2012年9月3日 訊 /生物谷BIOON/ --干細(xì)胞在發(fā)育期間能夠產(chǎn)生大量不同類(lèi)型的細(xì)胞,，并且在維持組織穩(wěn)態(tài)期間能夠替換受損或死亡的細(xì)胞,。因此,，理解干細(xì)胞如何維持自我更新和分化之間的平衡是比較重要的,，特別是考慮到破壞這種平衡能夠?qū)е陆M織退化或癌變,。
果蠅幼蟲(chóng)成神經(jīng)細(xì)胞(neuroblast, NB)一直被廣泛地用作一種模式系統(tǒng)來(lái)研究干細(xì)胞特征,。這些神經(jīng)干細(xì)胞經(jīng)歷多輪重復(fù)的不對(duì)稱(chēng)分裂,，并且基于它們的分裂方式,，它們能夠被分成兩類(lèi)NB。第一類(lèi)NB表達(dá)轉(zhuǎn)錄因子Deadpan(Dpn)和Asense(Ase),，當(dāng)進(jìn)行分裂時(shí),，產(chǎn)生一個(gè)較大的且能夠維持NB性質(zhì)的子細(xì)胞，和一個(gè)較小的神經(jīng)節(jié)母細(xì)胞(ganglion mother cell, GMC),，其中一個(gè)神經(jīng)節(jié)母細(xì)胞能夠產(chǎn)生兩個(gè)有絲分裂后的神經(jīng)元或神經(jīng)膠質(zhì)細(xì)胞,。第二類(lèi)NB并不表達(dá)Ase,，但是也進(jìn)行不對(duì)稱(chēng)分裂,，產(chǎn)生一個(gè)自我更新的NB和一個(gè)較小的中間神經(jīng)祖細(xì)胞(intermediate neural progenitor cell, INP)。中間神經(jīng)祖細(xì)胞經(jīng)歷一個(gè)成熟階段后,，先表達(dá)Ase,，然后表達(dá)Dpn。
在這項(xiàng)新研究中,，研究就人員利用熒光活化細(xì)胞分選法(fluorescence-activated cell sorting, FACS)來(lái)純化大量的來(lái)自果蠅幼蟲(chóng)大腦中的NB和神經(jīng)元,。他們發(fā)現(xiàn)利用FACS純化方法并不影響這些細(xì)胞的活性或獨(dú)特的特征，接著對(duì)這些非常純的細(xì)胞群體進(jìn)行mRNA測(cè)序來(lái)描述NB和神經(jīng)元的轉(zhuǎn)錄組,，結(jié)果鑒定出28個(gè)NB特異性的轉(zhuǎn)錄因子,。對(duì)這些轉(zhuǎn)錄因子進(jìn)行過(guò)表達(dá)和RNA干擾實(shí)驗(yàn)，他們鑒定出Klumpfuss為NB自我更新的調(diào)節(jié)物,。Klumpfuss功能缺失導(dǎo)致NB提前分化,，而它的過(guò)表達(dá)則導(dǎo)致可移植的腦瘤產(chǎn)生。
這些研究為科學(xué)家們?cè)谖磥?lái)進(jìn)行功能性研究奠定基礎(chǔ),，也可能有助于揭示干細(xì)胞丟失它們的生長(zhǎng)控制而產(chǎn)生腫瘤的機(jī)制,。(生物谷Bioon.com)
doi: 10.1016/j.celrep.2012.07.008
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FACS Purification and Transcriptome Analysis of Drosophila Neural Stem Cells Reveals a Role for Klumpfuss in Self-Renewal
Christian Berger, Heike Harzer, Thomas R. Burkard, Jonas Steinmann, Suzanne van der Horst, Anne-Sophie Laurenson, Maria Novatchkova, Heinrich Reichert, Juergen A. Knoblich
Drosophila neuroblasts (NBs) have emerged as a model for stem cell biology that is ideal for genetic analysis but is limited by the lack of cell-type-specific gene expression data. Here, we describe a method for isolating large numbers of pure NBs and differentiating neurons that retain both cell-cycle and lineage characteristics. We determine transcriptional profiles by mRNA sequencing and identify 28 predicted NB-specific transcription factors that can be arranged in a network containing hubs for Notch signaling, growth control, and chromatin regulation. Overexpression and RNA interference for these factors identify Klumpfuss as a regulator of self-renewal. We show that loss of Klumpfuss function causes premature differentiation and that overexpression results in the formation of transplantable brain tumors. Our data represent a valuable resource for investigating Drosophila developmental neurobiology, and the described method can be applied to other invertebrate stem cell lineages as well.
