Vasohibin‐2 (VASH2) is expressed in various cancers and promotes their progression. We recently reported that pancreatic cancer patients with higher VASH2 expression show poorer prognosis. Herein, we sought to characterize the role of VASH2 in pancreatic cancer. We used LSL‐KrasG12D; LSL‐Trp53R172H; Pdx‐1‐Cre (KPC) mice, a mouse model of pancreatic ductal adenocarcinoma (PDAC), and cells isolated from them (KPC cells). Knockdown of Vash2 from PDAC cells did not affect their proliferation, but decreased their migration. When Vash2‐knockdown PDAC cells were orthotopically inoculated, liver metastasis and peritoneal dissemination were reduced, and the survival period was significantly prolonged. When KPC mice were crossed with Vash2‐deficient mice, metastasis was significantly decreased in Vash2‐deficient KPC mice. VASH2 was recently identified to have tubulin carboxypeptidase activity. VASH2 knockdown decreased, whereas VASH2 overexpression increased tubulin detyrosination of PDAC cells, and tubulin carboxypeptidase (TCP) inhibitor parthenolide inhibited VASH2‐induced cell migration. We next clarified its role in the tumor microenvironment. Tumor angiogenesis was significantly abrogated in vivo when VASH2 was knocked down or deleted. We further examined genes downregulated by Vash2 knockdown in KPC cells, and found chemokines and cytokines that were responsible for the recruitment of myeloid derived suppressor cells (MDSC). Indeed, MDSC were accumulated in PDAC of KPC mice, and they were significantly decreased in Vash2‐deficient KPC mice. These findings suggest that VASH2 plays an essential role in the metastasis of PDAC with multiple effects on both cancer cells and the tumor microenvironment, including tubulin detyrosination, tumor angiogenesis and evasion of tumor immunity.

Spermatozoa need to undergo an exocytotic event called the acrosome reaction before fusing with eggs. Although calcium ion (Ca 2+ ) is essential for the acrosome reaction, its molecular mechanism remains unknown. Ferlin is a single transmembrane protein with multiple Ca 2+ -binding C2 domains, and there are six ferlins, dysferlin (DYSF), otoferlin (OTOF), myoferlin (MYOF), fer-1–like 4 (FER1L4), FER1L5, and FER1L6, in mammals. Dysf , Otof , and Myof knockout mice have been generated, and each knockout mouse line exhibited membrane fusion disorders such as muscular dystrophy in Dysf , deafness in Otof , and abnormal myogenesis in Myof . Here, by generating mutant mice of Fer1l4 , Fer1l5 , and Fer1l6 , we found that only Fer1l5 is required for male fertility. Fer1l5 mutant spermatozoa could migrate in the female reproductive tract and reach eggs, but no acrosome reaction took place. Even a Ca 2+ ionophore cannot induce the acrosome reaction in Fer1l5 mutant spermatozoa. These results suggest that FER1L5 is the missing link between Ca 2+ and the acrosome reaction.

Human herpesvirus 6B (HHV-6B), a T-lymphotropic virus, infects almost exclusively humans. An animal model of HHV-6B has not been available. Here, we report the first animal model to mimic HHV-6B pathogenesis; the model is based on humanized mice in which human immune cells were engrafted and maintained. For HHV-6B replication, adequate human T-cell activation (which becomes susceptible to HHV-6B) is necessary in this murine model. Here, we found that an additional transfer of human mononuclear cells to humanized mice resulted in an explosive proliferation of human activated T cells, which could be representative of graft-versus-host disease (GVHD) because the primary transfer of human cells was not sufficient to increase the number and ratio of human T cells. Mice infected with HHV-6B became weak and/or died approximately 7 to 14 days later. Quantitative PCR analysis revealed that the spleen and lungs were the major sites of HHV-6B replication in this model, and this was corroborated by the detection of viral proteins in these organs. Histological analysis also revealed the presence of megakaryocytes, indicating HHV-6B infection. Multiplex analysis of cytokines/chemokines in sera from the infected mice showed secretions of human cytokines/chemokines as reported for both in vitro infection and clinical samples, indicating that the secreted cytokines could affect pathogenesis. This is the first animal model showing HHV-6B pathogenesis, and it will be useful for elucidating the pathogenicity of HHV-6B, which is related to GVHD and idiopathic pneumonia syndrome. IMPORTANCE Human herpesvirus 6B (HHV-6B) is a ubiquitous virus that establishes lifelong latent infection only in humans, and the infection can reactivate, with severe complications that cause major problems. A small-animal model of HHV-6B infection has thus been desired for research regarding the pathogenicity of HHV-6B and the development of antiviral agents. We generated humanized mice by transplantation with human hematopoietic stem cells, and here, we modified the model by providing an additional transfer of human mononuclear cells, providing the proper conditions for efficient HHV-6B infection. This is the first humanized mouse model to mimic HHV-6B pathogenesis, and it has great potential for research into the in vivo pathogenesis of HHV-6B.

Conventional dendritic cells (cDCs) are required for peripheral T cell homeostasis in lymphoid organs, but the molecular mechanism underlying this requirement has remained unclear. We here show that T cell–specific CD47-deficient ( Cd47  ΔT ) mice have a markedly reduced number of T cells in peripheral tissues. Direct interaction of CD47-deficient T cells with cDCs resulted in activation of the latter cells, which in turn induced necroptosis of the former cells. The deficiency and cell death of T cells in Cd47   ΔT mice required expression of its receptor signal regulatory protein α on cDCs. The development of CD4 + T helper cell–dependent contact hypersensitivity and inhibition of tumor growth by cytotoxic CD8 + T cells were both markedly impaired in Cd47  ΔT mice. CD47 on T cells thus likely prevents their necroptotic cell death initiated by cDCs and thereby promotes T cell survival and function.

Calcium signaling is critical for successful fertilization. In spermatozoa, calcium influx into the sperm flagella mediated by the sperm specific CatSper calcium channel is necessary for hyperactivated motility and male fertility. CatSper is a macromolecular complex and is repeatedly arranged in zigzag rows within four linear nanodomains along the sperm flagella. Here, we report that theTmem249-encoded transmembrane domain containing protein, CATSPERθ is essential for the CatSper channel assembly during sperm tail formation. CATSPERθ facilitates the channel assembly by serving as a scaffold for a pore forming subunit CATSPER4. CATSPERθ is specifically localized at the interface of a CatSper dimer and can self-interact, suggesting its potential role in CatSper dimer formation. Male mice lacking CATSPERθ are infertile because the sperm lack the entire CatSper channel from sperm flagella, rendering sperm unable to hyperactivate, regardless of their normal expression in the testis. In contrast, genetic abrogation of any of the other CatSper transmembrane subunits results in loss of CATSPERθ protein in the spermatid cells during spermatogenesis. CATSPERθ might acts as a checkpoint for the properly assembled CatSper channel complex to traffic to sperm flagella. This study provides insights into the CatSper channel assembly and elucidates the physiological role of CATSPERθ in sperm motility and male fertility.

Background Lactate dehydrogenase C (LDHC) is specifically expressed in male germ cells and plays critical roles in glycolysis. Glycolysis is required to supply energy for sperm motility. Previous studies showed that Ldhc knock‐out mice exhibit impaired sperm motility. Objectives We established human LDHC knock‐in (hLDHC KI) mice and examined whether hLDHC KI mice can be used to assess LDHC‐targeting drugs. Material and methods HLDHC was knocked‐in to the mouse Ldhc (mLdhc) allele using the CRISPR/Cas9 system. Mating tests, sperm motility examinations with a computer‐assisted sperm analysis (CASA) system, and in vitro fertilization (IVF) were performed. Furthermore, the effect of an LDH inhibitor was analyzed with CASA and IVF. Results HLDHC was detected at the protein level in hLDHC KI spermatozoa. hLDHC KI mice exhibited comparable sperm motility and male fertility to wild‐type (WT) mice. When we performed IVF using the LDH inhibitor more specific to hLDHC than mLDHC, fertilization rates were reduced in hLDHC KI mice but not in WT mice. Discussion and conclusion Our results reveal that hLDHC can rescue the absence of mLDHC. Differences in the effect of the LDH inhibitor between WT and hLDHC KI mice indicate that hLDHC KI mice can be a good model to assess hLDHC inhibitors for preclinical contraceptive studies.

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