Ikhyun Jun

The HSP70 co-chaperone DNAJC14 targets misfolded pendrin for unconventional protein secretion

Mutations in SLC26A4, which encodes pendrin, are responsible for hearing loss with an enlarged vestibular aqueduct and Pendred syndrome. The most prevalent mutation in East Asia is p.H723R (His723Arg), which leads to defects in protein folding and cell-surface expression. Here we show that H723R-pendrin can be rescued to the cell surface by an HSP70 co-chaperone DNAJC14-dependent unconventional trafficking pathway. Blockade of ER-to-Golgi transport or activation of ER stress signals induced Golgi-independent cell-surface expression of H723R-pendrin and restored its cell-surface Cl−/HCO3− exchange activity. Proteomic and short interfering RNA screenings with subsequent molecular analyses showed that Hsc70 and DNAJC14 are required for the unconventional trafficking of H723R-pendrin. Moreover, DNAJC14 upregulation was able to induce the unconventional cell-surface expression of H723R-pendrin. These results indicate that Hsc70 and DNAJC14 play central roles in ER stress-associated unconventional protein secretion and are potential therapeutic targets for diseases such as Pendred syndrome, which arise from transport defects of misfolded proteins.

Internal spherical aberration by ray tracing-type aberrometry in multifocal pseudophakic eyes

PurposeTo demonstrate the results of the ray tracing-type aberrometer in measuring spherical aberration (SA) in pseudophakic eyes with monofocal intraocular lens (IOL), aspheric monofocal IOL, or aspheric diffractive multifocal IOL.MethodsTotal, corneal, and internal SA were measured using iTrace at a 6-mm pupil size in 27 eyes of 27 patients implanted with a monofocal spherical IOL (group 1: Natural, SN60AT), 30 eyes of 30 patients implanted with a monofocal aspheric IOL (group 2: IQ, SN60WF), and 30 eyes of 30 patients implanted with a multifocal aspheric IOL (group 3: ReSTOR, SN6AD1) at 3 months after cataract surgery. We compared the internal SAs of these IOLs in pupil sizes of 3, 4, 5, and 6 mm.ResultsThere were no demographic statistically significant differences among the groups. The internal SA of group 1 had a positive value. The internal SA of group 2 was −0.175±0.135 μm in 5-mm pupils and −0.227±0.253 μm in 6-mm pupils. The internal SA of group 3 was −0.072±0.128 μm in 5-mm pupils and −0.173±0.231 μm in 6-mm pupils.ConclusionMeasuring internal SA with iTrace yields relatively accurate results in all types of IOLs with adequate pupil sizes.

Pore dilatation increases the bicarbonate permeability of CFTR, ANO1 and glycine receptor anion channels.

Cellular stimuli can modulate the ion selectivity of some anion channels, such as CFTR, ANO1 and the glycine receptor (GlyR), by changing pore size. Ion selectivity of CFTR, ANO1 and GlyR is critically affected by the electric permittivity and diameter of the channel pore. Pore size change affects the energy barriers of ion dehydration as well as that of size‐exclusion of anion permeation. Pore dilatation increases the bicarbonate permeability ( P HC O3/ Cl ) of CFTR, ANO1 and GlyR. Dynamic change in P HC O3/ Cl may mediate many physiological and pathological processes.

Mutations in SLC26A1 Cause Nephrolithiasis

Nephrolithiasis, a condition in which urinary supersaturation leads to stone formation in the urinary system, affects about 5%-10% of individuals worldwide at some point in their lifetime and results in significant medical costs and morbidity. To date, mutations in more than 30 genes have been described as being associated with nephrolithiasis, and these mutations explain about 15% of kidney stone cases, suggesting that additional nephrolithiasis-associated genes remain to be discovered. To identify additional genes whose mutations are linked to nephrolithiasis, we performed targeted next-generation sequencing of 18 hypothesized candidate genes in 348 unrelated individuals with kidney stones. We detected biallelic mutations in SLC26A1 (solute carrier family 26 member 1) in two unrelated individuals with calcium oxalate kidney stones. We show by immunofluorescence, immunoblotting, and glycosylation analysis that the variant protein mimicking p.Thr185Met has defects in protein folding or trafficking. In addition, by measuring anion exchange activity of SLC26A1, we demonstrate that all the identified mutations in SLC26A1 result in decreased transporter activity. Our data identify SLC26A1 mutations as causing a recessive Mendelian form of nephrolithiasis.

Comparison of the optic nerve imaging by time-domain optical coherence tomography and Fourier-domain optical coherence tomography in distinguishing normal eyes from those with glaucoma.

PurposeTo assess agreement in cup-to-disc ratio (CDR) estimation between stereoscopic optic disc photography, time-domain optical coherence tomography (OCT), and Fourier-domain OCT, and to compare the discriminating ability of optic nerve head (ONH) parameters by time-domain OCT and Fourier-domain OCT for glaucoma detection. MethodsParticipants underwent stereoscopic photography, Stratus OCT (fast optic disc scan), and RTVue-100 (nerve head mapping), at the same visit. Vertical and horizontal CDRs (VCDR and HCDR) from stereoscopic photography were determined by averaging the results from 2 independent glaucoma specialists. VCDR, HCDR, disc area, cup area, rim area, and cup-to-disc area ratio were acquired from the 2 OCTs. Agreement was assessed by intraclass correlation coefficients (ICCs) and Bland-Altman plots. Area under the receiver operator characteristic curve was used to assess the ability of each parameter to detect glaucoma. ResultsA total of 185 eyes were used in final analysis. VCDR and HCDR measurements from RTVue were highest, followed by those from Stratus OCT and stereoscopic photography. CDRs from both OCTs showed excellent agreement with those from stereophotography (ICC, 0.80 to 0.86). Agreement in ONH parameters including CDRs between the 2 OCTs was excellent (ICC, 0.86 to 0.94). There were no statistically significant differences between the ONH parameters from the 2 OCTs with respect to ability to detect glaucoma. ConclusionsVCDR and HCDR measurement by time-domain and Fourier-domain OCTs exhibited excellent agreement with each other and agreed equally well with those by stereoscopic photography. The ONH parameters between the 2 OCTs performed similarly in determining glaucoma status.

Comparison of intraocular pressures after myopic laser-assisted subepithelial keratectomy: tonometry-pachymetry, Goldmann applanation tonometry, dynamic contour tonometry, and noncontact tonometry.

Purpose To compare intraocular pressure (IOP) measurements using a new tonometer–pachymeter device (Tonopachy), Goldmann applanation tonometry (GAT), dynamic contour tonometry (DCT), and noncontact tonometry (NCT) before and after myopic laser‐assisted subepithelial keratectomy (LASEK). Setting Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea. Design Prospective comparative observational study. Methods Nine IOP values were measured using 4 tonometers (6 IOPs by tonometer–pachymeter and 1 each by GAT, DCT, and NCT) and compared preoperatively and 3 months postoperatively. Of the 6 IOP values measured by the tonometer–pachymeter, 1 showed uncorrected IOP and 5 indicated central corneal thickness (CCT)–corrected IOPs through different formulas. Results Preoperatively and postoperatively, the means of 9 IOP values measured by 4 tonometers were statistically different. The IOP measurements by the tonometer–pachymeter correlated with all other IOP values preoperatively; however, there was no correlation with IOP measurements using DCT postoperatively. Some IOPs using the tonometer–pachymeter were interchangeable with those using GAT preoperatively, but not with DCT preoperatively or postoperatively. The corrected IOP values of the tonometer–pachymeter formula 3 and DCT did not change after surgery. The percentage change in CCT and corneal curvature and change in diopters correlated with the percentage change in IOP measurements by GAT and NCT but not with those using DCT and the tonometer–pachymeter. Conclusion Among the 9 IOP values, corrected IOP using the tonometer–pachymeter formula 3 showed similar IOP values after LASEK, as did DCT. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

A novel BEST1 mutation in autosomal recessive bestrophinopathy

PURPOSE To describe the clinical characteristics associated with a newly identified mutant of autosomal recessive bestrophinopathy (ARB) and confirm the associated physiological functional defects. METHODS Two patients with ARB from one family underwent a full ophthalmic examination, including dilated fundus examination, fundus photography, fluorescein angiography, fundus autofluorescence imaging, spectral-domain optical coherence tomography (OCT), electroretinography (ERG), and electrooculography (EOG). Subsequently, genetic analysis for bestrophin-1 (BEST1) mutations was conducted through direct Sanger sequencing. The effect of ARB-associated mutations of BEST1 on the cellular localization was determined by in vitro experiments. Whole-cell patch clamping was conducted to measure the chloride conductance of wild-type BEST1 and the identified BEST1 mutants in transfected HEK293T cells. RESULTS Two related patients (66-year-old brother and 52-year-old sister) presented with reduced visual acuity and bilateral symmetrical subretinal deposits of hyperautofluorescent materials in the posterior pole. Spectral-domain OCT showed macular thinning with submacular fluid. The female patient had a concomitant macular edema associated with branched retinal vein occlusion in the left eye, which responded well to intravitreal bevacizumab injections. Genetic analysis demonstrated that both patients were compound heterozygous for one novel (Leu40Pro) and one previously identified (Ala195Val) BEST1 variant. HEK293T cells transfected with the identified BEST1 mutant showed significantly small currents compared to those transfected with the wild-type gene, whereas cells cotransfected with mutant and wild-type BEST1 showed good chloride conductance. Cellular localization of BEST1 was well conserved to the plasma membrane in the mutants. CONCLUSIONS We have identified and described the phenotype and in vitro functional aspects of a new BEST1 mutation causing ARB. Clinically suspected ARB cases warrant genetic confirmation to confirm the diagnosis.

Calcinosis Cutis at the Tarsus of the Upper Eyelid

Calcinosis cutis involves the inappropriate deposition of calcium within the dermis layer of the skin, and is often associated with rheumatoid disease. A 42-year-old woman presented for evaluation of a hard palpable mass on the left upper eyelid. After everting the eyelid, a large papillomatous mass with a broad base was identified on the superior area of the tarsus. The lesion was partially excised posteriorly under local anesthesia, and pathologists identified the mass as calcinosis cutis. The patient had no systemic or trauma history, and the serum levels of calcium and phosphorous were normal. Idiopathic calcinosis cutis should be included in the differential diagnosis for a protruding papillomatous mass of the tarsal plate, and surgical debulking could be a viable option for large protruding lesions, although more follow-up is necessary to monitor regrowth.

ANO9/TMEM16J promotes tumourigenesis via EGFR and is a novel therapeutic target for pancreatic cancer

Background:Anoctamin (ANO)/transmembrane member 16 (TMEM16) proteins mediate diverse physiological and pathophysiological functions including cancer cell proliferation. The present study aimed to identify the role of ANOs in pancreatic cancer.Methods:In an initial screen of ANOs, ANO9/TMEM16J was overexpressed in pancreatic cancer cells, and its role in the pathogenesis of pancreatic cancer was evaluated using an integrated in vitro and in vivo approach. To determine clinical relevance of the experimental findings, the prognostic value of ANO9 was evaluated in patients with pancreatic cancer.Results:The ANO9 mRNA and protein levels were increased in pancreatic cancer-derived cells. Exogenous expression of ANO9 in PANC-1 cells significantly increased cell proliferation in cell cultures and in mice. In contrast, knockdown of ANO9 in AsPC-1, BxPC-3, and Capan-2 cells strongly inhibited cell proliferation. Mechanistic analysis suggested that physical association of ANO9 with epidermal growth factor receptor (EGFR) underlies ANO9-induced cell proliferation. Knockdown of ANO9 augmented the effects of the EGFR inhibitor and the cytotoxic agent on pancreatic cancer cell proliferation. In addition, high ANO9 expression is a poor prognostic factor in patients with pancreatic cancer.Conclusions:The ANO9/TMEM16J appears to be a clinically useful prognostic marker for pancreatic cancer and a potential therapeutic target.

Clinical Outcomes of SMILE With a Triple Centration Technique and Corneal Wavefront-Guided Transepithelial PRK in High Astigmatism

PURPOSE To comparatively investigate the clinical outcomes, vector parameters, and corneal aberrations of small incision lenticule extraction (SMILE) with a triple centration technique and corneal wavefront-guided transepithelial photorefractive keratectomy (PRK) for the correction of high astigmatism. METHODS This retrospective, comparative case series study included 89 eyes (89 patients) that received treatment for myopia with high astigmatism (≥ 2.50 diopters) using SMILE with a triple centration technique (SMILE group; 45 eyes) and corneal wavefront-guided transepithelial PRK (transepithelial PRK group; 44 eyes). Visual acuity measurement, manifest refraction, slit-lamp examination, autokeratometry, corneal topography, and evaluation of corneal wavefront aberration were performed preoperatively and at 1, 3, and 6 months after surgery. The safety, efficacy, vector parameters, and corneal aberrations at 6 months after surgery were compared between the two groups. RESULTS At 6 months after surgery, the transepithelial PRK and SMILE groups exhibited comparable mean uncorrected distance visual acuities (-0.06 ± 0.07 and -0.05 ± 0.07 logMAR, respectively), safety, efficacy, and predictability of refractive and visual outcomes. There was a slight but statistically significant difference in the correction index between the transepithelial PRK and SMILE groups (0.96 ± 0.11 and 0.91 ± 0.10, respectively). Whereas the transepithelial PRK group exhibited increased corneal spherical aberration and significantly reduced corneal coma and trefoil, no changes in aberrometric values were noted in the SMILE group. CONCLUSIONS Both SMILE with a triple centration technique and corneal wavefront-guided transepithelial PRK are effective and provide predictable outcomes for the correction of high myopic astigmatism, although slight undercorrection was observed in the SMILE group. The triple centration technique was helpful in astigmatism correction by SMILE. [J Refract Surg. 2018;34(3):156-163.].