The goal of the proposed research is to investigate neuron and muscle excitability in the nematode C. elegans. We have identified over 30 genes that regulate excitation of defecation, egg-laying, and body-wall muscles, and we have molecularly cloned five of these genes. The genetics of four of these is strikingly similar: each has dominant gain-of-function mutations (gf) that cause strong defects in muscle excitation, and loss-of-function (lf) mutations cause little or no obvious phenotype. All four genes encode K+ channels. We think that the gf mutations in each K+ channel cause channel activation in vivo, accounting for their strong excitation defects. The fact that lf mutations cause relatively minor defects suggests that the many K+ channels have overlapping functions in vivo. We will continue analysis of these genes and other similar genes identified in genetic screens. The K+ channels will be expressed in cultured cells to study their electrophysiological properties. It will be particularly interesting to study how the gf mutations affect channel properties. Two of these K+ channels are related to the human HERG channel, defects in which cause a cardiac malfunction called long-QT. Long-QT can also be caused by tricyclic antidepressants and certain cardiac anti-arrhythmic drugs. We have evidence that these drugs also block one (but not the other) of the C. elegans HERG-related channels in vivo and in vitro. We will study the C. elegans channels and their human equivalents to understand the basis for this specificity and its implications for long-QT disorder. We have shown that the fifth muscle excitation gene, called unc- 43, encodes the nematode homologue of calcium-calmodulin dependent protein kinase II (CaMKII). CaMKII is implicated as a key regulator of synaptic activity, particularly of synaptic plasticity that underlies learning and memory. We have many lf mutations in unc-43, including null mutations. These mutants are viable and have complex behavioral abnormalities. There is also one gf mutation in unc-43, and we think that this mutant CaMKII is partially Ca++ independent (activated). This gf mutant is also viable and confers complex defects that are the opposite of those in null mutants. We have begun to use the unc-43 activated mutation to identify extragenic suppressors of its various phenotypes, some of which we expect to encode direct CaMKII substrates. We propose to use a combination of genetic analysis, molecular cloning, and biochemical analysis to characterize these potential targets and to determine whether they are directly phosphorylated by the unc-43 CaMKII. We will also continue genetic screens to identify additional potential targets.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS030187-10
Application #
6351816
Study Section
Special Emphasis Panel (ZRG1-MDCN-3 (01))
Program Officer
Edwards, Emmeline
Project Start
1992-01-01
Project End
2003-01-31
Budget Start
2001-02-01
Budget End
2002-01-31
Support Year
10
Fiscal Year
2001
Total Cost
$326,816
Indirect Cost
Name
University of Washington
Department
Genetics
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
Reiner, David J; Weinshenker, David; Tian, Hong et al. (2006) Behavioral genetics of caenorhabditis elegans unc-103-encoded erg-like K(+) channel. J Neurogenet 20:41-66
Robatzek, M; Niacaris, T; Steger, K et al. (2001) eat-11 encodes GPB-2, a Gbeta(5) ortholog that interacts with G(o)alpha and G(q)alpha to regulate C. elegans behavior. Curr Biol 11:288-93
Chamberlin, H M; Thomas, J H (2000) The bromodomain protein LIN-49 and trithorax-related protein LIN-59 affect development and gene expression in Caenorhabditis elegans. Development 127:713-23
Chamberlin, H M; Brown, K B; Sternberg, P W et al. (1999) Characterization of seven genes affecting Caenorhabditis elegans hindgut development. Genetics 153:731-42
Weinshenker, D; Wei, A; Salkoff, L et al. (1999) Block of an ether-a-go-go-like K(+) channel by imipramine rescues egl-2 excitation defects in Caenorhabditis elegans. J Neurosci 19:9831-40
Iwasaki, K; Staunton, J; Saifee, O et al. (1997) aex-3 encodes a novel regulator of presynaptic activity in C. elegans. Neuron 18:613-22
Johnstone, D B; Wei, A; Butler, A et al. (1997) Behavioral defects in C. elegans egl-36 mutants result from potassium channels shifted in voltage-dependence of activation. Neuron 19:151-64
Chamberlin, H M; Palmer, R E; Newman, A P et al. (1997) The PAX gene egl-38 mediates developmental patterning in Caenorhabditis elegans. Development 124:3919-28
Reiner, D J; Weinshenker, D; Thomas, J H (1995) Analysis of dominant mutations affecting muscle excitation in Caenorhabditis elegans. Genetics 141:961-76
Weinshenker, D; Garriga, G; Thomas, J H (1995) Genetic and pharmacological analysis of neurotransmitters controlling egg laying in C. elegans. J Neurosci 15:6975-85

Showing the most recent 10 out of 12 publications