Phosphorylation of Superior Cervical Ganglion Proteins During Regeneration

Abstract

The incorporation of radioactive phosphate into proteins of both normal and regenerating ganglia of the sympathetic nervous system of the rat is reported. The incorporation reactions were carried out in vitro by incubating homogenates of excised ganglia with [gamma-32P]ATP under various conditions. It was found that incorporation of phosphate into proteins of regenerating ganglia in the molecular mass range 10,000-100,000 daltons increased up to 40% over incorporation into proteins from control ganglia during the first 3 days following injury and returned to control levels after 14 days. Analysis of the proteins by two-dimensional electrophoresis revealed that only few, i.e., less than 20, became radioactively labelled in homogenates of superior cervical ganglia in the presence of Ca2+, and even fewer in the presence of cyclic AMP. Furthermore, all these proteins fell within a narrow pI range of 4-6. The growth-associated protein, variously designated GAP-43, B-50, F-1, and pp46, has an enhanced level of expression and phosphorylation in regenerating ganglia compared with controls at day 3. Injury also caused consistently higher levels of incorporation into two other proteins with molecular masses at positions 55,000 and 85,000 and pI values of 5.1 and 4.5, respectively; the former protein most probably is beta-tubulin. The fact that both proteins are found in the 15,000 g pellet after the tissue has been solubilized in 0.5% nonionic detergent indicates that they may indeed by components of filament assemblies. Thus, the results suggest that protein phosphorylation is a mechanism involved in cytoskeletal function in regenerating nerve.

Okadaic Acid and Cultured Frog Sciatic Nerves: Potent Inhibition of Axonal Regeneration in Spite of Unaffected Schwann Cell Proliferation and Ganglionic Protein Synthesis

“…There are some reports on changes in the pattern of phosphoproteins during regrowth of peripheral nerves (Bignami et al ., 1986 ;Goldstein et al, 1987;Larrivee and Grafstein, 1987a,b ;Watterson et al ., 1989Watterson et al ., , 1990, and cycles of protein phosphorylation/dephosphoryla-B. SVENSSON ET AL.…”

Effects of protein kinase inhibitors on regeneration in vitro of adult frog sciatic sensory axons

“…There are changes in the pattern of phosphoproteins during peripheral nerve regeneration (Bignami et al, 1986;Goldstein et al, 1987;Watterson et al, 1989Watterson et al, , 1990Larrivee and Grafstein, 1987a,b) which suggest that protein phosphorylations are involved in this process. Their importance remains to be elucidated.…”

A Fast Axonally Transported Protein of the Frog Sciatic Sensory Axons Undergoes Similar Qualitative Changes During Regeneration In Vitro and In Vivo

“…In this context it is interesting to note that a phosphoprotein of goldfish optic nerve of similar molecular weight shows a shift in PI during regeneration [protein 24e (Larrivee and Grafstein, 1989)]. Also, in the rat superior cervical ganglion a set of proteins of -30 kDa has been reported to be phosphorylated during regeneration (Watterson et al, 1989(Watterson et al, , 1990.…”