|
- 积分
- 0
- 威望
- 0
- 包包
- 4
|
Induction of Pluripotency:
4 _- L2 L3 S9 N& V. @From Mouse to Human0 o: S8 _6 P, X0 L* h
Holm Zaehres1. e3 h1 A* D2 [0 n3 }1 _
and Hans R. Schöler1,# I" m& K& Z8 ^ q8 w( t
* D, a0 h* N! [; v7 ` U7 s' ~
15 i* q/ y9 h# a6 p$ G. c3 k
Max Planck Institute for Molecular Biomedicine, Department of Cell and Developmental Biology, Münster, NRW 48149, Germany
^* D* F, @: x6 G' [+ |! O% L$ i# W*Correspondence: schoeler@mpi-muenster.mpg.de
9 C u4 W1 o, ZDOI 10.1016/j.cell.2007.11.020; v# {0 |6 C; i" _& c H; I& m
In this issue of Cell, Takahashi et al. (2007) transfer their seminal work on somatic cell 1 J! h8 E8 J6 H: Y3 }
reprogramming from the mouse to human. By overexpressing the transcription factor 7 t" `- W% o q- ^
quartet of Oct4, Sox2, Klf4, and c-Myc in adult human fbroblasts, they successfully
. Z. W0 |* d% t, S2 }isolate human pluripotent stem cells that resemble human embryonic stem cells by all , @. X6 s N2 r8 o2 K, a3 v
measured criteria. This is a signifcant turning point in nuclear reprogramming research 8 q' j t- ]% ]! L+ T
with broad implications for generating patient-specifc pluripotent stem cells for research " d2 M8 `. a# x8 K% w: c
and therapeutic applications.
2 Z6 k+ ^; F5 m& A$ TThis year’s three Physiology or Medi-
! J: e1 M& B" J* ccine Nobel Laureates—Martin Evans,
: E _+ L9 h: pMario Capecchi, and Oliver Smithies—7 D' Z: i/ r7 X# N
will be honored in Stockholm in 10 , y6 Q' i) ]/ P
days time for their discovery of DNA 5 w9 ~% i0 |6 v6 m
recombination and the development 4 m7 \) R# P" l, w1 P8 K
of mouse embryonic stem (ES) cell ( R# |: @: T4 X1 ?4 r( P8 p" p7 Q
technology. It was Martin Evans who
' x, p% y0 L _6 Y( K% ]# |! F" O Adiscovered how to make mouse ES
; v0 Z0 z2 o- L6 ]3 N* tcells, enabling any genetic alteration 2 x$ }. N6 Q# Q
to be transferred to the germline and 8 D& e9 v0 D3 ?
hence to the next generation (Evans - i# G1 ~$ x7 b8 T, n E b
and Kaufman, 1981; Martin, 1981). - a. i1 L" r' M: I% g- O
Before this breakthrough, researchers
4 W' H8 J; q: Q+ Ustudied mouse embryonal carcinoma # l: C' c$ U+ B. Q- Y+ t
cells derived from tumors, which ) f- U8 A( ]; f7 }) O; W. F( t* z
could form every mouse cell lineage
: h: f b3 s" g' F. i6 hexcept the germline. Combining DNA * k. C* Z2 L; F5 y% W
recombination and mouse ES cell
- h1 B$ \: B& q- j8 Z' atechnology revolutionized an entire
2 A& S" a; v% H% pfeld of research, forming the basis for
" G' Z& d0 X5 V astudying and understanding the roles
! ]7 d8 M8 I3 _& y! u- Bof numerous genes in embryonic
/ ]6 F! |& m7 Q$ o+ q! qdevelopment, adult physiology, dis-
6 K0 [$ I+ N* w* ?, [ease, and aging. To date, more than
9 E9 ]- \* v* _0 \8 a! m5 @500 mouse models of human disor-1 @8 ?; F/ z; i* f
ders have been generated. Now, with + q# n1 [: m# O1 u; x- V/ x
the study by Takahashi et al. (2007)
$ \: W" t% B, }6 [/ opublished in this issue of Cell, another , ^% R% \8 D( U( p r) n z. c
important revolution is taking place.4 R0 b W0 g" j% Q7 i1 b
Last summer, Takahashi and - |) `, M- r/ N* V( z, x
Yamanaka (2006) stunned the scientifc
. Q* k" X& U% t/ ~; F/ S5 B8 u" tcommunity with their study showing
k* A: F; k% n8 P2 V5 Mmolecular reprogramming of mouse / |- C8 u' a2 t' f- ]3 u
somatic cells into induced pluripotent ( C2 m* H$ J m0 H/ i
stem (iPS) cells using just four factors: 6 G7 ?# ?! a9 I1 A3 G" y) F
Oct4, Sox2, Klf4, and c-Myc. Their ' I2 g" p. [6 Q
elegant but demanding approach of - j4 R; q& S( v i) r" m
screening for a cocktail of factors that
g1 ?+ {, [- ^ B4 Kcould reprogram mouse fbroblasts : X, ?2 ?$ r P! ^6 U8 r* ~7 F [
starting from 24 candidate genes paid 4 I7 ^. Y8 F7 i# g0 E/ `; ]
off with their detailed description of iPS
5 Z" c3 P$ Z- X4 X9 B% ]! rcells, which are almost indistinguish-, @( l5 m; ~2 n3 F% V! H
able from mouse ES cells. As with all 7 h# n2 y( d! {
scientifc discoveries, these exciting % ^2 i& h6 o2 P3 B/ h
fndings had to be reproduced. Sev-
+ B0 q' l& e! p! oeral studies published this year not / u+ M/ g' {4 ?% ^& `/ ?+ O
only reproduced but also extended
+ R: Z# g# T9 E/ W$ [( kthe Takahashi and Yamanaka fndings 1 i0 C1 } U7 R9 D' j5 m* X
by demonstrating the pluripotency and
+ s& W2 q& P* V& } i4 ~. fdifferentiation potential of mouse iPS
2 U% L! l, ~# `) {) v Ecells in rigorous developmental assays ; @% a1 H6 h: O! F3 @" r# o" Y T
(Maherali et al., 2007; Okita et al., 2007;
( d6 J# R3 @3 Y8 ~7 gWernig et al., 2007).3 A) L; S. y( i! Q
In their new study, Takahashi,
9 f, O" i% B4 G# D( h) a% A, H, \Yamanaka, and their colleagues
2 B E& {6 d! x, k(Takahashi et al., 2007) now translate
5 h4 ^8 q& c0 ]' w2 Gtheir remarkable fndings from mouse
% a+ y) g, n; Sto human (see Figure 1). They selected
3 u; ?$ e: X, _3 Cadult human dermal fbroblasts and 9 z0 @, G: R2 n; S$ C
two other human fbroblast popula-
* j ~2 h) g' {+ `1 R5 Wtions (from synovial tissue and neo-
( s a; D- ^) B. e! ` i- ]natal foreskin) from different human - R$ I! w" N9 [' x7 V- g# K: f
donors as their reprogramming target 1 Y, i8 H1 |' d% `/ l7 [. ?
cell populations. They then trans-
% L7 q* E$ N/ ?: r9 ^% Y9 B f3 E+ Cduced the human fbroblast cultures 8 G! a2 Z/ U ~$ ~" ?! Q8 E
with retroviral vectors carrying trans-
& j- c# ?$ W2 J0 ?genes for the human versions of Oct4, ) ^$ F0 U* ]& n$ o0 n( G! b( L
Sox2, Klf4, and c-Myc and cultured
: o9 z: A- }3 M: _& zthe cells under human ES cell culture
& d1 u! a H/ s( p' }2 P Sconditions. Thirty days after transduc-) Z" V& {* U# `6 h% J3 h9 ?
tion, the culture plates were covered
: Y8 Z) i9 z- t4 U1 w9 ~$ Q6 ywith human ES cell-like iPS colonies
8 Q$ Z4 Q/ w- A4 q+ O. G& l3 U(among other colonies), which could
1 O8 a2 d1 R1 _be further propagated and expanded. % n9 n# d9 `) D5 a2 ~. F- T3 ?
The retroviral vectors enabled silenc-$ V& x% n7 X2 t& B
ing of all four transgenes after human ) Q( o0 B" ^+ q1 M: P! V1 w
iPS formation (as found in the mouse + O' \, U/ b y% F# u+ Q, _- h6 [
system) indicating that the iPS cells
0 f9 b+ b* o1 r2 X: D1 C" v# Oare fully reprogrammed and no longer
( y* X6 B9 v; d! x; r! Q, N: qdepend on transgene expression.
% H- X- a* w5 B2 \4 b$ ~5 X9 D$ ]Unlike the mouse study, human
7 o8 t9 Q6 \4 q7 WiPS cells were generated without any
8 n2 m& x0 ~" y% ^" y; J& ugenetic selection procedures. Given 5 Y$ }. ]0 a: ^3 ?
the lower mitotic index of human ES 3 K+ o" H+ T9 `/ V
cells, it is not surprising that the gen-
5 N2 l7 X$ X K5 yeration of human iPS cells takes nota-
% q" {/ u8 ~+ ?9 Y2 y4 ^bly longer than in the mouse system.
. }3 b! b5 p2 Q# s$ n. k: z& \5 cThe authors subjected their human
; ?% w! z U% G/ r4 c7 h* xiPS cells to a panel of assays to com-' m( m+ D1 \$ H7 ` D! l! H: U
pare them with human ES cells. These 0 I+ P0 ?; ^" u6 r' g
assays included morphological stud-& r7 R! d# V9 L1 A1 F
ies, surface-marker expression, epi-5 S5 e/ ?" p4 q) N4 w% k
genetic status, formation of embryoid 9 m* ]; P: D: W# O
bodies in vitro, directed differentia-
9 y8 ^& g! u; A$ Ftion into neural cells and beating car-
/ g0 b* e+ t/ Z) R) g+ Udiomyocytes (according to human ( D' t X4 b% o
ES cell differentiation protocols), and , \/ o+ z; _# Y# [: _9 p- C" }; v
fnally teratoma formation in vivo.
1 z* h* P1 t. K2 z" l" l1 eDNA microarray analysis revealed * v, m" j8 @/ O
the remarkable degree of similar-& v8 O3 v' ^, B8 T& W" @5 K' w2 m
ity between the global gene expres-3 Q* O& O. J3 v% X
sion patterns of human iPS cells and " ^+ X$ r2 \) Y( I. N
human ES cells. Notably, genomic " R, |2 b1 f) _
DNA analysis as well as analysis of 7 v5 |! l7 H8 O( E
short tandem repeats demonstrated , w) s7 D/ E! {5 y
the genetic origin of independent ; D- F" `+ Z0 S2 d+ N: ]! ]. B6 w
human iPS clones from their parental 0 E! p0 a4 I) n( [) {* p
fbroblast populations.% T0 w* V$ _8 ?% w
The derivation of mouse and then 1 z) m! Z! z) I# K7 K; y4 n C1 r
human ES cells (Thomson et al., 1998) y3 N7 i6 u1 n- p) ]( T, c z
as the gold standard of pluripotent / C% q$ Q, r+ C5 j% Q; n" r6 J4 `
stem cell populations has necessarily 1 k2 B: r2 J0 o) w
led to emphasis on differences in the m) }$ j2 @2 H* D" @
regulation of self-renewal between 1 k8 q! g( r \1 g! O k
mouse and human ES cells. For + F. m3 o4 E: B! x) j/ B) E
example, human ES cells depend on
; n4 B/ G* @4 [+ T8 N& K5 zbFGF for self-renewal, whereas their
1 I( U/ k3 u: w/ ]0 ^mouse counterparts depend on the . I1 K3 W8 b& `) _4 K9 p
Lif/Stat3 pathway; BMP is involved in
5 {7 n& e6 ?% H! pmouse ES cell self-renewal, whereas
" r/ B- Y+ A3 c1 q. qin human ES cells it induces differen-( V4 z4 [) |2 F& ~9 @
tiation. Extrinsic factors and signals 7 O( l1 p3 w. ]/ S. a
for maintaining pluripotency may dif-9 z P" U: H+ r/ k( [# {
fer between mouse and human. How-
; L% g/ f: v9 x5 E. Y. _ever, the ability to translate somatic 6 \0 S! n$ }4 t4 J
cell reprogramming from mouse to % C, U1 p& C2 Q! k7 T; G
human using the same transcription 0 Q# r% v( l/ h( h* S
factor quartet further emphasizes the 4 g4 M+ q1 R' G
conserved nature of the Oct4/Sox2
: R* |+ B8 I2 f% n# b: X4 y otranscription factor network that
' ], ?# C- E* r) X- mcontrols self-renewal of mouse and
# \0 @+ h, |3 O# G" Yhuman ES cells (Boyer et al., 2005).
. t8 l5 Q o: h$ s% gGiven that Klf4 and c-Myc are chro-
& V: [3 ]8 N' i) W6 \8 s/ ^matin modifers and can immortal- G& N' ]4 B U
ize cells, one might be able to fnd + {7 K. X- P& S) D
other factors or small molecules that
3 J+ {8 h. A! ~8 E1 t( _could replace these two factors in the ' {- v9 u( S* N; r3 }
cocktail (Yamanaka, 2007). In these 3 N5 a, h6 K, D
studies, the possibility of retroviral
5 w/ h8 f7 [" h5 Cinsertional mutagenesis, resulting $ K) P% q0 S7 m, i: r( X
in the activation of other genes con-2 _8 {; g! z% m3 t7 Y/ E$ E
tributing to reprogramming, cannot 2 e# f0 W0 p- X% M
be excluded, providing an opportu-
6 h8 D( O0 q- k) z7 Anity to potentially identify new repro-+ \/ o. H4 u# @6 x9 l: X" X! w. A
gramming factors beyond the cur-
9 P" w$ O& k i, O5 r: i/ g. Trent quartet. Also, taking a broader 8 ]/ x8 L7 \1 p' v
screening approach for reprogram-
) b8 t2 l* I1 wming human fbroblasts (as Takahashi
% a! p$ p# l8 R" tand Yamanaka did for their mouse ! U: e4 q3 P1 N& O8 H
study) might yield other combinations
. ~ q& j' C* lof reprogramming factors.! Y4 \& e. \. E8 u- V0 E) I" W0 d
Direct reprogramming of somatic
3 Z/ {( }) E7 i/ r3 c/ Jcells to a pluripotent state, thus revers-" Y4 h& s$ G& Y9 V( F' l
ing the developmental arrow of time,
( v* K0 o7 X, ]! y/ v/ zis considered by some to be the “holy
! u+ c; o9 Y/ H/ Y/ Kgrail” of stem cell research. Once the
7 _* o& o4 E8 C3 J8 F4 `9 Oresults in human cells are confrmed,
0 [ c: u7 f: D3 ]. M% othese advances will enable the cre-! { T/ W9 ]9 `
ation of patient-specifc stem cell lines
; _' @6 f1 U0 ?6 |, Fto study different disease mechanisms
0 o; r- L6 m% P% Bin the laboratory. Such cellular models # Z! M( Q- {: ?& Y' ^2 |" e: ~" H) j! }5 T
also have the potential to dramatically
) N4 V' H/ v$ ~7 f3 W9 R& r6 f, F9 sincrease the effciency of drug discov-7 D- J6 l: f$ s1 O/ ?' n0 X0 U- Q
ery and to provide valuable tools for
5 N3 ~1 t( U9 l( p4 Ntoxicology testing. Furthermore, this
' D' f. c3 b' breprogramming system could make
/ Z; S2 d, n2 t8 _& V1 bthe idea of customized patient-specifc
2 t d8 B5 R6 N5 y4 C5 Z0 Jscreening and therapy both possible # b) G( h2 |! ?( }$ I( W& b% [
and economically feasible. Finally, the ! N k. b5 ?# W7 z
work will have a powerful impact on
, f2 k2 h* N) T$ R* c+ r6 X8 Vthe intense debate regarding the moral,
$ x0 K+ K4 O+ K: Wreligious, and political aspects of ES cell ) q2 j3 i* i/ n
research. However, a big mistake now
; z! }- v, l: @! V/ Qwould be to consider human ES cells
( A1 C) m5 {9 eobsolete. There are still many hurdles ' V+ Q q5 ^4 O. j8 X* T4 g# u) |' ?; b
to overcome before we ful ly understand
% Q0 H& g% X; m: q! Bpluripotency and before we have human ' v9 f! D" O7 |7 |6 t9 Z
iPS cells in hand that are suitable for / c* k: X6 D0 O! W# G
therapeutic application. For example, 8 p1 G8 {* {0 u" ^- d
a signifcant proportion of mice derived ' _; c. b1 F1 r1 _' F/ b F" Q
from mouse iPS cells develop tumors ! n" ?/ a) J+ z' ^
due to reactivation of the c-Myc retro-5 _7 ?8 ^: }" v& y: h7 c
virus (Okita et al., 2007) compared to 4 i' g( k6 P6 J: d) G
mice derived from ES cells, which are . n/ F/ m- A" k/ q- h! j" l3 s, `
normal. The search is now on to fnd a 5 ~* B! r9 w1 r: w; E" s
way to reprogram somatic cells without ! n+ h5 ^: C! }: L& T8 H
retroviruses and maybe even using a
0 M ~- t3 \( J7 N. L! A6 L Ucocktail of small molecules. Given this, z- Z. j& ?0 @; k; h+ k; r
it should be emphasized that human 4 W: U5 h7 R0 o
ES cell research is more important than ! G Q3 B7 t6 b
ever for it will shed light on how iPS " T6 p/ L- k+ k- V2 [
cells can best be maintained in their
, Y( m# {5 T/ b% [ v- |. spluripotent state and how they can be
) e& D' A; j8 z3 r% B' ?# Xinduced to differentiate into the cell ( e2 [' P( I" Q( v: S+ h2 Z
lineage of interest. The feld of nuclear
: Y0 B* w, u! Y) R" R9 e& kreprogramming has come a long way
5 V: u8 Y) _3 _3 e, U2 Jfrom the initial nuclear transplantation
7 s: `( R3 e" i1 a: v+ tstudies in frogs 50 years ago, to the
, G) p3 E' N" v7 N7 M& Kbirth of Dolly, the frst mammal cloned Z3 ?" |& W& k; k6 Y8 p
from adult somatic cells (Wilmut et al.,
" [6 o% R/ m5 x& N. f1997), to the fallout from the fabricated
" ]! \3 i, F% y5 r% O/ Ehuman nuclear transfer experiments . W+ H( L/ M! r" y
of several years ago, to the landmark ; V& N9 N! q/ T4 c) l
studies of Takahashi, Yamanaka, and
- |$ V6 P& Y5 z6 N$ q% ^% Ftheir colleagues, frst in mice and now
2 v, R/ ]$ v% z* {in humans.- }5 e0 H- z) I/ h1 w# N6 x
ReFeRences) ?8 O8 e+ M5 m6 b* P$ i
Boyer, L.A., Lee, T.I., Cole, M.F., Johnstone,
; A+ `! X: K5 R4 qS.E., Levine, S.S., Zucker, J.P., Guenther,
3 [6 T+ A- t! ]* M1 r& F _/ ?" MM.G., Kumar, R.M., Murray, H.L., Jenner, R.G.,
7 L9 x- \5 F# X9 a* T% |et al. (2005). Cell 122, 947–956.' c# y# H3 ?2 l0 Q6 F7 q% m+ a, e: g
Evans, M.J., and Kaufman, M.H. (1981). Na-
, d, [/ s" e L1 c$ l# o! V4 ]6 Xture 292, 154–156.# i4 t/ q6 K y! N* S) D& \$ ^
Maherali, N., Sridharan, R., Xie, W., Utikal, J.,
' H v! h# T- `% _$ o, a0 j9 REminli, S., Arnold, K., Stadtfeld, M., Yachenko, ' Y' E. k* P- ?* e( e6 p
R., Tchieu, J., Jaenisch, R., et al. (2007). Cell
8 f) x, i! p/ t& VStem Cell 1, 55–70.
8 |- p- U2 e4 Z/ ^$ S* N8 yMartin, G.R. (1981). Proc. Natl. Acad. Sci. USA & b7 K. O4 @ u5 S
78, 7634–7638./ R! |/ b* \: V5 |2 }: |! `5 c8 F" h& J
Okita, K., Ichisaka, T., and Yamanaka, S. , b; a# \0 J% h$ n
(2007). Nature 448, 313–317.( N a% i1 T% `" {* P9 f$ E- O
Takahashi, K., and Yamanaka, S. (2006). Cell & M. y- j; I: i. ~. H- s4 U
126, 663–676.% j, W: }6 P% e; U$ S! G
Takahashi, K., Tanabe, K., Ohnuki, M., Narita,
; ?2 D, Y+ b: E' t6 _M., Ichisaka, T., Tomoda, K., and Yamanaka, S. ) ]9 T9 B; S- e+ Y
(2007). Cell, this issue.' [3 ~$ G$ y S* P
Thomson, J.A., Itskovitz-Eldor, J., Shapiro,
% J* ]5 W5 Z0 ]* C3 qS.S., Waknitz, M.A., Swiergiel, J.J., Marshall, 5 j! b) _4 s! ], H. P
V.S., and Jones, J.M. (1998). Science 282,
& O$ K. e, a& i5 Q9 U9 U7 @) u1145–1147." h4 T3 n, A: x X6 ?) b! ^$ v( M
Wernig, M., Meissner, A., Foreman, R., Bram-' X* L7 k) X3 }* X/ t
brink, T., Ku, M., Hochedlinger, K., Bernstein, ( \' q* [# j9 P4 e, H
B.E., and Jaenisch, R. (2007). Nature 448,
( H! |; e" X$ A( @% c: L! f: C318–324.5 s- x$ l) q. D
Wilmut, I., Schnieke, A.E., McWhir, J., Kind, % B1 y; F8 k5 ~4 ~/ q' m
A.J., and Campbell, K.H. (1997). Nature 385, ! g4 T+ {1 _* p2 `) \; P) U& c
810–813.# }) {) Y8 L$ ]5 @1 H% o, j
Yamanaka, S. (2007). Cell Stem Cell 1, 39–49. |
|
发表于 2009-4-28 21:35
发表于 2009-5-16 10:41
