A common signaling pathway via Syk and Lyn tyrosine kinases generated fromcapping of the sialomucins CD34 and CD43 in immature hematopoietic cells

Citation
J. Tada et al., A common signaling pathway via Syk and Lyn tyrosine kinases generated fromcapping of the sialomucins CD34 and CD43 in immature hematopoietic cells, BLOOD, 93(11), 1999, pp. 3723-3735
Citations number
55
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Hematology,"Cardiovascular & Hematology Research
Journal title
BLOOD
ISSN journal
0006-4971 → ACNP
Volume
93
Issue
11
Year of publication
1999
Pages
3723 - 3735
Database
ISI
SICI code
0006-4971(19990601)93:11<3723:ACSPVS>2.0.ZU;2-1
Abstract
The sialomucin CD34 is a useful marker for hematopoietic stem/progenitor ce lls, However, the role of CD34 remains poorly understood. Here we investiga te the functions of CD34 and another sialomucin CD43 coexpressed on hematop oietic stem/progenitor cells. Stimulation of undifferentiated hematopoietic KG1a cells with anti-CD34 or anti-CD43 induced homotypic cytoadhesion, acc ompanied by formation of a long-lived cap of CD34 and CD43 respectively, wh ich colocalized with F-actin. Stimulation with either antibody specifically increased tyrosine phosphorylation of the identical set of proteins of Lyn , Syk, pp60, pp69, and pp77 at the capping site. These events were similar to those observed in monocytic U937 cells ectopically expressing CD34. Afte r stimulation of KG1a cells, coimmunoprecipitation of Lyn with pp69 and pp7 7 and of Syk with pp37 was detected in the membrane fraction, Blockade of a ntibody-induced cap formation by treatment with cytochalasin D leads to inh ibition of tyrosine phosphorylation of Syk and pp77 and homotypic cytoadhes ion. Moreover, normal human CD34(+) bone marrow cells showed cap formation of CD34 or CD43 after stimulation. These results suggest that crosslinking of either CD34 or CD43 activates the same signaling pathway for cytoadhesio n through Lyn, Syk, and the novel tyrosine-phosphorylated proteins within h ematopoiesis. (C) 1999 by The American Society of Hematology.