Tear Film miRNAs and Their Association With Human Dry Eye Disease

PURPOSE

miRNAs can regulate inflammatory pathways. The purpose of this work was to determine if inflammatory-related tear film miRNAs are associated with extracellular vesicles (EVs) in human non-Sjögren's Syndrome dry eye disease (DED) participants.

METHODS

Five DED and 5 non-DED human participants were recruited. Tears samples were collected by washing the ocular surface of both eyes with phosphate buffered saline, pooling samples from the right and left eyes, and purifying EVs from the samples with a polyethylene glycol (PEG) 8000 precipitation procedure. Samples were directly analyzed via ELISA or transmission electron microscopy (TEM), or RNA was isolated first from the EVs and evaluated with RNA-Seq.

RESULTS

EVs were identified in the tear film of both groups using TEM and ELISA. Following EV purification and RNA isolation, RNA-Seq determined that there were 126 EV miRNAs differentially expressed between the two groups when comparing their RNA cargoes. Ingenuity Pathways Analysis found 9 upregulated miRNAs that were associated with inflammation (miR-127-5p, miR-1273h-3p, miR-1288-5p, miR-130b-5p, miR-139-3p, miR-1910-5p, miR-203b-5p, miR-22-5p, and miR-4632-3p; all p < 0.049; fold regulation range = 1.43-1.67).

CONCLUSION

This study determined that EVs are present in the tear film and that tear EVs contain miRNAs that may be associated with DED inflammatory pathways.

Recombinant GABA(C) receptors expressed in rat hippocampal neurons after infection with an adenovirus containing the human rho1 subunit

1. A recombinant adenovirus was generated with the human rho1 GABA(C) receptor subunit (adeno-rho). Patch-clamp and antibody staining were employed to confirm functional expression of recombinant rho1 receptors after infection of human embryonic kidney cells (HEK293 cell line), human embryonic retinal cells (911 cell line), dissociated rat hippocampal neurons and cultured rat hippocampal slices. 2. Standard whole-cell recording and Western blot analysis using rho1 GABA(C) receptor antibodies revealed that recombinant rho1 receptors were expressed in HEK293 and 911 cells after adeno-rho infection and exhibited properties similar to those of rho1 receptors after standard transfection. 3. Cultured rat hippocampal neurons (postnatal day (P)3-P5) did not show a native GABA(C)-like current. After adeno-rho infection, however, a GABA(C)-like current appeared in 70-90 % of the neurons. 4. Five days after infection, expression of GABA(C) receptors in hippocampal neurons significantly decreased native GABA(A) receptor currents from 1200 +/- 300 to 150 +/- 70 pA (n = 10). The native glutamate-activated current was unchanged. 5. Hippocampal slices (P8) did not show a native GABA(C)-like current, although recombinant rho1 receptors could be expressed in cultured hippocampal slices after adeno-rho infection. 6. These data indicate that an adenovirus can be used to express recombinant GABA(C) receptors in hippocampal neurons. This finding could represent an important step towards the gene therapy of CNS receptor-related diseases.

Regulation of recombinant gamma-aminobutyric acid (GABA)(A) and GABA(C) receptors by protein kinase C

Activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate induced a continuous decrease in the gamma-aminobutyric acid (GABA)-activated current amplitude from recombinant GABA receptors (formed by rho1 or alphabetagamma subunits) expressed in Xenopus oocytes. This decline was due to internalization of receptors from the plasma membrane as confirmed by a decrease in surface fluorescence with green fluorescence protein-tagged receptors as well as a concomitant decrease in surface [(3)H]GABA binding. PMA specifically caused internalization of GABA receptors, but not neuronal acetylcholine receptors (alpha(7) or alpha(4)beta(2)), indicating the internalization was not a general, nonspecific phenomenon. Mutation of rho1 PKC phosphorylation sites, identified by in vitro phosphorylation, did not prevent GABA receptor internalization, nor did coexpression of the rho1 M3-M4 intracellular loop along with rho1 GABA receptors. It is likely that PKC-mediated phosphorylation of other proteins, rather than rho1 itself, was required for the internalization. Both rho1 and alphabetagamma receptors did not degrade after phorbol 12-myristate 13-acetate-induced internalization, but returned to the membrane surface within 24 h. These data suggest internalized receptors can exist in an intracellular compartment that can be delivered back to the plasma membrane. Thus, by regulating GABA receptor surface expression, PKC may play a key role in the regulation of GABA-mediated inhibition.

Inhibition of transcription elongation in the HER-2/neu coding sequence by triplex-directed covalent modification of the template strand

Triplex formation may be of potential utility to inhibit the expression of individual genes. We describe the formation of a triple helix in the coding sequence of the HER-2/neu gene. In vitro transcription analysis in the presence and absence of triplex formation demonstrates that an unmodified DNA triplex-forming oligonucleotide is incapable of inhibiting RNA polymerase elongation. Triplex formation by an oligonucleotide-psoralen conjugate was used to form a covalent photoadduct with a thymine on the nontemplate strand of the HER-2/neu gene. In the native HER-2/neu gene, covalent attachment of the triplex-forming oligonucleotide to the nontemplate strand did not prevent RNA polymerase elongation. Using HER-2/neu point mutants that would place the target thymine on the template strand, we demonstrated that covalent modification of the template strand was necessary to inhibit RNA polymerase elongation. Based on these data, we synthesized oligonucleotide-alkylator conjugates that would react with a specific guanine residue on the template strand of the HER-2/neu coding sequence. The oligonucleotide-alkylator conjugates inhibited transcription elongation by T7 RNA polymerase and eukaryotic RNA polymerase II from a HeLa nuclear extract. These studies demonstrate the successful application of triplex-forming oligonucleotide-alkylator conjugates to inhibit transcription elongation in the HER-2/neu gene, and show that covalent modification of the DNA strand used as the transcription template is necessary to prevent RNA polymerase elongation.

Cloning, expression, and chromosomal localization of mouse liver bile acid CoA:amino acid N-acyltransferase

A mouse liver lambda Zap XR cDNA library was screened using the coding region of human bile acid CoA:amino acid N-acyltransferase (BAT) cDNA as a probe. Ten positive clones were isolated and purified, two of which apparently possessed complete open reading frames for BAT based on sequence analysis of the ends of the cDNAs. One clone (mBAT#9) was selected for sequence analysis and characterization. mBAT#9 is 1869 basepairs in length and the full-length cDNA possesses a 189 basepair 5'-nontranslated region, an open-reading frame of 1260 basepairs, and a 404 basepair 3'-nontranslated region followed by a poly(A) tail. The open-reading frame codes for a 420 amino acid protein with a calculated molecular mass of 46,525 daltons. The structural gene for mBAT was mapped to mouse Chromosome 4. The amino acid sequence of mBAT is 69% identical and 84% similar to that of hBAT, and 86% identical and 95% similar to that of kan-1, a putative rat liver BAT. Enzymatically active mBAT was expressed in E. coli using the bacterial expression vector pKK233-2. Immunoblot analysis of expressed mBAT with rabbit anti-human BAT polyclonal antibodies detected a single protein with a molecular mass of approximately 45,000 daltons. Cytosol from cells transformed with mBAT#9/pKK233-2 possessed significant amounts of BAT-catalyzed conjugating activity with taurine as substrate but the expressed enzyme did not use glycine or fluoro-beta-alanine as substrates. The K(m) value for taurine was 1.9 mM +/- 0.1 mM in reactions with cholyl CoA as a cosubstrate. The specificity of mBAT for taurine as a substrate was confirmed by the demonstration, using HPLC-electrospray ionization mass spectrometry, that mouse gallbladder bile contained only taurine conjugates of bile acids. The identification of the types of amino acid conjugates of bile acids present in mouse bile had not been previously reported. These results indicate that a taurine-specific form of BAT has been cloned and expressed from mouse liver.