title: Characterization and partial purification of CD34+ progenitor cell ecto-phosphatidic acid phosphohydrolase.
abstract: Phosphatidic acid and its hydrolysis product, diacylglycerol, play potentially vital roles as extracellular messengers in numerous cellular systems and may play a key role in regulating hematopoiesis. In this study, we describe an ecto-phosphatidic acid phosphohydrolase that potentially regulates cellular responses to phosphatidic acid on bone marrow derived human hematopoietic progenitors. We partially purified hematopoietic progenitor ecto-PAPase using a novel in-gel phosphatase assay and then characterized the enzyme on phenotypically defined subpopulations of hematopoietic CD34+ progenitors isolated by flow cytometry. The most pronounced PAPase activity was confined to uncommitted CD34+/CD38+ hematopoietic progenitors, which lacked the expression of other lineage-associated antigens. We conclude that hematopoietic progenitor cells at various stages of maturation possess a potent ecto-PAPase, an enzyme well positioned to regulate progenitor cell growth and differentiation induced by phosphatidic acid and related lipids.
authors: Experimental Cell Research Laboratory, Methodist Research Institute, Indianapolis, IN, USA.
authors: K A
authors: KA
authors: Harvey
authors: R A
authors: RA
authors: Siddiqui
authors: M
authors: M
authors: Reeves
authors: T
authors: T
authors: Kovala
authors: M
authors: M
authors: Dugan
authors: L P
authors: LP
authors: Akard
authors: D
authors: D
authors: English
mesh_terms: D018952:Antigens, CD34 / Q000378:metabolism*; D005033:Ethylmaleimide / Q000378:metabolism; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000201:enzymology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008954:Models, Biological; D010711:Phosphatidate Phosphatase / Q000737:chemistry* / Q000302:isolation & purification*; D011433:Propranolol / Q000378:metabolism; D012969:Sodium Fluoride / Q000378:metabolism; D013110:Sphingosine / Q000378:metabolism; D013997:Time Factors; D014638:Vanadates / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D014638:Vanadates; D012969:Sodium Fluoride; D011433:Propranolol; D010711:Phosphatidate Phosphatase; D008274:Magnesium; D013110:Sphingosine; D005033:Ethylmaleimide