Gill Sandeep K, Ishak Margaret, Rylett R Jane
Department of Physiology and Pharmacology, Medical Sciences Building, University of Western Ontario, London, Ont., Canada N6A 5C1.
J Neurosci Methods. 2005 Oct 15;148(1):26-35. doi: 10.1016/j.jneumeth.2005.03.008.
Immunohistochemical and immunofluorescence staining approaches are powerful tools for characterization of the endogenous protein expression and subcellular compartmentalization. However, several technical problems hamper identification of low-abundance nuclear proteins in archival formalin-fixed, paraffin-embedded human neural tissue. These include loss of protein antigenicity during tissue fixation and processing, and intrinsic auto-fluorescence associated with the tissue related to its fixation and the presence of lipofuscin. We evaluated several antigen retrieval methods to establish a strategy for detection of neuronal nuclear proteins in human spinal cord formalin-fixed, paraffin-embedded tissue. Thus, using immunostaining of the neuron-specific nuclear protein NeuN as the outcome measure, we found that heating tissue sections in an alkaline pH buffer unmasked protein epitopes most effectively. Moreover, staining by immunohistochemistry with diaminobenzidine tetrahydrochloride chromagen was superior to immunofluorescence labeling, likely due to the signal amplification steps included in the former approach. Auto-fluorescence in the tissue sections can be effectively reduced, but a sufficient fluorescence signal associated with specific antibody labeling could not be detected above this background for NeuN in the nucleus.
免疫组织化学和免疫荧光染色方法是表征内源性蛋白质表达和亚细胞区室化的有力工具。然而,一些技术问题阻碍了在存档的福尔马林固定、石蜡包埋的人类神经组织中鉴定低丰度核蛋白。这些问题包括组织固定和处理过程中蛋白质抗原性的丧失,以及与组织固定和脂褐素存在相关的固有自发荧光。我们评估了几种抗原修复方法,以建立一种在人类脊髓福尔马林固定、石蜡包埋组织中检测神经元核蛋白的策略。因此,以神经元特异性核蛋白NeuN的免疫染色作为结果指标,我们发现将组织切片在碱性pH缓冲液中加热能最有效地暴露蛋白质表位。此外,用四盐酸二氨基联苯胺显色剂进行免疫组织化学染色优于免疫荧光标记,这可能是由于前一种方法包含信号放大步骤。组织切片中的自发荧光可以有效降低,但在此背景之上,无法检测到与细胞核中NeuN特异性抗体标记相关的足够荧光信号。