Gabreëls B A, Sonnemans M A, Seidah N G, Chrétien M, van Leeuwen F W
Netherlands Institute for Brain Research, Amsterdam.
Brain Res. 1992 Jul 10;585(1-2):275-82. doi: 10.1016/0006-8993(92)91218-4.
The homozygous Brattleboro rat (di/di), displaying a hypothalamic form of diabetes insipidus, synthesizes a vasopressin (VP) precursor with an abnormal C-terminus. The phenotypic expression of coexisting peptides in mutant magnocellular VP cells shows a differential pattern. 7B2 is one of the peptides which is not detectable, whereas there is a clear galanin expression. During postnatal life a small but increasing number of solitary post-mitotic VP neurons of the di/di rat undergoes a switch to a heterozygous phenotype. Here we report the presence of 7B2 and galanin in these heterozygous cells, which suggests that for the expression of 7B2, but not for that of galanin, the relative amount of mutant VP precursor must be diminished. Possible underlying mechanisms for this differential phenotypic expression of coexisting peptides are compartmentalization of precursor synthesis within the RER or a competition for sites involved in the translocation of the functionally reduced RER.
纯合的布拉德福德大鼠（di/di）表现出下丘脑型尿崩症，其合成的血管加压素（VP）前体的C末端异常。突变的大细胞VP细胞中共存肽的表型表达呈现出差异模式。7B2是其中一种无法检测到的肽，而甘丙肽的表达则很明显。在出生后的生命过程中，di/di大鼠中一小部分但数量不断增加的处于有丝分裂后状态的孤立VP神经元会转变为杂合表型。我们在此报告这些杂合细胞中存在7B2和甘丙肽，这表明对于7B2的表达而言，但对于甘丙肽的表达并非如此，突变VP前体的相对量必须减少。共存肽这种差异表型表达的可能潜在机制是粗面内质网（RER）内前体合成的区室化，或者是对功能降低的RER转运所涉及位点的竞争。
