Table Of Content290
Current Topics
in Microbiology
and Immunology
Editors
R.W.Compans,Atlanta/Georgia
M.D.Cooper,Birmingham/Alabama
T.Honjo,Kyoto·H.Koprowski,Philadelphia/Pennsylvania
F.Melchers,Basel·M.B.A.Oldstone,LaJolla/California
S.Olsnes,Oslo·M.Potter,Bethesda/Maryland
P.K.Vogt,LaJolla/California·H.Wagner,Munich
H. Singh and R. Grosschedl (Ed.)
Molecular Analysis
of B Lymphocyte
Development
and Activation
With28Figures,15inColor
ProfessorDr.HarinderSingh
DepartmentofMolecularGeneticsandCellBiology
HowardHughesMedicalInstitute
TheUniversityofChicago
5841S.MarylandAve.N112
Chicago,IL60637,USA
e-mail:[email protected]
ProfessorDr.RudolfGrosschedl
Max-Plank-InstituteofImmunobiology
DepartmentofCellularandMolecularImmunology
St(cid:1)beweg51
79108Freiburg,Germany
e-mail:[email protected]
CoverillustrationbyR.Sciammas(thisvolume)
LibraryofCongressCatalogCardNumber72-152360
ISSN0070-217X
ISBN3-540-23090-4SpringerBerlinHeidelbergNewYork
This work is subject to copyright. All rights are reserved, whether the whole or part of the
material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,
recitation,broadcasting,reproductiononmicrofilmsorinanyotherway,andstorageindata
banks.Duplicationofthispublicationorpartsthereofispermittedonlyundertheprovisions
oftheGermanCopyrightLawofSeptember9,1965,initscurrentversion,andpermissionfor
usemustalwaysbeobtainedfromSpringer-Verlag.Violationsareliableforprosecutionunder
theGermanCopyrightLaw.
SpringerisapartofSpringerScience+BusinessMedia
springeronline.com
(cid:2)Springer-VerlagBerlinHeidelberg2005
PrintedinGermany
The use of general descriptive names, registered names, trademarks, etc. in this publication
doesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom
therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse.
Product liability: The publishers cannot quarantee that accuracy of any information about
dosageandapplicationcontainedinthisbook.Inevery individualcasetheusermustcheck
suchinformationbyconsultingtherelevantliterature.
Editor:Dr.RolfLange,Heidelberg
Deskeditor:AnneClauss,Heidelberg
Productioneditor:AndreasG(cid:3)sling,Heidelberg
Coverdesign:design&productionGmbH,Heidelberg
Typesetting:St(cid:1)rtzGmbH,W(cid:1)rzburg
Printedonacid-freepaper 27/3150/ag –543210
Preface
The B lymphocyte lineage represents a leading system for exploring mo-
lecularmechanismsthatunderliecellfatespecification,differentiationand
cellular activation. In the past five years major advances have been
achieved in the analysis of early B cell development, AID dependent class
switchrecombinationaswellassomatichypermutationandBlimp-1regu-
latedplasma celldifferentiation. Manyof these findings andtheir implica-
tions are covered in this volume. Two emergent areas of research that are
includedinthecontributionsfocusonthepre-BCRandIkaros-familypro-
teins. The pre-BCRisanunusualmoleculardevicethat is usedto execute
acriticaldevelopmentalcheckpoint intheBlineage. Itsmechanismofac-
tion in relation to the pre-TCR and the mature antigen receptors (BCR,
TCR)isofconsiderableinterest. Ikaros-familyproteinsappeartofunction
via recruiting target genes to domains of centromeric heterochromatin in
the nucleus. Initially discovered in lymphocytes, they represent a novel
system of gene regulation via nuclear compartmentalization. Finally, the
volume includes a chapteronWnt signaling in lymphopoiesis. Analysis of
this evolutionallyconservedpathway which regulates cellular proliferation
anddifferentiationindiversedevelopmentalcontextsbenefitedenormous-
ly fromthediscoveryoftheLEF/TCFfamilyoffactors inlymphocyticlin-
eages.
ThisvolumeisdedicatedtothememoryofEugeniaSpanopoulou,acol-
league and a highly valued member of our scientific community. It con-
tains a chapter on the biochemistry of V(D)J recombination that Eugenia
co-authoredwithDavidSchatz.
Obituary
Eugenia Spanopoulou was an extraordinary person and scientist. Her
enormousintelligenceandenergysparkedimportantscientificdiscoveries,
and vaulted her to a point of breathtaking potential—a potential abruptly
erased at the age of 37 with the crash of Swissair flight 111 on September
3,1998.Lostwithher wereherhusband,AndrewHodtsev,andyoungson,
Platon.
Eugeniawaspassionatelyinterestedinunderstandingthemolecularba-
sis of development and chose as her model system the development of B
and T lymphocytes. She began by studying the transcriptional regulation
oftheTcell-specificgene,Thy-1,asagraduatestudentinFrankGrosveld(cid:4)s
labatMillHill,London.Thereafter,sheturnedherattentiontothetopicof
V(D)J recombination, first as a postdoctoral fellow with David Baltimore
at the Whitehead Institute in Cambridge, Massachusetts and subsequently
inherownlaboratoryatMountSinaiSchoolofMedicineinNewYorkCity.
Eugenia made fundamental discoveries concerning the biochemical mech-
anism of this reaction, and how defects in its central enzymatic compo-
nents,RAG1andRAG2,canleadtoahumanseverecombinedimmunode-
ficiency disorder, known as Omenn syndrome. At the time of her death,
shehadbeenaHowardHughesMedicalInstituteinvestigatorforlessthan
ayear,buthadalreadyassembledalaboratoryof15peopleworkingonan
extensive array of topics in early lymphocyte development and V(D)J re-
combination.
Eugenia lived each moment of her life with an intensity fitting for the
cityinwhichshelived.LikeManhattan,shesleptlittle.Sheexpectedagreat
dealof herself,andonlyalittlelessfromthosewithwhomsheworked.Eu-
geniaalso hadhigh expectationsfor thescientificprocessandwasoutspo-
ken in her praise or condemnation of those who met or fell short of those
expectations. She was quick to form an opinion and devoted herself fero-
ciously tofriendshipsandhypotheses.
Perhapsthegreatesttestimony toEugeniaistheaffectionandreverence
felt for her by the members of her lab. While this stemmed in no small
part from predictable sources—her keen mind and broad knowledge—it
found its deepest source in Eugenia(cid:4)s ability to transmit, by example and
word, her love of a life of learning and exploration. Sandro Santigata, a
graduatestudentinEugenia(cid:4)slab,capturedthiseloquentlyatthememorial
serviceforEugeniaandAndrew,whenhesaid:
VIII Obituary
“If you have ever been spellbound by a great statue, enraptured by its
strengthandvitality,enthralledbyitspurity,purposeandgraceanduplift-
ed by the sense of hope that it sparks within your soul, then you have al-
readyunderstoodwhyIadoredEugenia.Shesimplyembodiedtheidealis-
tic principles that form the core of a dedicated graduate student(cid:4)s heart.
And to see these values materialized in the form of one(cid:4)s mentor can be
nothingshortofinspirational.”
List of Contents
GeneRegulatoryNetworksOrchestratingBCellFateSpecification,
Commitment,andDifferentiation
K.L.Medina·H.Singh....................................... 1
Helix-Loop-HelixProteinsinLymphocyteLineageDetermination
B.L.Kee................................................... 15
Ikaros-FamilyProteins:InSearchofMolecularFunctions
DuringLymphocyteDevelopment
B.S.Cobb·S.T.Smale........................................ 29
BiochemistryofV(D)JRecombination
D.G.Schatz·E.Spanopoulouy................................. 49
Thepre-BcellReceptorinBCellDevelopment:
RecentAdvances,PersistentQuestionsandConservedMechanisms
M.R.Clark·A.B.Cooper·L.D.Wang·I.Aifantis ................. 87
TranscriptionalControlofBCellActivation
L.M.Corcoran ............................................. 105
ExpressionofMHCIIGenes
G.Drozina·J.Kohoutek·N.Jabrane-Ferrat·B.M.Peterlin ......... 147
ClassSwitchRecombination:AnEmergingMechanism
A.L.Kenter ................................................ 171
Blimp-1;ImmunoglobulinSecretion
andtheSwitchtoPlasmaCells
R.Sciammas·M.M.Davis.................................... 201
WntSignalinginLymphopoiesis
A.Timm·R.Grosschedl ..................................... 225
SubjectIndex ............................................. 253
List of Contributors
(Theiraddressescanbefoundatthebeginningoftheirrespectivechapters.)
Aifantis,I. 87 Kohoutek,J. 147
Clark,M.R. 87 Medina,K.L. 1
Cobb,B.S. 29 Peterlin,B.M. 147
Cooper,A.B. 87 Schatz,D.G. 49
Corcoran,L.M. 105 Sciammas,R. 201
Davis,M.M. 201 Singh,H. 1
Drozina,G. 147 Smale,S.T. 29
Grosschedl,R. 225 Spanopoulou,E.y 49
Jabran-Ferrat,N. 147 Timm,A. 225
Kee,B.L. 15 Wang,L. 87
Kenter,A.L. 171
CTMI(2005)290:1--14
(cid:2)Springer-Verlag2005
Gene Regulatory Networks Orchestrating
B Cell Fate Specification, Commitment,
and Differentiation
)
K.L.Medina·H.Singh( )
HowardHughesMedicalInstitute,TheUniversityofChicago,
Chicago,IL60637,USA
[email protected]
1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 SpecificationandCommitmenttotheBCellFate. . . . . . . . . . . . . 2
3 RegulationofIgGeneRearrangementandPre-BCellDifferentiation. . 9
4 ConclusionsandPerspectives . . . . . . . . . . . . . . . . . . . . . . . . 11
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Abstract TheBcelldevelopmentalpathwayrepresentsaleadingsystemfortheanal-
ysis of regulatory circuits that orchestrate cell fate specification, commitment, and
differentiation. We review the progress that has been achieved inthe identification
andcharacterizationofregulatorycomponentsofsuchcircuits,includingtranscrip-
tionfactors,chromatinmodifyingproteins,andsignalingmolecules.Acomprehen-
sive developmental model is proposed that invokes sequentially acting regulatory
networks which dictatethe generationofBcells frommultipotential hematopoietic
progenitors.
1
Introduction
Cellfatespecificationinthehematopoieticsystemappearstoinvolvethe
resolution of multi-lineage programs of gene expression and is enabled
by the concomitant activation and silencing of lineage-specific subsets
of genes. Signaling molecules, chromatin modifying complexes and
transcription factors can be regarded as components of gene regulatory
networks,whichorchestratecellfatespecification,commitmentanddif-
ferentiation. Two cytokine receptors (Flk2/Flt3 and IL-7R) and six tran-
scription factors (PU.1, Ikaros, E2A, Bcl11a, EBF, and Pax-5) are critical
for thedevelopmentofBcellprecursors(Georgopoulosetal.1994;Scott
2 K.L.Medina·H.Singh
et al. 1994; Bain etal. 1994; Zhuang etal. 1994; Nutt et al. 1997; Peschon
et al. 1994; Lin and Grosschedl 1995; Mackarenhtschian et al. 1995; Liu
etal.2003).ArecentstudyhasalsodemonstratedaroleforamicroRNA
in the generation of B cells from stem cells (Chen et al. 2004). It is well
established that B cell development proceeds through an ordered set of
intermediates that can be identified on the basis of cell surface markers
and the expression of a characteristic set of B lineage genes encoding
componentsoftheBcellantigenreceptor.Accompanyingthesedevelop-
mental transitions are alterations in the nuclear compartmentalization
and chromatin structure of immunoglobulin (Ig) heavy and light chain
loci resulting intheir stage-specific DNA rearrangements. Inthis review
we attempt to assemble molecular circuits that regulate key transitions
in B cell development, integrating the roles of signaling molecules, tran-
scriptionfactors,andchromatin-modifyingproteins.
2
Specification and Commitment tothe B CellFate
Allbloodcellsarederivedfromararepopulationof hematopoieticstem
cells (HSCs). Considerable progress is being made in analyzing the mo-
lecular circuitry that instructs stem cell self-renewal vs differentiation.
Importantly, HSC express at low levels many lineage-specific genes re-
flectingadevelopmentally poisedstate(Terskikhetal.2003).Thediffer-
entiating progeny of the HSC is the multipotential progenitor (MPP) or
short-term repopulating cell. In contrast to the HSC, the MPP has only
limited ability to generate all of the blood lineages (Wiesmann et al.
2000). Expression of CD27 within the stem cell compartment correlates
with loss of long-term stem cell function in vivo and permits resolution
of MPPs from stem cells. Single-cell RT-PCR analyses demonstrate that
bothHSCandMPPsexhibitwidermultilineagegeneexpressionpatterns
than their progeny, the lymphoid and myeloid progenitors, which ex-
press more restricted sets of genes (Miyamoto et al. 2002). The molecu-
larmechanismsbywhichmultipotentialprogenitorsfinetunetheirgene
expression patterns resulting ultimately in specification of distinct cell
fatesisanareaofintenseresearchindevelopmentalbiology.
Results from several studies have recently established that the molec-
ularcircuitrydriving thelymphoidvsmyeloidcellfatedecisions isacti-
vated within the MPP population. One set of studies stemmed from the
observationthatasmallfractionofcellswithintheMPPpopulationwere
uniquely sensitive to a negative regulator of B and T lymphopoiesis, es-
