RETROGRADE AXONAL-TRANSPORT OF THE ALPHA-SUBUNIT OF THE GTP-BINDING PROTEIN G(Z) IN MOUSE SCIATIC-NERVE - A POTENTIAL PATHWAY FOR SIGNAL-TRANSDUCTION IN NEURONS

We have utilized antibodies against the a subunit of G(z) in fluoresce nce immunohistochemistry to determine whether this GTP-binding protein can translocate along nerves by intra-axonal transport. After ligatio n of the mouse sciatic nerve we found an increase in G(z)-like immunor eactivity on the proximal and distal side with time, suggesting that t he alpha subunit undergoes orthograde axonal transport and also return s to the cell body by retrograde axonal transport in the sciatic nerve . Unlike the retrograde transport of G(i alpha), shown in a previous s tudy to be present in most sciatic axons, G(z alpha) only accumulated in a subpopulation of axons, suggesting that different G-proteins coul d convey information specific to neuronal subtypes. These results supp ort our proposal that G(z) may play a second messenger role in communi cating information from the terminals back to cell bodies. G(i alpha) and G(z alpha) may be representative of relatively stable signalling m olecules by which the signal from some neurotrophic molecules can be t ranslocated from the neuronal periphery to the cell body without the n eed for the retrograde transport of the neurotrophic factor itself.