DIFFERENTIAL PROCESSING OF PROGLUCAGON BY THE SUBTILISIN-LIKE PROHORMONE CONVERTASES PC2 AND PC3 TO GENERATE EITHER GLUCAGON OR GLUCAGON-LIKE PEPTIDE
DIFFERENTIAL PROCESSING OF PROGLUCAGON BY THE SUBTILISIN-LIKE PROHORMONE CONVERTASES PC2 AND PC3 TO GENERATE EITHER GLUCAGON OR GLUCAGON-LIKE PEPTIDE
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DOI：
10.1074/jbc.270.44.26488
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发表时间：
1995-11-03
影响因子：
4.8
通讯作者：
STEINER, DF
中科院分区：
文献类型：
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作者：
ROUILLE, Y;MARTIN, S;STEINER, DF
胰高血糖素原在胰岛 a 细胞和肠内分泌 L 细胞中的加工方式不同，释放胰高血糖素或胰高血糖素样肽 1-(7-37) (GLP1-(7-37))，这些肽激素在体内具有相反的作用。在之前对转化细胞系（α TC1-6）的研究中，我们证明了kexin/snbtilisin样激素原转化酶PC2（SPC2）负责产生典型的胰高血糖素原加工细胞模式，产生胰高血糖素并留下未加工的整个C端半分子，称为主要胰高血糖素原片段或MPGF（Rouille，Y.，Westermark，G.，Martin，S.g.，斯坦纳 (D. F.) (1994) Proc. Nat1 Acad, Sci. 91, 3242-3246)。在这里，我们使用感染编码高血糖素原的痘苗病毒载体的小鼠垂体 AtT-20 细胞提供证据，表明这些细胞中主要的神经内分泌激素原转化酶 PC3 (SPC3) 再现了肠道 L 细胞加工表型，其中 MPGF 被加工释放两种胰高血糖素相关肽，GLP1 和 GLP2，而含有胰高血糖素的 N 端半分子（高血糖素）仅被部分加工胃泌酸调节素和少量胰高血糖素。此外，在稳定转染PC2的AtT-20细胞（AtT-20/PC2细胞）中，高血糖素被有效地加工成胰高血糖素，这为PC2是负责ar细胞加工表型的酶的结论提供了进一步的支持。在同时表达 PC2 和 PC3 的其他细胞系（STC-1 和 beta TC-3）中，胰高血糖素原也被广泛加工成胰高血糖素和 GLP1-(7-37)，尽管 STC-1 细胞表达较低水平的 PC2 并且将 N 末端结构域加工成胰高血糖素的效率较低。相比之下，表达很少或不表达 PC2 或 PC3 的 GH(4)C(1) 和 COS 7 细胞无法加工胰高血糖素原，除了仅在 GH(4)C(1) 细胞中发生低水平的域间裂解，在体外 PC3 不会在 GLP1 中的单个 Arg 残基处裂解以生成 GLP1-(7-37)（其截短的生物活性形式），表明该裂解可能需要另一种转化酶。
Proglucagon is processed differently in the islet a cells and the intestinal endocrine L cells to release either glucagon or glucagon-like peptide 1-(7-37) (GLP1-(7-37)), peptide hormones with opposing actions in vivo. In previous studies with a transformed or cell Line (alpha TC1-6) we demonstrated that the kexin/snbtilisin-like prohormone convertase, PC2 (SPC2), is responsible for generating the typical a cell pattern of proglucagon processing giving rise to glucagon and leaving unprocessed the entire C-terminal half-molecule known as major proglucagon fragment or MPGF (Rouille, Y., Westermark, G., Martin, S. g., Steiner. D. F. (1994) Proc. Nat1 Acad, Sci. U.S.A. 91, 3242-3246). Here we present evidence, using mouse pituitary AtT-20 cells infected with a vaccinia viral vector encoding proglucagon, that PC3 (SPC3), the major neuroendocrine prohormone convertase in these cells, reproduces the intestinal L cell processing phenotype, in which MPGF is processed to release two glucagon-related peptides, GLP1 and GLP2, while the glucagon-containing N-terminal half-molecule (glicentin) is only partially processed to oxyntomodulin and small amounts of glucagon. Moreover, in AtT-20 cells stably transfected with PC2 (AtT-20/PC2 cells), glicentin was efficiently processed to glucagon, providing further support for the conclusion that PC2 is the enzyme responsible for the ar cell processing phenotype. In other cell lines expressing both PC2 and PC3 (STC-1 and beta TC-3), proglucagon was also processed extensively to both glucagon and GLP1-(7-37), although STC-1 cells express lower levels of PC2 and processed the N-terminal domain to glucagon less efficiently, In contrast, GH(4)C(1) and COS 7 cells, which express very little or no PC2 or PC3, failed to process proglucagon, aside from a low level of interdomain cleavage which occurred only in the GH(4)C(1) cells, In vibro PC3 did not cleave at the single Arg residue in GLP1 to generate GLP1-(7-37), its truncated biologically active form, indicating the likelihood that another convertase is required for this cleavage.