Differential Expression of Claudins in Retinas During Normal Development and the Angiogenesis of Oxygen- Induced Retinopathy
Total Page:16
File Type:pdf, Size:1020Kb
Retinal Cell Biology Differential Expression of Claudins in Retinas during Normal Development and the Angiogenesis of Oxygen- Induced Retinopathy Yan Luo,*,1,2 Wei Xiao,1,2 Xiaobo Zhu,1 Yani Mao,3 Xialin Liu,1 Xiaoyun Chen,1 Juan Huang,1 Shibo Tang,*,1 and Lawrence J. Rizzolo4 PURPOSE. Angiogenesis accompanies several retinal pathologies angiogenesis induced by oxygen formed a leaky barrier due to that impair the inner blood–retinal barrier. Claudins are key the mislocalization of these claudins. Studies of the mecha- structural and functional proteins of the barrier. This study nisms that regulate the intracellular distribution of claudins compared the expression of claudins during the normal angio- may lead to new therapeutic approaches for retinal vascular genesis of development with that of oxygen-induced retinop- disease. (Invest Ophthalmol Vis Sci. 2011;52:7556–7564) DOI: athy. 10.1167/iovs.11-7185 METHODS. Real-time PCR was used to monitor mRNA from postnatal day 8 (P8) to P21 in normal mice and oxygen-induced he microenvironment of the retina is separated from the retinopathy (OIR) mice. Protein expression was monitored by Tcirculation by the blood–retinal barrier. This barrier in- immunoblotting and immunofluorescence. Isolectin B4 was cludes the outer blood–retinal barrier formed by the retinal used to identify blood vessels and occludin was used to identify pigment epithelium and the inner blood–retinal barrier (iBRB) tight junctions. Neovascularization and permeability were formed by retinal vessel endothelial cells. The iBRB controls monitored using FITC–dextran and Evans blue. cellular and molecular trafficking between the blood and inter- stitium of the neural retina. Disruption of the iBRB occurs in a RESULTS. The mRNA of claudin-1, -2, -3, -4, -5, -12, -22, and -23 number of ocular fundus diseases, such as diabetic retinopa- was developmentally regulated, but only claudin-1, -2, and -5 thy1 and retinopathy of prematurity.2 were found in the tight junctions of retinal vessels. OIR in- The barrier function of the iBRB depends on the integrity of duced the formation of leaky neovascular vessels. The mRNA the tight junctions that seal the space between adjacent endo- and protein of claudin-2 and -5 were overexpressed, whereas thelial cells. This semiselective seal retards the diffusion of claudin-1 and occludin were unaffected. Despite their overex- solutes across these paracellular spaces. Tight junctions also pression, each claudin was distributed throughout the cell, divide the plasma membrane into apical and basolateral mem- especially in the neovascular tufts. Occludin was retained at brane domains and maintain cell polarity.3–5 The numerous the lateral membranes but exhibited a punctate distribution. tight junction proteins include transmembrane and scaffold CONCLUSIONS. Claudin-1, -2, and -5 are the most prominent proteins. Transmembrane proteins include claudins, junctional claudins of the inner blood–retinal barrier. The pathologic adhesion molecules, occludin, and tricellulin.6 Claudins form the tight junctional strands that are observed by electron microscopy and determine the permeability and 7–9 1 selectivity of the strands. Claudins are 20- to 27-kDa tetras- From the State Key Laboratory of Ophthalmology, Zhongshan pan proteins with a short cytoplasmic N-terminus, two extra- Ophthalmic Center, Sun Yat-sen University, Guangzhou, P.R. China; 10 3 cellular loops, and a C-terminal cytoplasmic domain. At least the Department of Ophthalmology, Guangzhou Women and Chil- 11 dren’s Medical Center, Guangzhou, P.R. China; and the 4Department of 24 family members have been identified. Each tissue ex- Surgery, Department of Ophthalmology and Visual Sciences, Yale Uni- presses its own subset of claudins, according to the physiologic 12–16 versity School of Medicine, New Haven, Connecticut. role of that tissue. In the eye, tissue-specific expression 2These authors contributed equally to the work presented here has been reported for the lens, cornea, and conjunctiva.17,18 and should therefore be regarded as equivalent authors. The expression profile and function of the claudins have Supported in part by National Natural Science Foundation of not been reported for the iBRB. This study examines the mRNA China Grants 30872819 (YL) and 81070747 (XL), Program for New and protein expression levels of claudin family members dur- Century Excellent Talents in University Grant NCET-09-0809 (YL), ing the normal formation of the iBRB and the hyperstimulated Fundamental Research Funds of State Key Laboratory Grant CX-03 retinal angiogenesis of oxygen-induced retinopathy (OIR). (YL), Science and Technology Projects in Guangdong Province Grant 2009B030801024 (YL), and Bureau of Science, Technology and Infor- With the retinas of normal development and OIR, we could mation of Guangzhou Grant 2008J1-C011 (YM). begin to address the questions of the expression and distribu- Submitted for publication January 7, 2011; revised July 9, 2011; tion of claudins during retinal angiogenesis. accepted August 11, 2011. Disclosure: Y. Luo, None; W. Xiao, None; X. Zhu, None; Y. Mao, None; X. Liu, None; X. Chen, None; J. Huang, None; S. Tang, None; METHODS L.J. Rizzolo, None *Each of the following is a corresponding author: Yan Luo, State Animals Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, P. R. China All the studies adhered to the ARVO Statement for the Use of Animals [email protected]. in Ophthalmic and Vision Research and were approved by the Ethics Shibo Tang, State Key Laboratory of Ophthalmology, Zhongshan Oph- Committee in Animal and Human Experimentation of Sun Yat-sen thalmic Center, Sun Yat-sen University, Guangzhou, 510060, P. R. University, Guangzhou, China. C57BL/6J mice were purchased from China; [email protected]. Southern Medical University, Guangzhou, China. Mouse pups and their Investigative Ophthalmology & Visual Science, September 2011, Vol. 52, No. 10 7556 Copyright 2011 The Association for Research in Vision and Ophthalmology, Inc. Downloaded from jov.arvojournals.org on 09/29/2021 IOVS, September 2011, Vol. 52, No. 10 Claudins in Retinal Angiogenesis 7557 TABLE 1. Real-Time PCR Primers Used in This Study Gene Accession No. Primers Product Size (bp) 18S XR034450 5Ј-TTCCGATAACGAACGAGACTCT-3Ј 99 RNA 5Ј-TGGCTGAACGCCACTTGTC-3Ј Cldn-1 NM016674 5Ј-TCTACGAGGGACTGTGGATG-3Ј 84 5Ј-TCAGATTCAGCTAGGAGTCG-3Ј Cldn-2 NM016675 5Ј-GGCTGTTAGGCTCATCCAT-3Ј 66 5Ј-TGGCACCAACATAGGAACTC-3Ј Cldn-3 NM009902 5Ј-AAGCCGAATGGACAAAGAA-3Ј 72 5Ј-CTGGCAAGTAGCTGCAGTG-3Ј Cldn-4 NM009903 5Ј-CGCTACTCTTGCCATTACG-3Ј 71 5Ј-ACTCAGCACACCATGACTTG-3Ј Cldn-5 NM013805 5Ј-GTGGAACGCTCAGATTTCAT-3Ј 97 5Ј-TGGACATTAAGGCAGCATCT-3Ј Cldn-6 NM018777 5Ј-CATTACATGGCCTGCTATTC-3Ј 75 5Ј-CACATAATTCTTGGTGGGATATT-3Ј Cldn-7 NM016887 5Ј-AGGGTCTGCTCTGGTCCTT-3Ј 76 5Ј-GTACGCAGCTTTGCTTTCA-3Ј Cldn-8 NM018778 5Ј-GCCGGCATCATCTTCTTCAT-3Ј 100 5Ј-CATCCACCAGTGGGTTGTAG-3Ј Cldn-9 NM020293 5Ј-GTCACACTTTGAGCGTCCC-3Ј 82 5Ј-CCTCTTATCCAGTCCCGAAG-3Ј Cldn-10 NM021386 5Ј-CCCAGAATGGGCTACACATA-3Ј 74 5Ј-CCTTCTCCGCCTTGATACTT-3Ј Cldn-11 NM021386 5Ј-TCTTGGTTCCTGTATGTGCC-3Ј 63 5Ј-CGTACAGCGAGTAGCCAAAG-3Ј Cldn-12 NM022890 5Ј-GTCCTCTCCTTTCTGGCAAC-3Ј 105 5Ј-ATGTCGATTTCAATGGCAGA-3Ј Cldn-13 NM020504 5Ј-TAGTGTTGGCCTTCTTGAGC-3Ј 83 5Ј-AGCCAAGCAATGGGTTAAAG-3Ј Cldn-14 NM019500 5Ј-GCTCCTAGGCTTCCTGCTTA-3Ј 169 5Ј-CTGGTAGATGCCTGTGCTGT-3Ј Cldn-15 NM021719 5Ј-CAGCTTCGGTAAATATGCCA-3Ј 76 5Ј-CAGTGGGACAAGAAATGGTG-3Ј Cldn-16 NM053241 5Ј-GCCATATTCTCCACTGGGTT-3Ј 70 5Ј-AGTCATCAGCGTTCACCATC-3Ј Cldn-17 NM181490 5Ј-TCGTTCTGATTCCAGTGTCC-3Ј 95 5Ј-TCCTCCAAGTTCTCGCTTCT-3Ј Cldn-18 NM019815 5Ј-GACCGTTCAGACCAGGTACA-3Ј 96 5Ј-GCGATGCACATCATCACTC-3Ј Cldn-19 NM153105 5Ј-ACCAGAATGAGGACCAGGAT-3Ј 75 5Ј-TCCTTCAGCAAATACGTTGG-3Ј Cldn-20* XM888581 5Ј-CAGCTCCTTGCTTTCATCCTG-3Ј 354 5Ј-CAGACTCCTCCAGCAAAGGAA-3Ј Cldn-20† XM888581 5Ј-TCCAGCTCCTTGCTTTCA-3Ј 105 5Ј-ATGTTGGGTCCTGCGTAT-3Ј Cldn-22 NM029383 5Ј-GCTCCTGCAGCCTCGAGTCACTATG-3Ј 81 5Ј-TGGATTGGCTTGCTTCAGCTCCA-3Ј Cldn-23 NM027998 5Ј-ACAGGGACACCAGCAAGCTCAA-3Ј 178 5Ј-AGGTCAGAGTCACAGGGCAACGAA-3Ј Occludin NM008756 5Ј-AGACCCAAGAGCAGCCAAAG-3Ј 61 5Ј-GGAAGCGATGAAGCAGAAGG-3Ј All primers were designed using commercial software (Primer Premier 5.0; PREMIER Biosoft Inter- national). * Primers were used for RT-PCR. † Primers were used for real-time PCR. mothers were housed in special pathogen-free conditions at the animal Aldrich, St. Louis, MO). DNase I–treated RNA (1 g) was then con- laboratory center of Zhongshan Ophthalmic Center, Guangzhou, verted to cDNA using reverse transcriptase (Takara, Siga, Japan). cDNA China. The number of pups present in each litter was about the same samples were aliquoted and stored at Ϫ80°C. (n ϭ 8–12); 23 litters were analyzed in this study. RNA Isolation and cDNA Preparation Nonquantitative PCR and Quantitative Real-Time PCR After mice were anesthetized by an intraperitoneal (IP) injection of 10% chloral hydrate (2.5 mL/kg), retinas of postnatal day 8 (P8), P11, Primers for claudins, occludin, and 18S rRNA (Table 1) were designed P13, P15, P18, and P21 mice, together with kidney and brain of using commercial software (Primer Premier 5.0; PREMIER Biosoft In- 6-week-old mice, were collected. Total RNA was extracted using a ternational, Palo Alto, CA). Specificity of the primer sequences was commercial reagent (TRIzol; Invitrogen, Carlsbad, CA) according to examined using the National Center for Biotechnology Information the manufacturer’s instructions. Potential contamination by genomic Basic Local Alignment Search Tool module.