Abstract
Phagocytic clearance of the spent photoreceptor outer segments (OS) by RPE cells is regulated by circadian rhythm cycle and is essential for photoreceptor integrity and function. Mertk regulates RPE phagocytosis and a deficiency in Mertk causes photoreceptor degeneration and visual loss. This study aimed to investigate Mertk regulation of the microRNAs (miRNA), potentially regulating expression of their target genes, which affect phagocytosis. The differentially expressed miRNAs were identified using miRCURYTM microRNA Arrays from total RNA isolated at 0900 h and 1900 h from the mechanically dissociated RPE sheets of the WT and Mertk −/− mice, which were housed in a 12-h light-dark cycle with the lighting onset at 0700 h (7:00am). Validation of the differentially expressed miRNAs and assessment of the putative miRNA target gene expression were performed by real-time PCR. Among the differentially expressed miRNAs in the Mertk −/− RPE, seven miRNAs were up-regulated and 13 were down-regulated in the morning groups. Similarly, 24 miRNAs were found to be up-regulated and 13 were down-regulated in the evening groups. To search for those that may participate in regulating expression of cytoskeletal proteins, we examined the predicted target genes that might participate in phagocytosis were examined by real-time PCR. Of nine potential altered targets, four deregulated genes were myosin subunits. Notably, multiple members of the 21 up-regulated miRNAs can theoretically recognize these down-regulated mRNAs, particularly MyH14 and Myl3. This study shows that loss of Mertk alters miRNA expression, which in turn affects expression of the downstream target genes, potentially affecting phagocytosis.
Similar content being viewed by others
References
Bartel DP (2004) MicroRNAs: genomics, biogenesis, mechanism, and function. Cell 116:281–297
Bok D, Hall MO (1971) The role of the pigment epithelium in the etiology of inherited retinal dystrophy in the rat. J Cell Biol 49:664–682
D'Cruz PM, Yasumura D, Weir J, Matthes MT, Abderrahim H et al (2000) Mutation of the receptor tyrosine kinase gene Mertk in the retinal dystrophic RCS rat. Hum Mol Genet 9:645–651
Duncan JL, LaVail MM, Yasumura D, Matthes MT, Yang H et al (2003) An RCS-like retinal dystrophy phenotype in mer knockout mice. Invest Ophthalmol Vis Sci 44:826–838
Edwards RB, Szamier RB (1977) Defective phagocytosis of isolated rod outer segments by RCS rat retinal pigment epithelium in culture. Science 197:1001–1003
Gal A, Li Y, Thompson DA, Weir J, Orth U et al (2000) Mutations in MERTK, the human orthologue of the RCS rat retinal dystrophy gene, cause retinitis pigmentosa. Nat Genet 26:270–271
Gibbs D, Kitamoto J, Williams DS (2003) Abnormal phagocytosis by retinal pigmented epithelium that lacks myosin VIIa, the Usher syndrome 1B protein. Proc Natl Acad Sci U S A 100:6481–6486
He L, Hannon GJ (2004) MicroRNAs: small RNAs with a big role in gene regulation. Nat Rev Genet 5:522–531
Huang KM, Dentchev T, Stambolian D (2008) MiRNA expression in the eye. Mamm Genome 19:510–516
Karali M, Peluso I, Marigo V, Banfi S (2007) Identification and characterization of microRNAs expressed in the mouse eye. Invest Ophthalmol Vis Sci 48:509–515
LaVail MM (1973) Kinetics of rod outer segment renewal in the developing mouse retina. J Cell Biol 58:650–661
LaVail MM (1976) Rod outer segment disk shedding in rat retina: relationship to cyclic lighting. Science 194:1071–1074
LaVail MM (1980) Circadian nature of rod outer segment disc shedding in the rat. Invest Ophthalmol Vis Sci 19:407–411
Loscher CJ, Hokamp K, Kenna PF, Ivens AC, Humphries P et al (2007) Altered retinal microRNA expression profile in a mouse model of retinitis pigmentosa. Genome Biol 8:R248
Lu Q, Gore M, Zhang Q, Camenisch T, Boast S et al (1999) Tyro-3 family receptors are essential regulators of mammalian spermatogenesis. Nature 398:723–728
Lu H, Lu Q, Gaddipati S, Kasetti RB, Wang W et al (2014) IKK2 inhibition attenuates laser-induced choroidal neovascularization. PLoS One 9:e87530
McHenry CL, Liu Y, Feng W, Nair AR, Feathers KL et al (2004) MERTK arginine-844-cysteine in a patient with severe rod-cone dystrophy: loss of mutant protein function in transfected cells. Invest Ophthalmol Vis Sci 45:1456–1463
Nandrot EF, Finnemann SC (2006) Altered rhythm of photoreceptor outer segment phagocytosis in beta5 integrin knockout mice. Adv Exp Med Biol 572:119–123
Nandrot E, Dufour EM, Provost AC, Pequignot MO, Bonnel S et al (2000) Homozygous deletion in the coding sequence of the c-mer gene in RCS rats unravels general mechanisms of physiological cell adhesion and apoptosis. Neurobiol Dis 7:586–599
Nandrot EF, Kim Y, Brodie SE, Huang X, Sheppard D et al (2004) Loss of synchronized retinal phagocytosis and age-related blindness in mice lacking alphavbeta5 integrin. J Exp Med 200:1539–1545
Nandrot EF, Anand M, Sircar M, Finnemann SC (2006) Novel role for alphavbeta5-integrin in retinal adhesion and its diurnal peak. Am J Physiol Cell Physiol 290:C1256–C1262
Pegoraro M, Tauber E (2008) The role of microRNAs (miRNA) in circadian rhythmicity. J Genet 87:505–511
Prasad D, Rothlin CV, Burrola P, Burstyn-Cohen T, Lu Q et al (2006) TAM receptor function in the retinal pigment epithelium. Mol Cell Neurosci 33:96–108
Robosky LC, Wade K, Woolson D, Baker JD, Manning ML et al (2008) Quantitative evaluation of sebum lipid components with nuclear magnetic resonance. J Lipid Res 49:686–692
Ryan DG, Oliveira-Fernandes M, Lavker RM (2006) MicroRNAs of the mammalian eye display distinct and overlapping tissue specificity. Mol Vis 12:1175–1184
Smith RJ, Berlin CI, Hejtmancik JF, Keats BJ, Kimberling WJ et al (1994) Clinical diagnosis of the Usher syndromes. Usher Syndrome Consortium. Am J Med Genet 50:32–38
Strick DJ, Feng W, Vollrath D (2009) Mertk drives myosin II redistribution during retinal pigment epithelial phagocytosis. Invest Ophthalmol Vis Sci 50:2427–2435
Thompson DA, McHenry CL, Li Y, Richards JE, Othman MI et al (2002) Retinal dystrophy due to paternal isodisomy for chromosome 1 or chromosome 2, with homoallelism for mutations in RPE65 or MERTK, respectively. Am J Hum Genet 70:224–229
Tschernutter M, Jenkins SA, Waseem NH, Saihan Z, Holder GE et al (2006) Clinical characterisation of a family with retinal dystrophy caused by mutation in the Mertk gene. Br J Ophthalmol 90:718–723
Vicente-Manzanares M, Ma X, Adelstein RS, Horwitz AR (2009) Non-muscle myosin II takes centre stage in cell adhesion and migration. Nat Rev Mol Cell Biol 10:778–790
Weil D, Blanchard S, Kaplan J, Guilford P, Gibson F et al (1995) Defective myosin VIIA gene responsible for Usher syndrome type 1B. Nature 374:60–61
Xin Y, Lu Q, Li Q (2010) 14-3-3sigma controls corneal epithelial cell proliferation and differentiation through the Notch signaling pathway. Biochem Biophys Res Commun 392:593–598
Xu S, Witmer PD, Lumayag S, Kovacs B, Valle D (2007) MicroRNA (miRNA) transcriptome of mouse retina and identification of a sensory organ-specific miRNA cluster. J Biol Chem 282:25053–25066
Young RW (1967) The renewal of photoreceptor cell outer segments. J Cell Biol 33:61–72
Young RW, Bok D (1969) Participation of the retinal pigment epithelium in the rod outer segment renewal process. J Cell Biol 42:392–403
Acknowledgments
This paper was supported by NIH grants R01EY018830 and Research to Prevent Blindness.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Tang, Y., Lu, Q., Wei, Y. et al. Mertk deficiency alters expression of micrornas in the retinal pigment epithelium cells. Metab Brain Dis 30, 943–950 (2015). https://doi.org/10.1007/s11011-015-9653-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11011-015-9653-5