據(jù)8月份發(fā)表于PloS Biology雜志上的一篇文章,，科學(xué)家最新識(shí)別了一種細(xì)胞，該細(xì)胞在果蠅胚胎形成期能夠改變身份?？茖W(xué)家稱這種細(xì)胞為"mixer cells"，通過模型研究,，科學(xué)家發(fā)現(xiàn)它們有助于緩解組織張力,。這項(xiàng)發(fā)現(xiàn)揭示了組織如何適應(yīng)胚胎形成過程中的變化，或能開啟再生醫(yī)學(xué)研究的新方向,。
多細(xì)胞生物由很多不同類型的細(xì)胞組成（皮膚,，肝臟或神經(jīng)細(xì)胞等）。它們?cè)醋杂诜翘厥饣脑技?xì)胞,，最終經(jīng)分化機(jī)制而特殊化,。這些細(xì)胞會(huì)形成獨(dú)立的層，使得器官能夠正確形成,。通過分層,，細(xì)胞能夠執(zhí)行兩種功能：一旦分化它們會(huì)保持自己特殊的身份，而特定層上的細(xì)胞仍然會(huì)聚集,，不會(huì)與其他層的細(xì)胞混合在一起,。
研究人員觀察了果蠅晶胚的背閉合行為（dorsal closure）。在果蠅胚胎形成的關(guān)鍵時(shí)期,，兩個(gè)表層匯合并關(guān)閉,，這就像傷口的修復(fù)。通過觀察背閉合行為時(shí)期的晶胚,，研究人員發(fā)現(xiàn)有一種細(xì)胞能夠承擔(dān)兩種角色,。事實(shí)上，這類細(xì)胞能夠進(jìn)行兩種身份的轉(zhuǎn)變,。身份的變化或者說細(xì)胞粘性在先前的一些研究中研究人員已經(jīng)有所了解,，該過程會(huì)在疾病發(fā)生過程或其他一些特定環(huán)境下發(fā)生。而在該案例中,，細(xì)胞粘性并沒有在這些已知的前提下發(fā)生,。
研究人員表示，這類細(xì)胞是由特定基因控制的,，該基因同樣參與成年果蠅的組織再生,。另外這些基因會(huì)形成JNK信號(hào)通路，該通路在脊椎動(dòng)物中也存在,。這個(gè)遺傳控制的細(xì)胞粘性機(jī)制是一種獨(dú)特的細(xì)胞行為,，科學(xué)家是首次在胚胎形成過程中觀察到這種現(xiàn)象,。
一旦分化，這類細(xì)胞會(huì)從一個(gè)層面移動(dòng)到另一個(gè)層面,，甚至穿過那些被認(rèn)為是不能穿越的屏障,。此外，隨著細(xì)胞遷移數(shù)量的增加,，組織張力也變大,。科學(xué)家發(fā)現(xiàn)在一種未知的過程下,，混合細(xì)胞的粘性機(jī)制能夠感應(yīng)臨近細(xì)胞的介入活動(dòng),，因此組織能夠適應(yīng)胚胎形成過程中的張力變化。
這項(xiàng)研究描述了在胚胎形態(tài)發(fā)生過程中一種新穎的細(xì)胞粘性機(jī)制,，或能為康復(fù)過程的細(xì)胞機(jī)制研究提供新的思路,。（生物谷Bioon.com）
生物谷推薦原文出處：
PloS Biology, DOI: 10.1371/journal.pbio.1000390
JNK Signalling Controls Remodelling of the Segment Boundary through Cell Reprogramming during Drosophila Morphogenesis
Melanie Gettings1#, Fanny Serman1#, Rapha?l Rousset1, Patrizia Bagnerini2, Luis Almeida3, Stéphane Noselli1*
Segments are fundamental units in animal development which are made of distinct cell lineages separated by boundaries. Although boundaries show limited plasticity during their formation for sharpening, cell lineages make compartments that become tightly restricted as development goes on. Here, we characterize a unique case of breaking of the segment boundary in late drosophila embryos. During dorsal closure, specific cells from anterior compartments cross the segment boundary and enter the adjacent posterior compartments. This cell mixing behaviour is driven by an anterior-to-posterior reprogramming mechanism involving de novo expression of the homeodomain protein Engrailed. Mixing is accompanied by stereotyped local cell intercalation, converting the segment boundary into a relaxation compartment important for tension-release during morphogenesis. This process of lineage switching and cell remodelling is controlled by JNK signalling. Our results reveal plasticity of segment boundaries during late morphogenesis and a role for JNK-dependent developmental reprogramming in this process.
