A flexible loop in the paxillin LIM3 domain mediates its direct binding to integrin ß subunits.

Integrins are fundamental for cell adhesion and the formation of focal adhesions (FA). Accordingly, these receptors guide embryonic development, tissue maintenance, and haemostasis but are also involved in cancer invasion and metastasis. A detailed understanding of the molecular interactions that drive integrin activation, FA assembly, and downstream signalling cascades is critical. Here, we reveal a direct association of paxillin, a marker protein of FA sites, with the cytoplasmic tails of the integrin ß1 and ß3 subunits. The binding interface resides in paxillin's LIM3 domain, where based on the NMR structure and functional analyses, a flexible, 7-amino acid loop engages the unstructured part of the integrin cytoplasmic tail. Genetic manipulation of the involved residues in either paxillin or integrin ß3 compromises cell adhesion and motility of murine fibroblasts. This direct interaction between paxillin and the integrin cytoplasmic domain identifies an alternative, kindlin-independent mode of integrin outside-in signalling particularly important for integrin ß3 function.

ROS-mediated ITGB5 promotes tongue squamous cell carcinoma metastasis through epithelial mesenchymal transition and cell adhesion signal pathway.

PURPOSE: Integrin ß5 (ITGB5) is an integrin ß subunit member widely expressed in the human bodies, especially in cancer cells and tissues, which is a key factor in promoting tumor metastasis. In this study we investigated the differential expression of ITGB5 in tongue squamous cell carcinoma (TSCC), especially in those with lymph node metastasis, and revealed the possible mechanism. METHODS: The expression of ITGB5 in TSCC was analyzed by database and verified by immunohistochemistry through 135 TSCC patients' tissue sections from Sun Yat-sen Memorial Hospital and Guangzhou First People's Hospital. The relationship between ITGB5 and lymph node metastasis or prognosis was analyzed retrospectively. The effects of ITGB5 on TSCC cells were examined through knocking down or overexpression and its possible regulator and signal pathway were explored. RESULTS: The expression of ITGB5 in TSCC was higher than that in adjacent tissue, and the expression in patients with lymph node metastasis was higher than that in patients without lymph node metastasis. The high expression of ITGB5 predicted a worse prognosis. Knock down of ITGB5 suppressed invasion and migration of TSCC cells, while overexpression of ITGB5 contributed to invasion and migration. Reactive oxygen species (ROS) regulated epithelial mesenchymal transition (EMT), and we further verified that ROS enhanced the expression of ITGB5 to promote the metastasis of TSCC. Mechanistically, ITGB5 functions through cell adhesion signal pathway. CONCLUSION: The increased expression of ITGB5 in tongue squamous cell carcinoma with lymph node metastasis may be a potential target for evaluating lymph node metastasis and worse prognosis of tongue squamous cell carcinoma. Scavenge of ROS or knock down of ITGB5 may be the strategies to overcome metastasis of TSCC.

The integrin receptor beta7 subunit mediates airway remodeling and hyperresponsiveness in allergen exposed mice.

BACKGROUND: Fibroblast differentiation to a myofibroblast phenotype is a feature of airway remodeling in asthma. Lung fibroblasts express the integrin receptor α4ß7 and fibronectin induces myofibroblast differentiation via this receptor. OBJECTIVES: To investigate the role of the ß7 integrin receptor subunit and α4ß7 integrin complex in airway remodeling and airway hyperresponsiveness (AHR) in a murine model of chronic allergen exposure. METHODS: C57BL/6 wild type (WT) and ß7 integrin null mice (ß7 -/-) were sensitized (days 1,10) and challenged with ovalbumin (OVA) three times a week for one or 4 weeks. Similar experiments were performed with WT mice in the presence or absence of α4ß7 blocking antibodies. Bronchoalveolar (BAL) cell counts, AHR, histological evaluation, soluble collagen content, Transforming growth factor-ß (TGFß) and Interleukin-13 (IL13) were measured. Phenotype of fibroblasts cultured from WT and ß7 -/- saline (SAL) and OVA treated mice was evaluated. RESULTS: Eosinophil numbers were similar in WT vs ß7-/- mice. Prolonged OVA exposure in ß7-/- mice was associated with reduced AHR, lung collagen content, peribronchial smooth muscle, lung tissue TGFß and IL13 expression as compared to WT. Similar findings were observed in WT mice treated with α4ß7 blocking antibodies. Fibroblast migration was enhanced in response to OVA in WT but not ß7 -/- fibroblasts. α-SMA and fibronectin expression were reduced in ß7-/- fibroblasts relative to WT. CONCLUSIONS: The ß7 integrin subunit and the α4ß7 integrin complex modulate AHR and airway remodeling in a murine model of allergen exposure. This effect is, at least in part, explained by inhibition of fibroblast activation and is independent of eosinophilic inflammation.

CRISPR/Cas9-mediated knock out of ITGB6 in human OSCC cells reduced migration and proliferation ability.

BACKGROUND: The treatment of oral squamous cell carcinoma (OSCC) remains challenging and survival rates have not been improved significantly over the past decades. Integrins have been recognized driving the cancer progression and high expression levels cause poor outcomes in patients afflicted with OSCC. Integrin αvß6 and its subunit integrin beta 6 (ITGB6) were discovered to enhance the invasiveness by providing beneficial effects on downstream pathways promoting the cancer progression. The objective of this study was to establish a CRISPR/Cas9-mediated knock out of ITGB6 in the human OSCC cell line HN and investigate the effects on the migration and proliferation ability. METHODS: ITGB6 knock out was performed using the CRISPR/Cas9-system, RNPs, and lipofection. Monoclonal cell clones were achieved by limiting dilution and knock out verification was carried out by sanger sequencing and FACS on protein level. The effects of the knock out on the proliferation and migration ability were evaluated by using MTT and scratch assays. In addition, in silico TCGA analysis was utilized regarding the effects of ITGB6 on overall survival and perineural invasion. RESULTS: In silico analysis revealed a significant impact of ITGB6 mRNA expression levels on the overall survival of patients afflicted with OSCC. Additionally, a significantly higher rate of perineural invasion was discovered. CRISPR/Cas9-mediated knock out of ITGB6 was performed in the OSCC cell line HN, resulting in the generation of a monoclonal knock out clone. The knock out clone exhibited a significantly reduced migration and proliferation ability when compared to the wildtype. CONCLUSIONS: ITGB6 is a relevant factor in the progression of OSCC and can be used for the development of novel treatment strategies. The present study is the first to establish a monoclonal CRISPR/Cas9-mediated ITGB6 knockout cell clone derived from an OSCC cell line. It suggests that ITGB6 has a significant impact on the proliferative and migratory capacity in vitro.

Synthetic integrin antibodies discovered by yeast display reveal αV subunit pairing preferences with ß subunits.

Integrins are cell surface receptors that mediate the interactions of cells with their surroundings and play essential roles in cell adhesion, migration, and homeostasis. Eight of the 24 integrins bind to the tripeptide Arg-Gly-Asp (RGD) motif in their extracellular ligands, comprising the RGD-binding integrin subfamily. Despite similarity in recognizing the RGD motif and some redundancy, these integrins can selectively recognize RGD-containing ligands to fulfill specific functions in cellular processes. Antibodies against individual RGD-binding integrins are desirable for investigating their specific functions, and were selected here from a synthetic yeast-displayed Fab library. We discovered 11 antibodies that exhibit high specificity and affinity toward their target integrins, i.e. αVß3, αVß5, αVß6, αVß8, and α5ß1. Of these, six are function-blocking antibodies and contain a ligand-mimetic R(G/L/T)D motif in their CDR3 sequences. We report antibody-binding specificity, kinetics, and binding affinity for purified integrin ectodomains, as well as intact integrins on the cell surface. We further used these antibodies to reveal binding preferences of the αV subunit for its 5 ß-subunit partners: ß6 = ß8 > ß3 > ß1 = ß5.

ITGB5 facilitates gastric cancer metastasis by promoting TGFBR2 endosomal recycling.

TGFBR2, a key regulator of the TGFß signaling pathway, plays a crucial role in gastric cancer (GC) metastasis through its endosomal recycling process. Despite its importance, the mechanisms governing this process remain unclear. Here, we identify integrin ß5 (ITGB5) as a critical mediator that promotes TGFBR2 endosomal recycling. Our study reveals elevated expression of ITGB5 in GC, particularly in metastatic cases, correlating with poor patient outcomes. Knockdown of ITGB5 impairs GC cell metastasis both in vitro and in vivo. Mechanistically, ITGB5 facilitates epithelial-mesenchymal transition mediated by TGFß signaling, thereby enhancing GC metastasis. Acting as a scaffold, ITGB5 interacts with TGFBR2 and SNX17, facilitating SNX17-mediated endosomal recycling of TGFBR2 and preventing lysosomal degradation, thereby maintaining its surface distribution on tumor cells. Notably, TGFß signaling directly upregulates ITGB5 expression, establishing a positive feedback loop that exacerbates GC metastasis. Our findings shed light on the role of ITGB5 in promoting GC metastasis through SNX17-mediated endosomal recycling of TGFBR2, providing insights for the development of targeted cancer therapies.

Sevoflurane blocks KLF5-mediated transcriptional activation of ITGB2 to inhibit macrophage infiltration in hepatic ischemia/reperfusion injury.

BACKGROUND: Sevoflurane (Sevo) preconditioning and postconditioning play a protective role against injury induced by hepatic ischemia/reperfusion (I/R). At the same time, the involvement of macrophage infiltration in this process and the precise mechanisms are unclear. Here, we designed this research to elucidate the protective effects of Sevo against hepatic I/R injury and the molecules involved. METHODS: The alleviating effect of Sevo on the liver injury was analyzed by liver function analysis, hematoxylin and eosin staining, Masson trichrome staining, terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling, western blot analysis and an enzyme-linked immunosorbent assay. An in vitro cell model was developed using alpha mouse liver 12 (AML12) cells, and the cell model was treated with oxygen-glucose deprivation and reoxygenation and Sevo. Multiple bioinformatics databases were used to screen transcriptional regulators related to hepatic I/R injury and the targets of Krueppel-like factor 5 (KLF5). KLF5 expression was artificially upregulated alone or with integrin beta-2 (ITGB2) knockdown to substantiate their involvement in Sevo-mediated hepatoprotection. RESULTS: Sevo protected the liver against I/R injury by reducing cell apoptosis and inflammatory response. KLF5 was upregulated in liver tissues following I/R injury, whereas KLF5 overexpression aggravated macrophage infiltration and liver injury induced by I/R injury. KLF5 bound to the promoter of ITGB2 to enhance ITGB2 transcription. Knockdown of ITGB2 reversed the aggravation of injury caused by KLF5 overexpression in mice and AML12 cells. CONCLUSIONS: Sevo blocked KLF5-mediated transcriptional activation of ITGB2, thereby inhibiting macrophage infiltration in hepatic I/R injury.

The protective roles of integrin α4ß7 and Amphiregulin-expressing innate lymphoid cells in lupus nephritis.

Type 2 innate lymphoid cells (ILC2s) have emerged as key regulators of the immune response in renal inflammatory diseases such as lupus nephritis. However, the mechanisms underlying ILC2 adhesion and migration in the kidney remain poorly understood. Here, we revealed the critical role of integrin α4ß7 in mediating renal ILC2 adhesion and function. We found that integrin α4ß7 enables the retention of ILC2s in the kidney by binding to VCAM-1, E-cadherin, or fibronectin on structural cells. Moreover, integrin α4ß7 knockdown reduced the production of the reparative cytokine amphiregulin (Areg) by ILC2s. In lupus nephritis, TLR7/9 signaling within the kidney microenvironment downregulates integrin α4ß7 expression, leading to decreased Areg production and promoting the egress of ILC2s. Notably, IL-33 treatment upregulated integrin α4ß7 and Areg expression in ILC2s, thereby enhancing survival and reducing inflammation in lupus nephritis. Together, these findings highlight the potential of targeting ILC2 adhesion as a therapeutic strategy for autoimmune kidney diseases.

The ADAM17 inhibitor ZLDI-8 sensitized hepatocellular carcinoma cells to sorafenib through Notch1-integrin ß-talk.

ZLDI-8 is an A disintegrin and metalloproteinase domain 17 (ADAM17) inhibitor that suppresses the shedding of Notch1 to the Notch1 intracellular domain (NICD). In previous studies, we found that ZLDI-8 was able to sensitize HCC to sorafenib, but the mechanism of action remains unclear. The sensitizing effects of ZLDI-8 were tested both in vitro and in vivo. EMT-related factors, sorafenib sensitivity-related proteins and ECM-related gene expression were assessed using immunohistochemistry, RTPCR and Western blotting. Knockdown assays were conducted to determine the relationship between the Notch and Integrin pathways. CoIP assays, nuclear and cytoplasmic fractionation and immunofluorescence colocalization were applied to explore the interaction between the Notch and Integrin pathways. Appropriate statistical analysis methods were used to assess the significance of the experimental results and to ensure the scientific validity and reliability of the experimental design. We found that ECM- and EMT-related proteins were downregulated after ZLDI-8 treatment (P<0.05). ZLDI-8 significantly downregulated Integrinß1 and Integrinß3 in HCC in vitro and in vivo (P<0.05), possibly through Foxc2-dependent regulation. Mechanistically, interfering with the expression of both Integrin-linked kinase (ILK) and the NICD may downregulate the expression of proteins targeted by sorafenib, thereby sensitizing cells to sorafenib. The retroregulation of Integrinß by ILK may occur through the interaction between the NICD and ILK and may be the result of the translocation of the complexus. Our study indicates that blocking the Notch pathway may affect Integrinß through crosstalk between the Notch1 and Integrinß/ILK signaling pathways, thus providing a potential therapeutic strategy for HCC.

Super-enhancer-driven LIF promotes the mesenchymal transition in glioblastoma by activating ITGB2 signaling feedback in microglia.

BACKGROUND: The mesenchymal (MES) subtype of glioblastoma (GBM) is believed to be influenced by both cancer cell-intrinsic alterations and extrinsic cellular interactions, yet the underlying mechanisms remain unexplored. METHODS: Identification of microglial heterogeneity by bioinformatics analysis. Transwell migration, invasion assays, and tumor models were used to determine gene function and the role of small molecule inhibitors. RNA sequencing, chromatin immunoprecipitation, and dual-luciferase reporter assays were performed to explore the underlying regulatory mechanisms. RESULTS: We identified the inflammatory microglial subtype of tumor-associated microglia (TAM) and found that its specific gene integrin beta 2 (ITGB2) was highly expressed in TAM of MES GBM tissues. Mechanistically, the activation of ITGB2 in microglia promoted the interaction between the SH2 domain of STAT3 and the cytoplasmic domain of ITGB2, thereby stimulating the JAK1/STAT3/IL-6 signaling feedback to promote the MES transition of GBM cells. Additionally, microglia communicated with GBM cells through the interaction between the receptor ITGB2 on microglia and the ligand ICAM-1 on GBM cells, while an increased secretion of ICAM-1 was induced by the proinflammatory cytokine leukemia inhibitory factor (LIF). Further studies demonstrated that inhibition of cyclin-dependent kinase 7 substantially reduced the recruitment of SNW1 to the super-enhancer of LIF, resulting in transcriptional inhibition of LIF. We identified notoginsenoside R1 as a novel LIF inhibitor that exhibited synergistic effects in combination with temozolomide. CONCLUSIONS: Our research reveals that the epigenetic-mediated interaction of GBM cells with TAM drives the MES transition of GBM and provides a novel therapeutic avenue for patients with MES GBM.

ITGB6 promotes pancreatic fibrosis and aggravates the malignant process of pancreatic cancer via JAK2/STAT3 signaling pathway.

Integrin ß6 (ITGB6) is upregulated in multiple tumor types and elevated ITGB6 levels have been detected in patients with chronic pancreatitis. However, the role of ITGB6 in pancreatic fibrosis and cancer remains to be elucidated. In the present study, ITGB6 expression was assessed using western blotting and qRT-PCR. Besides, cell proliferation, cycling, migration, and invasion were evaluated using CCK-8, flow cytometry, wound healing, and transwell assays, respectively. The expression of fibrosis and JAK2/STAT3 signaling markers was detected by western blotting and immunofluorescence analysis. Moreover, nude mice were subcutaneously injected with co-cultured cell suspensions to establish an in vivo model. The results showed that ITGB6 was highly expressed in pancreatic cancer tissues and TGF-ß-induced pancreatic stellate cells (PSCs). Inhibition of ITGB6 expression in PSCs resulted in clear inhibition of activated PSC proliferation, migration, and fibrogenesis. Additionally, reduced ITGB6 expression inhibits the JAK2/STAT3 signaling pathway. Interestingly, activators of the JAK2/STAT3 signaling pathway reversed the effects of ITGB6 disruption on PSCs. Activated PSCs notably promoted the proliferation, invasion, and migration of pancreatic cancer cells in a co-culture assay. In contrast, activated PSCs with low ITGB6 expression failed to significantly affect the malignancy of pancreatic cancer cells. Moreover, in vivo results showed that interference with ITGB6 inhibited the activation of PSCs and promoted the development of pancreatic cancer. Silencing ITGB6 inhibited the proliferation, migration, and fibrosis-like effects of activated PSCs and indirectly inhibited the metastasis and malignant process of pancreatic cancer by inhibiting the JAK2/STAT3 signaling pathway. Therefore, ITGB6 is a potential candidate target for pancreatic cancer prevention and treatment.

Exploring the role of ITGB6: fibrosis, cancer, and other diseases.

Integrin ß6 (ITGB6), a member of the integrin family of proteins, is only present in epithelial tissues and frequently associates with integrin subunit αv to form transmembrane heterodimers named integrin αvß6. Importantly, ITGB6 determines αvß6 expression and availability. In addition to being engaged in organ fibrosis, ITGB6 is also directly linked to the emergence of cancer, periodontitis, and several potential genetic diseases. Therefore, it is of great significance to study the molecular-biological mechanism of ITGB6, which could provide novel insights for future clinical diagnosis and therapy. This review introduces the structure, distribution, and biological function of ITGB6. This review also expounds on ITGB6-related diseases, detailing the known biological effects of ITGB6.

CircItgb5 promotes synthetic phenotype of pulmonary artery smooth muscle cells via interacting with miR-96-5p and Uba1 in monocrotaline-induced pulmonary arterial hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare but fatal cardiopulmonary disease mainly characterized by pulmonary vascular remodeling. Aberrant expression of circRNAs has been reported to play a crucial role in pulmonary vascular remodeling. The existing literature predominantly centers on studies that examined the sponge mechanism of circRNAs. However, the mechanism of circRNAs in regulating PAH-related protein remains largely unknown. This study aimed to investigate the effect of circItgb5 on pulmonary vascular remodeling and the underlying functional mechanism. MATERIALS AND METHODS: High-throughput circRNAs sequencing was used to detect circItgb5 expression in control and PDGF-BB-treated pulmonary arterial smooth muscle cells (PASMCs). Localization of circItgb5 in PASMCs was determined via the fluorescence in situ hybridization assay. Sanger sequencing was applied to analyze the circularization of Itgb5. The identification of proteins interacting with circItgb5 was achieved through a RNA pull-down assay. To assess the impact of circItgb5 on PASMCs proliferation, an EdU assay was employed. Additionally, the cell cycle of PASMCs was examined using a flow cytometry assay. Western blotting was used to detect biomarkers associated with the phenotypic switch of PASMCs. Furthermore, a monocrotaline (MCT)-induced PAH rat model was established to explore the effect of silencing circItgb5 on pulmonary vascular remodeling. RESULTS: CircItgb5 was significantly upregulated in PDGF-BB-treated PASMCs and was predominately localized in the cytoplasm of PASMCs. In vivo experiments revealed that the knockdown of circItgb5 attenuated MCT-induced pulmonary vascular remodeling and right ventricular hypertrophy. In vitro experiments revealed that circItgb5 promoted the transition of PASMCs to synthetic phenotype. Mechanistically, circItgb5 sponged miR-96-5p to increase mTOR level and interacted with Uba1 protein to activate the Ube2n/Mdm2/ACE2 pathway. CONCLUSIONS: CircItgb5 promoted the transition of PASMCs to synthetic phenotype by interacting with miR-96-5p and Uba1 protein. Knockdown of circItgb5 mitigated pulmonary arterial pressure, pulmonary vascular remodeling and right ventricular hypertrophy. Overall, circItgb5 has the potential for application as a therapeutic target for PAH.

Upregulation of ITGB6 in primary palmar hyperhidrosis.

BACKGROUND: The regulatory effect of integrin ß6 (ITGB6) on sweat gland cells in primary palmar hyperhidrosis (PPH) remains unclear. OBJECTIVES: This study investigated the involvement of ITGB6 in the pathogenesis of PPH. MATERIAL AND METHODS: Sweat gland tissues were collected from PPH patients and healthy volunteers. The expression levels of ITGB6 in sweat gland tissues were detected with quantitative polymerase chain reaction (qPCR), western blot and immunohistochemical staining. Sweat gland cells were extracted from PPH patients, and identified with immunofluorescence staining of CEA and CK7. The expression of aquaporin 5 (AQP5) and Na-K-Cl cotransporter 1 (NKCC1) in primary sweat gland cells that overexpress ITGB6 were also detected. Through a series of bioinformatic methods, differentially expressed genes in sweat gland tissues were examined and validated via comparing PPH samples and controls. The key proteins and biological functions enriched in PPH were determined using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. RESULTS: The ITGB6 was upregulated in sweat gland tissues of PPH patients compared to that of healthy volunteers. The CEA and CK7 were positively expressed in sweat gland cells extracted from PPH patients. The overexpression of ITGB6 upregulated AQP5 and NKCC1 protein expression in the sweat gland cells of PPH patients. A total of 562 differentially expressed mRNAs were identified using high-throughput sequencing (394 upregulated, 168 downregulated), which were mainly active in the chemokine and Wnt signaling pathways. After verification with qPCR and western blot, the overexpression of ITGB6 significantly upregulated CXCL3, CXCL5, CXCL10, and CXCL11, and downregulated Wnt2 mRNA and protein expression in sweat gland cells. CONCLUSIONS: The ITGB6 is upregulated in PPH patients. It may be involved in the pathogenesis of PPH by upregulating AQP5, NKCC1, CXCL3, CXCL5, CXCL10, and CXCL11, and downregulating Wnt2 expression in sweat glands.

Integrin subunit beta 8 contributes to lenvatinib resistance in HCC.

Lenvatinib is a multikinase inhibitor approved as a first-line therapy for advanced hepatocellular carcinoma (HCC). However, the development of drug resistance is common, and the underlying mechanisms governing this resistance are largely unknown. In this study, we established two lenvatinib-resistant (LR) HCC cell lines and identified integrin subunit beta 8 (ITGB8) as a critical contributor to lenvatinib resistance in HCC. The elevated expression of ITGB8 was observed in LR HCC cells. Furthermore, silencing of ITGB8 reversed lenvatinib resistance in vitro and in vivo, whereas ectopic expression of ITGB8 in lenvatinib-sensitive parental HCC cells exhibited increased resistance to lenvatinib. Mechanistically, ITGB8 regulated lenvatinib resistance through an HSP90-mediated stabilization of AKT and enhanced AKT signaling. In support of this model, either an AKT inhibitor MK-2206 or an HSP90 inhibitor 17-AAG resensitized LR HCC cells to lenvatinib treatment. Conclusion: Collectively, our results establish a crucial role of ITGB8 in lenvatinib resistance, and suggest that targeting the ITGB8/HSP90/AKT axis is a promising therapeutic strategy in patients with HCC exhibiting lenvatinib resistance.

The Alleviating Effect of Lagerstroemia indica Flower Extract on Stretch Marks through Regulation of Mast Cells.

Striae distensae (SD) or stretch marks are common linear scars of atrophic skin with disintegrating extracellular matrix (ECM) structures. Although fibroblasts contribute to the construction of ECM structure in SD, some studies have reported that mast cell degranulation causes the disruption of ECM in early SD lesions. Lagerstroemia indica flower (LIF) has traditionally been used in India as a diuretic. However, little is known about the effect and molecular action of Lagerstroemia indica flower extract (LIFE) on alleviating SD. This study evaluated the effects of LIFE on mast cell degranulation and the synthesis of ECM components in fibroblasts. LIFE inhibits the adhesion of rat basophilic leukemia (RBL) cells, RBL-2H3 on fibronectin (FN) and the expression of integrin, a receptor for FN, thereby reducing focal adhesion kinase (FAK) phosphorylation. In addition, LIFE attenuated the allergen-induced granules and cytokine interleukin 3 (IL-3) through the adhesion with FN. Moreover, the conditioned medium (CM) of activated mast cells decreases the synthesis of ECM components, and LIFE restores the abnormal expressions induced by activated mast cells. These results demonstrate that LIFE suppresses FN-induced mast cell activation and promotes the synthesis of ECM components in fibroblast, which indicates that LIFE may be a useful cosmetic agent for SD treatment.

The ß8 integrin cytoplasmic domain activates extracellular matrix adhesion to promote brain neurovascular development.

In the developing mammalian brain, neuroepithelial cells interact with blood vessels to regulate angiogenesis, blood-brain barrier maturation and other key neurovascular functions. Genetic studies in mice have shown that neurovascular development is controlled, in part, by Itgb8, which encodes the neuroepithelial cell-expressed integrin ß8 subunit. However, these studies have involved complete loss-of-function Itgb8 mutations, and have not discerned the relative roles for the ß8 integrin extracellular matrix (ECM) binding region versus the intracellular signaling tail. Here, Cre/lox strategies have been employed to selectively delete the cytoplasmic tail of murine Itgb8 without perturbing its transmembrane and extracellular domains. We report that the ß8 integrin cytoplasmic domain is essential for inside-out modulation of adhesion, including activation of latent-TGFßs in the ECM. Quantitative sequencing of the brain endothelial cell transcriptome identifies TGFß-regulated genes with putative links to blood vessel morphogenesis, including several genes linked to Wnt/ß-catenin signaling. These results reveal that the ß8 integrin cytoplasmic domain is essential for the regulation of TGFß-dependent gene expression in endothelial cells and suggest that cross-talk between TGFßs and Wnt pathways is crucial for neurovascular development.

Integrin αvß6 contributes to the development of intestinal fibrosis via the FAK/AKT signaling pathway.

Intestinal fibrosis is one of the most severe complications of inflammatory bowel disease (IBD) and frequently requires surgery due to intestinal obstruction. Integrin αvß6, which is mainly regulated by the integrin ß6 subunit gene (ITGB6), is a special integrin subtype expressed only in epithelial cells. In our previous study, we found integrin αvß6 can promote the development of IBD, but the role of integrin αvß6 in intestinal fibrosis remains unclear. In this study, we observed a gradual increase of ITGB6 mRNA expression from normal region to stenotic region of IBD patients' intestinal specimens. Next, we established a dextran sulfate sodium (DSS)-induced intestinal fibrosis model and a heterotopic intestinal transplant model, and found intestinal fibrosis was decreased in ITGB6-deficient mice compared to wild-type (WT) mice. Furthermore, we performed RNA-sequencing and KEGG pathway analysis on intestinal tissues from ITGB6-overexpressing transgenic mice and WT mice, and found multiple pathways containing ITGB6, are related to the activation of focal adhesion kinase (FAK); finding was confirmed by Western blot. At last, we generated a heterotopic intestinal transplant model found the FAK/AKT pathway was inhibited in ITGB6-deficient mice. In conclusion, our data demonstrate that integrin αvß6 promotes the pathogenesis of intestinal fibrosis by FAK/AKT pathway, making integrin αvß6 a potential therapeutic target to prevent this condition.

Peri-implantation expression and regulation of ITGB8 in goat uterus.

Ruminants have a superficial implantation pattern. The extended conceptus attaches to the receptive endometrium to form the cotyledonary placenta. During the attachment, a large number of events occur at the maternal-fetal interface. However, the related molecular mechanisms have not been fully understood. Integrin beta8 (ITGB8) is a subunit of integrin beta involved in embryo implantation. In this study, we determined peri-implantation expression and regulation of ITGB8 in goat uterus. The mRNA and protein levels of ITGB8 were both high in goat endometrial luminal epithelium (LE) and superficial glandular epithelium (sGE) during the adhesion period (Days 16-19 of pregnancy). Such expression profile was opposite to that of microRNA-187 (miR-187). Then, we validated that miR-187 targeted the 3' untranslated region (UTR) of ITGB8 in primary goat endometrial epithelial cells (EECs). In EECs, inhibition of miR-187 resulted in not only up-regulated ITGB8 level but also reduced cell proliferation and focal adhesion kinase (FAK) activity. Moreover, ITGB8 and miR-187 were regulated by interferon tau (IFNT). Altogether, in goat, the miR-187/ITGB8 axis may be involved in conceptus attachment and is downstream of IFNT. Our results will help us better understand the mechanisms of ruminant implantation and may provide a useful tool to improve the reproduction ratio for ruminants.

Antibody secreting cells are critically dependent on integrin α4ß7/MAdCAM-1 for intestinal recruitment and control of the microbiota during chronic colitis.

T and B cells employ integrin α4ß7 to migrate to intestine under homeostatic conditions. Whether those cells differentially rely on α4ß7 for homing during inflammatory conditions has not been fully examined. This may have implications for our understanding of the mode of action of anti-integrin therapies in inflammatory bowel disease (IBD). Here, we examined the role of α4ß7 integrin during chronic colitis using IL-10-/- mice, ß7-deficient IL-10-/-, IgA-deficient IL-10-/- mice, and antibody blockade of MAdCAM-1. We found that α4ß7 was predominantly expressed by B cells. ß7 deficiency and MAdCAM-1 blockade specifically depleted antibody secreting cells (ASC) (not T cells) from the colonic LP, leading to a fecal pan-immunoglobulin deficit, severe colitis, and alterations of microbiota composition. Colitis was not due to defective regulation, as dendritic cells (DC), regulatory T cells, retinaldehyde dehydrogenase (RALDH) expression, activity, and regulatory T/B-cell cytokines were all comparable between the strains/treatment. Finally, an IgA deficit closely recapitulated the clinical phenotype and altered microbiota composition of ß7-deficient IL-10-/- mice. Thus, a luminal IgA deficit contributes to accelerated colitis in the ß7-deficient state. Given the critical/nonredundant dependence of IgA ASC on α4ß7:MAdCAM-1 for intestinal homing, B cells may represent unappreciated targets of anti-integrin therapies.