Purpose. To determine whether β-amyloid (Aβ) deposition affects the structure and function of the retina of the APPswe/PS1ΔE9 transgenic (tg) mouse model of Alzheimer’s disease. methods. Retinas from 12- to 19-month old APPswe/PS1ΔE9 tg and age-matched non-transgenic (ntg) littermates were single or double stained with thioflavine-S and antibodies against Aβ, glial fibrilar acidic protein (GFAP), microglial marker F4/80, choline acetyltransferase (ChAT), and syntaxin 1. Quantification of thioflavine-S positive plaques and retinal layer thickness was analyzed semi-quantitatively, whereas microglial cell size and levels of F4/80 immunoreactivity were evaluated using a densitometry program. Scotopic electroretinogram (ERG) recording was used to investigate retinal physiology in these mice. results. Thioflavine-S positive plaques appeared at 12 months in the retinas of APPswe/PS1ΔE9 tg mice with the majority of plaques in the outer and inner plexiform layers. Plaques were embedded in the inner plexiform layer strata displaying syntaxin 1 and ChAT. The number and size of the plaques in the retina increased with age. Plaques appeared earlier and in greater numbers in females than in male tg littermate mice. Microglial activity was significantly increased in the retinas of APPswe/PS1ΔE9 tg mice. Although we did not detect neuronal degeneration in the retina, ERG recordings revealed a significant reduction in the amplitudes of a- and b-waves in aged APPswe/PS1ΔE9 tg compared to ntg littermates. conclusions. The present findings suggest that Aβ deposition disrupts retinal structure and may contribute to the visual deficits seen in aged APPswe/PS1ΔE9 tg mice. Whether Aβ is involved in other forms of age-related retinal dysfunction is unclear.

The microRNA-183/96/182cluster is highly expressed in the retina and other sensory organs. To uncover its in vivo functions in the retina, we generated a knockout mouse model, designated “miR-183C^GT/GT,” using a gene-trap embryonic stem cell clone. We provide evidence that inactivation of the cluster results in early-onset and progressive synaptic defects of the photoreceptors, leading to abnormalities of scotopic and photopic electroretinograms with decreasedb-wave amplitude as the primary defect and progressive retinal degeneration. In addition, inactivation of themiR-183/96/182cluster resulted in global changes in retinal gene expression, with enrichment of genes important for synaptogenesis, synaptic transmission, photoreceptor morphogenesis, and phototransduction, suggesting that themiR-183/96/182cluster plays important roles in postnatal functional differentiation and synaptic connectivity of photoreceptors.

MicroRNA (miRNA) deficiency impairs the generation of T follicular helper (Tfh) cells, but the contribution of individual miRNAs to this phenotype remains poorly understood. In this study, we performed deep sequencing analysis of miRNAs expressed in Tfh cells and identified a five-miRNA signature. Analyses of mutant mice deficient of these miRNAs revealed that miR-22 and miR-183/96/182 are dispensable, but miR-155 is essential for the generation and function of Tfh cells. miR-155 deficiency led to decreased proliferation specifically at the late stage of Tfh cell differentiation and reduced CD40 ligand (CD40L) expression on antigen-specific CD4+ T cells. Mechanistically, miR-155 repressed the expression of Peli1, a ubiquitin ligase that promotes the degradation of the NF-κB family transcription factor c-Rel, which controls cellular proliferation and CD40L expression. Therefore, our study identifies a novel miR-155–Peli1–c-Rel pathway that specifically regulates Tfh cell generation and function.

Purpose: Previously, we showed that microRNA-146 (miR-146) is a pivotal negative feedback regulator of multiple nuclear factor kappa-B (NF-κB) activation pathways in retinal endothelial cells (RECs). We hypothesized that miR-146 plays an important role in diabetic retinopathy (DR) by inhibiting diabetes-induced inflammatory response in the retina. The purpose of the current study is to test this hypothesis in vivo. Methods: Lentiviruses expressing rno-miR-146a, lenti-miR-146a, and negative control oligonucleotide with scrambled sequence, lenti-miR-neg ctl, were produced. Young male Sprague-Dawley rats were injected with a single dose of streptozotocin ([STZ] 65 mg/kg) to induce diabetes. One week after diabetes, animals were injected with lentivirus intravitreally (4 μl, ∼10⁶ CFU/mL). Three months after diabetes, retinal microvascular leakage was tested by Evans blue assay; retinal function by electroretinogram (ERG). Total RNA and protein lysate were isolated from the retina for quantitative (q)RT-PCR and Western blot analyses. Results: Lenti-miR-146a robustly transduced human retinal endothelial cells (HRECs) and increased the expression of miR-146a in vitro. In vivo, intravitreal injection of lenti-miR-146a increased the expression of miR-146a in the retina, while its key downstream target genes, including CARD10, IRAK1, and TRAF6, were downregulated. Intravitreal delivery of miR-146 inhibited diabetes-induced upregulation of NF-κB downstream gene, Intercellular Adhesion Molecule 1 (ICAM1), as well as microvascular leakage and retinal functional defects. Conclusions: Intravitreal delivery of miR-146 inhibited diabetes-induced NF-κB activation and retinal microvascular and neuronal functional defects in a diabetic rat model.

The microRNA (miR)-183/96/182 cluster plays important roles in the development and functions of sensory organs, including the inner ear. Point-mutations in the seed sequence of miR-96 result in non-syndromic hearing loss in both mice and humans. However, the lack of a functionally null mutant has hampered the evaluation of the cluster’s physiological functions. Here we have characterized a loss-of-function mutant mouse model (miR-183C^GT/GT), in which the miR-183/96/182 cluster gene is inactivated by a gene-trap (GT) construct. The homozygous mutant mice show profound congenital hearing loss with severe defects in cochlear hair cell (HC) maturation, alignment, hair bundle formation and the checkboard-like pattern of the cochlear sensory epithelia. The stereociliary bundles retain an immature appearance throughout the cochlea at postnatal day (P) 3 and degenerate soon after. The organ of Corti of mutant newborn mice has no functional mechanoelectrical transduction. Several predicted target genes of the miR-183/96/182 cluster that are known to play important roles in HC development and function, including Clic5, Rdx, Ezr, Rac1, Myo1c, Pvrl3 and Sox2, are upregulated in the cochlea. These results suggest that the miR-183/96/182 cluster is essential for stereociliary bundle formation, morphogenesis and function of the cochlear HCs.