Axonal Transport of the Molecular Forms of Acetylcholinesterase in Chick Sciatic Nerve

Abstract

Acetylcholinesterase (AChE) polymorphism was studied in the sciatic nerve of 4-week-old Leghorn chicks, by sucrose gradient sedimentation analysis. Four main AChE molecular forms were found with sedimentation coefficients of 5S, 7.5S, 11.5S and 20S respectively. Axonal transport of each of these forms was investigated on the basis of the enzyme accumulation kinetics measured on both sides of nerve transections and of the enzyme redistribution kinetics in nerve segments isolated in vivo. After nerve transection, 11.5S and 20S forms accumulated faster in the anterograde than in the retrograde direction and also much faster than 5S and 7.5S forms in the anterograde direction. Retrograde accumulations of 5S and 7.5S were faint or negligible. In addition, 1 h after nerve cutting, the accumulation rates for 11.5S and 20S forms (but not for 5S and 7.5S) fell, in both directions, to about one-third of their initial values, probably owing to reversal of axonal transport at the axotomy site. Local protein synthesis inhibition by cycloheximide did not affect the accumulation of 11.5S and 20S in front of a transection, at least during the first hours, but reduced that of 5S and 7.5S by about 40%. In isolated nerve segments in vivo, the rapidly mobile fraction of AChE was estimated to constitute 23% of the total enzyme activity present in the nerve, 14% of it moving in an anterograde and 9% in a retrograde direction. A small amount of 11.5S molecules (approx. 20%) was in rapid transit (two-thirds in the anterograde and one-third in the retrograde direction), whereas almost all the 20S--about 90%--migrated rapidly (two-thirds forwards and one-third backwards). Anterograde velocities of 408 +/- 94 and 411 +/- 161 mm/day respectively were estimated for the 11.5S and 20S forms. Their respective retrograde velocities were 175 +/- 85 and 145 +/- 107 mm/day. Assuming that the totality of 5S and 7.5S molecules are moving in the anterograde direction, their accumulation rates were consistent with the average anterograde velocities of 2.9 +/- 1.3 and 5.1 +/- 1.4 mm/day, respectively.

Restricted localization of proline‐rich membrane anchor (PRiMA) of globular form acetylcholinesterase at the neuromuscular junctions – contribution and expression from motor neurons

“…The level of AChE increased during development, and was reduced after section of the sciatic nerve. The current results are in line with our previous observation that chick motor neurons contain collagen-tailed AChE as well as globular forms [15,19,20]. In contrast, frog motor axons have been shown to produce collagentailed AChE, which could be deposited in the synaptic basal lamina at NMJs [14].…”

The Anterograde Transport of Rabies Virus in Rat Sensory Dorsal Root Ganglia Neurons

“…We presume that the virus is transported across the nerve cell without replicating in the cell soma. Similar fast anterograde transport mechanisms have been widely reported for other cellular components (Couraud & DiGiamberardino, 1980;Gilbert et al, 1985;Lorenz & Willard, 1978;Lubinska & Niemierko, 1971 ;Ochs, 1972). The mean velocity of rabies virus fast transport was estimated to be in the range of 100 to 400 mm per day which is in accordance with the velocities (360 mm/day) reported for rat sensory neurons (Aquino et al, 1987).…”

“…Indeed different modes and velocities of transport have been described (Lorenz & Willard, 1978;Tytell et al, 1981). For example, different molecular forms of acetylcholinesterase are transported at various velocities ranging from 3 to 400 mm/day (Couraud & DiGiamberardino, 1980). It is tempting to assume that the transport of rabies virus by neurons follows a pattern similar to that of other biological molecules such as lectins, tetanus toxin and nerve growth factor which are receptor-mediated (Stockel et al, 1975) and transported by vesicular organelles (Schwab, 1977).…”

A Globular, Not Asymmetric, Form of Acetylcholinesterase Is Expressed in Chick Motor Neurons: Down‐Regulation Toward Maturity and After Denervation

“…Indeed, the capability of a motor neuron that can express asymmetric AChE in an intact frog neuromuscular junction is still not known. The AChE synthesized in the motor neuron is axonally transported to the presynaptic terminal as demonstrated by enzymatic and microscopic studies (Couraud and Di Giamberardino, 1980;Goemaere-Vanneste et al, 1988). Some of these enzymes may never reach nerve ending and may either be released into the extracellular spaces (Kreutzberg et al, 1973;Oh et al, 1977) or be attached to the axolemma at sites along the axon (Brimijoin et al, 1978;Li and Bon, 1983).…”