HaloTag 技术在α-突触核蛋白质的细胞影像与定量分析中的应用

目的：探讨 HaloTag 技术用于α-突触核蛋白质（α-synuclein,SNCA）在细胞内荧光成像及半定量分析的方法及其应用。方法采用重组克隆技术构建 pHalo-SNCA 质粒,将其转染至 HEK293人胚肾细胞中,经 Western blotting 鉴定 Halo-SNCA 融合蛋白质的表达;通过激光共聚焦显微镜观察 Halo-SNCA 在细胞内的定位与分布;通过蛋白酶催化的解偶联反应的荧光强度测定细胞内 Halo-SNCA 的荧光强度进行目的蛋白质的间接定量分析。结果本研究成功构建了 Halo-SNCA 真核表达质粒,能够在转染的真核细胞中高效表达目的融合蛋白质,该融合蛋白质结合特定的荧光配基后,可通过激光共聚焦显微成像分析 Halo-SNCA 在细胞中的动态水平与分布状况。此外,经水解释放的荧光配基可用于表达融合蛋白质在细胞中较为精确的相对定量分析。结论HaloTag 技术能够用于 SNCA 在细胞内成像和定量分析,同时可以作为细胞生物学和生物化学分析的可关联检测指标。对于SNCA 的生理功能以及在神经系统病变中的作用等相关研究,HaloTag 具有令人瞩目的潜在应用前景。     

MDA-7/IL-24-HT7融合蛋白的制备及其对肿瘤细胞凋亡的诱导作用

目的：构建MDA-7/IL-24-HT7原核及真核表达质粒,制备MDA-7/IL-24-HT7融合蛋白,研究该融合蛋白在肿瘤细胞内的定位及其对肿瘤细胞致凋亡作用。方法：PCR扩增MDA-7/IL-24基因,插入含有HaloTag (HT7)标签的载体中,构建MDA-7/IL-24-HT7原核及真核表达质粒;MDA-7/IL-24-HT7融合蛋白经IPTG诱导表达后纯化。利用带有荧光标记的HT7配基观察MDA-7/IL-24-HT7在肿瘤细胞内的定位。MTT法及AnnexinV-PI染色法检测MDA-7/IL-24-HT7对肿瘤细胞生长和凋亡的影响。结果：成功构建了表达MDA-7/IL-24-HT7融合蛋白的原核及真核表达质粒,MDA-7/IL-24-HT7融合蛋白主要存在于E.coli BL21的包涵体内。MDA-7/IL-24-HT7融合蛋白定位于肿瘤细胞的内质网上。MDA-7/IL-24-HT7融合蛋白可抑制肿瘤细胞的生长,1 mg/ml MDA-7/IL-24-HT7 融合蛋白作用大肠癌HCT116细胞、肝癌SMMC7721细胞96 h后,细胞凋亡率分别为（34.7±1.3）% 和（22.1±0.9）%,显著高于未处理的肿瘤细胞（P<0.01）。结论：带有HaloTag标签的MDA-7/IL-24-HT7融合蛋白可抑制肿瘤细胞增殖和诱导肿瘤细胞凋亡。     

In silico identification and experimental validation of cellular uptake and intracellular labeling by a new cell penetrating peptide derived from CDN1

Bioactive therapeutic molecules are generally impermeable to the cell membrane, hindering their utility and efficacy. A group of peptides called cell-penetrating peptides (CPPs) were found to have the capability of transporting different types of cargo molecules across the cell membrane. Here, we identified a short peptide named P2, which has a higher proportion of basic residues than the CDN1 (cyclin-dependent kinase inhibitor 1) protein it is derived from, and we used bioinformatic analysis and experimental validation to confirm the penetration property of peptide P2. We found that peptide P2 can efficiently enter different cell lines in a concentration-dependent manner. The endocytosis pathway, especially receptor-related endocytosis, may be involved in the process of P2 penetration. Our data also showed that peptide P2 is safe in cultured cell lines and red blood cells. Lastly, peptide P2 can efficiently deliver self-labeling protein HaloTag into cells for imaging. Our study illustrates that peptide P2 is a promising imaging agent delivery vehicle for future applications.