Research article

A chemical-genetic strategy reveals distinct temporal requirements for SAD-1 kinase in neuronal polarization and synapse formation

Joanne SM Kim^1,2 , Brendan N Lilley³ , Chao Zhang⁴ , Kevan M Shokat⁴ , Joshua R Sanes³ and Mei Zhen^1,2

¹  Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada

²  Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada

³  Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA

⁴  Howard Hughes Medical Institute and Department of Molecular and Cellular Pharmacology, University of California, San Francisco, CA 94143, USA

author email corresponding author email

Neural Development 2008, 3:23doi:10.1186/1749-8104-3-23

Published:	22 September 2008

Abstract

Background

Neurons assemble into a functional network through a sequence of developmental processes including neuronal polarization and synapse formation. In Caenorhabditis elegans, the serine/threonine SAD-1 kinase is essential for proper neuronal polarity and synaptic organization. To determine if SAD-1 activity regulates the establishment or maintenance of these neuronal structures, we examined its temporal requirements using a chemical-genetic method that allows for selective and reversible inactivation of its kinase activity in vivo.

Results

We generated a PP1 analog-sensitive variant of SAD-1. Through temporal inhibition of SAD-1 kinase activity we show that its activity is required for the establishment of both neuronal polarity and synaptic organization. However, while SAD-1 activity is needed strictly when neurons are polarizing, the temporal requirement for SAD-1 is less stringent in synaptic organization, which can also be re-established during maintenance.

Conclusion

This study reports the first temporal analysis of a neural kinase activity using the chemical-genetic system. It reveals that neuronal polarity and synaptic organization have distinct temporal requirements for SAD-1.