Enhanced expression of 14-3-3 family members in injured motoneurons.
An increase in 14-3-3 mRNA expression after hypoglossal nerve injury was demonstrated by RNA finger printing using the arbitrary primed polymerase chain reaction (RAP-PCR). RAP-PCR was carried out to compare differences in mRNA expression between axotomized (6 h after the transection) and normal hypoglossal nuclei in mice. The expression of several gene fragments was increased after nerve injury; one fragment was identified as 14-3-3 which is an activator of Raf-1. Since a family of 14-3-3 genes are identified in the rat, we examined the expression of five members of the rat 14-3-3 family after injury (beta, gamma, zeta, eta and theta). Among these family members, a substantial up-regulation in mRNA expression was observed for the zeta and &theta; forms. Subsequent emulsion autoradiography of hybridization tissue sections revealed an increase in zeta and theta mRNA in injured motoneurons. Since 14-3-3 has the ability to dimerize and activate Raf-1, the up-regulation of 14-3-3 expression would be expected to facilitate the Ras-Erk signal pathway by Raf-1 activation. Our previous results have demonstrated that Shc, Erk1 and Mek1 mRNAs are up-regulated during nerve regeneration, whereas PKA which inhibits the Ras-Erk pathway via Raf-1 was down-regulated. Taken together, the present results suggest that enhancement in expression of molecules involved in the Ras-Erk signaling is required for peripheral nerve regeneration.
Namikawa
K
K
Department of Anatomy, Asahikawa Medical College, Nishikagura 4-5-3-11, Asahikawa 078-8510, Japan.
Su
Q
Q
Kiryu-Seo
S
S
Kiyama
H
H
D048948:14-3-3 Proteins; D000818:Animals; D019771:Axotomy; D007002:Hypoglossal Nerve / Q000502:physiology; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009046:Motor Neurons / Q000378:metabolism*; D005810:Multigene Family; D020401:Primed In Situ Labeling; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D017422:Sequence Analysis, DNA; D014446:Tyrosine 3-Monooxygenase
D048948:14-3-3 Proteins; D011506:Proteins; D012333:RNA, Messenger; D014446:Tyrosine 3-Monooxygenase