling, immunoblots, and 2D PAGE identified this larger CaMKIIβ as part of the group of soluble proteins moving at the slowest rate of axonal transport (SCa) in sciatic motor neurons (∼1 mm/day). This group is composed mainly of structural proteins (e.g., tubulin) used to assemble the cytoskeleton of regrowing axons. Published 2002 Wiley‐Liss, Inc.