| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2000: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
We identified aberrant mRNA species in the brain of PrP knockout mice (Prnp-/- Nagasaki), which mRNAs were the novel sequence encoding PrP-like protein (Dopple/PrPLP), a putative membrane glycoprotein with 23 % identity to PrpC in the primary amino acid structure. The expression tissues and cells for this gene were identified, and the following knowledge was acquired.
(1) In adult wild-type mice, Dopple/PrPLP mRNA was physiologically expressed at a high level by testis and heart, bat was barely detectable in brain. However, transient expression of Dopple/PrPLP mRNA was detectable by Northern blotting in the brain of neonatal wild-type mice, showing maximal expression around 1 week after birth. In situ hybridization paired with immunohistochemistry Identified brain endothelial cells as expressing the transcripts. Moreover, in the neonatal wild-type mice, the Dopple/PrPLP mRNA localized in capillaries of spleen and lamina propria mucosa of gut. These findings suggested a role of Dopple/PrPLP in angiogenesis, in particular blood-brain barrier maturation.
(2) In a testis of neonatal mice, the expression of mRNA was found in the leaf cells specializing in the lymph vessel in the future. On the other hand, from the 3rd week after birth, the spermatogonia at the stage IV-VI day of the spermatogenic cycle became to strongly express Dopple/PrPLP mRNA. Hence, Dopple/PrPLP may play an important role in the spermatogenesis and blood-testis barrier.
(3) Northern blotting demonstrated unregulated expression of the genes for GFAP and LM in the brains of PrP knockout mice. A transgene for normal mouse PrP^C- successfully rescued PrP knockout mice from the glial activation. Moreover, the glial cell activation was notable well before the onset of the Purkinje cell degeneration. These findings strongly suggest that ectopic Dopple/PrPLP in the absence of Prp^C is actively involved in the glial-cell activation in the brain.
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