Roudkenar Mehryar Habibi, Halabian Raheleh, Roushandeh Amaneh Mohammadi, Nourani Mohammad Reza, Masroori Nasser, Ebrahimi Majid, Nikogoftar Mahin, Rouhbakhsh Mehdi, Bahmani Parisa, Najafabadi Ali Jahanian, Shokrgozar Mohammad Ali
Research Center, Iranian Blood Transfusion Organization, Tehran, Iran.
Exp Cell Res. 2009 Nov 1;315(18):3140-51. doi: 10.1016/j.yexcr.2009.08.019. Epub 2009 Sep 2.
Environmental temperature variations are the most common stresses experienced by a wide range of organisms. Lipocalin 2 (Lcn2/NGAL) is expressed in various normal and pathologic conditions. However, its precise functions have not been fully determined. Here we report the induction of Lcn2 by thermal stresses in vivo, and its role following exposure to cold and heat stresses in vitro. Induction of Lcn2 in liver, heart and kidney was detected by RT-PCR, Western blot and immunohistochemistry following exposure of mice to heat and cold stresses. When CHO and HEK293T cells overexpressing NGAL were exposed to cold stress, cell proliferation was higher compared to controls. Down-regulatrion of NGAL by siRNA in A549 cells resulted in less proliferation when exposed to cold stress compared to control cells. The number of apoptotic cells and expression of pro-apoptotic proteins were lower in the NGAL overexpressing CHO and HEK293T cells, but were higher in the siRNA-transfected A549 cells compared to controls, indicating that NGAL protects cells against cold stress. Following exposure of the cells to heat stress, ectopic expression of NGAL protected cells while addition of exogenous recombinant NGAL to the cell culture medium exacerbated the toxicity of heat stress specially when there was low or no endogenous expression of NGAL. It had a dual effect on apoptosis following heat stress. NGAL also increased the expression of HO-1. Lcn2/NGAL may have the potential to improve cell proliferation and preservation particularly to prevent cold ischemia injury of transplanted organs or for treatment of some cancers by hyperthermia.
环境温度变化是多种生物体所经历的最常见应激。脂质运载蛋白2（Lcn2/NGAL）在各种正常和病理条件下均有表达。然而，其确切功能尚未完全确定。在此我们报告了体内热应激对Lcn2的诱导作用，以及体外暴露于冷应激和热应激后其发挥的作用。在小鼠暴露于热应激和冷应激后，通过RT-PCR、蛋白质免疫印迹和免疫组织化学检测肝脏、心脏和肾脏中Lcn2的诱导情况。当过表达NGAL的CHO和HEK293T细胞暴露于冷应激时，与对照相比细胞增殖更高。在A549细胞中，通过小干扰RNA（siRNA）下调NGAL后，与对照细胞相比，暴露于冷应激时细胞增殖减少。过表达NGAL的CHO和HEK293T细胞中凋亡细胞数量和促凋亡蛋白表达较低，但与对照相比，在转染siRNA的A549细胞中更高，这表明NGAL可保护细胞免受冷应激。细胞暴露于热应激后，NGAL的异位表达可保护细胞，而向细胞培养基中添加外源性重组NGAL会加剧热应激的毒性，特别是当NGAL的内源性表达较低或无内源性表达时。它对热应激后的凋亡有双重作用。NGAL还增加了血红素加氧酶-1（HO-1）的表达。Lcn2/NGAL可能有潜力改善细胞增殖和存活，特别是预防移植器官的冷缺血损伤或通过热疗治疗某些癌症。
