Expression patterns in alternative splicing forms of prosaposin mRNA in the rat facial nerve nucleus after facial nerve transection.
Prosaposin acts as a neurotrophic factor, in addition to its role as the precursor protein for saposins A, B, C, and D, which are activators for specific sphingolipid hydrolases in lysosomes. In rats, the prosaposin gene generates two alternative splicing forms of mRNA: Pro+9 containing a 9-base insertion and Pro+0 without. The expression of these mRNAs changes after brain injury. We examined the expression patterns of the alternative splicing forms of prosaposin mRNA in the rat facial nerve nucleus for 52 days following facial nerve transection. Pro+0 mRNA increased within 3 days of transection, peaked after 5-10 days, and remained significantly elevated for 21 days. In contrast, the expression of Pro+9 mRNA was constant throughout the regenerative period. Prosaposin mRNA expression increased not only in facial motoneurons, but also in microglia during facial nerve regeneration. Our findings indicate that the saposin B domain of prosaposin, which is the domain affected by alternative splicing, plays an important role in both neurons and microglia during neuroregeneration.
Chen
Jie
J
Division of Anatomy and Embryology, Department of Integrated Basic Medical Science, Ehime University School of Medicine, Shitsukawa, To-on, Ehime 791-0295, Japan.
Saito
Shouichiro
S
Kobayashi
Naoto
N
Sato
Kohji
K
Terashita
Takehiro
T
Shimokawa
Tetsuya
T
Mominoki
Katsumi
K
Miyawaki
Kyojy
K
Sano
Akira
A
Matsuda
Seiji
S
D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D003714:Denervation; D005154:Facial Nerve / Q000378:metabolism* / Q000503:physiopathology; D020220:Facial Nerve Injuries / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D005786:Gene Expression Regulation / Q000502:physiology; D008297:Male; D017628:Microglia / Q000378:metabolism; D009046:Motor Neurons / Q000378:metabolism*; D009416:Nerve Regeneration / Q000235:genetics; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020127:Recovery of Function / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012249:Rhombencephalon / Q000378:metabolism* / Q000503:physiopathology; D049231:Saposins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D015854:Up-Regulation / Q000235:genetics
D020033:Protein Isoforms; C483347:Psap protein, rat; D012333:RNA, Messenger; D049231:Saposins