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1.
Cell Discov ; 4: 15, 2018.
Article in English | MEDLINE | ID: mdl-29619245

ABSTRACT

Connective tissue diseases of the skin are characterized by excessive collagen deposition in the skin and internal organs. Fibroblasts play a pivotal role in the clinical presentation of these conditions. Nuclear receptor peroxisome-proliferator activated receptors (PPARs) are therapeutic targets for dermal fibrosis, but the contribution of the different PPAR subtypes are poorly understood. Particularly, the role of fibroblast PPARß/δ in dermal fibrosis has not been elucidated. Thus, we generated a mouse strain with selective deletion of PPARß/δ in the fibroblast (FSPCre-Pparb/d-/-) and interrogated its epidermal and dermal transcriptome profiles. We uncovered a downregulated gene, leucine-rich alpha-2-glycoprotein-1 (Lrg1), of previously unknown function in skin development and architecture. Our findings suggest that the regulation of Lrg1 by PPARß/δ in fibroblasts is an important signaling conduit integrating PPARß/δ and TGFß1-signaling networks in skin health and disease. Thus, the FSPCre-Pparb/d-/- mouse model could serve as a novel tool in the current gunnery of animal models to better understand dermal fibrosis.

2.
Sci Rep ; 7: 44351, 2017 03 13.
Article in English | MEDLINE | ID: mdl-28287161

ABSTRACT

Many gastrointestinal diseases exhibit a protracted and aggravated inflammatory response that can lead to hypercytokinaemia, culminating in extensive tissue damage. Recently, angiopoietin-like 4 (ANGPTL4) has been implicated in many inflammation-associated diseases. However, how ANGPTL4 regulates colonic inflammation remains unclear. Herein, we show that ANGPTL4 deficiency in mice (ANGPTL4-/-) exacerbated colonic inflammation induced by dextran sulfate sodium (DSS) or stearic acid. Microbiota was similar between the two genotypes prior DSS challenge. A microarray gene expression profile of the colon from DSS-treated ANGPTL4-/- mice was enriched for genes involved in leukocyte migration and infiltration, and showed a close association to inflamed ulcerative colitis (UC), whereas the profile from ANGPTL4+/+ littermates resembled that of non-inflamed UC biopsies. Bone marrow transplantation demonstrates the intrinsic role of colonic ANGPTL4 in regulating leukocyte infiltration during DSS-induced inflammation. Using immortalized human colon epithelial cells, we revealed that the ANGPTL4-mediated upregulation of tristetraprolin expression operates through CREB and NF-κB transcription factors, which in turn, regulates the stability of chemokines. Together, our findings suggest that ANGPTL4 protects against acute colonic inflammation and that its absence exacerbates the severity of inflammation. Our findings emphasize the importance of ANGPTL4 as a novel target for therapy in regulating and attenuating inflammation.


Subject(s)
Angiopoietin-Like Protein 4/genetics , Chemokines/genetics , Colon/metabolism , Gene Expression Profiling , Inflammation/genetics , Tristetraprolin/genetics , Angiopoietin-Like Protein 4/metabolism , Animals , Cell Line , Chemokines/metabolism , Colitis, Ulcerative/genetics , Colitis, Ulcerative/metabolism , Colon/pathology , Dextran Sulfate , Humans , Inflammation/chemically induced , Inflammation/metabolism , Mice, Inbred C57BL , Mice, Knockout , RNA Stability , Stearic Acids , THP-1 Cells , Tristetraprolin/metabolism
3.
Cell Death Dis ; 8(1): e2562, 2017 01 19.
Article in English | MEDLINE | ID: mdl-28102840

ABSTRACT

Histological inspection of visually normal tissue adjacent to neoplastic lesions often reveals multiple foci of cellular abnormalities. This suggests the presence of a regional carcinogenic signal that spreads oncogenic transformation and field cancerization. We observed an abundance of mutagenic reactive oxygen species in the stroma of cryosectioned patient tumor biopsies, indicative of extratumoral oxidative stress. Diffusible hydrogen peroxide (H2O2) was elevated in the conditioned medium of cultured skin epithelia at various stages of oncogenic transformation, and H2O2 production increased with greater tumor-forming and metastatic capacity of the studied cell lines. Explanted cancer-associated fibroblasts (CAFs) also had higher levels of H2O2 secretion compared with normal fibroblasts (FIBs). These results suggest that extracellular H2O2 acts as a field effect carcinogen. Indeed, H2O2-treated keratinocytes displayed decreased phosphatase and tensin homolog (PTEN) and increased Src activities because of oxidative modification. Furthermore, treating FIBs with CAF-conditioned medium or exogenous H2O2 resulted in the acquisition of an oxidative, CAF-like state. In vivo, the proliferative potential and invasiveness of composite tumor xenografts comprising cancerous or non-tumor-forming epithelia with CAFs and FIBs could be attenuated by the presence of catalase. Importantly, we showed that oxidatively transformed FIBs isolated from composite tumor xenografts retained their ability to promote tumor growth and aggressiveness when adoptively transferred into new xenografts. Higher H2O2 production by CAFs was contingent on impaired TGFß signaling leading to the suppression of the antioxidant enzyme glutathione peroxidase 1 (GPX1). Finally, we detected a reduction in Smad3, TAK1 and TGFßRII expression in a cohort of 197 clinical squamous cell carcinoma (SCC) CAFs, suggesting that impaired stromal TGFß signaling may be a clinical feature of SCC. Our study indicated that CAFs and cancer cells engage redox signaling circuitries and mitogenic signaling to reinforce their reciprocal relationship, suggesting that future anticancer approaches should simultaneously target ligand receptor and redox-mediated pathways.


Subject(s)
Breast Neoplasms/genetics , Cancer-Associated Fibroblasts/metabolism , Carcinoma, Squamous Cell/genetics , Oxidative Stress/genetics , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cancer-Associated Fibroblasts/pathology , Carcinoma, Squamous Cell/metabolism , Carcinoma, Squamous Cell/pathology , Cell Line, Tumor , Cell Transformation, Neoplastic/genetics , Female , Gene Expression Regulation, Neoplastic , Humans , Hydrogen Peroxide/metabolism , PTEN Phosphohydrolase/biosynthesis , PTEN Phosphohydrolase/genetics , Reactive Oxygen Species/metabolism , Signal Transduction/drug effects , Transforming Growth Factor beta/biosynthesis , Transforming Growth Factor beta/genetics , Xenograft Model Antitumor Assays
4.
Biochem J ; 451(3): 365-74, 2013 May 01.
Article in English | MEDLINE | ID: mdl-23425532

ABSTRACT

The CorA family of divalent cation transporters utilizes Mg2+ and Co2+ as primary substrates. The molecular mechanism of its function, including ion selectivity and gating, has not been fully characterized. Recently we reported a new structure of a CorA homologue from Methanocaldococcus jannaschii, which provided novel structural details that offered the conception of a unique gating mechanism involving conversion of an open hydrophilic gate into a closed hydrophobic one. In the present study we report functional evidence for this novel gating mechanism in the Thermotoga maritima CorA together with an improved crystal structure of this CorA to 2.7 Å (1 Å=0.1 nm) resolution. The latter reveals the organization of the selectivity filter to be similar to that of M. jannaschii CorA and also the previously unknown organization of the second signature motif of the CorA family. The proposed gating is achieved by a helical rotation upon the binding of a metal ion substrate to the regulatory binding sites. Additionally, our data suggest that the preference of this CorA for Co2+ over Mg2+ is controlled by the presence of threonine side chains in the channel. Finally, the roles of the intracellular metal-binding sites have been assigned to increased thermostability and regulation of the gating. These mechanisms most likely apply to the entire CorA family as they are regulated by the highly conserved amino acids.


Subject(s)
Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Cation Transport Proteins/chemistry , Cation Transport Proteins/metabolism , Cobalt/chemistry , Magnesium/chemistry , Thermotoga maritima/metabolism , Amino Acid Motifs , Bacterial Proteins/genetics , Binding Sites , Biological Transport , Cation Transport Proteins/genetics , Cations, Divalent , Cobalt/metabolism , Crystallography, X-Ray , Escherichia coli/genetics , Hydrophobic and Hydrophilic Interactions , Ion Channel Gating , Kinetics , Magnesium/metabolism , Models, Molecular , Molecular Sequence Data , Mutation , Protein Structure, Secondary , Protein Structure, Tertiary , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Thermotoga maritima/genetics
5.
Proc Natl Acad Sci U S A ; 109(45): 18459-64, 2012 Nov 06.
Article in English | MEDLINE | ID: mdl-23091000

ABSTRACT

Despite the importance of Mg(2+) for numerous cellular activities, the mechanisms underlying its import and homeostasis are poorly understood. The CorA family is ubiquitous and is primarily responsible for Mg(2+) transport. However, the key questions-such as, the ion selectivity, the transport pathway, and the gating mechanism-have remained unanswered for this protein family. We present a 3.2 Å resolution structure of the archaeal CorA from Methanocaldococcus jannaschii, which is a unique complete structure of a CorA protein and reveals the organization of the selectivity filter, which is composed of the signature motif of this family. The structure reveals that polar residues facing the channel coordinate a partially hydrated Mg(2+) during the transport. Based on these findings, we propose a unique gating mechanism involving a helical turn upon the binding of Mg(2+) to the regulatory intracellular binding sites, and thus converting a polar ion passage into a narrow hydrophobic pore. Because the amino acids involved in the uptake, transport, and gating are all conserved within the entire CorA family, we believe this mechanism is general for the whole family including the eukaryotic homologs.


Subject(s)
Archaeal Proteins/chemistry , Archaeal Proteins/metabolism , Ion Channel Gating , Magnesium/metabolism , Methanococcales/metabolism , Binding Sites , Biological Transport , Ion Transport , Ions , Models, Molecular
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