The binding of LARP6 and DNAAF6 in biomolecular condensates influences ciliogenesis of multiciliated cells.

Motile cilia on the cell surface produce fluid flows in the body and abnormalities in motile cilia cause primary ciliary dyskinesia. Dynein axonemal assembly factor 6 (DNAAF6), a causative gene of primary ciliary dyskinesia, was isolated as an interacting protein with La ribonucleoprotein 6 (LARP6) that regulates ciliogenesis in multiciliated cells (MCCs). In MCCs of Xenopus embryos, LARP6 and DNAAF6 were colocalized in biomolecular condensates termed dynein axonemal particles and synergized to control ciliogenesis. Moreover, tubulin alpha 1c-like mRNA encoding α-tubulin protein, that is a major component of ciliary axoneme, was identified as a target mRNA regulated by binding LARP6. While DNAAF6 was necessary for high α-tubulin protein expression near the apical side of Xenopus MCCs during ciliogenesis, its mutant, which abolishes binding with LARP6, was unable to restore the expression of α-tubulin protein near the apical side of MCCs in Xenopus DNAAF6 morphant. These results indicated that the binding of LARP6 and DNAAF6 in dynein axonemal particles regulates highly expressed α-tubulin protein near the apical side of Xenopus MCCs during ciliogenesis.

Abnormal accumulation of OFD1 in endometrial cancer with poor prognosis inhibits ciliogenesis.

The aim of the present study was to examine primary cilia in endometrial tissue during the menstrual cycle and to clarify their morphological changes with different grades of endometrial cancer. Images of fluorescence immunostaining taken by confocal microscopy were used to count the number of primary cilia in normal endometrium and endometrioid carcinoma Grade 1 and Grade 3 specimens. To examine the association between autophagy and ciliogenesis in endometrioid carcinoma, the expression of p62/Sequestosome-1, a selective substrate for autophagy, and oral-facial-digital syndrome 1 protein (OFD1), a protein associated with ciliogenesis, were examined using images of fluorescence immunostaining taken by confocal microscopy. The level of p62 expression was confirmed by western blotting. In proliferative and secretory endometrial stromal cells, the percentage of cells that were ciliated was 7.2 and 32.7% (95% confidence interval=21.61-39.79; P<0.01), and the length of the primary cilia was 1.24 µm and 2.34 µm (0.92-1.26; P<0.01), respectively. In stromal cells of endometrioid carcinoma Grade 1 and Grade 3, the percentage of ciliated cells was 13.5 and 2.9% (7.89-15.05; P<0.001), and the length of the primary cilia was 2.02 and 1.14 µm (0.76-0.99; P<0.001), respectively. In both normal menstrual cycle tissue and endometrial carcinomas, the percentage of primary cilia was lower and their length was shorter in tissues with higher proliferative potential. The expression of OFD1 was significantly higher in Grade 3 compared with Grade 1 as indicated by quantifying the intensity of the fluorescence images (133-12248; P=0.046). To the best of our knowledge, this is the first study concerning the distribution of primary cilia in normal endometrium and endometrial cancer tissues. Overall, fewer ciliated cells in the highly malignant endometrial cancer tissues may be associated not only to the proliferation of cancer cells, but also to the excessive accumulation of OFD1 due to dysfunctional autophagy.

Ciliary signaling in stem cells in health and disease: Hedgehog pathway and beyond.

The primary cilium is a hair-like sensory compartment that protrudes from the cellular surface. The primary cilium is enriched in a variety of signaling molecules that regulate cellular activities. Stem cells have primary cilia. They reside in a specialized environment, called the stem cell niche. This niche contains a variety of secreted factors, and some of their receptors are localized in the primary cilia of stem cells. Here, we summarize the current understanding of the function of cilia in compartmentalized signaling in stem cells. We describe how ciliary signaling regulates stem cells and progenitor cells during development, tissue homeostasis and tumorigenesis. We summarize our understanding of cilia regulated signaling -primary involving the hedgehog pathway- in stem cells in diverse settings that include neuroepithelial cells, radial glia, cerebellar granule neuron precursors, hematopoietic stem cells, hair follicle stem cells, bone marrow mesenchymal stem cells and mammary gland stem cells. Overall, our review highlights a variety of roles that ciliary signaling plays in regulating stem cells throughout life.

Hospital Evacuation Implications After the 2016 Kumamoto Earthquake.

During the 2016 Kumamoto earthquake, 10 hospitals took responsibility for complete evacuation, in what has become regarded as one of the largest evacuations of patients in 1 seismic disaster. We aimed to examine the reasons for evacuation and to assess hospital vulnerability as well as preparedness for the earthquake. A multidisciplinary team conducted semi-structured interviews with the hospitals 6 months after the earthquake. The primary reasons for the decision to evacuate hospitals were categorized into 3: 1) Concern for structural safety (4 facilities), 2) Damage to the facility water system (7 facilities), and 3) Cessation of regional water supply (5 facilities).All hospitals decided on immediate evacuation within 30 hours and could not wait for structural engineers to inspect the affected buildings. Damage to sprinklers or water facilities caused severe water shortages and flood, thus requiring weeks to resume inpatient care. The earthquake revealed the vulnerability of rapid building-inspection systems, aging buildings, and water infrastructure.

Abnormal ciliogenesis in decidual stromal cells in recurrent miscarriage.

Primary cilia regulate cellular signaling and are involved in both sensing and transducing extracellular stimuli. A recent study of patients with recurrent miscarriage (RM) identified mutations affecting DYNC2H1, which were involved in ciliary biogenesis. However, there has been no study concerning primary cilia in the decidua. We compared the number and the length of primary cilia in the decidua of 15 patients with unexplained RM with those of 7 pregnant controls who underwent an artificial termination of pregnancy. Immunohistochemistry was performed using antibodies against primary cilia, extravillous trophoblasts (EVTs), macrophages, uterine Natural Killer (uNK) cells, decidual stromal cells, and the activation of TGF-ß and CREB signaling in the decidua of early pregnancy was studied. The density of decidual stromal cells, but not EVTs, macrophages or uNK cells, was found to be significantly higher in the decidua of patients compared to controls. The percentage of ciliated decidual stromal cells was significantly decreased in patients. There was no difference in the primary ciliary length. Regarding TGF-ß signaling, p-Smad2 in these cells was diminished significantly in patients, and most of the TGF-ß-activated decidual stromal cells of both patients and controls had primary cilia. No difference in the activation of CREB was found. Abnormal primary cilia on decidual stromal cells may be one of the explanatory factors for unknown RM. The inactivation of TGF-ß signaling may lead to abnormal ciliogenesis in the decidua.

Verruciform xanthoma accompanying a cystic growth: A case report.

Verruciform xanthoma, an uncommon, benign lesion with characteristic histopathological features, usually develops on the oral mucosa or genital area. We present an unusual case of verruciform xanthoma observed on the inguinal skin of a 52-year-old healthy man along with an underlying cystic component. The superficial lesion was a pedunculated nodule with a fissured surface and an 18-mm mound-like pigmented tumor underneath it. The histopathologically deep lesion was continuously attached to the superficial lesion. It was composed of fistula or sinus-like spaces and covered with acanthotic epithelium. The epidermis and upper dermis of both lesions showed identical histopathological findings: varying degrees of acanthosis, elongation of rete ridges, eosinophilic parakeratotic layer extending toward the dermis, and densely infiltrating foam cells confined to the papillary layer of the dermis. This finding of a cystic component in the deep dermis expands the histopathologic features of verruciform xanthoma.

Calcineurin regulates cyclin D1 stability through dephosphorylation at T286.

The Calcineurin/NFAT (nuclear factor of activated T cells) pathway plays an essential role in the tumorigenic and metastatic properties in breast cancer. The molecular mechanism of the antiproliferative effect of calcineurin inhibition, however, is poorly understood. We found that calcineurin inhibition delayed cell cycle progression at G1/S, and promoted cyclin D1 degradation by inhibiting dephosphorylation at T286. Importantly, overexpression of cyclin D1 partially rescued delayed G1/S progression, thereby revealing cyclin D1 as a key factor downstream of calcineurin inhibition. Cyclin D1 upregulation is observed in human invasive breast cancers, and our findings indicate that dysregulation of T286 phosphorylation could play a role in this phenomenon. We therefore propose that targeting site specific phosphorylation of cyclin D1 could be a potential strategy for clinical intervention of invasive breast cancer.

Biallelic KARS pathogenic variants cause an early-onset progressive leukodystrophy.

The leukodystrophies cause severe neurodevelopmental defects from birth and follow an incurable and progressive course that often leads to premature death. It has recently been reported that abnormalities in aminoacyl t-RNA synthetase (ARS) genes are linked to various unique leukodystrophies and leukoencephalopathies. Aminoacyl t-RNA synthetase proteins are fundamentally known as the first enzymes of translation, catalysing the conjugation of amino acids to cognate tRNAs for protein synthesis. It is known that certain aminoacyl t-RNA synthetase have multiple non-canonical roles in both transcription and translation, and their disruption results in varied and complicated phenotypes. We clinically and genetically studied seven patients (six male and one female; aged 2 to 12 years) from five unrelated families who all showed the same phenotypes of severe developmental delay or arrest (7/7), hypotonia (6/7), deafness (7/7) and inability to speak (6/7). The subjects further developed intractable epilepsy (7/7) and nystagmus (6/6) with increasing age. They demonstrated characteristic laboratory data, including increased lactate and/or pyruvate levels (7/7), and imaging findings (7/7), including calcification and abnormal signals in the white matter and pathological involvement (2/2) of the corticospinal tracts. Through whole-exome sequencing, we discovered genetic abnormalities in lysyl-tRNA synthetase (KARS). All patients harboured the variant [c.1786C>T, p.Leu596Phe] KARS isoform 1 ([c.1702C>T, p.Leu568Phe] of KARS isoform 2) either in the homozygous state or compound heterozygous state with the following KARS variants, [c.879+1G>A; c.1786C>T, p.Glu252_Glu293del; p.Leu596Phe] ([c.795+1G>A; c.1702C>T, p.Glu224_Glu255del; p.Leu568Phe]) and [c.650G>A; c.1786C>T, p.Gly217Asp; p.Leu596Phe] ([c.566G>A; c.1702C>T, p.Gly189Asp; p.Leu568Phe]). Moreover, similarly disrupted lysyl-tRNA synthetase (LysRS) proteins showed reduced enzymatic activities and abnormal CNSs in Xenopus embryos. Additionally, LysRS acts as a non-canonical inducer of the immune response and has transcriptional activity. We speculated that the complex functions of the abnormal LysRS proteins led to the severe phenotypes in our patients. These KARS pathological variants are novel, including the variant [c.1786C>T; p.Leu596Phe] (c.1702C>T; p.Leu568Phe) shared by all patients in the homozygous or compound-heterozygous state. This common position may play an important role in the development of severe progressive leukodystrophy. Further research is warranted to further elucidate this relationship and to investigate how specific mutated LysRS proteins function to understand the broad spectrum of KARS-related diseases.

Clinical features of stroke mimics in the emergency department.

AIM: To clarify the features of stroke mimics. METHODS: We retrospectively investigated stroke mimic cases among the suspected stroke cases examined at our emergency department, over the past 9 years, during the tissue-type plasminogen activator treatment time window. RESULTS: Of 1,557 suspected acute stroke cases examined at the emergency department, 137 (8.8%) were stroke mimics. The most common causes were symptomatic epilepsy (28 cases, 20.4%), neuropathy-like symptoms (21 cases, 15.3%), and hypoglycemia (15 cases, 10.9%). Outcomes were survival to hospital discharge for 91.2% and death for 8.8% of the cases. Clinical results were significantly different between stroke mimics and the stroke group for low systolic blood pressure, low National Institutes of Health Stroke Scale score on initial treatment, history of diabetes, and no history of arrhythmia. On multivariate analysis, distinguishing factors for stroke mimics include systolic blood pressure ≤ 140 mmHg, National Institutes of Health Stroke Scale score ≤ 5 points, history of diabetes, and no history of arrhythmia. CONCLUSIONS: Frequency of stroke mimics in cases of acute stroke suspected cases is 8.8%, and the most common cause is epilepsy. In order to distinguish stroke mimics, it is useful to understand common diseases presenting as stroke mimics and evaluate clinical features different from stroke by medical interview or nerve examination.

La-related protein 6 controls ciliated cell differentiation.

BACKGROUND: La-related protein 6 (LARP6) is an evolutionally conserved RNA-binding protein. Vertebrate LARP6 binds the 5' stem-loop found in mRNAs encoding type I collagen to regulate their translation, but other target mRNAs and additional functions for LARP6 are unknown. The aim of this study was to elucidate an additional function of LARP6 and to evaluate the importance of its function during development. METHODS: To uncover the role of LARP6 in development, we utilized Morpholino Oligos to deplete LARP6 protein in Xenopus embryos. Then, embryonic phenotypes and ciliary structures of LAPR6 morphants were examined. To identify the molecular mechanism underlying ciliogenesis regulated by LARP6, we tested the expression level of cilia-related genes, which play important roles in ciliogenesis, by RT-PCR or whole mount in situ hybridization (WISH). RESULTS: We knocked down LARP6 in Xenopus embryos and found neural tube closure defects. LARP6 mutant, which compromises the collagen synthesis, could rescue these defects. Neural tube closure defects are coincident with lack of cilia, antenna-like cellular organelles with motility- or sensory-related functions, in the neural tube. The absence of cilia at the epidermis was also observed in LARP6 morphants, and this defect was due to the absence of basal bodies which are formed from centrioles and required for ciliary assembly. In the process of multi-ciliated cell (MCC) differentiation, mcidas, which activates the transcription of genes required for centriole formation during ciliogenesis, could partially restore MCCs in LARP6 morphants. In addition, LARP6 likely controls the expression of mcidas in a Notch-independent manner. CONCLUSIONS: La-related protein 6 is involved in ciliated cell differentiation during development by controlling the expression of cilia-related genes including mcidas. This LARP6 function involves a mechanism that is distinct from its established role in binding to collagen mRNAs and regulating their translation.

[WT1 Class I Peptide/WT1 Class II Peptide Pulsed Dendritic Cell Therapy Efficacy in 60 Patients with a Wide Range of Advanced Cancers].

We assessed the efficacy of WT1 class I peptide and WT1 class II peptide pulsed dendritic cell(DC)therapy for a wide range of advanced cancers. This retrospective study included 60 advanced cancer patients who were vaccinated 5times or more in this clinic between September 2013 and December 2015. The clinical response was examined. This treatment was approved by the ethics panel at this institution. Sixty patients were injected an average of 6.15times with dendritic cells(DCs) (2.6×10 / 7 cells/injection). Overall, 55of 60(92%)patients achieved a clinical benefit per the RECIST v1.1 criteria. The median survival time(MST)from diagnosis was 26.9 months, and the MST from the first admission at this institution was 12.2 months. Complete response(CR)was achieved in 5patients(9.1%), partial response(PR)in 12(22%), and stable disease(SD) in 21(38%), with confirmed progressive disease(PD)in 17(31%). In 11 cases of pancreatic cancer, the response(RR)and disease control rates(DCR)were 27%and 55%,respectively. In 8 cases of colorectal cancer, the rates were 25% and 75%; in 7 cases of lung cancer, the rates were 29% and 43%; in 7 cases of gastric cancer, the rates were 71% and 86%; in 22 other types, the rates were 23% and 74%. These results demonstrated the potential clinical efficacy of DC-based immunotherapy.

The Superior-Edge-of-the-Knee Incision Method in Lymphaticovenular Anastomosis for Lower Extremity Lymphedema.

BACKGROUND: Lymphatic vessel diameter and lymph flow are important for accurate anastomosis and effective lymph-to-venous flow in lymphaticovenular anastomosis. The authors developed a reliable method, the superioredge-of-the-knee incision method, for detecting and making the best use of high-flow lymphatic vessels in the distal medial thigh between the deep and superficial fascia, where movement of the knee, combined with compression between these fascial layers, theoretically results in upward propulsion of lymphatic fluid. METHODS: Intraoperative detection of large lymphatic vessels and of venous reflux and postoperative lymphedematous volume reduction were compared between 15 patients in whom lymphaticovenular anastomoses with the superior-edge-of-the-knee incision method were undergone and 15 in whom conventional lymphaticovenular anastomoses were undergone. RESULTS: Lymphaticovenular anastomosis at the thigh yielded 30 anastomoses in the superior-edge-of-the-knee incision group and 32 anastomoses in the non-superior-edge-of-the-knee incision group. Large lymphatic vessels were more frequently found in the superior-edge-of-the-knee incision group than in the non-superior-edge-of-the-knee incision group (60.0 percent versus 18.8 percent; p = 0.002). Venous reflux occurred less frequently in the superior-edge-of-the-knee incision group than in the non-superior-edge-of-the-knee incision group (10.0 percent versus 65.6 percent; p < 0.001). Reduction of the lower extremity lymphedema index was significantly greater in the superior-edge-of-the-knee incision group than in the non-superior-edge-of-the-knee incision group (24.427 ± 12.400 versus 0.032 ± 20.535; p < 0.001). CONCLUSION: The superior-edge-of-the-knee incision method facilitates detection and use of large, high-flow lymphatic vessels in the distal medial thigh, both of which are important for optimum therapeutic effects in patients with lower extremity lymphedema. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

TGF-ß Signaling Regulates the Differentiation of Motile Cilia.

The cilium is a small cellular organelle with motility- and/or sensory-related functions that plays a crucial role during developmental and homeostatic processes. Although many molecules or signal transduction pathways that control cilia assembly have been reported, the mechanisms of ciliary length control have remained enigmatic. Here, we report that Smad2-dependent transforming growth factor ß (TGF-ß) signaling impacts the length of motile cilia at the Xenopus left-right (LR) organizer, the gastrocoel roof plate (GRP), as well as at the neural tube and the epidermis. Blocking TGF-ß signaling resulted in the absence of the transition zone protein B9D1/MSKR-1 from cilia in multi-ciliated cells (MCCs) of the epidermis. Interestingly, this TGF-ß activity is not mediated by Mcidas, Foxj1, and RFX2, the known major regulators of ciliogenesis. These data indicate that TGF-ß signaling is crucial for the function of the transition zone, which in turn may affect the regulation of cilia length.

[Efficacy of WT1 peptide-/MUC-1 peptide-pulsed dendritic cell therapy in 313 patients with a wide range of cancers].

We assessed the efficacy of Wilms' tumor protein-1(WT1)peptide and/or mucin 1(MUC-1)peptide-pulsed dendritic cell(DC)therapy for a wide range of advanced cancers.This retrospective study included 313 patients with advanced cancer who were vaccinated ≥5 times in our clinic between May 2009 and October 2013.T he clinical response was evaluated.This treatment was approved by the ethics panel of our institution.A total of 313 patients were injected an average of 6.0 times with DCs(2.4×10 / 7 cells/injection).Overall, 292 of the 313(93%)patients obtained clinical benefit according to the Response Evaluation Criteria in Solid Tumors(RECIST), version 1.1. The median survival time(MST)from diagnosis and from first being admitted to this institution was 28.4 months and 13.2 months, respectively. Complete response(CR)was achieved in 21 patients(7.2%).Partial response(PR)was achieved in 69 patients(24%).Stable disease(SD)was observed in 107 patients(37%), and progressive disease(PD)was observed in 95 patients(33%).The response rate(RR)and disease control rate(DCR)for each type of cancer were as follows: colorectal cancer(56 patients), 25%and 45%, respectively; lung cancer(39 patients), 31% and 82%, respectively; pancreatic cancer(36 patients), 22% and 64%, respectively; gastric cancer( 34 patients), 32% and 74%; breast cancer(20 patients), 15% and 75%, respectively; ovarian cancer(16 patients), 19% and 50%, respectively; esophageal cancer(15 patients), 20% and 73%, respectively; and others(76 patients), 38% and 67%.These results demonstrated the potential clinical effectiveness of DC-based immunotherapy.

RFX7 is required for the formation of cilia in the neural tube.

Regulatory Factor X (RFX) transcription factors are important for development and are likely involved in the pathogenesis of serious human diseases including ciliopathies. While seven RFX genes have been identified in vertebrates and several RFX transcription factors have been reported to be regulators of ciliogenesis, the role of RFX7 in development including ciliogenesis is not known. Here we show that RFX7 in Xenopus laevis is expressed in the neural tube, eye, otic vesicles, and somites. Knockdown of RFX7 in Xenopus embryos resulted in a defect of ciliogenesis in the neural tube and failure of neural tube closure. RFX7 controlled the formation of cilia by regulating the expression of RFX4 gene, which has been reported to be required for ciliogenesis in the neural tube. Moreover, ectopic expression of Foxj1, which is a master regulator of motile cilia formation, suppressed the expression of RFX4 but not RFX7. Taken together, RFX7 plays an important role in the process of neural tube closure at the top of the molecular cascade which controls ciliogenesis in the neural tube.

A potential molecular pathogenesis of cardiac/laterality defects in Oculo-Facio-Cardio-Dental syndrome.

Pitx2 is the last effector of the left-right (LR) cascade known to date and plays a crucial role in the patterning of LR asymmetry. In Xenopus embryos, the expression of Pitx2 gene in the left lateral plate mesoderm (LPM) is directly regulated by Xnr1 signaling, which is mediated by Smads and FoxH1. Previous studies suggest that the suppression of Pitx2 gene in the left LPM is a potential cause of cardiac/laterality defects in Oculo-Facio-Cardio-Dental (OFCD) syndrome, which is known to be caused by mutations in BCL6 co-repressor (BCOR) gene. Recently, our work has revealed that the BCL6/BCOR complex blocks Notch-dependent transcriptional activity to protect the expression of Pitx2 in the left LPM from the inhibitory activity of Notch signaling. These studies indicated that uncontrolled Notch activity in the left LPM caused by dysfunction of BCOR may result in cardiac/laterality defects of OFCD syndrome. However, this Notch-dependent inhibitory mechanism of Pitx2 gene transcription still remains unknown. Here we report that transcriptional repressor ESR1, which acts downstream of Notch signaling, inhibits the expression of Pitx2 gene by binding to a left side-specific enhancer (ASE) region in Pitx2 gene and recruiting histone deacetylase 1 (HDAC1) to this region. Once HDAC1 is tethered, histone acetyltransferase p300 is no longer recruited to the Xnr1-dependent transcriptional complex on the ASE region, leading to the suppression of Pitx2 gene in the left LPM. The study presented here uncovers the regulatory mechanism of Pitx2 gene transcription which may contribute to an understanding of pathogenesis of OFCD syndrome.

[Prediction of WT1/MUC1 peptide dendritic cell therapy responders by quantification of ex vivo induced mRNA in whole blood].

Cancer immunotherapy has shown much potential, but is not yet beneficial for all patients. Acquired immunity after immunotherapy can be assessed by a variety of methods; however, the methods for the prediction of such responses before treatment are quite limited. To challenge this classic problem, we quantified 17 different leukocyte function-associated mRNAs( IFN-γ,TNFSF1, TNFSF2, TNFSF5, IL-10, TGF ß,CTLA4, PD1, FOXP3, GMCSF, VEGF, IL-8, CCL8, CXCL3, and IL-2) in whole blood after ex vivo stimulation with 7 different agents(PHA, HAG, zymosan, IFN-γ,rIL-2, aTCR, and picibanil) to activate various subsets of leukocytes. The mRNAs were quantified by the Hitachi Chemical Research Center, Inc. Irvine, CA. The clinical outcomes for WT1 peptide-and/or MUC1 peptide-pulsed dendritic cell therapy for advanced cancer (n=26) were CR+PR, 4 cases; SD, 9 cases; and PD, 13 cases. The accuracy of prediction was found to be 100% using the formula developed by multivariate discriminant analysis of the values for ex vivo induced mRNAs. Because the volume of blood needed for this test is less than 1.5 mL, and because cell isolation and culture are not necessary, this method will become a model of personalized medicine diagnostics for cancer immunotherapy.

Tet3 CXXC domain and dioxygenase activity cooperatively regulate key genes for Xenopus eye and neural development.

Ten-Eleven Translocation (Tet) family of dioxygenases dynamically regulates DNA methylation and has been implicated in cell lineage differentiation and oncogenesis. Yet their functions and mechanisms of action in gene regulation and embryonic development are largely unknown. Here, we report that Xenopus Tet3 plays an essential role in early eye and neural development by directly regulating a set of key developmental genes. Tet3 is an active 5mC hydroxylase regulating the 5mC/5hmC status at target gene promoters. Biochemical and structural studies further demonstrate that the Tet3 CXXC domain is critical for specific Tet3 targeting. Finally, we show that the enzymatic activity and CXXC domain are both crucial for Tet3's biological function. Together, these findings define Tet3 as a transcription regulator and reveal a molecular mechanism by which the 5mC hydroxylase and DNA binding activities of Tet3 cooperate to control target gene expression and embryonic development.

The multiple roles of Notch signaling during left-right patterning.

The establishment of left-right (LR) asymmetry is regulated by intricate signaling mechanisms during embryogenesis and this asymmetry is critical for morphogenesis as well as the positioning of internal organs within the organism. Recent progress including elucidation of ion transporters, leftward nodal flow, and regulation of asymmetric gene expression contributes to our understanding of how the breaking of the symmetry is initiated and how this laterality information is subsequently transmitted to the organ primordium. A number of developmental signaling pathways have been implicated in this complex process. In this review, we will focus on the roles of the Notch signaling pathway during development of LR asymmetry. The Notch signaling pathway is a short-range communication system between neighboring cells. While Notch signaling plays essential roles in regulating the morphogenesis of the node and left-specific expression of Nodal in the lateral plate mesoderm, a hallmark gene in LR patterning, Notch signaling also suppresses the expression of Pitx2 that is a direct downstream target of Nodal during later stages of development. This negative activity of Notch signaling towards left-specific activity was recently shown to be inhibited by the B cell lymphoma 6 (BCL6)/BCL6 co-repressor (BcoR) transcriptional repressor complex in a target-specific manner. The complex regulation of Notch-dependent gene expression for LR asymmetry will be highlighted in this review.