Differential regulation of phospholipase C isozymes in the rat facial nucleus following axotomy.
The expression of phospholipase C isozymes and phosphatidylinositol 4-kinase in the rat facial nucleus was studied using in situ hybridization at various times after unilateral crushing and resectioning the facial nerve. The level of phospholipase C alpha messenger RNA increased from three days to one week after the operation. On the other hand, an apparent reduction in the level of phospholipase C beta 1 occurred from three days to one week after resection. After either crushing or resection, phospholipase C gamma 1 messenger RNA levels were not noticeably changed. As phosphatidylinositol 4-kinase is the rate-limiting enzyme for the production of phosphatidylinositol 4,5-bisphosphate, which is the preferred substrate for phospholipase C, we investigated the expression of phosphatidylinositol 4-kinase messenger RNA. The level of phosphatidylinositol 4-kinase messenger RNA was decreased one day after axonal injury. Among phospholipase C isozymes, phospholipase C alpha is up-regulated. As the structure of phospholipase C alpha is different from other isozymes, phospholipase C alpha is supposed to have a different function. The present unique up-regulation of phospholipase C alpha may suggest a novel function in nerve regeneration. Phospholipase C beta 1 is down-regulated, as is phosphatidylinositol 4-kinase. This suggests that the signal transmission system using a G-linked receptor is broken down after nerve injury. On the other hand, phospholipase C gamma 1, which is related to the receptor tyrosine kinase, does not demonstrate any transcriptional regulation after nerve injury.
Saika
T
T
Department of Otolaryngology, Osaka University Medical School, Japan.
Kiyama
H
H
Matsunaga
T
T
Tohyama
M
M
D019870:1-Phosphatidylinositol 4-Kinase; D000818:Animals; D001369:Axons / Q000502:physiology*; D001921:Brain / Q000166:cytology / Q000502:physiology*; D003714:Denervation; D005154:Facial Nerve / Q000502:physiology*; D017403:In Situ Hybridization; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009046:Motor Neurons / Q000378:metabolism; D009409:Nerve Crush; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism*
D007527:Isoenzymes; D012333:RNA, Messenger; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase; D010738:Type C Phospholipases