The Inv compartment of renal cilia is an intraciliary signal-activating center to phosphorylate ANKS6.

Connections between cilia and renal cystic diseases are well known, yet molecular mechanisms remain undefined. Cysto-proteins localized in the Inv compartment of cilia (INV, NPHP3, NEK8, and ANKS6) constitute a distinct group. Here we created and analyzed mutant mice (G2A mice) with a defective cilia localization signal in the Nphp3 gene. Mutant NPHP3 was absent the binding capacity of UNC119, a carrier protein responsible for the delivery of myristoylated cargo to the cilium, so ciliary localization was reduced or lost in the kidney but not in the embryonic node. Mutant mice developed renal cysts but not situs abnormalities. Although ciliary localization of INV, NEK8, and ANKS6 did not change in the kidneys of Nphp3 mutant mice, ANKS6 phosphorylation was impaired. In general, ANKS6 levels decrease with age in the kidneys of wild-type mice. However, cystic kidneys in G2A and Inv mice maintained high levels of a non-phosphorylated form of ANKS6. We found INV and NPHP3 cooperate and promote ANKS6 phosphorylation by NEK8 in renal cilia. Thus, there is a novel signaling path from cilia in which ANKS6 functions as a signal mediator and link between cilia and the cytoplasm to regulate kidney morphogenesis.

Loss of sorting nexin 5 stabilizes internalized growth factor receptors to promote thyroid cancer progression.

Thyroid carcinoma is the most common endocrine malignancy and its prevalence has recently been increasing worldwide. We previously reported that the level of sorting nexin 5 (Snx5), an endosomal translocator, is preferentially decreased during the progression of well-differentiated thyroid carcinoma into poorly differentiated carcinoma. To address the functional role of Snx5 in the development and progression of thyroid carcinoma, we established Snx5-deficient (Snx5-/- ) mice. In comparison to wild-type (Snx5+/+ ) mice, Snx5-/- mice showed enlarged thyroid glands that consisted of thyrocytes with large irregular-shaped vacuoles. Snx5-/- thyrocytes exhibited a higher growth potential and higher sensitivity to thyroid-stimulating hormone (TSH). A high content of early endosomes enriched with TSH receptors was found in Snx5-/- thyrocytes, suggesting that loss of Snx5 caused retention of the TSH receptor (TSHR) in response to TSH. Similar data were found for internalized EGF in primary thyrocytes. The increased TSH sensitivities in Snx5-/- thyrocytes were also confirmed by results showing that Snx5-/- mice steadily developed thyroid tumors with high metastatic potential under high TSH. Furthermore, a thyroid cancer model using carcinogen and an anti-thyroidal agent revealed that Snx5-/- mice developed metastasizing thyroid tumors with activation of MAP kinase and AKT pathways, which are postulated to be major pathways of malignant progression of human thyroid carcinoma. Our results suggest that thyrocytes require Snx5 to lessen tumorigenic signaling driven by TSH, which is a major risk factor for thyroid carcinoma. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Exophilin-8 assembles secretory granules for exocytosis in the actin cortex via interaction with RIM-BP2 and myosin-VIIa.

Exophilin-8 has been reported to play a role in anchoring secretory granules within the actin cortex, due to its direct binding activities to Rab27 on the granule membrane and to F-actin and its motor protein, myosin-Va. Here, we show that exophilin-8 accumulates granules in the cortical F-actin network not by direct interaction with myosin-Va, but by indirect interaction with a specific form of myosin-VIIa through its previously unknown binding partner, RIM-BP2. RIM-BP2 also associates with exocytic machinery, Cav1.3, RIM, and Munc13-1. Disruption of the exophilin-8-RIM-BP2-myosin-VIIa complex by ablation or knockdown of each component markedly decreases both the peripheral accumulation and exocytosis of granules. Furthermore, exophilin-8-null mouse pancreatic islets lose polarized granule localization at the ß-cell periphery and exhibit impaired insulin secretion. This newly identified complex acts as a physical and functional scaffold and provides a mechanism supporting a releasable pool of granules within the F-actin network beneath the plasma membrane.

Xenopus Vasa Homolog XVLG1 is Essential for Migration and Survival of Primordial Germ Cells.

Xenopus vasa-like gene 1 (XVLG1), a DEAD-Box Helicase 4 (DDX4) gene identified as a vertebrate vasa homologue, is required for the formation of primordial germ cells (PGCs). However, it remains to be clarified when and how XVLG1 functions in the formation of the germ cells. To gain a better understanding of the molecular mechanisms underlying XVLG1 during PGC development, we injected XVLG1 morpholino oligos into germ-plasm containing blastomeres of 32-cell stage of Xenopus embryos, and traced cell fates of the injected blastomere-derived PGCs. As a result of this procedure, migration of the PGCs was impaired and the number of PGCs derived from the blastomeres was significantly decreased. In addition, TUNEL staining in combination with in situ hybridization revealed that the loss of PGCs peaked at stage 27 was caused by apoptosis. This data strongly suggests an essential role for XVLG1 in migration and survival of the germ cells.

Toll-like receptor 4 antagonist TAK-242 inhibits autoinflammatory symptoms in DITRA.

BACKGROUND: IL36RN encodes the IL-36 receptor antagonist (IL-36Ra), and loss-of-function mutations in IL36RN define a recessively inherited autoinflammatory disease named "deficiency of IL-36Ra" (DITRA). DITRA causes systemic autoinflammatory diseases, including generalized pustular psoriasis (GPP), an occasionally life-threatening disease that is characterized by widespread sterile pustules on the skin, fever and other systemic symptoms. GPP can present at any age, and provocative factors include various infections, medicines and pregnancy. OBJECTIVE: We aimed to elucidate the role of toll-like receptor 4 (TLR4) signaling in DITRA and to innovate an efficient treatment for DITRA. METHODS: We generated Il36rn-/- mice and treated them with TLR4 agonist to establish DITRA model mice. Furthermore, we administrated TLR4 antagonist TAK-242 to the model mice to inhibit the DITRA symptoms. RESULT: Il36rn-/- mice treated by TLR4 agonist showed autoinflammatory symptoms in skin, articulation and liver. Thus, we established model mice for DITRA or GPP that show cutaneous, articular, and hepatic autoinflammatory symptoms typical of DITRA or GPP: sterile pustules on the skin, liver abscesses and enthesitis of the hind paws. Additionally, these symptoms were canceled by TAK-242 administration. We demonstrated the inhibitory effects of the TLR4 antagonist TAK-242 on the autoinflammatory symptoms exhibited by the DITRA models. CONCLUSION: We suggested that blockage of TLR4 signaling is a promising treatment for DITRA and GPP.

Nardilysin Is Required for Maintaining Pancreatic ß-Cell Function.

Type 2 diabetes (T2D) is associated with pancreatic ß-cell dysfunction, manifested by reduced glucose-stimulated insulin secretion (GSIS). Several transcription factors enriched in ß-cells, such as MafA, control ß-cell function by organizing genes involved in GSIS. Here we demonstrate that nardilysin (N-arginine dibasic convertase; Nrd1 and NRDc) critically regulates ß-cell function through MafA. Nrd1(-/-) mice showed glucose intolerance and severely decreased GSIS. Islets isolated from Nrd1(-/-) mice exhibited reduced insulin content and impaired GSIS in vitro. Moreover, ß-cell-specific NRDc-deficient (Nrd1(delß)) mice showed a diabetic phenotype with markedly reduced GSIS. MafA was specifically downregulated in islets from Nrd1(delß) mice, whereas overexpression of NRDc upregulated MafA and insulin expression in INS832/13 cells. Chromatin immunoprecipitation assay revealed that NRDc is associated with Islet-1 in the enhancer region of MafA, where NRDc controls the recruitment of Islet-1 and MafA transcription. Our findings demonstrate that NRDc controls ß-cell function via regulation of the Islet-1-MafA pathway.

Differential regulation of T-cell dependent and T-cell independent antibody responses through arginine methyltransferase PRMT1 in vivo.

Protein arginine methyltransferase 1 (PRMT1), a major PRMT in mammalian cells, has been shown to play a crucial role in multiple biological functions in vitro. To explore the role of PRMT1 in B cells in vivo, we generated B cell-specific PRMT1-deficient (Prmt1(-/-) ) mice using a Cre-loxP system. Prmt1(-/-) mice showed a defect in B-cell development with diminished levels of serum antibodies. Antibody responses in Prmt1(-/-) mice were absent after stimulation with the type 2 T cell-independent antigen NP-Ficoll but intact after stimulation with the T cell-dependent antigen NP-OVA. Our findings comprise the first evidence showing that PRMT1 is necessary for lymphocyte functions in vivo.

Fatty acid remodeling by LPCAT3 enriches arachidonate in phospholipid membranes and regulates triglyceride transport.

Polyunsaturated fatty acids (PUFAs) in phospholipids affect the physical properties of membranes, but it is unclear which biological processes are influenced by their regulation. For example, the functions of membrane arachidonate that are independent of a precursor role for eicosanoid synthesis remain largely unknown. Here, we show that the lack of lysophosphatidylcholine acyltransferase 3 (LPCAT3) leads to drastic reductions in membrane arachidonate levels, and that LPCAT3-deficient mice are neonatally lethal due to an extensive triacylglycerol (TG) accumulation and dysfunction in enterocytes. We found that high levels of PUFAs in membranes enable TGs to locally cluster in high density, and that this clustering promotes efficient TG transfer. We propose a model of local arachidonate enrichment by LPCAT3 to generate a distinct pool of TG in membranes, which is required for normal directionality of TG transfer and lipoprotein assembly in the liver and enterocytes.