Janet Lee

Arabidopsis Cryptochrome 2 Completes Its Posttranslational Life Cycle in the Nucleus

CRY2 is a blue light receptor regulating light inhibition of hypocotyl elongation and photoperiodic flowering in Arabidopsis thaliana. The CRY2 protein is found primarily in the nucleus, and it is known to undergo blue light–dependent phosphorylation and degradation. However, the subcellular location where CRY2 exerts its function or undergoes blue light–dependent phosphorylation and degradation remains unclear. In this study, we analyzed the function and regulation of conditionally nuclear-localized CRY2. Our results show that CRY2 mediates blue light inhibition of hypocotyl elongation and photoperiodic promotion of floral initiation in the nucleus. Consistent with this result and a hypothesis that blue light–dependent phosphorylation is associated with CRY2 function, we demonstrate that CRY2 undergoes blue light–dependent phosphorylation in the nucleus. CRY2 phosphorylation is required for blue light–dependent CRY2 degradation, but only a limited quantity of CRY2 is phosphorylated at any given moment in seedlings exposed to blue light, which explains why continuous blue light illumination is required for CRY2 degradation. Finally, we showed that CRY2 is ubiquitinated in response to blue light and that ubiquitinated CRY2 is degraded by the 26S proteasome in the nucleus. These findings demonstrate that a photoreceptor can complete its posttranslational life cycle (from protein modification, to function, to degradation) inside the nucleus.

Complement factor H genotypes impact risk of age-related macular degeneration by interaction with oxidized phospholipids

The rs1061170T/C variant encoding the Y402H change in complement factor H (CFH) has been identified by genome-wide association studies as being significantly associated with age-related macular degeneration (AMD). However, the precise mechanism by which this CFH variant impacts the risk of AMD remains largely unknown. Oxidative stress plays an important role in many aging diseases, including cardiovascular disease and AMD. A large amount of oxidized phospholipids (oxPLs) are generated in the eye because of sunlight exposure and high oxygen content. OxPLs bind to the retinal pigment epithelium and macrophages and strongly activate downstream inflammatory cascades. We hypothesize that CFH may impact the risk of AMD by modulating oxidative stress. Here we demonstrate that CFH binds to oxPLs. The CFH 402Y variant of the protective rs1061170 genotype binds oxPLs with a higher affinity and exhibits a stronger inhibitory effect on the binding of oxPLs to retinal pigment epithelium and macrophages. In addition, plasma from non-AMD subjects with the protective genotype has a lower level of systemic oxidative stress measured by oxPLs per apolipoprotein B (oxPLs/apoB). We also show that oxPL stimulation increases expression of genes involved in macrophage infiltration, inflammation, and neovascularization in the eye. OxPLs colocalize with CFH in drusen in the human AMD eye. Subretinal injection of oxPLs induces choroidal neovascularization in mice. In addition, we show that the CFH risk allele confers higher complement activation and cell lysis activity. Together, these findings suggest that CFH influences AMD risk by modulating oxidative stress, inflammation, and abnormal angiogenesis.

Formation of Nuclear Bodies of Arabidopsis CRY2 in Response to Blue Light Is Associated with Its Blue Light–Dependent Degradation

Arabidopsis thaliana cryptochrome 2 (CRY2) mediates photoperiodic promotion of floral initiation and blue light inhibition of hypocotyl elongation. It has been hypothesized that photoexcitation derepresses CRY2 by disengaging its C-terminal domain from the N-terminal PHR domain. To test this hypothesis, we analyzed activities of CRY2 fused to green fluorescent protein (GFP) at either the N terminus (GFP-CRY2) or the C terminus (CRY2-GFP). While GFP-CRY2 exerts light-dependent biochemical and physiological activities similar to those of the endogenous CRY2, CRY2-GFP showed constitutive biochemical and physiological activities. CRY2-GFP is constitutively phosphorylated, it promotes deetiolation in both dark and light, and it activates floral initiation in both long-day and short-day photoperiods. These results are consistent with the hypothesis that photoexcited CRY2 disengages its C-terminal domain from the PHR domain to become active. Surprisingly, we found that CRY2-GFP, but not GFP-CRY2, formed distinct nuclear bodies in response to blue light. Compared with GFP-CRY2 or the endogenous CRY2, CRY2-GFP degradation was significantly retarded in response to blue light, suggesting that the nuclear bodies may result from accumulation of photoexcited CRY2-GFP waiting to be degraded. Consistent with this interpretation, we showed that both GFP-CRY2 and endogenous CRY2 formed nuclear bodies in the presence of the 26S-proteasome inhibitors that block blue light–dependent CRY2 degradation.

TCF7L2 Variation and Proliferative Diabetic Retinopathy

Proliferative diabetic retinopathy (PDR) is the most severe vision-threatening complication of diabetes. For investigation of genetic association between TCF7L2 and PDR in Caucasian type 2 diabetes mellitus (T2DM) and its functional consequences, 383 T2DM patients with PDR (T2DM-PDR) and 756 T2DM patients without diabetic retinopathy (T2DM–no DR) were genotyped with rs7903146 in TCF7L2. We found that risk allele (T) frequency of rs7903146 was significantly higher in T2DM-PDR patients (allelic P = 2.52E-04). In lymphoblastoid cells induced to undergo endoplasmic reticulum (ER) stress by treatment of tunicamycin, higher fold change of TCF7L2 and VEGFA mRNA levels were observed in rs7903146-TT cells than in rs7903146-CC cells (P = 0.02 for TCF7L2; P = 0.004 for VEGFA), suggesting that ER stress plays a role in PDR pathogenesis. Silencing TCF7L2 resulted in decreased mRNA levels of both TCF7L2 and VEGFA (P < 0.001). Retinas of oxygen-induced retinopathy mice (a model for PDR) had higher TCF7L2 and VEGFA mRNA levels than those of controls (P = 2.9E-04 for TCF7L2; P = 1.9E-07 for VEGFA). Together, data from our study show that TCF7L2-rs7903146 is associated with PDR in Caucasian T2DM and suggest that TCF7L2 promotes pathological retinal neovascularization via ER stress–dependent upregulation of VEGFA.

A novel missense SNRNP200 mutation associated with autosomal dominant retinitis pigmentosa in a Chinese family.

The SNRNP200 gene encodes hBrr2, a helicase essential for pre-mRNA splicing. Six mutations in SNRNP200 have recently been discovered to be associated with autosomal dominant retinitis pigmentosa (adRP). In this work, we analyzed a Chinese family with adRP and identified a novel missense mutation in SNRNP200. To identify the genetic defect in this family, exome of the proband was captured and sequencing analysis was performed to exclude known genetic defects and find possible pathogenic mutations. Subsequently, candidate mutations were validated in affected family members using Sanger sequencing. A novel missense mutation, c.2653C>G transition (p.Q885E), in exon 20 of SNRNP200 was identified. The mutation co-segregated with the disease phenotype over four generations and was absent in 100 normal unaffected individuals. This mutation occurs at highly conserved position in hBrr2 and is predicted to have a functional impact, suggesting that hBrr2-dependent small nuclear riboproteins (snRNPs) unwinding and spliceosome activation is important in the pathogenesis of some variants of RP.

Using Problem-Based Learning to Train Evaluators

As the evaluation profession has continued to grow and develop, there has been a corresponding concern about how to properly train future evaluation practitioners. Those who teach evaluation strive to develop training opportunities that create the appropriate balance of the practical, how-to knowledge of evaluation with the burgeoning theoretical knowledge that undergirds responsible evaluation practice. There is a recognized need to move beyond traditional teaching methods to ones that are more engaging and “hands on” to help students understand the interactive nature of program evaluation. Problem-based learning is an experiential learning approach that can integrate the need to balance self-study of theory and practice, along with the need to familiarize students with the dynamic, interactive nature of program evaluation. This article serves as an introduction to the problem-based learning approach and describes this instructional method applied to teaching a graduate-level course in evaluation procedures.

Impact of depression and anxiety on the quality of life of constipated patients.

Constipation negatively affects quality of life (QOL), however, the specific mechanisms through which this relationship occurs are unclear. The present study examined anxiety and depression as potential mediators of the relationship between constipation severity and QOL in a sample of 142 constipated patients. Results indicated that depression symptom severity mediated the relationship between constipation severity and mental health-related QOL. For patients meeting diagnostic criteria for Major Depressive Disorder, indirect effects were observed in the relationship between constipation severity and both physical and mental health-related QOL. Anxiety did not contribute to this model. Treating depression may be useful in improving QOL in severely constipated patients, which highlights the importance of psychological screening and treatment referrals in primary care settings.

Clinical and Genetic Identification of a Large Chinese Family with Autosomal Dominant Retinitis Pigmentosa

Abstract Background: Retinitis pigmentosa (RP) is a group of inherited retinal dystrophies characterized by night blindness, progressive peripheral visual field loss, and loss of central vision. Fifty-three RP pathogenic genes are responsible for RP. Pre-mRNA processing factor 31(PRPF31) gene is the third most common cause of autosomal dominant retinitis pigmentosa (adRP), and so far more than 40 mutations in PRPF31 have been detected. Purpose: To identify the underlying genetic defect in a five-generation Chinese family affected with adRP and to study the genotype-phenotype relationship of this family. Methods: Detailed clinical investigations were undertaken and peripheral blood samples were collected from 25 individuals. Microsatellite (STR) markers tightly linked to genes known to be responsible for adRP were selected for linkage analysis. Exons and adjacent splice junctions of the candidate gene were amplified and sequenced. Results: This adRP family exhibited an incomplete penetrance of the RP phenotype. In affected individuals, age of disease onset was from infancy to 4 years of age. Typical RP features were associated with this mutation. Linkage analysis identified a maximum two-point LOD score of 3.20 with D19S418, which is close to PRPF31. A mutation PRPF31: (c.358-359 del AA) was identified by linkage analysis. Conclusions: A PRPF31 mutation was identified to be responsible for adRP in a large Chinese family. Our findings expand the mutation spectrum of RP in the Chinese population.

Associations between factors related to atopic disease and glaucoma in the National Health and Nutrition Examination Survey

Introduction: Previous studies have suggested associations between glaucoma and serum sensitization to specific allergens. The purpose of this study was to examine associations between inciting factors for atopic disease, atopic diseases and symptoms, and glaucoma in the 2005–2006 National Health and Nutrition Examination Survey. Methods: The study population included adult participants of National Health and Nutrition Examination Survey 2005–2006. Inciting factors for atopic disease included pet ownership, mildew/musty smell in home, cockroaches in home, use of water treatment devices, and crowded living conditions. Atopic diseases and symptoms included hay fever, eczema, any allergy, sneezing problems, and sinus infections. The outcome was glaucoma defined by the Rotterdam criteria. Covariates included age, gender, ethnicity, and allergy-related medication use. Logistic regression was used to examine associations between each exposure and glaucoma prevalence, controlling for all covariates. Statistical analyses were weighted by the National Health and Nutrition Examination Survey multistage sampling design. Results: The weighted study population included 83,205,587 subjects, of whom 2,657,336 (3.2%) had glaucoma. After adjusting for covariates, factors associated with increased glaucoma included cat ownership (odds ratio =1.99, 95% confidence interval = 1.02–3.87) and mildew/musty smell in home (odds ratio = 1.95, 95% confidence interval = 0.99–3.84; borderline significance), while history of eczema was associated with decreased glaucoma (odds ratio = 0.27, 95% confidence interval = 0.02–0.99). Conclusion: In National Health and Nutrition Examination Survey, self-reported cat ownership is associated with increased glaucoma prevalence, while a mildew/musty smell in home may have a borderline association with increased glaucoma prevalence. These findings are possibly related to laboratory associations identified in the same population and further studies are needed to identify potential mechanisms to explain these associations.

Evaluation of the safety of sclerotomy incision in patients with choroidal colobomas with/without associated microcornea.

Purpose: Whether the position of the ora serrata is normal in patients with choroidal colobomas remains unknown. The aim of this study was to measure the distance between the ora serrata and limbus in these patients and define safe sclerotomy sites for standard three-port pars plana vitrectomy. Methods: Twelve patients with choroidal colobomas with normal corneas (Group 1) and 11 patients with choroidal colobomas with microcornea (Group 2) were included in the study. Twelve patients with simple retinal detachment served as control subjects. All participants underwent vitrectomy. The distance between the limbus and ora serrata, corneal diameter, and ocular axial length were measured. Results: The average corneal diameter was 10.9 mm in Group 1, 7.9 mm in Group 2, and 11.4 mm in the control group. The average distance between the limbus and ora serrata was 6.3 mm in Group 1, 7.6 mm in Group 2, and 6.2 mm in the control group. There were significant differences in the distance between the limbus and ora serrata among the 3 groups (analysis of variance test, P < 0.05). Conclusion: Our study confirmed that it is safe to perform a sclerotic puncture 4 mm posterior to the limbus for vitrectomy in patients with choroidal colobomas with or without microcornea.