Abstract：Objective To study the expression of SUMO-modified CCAAT enhancer binding protein α (C/EBPα) in preterm rat model of bronchopulmonary dysplasisa (BPD) induced by hyperoxia exposure and its role. Methods Eighteen preterm rats were randomly divided into an air group and a hyperoxia group (n=9 each). The model of BPD was prepared in preterm rats exposed to hyperoxia. The rats from the two groups were sacrificed on postnatal days 4, 7 and 14 respectively (3 rats at each time) and lung tissues were harvested. Periodic acid-Schiff (PAS) staining was used to observe the differentiation of rat lung tissues. Ki67 expression was detected by immunohistochemistry. Western blot was used to measure the protein expression of small ubiquitin-related modifier-1(SUMO1) and C/EBPα. A co-immunoprecipitation assay was performed to measure the protein expression of SUMO-modified C/EBPα. Results Compared with the air group, the hyperoxia group showed a decreased glycogen content in the lung tissue on postnatal day 4, and an increased content on postnatal days 7 and 14. Over the time of hyperoxia exposure, the hyperoxia group showed an increased expression of Ki67 in the lung tissue compared with the air group at all time points. Compared with the air group, the protein expression of C/EBPα increased on postnatal day 4 and decreased on postnatal days 7 and 14 in the hyperoxia group (P < 0.05). The hyperoxia group had significantly upregulated expression of SUMO1 and SUMO-modified C/EBPα compared with the air group at all time points (P < 0.05). In the hyperoxia group, the protein expression of SUMO-modified C/EBPα was positively correlated with the glycogen content (r=0.529, P < 0.05) and the expression of Ki67 (r=0.671, P < 0.05). Conclusions Hyperoxia may induce over-proliferation and differentiation disorders of alveolar epithelial cells in preterm rat model of BPD, possibly through an increased expression of SUMO-modified C/EBPα.
ZHU Yue,LU Hong-Yan,HAO Xiao-Bo et al. Dynamic expression and role of SUMO-modified C/EBPα in preterm rats with bronchopulmonary dysplasisa induced by hyperoxia exposure[J]. CJCP, 2018, 20(5): 403-409.
Kalikkot Thekkeveedu R, Guaman MC, Shivanna B. Bronchopulmonary dysplasia:A review of pathogenesis and pathophysiology[J]. Respir Med, 2017, 132:170-177.
[2]
Xue M, Li X, Chen W. Hypoxia regulates the expression and localization of CCAAT/enhancer binding protein α by hypoxia inducible factor-1α in bladder transitional carcinoma cells[J]. Mol Med Rep, 2015, 21(3):345-351.
[3]
Yang G, Hinson MD, Bordner JE, et al. Silencing hyperoxiainduced C/EBPα in neonatal mice improves lung architecture via enhanced proliferation of alveolar epithelial cells[J]. Am J Physiol Lung Cell Mol Physiol, 2011, 301(2):L187-L196.
Sato Y, Miyake K, Kaneoka H, et al. Sumoylation of CCAAT/enhancer-binding protein alpha and its functional roles in hepatocyte differentiation[J]. J Biol Chem, 2006, 281(31):21629-21639.
[6]
Yuan H, Zhang T, Liu X, et al. Sumoylation of CCAAT/enhancer-binding protein α is implicated in hematopoietic stem/progenitor cell development through regulating runx1 in zebrafish[J]. Sci Rep, 2015, 5:9011.
[7]
Chen YD, Liu JY, Lu YM, et al. Functional roles of C/EBPα and SUMO-modification in lung development[J]. Int J Mol Med, 2017, 40(4):1037-1046.
[8]
Warner BB, Stuart LA, Papes RA, et al. Functional and pathological effects of prolonged hyperoxia in neonatal mice[J]. Am J Physiol, 1998, 275(1 Pt 1):L110-L117.
[9]
Pan B, Xue X, Zhang D, et al. SOX4 arrests lung development in rats with hyperoxia-induced bronchopulmonary dysplasia by controlling EZH2 expression[J]. Int J Mol Med, 2017, 40(6):1691-1698.
[10]
Roos AB, Berg T, Barton JL, et al. Airway epithelial cell differentiation during lung organogenesis requires C/EBPα and C/EBPβ[J]. Dev Dyn, 2012, 241(5):911-923.
Torres F, González-Candia A, Montt C, et al. Melatonin reduces oxidative stress and improves vascular function in pulmonary hypertensive newborn sheep[J]. J Pineal Res, 2015, 58(3):362-373.
[13]
Jiang Y, Wang J, Tian H, et al. Increased SUMO-1 expression in response to hypoxia:Interaction with HIF-1α in hypoxic pulmonary hypertension[J]. Int J Mol Med, 2015, 36(1):271-281.
[14]
Geletu M, Balkhi MY, Peer Zada AA, et al. Target proteins of C/EBPalphap30 in AML:C/EBPalphap30 enhances sumoylation of C/EBPalphap42 via up-regulation of Ubc9[J]. Blood, 2007, 110(9):3301-3309.
[15]
Mackert JR, Qu P, Min Y, et al. Dual negative roles of C/EBPα in the expansion and pro-tumor fuctions of MDSCs[J]. Sci Rep, 2017, 7(1):14048.
[16]
Hankey W, Silver M, Sun BS, et al. Differential effects of sumoylation on the activities of CCAAT enhancer binding protein alpha (C/EBPα) p42 versus p30 may contribute in part, to aberrant C/EBPα activity in acute leukemias[J]. Hematol Rep, 2011, 3(1):e5.
[17]
Gerlach JC, Over P, Foka HG, et al. Role of transcription factor CCAAT/enhancer-binding protein alpha in human fetal liver cell types in vitro[J]. Hepatol Res, 2015, 45(8):919-932.
[18]
Xu Y, Saegusa C, Schehr A, et al. C/EBPalpha is required for pulmonary cytoprotection during hyperoxia[J]. Am J Physiol Lung Cell Mol Physiol, 2009, 297(2):L286-L298.
[19]
Lu GD, Leung CH, Yan B, et al. C/EBPalpha is up-regulated in a subset of hepatocellular carcinomas and plays a role in cell growth and proliferation[J]. Gastroenterology, 2010, 139(2):632-643.
