Glycomics of proteoglycan biosynthesis in murine embryonic stem cell differentiation
Glycomics of proteoglycan biosynthesis in murine embryonic stem cell differentiation
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DOI：
10.1021/pr070446f
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发表时间：
2007-11-01
影响因子：
4.4
通讯作者：
Linfardt, Robert J.
中科院分区：
文献类型：
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作者：
Nairn, Alison V.;Kinoshita-Toyoda, Akiko;Linfardt, Robert J.
糖胺聚糖（Glycosaminoglycans, GAGs）在细胞信号通路的结合和激活中起着关键作用，对发育生物学至关重要。在过去的十年中，GAG的生物合成途径已经被阐明，现在的分析方法使得在少至1000万个细胞中确定GAG组成成为可能。采用糖组学方法检测小鼠胚胎干细胞（mESCs）向胚状体（EBs）和胚胎外内胚层细胞（ExE）分化过程中GAG的含量、组成和编码GAG生物合成酶的转录本水平，以更好地了解GAG在干细胞分化中的作用。透明质酸的合成增加了13倍和24倍，很可能是由于透明质酸合成酶-2的表达增加。从mESC过渡到EB和ExE后，硫酸软骨素(CS)/硫酸皮聚糖（DS）的合成提高了4倍和6倍，硫酸肝素（HS）的合成提高了5倍和8倍。与早期前体合成相关的转录本在很大程度上没有改变，这表明其他因素可以解释GAG合成的增强。CS/DS和HS的组成在分化过程中也发生了变化。有趣的是，随着mESCs向EBs和ExE的分化，CS型E和高硫酸盐HS均增加。CS/DS和HS家族的分化也伴随着2-硫酸化的增强。在mESC分化过程中，核心蛋白的转录水平普遍增加或保持不变。最后，编码GIcNAc-4、6- o -硫基转移酶、c5 -外膜酶和3- o -硫基转移酶等参与GAG晚期生物合成的酶和同工型的转录本也被富集。这些生物合成酶在引入GAG精细结构方面尤为重要，对细胞间通讯、细胞粘附和外内向信号传导至关重要。了解GAG精细结构的变化有助于提高我们对分化干细胞生物学特性的认识。
Glycosaminoglycans (GAGs) play a critical role in binding and activation of growth factors involved in cell signaling critical for developmental biology. The biosynthetic pathways for GAGs have been elucidated over the past decade and now analytical methodology makes it possible to determine GAG composition in as few as 10 million cells. A glycomics approach was used to examine GAG content, composition, and the level of transcripts encoding for GAG biosynthetic enzymes as murine embryonic stem cells (mESCs) differentiate to embryoid bodies (EBs) and to extraembryonic endodermal cells (ExE) to better understand the role of GAGs in stem cell differentiation. Hyaluronan synthesis was enhanced by 13- and 24-fold, most likely due to increased expression of hyaluronan synthase-2. Chondroitin sulfate (CS)/dermatan sulfate (DS) synthesis was enhanced by 4- and 6-fold, and heparan sulfate (HS) synthesis was enhanced by 5- and 8-fold following the transition from mESC to EB and ExE. Transcripts associated with the synthesis of the early precursors were largely unaltered, suggesting other factors account for enhanced GAG synthesis. The composition of both CS/DS and HS also changed upon differentiation. Interestingly, CS type E and highly sulfated HS both increase as mESCs differentiate to EBs and ExE. Differentiation was also accompanied by enhanced 2-sulfation in both CS/DS and HS families. Transcript levels for core proteins generally showed increases or remained constant upon mESC differentiation. Finally, transcripts encoding selected enzymes and isoforms, including GIcNAc-4,6-O-sulfotransferase, C5-epimerases, and 3-O-sulfotransferases involved in late GAG biosynthesis, were also enriched. These biosynthetic enzymes are particularly important in introducing GAG fine structure, essential for intercellular communication, cell adhesion, and outside-in signaling. Knowing the changes in GAG fine structure should improve our understanding the biological properties of differentiated stem cells.