生物谷報道：Duke大學(xué)醫(yī)學(xué)中心的細(xì)胞生物學(xué)科學(xué)家已經(jīng)確定了干細(xì)胞與容納和調(diào)節(jié)它們的特化的“生態(tài)區(qū)位細(xì)胞”（niche cell）之間的一個信號系統(tǒng),。這些發(fā)現(xiàn)使人們對刺激干細(xì)胞自我擴增或分化成一定細(xì)胞類型的信號有了更多的了解。這項研究公布在2005年1月26日的Current Biology雜志上,。
Duke研究組發(fā)現(xiàn)niche cell的調(diào)節(jié)性基因指引干細(xì)胞的基因決定干細(xì)胞的前途——是繼續(xù)擴增還是分化,。Niche和germline干細(xì)胞都具有能夠編碼影響干細(xì)胞分裂的開關(guān)蛋白。干細(xì)胞的過量擴增是癌癥發(fā)生的一個主要原因,，而干細(xì)胞生產(chǎn)力的縮減又與不育,、貧血和免疫系統(tǒng)缺陷有關(guān)。了解干細(xì)胞如何接受分化信息非常重要,，因為任何有潛力的干細(xì)胞臨床應(yīng)用都需要考慮niche cell的作用,。
研究人員分析了germline干細(xì)胞在自我復(fù)制或分化成其它類型細(xì)胞時的特定基因的表達情況。研究人員發(fā)現(xiàn)germline干細(xì)胞的行為受到臨近niche cell的調(diào)節(jié),，而且干細(xì)胞分裂是一個不對稱的過程,。這個研究組確定了三個不同的基因——piwi、pumilio（pum）和bam,，它們能調(diào)節(jié)干細(xì)胞與控制干細(xì)胞命運的niche cell之間的互作,。
研究證明piwi和bam蛋白在germline干細(xì)胞和成包囊細(xì)胞中以互惠模式獨立表達。但是,，它們中的任意一個過表達都會干預(yù)另外一個的作用,。
根據(jù)他們最新的niche cell——germline干細(xì)胞互作模型，niche cell中piwi基因的活化導(dǎo)致了抑制germline干細(xì)胞中bam表達的蛋白質(zhì)的產(chǎn)生,。缺少活性的bam基因會使干細(xì)胞中的pum和其他基因活化,。然后，pum基因抑制與分化有關(guān)的蛋白質(zhì)的制造,。這些分子事件的結(jié)果就是抑制分化,、維持這些細(xì)胞的原來特性,。
美國杜克大學(xué)醫(yī)學(xué)中心的細(xì)胞生物學(xué)家界定了一個信號系統(tǒng)，用于干細(xì)胞之間的交流,。
生物學(xué)家發(fā)現(xiàn)了肺泡細(xì)胞的調(diào)節(jié)基因調(diào)節(jié)干細(xì)胞的演變,。肺泡和干細(xì)胞都有調(diào)節(jié)干細(xì)胞分裂的開關(guān)蛋白基因。本次研究提供了更多關(guān)于信號系統(tǒng)是如何指導(dǎo)干細(xì)胞分裂亦或分化的信息,。“理解干細(xì)胞是如何接受分化指令是十分關(guān)鍵的,，將來的臨床應(yīng)用都是使用干細(xì)胞的分化細(xì)胞-肺泡細(xì)胞。”研究人員說,。
“我們發(fā)現(xiàn)干細(xì)胞的行為被其周圍的肺泡細(xì)胞調(diào)節(jié),。肺泡細(xì)胞提供了干細(xì)胞發(fā)揮功能的環(huán)境。”本次研究的負(fù)責(zé)人說,，“干細(xì)胞分裂是一個非對稱過程,。分裂后一個新生細(xì)胞仍和肺泡細(xì)胞黏附，仍作為干細(xì)胞,，另一則和肺泡細(xì)胞分開,，開始新的命運。”（http://www.bioon.com/）
Biologists Find Stem Cell Regulator
Study defines signaling system between stem cells and the niche cells that harbor them
A signaling system between stem cells and specialized niche cells that harbor and regulate the stem cells has been defined by cell biologists at Duke University Medical Center.
They found that regulatory genes from niche cells give instructions to genes in stem cells to determine the stem cells' future path. Both niche cells and stem cells have genes that produce proteins that act as on/off toggles for stem cell division.
This study offers more insight into the signals that instruct stem cells to either create more copies of themselves or to change into another cell type. It's vital to understand how stem cells receive their instructions to differentiate because any future clinical use of stem cells must also take into account the role of niche cells, the Duke team said.
"We found that stem cell behavior is regulated by the neighboring niche cells, which provide an idyllic hideaway essential to the functioning of the stem cells," research leader Haifan Lin said in a prepared statement.
"Stem cell division is an asymmetric process. After division, one daughter cell remains attached to the niche cell and thus remains as a stem cell, whereas the other daughter cell is detached from niche cells and will thus acquire a different fate," Lin said.
The study appears in the Jan. 26 issue of Current Biology.
