scholarly journals Fibronectin type III and intracellular domains of Toll-like receptor 4 interactor with leucine-rich repeats (Tril) are required for developmental signaling

2017 ◽  
Author(s):  
Hyung-Seok Kim ◽  
Autumn McKnite ◽  
Yuanyuan Xie ◽  
Jan L. Christian
Keyword(s):  
Embryonic Development ◽  
Cell Surface ◽  
Extracellular Domain ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Intracellular Domain ◽  
Fibronectin Type Iii ◽  
Leucine Rich Repeats ◽  
Fibronectin Type

AbstractToll-like receptor 4 interactor with leucine-rich repeats (Tril) is a transmembrane protein that functions as a coreceptor for Toll-like receptors (Tlrs) to mediate innate immune responses in the adult brain. Tril also triggers degradation of the Bmp inhibitor, Smad7, during early embryonic development to allow for normal blood formation. Tril most likely plays additional, yet to be discovered, roles during embryogenesis. In the current studies, we performed a structure-function analysis, which indicated that the extracellular domain, including the fibronectin type III (FN) domain, and the intracellular domain of Tril are required to trigger Smad7 degradation in the early Xenopus embryo. Furthermore, we found that a Tril deletion mutant lacking the FN domain (TrilΔFN) can dominantly inhibit signaling by endogenous Tril when overexpressed in vivo. This finding raises the intriguing possibility that the FN domain functions to bind endogenous Tril/Tlr4 ligands, perhaps including extracellular matrix molecules. We also show that Tril normally cycles between the cell surface and endosomes, and that the Tril extracellular domain is required to retain Tril at the cell surface, while the intracellular domain is required for Tril internalization in Xenopus ectodermal explants. Using a CHO cell aggregation assay, we further show that, unlike other transmembrane proteins that contain leucine rich repeats in the extracellular domain, Tril is not sufficient to mediate homophilic adhesion. Our findings identify TrilΔFN as a valuable tool that can be used to block the function of endogenous Tril in vivo in order to discover additional roles during embryonic development.

scholarly journals Fibronectin type III and intracellular domains of Toll-like receptor 4 interactor with leucine-rich repeats (Tril) are required for developmental signaling

2018 ◽  
Vol 29 (5) ◽  
pp. 523-531
Author(s):  
Hyung-Seok Kim ◽  
Autumn McKnite ◽  
Yuanyuan Xie ◽  
Jan L. Christian
Keyword(s):  
Cell Surface ◽  
Function Analysis ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Aggregation Assay ◽  
Intracellular Domain ◽  
Type Iii ◽  
Fibronectin Type Iii ◽  
Leucine Rich Repeats ◽  
Fibronectin Type

Toll-like receptor 4 interactor with leucine-rich repeats (Tril) functions as a coreceptor for Toll-like receptors (Tlrs) to mediate innate immune responses in adults. In embryos, Tril signals to promote degradation of the Bmp inhibitor, Smad7, to allow for blood formation. It is not known whether this function requires, or is independent of, Tlrs. In the current studies, we performed a structure–function analysis, which indicated that the fibronectin type III (FN) domain and the intracellular domain of Tril are required to trigger Smad7 degradation in Xenopus embryos. Furthermore, we found evidence suggesting that a Tril deletion mutant lacking the FN domain (Tril∆FN) can dominantly inhibit signaling by endogenous Tril when overexpressed. This finding raises the possibility that the FN domain functions to bind endogenous Tril ligands. We also show that Tril cycles between the cell surface and endosomes and that the Tril extracellular domain, as well as cadherin based cell–cell adhesion, are required for cell surface retention, while the intracellular domain is required for internalization in Xenopus ectodermal explants. Using a CHO cell aggregation assay, we show that, unlike other transmembrane proteins that contain leucine-rich repeats, Tril is not sufficient to mediate homophilic adhesion.

Contributions of extracellular and intracellular domains of full length and chimeric cadherin molecules to junction assembly in epithelial cells

1998 ◽  
Vol 111 (9) ◽  
pp. 1305-1318 ◽  
Author(s):  
S.M. Norvell ◽  
K.J. Green
Keyword(s):  
Epithelial Cells ◽  
Cell Surface ◽  
Extracellular Domain ◽  
Full Length ◽  
Intracellular Domain ◽  
Epithelial Junctions ◽  
Intracellular Domains ◽  
E Cadherin ◽  
Cell Cell

The integrity of cell-cell junctions in epithelial cells depends on functional interactions of both extracellular and intracellular domains of cadherins with other junction proteins. To examine the roles of the different domains of E-cadherin and desmoglein in epithelial junctions, we stably expressed full length desmoglein 1 and chimeras of E-cadherin and desmoglein 1 in A431 epithelial cells. Full length desmoglein 1 was able to incorporate into or disrupt endogenous desmosomes depending on expression level. Each of the chimeric cadherin molecules exhibited distinct localization patterns at the cell surface. A chimera of the desmoglein 1 extracellular domain and the E-cadherin intracellular domain was distributed diffusely at the cell surface while the reverse chimera, comprising the E-cadherin extracellular domain and the desmoglein 1 intracellular domain, localized in large, sometimes contiguous patches at cell-cell interfaces. Nevertheless, both constructs disrupted desmosome assembly. Expression of constructs containing the desmoglein 1 cytoplasmic domain resulted in approximately a 3-fold decrease in E-cadherin bound to plakoglobin and a 5- to 10-fold reduction in the steady-state levels of the endogenous desmosomal cadherins, desmoglein 2 and desmocollin 2, possibly contributing to the dominant negative effect of the desmoglein 1 tail. In addition, biochemical analysis of protein complexes in the stable lines revealed novel in vivo protein interactions. Complexes containing beta-catenin and desmoglein 1 were identified in cells expressing constructs containing the desmoglein 1 tail. Furthermore, interactions were identified between endogenous E-cadherin and the chimera containing the E-cadherin extracellular domain and the desmoglein 1 intracellular domain providing in vivo evidence for previously predicted lateral interactions of E-cadherin extracellular domains.

scholarly journals Estrogens Augment Cell Surface TLR4 Expression on Murine Macrophages and Regulate Sepsis Susceptibility in Vivo

Endocrinology ◽  
2009 ◽  
Vol 150 (8) ◽  
pp. 3877-3884 ◽  
Author(s):  
Jennifer A. Rettew ◽  
Yvette M. Huet ◽  
Ian Marriott
Keyword(s):  
Cell Surface ◽  
Immune Responses ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Toll Like Receptor ◽  
Lipopolysaccharide Binding Protein ◽  
Toll Like Receptor 4 ◽  
17Β Estradiol ◽  
Lipopolysaccharide Binding

Gender-based differences exist in infectious disease susceptibility. In general, females generate more robust and potentially protective humoral and cell-mediated immune responses after antigenic challenge than their male counterparts. Furthermore, evidence is accumulating that sex may also influence the early perception of microbial challenges and the generation of inflammatory immune responses such as sepsis. These differences have previously been attributed to the actions of reproductive hormones. Whereas androgens have been shown to suppress acute host immune responses to bacterial endotoxin challenge, estrogens have been found to promote increased resistance to bacterial infections. However, the mechanisms by which estrogens exert immunoprotective effects have not been established. In this study, we investigated the in vivo effects of 17β-estradiol on endotoxin susceptibility in mice. Importantly, we have examined the actions of this female reproductive hormone on the expression of pattern recognition receptors that recognize bacterial endotoxin by key innate immune sentinel cells. We show that removal of endogenous estrogens decreases both pro- and antiinflammatory cytokine production, with a concomitant reduction in circulating levels of lipopolysaccharide-binding protein and cell surface expression of Toll-like receptor 4 on murine macrophages. Exogenous in vivo replacement of 17β-estradiol, but not progesterone, significantly elevates sera lipopolysaccharide-binding protein levels and cell surface expression of Toll-like receptor 4 and CD14 on macrophages. Furthermore, this effect corresponds with significantly higher inflammatory cytokine levels after in vivo lipopolysaccharide challenge and a marked increase in endotoxin-associated morbidity. Taken together, these data provide a potential mechanism underlying the immunoenhancing effects of estrogens.

scholarly journals Serum Amyloid A1/Toll-Like Receptor-4 Axis, an Important Link between Inflammation and Outcome of TBI Patients

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 599
Author(s):  
Víctor Farré-Alins ◽  
Alejandra Palomino-Antolín ◽  
Paloma Narros-Fernández ◽  
Ana Belen Lopez-Rodriguez ◽  
Céline Decouty-Perez ◽  
...  
Keyword(s):  
Injury Severity ◽  
White Blood Cells ◽  
Serum Amyloid ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Important Link ◽  
Tlr4 Mrna ◽  
Serum Amyloid A1

Traumatic brain injury (TBI) is one of the leading causes of mortality and disability worldwide without any validated biomarker or set of biomarkers to help the diagnosis and evaluation of the evolution/prognosis of TBI patients. To achieve this aim, a deeper knowledge of the biochemical and pathophysiological processes triggered after the trauma is essential. Here, we identified the serum amyloid A1 protein-Toll-like receptor 4 (SAA1-TLR4) axis as an important link between inflammation and the outcome of TBI patients. Using serum and mRNA from white blood cells (WBC) of TBI patients, we found a positive correlation between serum SAA1 levels and injury severity, as well as with the 6-month outcome of TBI patients. SAA1 levels also correlate with the presence of TLR4 mRNA in WBC. In vitro, we found that SAA1 contributes to inflammation via TLR4 activation that releases inflammatory cytokines, which in turn increases SAA1 levels, establishing a positive proinflammatory loop. In vivo, post-TBI treatment with the TLR4-antagonist TAK242 reduces SAA1 levels, improves neurobehavioral outcome, and prevents blood–brain barrier disruption. Our data support further evaluation of (i) post-TBI treatment in the presence of TLR4 inhibition for limiting TBI-induced damage and (ii) SAA1-TLR4 as a biomarker of injury progression in TBI patients.

Lack of Toll-like receptor 4 decreases lipopolysaccharide-induced bone resorption in C3H/HeJ mice in vivo

2008 ◽  
Vol 23 (3) ◽  
pp. 190-195 ◽  
Author(s):  
H. Nakamura ◽  
Y. Fukusaki ◽  
A. Yoshimura ◽  
C. Shiraishi ◽  
M. Kishimoto ◽  
...  
Keyword(s):  
Bone Resorption ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4

scholarly journals Mertk Interacts with Tim-4 to Enhance Tim-4-Mediated Efferocytosis

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1625 ◽  
Author(s):  
Byeongjin Moon ◽  
Juyeon Lee ◽  
Sang-Ah Lee ◽  
Chanhyuk Min ◽  
Hyunji Moon ◽  
...  
Keyword(s):  
Cell Surface ◽  
Molecular Mechanism ◽  
Soluble Form ◽  
Physical Interaction ◽  
Apoptotic Cells ◽  
Type Iii ◽  
Biochemical Interaction ◽  
Fibronectin Type Iii ◽  
Fibronectin Type Iii Domain ◽  
Fibronectin Type

Apoptotic cells expressing phosphatidylserine (PS) on their cell surface are directly or indirectly recognized by phagocytes through PS-binding proteins. The PS-binding protein Tim-4 secures apoptotic cells to phagocytes to facilitate the engulfment of apoptotic cells. However, the molecular mechanism by which Tim-4 transduces signals to phagocytes during Tim-4-mediated efferocytosis is incompletely understood. Here, we report that Tim-4 collaborates with Mertk during efferocytosis through a biochemical interaction with Mertk. Proximal localization between the two proteins in phagocytes was observed by immunofluorescence and proximal ligation assays. Physical association between Tim-4 and Mertk, which was mediated by an interaction between the IgV domain of Tim-4 and the fibronectin type-III domain of Mertk, was also detected with immunoprecipitation. Furthermore, the effect of Mertk on Tim-4-mediated efferocytosis was abolished by GST-MertkFnIII, a soluble form of the fibronectin type-III domain of Mertk that disrupts the interaction between Tim-4 and Mertk. Taken together, the results from our study suggest that a physical interaction between Tim-4 and Mertk is necessary for Mertk to enhance efferocytosis mediated by Tim-4.

scholarly journals Micrococcus luteus Teichuronic Acids Activate Human and Murine Monocytic Cells in a CD14- and Toll-Like Receptor 4-Dependent Manner

2001 ◽  
Vol 69 (4) ◽  
pp. 2025-2030 ◽  
Author(s):  
Shuhua Yang ◽  
Shunji Sugawara ◽  
Toshihiko Monodane ◽  
Masahiro Nishijima ◽  
Yoshiyuki Adachi ◽  
...  
Keyword(s):  
Lipid A ◽  
Micrococcus Luteus ◽  
Dependent Manner ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Necrosis Factor Alpha ◽  
Monocytic Cells ◽  
Tnf Α

ABSTRACT Teichuronic acid (TUA), a component of the cell walls of the gram-positive organism Micrococcus luteus (formerlyMicrococcus lysodeikticus), induced inflammatory cytokines in C3H/HeN mice but not in lipopolysaccharide (LPS)-resistant C3H/HeJ mice that have a defect in the Toll-like receptor 4 (TLR4) gene, both in vivo and in vitro, similarly to LPS (T. Monodane, Y. Kawabata, S. Yang, S. Hase, and H. Takada, J. Med. Microbiol. 50:4–12, 2001). In this study, we found that purified TUA (p-TUA) induced tumor necrosis factor alpha (TNF-α) in murine monocytic J774.1 cells but not in mutant LR-9 cells expressing membrane CD14 at a lower level than the parent J774.1 cells. The TNF-α-inducing activity of p-TUA in J774.1 cells was completely inhibited by anti-mouse CD14 monoclonal antibody (MAb). p-TUA also induced interleukin-8 (IL-8) in human monocytic THP-1 cells differentiated to macrophage-like cells expressing CD14. Anti-human CD14 MAb, anti-human TLR4 MAb, and synthetic lipid A precursor IVA, an LPS antagonist, almost completely inhibited the IL-8-inducing ability of p-TUA, as well as LPS, in the differentiated THP-1 cells. Reduced p-TUA did not exhibit any activities in J774.1 or THP-1 cells. These findings strongly suggested that M. luteus TUA activates murine and human monocytic cells in a CD14- and TLR4-dependent manner, similar to LPS.

Pseudomonas aeruginosa Lipopolysaccharide Induces Osteoclastogenesis Through a Toll-Like Receptor 4 Mediated Pathway in Vitro and in Vivo

2007 ◽  
Vol 117 (5) ◽  
pp. 841-847 ◽  
Author(s):  
Lei Zhuang ◽  
Jae Y. Jung ◽  
Eric W. Wang ◽  
Patrick Houlihan ◽  
Lisette Ramos ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4
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