Integrins and their potential roles in mammalian pregnancy

Integrins are a highly complex family of receptors that, when expressed on the surface of cells, can mediate reciprocal cell-to-cell and cell-to-extracellular matrix(ECM) interactions leading to assembly of integrin adhesion complexes(IACs) that initiate many signaling functions both at the membrane and deeper within the cytoplasm to coordinate processes including cell adhesion, migration, proliferation, survival, differentiation, and metabolism. All metazoan organisms possess integrins, and it is generally agreed that integrins were associated with the evolution of multicellularity, being essential for the association of cells with their neighbors and surroundings, during embryonic development and many aspects of cellular and molecular biology. Integrins have important roles in many aspects of embryonic development, normal physiology, and disease processes with a multitude of functions discovered and elucidated for integrins that directly influence many areas of biology and medicine, including mammalian pregnancy, in particular implantation of the blastocyst to the uterine wall, subsequent placentation and conceptus(embryo/fetus and associated placental membranes) development. This review provides a succinct overview of integrin structure, ligand binding, and signaling followed with a concise overview of embryonic development, implantation, and early placentation in pigs, sheep, humans, and mice as an example for rodents. A brief timeline of the initial localization of integrin subunits to the uterine luminal epithelium(LE) and conceptus trophoblast is then presented, followed by sequential summaries of integrin expression and function during gestation in pigs, sheep, humans, and rodents. As appropriate for this journal, summaries of integrin expression and function during gestation in pigs and sheep are in depth, whereas summaries for humans and rodents are brief. Because similar models to those illustrated in Fig. 1, 2, 3, 4, 5 and 6 are present throughout the scientific literature, the illustrations in this manuscript are drafted as Viking imagery for entertainment purposes.

CD44v6、MMP_2和β_1integrins在CINⅡ-Ⅲ、宫颈鳞形细胞癌中的表达和意义

目的通过研究CD44v6、MMP2和β1integrins在CINⅡ-Ⅲ、宫颈鳞形细胞癌组织中的表达,探讨细胞外基质降解在宫颈鳞形细胞癌发生发展中的作用。方法收集宫颈鳞形细胞癌组织切片20例,CINⅡ-Ⅲ组织切片15例,正常宫颈组织切片10例,免疫组化法检测CD44v6、MMP2和β1integrins表达。结果CD44v6低表达与CINⅡ-Ⅲ病变有相关性(P<0.05),与宫颈鳞形上皮癌变有高度相关性(P<0.001);β1integrins低表达与CINⅡ-Ⅲ病变有高度相关性(P<0.001);MMP2高表达与宫颈鳞形上皮癌变有高度相关性(P<0.001),但与CINⅡ-Ⅲ病变无相关性(P>0.05)。结论CD44v6、β1integrins和MMP2的异常表达与宫颈鳞癌的发生发展有关,细胞外基质作用减弱有利于宫颈癌变的发生,其本身结构的破坏有利于宫颈癌的浸润。

Mechanochemistry of catch bonds between integrins and ligands

Integrins are a large family of adhesion molecules broadly expressed on the surface of a wide variety of cells as heterodimers.Binding of integrins to ligands provides anchorage and signals for the cell,making them prime candidates for mechanosensing molecules.To elucidate how force regulates integrin/ligand dissociation,we used molecular mechanics experiments

Effects of Integrins and Integrin αvβ3 Inhibitor on Angiogenesis in Cerebral Ischemic Stroke

Summary： Integrins such as αvβ3, α5β31 play a key role in angiogenesis regulation, invasion and metastasis, inflammation, wound healing, etc. The up-regulation of integrin αvβ3 after cerebral ischemic stroke can promote angiogenesis, which in turn improves functional recovery. In addition, the integrin αvβ3 inhibitor can block the blood-brain barrier （BBB） leakage induced by vascular endothelial growth factor （VEGF） and also can reduce inflammatory reaction, decrease the deposition of fibrinogen. Other studies showed that integrin αvβ3 is not essential in revascularization. Therefore, the effect of integrin αvβ3 in the whole process of brain function recovery merits further study.

Roles for α_Vβ_3 and GP Ilb/Illa integrins in MDA-MB-231cell invasion and shear flow-induced mechanotransduction

Introduction Hematogenous metastasis is the mainly leading cause of death in breast carcinoma patients.A better understanding of the underlying molecular and cellular mechanisms is crucial for the development of effective treatment for metastatic breast cancer[1].It has been well established that cell adhesion and invasion is mediated by a variety of transmembrane proteins,including integrins,cadherins,selectins,and intercellular adhesion molecules.Among these adhesion molecules,the integrins and their downstream signaling pathways have been extensively studied[2].On the other hand,the specific events determining tumor cell interactions with endo-

Multi-scale molecular dynamics simulations and applications on mechanosensitive proteins of integrins

Molecular dynamics simulation(MDS)is a powerful technology for investigating evolution dynamics of target proteins,and it is used widely in various fields from materials to biology.This mini-review introduced the principles,main preforming procedures,and advances of MDS,as well as its applications on the studies of conformational and allosteric dynamics of proteins especially on that of the mechanosensitive integrins.Future perspectives were also proposed.This review could provide clues in understanding the potentiality of MD simulations in structure–function relationship investigation of biological proteins.

Changes of β_3 Integrins and Extracellular Matrix Proteins in the Endometrium of Unexplained Infertility

The purpose of this study was to investigate changes of β 3 integrins and extra cellular matrix proteins including fibronectin (FN), laminin (LN) and collagen type Ⅳ (CL typeⅣ) on the endometrium of secretory phase from 31 fertile women (fertility group)and 34 women with unexplained infertility (infertility group) by a histochemical method.The results were as follows:In glandular epithelium, β 3 integrin appeared in the mid secretory phase and continued to late secretory phase in the fertility group, but was not expressed during the secretory phase in the infertility group. Extracellular matrix proteins from the fertility group were expressed more strongly in mid secretory phase than that in the early secretory phase, and were weakest in the late secretory phase. Compared with the fertility group, the levels of extracellular matrix proteins in the infertility group were elevated in the secretory phase. In conclusion: our current study demonstrate that β 3 integrin and extracellular matrix proteins are expressed at different levels in the endometrium during the menstrual cycle. They are involved in endometrial changes during the menstrual cycle and during the implantation of the blastocyst. Their unusual expression result in the failure of implantation.

Integrins in human hepatocellular carcinoma tumorigenesis and therapy

Integrins are a family of transmembrane receptors that connect the extracellular matrix and actin skeleton, which mediate cell adhesion, migration, signal transduction, and gene transcription. As a bi-directional signaling molecule, integrins can modulate many aspects of tumorigenesis, including tumor growth, invasion, angiogenesis, metastasis, and therapeutic resistance. Therefore, integrins have a great potential as antitumor therapeutic targets. In this review, we summarize the recent reports of integrins in human hepatocellular carcinoma (HCC), focusing on the abnormal expression, activation, and signaling of integrins in cancer cells as well as their roles in other cells in the tumor microenvironment. We also discuss the regulation and functions of integrins in hepatitis B virus-related HCC. Finally, we update the clinical and preclinical studies of integrin-related drugs in the treatment of HCC.

电针联合阿仑膦酸钠对骨质疏松大鼠Integrinα2/FAK/Runx2通路的影响

目的探讨电针联合阿仑膦酸钠对去卵巢大鼠骨质疏松症的改善作用及对Integrinα2/FAK/Runx2通路调节作用。方法选取30只大鼠随机分为假手术组(6只)及造模组(24只),采用手术切除卵巢法建立骨质疏松症大鼠模型。将造模后的大鼠随机分为骨质疏松模型组、电针治疗组、阿仑膦酸钠组及联合治疗组,每组6只。电针治疗组、阿仑膦酸钠组及联合治疗组分别按照相应干预方法干预8周。通过酶联免疫吸附(ELISA)试剂盒测定大鼠血清碱性磷酸酶(ALP)、骨钙素(BGP)、抗酒石酸酸性磷酸酶(TRACP)-5b、Ⅰ型胶原羧基末端肽(ICIP)、I型胶原氨基端延长肽(PINP)水平;双能X射线测定大鼠股骨骨密度及骨矿物含量;骨生物力学测定仪测定大鼠骨生物力学指标;苏木精-伊红(HE)染色法检查股骨组织病理学变化;实时定量聚合酶链式反应(RT-qPCR)测定股骨组织Integrinα2、FAK及Runx2 mRNA水平;免疫印记法(Western blot)测定股骨组织Integrinα2、FAK及Runx2蛋白水平。结果与假手术组比较,骨质疏松模型组血清ALP、BGP、TRACP-5b、ICIP、PINP水平显著升高(P<0.05),骨密度、骨矿物含量、最大载荷、最大应力、刚度,股骨组织Integrinα2、FAK及Runx2 mRNA及蛋白水平显著降低(P<0.05);与骨质疏松模型组比较,电针治疗组、阿仑膦酸钠组及联合治疗组血清ALP、BGP、TRACP-5b、ICIP、PINP水平显著降低(P<0.05),骨密度、骨矿物含量、最大载荷、最大应力、刚度,股骨组织Integrinα2、FAK及Runx2 mRNA及蛋白水平显著升高(P<0.05);与电针治疗组及阿仑膦酸钠组比较,联合治疗组血清ALP、BGP、TRACP-5b、ICIP、PINP水平显著降低(P<0.05),骨密度、骨矿物含量、最大载荷、最大应力、刚度,股骨组织Integrinα2、FAK及Runx2 mRNA及蛋白水平显著升高(P<0.05)。结论电针联合阿仑膦酸钠能够显著提高绝经后骨质疏松症大鼠骨密度,抑制骨质疏松病理进展,改善大鼠骨代谢及骨生物力学改变,其机制可能与调节Integrinα2/FAK/Runx2通路有关。

Impacts of PI3K/protein kinase B pathway activation in reactive astrocytes: from detrimental effects to protective functions

Astrocytes are the most abundant type of glial cell in the central nervous system.Upon injury and inflammation,astrocytes become reactive and undergo morphological and functional changes.Depending on their phenotypic classification as A1 or A2,reactive astrocytes contribute to both neurotoxic and neuroprotective responses,respectively.However,this binary classification does not fully capture the diversity of astrocyte responses observed across different diseases and injuries.Transcriptomic analysis has revealed that reactive astrocytes have a complex landscape of gene expression profiles,which emphasizes the heterogeneous nature of their reactivity.Astrocytes actively participate in regulating central nervous system inflammation by interacting with microglia and other cell types,releasing cytokines,and influencing the immune response.The phosphoinositide 3-kinase(PI3K)/protein kinase B(AKT)signaling pathway is a central player in astrocyte reactivity and impacts various aspects of astrocyte behavior,as evidenced by in silico,in vitro,and in vivo results.In astrocytes,inflammatory cues trigger a cascade of molecular events,where nuclear factor-κB serves as a central mediator of the pro-inflammatory responses.Here,we review the heterogeneity of reactive astrocytes and the molecular mechanisms underlying their activation.We highlight the involvement of various signaling pathways that regulate astrocyte reactivity,including the PI3K/AKT/mammalian target of rapamycin(mTOR),αvβ3 integrin/PI3K/AKT/connexin 43,and Notch/PI3K/AKT pathways.While targeting the inactivation of the PI3K/AKT cellular signaling pathway to control reactive astrocytes and prevent central nervous system damage,evidence suggests that activating this pathway could also yield beneficial outcomes.This dual function of the PI3K/AKT pathway underscores its complexity in astrocyte reactivity and brain function modulation.The review emphasizes the importance of employing astrocyte-exclusive models to understand their functions accurately and these models are essential for clarifying astrocyte behavior.The findings should then be validated using in vivo models to ensure real-life relevance.The review also highlights the significance of PI3K/AKT pathway modulation in preventing central nervous system damage,although further studies are required to fully comprehend its role due to varying factors such as different cell types,astrocyte responses to inflammation,and disease contexts.Specific strategies are clearly necessary to address these variables effectively.

Milk fat globule epidermal growth factor 8 alleviates liver injury in severe acute pancreatitis by restoring autophagy flux and inhibiting ferroptosis in hepatocytes

BACKGROUND Liver injury is common in severe acute pancreatitis(SAP).Excessive autophagy often leads to an imbalance of homeostasis in hepatocytes,which induces lipid peroxidation and mitochondrial iron deposition and ultimately leads to ferroptosis.Our previous study found that milk fat globule epidermal growth factor 8(MFG-E8)alleviates acinar cell damage during SAP via binding toαvβ3/5 integrins.MFG-E8 also seems to mitigate pancreatic fibrosis via inhibiting chaperone-mediated autophagy.AIM To speculate whether MFG-E8 could also alleviate SAP induced liver injury by restoring the abnormal autophagy flux.METHODS SAP was induced in mice by 2 hly intraperitoneal injections of 4.0 g/kg L-arginine or 7 hly injections of 50μg/kg cerulein plus lipopolysaccharide.mfge8-knockout mice were used to study the effect of MFG-E8 deficiency on SAPinduced liver injury.Cilengitide,a specificαvβ3/5 integrin inhibitor,was used to investigate the possible mechanism of MFG-E8.RESULTS The results showed that MFG-E8 deficiency aggravated SAP-induced liver injury in mice,enhanced autophagy flux in hepatocyte,and worsened the degree of ferroptosis.Exogenous MFG-E8 reduced SAP-induced liver injury in a dose-dependent manner.Mechanistically,MFG-E8 mitigated excessive autophagy and inhibited ferroptosis in liver cells.Cilengitide abolished MFG-E8’s beneficial effects in SAP-induced liver injury.CONCLUSION MFG-E8 acts as an endogenous protective mediator in SAP-induced liver injury.MFG-E8 alleviates the excessive autophagy and inhibits ferroptosis in hepatocytes by binding to integrinαVβ3/5.

Integrins as attractive targets for cancer therapeutics

Integrins are transmembrane receptors that have been implicated in the biology of various human physiological and pathological processes.These molecules facilitate cell-extracellular matrix and cell-cell interactions,and they have been implicated in fibrosis,inflammation,thrombosis,and tumor metastasis.The role of integrins in tumor progression makes them promising targets for cancer treatment,and certain integrin antagonists,such as antibodies and synthetic peptides,have been effectively utilized in the clinic for cancer therapy.Here,we discuss the evidence and knowledge on the contribution of integrins to cancer biology.Furthermore,we summarize the clinical attempts targeting this family in anti-cancer therapy development.

Integrins and focal adhesion kinase in the malignant behavior of gliomas

Glioblastoma multiforme(GBM)is the most common type of glioma and is associated with a very poor prognosis.The standard treatment includes radiotherapy concurrent with temozolomide,however recently the Food and Drug Administration approved bevacizumab for use in patients with progressive glioblastoma following prior therapy.The limited number of treatment options points to the need for novel effective therapeutic approaches.A promising approach is the use of tyrosine kinase inhibitors(TKIs)in GBM treatment.However,the results from the majority of clinical trials using TKIs are not very encouraging.One growing area is the development of tumor-homing peptides that resemble the integrin recognition sequence RGD.In this article,the role of integrins and focal adhesion kinase in malignant glioma is reviewed,and an experimental study is proposed that will apply a strategy for peptide-mediated delivery of compounds deep into tumor parenchyma using tumor-homing peptides.

Reorganization of cytoskeletal proteins of mouse oocytes mediated by integrins

To study whether integrins on cell membrane ligate with intracellular cytoskeletal proteins and mediate their reorganization in egg activation, female mice were used for su- perovulation. The zona-free oocytes were incubated separately with specific ligand of integrins, an active RGD peptide, in vitro for certain period of time. RGE peptide and mouse capacitated sperm were used as controls. Freshly ovulated oocytes and those treated with different factors were immunostained with FITC-labeled anti-actin antibody, then detected with confocal micro- scope. The results demonstrated that freshly ovulated mouse oocytes, oocytes incubated for 2 h in vitro and those treated with control RGE peptide for 15 min showed hardly visible fluorescene or only thin fluorescence in plasma membrane region. Oocytes coincubated with sperms for 15 min and those treated with active RGD peptide for 10 min, 30 min and 2 hours respectively had strong and thick fluorescence in the plasma membrane and cortical region of oocytes, and some of them showed asymmetrically fluorescent distribution. It is proved that integrins on membrane are ligated directly with cytoskeletal protein. Integrins binding with their ligands regulate reor- ganization of cytoskelal protein, which may be involved in transmembrane signaling in egg acti- vation.

The importance of laminin at the blood-brain barrier

The blood-brain barrier is a unique property of central nervous system blood vessels that protects sensitive central nervous system cells from potentially harmful blood components.The mechanistic basis of this barrier is found at multiple levels,including the adherens and tight junction proteins that tightly bind adjacent endothelial cells and the influence of neighboring pericytes,microglia,and astrocyte endfeet.In addition,extracellular matrix components of the vascular basement membrane play a critical role in establishing and maintaining blood-brain barrier integrity,not only by providing an adhesive substrate for blood-brain barrier cells to adhere to,but also by providing guidance cues that strongly influence vascular cell behavior.The extracellular matrix protein laminin is one of the most abundant components of the basement membrane,and several lines of evidence suggest that it plays a key role in directing blood-brain barrier behavior.In this review,we describe the basic structure of laminin and its receptors,the expression patterns of these molecules in central nervous system blood vessels and how they are altered in disease states,and most importantly,how genetic deletion of different laminin isoforms or their receptors reveals the contribution of these molecules to blood-brain barrier function and integrity.Finally,we discuss some of the important unanswered questions in the field and provide a“to-do”list of some of the critical outstanding experiments.

miR-143-3p通过靶向integrinβ1抑制肝癌进展

目的探讨肝癌中miR-143-3p的表达及其对肝癌细胞恶性生物学行为的影响,并分析潜在的机制。方法收集肝癌组织,用RT-qPCR和Western blot法分别检测miR-143-3p和integrinβ1的表达。体外培养肝癌细胞,并用miR-143-3p mimics转染后,用XTT和EDU法检测过表达miR-143-3p对细胞增殖活力的影响,用Transwell法检测过表达miR-143-3p对细胞迁移与侵袭的影响,Western blot法检测过表达miR-143-3p对integrinβ1表达的影响。用荧光素酶活性法检测miR-143-3p与integrinβ1的靶向关系。用XTT、EdU和Transwell法检测过表达integrinβ1对已转染miR-143-3p mimics的肝癌细胞增殖、迁移与侵袭的影响。结果与癌旁正常组织比较,肝癌组织中miR-143-3p表达降低,integrinβ1表达升高,且二者均随疾病分期进展进一步降低或增高。过表达miR-143-3p能抑制肝癌细胞增殖、迁移和侵袭,并能下调integrinβ1表达。过表达integrinβ1能逆转miR-143-3p对肝癌细胞的抑制作用。integrinβ1为miR-143-3p的靶点。结论miR-143-3p在肝癌中表达下调,而上调miR-143-3p能通过靶向integrinβ1抑制肝癌细胞增殖、迁移与侵袭。

Integrin binding peptides facilitate growth and interconnected vascular-like network formation of rat primary cortical vascular endothelial cells in vitro

Neovascularization and angiogenesis in the brain are important physiological processes for normal brain development and repair/regeneration following insults. Integrins are cell surface adhesion receptors mediating important function of cells such as survival, growth and development during tissue organization, differentiation and organogenesis. In this study, we used an integrin-binding array platform to identify the important types of integrins and their binding peptides that facilitate adhesion, growth, development, and vascular-like network formation of rat primary brain microvascular endothelial cells. Brain microvascular endothelial cells were isolated from rat brain on post-natal day 7. Cells were cultured in a custom-designed integrin array system containing short synthetic peptides binding to 16 types of integrins commonly expressed on cells in vertebrates. After 7 days of culture, the brain microvascular endothelial cells were processed for immunostaining with markers for endothelial cells including von Willibrand factor and platelet endothelial cell adhesion molecule. 5-Bromo-2′-dexoyuridine was added to the culture at 48 hours prior to fixation to assess cell proliferation. Among 16 integrins tested, we found that α5β1, αvβ5 and αvβ8 greatly promoted proliferation of endothelial cells in culture. To investigate the effect of integrin-binding peptides in promoting neovascularization and angiogenesis, the binding peptides to the above three types of integrins were immobilized to our custom-designed hydrogel in three-dimensional(3 D) culture of brain microvascular endothelial cells with the addition of vascular endothelial growth factor. Following a 7-day 3 D culture, the culture was fixed and processed for double labeling of phalloidin with von Willibrand factor or platelet endothelial cell adhesion molecule and assessed under confocal microscopy. In the 3 D culture in hydrogels conjugated with the integrin-binding peptide, brain microvascular endothelial cells formed interconnected vascular-like network with clearly discernable lumens, which is reminiscent of brain microvascular network in vivo. With the novel integrin-binding array system, we identified the specific types of integrins on brain microvascular endothelial cells that mediate cell adhesion and growth followed by functionalizing a 3 D hydrogel culture system using the binding peptides that specifically bind to the identified integrins, leading to robust growth and lumenized microvascular-like network formation of brain microvascular endothelial cells in 3 D culture. This technology can be used for in vitro and in vivo vascularization of transplants or brain lesions to promote brain tissue regeneration following neurological insults.

Exosomes promote the invasion and metastasis of hepatocellular carcinoma cells via an integrin-dependent manner in the spleen-deficient state

Background:To investigate the detailed mechanism underlying the pro-metastatic effect of spleen deficiency(SD)syndrome on hepatocellular carcinoma(HCC).Methods:In the present study,our model was established based on an HCC mouse model induced by diethylnitrosamine using reserpine to induce SD.Exosomes were isolated and purified from mouse plasma samples using an exosome isolation kit.Subsequently,we verified the pro-metastatic effects of exosomes from the HCC mice with SD on HCC cells by transwell assays,wound healing assays,phalloidin staining in vitro,and lung metastasis assay of mice in vivo.Finally,we further explored the detailed mechanism underlying the pro-metastatic effect of exosomes from the HCC mice with SD on HCC cells.Results:We found that SD promoted the malignant progression of HCC in mice.Exosomes from HCC mice with SD enhanced the invasion and metastasis of HCC cells in vitro and in vivo.Mechanistically,upregulation of integrinα1,integrinβ1,and integrinβ5 seemed to play a key role in mediating the pro-metastatic effect of exosomes isolated from the HCC mice with SD,which was largely abrogated upon co-treatment with a broad-spectrum integrin inhibitor.Conclusion:Our findings demonstrated that exosomes promote the invasion and metastasis of HCC cells via an integrin-dependent manner in the spleen-deficient state that would contribute to our better understanding of the role of SD in HCC progression in traditional Chinese medicine,and thus management of the disease.

基于毒力因子FimH探讨尿感方抗尿道致病性大肠杆菌的作用机制

目的观察尿感方对尿道致病性大肠杆菌(UPEC)毒力因子FimH的作用和UPEC侵袭力的影响,并探讨其作用机制。方法UPEC分别经含空白尿液、尿感方含药尿液的培养基和空白培养基预处理后,观察UPEC毒力因子FimH表达的情况,并通过UPEC感染细胞模型,评价其侵袭力,同时采用Western blot、ELISA、RT-qPCR法检测整合素α3(integrinα3)、integrinβ1、p-FAK、p-Src、p-PI3K、p-αPAK蛋白表达,Rc1、Cdc42活性和三磷酸肌醇(IP3)水平,integrinα3、integrinβ1和细胞骨架蛋白[纽蛋白(vinculin)、踝蛋白(talin)、桩蛋白(paxillin)、F-肌动蛋白(F-actin)、α-辅助肌动蛋白(α-actinin)]mRNA表达。结果大鼠空白尿液和健康人空白尿液对UPEC FimH mRNA表达和UPEC入侵率无明显影响(P>0.05),对integrinα3、integrinβ1 mRNA和蛋白表达,p-FAK、p-Src、p-PI3K、p-αPAK蛋白表达,Rc1、Cdc42活性,IP3水平,细胞骨架蛋白mRNA表达均无明显影响(P>0.05)。大鼠含药尿液和健康人含药尿液降低了FimH mRNA表达,UPEC入侵率,integrinα3、integrinβ1 mRNA和蛋白表达,p-FAK、p-Src、p-PI3K、p-αPAK蛋白表达,Rc1、Cdc42活性,IP3水平,细胞骨架蛋白mRNA表达(P<0.05,P<0.01)。结论尿感方能影响UPEC FimH表达,减弱UPEC侵袭力,其作用机制与FimH/integrinα3、β1/FAK信号传导通路有关。