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???????????? ?????????????? ????????? ????????????
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?? Ig????? (?)Ig???????--?????? ?????Ig???4???????
????? 2????Mr?????(H?)?2????Mr?????(L?)
??????????????????????????????,??????????????????I
g???????????????,?Ig??????? ????????????????????
???????????
4
(No Transcript)
5
(?)???????
??Ig????????????????????,??????????(V?)????(C?),
V ????????????,?C??????????????V??C???????????????
?,???????????????????,?????60-70??????,???????????
???????????,??????110-120???????
???2????,?VL?CL2????????4-5??????,????4-5?????VH?C
H1?CH2?CH3?CH4?
6
?VL?VH?????????????(??????????????????,?????????
???)??,??????????????????CH1?CH2?CH3?CH4??????????
???,?????CL?????,?????????,????????Ig????????????
????????????????????????????????,???????????,???
??,?VH?VL??V???,??????????????????
7
(?)?????
1.?? ??????213?214????????????,Mr?22000,??????2?
???,?VL?CL????????????N??1-109???(VL)????,??110-21
4???(CL)????????????C?????????????,???( ? ?)???(
?? )???Ig?????????????,????????Ig??????????????
8
2.?? ??????446????????????,Mr?77000-80000,??????
4-5????,?VH?CH1?CH2?CH3?CH4????????,?????,?N????12
0????????(VH),??????????120???????(CH)???????????
???Ig??C????????????????????????5?,???a?µ?d?e??,??
???IgG?IgA?IgM?IgD?IgE????
9
(?)???
?Ig??CH1?CH2?????????,?????????,?????Cys?Pro??,?
????????? ????????????Pro?????,???????????????a???
ß???????,??????????????,??????,??????,?????????,??
?????????????
10
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(?)?????????? (?)??????????
11
(?)??????????
1.???????? ????????????6C2,????????????????????
C??C????,????????V??V?????, V???????250?,???V???1-
95?96????????????????J???????95?96-110????,?????5?
J???( J?1- J?5 )?, J?3????,?????????,??????????,??
?J???????????????????V???????????,
J??????????,??V????J??????????????(?2)?
12
2.??????? ????????????,??????2p12?V???????100?,J
??????5?,?????????????????V??J???,???VJ????(?V3?J2
???V3J2????),?????V?,????DNA????RNA?,???RNA??,VJ??
???C???????mRNA,?????(?3)
13
3.??????????? ??????????????????16?22q11,DNA????
?????,???3??????V??J??C????????V??????2?,
J??????3????V??????10?, J??????6?,
J??V?????????V?, C???????C????????V???????,??V????
?????,??????????????????????,???????5????????????
?????????,?2?V????4?J????????????????????,????V???
??2?J?-C????????V?1?J?3C?3?J?1C?1??(?2)
14
(No Transcript)
15
(?)??????????
???????V????V?D?J??????,??????C?????????????????
????,??V????????????????????????14q32?12F1???????V
?????VH?JH??????????????250-1000?VH????,???100-100
0?VH????,????N?98????,?????H1?H2????10?DH????,????
?20?DH,DH???????V???3????H3,??????DNA?VH??JH????DH
???????????????????,???12-15?????JH?????????,???DH
???????C????????7kb?????4?V????16-21????,????????V
??????????VH?DH?JH??????????????????
16
(No Transcript)
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????????????JH?????????????????,????????????DNA?
200kb,???CH?????????,????????????C?e?Cf??????(?4)?
??µ?d?C?????JH????,???Cd???????????C???,???e?/?a??
Ig??C????3-4????,?IgG?IgA?IgD?CH?3?,?IgM?IgE??4?,?
??????????????(?5),?µ??4????????4???????,?????????
?????????,?C????????1??2????????????????,??????2??
????????????????????C??DNA????????????????????????
??????
18
??????
(?)V????? (?)12-36bp?? (?)???? (?)??????? (?)??VDJ
???VJ??????? (?)??????
19
(?)V?????
Ig?????????????,???????V????????????????????????
??????,??DNA?????????(?6) ?B????????,????????,??
?????????,?????DH?JH????,??????DH-JH?VH???????????
????VH-DH-JH??????,?????????V????????????,??????V?
?????????????,?????2????????????(?????????)?
??
20
(No Transcript)
21
(?)12-36bp??
1983?Tonegawa?????????????,??????VH?VL??????????
JH?JL????,?????DH?????????????????(?7)?????????J??
3??7??????????GTGTCAC,???V????5?????CACAGTG?????
2???????J????3????????23?????????????????TGTTTTTG
G,??V?????????5????12???????ACAAAAACC???(?8)?????
??????121?231????????????,???12-23???
??
22
(?)????
?V???????J??????????????????????????????????,???
???????V??????????J??????,???V?J??????????,???????
,???????V?J????,????V?J??????DNA???????????????
??
23
(No Transcript)
24
(?)???????
?B?????????,???Ig??????,???????B??????IgM?/?IgD,
??DNA?????,????VHDHJH?????????CH??????,?B?????????
????????C??????Ig,????????????
25
(No Transcript)
26
(No Transcript)
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(No Transcript)
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(No Transcript)
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(No Transcript)
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Honjo?Kataoka???????????,????CH??????? 5
Cµ-Cd-C?3-C?1-C?2b-C?2a-Ce-Ca3 ??CH???????
5Cµ-Cd-C?3-C?1-C?2-C?4-Ce-Ca2 3???????????????,?
???????,DNA???C?(?Cµ)????,????VDJ??????C?VK
(C?3),????DNA????(?????Cµ ?????C?3
?????Cd??)???Cµ ????????????????
??
31
(?)??VDJ???VJ???????
Ig??????V????2??3???????,??????VH?VL?DH?JH?JL???
??????,????????????????V??????????(?1)
??B????????????????????????,???V????????????DH????
???????????,?????????Ig???DH?????????H3,????V?D?J?
?????????Ig?????????
??
32
??B?????????????????????????,???V????????????DH?
??????????????,?????????Ig???DH?????????H3,???V?D?
J??????????Ig?????????
33
(?)??????
???DH-JH?VH-DHJH?VL-JL???????????????,?????????I
g????,? (1)????????????????????????,????????,???
??????????????????(?10(1))? (2)??????,???????????
??????(?10(2))?????????????????????????10???????DH
-JH?VH-DH???????????,??V????????????????????????,?
????????????????????
??
34
(3)????????????????????,?????????(?10(3)) ??,?????
?????????,?????????Ig???
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?????????????

(Schlissel MS, Stanhope-Baker P. ,1997) Antigen
receptor genes are assembled from their component
gene segments by a highly regulated series of
site-specific DNA recombination reactions known
as V(D)J recombination. Proteins encoded by the
RAG1 and RAG2 genes are responsible for the
recognition and double-stranded cleavage of a
highly conserved DNA sequence flanking all
rearranging gene segments. It remains uncertain
how this common lymphoid recombinase is targeted
to distinct loci in developing B and T cells and
to specific loci at successive stages of
lymphocyte(????) development. This review
considers evidence that DNA sequences which
regulate the transcription of antigen receptor
genes also regulate the recombination reaction by
determining the accessibility of individual loci
to the V(D)J recombinase.
36
(Cedar H, Bergman Y. 1999) Rearrangement of
antigen(??) receptors in the immune system is
mediated through the action of complex enhancers
which function in both a developmentally
stage-specific and a cell-type-specific manner to
demethylate DNA, open chromatin structure and
tether the recombination machinery to one
preferred allele at each locus.
37
IgE antibody plays an important role in allergic
diseases. IgE synthesis by B cells requires two
signals. The first signal is delivered by the
cytokines IL-4 or IL-13, which target the
Cepsilon gene for switch recombination. The
second signal is delivered by interaction of the
B cell surface antigen CD40 with its ligand
(CD40L) expressed on activated T cells. This
activates deletional switch recombination.
Bacharier LB, Geha RS.(2000 )review the molecular
mechanisms of IL-4 and CD40 signaling that lead
to IgE isotype switching and discuss the
implications for intervening to abort or suppress
the IgE antibody response.
38
V(D)J recombination is required not only for
receptor diversification but also for
lymphocyte(????) development. At a molecular
level, these recombination events are directed by
conserved DNA sequences flanking all antigen
receptor gene segments that function as
recognition(??) signals for a single recombinase
activity. Despite these shared features,
recombination events are controlled at the levels
of stage- and tissue-specificity. Primary
research focus is to dissect the mechanisms that
regulate assembly of antigen receptor loci by
rendering certain gene segments accessible to a
common V(D)J recombinase.
39
Oltz EM.have found that transcriptional promoters
are critical cis-acting regulatory elements for
targeting efficient recombination of chromosomal
gene segments. And have also demonstrated that
activation of NF-kappaB signaling in precursor B
cells is required for global regulation of Ig
light chain gene assembly.
40
V(D)J recombination events within the locus are
regulated as a function of developmental stage
and cell lineage during T-lymphocyte(????)
differentiation in the thymus. The process of
V(D)J recombination is regulated by cis-acting
elements that modulate the accessibility of
chromosomal substrates to the recombinase.
Krangel MS, Hernandez-Munain C and etc(1998
)evaluate how the assembly of transcription
factor complexes onto enhancers, promoters and
other regulatory elements within the TCR
alpha/delta locus imparts developmental control
to VDJ delta and VJ alpha rearrangement events.
Furthermore, we develop the notion that within a
complex locus such as the TCR alpha/delta locus,
highly localized and region-specific control is
likely to require an interplay between positive
regulatory elements and blocking or boundary
elements that restrict the influence of the
positive elements to defined regions of the locus.
41
The joining(??,??) of T cell receptor (TCR) and
immunoglobulin (Ig) gene segments through the
process of V(D)J recombination occurs in a
lineage-specific and developmental-stage-specific
way during the early stages of lymphocyte(????)
development. Such developmental regulation is
thought to be mediated through the control of
gene segment accessibility to the recombinase.
The transcriptional enhancers Edelta and Ealpha
have been implicated as critical regulators that,
in conjunction with other cis-acting elements,
confer region-specific and developmental-stage-spe
cific changes in gene segment accessibility
within TCR alpha/delta locus chromatin. Current
work suggests that they may do so by functioning
as regional modulators of histone acetylation.
42
V(D)J recombination is the process that generates
the diversity among T cell receptors and is one
of three mechanisms that contribute to the
diversity of antibodies in the vertebrate immune
system. The mechanism requires precise cutting of
the DNA at segment boundaries followed by
rejoining of particular pairs of the resulting
termini. The imprecision of aspects of the
joining reaction contributes significantly to
increasing the variability of the resulting
functional genes. Signal sequences target DNA
recombination and must participate in a highly
ordered protein-DNA complex in order to limit
recombination to appropriate partners. Two
proteins, RAG1 and RAG2, together form the
nuclease that cleaves the DNA at the border of
the signal sequences. Additional roles of these
proteins in organizing the reaction complex for
subsequent steps are explored.
43
(No Transcript)
44
(Kim DR, Park SJ, Oettinger MA. )V(D)J
recombination is a site-specific gene
rearrangement process that contributes to the
diversity of antigen receptor repertoires. Two
lymphoid-specific proteins, RAG1 and RAG2,
initiate this process at two recombination signal
sequences. Due to the recent development of an in
vitro assay for V(D)J cleavage, the mechanism of
cleavage has been elucidated clearly. The RAG
complex recognizes a recombination signal
sequence, makes a nick at the border between
signal and coding sequence, and carries out a
transesterification reaction, resulting in the
production of a hairpin structure at the coding
sequence and DNA double-strand breaks at the
signal ends. RAG1 possesses the active site of
the V(D)J recombinase although RAG2 is essential
for signal binding and cleavage. After DNA
cleavage by the RAG complex, the broken DNA ends
are rejoined by the coordinated action of DNA
double-strand break repair proteins as well as
the RAG complex. The junctional variability
resulting from imprecise joining of the coding
sequences contributes additional diversity to the
antigen receptors.
45
( Fugmann SD., 2001 )RAG1 and RAG2 are the
key components of the V(D)J recombinase(???)
machinery that catalysesthe somatic gene
rearrangements of antigen receptor genes during
lymphocyte(????) development. In the first step
of V(D)J recombination--DNA cleavage--the RAG
proteins act together as an endonuclease(?????)
to excise the DNA between two individual gene
segments. They are also thought to be involved in
the subsequent DNA joining step. In vitro, the
RAG proteins catalyze the integration of the
excised DNA element into target DNA completing a
process similar to bacterial transposition. In
vivo, this reaction is suppressed by an unknown
mechanism.
46
(Huang J, Muegge K.,2001) IL-7 is a key factor
for lymphoid development, and it contributes to
V(D)J recombination at multiple loci in
immune-receptor genes. IL-7 signal transduction,
involving gamma(c) and Jak3, is required for
successful recombination at the TCR-gamma locus.
IL-7 signaling controls the initiation phase of
V(D)J recombination by controlling access of the
V(D)J recombinase to the locus. In the absence of
IL-7, the TCR-gamma locus is methylated(???) and
packaged in a repressed form of chromatin(???)
consisting of hypoacetylated histones. IL-7
signaling likely increases the acetylation(???)
state of the nucleosomal core histones resulting
in an "open" form of chromatin. This opening
leads to a higher accessibility for the
transcription machinery and increased
accessibility of the Rag heterodimer that
performs the cleavage of DNA.
47
Molecular regulation of class switch
recombination to IgE through epsilon germline
transcription. (Maizels N.,2000 )A new mechanism
for regulation in the immune system has been
identified a cytidine deaminase is critical for
both class switch recombination and somatic
hypermutation, revealing an unanticipated link
between these two processes.( Sale JE, Bemark M,
Williams GT and etc,2001) Following antigen
encounter, two distinct processes modify
immunoglobulin genes. The variable region is
diversified by somatic hypermutation while the
constant region may be changed by class-switch
recombination.
48
(Oettgen HC.,2000)In allergic(????) responses, B
cells are driven to undergo an immunoglobulin
isotype switch, shifting from IgM to IgE
synthesis. This process involves the
rearrangement of germline DNA in the
immunoglobulin heavy-chain locus and is
stimulated by cytokines (IL-4 and IL-13) and CD40
activation(??). It is now evident that
cytokine-induced 'germline' epsilon-RNA
transcripts associate with DNA in the genomic
switch region (S epsilon) to form DNA-RNA hybrid
structures, which target nucleases in for
deletional switch recombination. Alterations in
cytokine production and signaling affect the
efficiency of this process and are associated
with inherited predisposition to allergy.
49
(Lieber M.2000) Recent work indicates that
mutations in a cytidine deaminase
homologue(???,????????????,???) ablate both
immunoglobulin class switch recombination and
somatic hypermutation.
50
?1?????????????????
??
????? (????) ?? H ?? ??
????? (????) ?? H ? ?
V?? 100-1000 100 10
D?? 20 0 0
J?? 6 5 6
VJ(D)??????-?????? 12000-120000 500 60
H ? 6 106-6 107
H ? 7.2 105- 7.2 106