Cell Surface Heparan Sulfate Proteoglycans Mediate the Internalization of PDX-1 Protein
Cell Surface Heparan Sulfate Proteoglycans Mediate the Internalization of PDX-1 Protein
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DOI：
10.3727/000000008783906892
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发表时间：
2008-01
影响因子：
3.3
通讯作者：
M. Ueda;S. Matsumoto;S. Hayashi;N. Kobayashi;H. Noguchi
中科院分区：
文献类型：
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作者：
M. Ueda;S. Matsumoto;S. Hayashi;N. Kobayashi;H. Noguchi
虽然胰岛移植是治疗1型糖尿病的一种有前途的治疗选择，但缺乏合适的供体组织仍然是一个主要障碍。存在于导管上皮内的胰腺干细胞/祖细胞已被用于产生人胰岛样簇，但没有有效的策略来促进祖细胞分化为胰岛素产生细胞。先前的研究报道，外源性PDX-1蛋白可以转导到胰腺干/祖细胞中，并诱导细胞分化为胰岛素产生细胞，而不需要基因转移技术。本研究提供了细胞膜硫酸乙酰肝素蛋白聚糖是细胞外PDX-1内化所需的遗传和生化证据。肝素（一种可溶性糖胺聚糖（GAG））抑制PDX-1内化，而硫酸软骨素A、B和C仅引起非常有限的抑制。用肝素酶-III处理细胞表现出受损的PDX-1内化，而用软骨素酶ABC或用软骨素酶AC处理在抑制PDX-1内化方面完全无效。还检查了源自CHO K1细胞且GAG生物合成缺陷的不同突变细胞系。PDX-1内化在pgs A-745突变体细胞和pgs B-618细胞中均显著降低，pgs A-745突变体细胞缺乏启动GAG合成的酶，而pgs B-618细胞产生的GAG量约为野生型细胞合成的15%。这些数据表明，细胞表面硫酸乙酰肝素蛋白多糖是PDX-1内化所必需的，并且PDX-1蛋白转导可能是在不需要基因转移技术的情况下诱导胰腺干/祖细胞中胰岛素表达的有价值的策略。
Although islet transplantation is a promising therapeutic option for the treatment of type 1 diabetes, the shortage of suitable donor tissues remains a major obstacle. Pancreatic stem/progenitor cells residing within the ductal epithelium have been used to generate human islet-like clusters, but there is no efficient strategy for facilitating differentiation of progenitor cells into insulin-producing cells. A previous study reported that exogenous PDX-1 protein can be transduced into pancreatic stem/progenitor cells and induce differentiation of the cells into insulin-producing cells without requiring gene transfer technology. This study provides genetic and biochemical evidence that cell membrane heparan sulfate proteoglycans are required for extracellular PDX-1 internalization. Heparin, one of the soluble glycosaminoglycans (GAGs), inhibited PDX-1 internalization, while chondroitin sulfate A, B, and C caused only very limited inhibition. Cell treatment with heparinase-III demonstrated impaired PDX-1 internalization, while treatment with chondroitinase ABC, or with chondroitinase AC, was completely ineffective in inhibiting PDX-1 internalization. Different mutant cell lines originating from CHO K1 cells and defective in GAG biosynthesis were also examined. PDX-1 internalization was significantly reduced in both pgs A-745 mutant cells, which are defective in a enzyme that initiates GAG synthesis, and pgs B-618 cells, which produce about 15% of the amount of GAGs synthesized by wild-type cells. These data indicate that cell-surface heparan sulfate proteoglycans are required for PDX-1 internalization and that PDX-1 protein transduction could be a valuable strategy for inducing insulin expression in pancreatic stem/progenitor cells without requiring gene transfer technology.