Brickman M C, Gerhart J C
Department of Molecular and Cell Biology, University of California at Berkeley 94720.
Dev Biol. 1994 Aug;164(2):484-501. doi: 10.1006/dbio.1994.1218.
We have examined the involvement of proteoglycan molecules in the induction of mesodermal tissue in Xenopus laevis embryos. Blastocoelic injections of the enzyme heparitinase at early blastula stages lead to gastrulation defects and to failures in the development of anterior embryonic structures. The period of sensitivity of embryos to this treatment suggests a possible role for these molecules during mesoderm induction. We show that heparan sulfate proteoglycans (HSPGs) and chondroitin sulfate proteoglycans are the predominant sulfated glycoconjugates synthesized in early Xenopus embryos and that HSPGs are degraded by blastocoelic injections of heparitinase. Further, bFGF induction of mesoderm in explants of Xenopus stage 8 embryonic animal cap tissue is blocked by heparitinase but not by Chondroitinase ABC, using three separate criteria of mesoderm induction. Since HSPGs present in blastula animal cap cells are digested by heparitinase under the culture conditions used in the mesoderm-induction assay, we suggest that cell-surface heparan sulfate proteoglycans are required for basic fibroblast growth factor-mediated mesoderm induction.
我们研究了蛋白聚糖分子在非洲爪蟾胚胎中胚层组织诱导过程中的作用。在囊胚早期向囊胚腔注射硫酸乙酰肝素酶会导致原肠胚形成缺陷以及胚胎前部结构发育失败。胚胎对这种处理的敏感时期表明这些分子在中胚层诱导过程中可能发挥作用。我们发现硫酸乙酰肝素蛋白聚糖（HSPGs）和硫酸软骨素蛋白聚糖是非洲爪蟾早期胚胎中合成的主要硫酸化糖缀合物，并且通过向囊胚腔注射硫酸乙酰肝素酶可使HSPGs降解。此外，利用中胚层诱导的三个独立标准，在非洲爪蟾8期胚胎动物帽组织外植体中，硫酸乙酰肝素酶可阻断碱性成纤维细胞生长因子（bFGF）诱导的中胚层形成，但软骨素酶ABC则不能。由于在中胚层诱导试验所用的培养条件下，囊胚动物帽细胞中存在的HSPGs会被硫酸乙酰肝素酶消化，因此我们认为细胞表面硫酸乙酰肝素蛋白聚糖是碱性成纤维细胞生长因子介导的中胚层诱导所必需的。
