Cross‑Talks Between Micrornas and Mrnas in Pancreatic Tissues of Streptozotocin‑Induced Type 1 Diabetic Mice
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BIOMEDICAL REPORTS 3: 333-342, 2015 Cross‑talks between microRNAs and mRNAs in pancreatic tissues of streptozotocin‑induced type 1 diabetic mice CAIMING TIAN1,2*, XIAOXI OUYANG3*, QING LV1,4, YAOU ZHANG2 and WEIDONG XIE2 1Department of Chemistry, Tsinghua University, Beijing 100084; 2Shenzhen Key Laboratory of Health Science and Technology, Division of Life Science and Health, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong 518055; 3Department of Health Inspection and Quarantine, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong 510080; 4School of Life Sciences, Tsinghua University, Beijing 100084, P.R. China Received December 30, 2014; Accepted February 2, 2015 DOI: 10.3892/br.2015.426 Abstract. Network cross-talks between microRNAs (miRNAs) Introduction and mRNAs may be useful to elucidate the pathological mechanisms of pancreatic islet cells in diabetic individuals. Diabetes mellitus is a complex metabolic disease demon- The aim of the present study was to investigate the cross-talks strating impaired islet function (1,2). Destruction of β-cells between miRNAs and mRNAs in pancreatic tissues of or the failure of these insulin-secreting cells to compensate streptozotocin-induced diabetic mice through microarray and for increased metabolic demand may account for the develop- bioinformatic methods. Based on the miRNA microarray, ment of diabetes. Apoptosis, oxidative stress, mitochondrial 64 upregulated and 72 downregulated miRNAs were observed dysfunction and endoplasmic reticulum (ER) stress responses, in pancreatic tissues in diabetic mice compared to the normal including c-Jun N-terminal kinase (JNK) activation, have been controls. Based on the mRNA microarrray, 507 upregulated suggested as mechanisms for the changes of pancreatic β-cells mRNAs and 570 downregulated mRNAs were identified in in type 2 diabetes mellitus (T2DM) (3). T1DM is the result of pancreatic tissues in diabetic mice compared to the normal autoimmune destruction of pancreatic β cells (4). However, the controls. Notably, there were 246 binding points between mechanisms involved in islet dysfunction remain unclear. upregulated miRNA and downregulated mRNAs; simultane- microRNAs (miRNAs) play a key role in regulating islet ously, there were 583 binding points between downregulated function (5). Repression of mRNAs by miRNAs is an impor- miRNA and upregulated mRNAs. These changed mRNA may tant mechanism for regulation of expression during cell fate potentially involve the following signaling pathways: Insulin specification, apoptosis and metabolism (6). In the previous secretion, pancreatic secretion, mammalian target of rapamycin study, miRNA-mRNA interactions were investigated in the signaling pathway, forkhead box O signaling pathway and pancreatic islets of spontaneously diabetic Goto-Kakizaki phosphatidylinositol 3-kinase-protein kinase B signaling. The rats (7) and the human pluripotent stem cells based in vitro fluctuating effects of miRNAs and matched mRNAs indicated model of pancreatic differentiation (8). A number of key pairs that miRNAs may have wide cross-talks with mRNAs in of miRNA‑mRNA were proposed to have significant roles in pancreatic tissues of type 1 diabetic mice. The cross-talks may the pathogenesis of T2DM or islet development. However, few play important roles in contributing to impaired islet functions studies have reported the miRNA-mRNA cross-talk in T1DM. and the development of diabetes. However, further functional In the present study, the cross-talks between miRNAs and validation should be conducted in the future. mRNAs in the streptozotocin (STZ)-induced T1DM mice were investigated. Materials and methods Establishment of T1DM mouse model. Male National Institutes Correspondence to: Dr Weidong Xie, Shenzhen Key Laboratory of of Health (NIH) mice (age, 4 weeks) were purchased from Health Science and Technology, Division of Life Science and Health, the Guangdong Medical Laboratory Animal Center (Foshan, Graduate School at Shenzhen, Tsinghua University, L402E, Tsinghua China). The animals were maintained in an environmentally Campus, University Town of Xili, Shenzhen, Guangdong 518055, P. R. Ch i na controlled breeding room (temperature, 20±2˚C; humidity, E-mail: [email protected] 60±5%, dark/light cycle, 12 h). The mice were fed with stan- dard laboratory chow and water ad libitum. The study was * Contributed equally performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the Key words: diabetes, microRNA, microarray, network, islet cells Institutional Animal Care and Use Committee of Tsinghua University (Beijing, China). The protocol was approved by the 334 TIAN et al: INTERACTION BETWEEN microRNAs AND mRNAs IN DIABETIC MICE Animal Welfare and Ethics Committee of Tsinghua University. probe level (*_norm_RMA.pair) and gene level (*_RMA. Male NIH mice that were fasted for 24 h (weight, 18±2 g) were calls) files were generated following normalization. All the used to induce the diabetic model by the intrainperitoneal gene level files were imported into the Agilent GeneSpring injection of 100 mg/kg STZ (Sigma-Aldrich, St. Louis, MO, GX software (version 11.5.1) for further analysis. Genes that USA). STZ was freshly prepared in 0.1 M pre-cold citric acid were ≥2 out of 2 samples have values greater than or equal buffer (pH 4.5). One week after the injection of STZ, diabetic to the lower cut-off: 100.0 (‘All Targets Value’) were chosen animal models with fasting blood glucose of >11.1 mmol/l were for data analysis. Differentially expressed genes were identi- selected for further trials. Four weeks after STZ induction, the fied through fold‑change filtering. Pathway analysis and gene animals were sacrificed by cervical dislocation; pancreatic ontology (GO) analysis were applied to determine the roles of tissues were removed for further miRNA or RNA extractions. these differentially expressed genes played in these biological STZ-untreated mice served as the normal controls. pathways or GO terms. Finally, hierarchical clustering was performed to show distinguishable gene expression profiling miRNA microarray analysis. The miRNA chip assay was among samples. conducted by the method of Exiqon miRNA array [The 7th generation of miRCURY™ LNA array (v.18.0), KangChen miRNA‑mRNA cross‑talk analysis. Reverse expressions of Bio-tech Inc., Shanghai, China]. Three different whole miRNA and mRNA were selected (upregulation of miRNAs pancreatic tissues were freshly collected from three different by >2 fold and downregulation of mRNAs by <50%; or down- diabetic mice. The three diabetic or normal mice had similar regulation of miRNAs by <50% and upregulation of mRNAs blood glucose and body weights. Three equal volumes by >50%) for miRNA-mRNA target prediction. Three (~0.33 ml) of different homogenates from whole pancreatic different databases were used for miRNA target predictions: tissue of each mouse were mixed and subjected to miRNA miRanda (www.microrna.org/microrna/getDownloads.do), and mRNA extracts. Total RNA was harvested using TRIzol miRBase (http://www.mirbase.org/) and TargetScan (www. (Invitrogen Life Technologies, Carlsbad, CA, USA) and the targetscan.org/mmu_60/), and only those targets predicted by miRNeasy mini kit (Qiagen, Hilden, Germany) according to at least two databases were selected. Furthermore, based on the manufacturer's instructions. Subsequent to having passed the bioinformatics prediction, only miRNA target gene pairs RNA quantity measurement using the NanoDrop 1000, the with such opposing expression patterns were selected. Figures samples were labeled using the miRCURY™ Hy3™/Hy5™ of miRNA-mRNA interactions were drawn by the cytoscape Power labeling kit and hybridized on the miRCURY™ LNA software (9). Selected mRNA was subjected to further hier- array (v.18.0). Following the washing steps, the slides were archical clustering analysis, pathway analysis (http://www. scanned using the Axon GenePix 4000B microarray scanner genome.jp/kegg/pathway.html) and GO analysis. (Molecular Devices Corp., Sunnyvale, CA, USA). Scanned images were imported into the GenePix Pro 6.0 software Results (Axon Instruments, Molecular Devices Corp.) for grid align- ment and data extraction. Replicated miRNAs were averaged miRNA microarray analysis. According to the miRNA chip and miRNAs with intensities ≥30 in all the samples were report, 64 miRNAs showed >2-fold increase in pancreatic chosen for calculating the normalization factor. Expressed data tissues of diabetic mice compared to the normal controls were normalized using the median normalization. Following (Table I). However, 72 miRNAs showed ≥50% decrease in normalization, differentially expressed miRNAs were identi- pancreatic tissues of diabetic mice compared to the normal fied through fold change filtering. controls (Table II). However, functions of the majority of miRNAs remained unclear. mRNA microarray analysis. Following the miRNA micro- array analysis, collected total RNAs were also used to conduct mRNA microarray analysis. According to the gene chip report, the mRNA chip assay. The mRNA chip assay was conducted 507 mRNAs were upregulated by >2-fold while 570 mRNAs by the method of NimbleGen Mouse Gene Expression were downregulated by ≥50% (available upon request). Microarrays (KangChen Bio-tech Inc.). Total RNA from Among the upregulated mRNAs, certain genes from viral each sample was quantified by the NanoDrop ND‑1000 and myocarditis, tight junction, pentose and glucuronate