Morphological Characteristics of Biliary Strictures after Liver Transplantation Visualized Using SpyGlass™ Cholangioscopy.

Biliary complications following liver transplant are common. Endoscopic retrograde cholangiopancreatography (ERCP) and magnetic resonance cholangiopancreatography (MRCP) are the main techniques used to diagnose and treat biliary complications; however, these techniques have limits to the depth of visualization. In this report, we present five cases of orthotopic liver transplant patients with biliary complications that underwent ERCP- or MRCP-guided cholangioscopy with the SpyGlass™ DS Direct Visualization System (SDDVS).

Mutual inhibition between Prkd2 and Bcl6 controls T follicular helper cell differentiation.

T follicular helper cells (T) participate in germinal center (GC) development and are necessary for B cell production of high-affinity, isotype-switched antibodies. In a forward genetic screen, we identified a missense mutation in , encoding the serine/threonine kinase protein kinase D2, which caused elevated titers of immunoglobulin E (IgE) in the serum. Subsequent analysis of serum antibodies in mice with a targeted null mutation of demonstrated polyclonal hypergammaglobulinemia of IgE, IgG1, and IgA isotypes, which was exacerbated by the T cell-dependent humoral response to immunization.

Research Techniques Made Simple: Forward Genetic Screening to Uncover Genes Involved in Skin Biology.

The primary goals of modern genetics are to identify disease-causing mutations and to define the functions of genes in biological processes. Two complementary approaches, reverse and forward genetics, can be used to achieve this goal. Reverse genetics is a gene-driven approach that comprises specific gene targeting followed by phenotypic assessment.

Enhanced susceptibility to chemically induced colitis caused by excessive endosomal TLR signaling in LRBA-deficient mice.

LPS-responsive beige-like anchor (LRBA) protein deficiency in humans causes immune dysregulation resulting in autoimmunity, inflammatory bowel disease (IBD), hypogammaglobulinemia, regulatory T (T) cell defects, and B cell functional defects, but the cellular and molecular mechanisms responsible are incompletely understood. In an ongoing forward genetic screen for -ethyl--nitrosourea (ENU)-induced mutations that increase susceptibility to dextran sodium sulfate (DSS)-induced colitis in mice, we identified two nonsense mutations in Although T cells have been a main focus in LRBA research to date, we found that dendritic cells (DCs) contribute significantly to DSS-induced intestinal inflammation in LRBA-deficient mice. DCs exhibited excessive IRF3/7- and PI3K/mTORC1-dependent signaling and type I IFN production in response to the stimulation of the Toll-like receptors (TLRs) 3, TLR7, and TLR9.

LMBR1L regulates lymphopoiesis through Wnt/β-catenin signaling.

Precise control of Wnt signaling is necessary for immune system development. In this study, we detected severely impaired development of all lymphoid lineages in mice, resulting from an -ethyl--nitrosourea-induced mutation in the limb region 1-like gene (), which encodes a membrane-spanning protein with no previously described function in immunity. The interaction of LMBR1L with glycoprotein 78 (GP78) and ubiquitin-associated domain-containing protein 2 (UBAC2) attenuated Wnt signaling in lymphocytes by preventing the maturation of FZD6 and LRP6 through ubiquitination within the endoplasmic reticulum and by stabilizing "destruction complex" proteins.

The class I myosin MYO1D binds to lipid and protects against colitis.

Myosin ID (MYO1D) is a member of the class I myosin family. We screened 48,649 third generation (G3) germline mutant mice derived from N-ethyl-N-nitrosourea-mutagenized grandsires for intestinal homeostasis abnormalities after oral administration of dextran sodium sulfate (DSS). We found and validated mutations in as a cause of increased susceptibility to DSS-induced colitis.

Probability of phenotypically detectable protein damage by ENU-induced mutations in the Mutagenetix database.

Computational inference of mutation effects is necessary for genetic studies in which many mutations must be considered as etiologic candidates. Programs such as PolyPhen-2 predict the relative severity of damage caused by missense mutations, but not the actual probability that a mutation will reduce/eliminate protein function. Based on genotype and phenotype data for 116,330 ENU-induced mutations in the Mutagenetix database, we calculate that putative null mutations, and PolyPhen-2-classified "probably damaging", "possibly damaging", or "probably benign" mutations have, respectively, 61%, 17%, 9.

HCFC2 is needed for IRF1- and IRF2-dependent transcription and for survival during viral infections.

Transcriptional regulation of numerous interferon-regulated genes, including (), which encodes an innate immune sensor of viral double-stranded RNA, depends on the interferon regulatory factor 1 (IRF1) and IRF2 transcription factors. We detected specific abrogation of macrophage responses to polyinosinic-polycytidylic acid (poly(I:C)) resulting from three independent -ethyl--nitrosourea-induced mutations in (). mutations compromised survival during influenza virus and herpes simplex virus 1 infections.

Skin-specific regulation of SREBP processing and lipid biosynthesis by glycerol kinase 5.

The recessive -ethyl--nitrosourea-induced phenotype is characterized by delayed hair growth, progressive hair loss, and excessive accumulation of dermal cholesterol, triglycerides, and ceramides. The phenotype was attributed to a null allele of , encoding glycerol kinase 5 (GK5), a skin-specific kinase expressed predominantly in sebaceous glands. GK5 formed a complex with the sterol regulatory element-binding proteins (SREBPs) through their C-terminal regulatory domains, inhibiting SREBP processing and activation.

IgD class switching is initiated by microbiota and limited to mucosa-associated lymphoid tissue in mice.

Class-switch recombination (CSR) alters the Ig isotype to diversify antibody effector functions. IgD CSR is a rare event, and its regulation is poorly understood. We report that deficiency of 53BP1, a DNA damage-response protein, caused age-dependent overproduction of secreted IgD resulting from increased IgD CSR exclusively within B cells of mucosa-associated lymphoid tissues.

Creatine maintains intestinal homeostasis and protects against colitis.

Creatine, a nitrogenous organic acid, replenishes cytoplasmic ATP at the expense of mitochondrial ATP via the phosphocreatine shuttle. Creatine levels are maintained by diet and endogenous synthesis from arginine and glycine. Glycine amidinotransferase (GATM) catalyzes the rate-limiting step of creatine biosynthesis: the transfer of an amidino group from arginine to glycine to form ornithine and guanidinoacetate.

Glycosylation of rhodopsin is necessary for its stability and incorporation into photoreceptor outer segment discs.

Rhodopsin, a G-protein coupled receptor, most abundant protein in retinal rod photoreceptors, is glycosylated at asparagines-2 and 15 on its N-terminus. To understand the role of rhodopsin's glycosylation in vivo, we generated and characterized a transgenic mouse model that expresses a non-glycosylated form of rhodopsin. We show that lack of glycosylation triggers a dominant form of progressive retinal degeneration.

MicroRNA-200b downregulates oxidation resistance 1 (Oxr1) expression in the retina of type 1 diabetes model.

Purpose: MicroRNAs (miRNAs) are known to participate in post-transcriptional regulation of gene expression and are involved in multiple pathogenic processes. Here, we identified miRNA expression changes in the retinas of Akita mice, a genetic model of type 1 diabetes, and investigated the potential role of miRNA in diabetic retinopathy.

Methods: Visual function of Akita and control mice was evaluated by electroretinography.

ENU-induced phenovariance in mice: inferences from 587 mutations.

Background: We present a compendium of N-ethyl-N-nitrosourea (ENU)-induced mouse mutations, identified in our laboratory over a period of 10 years either on the basis of phenotype or whole genome and/or whole exome sequencing, and archived in the Mutagenetix database. Our purpose is threefold: 1) to formally describe many point mutations, including those that were not previously disclosed in peer-reviewed publications; 2) to assess the characteristics of these mutations; and 3) to estimate the likelihood that a missense mutation induced by ENU will create a detectable phenotype.

Findings: In the context of an ENU mutagenesis program for C57BL/6J mice, a total of 185 phenotypes were tracked to mutations in 129 genes.

Identification of a novel inhibitor of the canonical Wnt pathway.

Wnt signaling is known to regulate multiple processes including angiogenesis, inflammation, and fibrosis. Here, we identified a novel inhibitor of the Wnt pathway, pigment epithelium-derived factor (PEDF), a multifunctional serine proteinase inhibitor. Both overexpression of PEDF in transgenic mice and administration of PEDF protein attenuated Wnt signaling induced by retinal ischemia.

Lack of protein-tyrosine sulfation disrupts photoreceptor outer segment morphogenesis, retinal function and retinal anatomy.

To investigate the role(s) of protein-tyrosine sulfation in the retina, we examined retinal function and structure in mice lacking tyrosylprotein sulfotransferases (TPST) 1 and 2. Tpst double knockout (DKO; Tpst1(-/-) /Tpst2 (-/-) ) retinas had drastically reduced electroretinographic responses, although their photoreceptors exhibited normal responses in single cell recordings. These retinas appeared normal histologically; however, the rod photoreceptors had ultrastructurally abnormal outer segments, with membrane evulsions into the extracellular space, irregular disc membrane spacing and expanded intradiscal space.

Rhodopsin: the functional significance of asn-linked glycosylation and other post-translational modifications.

Rhodopsin, the G-protein coupled receptor in retinal rod photoreceptors, is a highly conserved protein that undergoes several types of post-translational modifications. These modifications are essential to maintain the protein's structure as well as its proper function in the visual transduction cycle. Rhodopsin is N-glycosylated at Asn-2 and Asn-15 in its extracellular N-terminal domain.

Interleukin 6 indirectly induces keratinocyte migration.

IL-6-deficient transgenic mice (IL-6 KO) display significantly delayed cutaneous wound healing. To further elucidate the role of IL-6 in skin wound healing, epidermal keratinocyte and dermal fibroblast cells were isolated from neonatal IL-6 KO mice and treated with rmIL-6. It was found that rmIL-6 alone did not significantly modulate the proliferation or migration of cultured IL-6 KO keratinocytes.