Netrin-1 Peptide Is a Chemorepellent in Tetrahymena thermophila

Table 2

Pharmacological studies suggest that a tyrosine kinase is involved in the avoidance of netrin-1 peptide in Tetrahymena. Inhibition of G-proteins, chelation of intracellular and extracellular calcium, and inhibition of a number of other kinases had no effect on avoidance behavior. The tyrosine kinase inhibitor, genistein, reduced avoidance to baseline levels. “Avoidance” represents the mean ± standard deviation of 6 trials. Each trial consisted of 10 cells which were individually observed and scored for avoidance within the first 5 seconds of exposure to netrin-1 peptide.

Pharmacological agent	Mechanism of action	Concentration tested	Avoidance
EGTA	Chelates extracellular calcium	100 μM	100 ± 0%
BAPTA-AM	Chelates intracellular calcium	100 μM	96.6 ± 5.8%
Thapsigargin	Depletes ER calcium stores	100 μM	100 ± 0%
GDP--S	Inhibits G-proteins	1 mM	93.3 ± 5.8%
Pertussis toxin	Inhibits Gi/o proteins	0.2 μg/mL	96.6 ± 5.8%
Rp-cAMPs	Inhibits protein kinase A	100 μM	93.3 ± 5.8%
U73122	Inhibits phospholipase C	1 μM	95.0 ± 5.0%
Genistein	Inhibits tyrosine kinases	100 μg/mL	16.7 ± 4.5%
Daidzein	Negative control for genistein	100 μg/mL	98.3 ± 4.1%
Neomycin sulfate	Competitive inhibitor for lysozyme/PACAP receptor	100 μM	93.3 ± 5.8%
SU6668	Protein kinase Inhibitor	100 μM	100 ± 0%
NS2028	Guanylyl cyclase inhibitor	100 μM	100 ± 0%
GSK429286	Rho kinase inhibitor	100 μM	100 ± 0%
Src inhibitor 1	Inhibits Src family kinases	100 μM	100 ± 0%
FAK inhibitor 14	Inhibits focal adhesion kinase	100 μM	93.3 ± 5.8%
Sodium orthovanadate	Inhibits tyrosine phosphatases	100 μM	97.5 ± 5.0%