Two types of murine CD34 mRNA generated by alternative splicing
J Suda, T Sudo, M Ito, N Ohno, Y Yamaguchi and T Suda
Biomaterial Research Institute Co Ltd, Yokohama, Japan.
To characterize and clarify the function of CD34 antigen experimentally, we
isolated two types of CD34 mRNA from a cDNA library of murine stromal cell
line, PA-6 stimulated with lipopolysaccharide (LPS) and
12-o-tetra-decanoylphorbol 13-acetate (TPA) using a human CD34 probe. In
addition to the clone (open reading frame [ORF]:1149bp) reported by Brown
et al, a novel clone (ORF:978 bp) was obtained. The difference between the
two clones was in the cytoplasmic portion of CD34; the former has 73 amino
acids, while the latter has 16. We investigated the genomic sequence of
cytoplasmic portion and found conserved nucleotide sequences at the
exon-intron junction (GT ... AG). Thus, it was concluded that alternative
splicing gave two types of CD34 mRNA. A novel clone contains the longer
cDNA, including a insert of 156 bp, but results in a shorter predicted
coding sequence because of the introduction of an inframe stop codon.
Northern blot analysis using a murine cDNA probe (HindIII fragment, 900 bp)
showed that CD34 was highly expressed in the brain and testis, and
moderately in the thymus, spleen, and bone marrow, but not in adult liver.
However, day 12 to 14 fetal liver cells showed significant expression of
CD34. Quantitative reverse transcription polymerase chain reaction showed
that spleen, thymus, bone marrow, and testis RNA gave two bands of almost
equal intensity, but in the brain a novel clone was expressed three times
more than the other clone. Furthermore, Northern blot analysis using a
probe (156 bp) specific for the spliced intracellular region confirmed the
significant mRNA expression of a novel clone. Although the biologic
significance of alternative splicing remains to be elucidated, it is
suggested that a different carboxyterminal tail causes a change in signal
transduction.
Volume 79,
Issue 9,
pp. 2288-2295,
05/01/1992
Copyright © 1992 by The American Society of Hematology
