Department of Biology, Università di Padova , 35121 Padova, Italy.
Dipartimento di Farmacia-DIFAR, Università di Genova , 16132 Genoa, Italy.
J Proteome Res. 2018 Feb 2;17(2):918-925. doi: 10.1021/acs.jproteome.7b00741. Epub 2018 Jan 18.
The retinal rod outer segment (OS) is a stack of disks surrounded by the plasma membrane, housing proteins related to phototransduction, as well as mitochondrial proteins involved in oxidative phosphorylation (OxPhos). This prompted us to compare the proteome of bovine OS disks and mitochondria to assess the significant top gene signatures of each sample. The two proteomes, obtained by LTQ-Orbitrap Velos mass spectrometry, were compared by statistical analyses. In total, 4139 proteins were identified, 2045 of which overlapping in the two sets. Nonhierarchical Spearman's correlogram revealed that the groups were clearly discriminated. Partial least square discriminant plus support vector machine analysis identified the major discriminative proteins, implied in phototransduction and lipid metabolism, respectively. Gene Ontology analysis identified top gene signatures of the disk proteome, enriched in vesiculation, glycolysis, and OxPhos proteins. The tricarboxylic acid cycle and the electron transport proteins were similarly enriched in the two samples, but the latter was up regulated in disks. Data suggest that the mitochondrial OxPhos proteins may represent a true OS proteome component, outside the mitochondrion. This knowledge may help the scientific community in the further studies of retinal physiology and pathology.
视网膜杆状细胞外节（OS）是由质膜包围的堆叠盘，其中包含与光转导相关的蛋白质，以及参与氧化磷酸化（OxPhos）的线粒体蛋白质。这促使我们比较牛 OS 盘和线粒体的蛋白质组，以评估每个样本的重要顶级基因特征。通过 LTQ-Orbitrap Velos 质谱法获得的这两个蛋白质组通过统计分析进行了比较。总共鉴定出 4139 种蛋白质，其中 2045 种在两组中重叠。非层次 Spearman 相关图显示，这些组被清楚地区分。偏最小二乘判别加支持向量机分析确定了主要的判别蛋白，分别涉及光转导和脂代谢。基因本体分析确定了盘状蛋白质组的顶级基因特征，富含小泡形成、糖酵解和 OxPhos 蛋白。三羧酸循环和电子传递蛋白在这两个样本中也有类似的富集，但后者在盘状细胞中上调。数据表明，线粒体 OxPhos 蛋白可能代表真正的 OS 蛋白质组成分，位于线粒体之外。这一知识可能有助于科学界进一步研究视网膜的生理学和病理学。
