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Blood, 15 March 2007, Vol. 109, No. 6, pp. 2373-2379. Prepublished online as a Blood First Edition Paper on November 9, 2006; DOI 10.1182/blood-2006-05-026039. This Article Full Text (PDF) All Versions of this Article: blood-2006-05-026039v1 109/6/2373    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Dao, M. A Articles by Nolta, J. A. Search for Related Content PubMed PubMed Citation Articles by Dao, M. A Articles by Nolta, J. A. Social Bookmarking                   What's this?  Previous Article  |  Next Article  Submitted May 30, 2006 Accepted October 27, 2006 Cytokine and integrin stimulation synergize to promote higher levels of GATA-2, c-myb, and CD34 protein in primary human hematopoietic progenitors from bone marrow Mo A Dao and Jan A. Nolta* Div. of Oncology, Hematopoietic Develop. & Malignancy Progam, Washington University School of Medicine, St. Louis, MO * Corresponding author; email: jnolta{at}im.wustl.edu. We have previously shown that engagement of the integrins VLA-4 and VLA-5 to the fibronectin fragment CH-296 in combination with cytokines sustained the capacity of cultured human CD34+ cells to undergo hematopoiesis in immune deficient mice for 7 to 12 months, whereas this capacity was rapidly lost in cells cultured in suspension with the same cytokines. In the current study, we assessed the molecular pathways which might explain the loss of long term engraftment capacity in cells cultured in suspension. Although the cell cycle profile was similar between cells cultured in suspension vs. on fibronectin, levels of cell death were higher in the suspended cultures. While the CDK inhibitors p27Kip1 and p57Kip2 were present at equal levels in cells from both cultures, low levels of p21Cip1 were detectable only in the cytoplasmic compartment of cells cultured in suspension. Cytoplasmic location of p21Cip1 has been linked to monocytic differentiation. The levels of c-myb and GATA-2, transcription factors associated with stem cell maintenance, were higher in cells cultured on fibronectin, as compared to suspension. In contrast, the levels of PU.1, which is induced during myeloid differentiation, were higher in cells cultured in suspension. There were no significant differences in surface expression of CD34 on the cells after culture, but total CD34 protein, assessed by immunoblotting, was significantly higher in cells cultured on fibronectin. Our data suggest that, in the presence of cytokines, the engagement of VLA-4 and VLA-5 integrins to the fibronectin fragment CH-296 preserves the expression of specific transcription factors associated with primitive stem cell maintenance. In contrast, a lack of integrin engagement leads to the induction of cellular markers associated with myeloid differentiation. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: J. P. O'Rourke and S. A. Ness Alternative RNA Splicing Produces Multiple Forms of c-Myb with Unique Transcriptional Activities Mol. Cell. Biol., March 15, 2008; 28(6): 2091 - 2101. [Abstract] [Full Text] [PDF]

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