In one of the first studies addressing the role of Dicer1 in hematopoiesis in vivo, floxed Dicer1 alleles were deleted by CRE in lymphocyte-specific protein tyrosine kinase (Lck)-positive cells. In this model, Cre is active at the double-negative (DN) CD4-CD8- T cell developmental stage and results in Dicer1-null CD44-CD25- (DN4), CD4+CD8+ and CD4+CD8-, CD4-CD8- cells (Fig. 1A).18 Dicer1 seems to be essential for the generation and survival of αβ T-cells. However, in the surviving T-cells, Dicer1 is dispensable for CD4+ and CD8+ single positive lineage commitment.18 These results strongly suggest that Dicer1 deletion does not affect normal T-cell lineage-specific gene expression programs. In these cells, the transcriptional repression of centromeric satellite repeats and features of facultative heterochromatin are maintained in the absence of Dicer1,18 suggesting that survival of immature T-cells is regulated directly by a miRNA-controlled mechanism.
Figure 1. Schematic overview of the phenotypic characteristics of different CRE-mediated Dicer1-deletion models in lymphopoiesis (A) HSCs develop via different progenitors toward mature CD4+ or CD8+ single positive cells. The effects of LCK-Cre-mediated Dicer1 deletion are depicted. The apparent level of Dicer1 expression is indicated by the yellow background color (yellow: normal endogenous levels; white: no Dicer1 expression). HSC: hematopoietic stem cells, CLP: common lymphoid progenitor, DN1–3: double negative stage 1 to 3 (CD4-CD8-), DN4: double negative stage 4, DP: double positive CD4+CD8+ cells. Phenotypic characteristics are indicated by the red arrows and lines. Dashed lines indicate less cells than in wild-type situation. (B) See also (A). The effects of CD4-Cre-mediated Dicer1 deletion are depicted. Phenotypic characteristics are indicated by the red arrow and lines. (C) See also (A). The effects of FoxP3-Cre-mediated Dicer1 deletion results in normal numbers of regulatoty T-cells (Tregs) but these cells are functionally aberrant. (D) HSCs develop via indicated progenitors toward mature B-cells. The effects of MB1-Cre-mediated Dicer1 deletion are indicated by the red lines and arrow and result in developmental block from the pro-B-cell to the pre-B-cell stage. Pro-B: earliest stage of progenitor B-cell development, pre-B-cell, precursor stage of B-cell development. (E) See also (D) CD19-Cre-mediated deletion of Dicer1 results in mature B-cells which are functionally aberrant.
The CD4-Cre transgenic mouse model enables investigation of the consequences of Dicer1 deletion at a later stage of T cell development (Fig. 1B). These mice show four major phenotypes: (1) Dicer1 is required for basic cellular processes, such as proliferation and survival, as also proposed by Cobb et al., and therefore Dicer1 deficiency results in decreased number of T-cells.18,19 (2) Dicer1 deletion appears to favor T-cell lineage production from CD4+CD8+ double-positive stage toward CD4+ single-positive peripheral T-cells over CD8+ single-positive cells. However, this phenotype was less obvious from thymic T-cell lineage analysis. This discrepancy may be explained by the fact that CD4-Cre-driven deletion of Dicer1 does not result in complete depletion of all miRNAs, presumably due to high miRNA stability and limited cell divisions of a small fraction of CD4+ T-cells, which may be different for Dicer1-null CD8+ T-cells. (3) Dicer1-null CD4+ T-cells produce increased levels of IFN-γ, a pro-Th1 cytokine, indicating that Dicer1 controls Th1-lineage commitment.19 (4) CD4-Cre; Dicer1fl/fl mice show a more than 2-fold decreased proportion of Foxp3+ regulatory T cells (Treg).20 Interestingly, these mice developed a splenomegaly, and their lymph nodes were severely enlarged at the age of 3 to 4 mo. Moreover, organs such as colon, lung and liver were affected by immune pathology caused by an overactive immune system, which is less severe as compared with Foxp3-knockout mice lacking functional Tregs.20 However, this phenotype suggests that Dicer1-deficient Tregs are functionally aberrant as well.
Two studies revealed the role of Dicer1 more specifically in the function of mature Tregs, using a Foxp3-Cre knock-in mouse (Fig. 1C).21,22 Under steady-state conditions, Foxp3-controlled deletion of Dicer1 has minimal effects on Treg cell development, cellular proliferation and survival in the peripheral compartments.22 However, a diminished fitness of Dicer1-deficient Treg cells in the periphery was observed in a competitive experiment in mice.21 Under inflammatory conditions, the immune-repressive capacity of the mutant Treg cells is markedly reduced and results in rapid fatal autoimmunity and complete failure of immune suppression activity.21,22 Moreover, Dicer1 deletion in Treg cells leads to the progression of fatal lymphoproliferative autoimmune syndrome with an early onset, which is indistinguishably comparable to T-cell-specific Foxp3 deficiency.21 The expression of putative suppressor effector molecules, including CTLA4, IL-10, EBV-induced gene 3 (Ebi-3) and granzyme B, was decreased by still-unidentified miRNA-controlled mechanisms.21 Tregs express a specific set of miRNAs, including miR-223, miR-155 and miR-146, which is distinct from naïve CD4+ T-cells.20 Therefore, the expression of these miRNAs may be under direct or indirect control of the transcription factor Foxp3.20 Identification of the targets that are controlled by these miRNAs in Tregs may provide new insights about the molecular pathways involved in the activity of these cells.
The role of miRNAs in invariant Natural Killer T (iNKT) cells was studied in a mouse strain by Tie2-Cre-mediated disruption of Dicer1.23 The Tie2 kinase is specifically expressed in hematopoietic progenitors and endothelial cells.24 Similar to the immune phenotypes in CD4-Cre;Dicer1fl/fl and Lck-Cre;Dicer1fl/ fl, these mice show reduced numbers of iNKT cells in the thymus, spleen and liver. Moreover, Dicer1 deletion results in developmental abnormalities of iNKT cells.23,25 In addition, Dicer1-deficient peripheral iNKT cell numbers are decreased and displayed profound defects in α-GalCer, phorbol myristate acetate (PMA) and ionomycin-induced cellular activation and production of cytokines such as IL-4 and IFN-γ.23 Together, these data indicate that Dicer1 controls survival at the early T-cell developmental stage. At the later stage, Dicer1 is critical for the balance of Th1/Th2 lineage production and controls functions such as immune-repression and specific cellular activity.
Qin H, Chen F, Huan X, Machida S, Song J, Yuan YA.
Structure of the Arabidopsis thaliana DCL4 DUF283 domain reveals a noncanonical double-stranded RNA-binding fold for protein-protein interaction
16:474-81; PMID: 20106953
; DOI: 10.1261/rna.1965310
Lau PW, Guiley KZ, De N, Potter CS, Carragher B, MacRae IJ.
The molecular architecture of human Dicer
Nat Struct Mol Biol 2012;
19:436-40; PMID: 22426548
; DOI: 10.1038/nsmb.2268
Bernstein E, Caudy AA, Hammond SM, Hannon GJ.
Role for a bidentate ribonuclease in the initiation step of RNA interference
409:363-6; PMID: 11201747
; DOI: 10.1038/35053110
Calabrese JM, Seila AC, Yeo GW, Sharp PA.
RNA sequence analysis defines Dicer’s role in mouse embryonic stem cells
Proc Natl Acad Sci USA 2007;
104:18097-102; PMID: 17989215
; DOI: 10.1073/pnas.0709193104
Cheloufi S, Dos Santos CO, Chong MM, Hannon GJ.
A dicer-independent miRNA biogenesis pathway that requires Ago catalysis
465:584-9; PMID: 20424607
; DOI: 10.1038/nature09092
Cifuentes D, Xue H, Taylor DW, Patnode H, Mishima Y, Cheloufi S, et al.
A novel miRNA processing pathway independent of Dicer requires Argonaute2 catalytic activity
328:1694-8; PMID: 20448148
; DOI: 10.1126/science.1190809
Yang JS, Maurin T, Robine N, Rasmussen KD, Jeffrey KL, Chandwani R, et al.
Conserved vertebrate mir-451 provides a platform for Dicer-independent, Ago2-mediated microRNA biogenesis
Proc Natl Acad Sci USA 2010;
107:15163-8; PMID: 20699384
; DOI: 10.1073/pnas.1006432107
Yang JS, Lai EC.
Dicer-independent, Ago2-mediated microRNA biogenesis in vertebrates
Cell Cycle 2010;
9:4455-60; PMID: 21088485
; DOI: 10.4161/cc.9.22.13958
Benhamed M, Herbig U, Ye T, Dejean A, Bischof O.
Senescence is an endogenous trigger for microRNA-directed transcriptional gene silencing in human cells
Nat Cell Biol 2012;
14:266-75; PMID: 22366686
; DOI: 10.1038/ncb2443
Reinhart BJ, Weinstein EG, Rhoades MW, Bartel B, Bartel DP.
MicroRNAs in plants
Genes Dev 2002;
16:1616-26; PMID: 12101121
; DOI: 10.1101/gad.1004402
Wienholds E, Koudijs MJ, van Eeden FJ, Cuppen E, Plasterk RH.
The microRNA-producing enzyme Dicer1 is essential for zebrafish development
Nat Genet 2003;
35:217-8; PMID: 14528306
; DOI: 10.1038/ng1251
Bernstein E, Kim SY, Carmell MA, Murchison EP, Alcorn H, Li MZ, et al.
Dicer is essential for mouse development
Nat Genet 2003;
35:215-7; PMID: 14528307
; DOI: 10.1038/ng1253
Kanellopoulou C, Muljo SA, Kung AL, Ganesan S, Drapkin R, Jenuwein T, et al.
Dicer-deficient mouse embryonic stem cells are defective in differentiation and centromeric silencing
Genes Dev 2005;
19:489-501; PMID: 15713842
; DOI: 10.1101/gad.1248505
Murchison EP, Partridge JF, Tam OH, Cheloufi S, Hannon GJ.
Characterization of Dicer-deficient murine embryonic stem cells
Proc Natl Acad Sci USA 2005;
102:12135-40; PMID: 16099834
; DOI: 10.1073/pnas.0505479102
Harfe BD, McManus MT, Mansfield JH, Hornstein E, Tabin CJ.
The RNaseIII enzyme Dicer is required for morphogenesis but not patterning of the vertebrate limb
Proc Natl Acad Sci USA 2005;
102:10898-903; PMID: 16040801
; DOI: 10.1073/pnas.0504834102
Cobb BS, Nesterova TB, Thompson E, Hertweck A, O’Connor E, Godwin J, et al.
T cell lineage choice and differentiation in the absence of the RNase III enzyme Dicer
J Exp Med 2005;
201:1367-73; PMID: 15867090
; DOI: 10.1084/jem.20050572
Muljo SA, Ansel KM, Kanellopoulou C, Livingston DM, Rao A, Rajewsky K.
Aberrant T cell differentiation in the absence of Dicer
J Exp Med 2005;
202:261-9; PMID: 16009718
; DOI: 10.1084/jem.20050678
Cobb BS, Hertweck A, Smith J, O’Connor E, Graf D, Cook T, et al.
A role for Dicer in immune regulation
J Exp Med 2006;
203:2519-27; PMID: 17060477
; DOI: 10.1084/jem.20061692
Liston A, Lu LF, O’Carroll D, Tarakhovsky A, Rudensky AY.
Dicer-dependent microRNA pathway safeguards regulatory T cell function
J Exp Med 2008;
205:1993-2004; PMID: 18725526
; DOI: 10.1084/jem.20081062
Zhou X, Jeker LT, Fife BT, Zhu S, Anderson MS, McManus MT, et al.
Selective miRNA disruption in T reg cells leads to uncontrolled autoimmunity
J Exp Med 2008;
205:1983-91; PMID: 18725525
; DOI: 10.1084/jem.20080707
Zhou L, Seo KH, He HZ, Pacholczyk R, Meng DM, Li CG, et al.
Tie2cre-induced inactivation of the miRNA-processing enzyme Dicer disrupts invariant NKT cell development
Proc Natl Acad Sci USA 2009;
106:10266-71; PMID: 19509335
; DOI: 10.1073/pnas.0811119106
Batard P, Sansilvestri P, Scheinecker C, Knapp W, Debili N, Vainchenker W, et al.
The Tie receptor tyrosine kinase is expressed by human hematopoietic progenitor cells and by a subset of megakaryocytic cells
87:2212-20; PMID: 8630381
Fedeli M, Napolitano A, Wong MP, Marcais A, de Lalla C, Colucci F, et al.
Dicer-dependent microRNA pathway controls invariant NKT cell development
J Immunol 2009;
183:2506-12; PMID: 19625646
; DOI: 10.4049/jimmunol.0901361
Koralov SB, Muljo SA, Galler GR, Krek A, Chakraborty T, Kanellopoulou C, et al.
Dicer ablation affects antibody diversity and cell survival in the B lymphocyte lineage
132:860-74; PMID: 18329371
; DOI: 10.1016/j.cell.2008.02.020
Ventura A, Young AG, Winslow MM, Lintault L, Meissner A, Erkeland SJ, et al.
Targeted deletion reveals essential and overlapping functions of the miR-17 through 92 family of miRNA clusters
132:875-86; PMID: 18329372
; DOI: 10.1016/j.cell.2008.02.019
Xu S, Guo K, Zeng Q, Huo J, Lam KP.
The RNase III enzyme Dicer is essential for germinal center B-cell formation
119:767-76; PMID: 22117047
; DOI: 10.1182/blood-2011-05-355412
Bezman NA, Cedars E, Steiner DF, Blelloch R, Hesslein DG, Lanier LL.
Distinct requirements of microRNAs in NK cell activation, survival, and function
J Immunol 2010;
185:3835-46; PMID: 20805417
; DOI: 10.4049/jimmunol.1000980
Sullivan RP, Leong JW, Schneider SE, Keppel CR, Germino E, French AR, et al.
MicroRNA-deficient NK cells exhibit decreased survival but enhanced function
J Immunol 2012;
188:3019-30; PMID: 22379033
; DOI: 10.4049/jimmunol.1102294
Guo S, Lu J, Schlanger R, Zhang H, Wang JY, Fox MC, et al.
MicroRNA miR-125a controls hematopoietic stem cell number
Proc Natl Acad Sci USA 2010;
107:14229-34; PMID: 20616003
; DOI: 10.1073/pnas.0913574107
de Boer J, Williams A, Skavdis G, Harker N, Coles M, Tolaini M, et al.
Transgenic mice with hematopoietic and lymphoid specific expression of Cre
Eur J Immunol 2003;
33:314-25; PMID: 12548562
; DOI: 10.1002/immu.200310005
Alemdehy MF, van Boxtel NG, de Looper HW, van den Berge IJ, Sanders MA, Cupedo T, et al.
Dicer1 deletion in myeloid-committed progenitors causes neutrophil dysplasia and blocks macrophage/dendritic cell development in mice
119:4723-30; PMID: 22353998
; DOI: 10.1182/blood-2011-10-386359
Coley W, Van Duyne R, Carpio L, Guendel I, Kehn-Hall K, Chevalier S, et al.
Absence of DICER in monocytes and its regulation by HIV-1
J Biol Chem 2010;
285:31930-43; PMID: 20584909
; DOI: 10.1074/jbc.M110.101709
Klase Z, Kale P, Winograd R, Gupta MV, Heydarian M, Berro R, et al.
HIV-1 TAR element is processed by Dicer to yield a viral micro-RNA involved in chromatin remodeling of the viral LTR
BMC Mol Biol 2007;
8:63; PMID: 17663774
; DOI: 10.1186/1471-2199-8-63
Lu J, Getz G, Miska EA, Alvarez-Saavedra E, Lamb J, Peck D, et al.
MicroRNA expression profiles classify human cancers
435:834-8; PMID: 15944708
; DOI: 10.1038/nature03702
Kumar MS, Lu J, Mercer KL, Golub TR, Jacks T.
Impaired microRNA processing enhances cellular transformation and tumorigenesis
Nat Genet 2007;
39:673-7; PMID: 17401365
; DOI: 10.1038/ng2003
Kumar MS, Pester RE, Chen CY, Lane K, Chin C, Lu J, et al.
Dicer1 functions as a haploinsufficient tumor suppressor
Genes Dev 2009;
23:2700-4; PMID: 19903759
; DOI: 10.1101/gad.1848209
Lambertz I, Nittner D, Mestdagh P, Denecker G, Vandesompele J, Dyer MA, et al.
Monoallelic but not biallelic loss of Dicer1 promotes tumorigenesis in vivo
Cell Death Differ 2010;
17:633-41; PMID: 20019750
; DOI: 10.1038/cdd.2009.202
Arrate MP, Vincent T, Odvody J, Kar R, Jones SN, Eischen CM.
MicroRNA biogenesis is required for Myc-induced B-cell lymphoma development and survival
Cancer Res 2010;
70:6083-92; PMID: 20587524
; DOI: 10.1158/0008-5472.CAN-09-4736
Wölfler A, Danen-van Oorschot AA, Haanstra JR, Valkhof M, Bodner C, Vroegindeweij E, et al.
Lineage-instructive function of C/EBPα in multipotent hematopoietic cells and early thymic progenitors
116:4116-25; PMID: 20807890
; DOI: 10.1182/blood-2010-03-275404
Jongen-Lavrencic M, Sun SM, Dijkstra MK, Valk PJ, Löwenberg B.
MicroRNA expression profiling in relation to the genetic heterogeneity of acute myeloid leukemia
111:5078-85; PMID: 18337557
; DOI: 10.1182/blood-2008-01-133355
Forbes SA, Bhamra G, Bamford S, Dawson E, Kok C, Clements J, et al. The Catalogue of Somatic Mutations in Cancer (COSMIC). Current protocols in human genetics / editorial board, Jonathan L Haines [et al 2008; Chapter 10:Unit 10 1.
Hill DA, Ivanovich J, Priest JR, Gurnett CA, Dehner LP, Desruisseau D, et al.
DICER1 mutations in familial pleuropulmonary blastoma
325:965; PMID: 19556464
; DOI: 10.1126/science.1174334
Heravi-Moussavi A, Anglesio MS, Cheng SW, Senz J, Yang W, Prentice L, et al.
Recurrent somatic DICER1 mutations in nonepithelial ovarian cancers
N Engl J Med 2012;
366:234-42; PMID: 22187960
; DOI: 10.1056/NEJMoa1102903
Zhang H, Kolb FA, Jaskiewicz L, Westhof E, Filipowicz W.
Single processing center models for human Dicer and bacterial RNase III
118:57-68; PMID: 15242644
; DOI: 10.1016/j.cell.2004.06.017
Gurtan AM, Lu V, Bhutkar A, Sharp PA.
In vivo structure-function analysis of human Dicer reveals directional processing of precursor miRNAs
18:1116-22; PMID: 22546613
; DOI: 10.1261/rna.032680.112
Deng S, Calin GA, Croce CM, Coukos G, Zhang L.
Mechanisms of microRNA deregulation in human cancer
Cell Cycle 2008;
7:2643-6; PMID: 18719391
; DOI: 10.4161/cc.7.17.6597
Merritt WM, Lin YG, Han LY, Kamat AA, Spannuth WA, Schmandt R, et al.
Dicer, Drosha, and outcomes in patients with ovarian cancer
N Engl J Med 2008;
359:2641-50; PMID: 19092150
; DOI: 10.1056/NEJMoa0803785
Zhu DX, Fan L, Lu RN, Fang C, Shen WY, Zou ZJ, et al.
Downregulated Dicer expression predicts poor prognosis in chronic lymphocytic leukemia
Cancer Sci 2012;
103:875-81; PMID: 22320315
; DOI: 10.1111/j.1349-7006.2012.02234.x
Leucci E, Zriwil A, Gregersen LH, Jensen KT, Obad S, Bellan C, et al.
Inhibition of miR-9 de-represses HuR and DICER1 and impairs Hodgkin lymphoma tumour outgrowth in vivo
; PMID: 22310293
; DOI: 10.1038/onc.2012.15
Klusmann JH, Li Z, Böhmer K, Maroz A, Koch ML, Emmrich S, et al.
miR-125b-2 is a potential oncomiR on human chromosome 21 in megakaryoblastic leukemia
Genes Dev 2010;
24:478-90; PMID: 20194440
; DOI: 10.1101/gad.1856210
Meenhuis A, van Veelen PA, de Looper H, van Boxtel N, van den Berge IJ, Sun SM, et al.
MiR-17/20/93/106 promote hematopoietic cell expansion by targeting sequestosome 1-regulated pathways in mice
118:916-25; PMID: 21628417
; DOI: 10.1182/blood-2011-02-336487
Melo SA, Ropero S, Moutinho C, Aaltonen LA, Yamamoto H, Calin GA, et al.
A TARBP2 mutation in human cancer impairs microRNA processing and DICER1 function
Nat Genet 2009;
41:365-70; PMID: 19219043
; DOI: 10.1038/ng.317
Melo SA, Moutinho C, Ropero S, Calin GA, Rossi S, Spizzo R, et al.
A genetic defect in exportin-5 traps precursor microRNAs in the nucleus of cancer cells
Cancer Cell 2010;
18:303-15; PMID: 20951941
; DOI: 10.1016/j.ccr.2010.09.007
Melo SA, Esteller M.
A precursor microRNA in a cancer cell nucleus: get me out of here!
Cell Cycle 2011;
10:922-5; PMID: 21346411
; DOI: 10.4161/cc.10.6.15119
Sun G, Yan J, Noltner K, Feng J, Li H, Sarkis DA, et al.
SNPs in human miRNA genes affect biogenesis and function
15:1640-51; PMID: 19617315
; DOI: 10.1261/rna.1560209
Kawahara Y, Zinshteyn B, Chendrimada TP, Shiekhattar R, Nishikura K.
RNA editing of the microRNA-151 precursor blocks cleavage by the Dicer-TRBP complex
EMBO Rep 2007;
8:763-9; PMID: 17599088
; DOI: 10.1038/sj.embor.7401011
Heale BS, Keegan LP, O’Connell MA.
ADARs have effects beyond RNA editing
Cell Cycle 2009;
8:4011-2; PMID: 19949296
; DOI: 10.4161/cc.8.24.10214
Johnnidis JB, Harris MH, Wheeler RT, Stehling-Sun S, Lam MH, Kirak O, et al.
Regulation of progenitor cell proliferation and granulocyte function by microRNA-223
451:1125-9; PMID: 18278031
; DOI: 10.1038/nature06607