The calcineurin-NFAT pathway negatively regulates megakaryopoiesis.

The calcium regulated calcineurin-nuclear factor of activated T cells (NFAT) pathway modulates the physiology of numerous cell types, including hematopoietic. Upon activation, calcineurin dephosphorylates NFAT family transcription factors, triggering their nuclear entry and activation or repression of target genes. NFATc1 and c2 isoforms are expressed in megakaryocytes. Moreover, human chromosome 21 (Hsa21) encodes several negative regulators of calcineurin-NFAT, candidates in the pathogenesis of Down syndrome (trisomy 21)-associated transient myeloproliferative disorder and acute megakaryoblastic leukemia. To investigate the role of calcineurin-NFAT in megakaryopoiesis, we examined wild-type mice treated with the calcineurin inhibitor cyclosporin A and transgenic mice expressing a targeted single extra copy of Dscr1, an Hsa21-encoded calcineurin inhibitor. Both murine models exhibited thrombocytosis with increased megakaryocytes and megakaryocyte progenitors. Pharmacological or genetic inhibition of calcineurin in mice caused accumulation of megakaryocytes exhibiting enhanced 5-bromo-2'-deoxyuridine uptake and increased expression of messenger RNAs encoding CDK4 and G1 cyclins, which promote cell division. Additionally, human megakaryocytes with trisomy 21 show increased proliferation and decreased NFAT activation compared with euploid controls. Our data indicate that inhibition of calcineurin-NFAT drives proliferation of megakaryocyte precursors by de-repressing genes that drive cell division, providing insights into mechanisms of normal megakaryopoiesis and megakaryocytic abnormalities that accompany Down syndrome.

[1]  S. Muljo,et al.  Lin28b Reprograms Adult Bone Marrow Hematopoietic Progenitors to Mediate Fetal-Like Lymphopoiesis , 2012, Science.

[2]  J. Crispino,et al.  Increased dosage of the chromosome 21 ortholog Dyrk1a promotes megakaryoblastic leukemia in a murine model of Down syndrome. , 2012, The Journal of clinical investigation.

[3]  Gerhard Ehninger,et al.  Regulation of fas/fas ligand‐mediated apoptosis by nuclear factor of activated T cells in megakaryocytes , 2012, British journal of haematology.

[4]  W. Alexander,et al.  Characterization of thrombopoietin (TPO)-responsive progenitor cells in adult mouse bone marrow with in vivo megakaryocyte and erythroid potential , 2012, Proceedings of the National Academy of Sciences.

[5]  K. Ravid,et al.  Survivin localization during endomitosis of high ploidy mouse megakaryocytes. , 2010, Blood.

[6]  Anjana Rao,et al.  NFAT, immunity and cancer: a transcription factor comes of age , 2010, Nature Reviews Immunology.

[7]  D. Nižetić,et al.  Tumour angiogenesis is reduced in the Tc1 mouse model of Down Syndrome , 2010, Nature.

[8]  T. Inoue,et al.  Serum thrombopoietin level and thrombocytopenia during the neonatal period in infants with Down's syndrome , 2010, Journal of Perinatology.

[9]  George Q. Daley,et al.  Down syndrome suppression of tumor growth and the role of the calcineurin inhibitor DSCR1 , 2009, Nature.

[10]  T. Minami,et al.  Regulation of Down Syndrome Critical Region 1 expression by Nuclear Factor of Activated T cells in megakaryocytes , 2009, British journal of haematology.

[11]  M. Weiss,et al.  Trisomy 21 enhances human fetal erythro-megakaryocytic development. , 2008, Blood.

[12]  P. Vyas,et al.  Abnormalities in the myeloid progenitor compartment in Down syndrome fetal liver precede acquisition of GATA1 mutations. , 2008, Blood.

[13]  A. Cantor,et al.  Gene Expression Differences Between Fetal Liver-Derived and Adult Bone Marrow-Derived Murine Megakaryocyte Progenitors: Implications for DS-TMD. , 2008 .

[14]  G. Crabtree,et al.  Selective role of calcineurin in haematopoiesis and lymphopoiesis , 2008, EMBO reports.

[15]  T. Ratliff,et al.  megakaryocytes Nuclear factor of activated T cells (NFAT) mediates CD154 expression in , 2010 .

[16]  So-Young Kim,et al.  Extreme thrombocytosis associated with transient myeloproliferative disorder with Down Syndrome with t(11;17)(q13;q21) , 2008, Pediatric blood & cancer.

[17]  E. Fuchs,et al.  NFATc1 Balances Quiescence and Proliferation of Skin Stem Cells , 2008, Cell.

[18]  David Bryder,et al.  Elucidation of the phenotypic, functional, and molecular topography of a myeloerythroid progenitor cell hierarchy. , 2007, Cell stem cell.

[19]  A. Rao,et al.  The NFAT1 Transcription Factor is a Repressor of Cyclin A2 Gene Expression , 2007, Cell cycle.

[20]  A. Kiani,et al.  Expression analysis of nuclear factor of activated T cells (NFAT) during myeloid differentiation of CD34+ cells: regulation of Fas ligand gene expression in megakaryocytes. , 2007, Experimental hematology.

[21]  R. Christensen,et al.  Hematological abnormalities during the first week of life among neonates with Down syndrome: Data from a multihospital healthcare system , 2007, American journal of medical genetics. Part A.

[22]  V. Deutsch,et al.  Megakaryocyte development and platelet production , 2006, British journal of haematology.

[23]  Xin Gao,et al.  NFAT dysregulation by increased dosage of DSCR1 and DYRK1A on chromosome 21 , 2006, Nature.

[24]  F. Macian,et al.  NFAT proteins: key regulators of T-cell development and function , 2005, Nature Reviews Immunology.

[25]  H. Kreipe,et al.  Constitutive expression of the FK506 binding protein 51 (FKBP51) in bone marrow cells and megakaryocytes derived from idiopathic myelofibrosis and non‐neoplastic haematopoiesis , 2004, European journal of haematology.

[26]  F. McKeon,et al.  The threshold pattern of calcineurin-dependent gene expression is altered by loss of the endogenous inhibitor calcipressin , 2003, Nature Immunology.

[27]  Rick B. Vega,et al.  The role of modulatory calcineurin-interacting proteins in calcineurin signaling. , 2003, Trends in cardiovascular medicine.

[28]  I. Weissman,et al.  Characterization of mouse clonogenic megakaryocyte progenitors , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[29]  J. Viola,et al.  NFATC2 transcription factor regulates cell cycle progression during lymphocyte activation: evidence of its involvement in the control of cyclin gene expression , 2002, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[30]  J. Decaprio,et al.  NFATc2-mediated repression of cyclin-dependent kinase 4 expression. , 2002, Molecular cell.

[31]  W. Vainchenker,et al.  Overexpression of FKBP51 in idiopathic myelofibrosis regulates the growth factor independence of megakaryocyte progenitors. , 2002, Blood.

[32]  G. Crabtree,et al.  NFAT Signaling Choreographing the Social Lives of Cells , 2002, Cell.

[33]  M. Le Bousse-Kerdilès,et al.  CD9 and megakaryocyte differentiation. , 2001, Blood.

[34]  E. Olson,et al.  Independent Signals Control Expression of the Calcineurin Inhibitory Proteins MCIP1 and MCIP2 in Striated Muscles , 2000, Circulation research.

[35]  J. Heitman,et al.  Identification and characterization of a highly conserved calcineurin binding protein, CBP1/calcipressin, in Cryptococcus neoformans , 2000, The EMBO journal.

[36]  K. Cunningham,et al.  A conserved family of calcineurin regulators. , 2000, Genes & development.

[37]  D. Longo,et al.  Bcl-2–mediated Drug Resistance: Inhibition of Apoptosis by Blocking Nuclear Factor of Activated T Lymphocytes (NFAT)-induced Fas Ligand Transcription , 1999 .

[38]  P. Musto,et al.  Effect of cyclosporin-A on anemia in idiopathic myelofibrosis. , 1998, Haematologica.

[39]  S. Eliason,et al.  Two NFAT Transcription Factor Binding Sites Participate in the Regulation of CD95 (Fas) Ligand Expression in Activated Human T Cells* , 1997, The Journal of Biological Chemistry.

[40]  P. Wiernik,et al.  Therapeutic effect of cyclosporine A in thrombocytopenia after myeloablative chemotherapy in acute myeloid leukaemia , 1997, Medical oncology.

[41]  E. Price,et al.  Role of kinases and the phosphatase calcineurin in the nuclear shuttling of transcription factor NF-AT4 , 1996, Nature.

[42]  M. Siimes,et al.  Peripheral blood cell counts in infants with Down's syndrome , 1996, Clinical genetics.

[43]  C. Strahlendorf,et al.  Cyclosporin A therapy of immune-mediated thrombocytopenia in children. , 1995, Blood.

[44]  S. Capitani,et al.  Presence and Characteristics of Circulating Megakaryocyte Progenitor Cells in Human Fetal Blood , 1993 .

[45]  S. Capitani,et al.  Presence and characteristics of circulating megakaryocyte progenitor cells in human fetal blood. , 1993, Blood.

[46]  G. Crabtree,et al.  Identification of calcineurin as a key signalling enzyme in T-lymphocyte activation , 1992, Nature.

[47]  G. Crabtree,et al.  Identification of a putative regulator of early T cell activation genes. , 1988, Science.