Polans A S, Witkowska D, Haley T L, Amundson D, Baizer L, Adamus G
R. S. Dow Neurological Sciences Institute, Legacy-Good Samaritan Hospital, Portland, OR 97209, USA.
Proc Natl Acad Sci U S A. 1995 Sep 26;92(20):9176-80. doi: 10.1073/pnas.92.20.9176.
Recoverin is a member of the EF-hand family of calcium-binding proteins involved in the transduction of light by vertebrate photoreceptors. Recoverin also was identified as an autoantigen in the degenerative disease of the retina known as cancer-associated retinopathy (CAR), a paraneoplastic syndrome whereby immunological events lead to the degeneration of photoreceptors in some individuals with cancer. In this study, we demonstrate that recoverin is expressed in the lung tumor of a CAR patient but not in similar tumors obtained from individuals without the associated retinopathy. Recoverin was identified intially by Western blot analysis of the CAR patient's biopsy tissue by using anti-recoverin antibodies generated against different regions of the recoverin molecule. In addition, cultured cells from the biopsy tissue expressed recoverin, as demonstrated by reverse transcription-PCR using RNA extracted from the cells. The immunodominant region of recoverin also was determined in this study by a solid-phase immunoassay employing overlapping heptapeptides encompassing the entire recoverin sequence. Two linear stretches of amino acids (residues 64-70, Lys-Ala-Tyr-Ala-Gln-His-Val; and 48-52, Gln-Phe-Gln-Ser-Ile) made up the major determinants. One of the same regions of the recoverin molecule (residues 64-70) also was uniquely immunopathogenic, causing photoreceptor degeneration upon immunization of Lewis rats with the corresponding peptide. These data demonstrate that the neural antigen recoverin more than likely is responsible for the immunological events associated with vision loss in some patients with cancer. These data also establish CAR as one of the few autoimmune-mediated diseases for which the specific self-antigen is known.
恢复蛋白是参与脊椎动物光感受器光转导的钙结合蛋白EF手家族的成员。恢复蛋白还被鉴定为视网膜退行性疾病癌症相关性视网膜病变（CAR）中的一种自身抗原，CAR是一种副肿瘤综合征，在一些癌症患者中，免疫反应会导致光感受器退化。在本研究中，我们证明恢复蛋白在一名CAR患者的肺肿瘤中表达，但在没有相关视网膜病变的个体的相似肿瘤中不表达。通过使用针对恢复蛋白分子不同区域产生的抗恢复蛋白抗体，对CAR患者的活检组织进行蛋白质印迹分析，最初鉴定出了恢复蛋白。此外，活检组织的培养细胞表达恢复蛋白，这通过使用从细胞中提取的RNA进行逆转录-聚合酶链反应得以证明。在本研究中，还通过使用覆盖整个恢复蛋白序列的重叠七肽的固相免疫测定法确定了恢复蛋白的免疫显性区域。两个线性氨基酸片段（第64 - 70位残基，赖氨酸-丙氨酸-酪氨酸-丙氨酸-谷氨酰胺-组氨酸-缬氨酸；以及第48 - 52位残基，谷氨酰胺-苯丙氨酸-谷氨酰胺-丝氨酸-异亮氨酸）构成了主要决定簇。恢复蛋白分子的同一区域之一（第64 - 70位残基）也是唯一具有免疫致病性的，用相应肽免疫刘易斯大鼠会导致光感受器退化。这些数据表明，神经抗原恢复蛋白很可能是一些癌症患者视力丧失相关免疫事件的原因。这些数据还将CAR确立为少数几种已知特异性自身抗原的自身免疫介导疾病之一。
