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Comment |
Takahashi A, et al reported that a splicing factor, Prp8: Preferential localization in the
testis and ovary in adult mice.
Prp8 is a splicing factor of 220 kDa originally identified in yeast and is a
component of the U5 small nuclear ribonucleoprotein particle. Mouse PrpS cDNA
was cloned and shown to share 62.6 and 68.2% sequence identity with the yeast
homologue at the amino acid and nucleotide level, respectively, while it
differs by only 3 amino acid residues from the human homologue, During mouse
embryogenesis, Prp8 is expressed intensely at day 9.5 of gestation, and its
expression decreases progressively during embryogenesis. In adult mice, Prp8
is expressed strongly in the testis and moderately in the ovary. In situ
hybridization analysis revealed that Prp8 is preferentially expressed in the
outer cell layer in the testis, probably in the spermatogonia and primary
spermatocytes, and in granulosa cells in the ovary. In Caenorhabditis elegans,
microinjection of a double stranded RNA corresponding to a portion of the Prp8
sequence results in the arrest of embryogenesis at the late-gastrulation
stage. These results suggest that Prp8 plays an important role in reproduction
and development. Prp8 was shown to bind to midkine (MK), a heparin-binding
growth factor. Since Prp8 expression partially overlaps with the sites of
action of MK, it is possible that binding to PrpS is involved in part of MK
signaling.
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