Successful control of menstrual cycle-related exacerbation of inflammatory arthritis with GnRH agonist with add-back therapy in a patient with rheumatoid arthritis.

Patients with rheumatoid arthritis may demonstrate fluctuations in arthritis symptoms associated with the menstrual cycle. This is the first case report of successful control of menstrual cycle-related exacerbation of rheumatoid arthritis with a gonadotropin-releasing hormone agonist and add-back therapy. A 49-year-old premenopausal woman experienced recurrent severe arthritis flares despite aggressive immunotherapy. Her arthritis symptoms started 10 days before her menstruation and spontaneously resolved after the initiation of menstruation. We chose a gonadotropin-releasing hormone agonist with percutaneous estradiol gel to prevent a hypoestrogenic state and a levonorgestrel-releasing intrauterine system to facilitate uterine protection by estrogen. Thereafter, her symptoms significantly improved without experiencing major flares. In addition, she did not demonstrate any menopausal symptoms. This case highlights that rheumatoid arthritis disease activity may be associated with the menstrual cycle, and hormonal therapy may be beneficial as an adjunct therapy for controlling premenstrual exacerbation of rheumatoid arthritis.

Telomeres and a repeat-rich chromosome encode effector gene clusters in plant pathogenic Colletotrichum fungi.

Members of the Colletotrichum gloeosporioides species complex are causal agents of anthracnose in many commercially important plants. Closely related strains have different levels of pathogenicity on hosts despite their close phylogenetic relationship. To gain insight into the genetics underlying these differences, we generated and annotated whole-genome assemblies of multiple isolates of C. fructicola (Cf) and C. siamense (Cs), as well as three previously unsequenced species, C. aenigma (Ca), C. tropicale and C. viniferum with different pathogenicity on strawberry. Based on comparative genomics, we identified accessory regions with a high degree of conservation in strawberry-pathogenic Cf, Cs and Ca strains. These regions encode homologs of pathogenicity-related genes known as effectors, organized in syntenic gene clusters, with copy number variations in different strains of Cf, Cs and Ca. Analysis of highly contiguous assemblies of Cf, Cs and Ca revealed the association of related accessory effector gene clusters with telomeres and repeat-rich chromosomes and provided evidence of exchange between these two genomic compartments. In addition, expression analysis indicated that orthologues in syntenic gene clusters showed a tendency for correlated gene expression during infection. These data provide insight into mechanisms by which Colletotrichum genomes evolve, acquire and organize effectors.

Molecular mechanisms underlying selective synapse formation of vertebrate retinal photoreceptor cells.

In vertebrate central nervous systems (CNSs), highly diverse neurons are selectively connected via synapses, which are essential for building an intricate neural network. The vertebrate retina is part of the CNS and is comprised of a distinct laminar organization, which serves as a good model system to study developmental synapse formation mechanisms. In the retina outer plexiform layer, rods and cones, two types of photoreceptor cells, elaborate selective synaptic contacts with ON- and/or OFF-bipolar cell terminals as well as with horizontal cell terminals. In the mouse retina, three photoreceptor subtypes and at least 15 bipolar subtypes exist. Previous and recent studies have significantly progressed our understanding of how selective synapse formation, between specific subtypes of photoreceptor and bipolar cells, is designed at the molecular level. In the ON pathway, photoreceptor-derived secreted and transmembrane proteins directly interact in trans with the GRM6 (mGluR6) complex, which is localized to ON-bipolar cell dendritic terminals, leading to selective synapse formation. Here, we review our current understanding of the key factors and mechanisms underlying selective synapse formation of photoreceptor cells with bipolar and horizontal cells in the retina. In addition, we describe how defects/mutations of the molecules involved in photoreceptor synapse formation are associated with human retinal diseases and visual disorders.

Samd7 is a cell type-specific PRC1 component essential for establishing retinal rod photoreceptor identity.

Precise transcriptional regulation controlled by a transcription factor network is known to be crucial for establishing correct neuronal cell identities and functions in the CNS. In the retina, the expression of various cone and rod photoreceptor cell genes is regulated by multiple transcription factors; however, the role of epigenetic regulation in photoreceptor cell gene expression has been poorly understood. Here, we found that Samd7, a rod-enriched sterile alpha domain (SAM) domain protein, is essential for silencing nonrod gene expression through H3K27me3 regulation in rod photoreceptor cells. Samd7-null mutant mice showed ectopic expression of nonrod genes including S-opsin in rod photoreceptor cells and rod photoreceptor cell dysfunction. Samd7 physically interacts with Polyhomeotic homologs (Phc proteins), components of the Polycomb repressive complex 1 (PRC1), and colocalizes with Phc2 and Ring1B in Polycomb bodies. ChIP assays showed a significant decrease of H3K27me3 in the genes up-regulated in the Samd7-deficient retina, showing that Samd7 deficiency causes the derepression of nonrod gene expression in rod photoreceptor cells. The current study suggests that Samd7 is a cell type-specific PRC1 component epigenetically defining rod photoreceptor cell identity.

Endoscopic pressure study integrated system reflects gastroesophageal junction competence in patients with erosive esophagitis and Barrett´s esophagus.

OBJECTIVES: The endoscopic pressure study integrated system (EPSIS) is a novel diagnostic tool for gastroesophageal reflux disease (GERD) by monitoring intragastric pressure (IGP). Evaluation of the lower esophageal sphincter (LES) function may be achieved endoscopically by utilizing this newly developed diagnostic tool. This study aimed to evaluate the association between EPSIS results and gastroesophageal reflux-related diseases, e.g., erosive esophagitis (EE) and Barrett's esophagus (BE). METHODS: This was a retrospective, single-center study. All patients who underwent EPSIS between November 2016 and July 2018 were included. EPSIS was performed during esophagogastroduodenoscopy with a dedicated electronic device and a through-the-scope catheter. The maximum IGP (IGP-max) and IGP waveform pattern (flat or uphill) were recorded with this system. Evaluation of an EE and BE was based on the Los Angeles classification and Prague classification, respectively. RESULTS: A total of 104 patients were enrolled; 29 (28%) had EE and 42 (40%) had BE. Patients with EE had lower IGP-max values (16.0 vs 18.8 mmHg, P = 0.01) and an EPSIS flat pattern was seen more frequently (82.8% vs 37.3%, P < 0.001). Similarly, patients with BE displayed a lower IGP-max (15.7 vs 19.6 mmHg, P < 0.001) and presented with an EPSIS flat pattern in a higher proportion (69% vs 37.1%, P < 0.001). These differences remained significant on multivariate analysis. CONCLUSIONS: The EPSIS, as a novel diagnostic tool, was shown to exhibit a relation with EE and BE, implying that EPSIS is a promising modality to evaluate gastroesophageal reflux-related diseases and LES function endoscopically.

Clinical outcomes of per-oral endoscopic tumor resection for submucosal tumors in the esophagus and gastric cardia.

OBJECTIVES: The clinical success of per-oral endoscopic myotomy (POEM) has led to the development of a new field of 'submucosal endoscopy'. This study aimed to evaluate the safety, efficacy, and limitations of per-oral endoscopic tumor resection (POET) in the management of submucosal tumors (SMTs) in the esophagus and the gastric cardia. METHODS: POET was performed in 47 patients from January 2011 to December 2017. The indication for POET was SMTs ≤ 30 mm in minor axis diameter. Patient and tumor characteristics (age, gender, tumor location, size, and histology), operative and clinical results of POET (procedure time and completion rate, en bloc resection rate, length of hospitalization, adverse events and tumor recurrence) were analyzed retrospectively. RESULTS: POET was successfully completed in 43 patients (91.5%) without any major adverse events (Clavien-Dindo IIIb-IV). Four patients required conversion to an open surgical procedure due to suboptimal visualization during POET. Four patients underwent piecemeal resection of their SMTs including GISTs. Median follow-up was 44 months (10-96 months), during that time, there were no incidences of tumor recurrence. Tumors that had a minor axis diameter > 30 mm or a tumor mass index (TMI) [major axis diameter (mm) × minor axis diameter (mm)] >1000 had a high likelihood of being converted to surgical resection. CONCLUSIONS: POET is a safe and effective treatment for SMTs. However, in patients where the minor axis diameter is > 30 mm or the TMI > 1000, surgical excision should be considered. Furthermore, application of POET for SMTs with malignant potential should be carefully considered to ensure optimal oncologic outcomes.

Peroral endoscopic myotomy and fundoplication: a novel NOTES procedure.

BACKGROUND: Peroral endoscopic myotomy (POEM) has become the minimally invasive endoscopic treatment for achalasia; however, gastroesophageal reflux (GER) post-POEM has been reported. A pilot study was conducted in which an endoscopic fundoplication was added to the standard POEM (POEM + F) procedure to overcome this issue. We report the technical details of POEM + F and short-term safety results. METHODS: POEM + F was performed in 21 patients. After completing myotomy, the endoscope was advanced from the submucosal tunnel into the peritoneal cavity. A partial mechanical barrier was created by retracting the anterior gastric wall at the esophagogastric junction with the use of endoclips and an endoloop. RESULTS: POEM + F was technically feasible in all cases and created a visually recognizable fundoplication. The clinical course after POEM + F was uneventful. No immediate or delayed complications occurred. CONCLUSION: POEM + F may help mitigate the post-POEM incidence of GER and serve as a minimally invasive endoscopic alternative to a laparoscopic Heller-Dor procedure. This is the largest case series of peroral natural orifice transluminal endoscopic surgery without laparoscopic assistance in the human foregut.

Loss of ift122, a Retrograde Intraflagellar Transport (IFT) Complex Component, Leads to Slow, Progressive Photoreceptor Degeneration Due to Inefficient Opsin Transport.

In the retina, aberrant opsin transport from cell bodies to outer segments leads to retinal degenerative diseases such as retinitis pigmentosa. Opsin transport is facilitated by the intraflagellar transport (IFT) system that mediates the bidirectional movement of proteins within cilia. In contrast to functions of the anterograde transport executed by IFT complex B (IFT-B), the precise functions of the retrograde transport mediated by IFT complex A (IFT-A) have not been well studied in photoreceptor cilia. Here, we analyzed developing zebrafish larvae carrying a null mutation in ift122 encoding a component of IFT-A. ift122 mutant larvae show unexpectedly mild phenotypes, compared with those of mutants defective in IFT-B. ift122 mutants exhibit a slow onset of progressive photoreceptor degeneration mainly after 7 days post-fertilization. ift122 mutant larvae also develop cystic kidney but not curly body, both of which are typically observed in various ciliary mutants. ift122 mutants display a loss of cilia in the inner ear hair cells and nasal pit epithelia. Loss of ift122 causes disorganization of outer segment discs. Ectopic accumulation of an IFT-B component, ift88, is observed in the ift122 mutant photoreceptor cilia. In addition, pulse-chase experiments using GFP-opsin fusion proteins revealed that ift122 is required for the efficient transport of opsin and the distal elongation of outer segments. These results show that IFT-A is essential for the efficient transport of outer segment proteins, including opsin, and for the survival of retinal photoreceptor cells, rendering the ift122 mutant a unique model for human retinal degenerative diseases.

Low intracellular iron increases the stability of matriptase-2.

Matriptase-2 (MT2) is a type II transmembrane serine protease that is predominantly expressed in hepatocytes. It suppresses the expression of hepatic hepcidin, an iron regulatory hormone, by cleaving membrane hemojuvelin into an inactive form. Hemojuvelin is a bone morphogenetic protein (BMP) co-receptor. Here, we report that MT2 is up-regulated under iron deprivation. In HepG2 cells stably expressing the coding sequence of the MT2 gene, TMPRSS6, incubation with apo-transferrin or the membrane-impermeable iron chelator, deferoxamine mesylate salt, was able to increase MT2 levels. This increase did not result from the inhibition of MT2 shedding from the cells. Rather, studies using a membrane-permeable iron chelator, salicylaldehyde isonicotinoyl hydrazone, revealed that depletion of cellular iron was able to decrease the degradation of MT2 independently of internalization. We found that lack of the putative endocytosis motif in its cytoplasmic domain largely abolished the sensitivity of MT2 to iron depletion. Neither acute nor chronic iron deficiency was able to alter the association of Tmprss6 mRNA with polyribosomes in the liver of rats indicating a lack of translational regulation by low iron levels. Studies in mice showed that Tmprss6 mRNA was not regulated by iron nor the BMP-mediated signaling with no evident correlation with either Bmp6 mRNA or Id1 mRNA, a target of BMP signaling. These results suggest that regulation of MT2 occurs at the level of protein degradation rather than by changes in the rate of internalization and translational or transcriptional mechanisms and that the cytoplasmic domain of MT2 is necessary for its regulation.

Intraoperative bladder visualization by indocyanine green filling and subsequent washout in endoscopic hysterectomy: ICG-Washout method.

INTRODUCTION: Despite a potential risk of bladder injury in laparoscopic hysterectomy (LH) and robot-assisted LH (RaLH), an intraoperative method for delineating the entire bladder with indocyanine green (ICG) has not been established. METHODS: We conducted a preliminary experiment using porcine bladders to verify the appropriate amount of ICG for intraoperative bladder visualization. Afterward, intraoperative bladder visualization was tried in LH and RaLH in two patients suspected of having adhesions around the bladder after previous abdominal surgery. RESULTS: Although near-infrared (NIR) fluorescence was well observed through the wall of the porcine bladder filled with ICG solution at a concentration of 0.024 mg/mL, the subsequent replacement of the ICG solution with saline made the NIR fluorescence brighter. In both patients, the bladder was successfully delineated by NIR fluorescence after filling the bladder with ICG solution and the subsequent washout with saline. CONCLUSION: The ICG-Washout method for locating the bladder by NIR fluorescence could be useful in LH and RaLH.

Hepatic stellate cell-derived delta-like homolog 1 (DLK1) protein in liver regeneration.

Hepatic stellate cells (HSCs) undergo myofibroblastic activation in liver fibrosis and regeneration. This phenotypic switch is mechanistically similar to dedifferentiation of adipocytes as such the necdin-Wnt pathway causes epigenetic repression of the master adipogenic gene Pparγ, to activate HSCs. Now we report that delta-like 1 homolog (DLK1) is expressed selectively in HSCs in the adult rodent liver and induced in liver fibrosis and regeneration. Dlk1 knockdown in activated HSCs, causes suppression of necdin and Wnt, epigenetic derepression of Pparγ, and morphologic and functional reversal to quiescent cells. Hepatic Dlk1 expression is induced 40-fold at 24 h after partial hepatectomy (PH) in mice. HSCs and hepatocytes (HCs) isolated from the regenerating liver show Dlk1 induction in both cell types. In HC and HSC co-culture, increased proliferation and Dlk1 expression by HCs from PH are abrogated with anti-DLK1 antibody (Ab). Dlk1 and Wnt10b expression by Sham HCs are increased by co-culture with PH HSCs, and these effects are abolished with anti-DLK Ab. A tail vein injection of anti-DLK1 Ab at 6 h after PH reduces early HC proliferation and liver growth, accompanied by decreased Wnt10b, nonphosphorylated ß-catenin, p-ß-catenin (Ser-552), cyclins (cyclin D and cyclin A), cyclin-dependent kinases (CDK4, and CDK1/2), p-ERK1/2, and p-AKT. In the mouse developing liver, HSC precursors and HSCs express high levels of Dlk1, concomitant with Dlk1 expression by hepatoblasts. These results suggest novel roles of HSC-derived DLK1 in activating HSCs via epigenetic Pparγ repression and participating in liver regeneration and development in a manner involving the mesenchymal-epithelial interaction.

Successful Recovery from Severe Fever with Thrombocytopenia Syndrome and Hemophagocytic Lymphohistiocytosis with Standard Treatment and a Calcium Channel Blocker of Nicardipine Hydrochloride.

A 67-year-old man was admitted to our hospital with a high fever. Laboratory tests revealed leukopenia, thrombocytopenia, liver dysfunction, rhabdomyolysis, and hyperferritinemia. He was diagnosed with severe fever with thrombocytopenia syndrome (SFTS) complicated by hemophagocytic lymphohistiocytosis and treated with steroid therapy, intravenous calcium channel blocker (CCB), and supportive care, without favipiravir. Serum levels of ferritin and soluble interleukin 2 receptor (sIL2R) were markedly elevated on Day 3 after admission and decreased thereafter, while an SFTS viral load of 6.8×104 copies/µL was detected on Day 2, increasing to 2.9×105 copies/µL on Day 6. Serum ferritin and sIL2R levels may be better indicators of mortality than the SFTS viral load, and CCBs may have a therapeutic effect.

Ascorbic acid gives different protective effects in human cells exposed to X-rays and heavy ions.

We studied the effects and mechanisms of ascorbic acid as a radiation protector. Cell survival, repair of DNA double strand breaks (DSBs), and sister chromatid exchanges (SCEs) were examined in normal human fibroblasts irradiated with X-rays and heavy ions. Post-irradiation treatment with 5mM ascorbic acid for 24 h in plateau phase (non-cycling) cells enhanced cell survival and DNA double strand break repair, and reduced SCEs after X-rays irradiation. On the other hand, only reduced SCEs were observed after heavy ion exposure such as to carbon ions. Judging from our data, it is possible that the radioprotective action of ascorbic acid would be effective in non-complex type DNA damage such as induced by X-rays. These findings provide new insight into the mechanism of DNA damage and repair produced by heavy ion irradiation.

Anti-reflux mucosal ablation (ARMA) as a new treatment for gastroesophageal reflux refractory to proton pump inhibitors: a pilot study.

Background The incidence of proton pump inhibitor (PPI)-refractory gastroesophageal reflux disease (GERD) has been increasing. While surgical intervention with Laparoscopic Nissen Fundoplication remains the gold standard, less invasive anti-reflux interventions are desired. We have developed a minimally invasive anti-reflux mucosal ablation (ARMA) treatment. Herein, we report its technical details and describe its feasibility, safety, and efficacy in PPI-refractory GERD. Methods We conducted a prospective single-center single-arm interventional trial evaluating the outcome of ARMA in 12 patients with PPI-refractory GERD. GERD-Health Related Quality of Life Questionnaire (GERD-HRQL) evaluation, Frequency Scale for the Symptoms of GERD (FSSG) assessment, and impedance-pH monitoring were performed at baseline and at 2 months post-ARMA. Results A total of 12 patients underwent ARMA with a median follow-up duration of 9 months (range: 6 - 14 months). Median GERD-HRQL score significantly improved from 30.5 to 12 ( P  = 0.002); median FSSG score significantly improved from 25 to 10.5 ( P  = 0.002), and median DeMeester score decreased from 33.5 to 2.8 ( P  = 0.049) at 2 months follow-up. No immediate complications were observed. Conclusion Our pilot study has shown that ARMA, a new endoscopic treatment for PPI-refractory GERD, is simple, safe, and improves GERD-related symptoms and objective acid reflux parameters.

Establishment of a selection marker recycling system for sequential transformation of the plant-pathogenic fungus Colletotrichum orbiculare.

Genome sequencing of pathogenic fungi has revealed the presence of various effectors that aid pathogen invasion by the manipulation of plant immunity. Effectors are often individually dispensable because of duplication and functional redundancy as a result of the arms race between host plants and pathogens. To study effectors that have functional redundancy, multiple gene disruption is often required. However, the number of selection markers that can be used for gene targeting is limited. Here, we established a marker recycling system that allows the use of the same selection marker in successive transformations in the model fungal pathogen Colletotrichum orbiculare, a causal agent of anthracnose disease in plants belonging to the Cucurbitaceae. We identified two C. orbiculare homologues of yeast URA3/pyrG, designated as URA3A and URA3B, which can be used as selection markers on medium with no uridine. The gene can then be removed from the genome via homologous recombination when the fungus is grown in the presence of 5-fluoroorotic acid (5-FOA), a chemical that is converted into a toxin by URA3 activity. The ura3a/b double mutants showed auxotrophy for uridine and insensitivity to 5-FOA. Using the ura3a/b mutants, transformation with the URA3B marker and its removal were successfully applied to disrupt the virulence-related gene, PKS1. The pks1 mutants showed a reduction in virulence, demonstrating that the method can be used to study virulence-related genes in C. orbiculare. The establishment of a URA3-based marker recycling system in plant-pathogenic fungi enables the genetic analysis of multiple genes that have redundant functions, including effector genes.

2007-2019: a "Third"-Space Odyssey in the Endoscopic Management of Gastrointestinal Tract Diseases.

PURPOSE OF REVIEW: The main scope of this review article is to introduce readers to the innovative field of third-space endoscopy and offer a closer look at its history, milestones, and procedure spectrum while discussing ongoing and future challenges arising from its increasing adoption worldwide. RECENT FINDINGS: Over the past few years, third-space endoscopy has been utilized in various diagnostic and interventional procedures performed throughout the gastrointestinal tract: obliteration of Zenker's diverticulum, myotomy for achalasia, gastroparesis or Hirschsprung's disease, biopsy or removal of subepithelial tumors, stricture management, post-per-oral endoscopic myotomy endoscopic fundoplication, and mediastino-, thoraco-, and peritoneoscopy. Third-space endoscopic interventions have revolutionized the management of esophageal motility disorders, gastroparesis, and gastrointestinal tract subepithelial tumors. Despite the high efficacy and safety of such interventions, some common (e.g., the high level of necessary endoscopic skill) and unique for each procedure (e.g., post-procedure gastroesophageal reflux or poor outcomes in patient subgroups) challenges still remain. Through a dedicated endoscopic training, a rigorous pre-procedure patient evaluation and selection, and the application of modified or new techniques, challenges can be overcome thus establishing existing procedures and paving the way for additional breakthroughs in the field of third-space endoscopy.

Total synthesis of (+/-)-murrayazoline.

The total synthesis of (+/-)-murrayazoline (1) is described. The characteristic hexa-heterocyclic structure of 1 was constructed by a combination of the intramolecular Friedel-Crafts-type Michael addition and Pd-catalyzed C-O coupling reactions. The N-substituted carbazole component was synthesized in one pot by the double N-arylation of a sterically hindered amine with a dibromobiphenyl derivative.

Comparison of endometriotic cysts and ovarian cancer in association with endometriotic cysts.

OBJECTIVE: The aim of this study was to clarify the clinical, laboratory, and imaging findings of ovarian cancer in association with endometriotic cysts by detailed comparison of the findings of benign and malignant tumors. METHODS AND MATERIALS: This was a retrospective study of 138 women who had an operation for ovarian tumors at the Department of Obstetrics and Gynecology of Kochi Health Sciences Center between September 1, 2011, and July 30, 2015. The ovarian tumors were divided into two groups: the benign group (endometriotic cysts) and the malignant group (ovarian cancer in association with endometriotic cysts). RESULTS: Of the 138 patients, 28 had malignant disease, and 110 had benign endometriotic cysts. Patients in the malignant group were significantly older than patients in the benign group. The mean maximum tumor diameter was also significantly larger for the malignant tumors. Unilocular-solid and multilocular-solid type tumors were present in 25.0% and 75.0% of malignant tumors, and in 9.1% and 19.1% of benign tumors, respectively. The mean maximum solid component diameter and height were significantly larger in the malignant tumors than in the benign tumors. The solid components were present on the abdominal side of the cyst wall in 12.5% of benign tumors and in 51.9% of malignant tumors. CONCLUSION: In elderly patients, the presence of large solid components in large endometriotic cysts, especially the abdominal side of the cyst wall, might suggest malignancy. MICRO ABSTRACT: The aim of this study was to clarify the findings of ovarian cancer in association with endometriotic cysts by detailed comparison of the findings of benign and malignant tumors. The presence of solid components in large endometriotic cysts, especially the abdominal side of the cyst wall, might suggest malignancy.

Transsynaptic Binding of Orphan Receptor GPR179 to Dystroglycan-Pikachurin Complex Is Essential for the Synaptic Organization of Photoreceptors.

Establishing synaptic contacts between neurons is paramount for nervous system function. This process involves transsynaptic interactions between a host of cell adhesion molecules that act in cooperation with the proteins of the extracellular matrix to specify unique physiological properties of individual synaptic connections. However, understanding of the molecular mechanisms that generate functional diversity in an input-specific fashion is limited. In this study, we identify that major components of the extracellular matrix proteins present in the synaptic cleft-members of the heparan sulfate proteoglycan (HSPG) family-associate with the GPR158/179 group of orphan receptors. Using the mammalian retina as a model system, we demonstrate that the HSPG member Pikachurin, released by photoreceptors, recruits a key post-synaptic signaling complex of downstream ON-bipolar neurons in coordination with the pre-synaptic dystroglycan glycoprotein complex. We further demonstrate that this transsynaptic assembly plays an essential role in synaptic transmission of photoreceptor signals.

Lrit1, a Retinal Transmembrane Protein, Regulates Selective Synapse Formation in Cone Photoreceptor Cells and Visual Acuity.

In the vertebrate retina, cone photoreceptors play crucial roles in photopic vision by transmitting light-evoked signals to ON- and/or OFF-bipolar cells. However, the mechanisms underlying selective synapse formation in the cone photoreceptor pathway remain poorly understood. Here, we found that Lrit1, a leucine-rich transmembrane protein, localizes to the photoreceptor synaptic terminal and regulates the synaptic connection between cone photoreceptors and cone ON-bipolar cells. Lrit1-deficient retinas exhibit an aberrant morphology of cone photoreceptor pedicles, as well as an impairment of signal transmission from cone photoreceptors to cone ON-bipolar cells. Furthermore, we demonstrated that Lrit1 interacts with Frmpd2, a photoreceptor scaffold protein, and with mGluR6, an ON-bipolar cell-specific glutamate receptor. Additionally, Lrit1-null mice showed visual acuity impairments in their optokinetic responses. These results suggest that the Frmpd2-Lrit1-mGluR6 axis regulates selective synapse formation in cone photoreceptors and is essential for normal visual function.