Receptor tyrosine kinases Tyro3, Axl, and Mertk differentially contribute to antibody-induced arthritis.

Tyro3, Axl, and Mertk (abbreviated TAMs) comprise a family of homologous type 1 receptor tyrosine kinases (RTKs) that have been implicated as inhibitory receptors that dampen inflammation, but their roles in the pathogenesis of rheumatoid arthritis remains understudied. Here, to investigate TAMs in an inflammatory arthritis model, antibody-induced arthritis in single TAM-deficient mice (Tyro3- KO, Axl-KO, Mertk-KO) was induced by K/BxN serum injection. Subsequently, joint inflammation and cytokine levels, as well as the expression of Fcγ Rs and complement receptors were assessed in WT and TAM-deficient mice.

Characterization and clinical evaluation of microsatellite instability and loss of heterozygosity within tumor-related genes in colorectal cancer.

Background: Microsatellite instability (MSI) is a biomarker for better outcomes in colorectal cancer (CRC). However, this conclusion is controversial. In addition, MSs can be a useful marker for loss of heterozygosity (LOH) of genes, but this finding has not been well studied.

Heterozygous Loss of Yap1 in Mice Causes Progressive Cataracts.

Purpose: Yap1 encodes an evolutionarily conserved transcriptional coactivator and functions as a down-stream effector of the Hippo signaling pathway that controls tissue size and cell growth. Yap1 contributes to lens epithelial development. However, the effect of Yap1 haplodeficiency on the lens epithelium and its role in the development of cataracts has not been reported.

Yap1 is required for maintenance of adult RPE differentiation.

Nuclear YAP1 plays a critical role in regulation of stem cell proliferation, tissue regeneration, and organ size in many types of epithelia. Due to rapid turnover of most epithelial cell types, the cytoplasmic function of YAP1 in epithelial cells has not been well studied. The retinal pigment epithelium (RPE) is a highly polarized epithelial cell type maintained at a senescence state, and offers an ideal cell model to study the active role of YAP1 in maintenance of the adult epithelial phenotype.

Metabolic Deregulation of the Blood-Outer Retinal Barrier in Retinitis Pigmentosa.

Retinitis pigmentosa (RP) initiates with diminished rod photoreceptor function, causing peripheral and night-time vision loss. However, subsequent loss of cone function and high-resolution daylight and color vision is most debilitating. Visual pigment-rich photoreceptor outer segments (OS) undergo phagocytosis by the retinal pigment epithelium (RPE), and the RPE also acts as a blood-outer retinal barrier transporting nutrients, including glucose, to photoreceptors.

TAM Kinases Promote Necroptosis by Regulating Oligomerization of MLKL.

Necroptosis, a cell death pathway mediated by the RIPK1-RIPK3-MLKL signaling cascade downstream of tumor necrosis factor α (TNF-α), has been implicated in many inflammatory diseases. Members of the TAM (Tyro3, Axl, and Mer) family of receptor tyrosine kinases are known for their anti-apoptotic, oncogenic, and anti-inflammatory roles. Here, we identify an unexpected role of TAM kinases as promoters of necroptosis, a pro-inflammatory necrotic cell death.

Tyro3, Axl, and Mertk receptors differentially participate in platelet activation and thrombus formation.

Background: Previously, several studies have shown that Tyro3, Axl, and Mertk (TAM) receptors participate in platelet activation and thrombosis. However, the role of individual receptors is not fully understood.

Methods: Using single receptor-deficient platelets from TAM knockout mice in the C57BL/6 J strain, we performed a knockout study using single TAM-deficient mice.

Indications and Outcomes of Penetrating Keratoplasty in Infants and Children of Beijing, China.

Purpose: To retrospectively investigate the indications and outcomes of pediatric penetrating keratoplasty (PKP) and to explore factors that affect graft survival.

Methods: Patients who had undergone PKP from May 2010 to December 2016, aged ≤12 years were categorized as infants (≥3 months and <4 years) or children (≥4 years and ≤12 years). Clinical data including patient demographics, indications, surgical procedures, postoperative follow-up, and graft clarity were recorded and analyzed.

Expression of cytokines in aqueous humor from fungal keratitis patients.

Background: Although a series of reports on corneal fungal infection have been published, studies on pathogenic mechanisms and inflammation-associated cytokines remain limited. In this study, aqueous humor samples from fungal keratitis patients were collected to examine cytokine patterns and cellular profile for the pathogenesis of fungal keratitis.

Methods: The aqueous humor samples were collected from ten patients with advanced stage fungal keratitis.

Study of corneal epithelial progenitor origin and the Yap1 requirement using keratin 12 lineage tracing transgenic mice.

Key issues in corneal epithelium biology are the mechanism for corneal epithelium stem cells to maintain the corneal epithelial homeostasis and wound healing responses, and what are the regulatory molecular pathways involved. There are apparent discrepancies about the locations of the progenitor populations responsible for corneal epithelial self-renewal. We have developed a genetic mouse model to trace the corneal epithelial progenitor lineages during adult corneal epithelial homeostasis and wound healing response.

IKK2 inhibition using TPCA-1-loaded PLGA microparticles attenuates laser-induced choroidal neovascularization and macrophage recruitment.

The inhibition of NF-κB by genetic deletion or pharmacological inhibition of IKK2 significantly reduces laser-induced choroid neovascularization (CNV). To achieve a sustained and controlled intraocular release of a selective and potent IKK2 inhibitor, 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1) (MW: 279.29), we developed a biodegradable poly-lactide-co-glycolide (PLGA) polymer-delivery system to further investigate the anti-neovascularization effects of IKK2 inhibition and in vivo biosafety using laser-induced CNV mouse model.

Enhancement of COPD biological networks using a web-based collaboration interface.

The construction and application of biological network models is an approach that offers a holistic way to understand biological processes involved in disease. Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory disease of the airways for which therapeutic options currently are limited after diagnosis, even in its earliest stage. COPD network models are important tools to better understand the biological components and processes underlying initial disease development.

14-3-3σ regulates keratinocyte proliferation and differentiation by modulating Yap1 cellular localization.

The homozygous repeated epilation (Er/Er) mouse mutant of the gene encoding 14-3-3σ displays an epidermal phenotype characterized by hyperproliferative keratinocytes and undifferentiated epidermis. Heterozygous Er/+ mice develop spontaneous skin tumors and are highly sensitive to tumor-promoting 7,12-dimethylbenzanthracene/12-O-tetradecanoyl-phorbol-13-acetate induction. The molecular mechanisms underlying 14-3-3σ regulation of epidermal proliferation, differentiation, and tumor formation have not been well elucidated.

Mertk deficiency affects macrophage directional migration via disruption of cytoskeletal organization.

Mertk belongs to the Tyro3, Axl and Mertk (TAM) family of receptor tyrosine kinases, and plays a pivotal role in regulation of cytoskeletal rearrangement during phagocytosis. Phagocytosis by either professional or non-professional phagocytes is impaired in the Mertk deficient individual. In the present study, we further investigated the effects of Mertk mutation on peritoneal macrophage morphology, attachment, spreading and movement.

Mertk deficiency alters expression of micrornas in the retinal pigment epithelium cells.

Phagocytic clearance of the spent photoreceptor outer segments (OS) by RPE cells is regulated by circadian rhythm cycle and is essential for photoreceptor integrity and function. Mertk regulates RPE phagocytosis and a deficiency in Mertk causes photoreceptor degeneration and visual loss. This study aimed to investigate Mertk regulation of the microRNAs (miRNA), potentially regulating expression of their target genes, which affect phagocytosis.

TAM receptors support neural stem cell survival, proliferation and neuronal differentiation.

Tyro3, Axl and Mertk (TAM) receptor tyrosine kinases play multiple functional roles by either providing intrinsic trophic support for cell growth or regulating the expression of target genes that are important in the homeostatic regulation of immune responses. TAM receptors have been shown to regulate adult hippocampal neurogenesis by negatively regulation of glial cell activation in central nervous system (CNS). In the present study, we further demonstrated that all three TAM receptors were expressed by cultured primary neural stem cells (NSCs) and played a direct growth trophic role in NSCs proliferation, neuronal differentiation and survival.

TAM receptor deficiency affects adult hippocampal neurogenesis.

The Tyro3, Axl and Mertk (TAM) subfamily of receptor protein tyrosine kinases functions in cell growth, differentiation, survival, and most recently found, in the regulation of immune responses and phagocytosis. All three receptors and their ligands, Gas6 (growth arrest-specific gene 6) and protein S, are expressed in the central nervous system (CNS). TAM receptors play pivotal roles in adult hippocampal neurogenesis.

Deciphering TGF-β3 function in medial edge epithelium specification and fusion during mouse secondary palate development.

Background: Transforming growth factor-β3 (TGF-β3) plays a central role in mediating secondary palate fusion along the facial midline. However, the mechanisms by which TGF-β3 functions during secondary palate fusion are still poorly understood.

Results: We found that mouse cytokeratin 6α and 17 mRNAs were expressed exclusively in the palate medial edge epithelium on embryonic day 14.

IKK2 inhibition attenuates laser-induced choroidal neovascularization.

Choroidal neovascularization (CNV) is aberrant angiogenesis associated with exudative age-related macular degeneration (AMD), a leading cause of blindness in the elderly. Inflammation has been suggested as a risk factor for AMD. The IKK2/NF-κB pathway plays a key role in the inflammatory response through regulation of the transcription of cytokines, chemokines, growth factors and angiogenic factors.

HMGB1 is an early and critical mediator in an animal model of uveitis induced by IRBP-specific T cells.

It is largely unknown how invading autoreactive T cells initiate the pathogenic process inside the diseased organ in organ-specific autoimmune disease. In this study, we used a chronic uveitis disease model in mice--EAU--induced by adoptive transfer of uveitogenic IRBP-specific T cells and showed that HMGB1, an important endogenous molecule that serves as a danger signal, was released rapidly from retinal cells into the ECM and intraocular fluid in response to IRBP-specific T cell transfer. HMGB1 release required direct cell-cell contact between retinal cells and IRBP-specific T cells and was an active secretion from intact retinal cells.

TAM receptors affect adult brain neurogenesis by negative regulation of microglial cell activation.

TAM tyrosine kinases play multiple functional roles, including regulation of the target genes important in homeostatic regulation of cytokine receptors or TLR-mediated signal transduction pathways. In this study, we show that TAM receptors affect adult hippocampal neurogenesis and loss of TAM receptors impairs hippocampal neurogenesis, largely attributed to exaggerated inflammatory responses by microglia characterized by increased MAPK and NF-κB activation and elevated production of proinflammatory cytokines that are detrimental to neuron stem cell proliferation and neuronal differentiation. Injection of LPS causes even more severe inhibition of BrdU incorporation in the Tyro3(-/-)Axl(-/-)Mertk(-/-) triple-knockout (TKO) brains, consistent with the LPS-elicited enhanced expression of proinflammatory mediators, for example, IL-1β, IL-6, TNF-α, and inducible NO synthase, and this effect is antagonized by coinjection of the anti-inflammatory drug indomethacin in wild-type but not TKO brains.

Exosomes from retinal astrocytes contain antiangiogenic components that inhibit laser-induced choroidal neovascularization.

Exosomes released from different types of host cells have different biological effects. We report that exosomes released from retinal astroglial cells (RACs) suppress retinal vessel leakage and inhibit choroidal neovascularization (CNV) in a laser-induced CNV model, whereas exosomes released from retinal pigmental epithelium do not. RAC exosomes inhibit the migration of macrophages and the tubule forming of mouse retinal microvascular endothelial cells.

Systemic autoimmunity in TAM triple knockout mice causes inflammatory brain damage and cell death.

The Tyro3, Axl and Mertk (TAM) triply knockout (TKO) mice exhibit systemic autoimmune diseases, with characteristics of increased proinflammatory cytokine production, autoantibody deposition and autoreactive lymphocyte infiltration into a variety of tissues. Here we show that TKO mice produce high level of serum TNF-α and specific autoantibodies deposited onto brain blood vessels. The brain-blood barrier (BBB) in mutant brains exhibited increased permeability for Evans blue and fluorescent-dextran, suggesting a breakdown of the BBB in the mutant brains.

Repression of Zeb1 and hypoxia cause sequential mesenchymal-to-epithelial transition and induction of aid, Oct4, and Dnmt1, leading to immortalization and multipotential reprogramming of fibroblasts in spheres.

In this study, we demonstrate that sphere formation triggers immortalization and stable reprogramming of mouse fibroblasts. Cell contact signaling in spheres causes downregulation of the epithelial-to-mesenchymal transition transcription factor Zeb1 leading to rapid mesenchymal-to-epithelial transition. Hypoxia within spheres together with loss of Zeb1 repression synergize to cause superinduction of Hif1a, which in turn leads to induction of the DNA demethylase Aid/Aicda, demethylation of the Oct4 promoter/enhancer and multipotency.