Journal of Dental Research, Vol 74, 319-322, Copyright © 1995 by International & American Associations for Dental Research Online Journals
Identification of bone-type alkaline phosphatase mRNA from human periodontal ligament cells
M. Goseki, S. Oida, K. Takeda, Y. Ogata, T. Iimura, Y. Maruoka and S. Sasaki
Department of Biochemistry, School of Dentistry, Tokyo Medical and Dental University, Japan.
Tissue-nonspecific-type alkaline phosphatase is found in the bone, liver,
kidney, and other tissues, and its gene consists of 12 exons with the
coding sequence beginning in the second exon. Recently, an alternative
noncoding first exon was identified in the liver message which differed
from that of the previously known osteoblast-derived cDNA sequence.
Although these two mRNAs produce an identical protein, they have different
promoter regions. The periodontal ligament tissue expresses a high level of
alkaline phosphatase activity. To identify its mRNA type, we isolated a
full-length cDNA for alkaline phosphatase from a cultured human periodontal
ligament cell expression library, using bone-derived tissue-nonspecific
alkaline phosphatase cDNA as a hybridization probe. The size of this clone
was 2.5 kb, and its 5' and 3' untranslated sequences were identical to
those of the human tissue-nonspecific type isolated from osteoblastic cells
but not to those of the liver type. In addition, the same fragments as in
bone-derived tissue-nonspecific-type cDNA were detected by the treatment of
the cDNA clone with restriction enzymes Hinc II and Pst I. The results
suggest that expression of the same alkaline phosphatase isozyme in human
periodontal ligament cells may be regulated by the same transcriptional
mechanism as in bone.
