Missense variants in ANO4 cause sporadic encephalopathic or familial epilepsy with evidence for a dominant-negative effect.

Anoctamins are a family of Ca2+-activated proteins that may act as ion channels and/or phospholipid scramblases with limited understanding of function and disease association. Here, we identified five de novo and two inherited missense variants in ANO4 (alias TMEM16D) as a cause of fever-sensitive developmental and epileptic or epileptic encephalopathy (DEE/EE) and generalized epilepsy with febrile seizures plus (GEFS+) or temporal lobe epilepsy. In silico modeling of the ANO4 structure predicted that all identified variants lead to destabilization of the ANO4 structure. Four variants are localized close to the Ca2+ binding sites of ANO4, suggesting impaired protein function. Variant mapping to the protein topology suggests a preliminary genotype-phenotype correlation. Moreover, the observation of a heterozygous ANO4 deletion in a healthy individual suggests a dysfunctional protein as disease mechanism rather than haploinsufficiency. To test this hypothesis, we examined mutant ANO4 functional properties in a heterologous expression system by patch-clamp recordings, immunocytochemistry, and surface expression of annexin A5 as a measure of phosphatidylserine scramblase activity. All ANO4 variants showed severe loss of ion channel function and DEE/EE associated variants presented mild loss of surface expression due to impaired plasma membrane trafficking. Increased levels of Ca2+-independent annexin A5 at the cell surface suggested an increased apoptosis rate in DEE-mutant expressing cells, but no changes in Ca2+-dependent scramblase activity were observed. Co-transfection with ANO4 wild-type suggested a dominant-negative effect. In summary, we expand the genetic base for both encephalopathic sporadic and inherited fever-sensitive epilepsies and link germline variants in ANO4 to a hereditary disease.

Declining incidence and improving survival of ocular and orbital lymphomas in the US between 1995 and 2018.

This epidemiological study examined ocular and orbital lymphomas in the United States from 1995 to 2018, using data from the North American Association of Central Cancer Registries database of 87,543 patients with ocular and adnexal malignancies. We identified 17,878 patients (20.4%) with ocular and orbital lymphomas, with an age-standardized incidence rate (ASIR) of 2.6 persons per million (ppm). The incidence was the highest in the orbit (ASIR = 1.24), followed by the conjunctiva (ASIR = 0.57). Non-Hodgkin B-cell lymphoma was the most prevalent subtype (85.4%), particularly marginal-zone lymphoma (45.7%). Racial disparities were noted, with Asia-Pacific Islanders showing the highest incidence (orbit, 1.3 ppm). The incidence increased significantly from 1995 to 2003 (Average Percent Change, APC = 2.1%) but declined thereafter until 2018 (APC = - 0.7%). 5-year relative survival (RS) rates varied, with the highest rate for conjunctival lymphoma (100%) and the lowest for intraocular lymphoma (70.6%). Survival rates have generally improved, with an annual increase in the 5-year RS of 0.45%. This study highlights the changing epidemiological landscape, pointing to initial increases and subsequent decreases in incidence until 2003, with survival improvements likely due to advancements in treatment. These findings underscore the need for further research to investigate the root causes of these shifts and the declining incidence of ocular lymphoma.

Exploring the Impact of Saccharin on Neovascular Age-Related Macular Degeneration: A Comprehensive Study in Patients and Mice.

Purpose: We aimed to determine the impact of artificial sweeteners (AS), especially saccharin, on the progression and treatment efficacy of patients with neovascular age-related macular degeneration (nAMD) under anti-vascular endothelial growth factor (anti-VEGF-A) treatment. Methods: In a cross-sectional study involving 46 patients with nAMD undergoing intravitreal anti-VEGF therapy, 6 AS metabolites were detected in peripheral blood using liquid chromatography - tandem mass spectrometry (LC-MS/MS). Disease features were statistically tested against these metabolite levels. Additionally, a murine choroidal neovascularization (CNV) model, induced by laser, was used to evaluate the effects of orally administered saccharin, assessing both imaging outcomes and gene expression patterns. Polymerase chain reaction (PCR) methods were used to evaluate functional expression of sweet taste receptors in a retinal pigment epithelium (RPE) cell line. Results: Saccharin levels in blood were significantly higher in patients with well-controlled CNV activity (P = 0.004) and those without subretinal hyper-reflective material (P = 0.015). In the murine model, saccharin-treated mice exhibited fewer leaking laser scars, lesser occurrence of bleeding, smaller fibrotic areas (P < 0.05), and a 40% decrease in mononuclear phagocyte accumulation (P = 0.06). Gene analysis indicated downregulation of inflammatory and VEGFR-1 response genes in the treated animals. Human RPE cells expressed taste receptor type 1 member 3 (TAS1R3) mRNA and reacted to saccharin stimulation with changes in mRNA expression. Conclusions: Saccharin appears to play a protective role in patients with nAMD undergoing intravitreal anti-VEGF treatment, aiding in better pathological lesion control and scar reduction. The murine study supports this observation, proposing saccharin's potential in mitigating pathological VEGFR-1-induced immune responses potentially via the RPE sensing saccharin in the blood stream.

Splenic monocytes drive pathogenic subretinal inflammation in age-related macular degeneration.

Age-related macular degeneration (AMD) is invariably associated with the chronic accumulation of activated mononuclear phagocytes in the subretinal space. The mononuclear phagocytes are composed of microglial cells but also of monocyte-derived cells, which promote photoreceptor degeneration and choroidal neovascularization. Infiltrating blood monocytes can originate directly from bone marrow, but also from a splenic reservoir, where bone marrow monocytes develop into angiotensin II receptor (ATR1)+ splenic monocytes. The involvement of splenic monocytes in neurodegenerative diseases such as AMD is not well understood. Using acute inflammatory and well-phenotyped AMD models, we demonstrate that angiotensin II mobilizes ATR1+ splenic monocytes, which we show are defined by a transcriptional signature using single-cell RNA sequencing and differ functionally from bone marrow monocytes. Splenic monocytes participate in the chorio-retinal infiltration and their inhibition by ATR1 antagonist and splenectomy reduces the subretinal mononuclear phagocyte accumulation and pathological choroidal neovascularization formation. In aged AMD-risk ApoE2-expressing mice, a chronic AMD model, ATR1 antagonist and splenectomy also inhibit the chronic retinal inflammation and associated cone degeneration that characterizes these mice. Our observation of elevated levels of plasma angiotensin II in AMD patients, suggests that similar events take place in clinical disease and argue for the therapeutic potential of ATR1 antagonists to inhibit splenic monocytes for the treatment of blinding AMD.

Evidence of Cytolysin A nanopore incorporation in mammalian cells assessed by a graphical user interface.

Technologies capable of assessing cellular metabolites with high precision and temporal resolution are currently limited. Recent developments in the field of nanopore sensors allow the non-stochastic quantification of metabolites, where a nanopore is acting as an electrical transducer for selective substrate binding proteins (SBPs). Here we show that incorporation of the pore-forming toxin Cytolysin A (ClyA) into the plasma membrane of Chinese hamster ovary cells (CHO-K1) results in the appearance of single-channel conductance amenable to multiplexed automated patch-clamp (APC) electrophysiology. In CHO-K1 cells, SBPs modify the ionic current flowing though ClyA nanopores, thus demonstrating its potential for metabolite sensing of living cells. Moreover, we developed a graphical user interface for the analysis of the complex signals resulting from multiplexed APC recordings. This system lays the foundation to bridge the gap between recent advances in the nanopore field (e.g., proteomic and transcriptomic) and potential cellular applications.

Increased plasma level of terminal complement complex in AMD patients: potential functional consequences for RPE cells.

Purpose: Polymorphisms in complement genes are risk-associated for age-related macular degeneration (AMD). Functional analysis revealed a common deficiency to control the alternative complement pathway by risk-associated gene polymorphisms. Thus, we investigated the levels of terminal complement complex (TCC) in the plasma of wet AMD patients with defined genotypes and the impact of the complement activation of their plasma on second-messenger signaling, gene expression, and cytokine/chemokine secretion in retinal pigment epithelium (RPE) cells. Design: Collection of plasma from patients with wet AMD (n = 87: 62% female and 38% male; median age 77 years) and controls (n = 86: 39% female and 61% male; median age 58 years), grouped for risk factor smoking and genetic risk alleles CFH 402HH and ARMS2 rs3750846, determination of TCC levels in the plasma, in vitro analysis on RPE function during exposure to patients' or control plasma as a complement source. Methods: Genotyping, measurement of TCC concentrations, ARPE-19 cell culture, Ca2+ imaging, gene expression by qPCR, secretion by multiplex bead analysis of cell culture supernatants. Main outcome measures: TCC concentration in plasma, intracellular free Ca2+, relative mRNA levels, cytokine secretion. Results: TCC levels in the plasma of AMD patients were five times higher than in non-AMD controls but did not differ in plasma from carriers of the two risk alleles. Complement-evoked Ca2+ elevations in RPE cells differed between patients and controls with a significant correlation between TCC levels and peak amplitudes. Comparing the Ca2+ signals, only between the plasma of smokers and non-smokers, as well as heterozygous (CFH 402YH) and CFH 402HH patients, revealed differences in the late phase. Pre-stimulation with complement patients' plasma led to sensitization for complement reactions by RPE cells. Gene expression for surface molecules protective against TCC and pro-inflammatory cytokines increased after exposure to patients' plasma. Patients' plasma stimulated the secretion of pro-inflammatory cytokines in the RPE. Conclusion: TCC levels were higher in AMD patients but did not depend on genetic risk factors. The Ca2+ responses to patients' plasma as second-messenger represent a shift of RPE cells to a pro-inflammatory phenotype and protection against TCC. We conclude a substantial role of high TCC plasma levels in AMD pathology.

Retinal TRP channels: Cell-type-specific regulators of retinal homeostasis and multimodal integration.

Transient receptor potential (TRP) channels are a widely expressed family of 28 evolutionarily conserved cationic ion channels that operate as primary detectors of chemical and physical stimuli and secondary effectors of metabotropic and ionotropic receptors. In vertebrates, the channels are grouped into six related families: TRPC, TRPV, TRPM, TRPA, TRPML, and TRPP. As sensory transducers, TRP channels are ubiquitously expressed across the body and the CNS, mediating critical functions in mechanosensation, nociception, chemosensing, thermosensing, and phototransduction. This article surveys current knowledge about the expression and function of the TRP family in vertebrate retinas, which, while dedicated to transduction and transmission of visual information, are highly susceptible to non-visual stimuli. Every retinal cell expresses multiple TRP subunits, with recent evidence establishing their critical roles in paradigmatic aspects of vertebrate vision that include TRPM1-dependent transduction of ON bipolar signaling, TRPC6/7-mediated ganglion cell phototransduction, TRP/TRPL phototransduction in Drosophila and TRPV4-dependent osmoregulation, mechanotransduction, and regulation of inner and outer blood-retina barriers. TRP channels tune light-dependent and independent functions of retinal circuits by modulating the intracellular concentration of the 2nd messenger calcium, with emerging evidence implicating specific subunits in the pathogenesis of debilitating diseases such as glaucoma, ocular trauma, diabetic retinopathy, and ischemia. Elucidation of TRP channel involvement in retinal biology will yield rewards in terms of fundamental understanding of vertebrate vision and therapeutic targeting to treat diseases caused by channel dysfunction or over-activation.

FoxP3 expression by retinal pigment epithelial cells: transcription factor with potential relevance for the pathology of age-related macular degeneration.

BACKGROUND: Forkhead-Box-Protein P3 (FoxP3) is a transcription factor and marker of regulatory T cells, converting naive T cells into Tregs that can downregulate the effector function of other T cells. We previously detected the expression of FoxP3 in retinal pigment epithelial (RPE) cells, forming the outer blood-retina barrier of the immune privileged eye. METHODS: We investigated the expression, subcellular localization, and phosphorylation of FoxP3 in RPE cells in vivo and in vitro after treatment with various stressors including age, retinal laser burn, autoimmune inflammation, exposure to cigarette smoke, in addition of IL-1ß and mechanical cell monolayer destruction. Eye tissue from humans, mouse models of retinal degeneration and rats, and ARPE-19, a human RPE cell line for in vitro experiments, underwent immunohistochemical, immunofluorescence staining, and PCR or immunoblot analysis to determine the intracellular localization and phosphorylation of FoxP3. Cytokine expression of stressed cultured RPE cells was investigated by multiplex bead analysis. Depletion of the FoxP3 gene was performed with CRISPR/Cas9 editing. RESULTS: RPE in vivo displayed increased nuclear FoxP3-expression with increases in age and inflammation, long-term exposure of mice to cigarette smoke, or after laser burn injury. The human RPE cell line ARPE-19 constitutively expressed nuclear FoxP3 under non-confluent culture conditions, representing a regulatory phenotype under chronic stress. Confluently grown cells expressed cytosolic FoxP3 that was translocated to the nucleus after treatment with IL-1ß to imitate activated macrophages or after mechanical destruction of the monolayer. Moreover, with depletion of FoxP3, but not of a control gene, by CRISPR/Cas9 gene editing decreased stress resistance of RPE cells. CONCLUSION: Our data suggest that FoxP3 is upregulated by age and under cellular stress and might be important for RPE function.

Factor H-related protein 1 (FHR-1) is associated with atherosclerotic cardiovascular disease.

Atherosclerotic cardiovascular disease (ACVD) is a lipid-driven inflammatory disease and one of the leading causes of death worldwide. Lipid deposits in the arterial wall lead to the formation of plaques that involve lipid oxidation, cellular necrosis, and complement activation, resulting in inflammation and thrombosis. The present study found that homozygous deletion of the CFHR1 gene, which encodes the plasma complement protein factor H-related protein 1 (FHR-1), was protective in two cohorts of patients with ACVD, suggesting that FHR-1 accelerates inflammation and exacerbates the disease. To test this hypothesis, FHR-1 was isolated from human plasma and was found to circulate on extracellular vesicles and to be deposited in atherosclerotic plaques. Surface-bound FHR-1 induced the expression of pro-inflammatory cytokines and tissue factor in both monocytes and neutrophils. Notably, plasma concentrations of FHR-1, but not of factor H, were significantly (p < 0.001) elevated in patients with ACVD, and correlated with the expression of the inflammation markers C-reactive protein, apolipoprotein serum amyloid protein A, and neopterin. FHR-1 expression also significantly correlated with plasma concentrations of low-density lipoprotein (LDL) (p < 0.0001) but not high-density lipoprotein (HDL). Taken together, these findings suggest that FHR-1 is associated with ACVD.

Prediction of Functional Consequences of Missense Mutations in ANO4 Gene.

The anoctamin (TMEM16) family of transmembrane protein consists of ten members in vertebrates, which act as Ca2+-dependent ion channels and/or Ca2+-dependent scramblases. ANO4 which is primarily expressed in the CNS and certain endocrine glands, has been associated with various neuronal disorders. Therefore, we focused our study on prioritizing missense mutations that are assumed to alter the structure and stability of ANO4 protein. We employed a wide array of evolution and structure based in silico prediction methods to identify potentially deleterious missense mutations in the ANO4 gene. Identified pathogenic mutations were then mapped to the modeled human ANO4 structure and the effects of missense mutations were studied on the atomic level using molecular dynamics simulations. Our data show that the G80A and A500T mutations significantly alter the stability of the mutant proteins, thus providing new perspective on the role of missense mutations in ANO4 gene. Results obtained in this study may help to identify disease associated mutations which affect ANO4 protein structure and function and might facilitate future functional characterization of ANO4.

Effects of TNFα receptor TNF-Rp55- or TNF-Rp75- deficiency on corneal neovascularization and lymphangiogenesis in the mouse.

Tumor necrosis factor (TNF)α is an inflammatory cytokine likely to be involved in the process of corneal inflammation and neovascularization. In the present study we evaluate the role of the two receptors, TNF-receptor (TNF-R)p55 and TNF-Rp75, in the mouse model of suture-induced corneal neovascularization and lymphangiogenesis. Corneal neovascularization and lymphangiogenesis were induced by three 11-0 intrastromal corneal sutures in wild-type (WT) C57BL/6J mice and TNF-Rp55-deficient (TNF-Rp55d) and TNF-Rp75-deficient (TNF-Rp75d) mice. The mRNA expression of VEGF-A, VEGF-C, Lyve-1 and TNFα and its receptors was quantified by qPCR. The area covered with blood- or lymphatic vessels, respectively, was analyzed by immunohistochemistry of corneal flatmounts. Expression and localization of TNFα and its receptors was assessed by immunohistochemistry of sagittal sections and Western Blot. Both receptors are expressed in the murine cornea and are not differentially regulated by the genetic alteration. Both TNF-Rp55d and TNF-Rp75d mice showed a decrease in vascularized area compared to wild-type mice 14 days after suture treatment. After 21 days there were no differences detectable between the groups. The number of VEGF-A-expressing macrophages did not differ when comparing WT to TNF-Rp55d and TNF-Rp75d. The mRNA expression of lymphangiogenic markers VEGF-C or LYVE-1 does not increase after suture in all 3 groups and lymphangiogenesis showed a delayed effect only for TNF-Rp75d. TNFα mRNA and protein expression increased after suture treatment but showed no difference between the three groups. In the suture-induced mouse model, TNFα and its ligands TNF-Rp55 and TNF-Rp75 do not play a significant role in the pathogenesis of neovascularisation and lymphangiogenesis.

Factor H-related protein 1: a complement regulatory protein and guardian of necrotic-type surfaces.

Factor H-related protein 1 (FHR-1) is a member of the factor H protein family, which is involved in regulating innate immune complement reactions. Genetic modification of the encoding gene, CFHR1 on human chromosome 1, is involved in diseases such as age-related macular degeneration, C3 glomerulopathy and atypical haemolytic uraemic syndrome, indicating an important role for FHR-1 in human health. Recent research data demonstrate that FHR-1 levels increase in IgA nephropathy and anti-neutrophilic cytoplasmic autoantibodies (ANCA) vasculitis and that FHR-1 induces strong inflammation in monocytes on necrotic-type surfaces, suggesting a complement-independent role. These new results increase our knowledge about the role of this complement protein in pathology and provide a new therapeutic target, particularly in the context of inflammatory diseases induced by necrosis. This review summarizes current knowledge about FHR-1 and discusses its role in complement reactions and inflammation. LINKED ARTICLES: This article is part of a themed issue on Canonical and non-canonical functions of the complement system in health and disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.14/issuetoc.

Second primary malignancies of eye and ocular adnexa after a first primary elsewhere in the body.

PURPOSE: The eye and its adnexal structures can give rise to first or consecutive primary malignancies or to encounter metastasis. Our aim was to define the characteristics of the second primary neoplasms affecting the eye and its adnexa and find the risk modifying factors for them after malignancies elsewhere in the body. METHODS: We have queried the Surveillance, Epidemiology and End-Results "SEER"-9 program of the National Cancer Institute for the malignancies of the eye and its adnexa that occurred between 1973 and 2015. The malignancies were ordered chronologically according to their incidence: first or second primary malignancies. The tumors were classified according to ICD-O-3 classification. Standardized incidence ratios (SIR) and survival probabilities were calculated for subgroups. RESULTS: Among 3,578,950 cancer patients, 1203 experienced a second malignancies of the eye and its adnexa. The first malignancy was diagnosed between 50 and 69 years of age in 58.94% of them. The eyelid showed 280 events, while 50 in lacrimal gland, 181 in the orbit, 21 in the overlapping lesions, 15 in optic nerve, 148 in the conjunctiva, 9 in the cornea, 6 in the Retina, 379 in the choroid, and 93 in the ciliary body. The SIR of a second malignancy after a prior non-Hodgkin lymphoma was 2.42, and in case of previous skin carcinomas it was 3.02, melanoma of skin, and 2.13 and 1.58 in oral cavity/pharynx malignancies. The second ocular and adnexal neoplasms increased steadily over the 5-year periods on contrary to first primary neoplasms. The survival of patients affected with first ocular and adnexal neoplasms was significantly higher than those with second ocular and adnexal neoplasms. On the other side, second primary ocular and adnexal tumors showed a better survival than second primary malignancies elsewhere. CONCLUSIONS: The epidemiological differences between first and second ocular and adnexal primaries suggest different underlying mechanisms. Careful ocular examination should be integrated in the long-term follow-up plan of cancer patients. Special attention should be given to patients with non-Hodgkin's lymphoma and melanoma as first primary.

Uveal melanoma-associated cancers revisited.

BACKGROUND: Uveal melanoma (UM) is the most common primary ocular malignancy of adults. A small group of patients was found to express familial predisposition. Moreover, it may be preceded or followed by other malignancies elsewhere in the body. We aim to compare the incidence of UM and other associated cancers and study the factors that may influence each condition. PATIENTS AND METHODS: We have collected the data from the Surveillance, Epidemiology and End Results database of nine US cancer registries for UM patients between 1973 and 2015. We calculated the standardised incidence ratios for single primary UM, first primary and second primary UM, and compared the groups for multiple factors. RESULTS: A total of 4946 patients were included in the study; 3863 with single primary UM, 646 developed a second primary malignancy following UM, and 437 patients developed second primary UM following a previous primary malignancy. The risk of developing UM increased after leukaemia, melanoma of the skin and prostate. On the other side, the risk of developing melanoma of the skin, thyroid, renal and other eye and orbit malignancies has increased significantly after initial UM. This risk was more evident in the age group between 50 and 70 years old. Cancer-specific survival was significantly higher in UM associated with other malignancies group compared with single primary UM. CONCLUSION: Our study showed a different behaviour of the UM when associated with other tumours that exceed the known spectrum of hereditary UM. Further studies are required to dissect the genetic background of this behaviour.

Effects of empagliflozin and target-organ damage in a novel rodent model of heart failure induced by combined hypertension and diabetes.

Type 2 diabetes mellitus and hypertension are two major risk factors leading to heart failure and cardiovascular damage. Lowering blood sugar by the sodium-glucose co-transporter 2 inhibitor empagliflozin provides cardiac protection. We established a new rat model that develops both inducible diabetes and genetic hypertension and investigated the effect of empagliflozin treatment to test the hypothesis if empagliflozin will be protective in a heart failure model which is not based on a primary vascular event. The transgenic Tet29 rat model for inducible diabetes was crossed with the mRen27 hypertensive rat to create a novel model for heart failure with two stressors. The diabetic, hypertensive heart failure rat (mRen27/tetO-shIR) were treated with empagliflozin (10 mg/kg/d) or vehicle for 4 weeks. Cardiovascular alterations were monitored by advanced speckle tracking echocardiography, gene expression analysis and immunohistological staining. The novel model with increased blood pressure und higher blood sugar levels had a reduced survival compared to controls. The rats develop heart failure with reduced ejection fraction. Empagliflozin lowered blood sugar levels compared to vehicle treated animals (182.3 ± 10.4 mg/dl vs. 359.4 ± 35.8 mg/dl) but not blood pressure (135.7 ± 10.3 mmHg vs. 128.2 ± 3.8 mmHg). The cardiac function was improved in all three global strains (global longitudinal strain - 8.5 ± 0.5% vs. - 5.5 ± 0.6%, global radial strain 20.4 ± 2.7% vs. 8.8 ± 1.1%, global circumferential strain - 11.0 ± 0.7% vs. - 7.6 ± 0.8%) and by increased ejection fraction (42.8 ± 4.0% vs. 28.2 ± 3.0%). In addition, infiltration of macrophages was decreased by treatment (22.4 ± 1.7 vs. 32.3 ± 2.3 per field of view), despite mortality was not improved. Empagliflozin showed beneficial effects on cardiovascular dysfunction. In this novel rat model of combined hypertension and diabetes, the improvement in systolic and diastolic function was not secondary to a reduction in left ventricular mass or through modulation of the afterload, since blood pressure was not changed. The mRen27/tetO-shIR strain should provide utility in separating blood sugar from blood pressure-related treatment effects.

Inhibition of Ca2+ channel surface expression by mutant bestrophin-1 in RPE cells.

The BEST1 gene product bestrophin-1, a Ca2+ -dependent anion channel, interacts with CaV 1.3 Ca2+ channels in the retinal pigment epithelium (RPE). BEST1 mutations lead to Best vitelliform macular dystrophy. A common functional defect of these mutations is reduced trafficking of bestrophin-1 into the plasma membrane. We hypothesized that this defect affects the interaction partner CaV 1.3 channel affecting Ca2+ signaling and altered RPE function. Thus, we investigated the protein interaction between CaV 1.3 channels and bestrophin-1 by immunoprecipitation, CaV 1.3 activity in the presence of mutant bestrophin-1 and intracellular trafficking of the interaction partners in confluent RPE monolayers. We selected four BEST1 mutations, each representing one mutational hotspot of the disease: T6P, F80L, R218C, and F305S. Heterologously expressed L-type channels and mutant bestrophin-1 showed reduced interaction, reduced CaV 1.3 channel activity, and changes in surface expression. Transfection of polarized RPE (porcine primary cells, iPSC-RPE) that endogenously express CaV 1.3 and wild-type bestrophin-1, with mutant bestrophin-1 confirmed reduction of CaV 1.3 surface expression. For the four selected BEST1 mutations, presence of mutant bestrophin-1 led to reduced CaV 1.3 activity by modulating pore-function or decreasing surface expression. Reduced CaV 1.3 activity might open new ways to understand symptoms of Best vitelliform macular dystrophy such as reduced electro-oculogram, lipofuscin accumulation, and vision impairment.

An exploratory investigation of brain collateral circulation plasticity after cerebral ischemia in two experimental C57BL/6 mouse models.

Brain collateral circulation is an essential compensatory mechanism in response to acute brain ischemia. To study the temporal evolution of brain macro and microcollateral recruitment and their reciprocal interactions in response to different ischemic conditions, we applied a combination of complementary techniques (T2-weighted magnetic resonance imaging [MRI], time of flight [TOF] angiography [MRA], cerebral blood flow [CBF] imaging and histology) in two different mouse models. Hypoperfusion was either induced by permanent bilateral common carotid artery stenosis (BCCAS) or 60-min transient unilateral middle cerebral artery occlusion (MCAO). In both models, collateralization is a very dynamic phenomenon with a global effect affecting both hemispheres. Patency of ipsilateral posterior communicating artery (PcomA) represents the main variable survival mechanism and the main determinant of stroke lesion volume and recovery in MCAO, whereas the promptness of external carotid artery retrograde flow recruitment together with PcomA patency, critically influence survival, brain ischemic lesion volume and retinopathy in BCCAS mice. Finally, different ischemic gradients shape microcollateral density and size.

Correction to: Lack of netrin-4 alters vascular remodeling in the retina.

The article "Lack of netrin-4 alters vascular remodeling in the retina".

Angiotensin-Receptor-Associated Protein Modulates Ca2+ Signals in Photoreceptor and Mossy Fiber cells.

Fast, precise and sustained neurotransmission requires graded Ca2+ signals at the presynaptic terminal. Neurotransmitter release depends on a complex interplay of Ca2+ fluxes and Ca2+ buffering in the presynaptic terminal that is not fully understood. Here, we show that the angiotensin-receptor-associated protein (ATRAP) localizes to synaptic terminals throughout the central nervous system. In the retinal photoreceptor synapse and the cerebellar mossy fiber-granule cell synapse, we find that ATRAP is involved in the generation of depolarization-evoked synaptic Ca2+ transients. Compared to wild type, Ca2+ imaging in acutely isolated preparations of the retina and the cerebellum from ATRAP knockout mice reveals a significant reduction of the sarcoendoplasmic reticulum (SR) Ca2+-ATPase (SERCA) activity. Thus, in addition to its conventional role in angiotensin signaling, ATRAP also modulates presynaptic Ca2+ signaling within the central nervous system.

Systemic ß adrenergic stimulation/ sympathetic nerve system stimulation influences intraocular RAS through cAMP in the RPE.

Several lines of evidence support the existence of a renin-angiotensin system (RAS) in the retina that is separated from the blood stream by the retinal pigment epithelium (RPE). Under physiological conditions, increased activity of intraretinal RAS regulates neuronal activity of the retina but patho-physiologically participates in retinal degeneration such as hypertensive or diabetic retinopathy. Interestingly, the RPE appears to be a modulator of intraretinal RAS in response to changes in systemic RAS. As increased systemic RAS activity is associated with increased sympathetic tonus, we investigated whether systemic ß-adrenergic stimulation of the RPE also modulates renin expression in the RPE. In vivo, the mouse RPE expresses the ß-adrenergic receptor subtypes 1 and 2. Staining of retina sagittal sections showed tyrosine hydroxylase positive nerve endings in the choroid indicating adrenaline/noradrenaline production sites in close proximity to the RPE. Systemic infusion of isoproterenol increased renin expression in the RPE but not in the retina. This increase was sensitive to concomitant systemic application of the angiotensin-2 receptor-type-1 blocker losartan. In vitro analysis of renin gene expression using polarized porcine RPE showed that the activity of the renin promoter can be increased by cAMP stimulation (IBMX/forskolin) but was not influenced by angiotensin-2. Thus, with the identification of the ß-adrenergic system we added a new regulator of the retinal RAS with relevance for retinal function and pathology. Furthermore, it appears that the RPE is not only a close interaction partner of the photoreceptors but also a regulator or retinal activity in general.