Expression analysis of nuclear factor of activated T cells (NFAT) during myeloid differentiation of CD34+ cells: regulation of Fas ligand gene expression in megakaryocytes.
OBJECTIVE
Nuclear factor of activated T cells (NFAT) transcription factors belong to a family of five proteins that are primarily known for their central role in the regulation of inducible gene expression in activated T cells. Little information exists on the expression or function of NFAT family members in hematopoietic cells, during myeloid differentiation or in myeloid cells.


METHODS
In the present study, we establish a comprehensive expression profile of all five NFAT family members in human CD34+ hematopoietic progenitor cells and during their ex vivo differentiation into neutrophil, eosinophil, erythroid, and megakaryocytic lineages. Based on the observed expression pattern, the role of NFAT in Fas ligand gene expression in megakaryocytes was investigated.


RESULTS
When CD34+ cells are induced to differentiate into neutrophil granulocytes, expression of all NFAT family members is rapidly suppressed. In contrast, regulation of NFAT expression during eosinophil, erythroid, and megakaryocytic differentiation follows a family member- and lineage-specific pattern. Most obviously, transcript and protein levels of NFATc4 are specifically upregulated about 10-fold during megakaryocytic differentiation, while they remain almost undetectable in neutrophil, eosinophil, and erythroid cells. As a first evidence for a functional role for NFAT in this cell type, NFAT was found to be strictly required for both the constitutive and inducible expression of the Fas ligand gene in megakaryocytes.


CONCLUSIONS
The expression pattern of NFAT and its family member- and lineage-specific regulation during myeloid differentiation will prompt further studies on the role of NFAT in myeloid cells, particularly in megakaryocytes.
Kiani
Alexander
A
Department of Medicine I, Dresden University of Technology, Dresden, Germany. alexander.kiani@uniklinikum-dresden.de
Kuithan
Hanna
H
Kuithan
Friederike
F
Kyttälä
Satu
S
Habermann
Ivonne
I
Temme
Achim
A
Bornhäuser
Martin
M
Ehninger
Gerhard
G
D018952:Antigens, CD34 / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D019070:Cell Lineage / Q000502:physiology; D053222:Fas Ligand Protein / Q000187:drug effects / Q000235:genetics*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D008533:Megakaryocytes / Q000187:drug effects / Q000502:physiology*; D022423:Myeloid Cells / Q000502:physiology*; D050778:NFATC Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000502:physiology
D018952:Antigens, CD34; D053222:Fas Ligand Protein; D050778:NFATC Transcription Factors; D012333:RNA, Messenger; D015759:Ionomycin