Human CD34-derived myeloid dendritic cell development requires intact phosphatidylinositol 3-kinase-protein kinase B-mammalian target of rapamycin signaling.
Dendritic cells (DCs) are composed of different subsets that exhibit distinct functionality in the induction and regulation of immune responses. The myeloid DC subsets, including interstitial DCs and Langerhans cells (LCs), develop from CD34+ hematopoietic progenitors via direct DC precursors or monocytes. The molecular mechanisms regulating DC development are still largely unknown and mostly studied in mice. Phosphatidylinositol 3-kinase (PI3K) regulates multiple processes in myeloid cells. This study investigated the role of PI3K signaling in the development of human CD34-derived myeloid DCs. Pharmacologic inhibition of PI3K or one of its downstream targets mTOR reduced interstitial DC and LC numbers in vitro. Increased activity of this signaling module by introduction of constitutively active protein kinase B (PKB/c-Akt) increased the yields of human DC precursors in vitro as well as in transplanted beta2-microglobulin-/- NOD/SCID mice in vivo. Signaling inhibition during differentiation did not affect the acquisition of a DC phenotype, whereas proliferation and survival strongly depended on intact PI3K-PKB-mTOR signaling. Interestingly, however, this pathway became redundant for survival regulation upon terminal differentiation, which was associated with an altered expression of apoptosis regulating genes. Although dispensable for costimulatory molecule expression, the PI3K-PKB-mTOR signaling module was required for other important processes associated with DC function, including Ag uptake, LPS-induced cytokine secretion, CCR7 expression, and T cell stimulation. Thus, PI3K-PKB-mTOR signaling plays a crucial role in the development of functional CD34-derived myeloid DCs. These findings could be used as a strategy to manipulate DC subset distribution and function to regulate immunity.
van de Laar
Lianne
L
Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands.
Buitenhuis
Miranda
M
Wensveen
Felix M
FM
Janssen
Harry L A
HL
Coffer
Paul J
PJ
Woltman
Andrea M
AM
D000818:Animals; D018952:Antigens, CD34 / Q000276:immunology / Q000378:metabolism; D017209:Apoptosis / Q000276:immunology; D015153:Blotting, Western; D002454:Cell Differentiation / Q000276:immunology; D002469:Cell Separation; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D022423:Myeloid Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000276:immunology / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000276:immunology / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology*; D058570:TOR Serine-Threonine Kinases
D018952:Antigens, CD34; D047908:Intracellular Signaling Peptides and Proteins; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C546842:MTOR protein, human; C546843:mTOR protein, mouse