Abstract
O-Acetylation and de-O-acetylation of sialic acids have been implicated in the regulation of a variety of biological phenomena, including endogenous lectin recognition, tumor antigenicity, virus binding, and complement activation. Applying a strategy designed to identify genes preferentially expressed in active sites of embryonic hematopoiesis, we isolated a novel cDNA from the pluripotent hematopoietic cell line FDCPmixA4 whose open reading frame contained sequences homologous to peptide fragments of a lysosomal sialic acid O-acetylesterase (Lse) previously purified from rat liver, but with no evident similarity to endoplasmic reticulum-derived acetylesterases. The expressed Lse protein exhibits sialic-acid O-acetylesterase activity that is not attributable to a typical serine esterase active site. lse expression is spatially and temporally restricted during embryogenesis, and its mRNA levels correlate with differences in O-acetylesterase activity described in adult tissues and blood cell types. Using interspecific backcross analysis, we further mapped the lse gene to the central region of mouse chromosome 9. This constitutes the first report on the molecular cloning of a sialic acid-specific O-acetylesterase in vertebrates and suggests novel roles for the 9-O-acetyl modification of sialic acids during the development and differentiation of mammalian organisms.
Highlights
O-Acetylation and de-O-acetylation of sialic acids have been implicated in the regulation of a variety of biological phenomena, including endogenous lectin recognition, tumor antigenicity, virus binding, and complement activation
Applying a strategy designed to identify genes preferentially expressed in active sites of embryonic hematopoiesis, we isolated a novel cDNA from the pluripotent hematopoietic cell line FDCPmixA4 whose open reading frame contained sequences homologous to peptide fragments of a lysosomal sialic acid O-acetylesterase (Lse) previously purified from rat liver, but with no evident similarity to endoplasmic reticulum-derived acetylesterases
Molecular Cloning of a Novel cDNA Encoding Mouse Lse—In a previous report, we described a strategy directed toward the understanding of early hematopoietic development by isolating cDNAs preferentially expressed in the yolk sac, up-regulated during the in vitro development of embryoid bodies (EBs), and expressed in the pluripotent hematopoietic cell line FDCPmixA4 [17]
Summary
Vol 271, No 23, Issue of June 7, pp. 13697–13705, 1996 Printed in U.S.A. Molecular Cloning and Characterization of Lysosomal Sialic Acid O-Acetylesterase*. We further mapped the lse gene to the central region of mouse chromosome 9 This constitutes the first report on the molecular cloning of a sialic acid-specific O-acetylesterase in vertebrates and suggests novel roles for the 9-O-acetyl modification of sialic acids during the development and differentiation of mammalian organisms. One modification of particular interest is the Oacetylation and de-O-acetylation of sialic acids, which determines the presence or absence of the outermost possible structure on typical N-linked oligosaccharides, i.e. O-acetyl esters [6] These esters have been implicated in lectin recognition, cell adhesion, tissue morphogenesis, and a variety of other biological phenomena, including tumor antigenicity, virus binding, and complement activation [1,2,3]. The molecular cloning of lse should allow the study of the role of sialic acid esterases in development and tumorigenesis, a task that until now was impaired by the lack of any vertebrate cDNA encoding these enzymes
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