Inhibition of Neurite Outgrowth by Overexpression of Goa

Ghil, Sung Ho; Kim, Bum Jun; Lee, Young Don; Suh, Hae Young

Abstract

G proteins mediate signal transductions generated by neurotransmitters and hormones. Among G proteins, Go is found in a large quantity in brain, but its precise role in the nervous tissue is not fully understood. In addition, Go is one of the major proteins in growth cone membranes, which implies an important role of Go in the regulation of axon outgrowth. In this study, we attempted to determine the role of Go in axon outgrowth. We overexpressed the a subunit of Go (ao) in F11 neuroblatoma cells and examined the effect of ao on the neurite outgrowth. In F11 cells, dibutyryl cAMP increased neurite outgrowth remarkably upto 0.1 mM in a concentration dependent manner, but in a less degree at higher concentration. In the presence of 0.5 mM dibutyryl cAMP, the differentiation of F11 cells was almost saturated and the cells exhibited a typical neuronal morphology. Overexpression of ao caused a reduction of neurite outgrowth by 77.4% in length while increasing the number of neurites by 2.2 fold. The average neurite length was 38.9+/-12.5 mm in the ao-overexpressing F11 cells but 172.3+/-25.9 mm in the untransfected cells The total number of nurites per cell was 5.6+/-0.4 in the ao-overexpressing cells but 2.5 0.2 in the untransfected cells. This result suggests that Go may play an important role in growth cone collapse during neuronal cell differentiation.