干细胞之家 - 中国干细胞行业门户第一站

 

 

搜索
干细胞之家 - 中国干细胞行业门户第一站 干细胞之家论坛 干细胞行业新闻 华裔科学家证实精子重编程中一个重要的步骤
朗日生物

免疫细胞治疗专区

欢迎关注干细胞微信公众号

  
查看: 25397|回复: 3
go

华裔科学家证实精子重编程中一个重要的步骤 [复制链接]

Rank: 7Rank: 7Rank: 7

积分
6084 
威望
6084  
包包
18316  

优秀版主 金话筒 优秀会员

楼主
发表于 2011-9-26 13:56 |只看该作者 |倒序浏览 |打印
本帖最后由 naturalkillerce 于 2011-9-26 14:04 编辑 2 H5 N# ^6 t. _# o2 |! t6 a; s

" j( G/ T* ^- }

华裔科学家证实精子重编程中一个重要的步骤


0 Z; F: C1 N) x; x( Dnaturalkillerce导语:华裔科学家Yi Zhang与Azusa Inoue教授开发一种高分辨率的染色技术,能够让研究人员在生命早期发育阶段可视化精子和卵子染色体,结果表明精子DNA经历从甲基到羟甲基的化学转换,卵子DNA则没有这种经历,同时也证实羟甲基标签是随着时间流逝被动消失的,是在DNA复制分离时被稀释掉的。现编译如下:: {/ X! _  f9 y2 [- U* j* |

# S2 `$ r# c: j) I+ `. f0 c研究背景:
) F! I1 O2 o, L9 K0 x当精子与卵子相遇时,精子细胞上的化学标签必须清除,这样才能产生新的人类生命。这些化学标签去除的一个方式就是去甲基化,即移除细胞DNA上分布的特异性化学标签或者甲基。尽管科学家们10年前就知道这个现象,但是这种“重编程”实际如何发生依然是个谜。
9 D# q3 {& y* Q7 f2 _& c) O
: |' E, I9 P% o' h研究成果:
7 b; I  b- s/ Y* E) d5 D以前研究已经证实精子DNA上的甲基标签在完全消失前能够转化为羟甲基。这一研究成果于2011年9月22日在线发表在Science杂志上,表明在去甲基化较后的步骤中,这些化学标签的消失并不是由酶催化的一个主动过程,相反是一个被动的过程。
2 ~# H& [: ?( y( c: f2 Y/ r* t/ c% y8 q5 Q5 b* V* e5 a
该研究的主要作者Yi Zhang是北卡罗来纳大学凯南杰出的生物化学和生物物理学教授,也是北卡罗来纳大学Lineberger癌症中心的成员,同时也是霍华德•休斯医学研究所(Howard Hughes Medical Institute)的一名研究员。- z% x5 X, i" d
* r8 |, A$ o/ r1 G) S/ i
Zhang与该研究论文共同作者Azusa Inoue教授开发一种技术能够让研究人员在生命的最初阶段可视化染色体---一种线状的含有细胞DNA的结构体。通过这种高分辨率的染色技术,Zhang能够比较生命早期发育阶段的精子和卵子染色体中的甲基标签和羟甲基标签水平。
9 Q' r5 J7 h% z8 q% \6 O
; E4 S5 h# U' T/ i2 y* S/ l1 f他们的发现证实了他们已经知道的事情,即精子DNA经历从甲基到羟甲基的化学转换,而卵子DNA则没有,同时也证实羟甲基标签是随着时间流逝被动消失的,是在DNA复制分离时被稀释掉的,而有机体则从一个细胞阶段发育到二-四细胞阶段。
* \' R4 |6 ?3 L
0 h+ f: Q- R+ e  v3 w3 n研究意义:
) ^3 c) j+ G, R; h2 F意义之一:这项研究已阐明去甲基化中的一个关键步骤,从而给干细胞研究人员在试图重编程成体细胞来模仿干细胞的治疗和自我更新性质时提供了关键性的信息。
: @4 p8 x. K' ^0 q' ~' F6 k7 }% m( n$ L! b& |4 U3 {2 J
意义之二:这种分子事件的生物学功能到目前仍不清楚,但是研究人员试图把它揭示出来。但是,他们相信这一事件在发育肯定是非常重要的,因为它是在这些细胞转化为任何特异性细胞类型之前发生的。
  H3 _4 _% i+ a. W6 ~0 S) h& T  I: R% s" c5 r0 l
不足之处:
) o6 `8 V7 v6 ?7 k& F就像研究意义中说的那样,尽管知道这种分子事件非常重要,但是它的生物学功能到目前仍不清楚,而且这一发现的临床意义仍不清晰,因为研究人员仍不知道为什么男性DNA经历这一初始的转化,而女性DNA则不用。这可能是与包装精子和卵子DNA的不同蛋白结构(染色质)有关系。Zhang和其他人在这一领域正在进行大量研究。
* J' K! Y3 ?, E+ ]+ k0 }7 z) f  H9 [
2 A; {0 `7 p! y; h3 T& M论文信息:
1 C: R/ L" Y6 U2 bAzusa Inoue and Yi Zhang. Replication-Dependent Loss of 5-Hydroxymethylcytosine in Mouse Preimplantation Embryos. Science, 22 September 2011 DOI:10.1126/science.1212483( L" k1 k" ?$ g6 v* q3 j% Y
http://www.sciencemag.org/conten ... /21/science.1212483
附件: 你需要登录才可以下载或查看附件。没有帐号?注册
已有 2 人评分威望 包包 收起 理由
细胞海洋 + 50 + 100 精品文章
uyunbilig + 10 + 10 精品文章

总评分: 威望 + 60  包包 + 110   查看全部评分

Rank: 7Rank: 7Rank: 7

积分
6084 
威望
6084  
包包
18316  

优秀版主 金话筒 优秀会员

沙发
发表于 2011-9-26 14:08 |只看该作者
回复 naturalkillerce 的帖子
+ W! _0 |7 ~* n7 g$ T0 O. N( ?- B
2 \/ j/ R$ ~/ y$ ]# c2 J+ ~8 R

Important Step in Sperm Reprogramming Identified


+ r+ d* g! `' eScienceDaily (Sep. 22, 2011) — When sperm meets egg, the chemical instructions that tag sperm cells must be erased so that human life can start anew. One way these instructions are erased is through demethylation, the removal of specific chemical tags or methyl groups that dot the underlying DNA of cells. Though scientists have known about this phenomenon for a decade, exactly how such "reprogramming" occurs has proved elusive.
8 j' P7 j0 M5 V: G0 _( W; x# Z
' v5 U3 x4 p5 Y1 ZNow, a study from the University of North Carolina at Chapel Hill School of Medicine has illuminated a key step of demethylation, giving stem cell researchers critical information as they try to reprogram adult cells to mimic the curative and self-renewing properties of stem cells.
# D) _5 n% W2 ]. r5 ~+ X
* V3 G* q: l) U7 _1 m8 ~Previous research had shown that the methyl tags on sperm DNA are converted to their chemical cousin, hydroxymethyl, before disappearing completely. The current finding, published online in the September 22, 2011, issue of Science(ScienceExpress), suggests that the disappearance of these chemical tags in the later steps of demethylation is not an active process catalyzed by an enzyme but is rather a passive process./ [3 b* k. n+ j$ R: Z; A" i( l
3 T' ]: |" J' Y- @4 {
"The biological function of this molecular event is not known yet, we are still trying to figure it out," said senior study author Yi Zhang, Ph.D., Kenan distinguished professor of biochemistry and biophysics at UNC and an investigator of the Howard Hughes Medical Institute. "But we do believe it must be important for development, because it happens before the cells committed to any specific cell types." Zhang is also a member of the UNC Lineberger Comprehensive Cancer Center.
# C! F3 j/ [1 i+ Y
/ \# V1 W( m3 k$ y. qZhang's postdoctoral fellow and co-author Azusa Inoue, Ph.D., developed a technique that enabled him to visualize chromosomes -- the threadlike bodies that contain the cell's DNA -- at the earliest stage of life. Through a high resolution staining technique, he was able to compare the levels of methyl tags and hydroxymethyl tags in sperm and egg chromosomes at early developmental stages of life.6 \$ G( q0 ?8 \6 ]# e. N# p
2 {2 @% O- X3 P2 m) ~, _, x
Their findings confirmed what they already knew -- that the sperm DNA goes through a chemical conversion from methyl to hydroxylmethyl while the egg DNA did not. But it also found something new -- that the hydroxymethyl tags disappeared passively over time, being diluted out as the DNA divided and the organism doubled from the one-cell to the two- and four-cell stage.
$ ]% `( N& q! y' m3 A2 @+ ^' p0 h# \& n( j
The clinical implications of the finding are still not clear, Zhang says, because researchers still don't know why male DNA undergoes that initial conversion when female DNA does not. It may have something to do with the differential protein structure (chromatin) that packages the DNA of sperm and egg. This is a notion Zhang and others in the field are actively pursuing.' B# p: \3 M3 }7 l# L7 F: \

0 h0 ~9 R4 p1 L9 \* y' aThe research was funded by the Howard Hughes Medical Institute and the National Institutes of Health. (http://www.sciencedaily.com/releases/2011/09/110922141917.htm)

Rank: 2

积分
90 
威望
90  
包包
255  
藤椅
发表于 2011-10-6 10:13 |只看该作者
本帖最后由 细胞海洋 于 2011-10-6 10:39 编辑 # ]) n. x" S1 [8 ~* g$ ]
) h9 S  ?* t& j( _5 k$ f9 O
附件: 你需要登录才可以下载或查看附件。没有帐号?注册
已有 1 人评分威望 包包 收起 理由
细胞海洋 + 2 + 10 极好资料

总评分: 威望 + 2  包包 + 10   查看全部评分

Rank: 3Rank: 3

积分
312 
威望
312  
包包
719  

优秀会员

板凳
发表于 2011-10-8 14:12 |只看该作者
干细胞之家微信公众号
谢谢分享!
‹ 上一主题|下一主题
你需要登录后才可以回帖 登录 | 注册
验证问答 换一个

Archiver|干细胞之家 ( 吉ICP备2021004615号-3 )

GMT+8, 2025-6-11 18:02

Powered by Discuz! X1.5

© 2001-2010 Comsenz Inc.