Ding XiaoDong, Chen YuanWen, Han LianShu, Qiu WenJuan, Gu XueFan, Zhang HuiWen
Department of Pediatric Endocrinologic, Genetic and Metabolic Diseases, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, PR China; Department of Gastroenterology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, PR China.
Department of Gastroenterology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, PR China.
Biochem Biophys Res Commun. 2015 May 15;460(4):915-22. doi: 10.1016/j.bbrc.2015.03.127. Epub 2015 Mar 31.
Apoptosis Related Protein 3 (APR3) is an important protein which is involved in retinoic acid-induced apoptosis, osteoblast differentiation and cervical squamous cell carcinoma progression. Although it was predicted to be a trans-membrane protein, its cellular localization is not clear. In this study, we analyzed APR3 with bioinformatic tools and found that APR3 contains a potential signal peptide, a transmembrane region and 3 N-glycosylation sites, all of which are characteristics of lysosomal proteins. Western blot with isolated lysosomes demonstrated that APR3 was mainly present in lysosomes, specially in the lysosomal membrane fraction, but not in endoplasmic reticulum. Concomitantly, double immunofluorescence confirmed that APR3 co-localized with lysosomal membrane protein, LAMP1, as well as lysosomal specific marker, Lyso-Tracker Red. Moreover, we showed that APR3 was highly expressed in the lung, liver, spleen, kidney and adipose tissue, but expressed at the low level in the heart, pancreas, stomach and intestine. Interestingly, APR3 expression was elevated in multiple hepatocellular carcinoma cell lines comparing to normal liver cells. Collectively, our results proved that APR3 is a novel lysosomal membrane protein and shed light on its possible functions.
凋亡相关蛋白3（APR3）是一种重要的蛋白质，它参与视黄酸诱导的凋亡、成骨细胞分化和宫颈鳞状细胞癌进展。尽管它被预测为一种跨膜蛋白，但其细胞定位尚不清楚。在本研究中，我们使用生物信息学工具分析了APR3，发现APR3含有一个潜在的信号肽、一个跨膜区域和3个N-糖基化位点，所有这些都是溶酶体蛋白的特征。对分离的溶酶体进行蛋白质免疫印迹分析表明，APR3主要存在于溶酶体中，特别是在溶酶体膜部分，而在内质网中不存在。同时，双重免疫荧光证实APR3与溶酶体膜蛋白LAMP1以及溶酶体特异性标记物Lyso-Tracker Red共定位。此外，我们发现APR3在肺、肝、脾、肾和脂肪组织中高表达，但在心脏、胰腺、胃和肠道中低表达。有趣的是，与正常肝细胞相比，APR3在多种肝癌细胞系中的表达升高。总的来说，我们的结果证明APR3是一种新型的溶酶体膜蛋白，并揭示了其可能的功能。
