TGFβ1-induced Amelotin gene expression is downregulated by Bax expression in mouse gingival epithelial cells

The role of FGF9-mediated TGF-β1/Smad signaling in enamel hypoplasia induced by exposure to fluoride and SO2 in rats

Many geographical areas of the world are polluted by both fluoride and sulfur dioxide (SO2). However, the effects of simultaneous exposure to fluoride and SO2 on teeth are unknown. Fibroblast growth factor-9 (FGF9) and transforming growth factor-β1 (TGF-β1) are key signaling molecules in enamel development. The purpose of the study was to explore the effects of co-exposure to fluoride and sulfur dioxide on enamel and to investigate the role and mechanism of FGF9 and TGF-β1. First, sodium fluoride (NaF) and SO2 derivatives were used to construct rat models and evaluate the enamel development of rats. Then, TGF-β1 (cytokine) treatment, SIS3 (inhibitor) treatment and FGF9 gene knockdown were used to explore the mechanism of enamel damage in vitro. The results showed that enamel column crystals in the exposed group were characterized by enamel hypoplasia, as indicated by alterations such as disarrangement of enamel column crystals, space widening and breakage. Ameloblasts also showed pathological changes such as ribosome loss, mitochondrial swelling, nuclear fragmentation and chromatin aggregation. The protein expression of FGF9 was higher and the protein expression of AMBN, TGF-β1 and p-Smad2/3 protein was lower in the groups treated with fluoride and SO2 individually or in combination compared with the control group. Further studies showed that TGF-β1 significantly upregulated p-Smad2/3 and AMBN protein expression and reduced the inhibitory effects of fluoride and SO2; furthermore, SISI blocked the effect of TGF-β1. In addition, knockdown of FGF9 upregulated TGF-β1 protein expression, further activated Smad2/3 phosphorylation, eliminated the inhibitory effects of fluoride and SO2, and increased the protein expression of AMBN. In brief, the study confirms that co-exposure to fluoride and SO2 can result in enamel hypoplasia in rats and indicates that the underlying mechanism may be closely related to the effect of FGF9 on enamel matrix protein secretion through inhibition of the TGF-β1/Smad signaling pathway.

Peptidome characterization of ovarian cancer serum and the identification of tumor suppressive peptide ZYX36-58

Background

Several serum biomarkers, including miRNA, mRNA, protein and peptides in cancer patients are also important mediators of cancer progression.

Methods

The differentially expressed peptides between the serum of ovarian cancer patients and healthy controls were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The function of the peptides was analyzed by CCK8, transwell, wound healing, and flow cytometry analysis. And the mechanism of the peptides was analyzed by peptide pull down, and high-throughput RNA-sequencing.

Results

A total of 7 and 46 peptides were significantly up-regulated and down-regulated in the serum of ovarian cancer patients, respectively. The precursor proteins of the differentially expressed peptides mainly involved in the complement and coagulation cascades, platelet activation, phagosome and focal adhesion pathways. Interestingly, focal adhesion, platelet activation, platelet-cancer cell interaction, complement activation, coagulation cascades and phagosome formation are all critical factors for cancer initiation or progression, which indicated that the peptides may play a crucial role in cancer development. And we identified one peptide, ZYX_36-58, which was down-regulated in the serum of ovarian cancer patients, significantly inhibited invasion and migration and promoted the apoptosis of ovarian cancer cells. Mechanistic study indicated that ZYX_36-58 interacted with and increased the protein level of the antiangiogenic protein thrombospondin-1 (TSP1), which has a tumor suppressive effect on ovarian cancer.

Conclusions

ZYX_36-58, which was significantly down-regulated in the serum of ovarian cancer patients can significantly inhibit cell invasion, migration and promote apoptosis of ovarian cancer cells by binding and up-regulating TSP1 protein expression.

Recombinant adiponectin peptide promotes neuronal survival after intracerebral haemorrhage by suppressing mitochondrial and ATF4-CHOP apoptosis pathways in diabetic mice via Smad3 signalling inhibition

Objective

Low levels of adiponectin (APN), a biomarker of diabetes mellitus, have been implicated in the poor outcome of intracerebral haemorrhage (ICH). Herein, we aimed to demonstrate the neuroprotective effects of a blood‐brain barrier‐permeable APN peptide (APNp) on ICH injury in diabetic mice and explore the underlying mechanisms.

Materials and methods

Recombinant APNp was administrated intraperitoneally to mice with collagenase‐induced ICH. Neurological deficits, brain water content and neural apoptosis were assessed. Western blotting, immunofluorescence staining, quantitative RT‐PCR and transmission electron microscopy were used to determine the signalling pathways affected by APNp.

Results

Adiponectin peptide significantly alleviated neural apoptosis, neurological deficits and brain oedema following ICH in diabetic mice. Mechanistically, APNp promoted the restoration of peroxisome proliferator‐activated receptor gamma coactivator (PGC)‐1α related mitochondrial function and suppressed activating transcription factor 4 (ATF4)‐CCAAT‐enhancer‐binding protein homologous protein (CHOP)‐induced neural apoptosis. Furthermore, Smad3 signalling was found to play a regulatory role in this process by transcriptionally regulating the expression of PGC‐1α and ATF4. APNp significantly suppressed the elevated phosphorylation and nuclear translocation of Smad3 after ICH in diabetic mice, while the protective effects of APNp on mitochondrial and ATF4‐CHOP apoptosis pathways were counteracted when Smad3 was activated by exogenous transforming growth factor (TGF)‐β1 treatment.

Conclusions

Our study provided the first evidence that APNp promoted neural survival following ICH injury in the diabetic setting and revealed a novel mechanism by which APNp suppressed mitochondrial and ATF4‐CHOP apoptosis pathways in a Smad3 dependent manner.

C/EBPβ and YY1 bind and interact with Smad3 to modulate lipopolysaccharide-induced amelotin gene transcription in mouse gingival epithelial cells

Junctional epithelium (JE) develops from reduced enamel epithelium during tooth formation and is critical for the maintenance of healthy periodontal tissue through ensuring appropriate immune responses and the rapid turnover of gingival epithelial cells. We have previously shown a relationship between inflammatory cytokines and expression of JE‐specific genes, such as amelotin (AMTN), in gingival epithelial cells. Here, we elucidated the effects of Porphyromonas gingivalis‐derived lipopolysaccharide (PgLPS) on Amtn gene transcription and the interaction of transcription factors. To determine the molecular basis of transcriptional regulation of the Amtn gene by PgLPS, we performed real‐time PCR and carried out luciferase assays using a mouse Amtn gene promoter linked to a luciferase reporter gene in mouse gingival epithelial GE1 cells. Gel mobility shift and chromatin immunoprecipitation assays were performed to identify response elements bound to LPS‐induced transcription factors. Next, we analyzed protein levels of the LPS‐induced transcription factors and the interaction of transcription factors by western blotting and immunoprecipitation. LPS increased Amtn mRNA levels and elevated luciferase activities of constructs containing regions between −116 and −238 of the mouse Amtn gene promoter. CCAAT/enhancer‐binding protein (C/EBP) 1–, C/EBP2– and Ying Yang 1 (YY1)–nuclear protein complexes were increased by LPS treatment. Furthermore, we identified LPS‐modulated interactions with C/EBPβ, YY1 and Smad3. These results demonstrate that PgLPS regulates Amtn gene transcription via binding of C/EBPβ–Smad3 and YY1–Smad3 complexes to C/EBP1, C/EBP2 and YY1 response elements in the mouse Amtn gene promoter.

Negative feedback by SNAI2 regulates TGFβ1-induced amelotin gene transcription in epithelial-mesenchymal transition

Junctional epithelium (JE) demonstrates biological responses with the rapid turnover of gingival epithelial cells. The state occurs in inflammation of gingiva and wound healing after periodontal therapy. To understand the underlying mechanisms and to maintain homeostasis of JE, it is important to investigate roles of JE-specific genes. Amelotin (AMTN) is localized at JE and regulated by inflammatory cytokines and apoptotic factors that represent a critical role of AMTN in stabilizing the dentogingival attachment, which is an entrance of oral bacteria. In this study, we demonstrated that the AMTN gene expression was regulated by SNAI2 and transforming growth factor β1 (TGFβ1)-induced epithelial-mesenchymal transition (EMT) that occurs in wound healing and fibrosis during chronic inflammation. SNAI2 downregulated AMTN gene expression via SNAI2 bindings to E-boxes (E2 and E4) in the mouse AMTN gene promoter in EMT of gingival epithelial cells. Meanwhile, TGFβ1-induced AMTN gene expression was attenuated by SNAI2 and TGFβ1-induced SNAI2, without inhibition of the TGFβ1-Smad3 signaling pathway. Moreover, SNAI2 small interfering RNA (siRNA) rescued SNAI2-induced downregulation of AMTN gene expression, and TGFβ1-induced AMTN gene expression was potentiated by SNAI2 siRNA. Taken together, these data demonstrated that AMTN gene expression in the promotion of EMT was downregulated by SNAI2. The inhibitory effect of AMTN gene expression was an independent feedback on the TGFβ1-Smad3 signaling pathway, suggesting that the mechanism can be engaged in maintaining homeostasis of gingival epithelial cells at JE and the wound healing phase.