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First published online November 5, 2008
doi: 10.1242/10.1242/jcs.037507
Commentary |
1 Trev and Joyce Deeley Research Centre, British Columbia Cancer Agency, 2410 Lee Avenue, Victoria, BC, Canada V8R 6V5
2 The Biomedical Research Centre, 2222 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
* Author for correspondence (e-mail: Kelly{at}brc.ubc.ca)
Accepted 30 September 2008
For almost 30 years, the cell-surface protein CD34 has been widely used as a marker to assist in the identification and isolation of hematopoietic stem cells (HSCs) and progenitors in preparation for bone-marrow transplantation. In addition, it has increasingly been used as a marker to help identify other tissue-specific stem cells, including muscle satellite cells and epidermal precursors. Despite its utility as a stem-cell marker, however, the function of CD34 has remained remarkably elusive. This is probably because: (1) it is subject to a range of tissue-specific post-transcriptional and post-translational modifications that are expected to alter its function dramatically; (2) the simple interpretation of CD34 gain- and loss-of-function experiments has been confounded by the overlapping expression of the two recently discovered CD34-related proteins podocalyxin and endoglycan; and (3) there has been a glaring lack of robust in vitro and in vivo functional assays that permit the structural and functional analysis of CD34 and its relatives. Here, we provide a brief review of the domain structure, genomic organization, and tissue distribution of the CD34 family. We also describe recent insights from gain- and loss-of-function experiments and improved assays, which are elucidating a fascinating role for these molecules in cell morphogenesis and migration.
Key words: Podocalyxin, CD34, Endoglycan
