Tetraspanin CD151 and integrin α3β1 contribute to the stabilization of integrin α6β4-containing cell-matrix adhesions

Impact of CD151 overexpression on prognosis and therapy in non-small cell lung cancer patients lacking EGFR mutations

This study investigates CD151, a protein linked to cancer progression, in non-small cell lung cancer (NSCLC) patients without epidermal growth factor receptor (EGFR) mutations. These patients often have limited treatment options. The study used retrospective analysis to examine 157 adenocarcinoma biopsy specimens and 199 patient cases from The Cancer Genome Atlas, correlating CD151 expression with patient survival. Cellular studies revealed that CD151 interacts with EGFR, influencing epidermal growth factor (EGF)-induced cell proliferation and the effectiveness of the EGFR inhibitor, erlotinib. A strong association was found between CD151 expression and EGFR mutation status. High CD151 expression in the absence of EGFR mutations is correlated with poorer survival outcomes. Biological assays showed that CD151 colocalizes and associates with EGFR, playing a crucial role in regulating EGF-induced cell proliferation via the AKT and ERK1/2 pathways. Importantly, CD151 expression was found to influence the anti-proliferative effects of the EGFR tyrosine kinase inhibitor, erlotinib. High CD151 expression, in the absence of EGFR mutations, was associated with poorer survival outcomes. It could serve as a potential prognostic marker and influence cellular responses to EGFR-targeted treatments. This study highlights CD151 as a potential novel target for therapeutic intervention in NSCLC, especially in populations lacking EGFR mutations.

Mechanism underlying the role of integrin α3β1 in adhesive dysfunction between thyroid cells induced by diesel engine exhaust particles

The role and mechanisms of DEP exposure on thyroid injury are not yet clear. This study explores thyroid damage induced by in vivo DEP exposure using a mouse model. This study has observed alterations in thyroid follicular architecture, including rupture, colloid overflow, and the formation of voids. Additionally, there was a significant decrease in the expression levels of proteins involved in thyroid hormone synthesis, such as thyroid peroxidase and thyroglobulin, their trend of change is consistent with the damage to the thyroid structure. Serum levels of triiodothyronine and tetraiodothyronine were raise. However, the decrease in TSH expression suggests that the function of the HPT axis is unaffected. To delve deeper into the intrinsic mechanisms of thyroid injury, we performed KEGG pathway enrichment analysis, which revealed notable alterations in the cell adhesion signaling pathway. Our immunofluorescence results show that DEP exposure impairs thyroid adhesion, and integrin α3β1 plays an important role. CD151 binds to α3β1, promoting multimolecular complex formation and activating adhesion-dependent small GTPases. Our in vitro model has confirmed the pivotal role of integrin α3β1 in thyroid cell adhesion, which may be mediated by the CD151/α3β1/Rac1 pathway. In summary, exposure to DEP disrupts the structure and function of the thyroid, a process that likely involves the regulation of cell adhesion through the CD151/α3β1/Rac1 pathway, leading to glandular damage.

Junctional epithelium and hemidesmosomes: Tape and rivets for solving the "percutaneous device dilemma" in dental and other permanent implants

The percutaneous device dilemma describes etiological factors, centered around the disrupted epithelial tissue surrounding non-remodelable devices, that contribute to rampant percutaneous device infection. Natural percutaneous organs, in particular their extracellular matrix mediating the "device"/epithelium interface, serve as exquisite examples to inspire longer lasting long-term percutaneous device design. For example, the tooth's imperviousness to infection is mediated by the epithelium directly surrounding it, the junctional epithelium (JE). The hallmark feature of JE is formation of hemidesmosomes, cell/matrix adhesive structures that attach surrounding oral gingiva to the tooth's enamel through a basement membrane. Here, the authors survey the multifaceted functions of the JE, emphasizing the role of the matrix, with a particular focus on hemidesmosomes and their five main components. The authors highlight the known (and unknown) effects dental implant - as a model percutaneous device - placement has on JE regeneration and synthesize this information for application to other percutaneous devices. The authors conclude with a summary of bioengineering strategies aimed at solving the percutaneous device dilemma and invigorating greater collaboration between clinicians, bioengineers, and matrix biologists.

Genetic susceptibility loci for Chlamydia trachomatis endometrial infection influence expression of genes involved in T cell function, tryptophan metabolism and epithelial integrity

Objectives

Identify genetic loci of enhanced susceptibility to Chlamydial trachomatis (Ct) upper genital tract infection in women.

Methods

We performed an integrated analysis of DNA genotypes and blood-derived mRNA profiles from 200 Ct-exposed women to identify expression quantitative trait loci (eQTL) and determine their association with endometrial chlamydial infection using a mediation test. We further evaluated the effect of a lead eQTL on the expression of CD151 by immune cells from women with genotypes associated with low and high whole blood expression of CD151, respectively.

Results

We identified cis-eQTLs modulating mRNA expression of 81 genes (eGenes) associated with altered risk of ascending infection. In women with endometrial infection, eGenes involved in proinflammatory signaling were upregulated. Downregulated eGenes included genes involved in T cell functions pivotal for chlamydial control. eGenes encoding molecules linked to metabolism of tryptophan, an essential chlamydial nutrient, and formation of epithelial tight junctions were also downregulated in women with endometrial infection. A lead eSNP rs10902226 was identified regulating CD151, a tetrospanin molecule important for immune cell adhesion and migration and T cell proliferation. Further in vitro experiments showed that women with a CC genotype at rs10902226 had reduced rates of endometrial infection with increased CD151 expression in whole blood and T cells when compared to women with a GG genotype.

Conclusions

We discovered genetic variants associated with altered risk for Ct ascension. A lead eSNP for CD151 is a candidate genetic marker for enhanced CD4 T cell function and reduced susceptibility.

Integrin α3/α6 and αV are implicated in ADAM15-activated FAK and EGFR signalling pathway individually and promote non-small-cell lung cancer progression

Disintegrin-metalloproteinase 15(ADAM15), a member of disintegrin metalloproteinases (ADAMs), plays important roles in various cancer types. However, the underlying ADAM15 functioning in lung cancer is still unclear. In the present study, we find that ADAM15 regulates the epidermal growth factor receptor/focal adhesion kinase (EGFR/FAK) signalling pathway by interactions with integrins. Integrin αV is involved in ADAM15-mediated FAK signalling. Further, we find that ADAM15 and CD151 were co-expressed, and the presence of ADAM15 affected the integrin α3/α6-related EGFR signalling pathway by cooperating with CD151. In addition, we also prove the effect of ADAM15 on proliferation in nude mice. Finally, we show that ADAM15 is a direct target of miR-204-5p by luciferase reporter assays, qRT-PCR and western blot analyses. Our findings provide molecular and cellular evidence that ADAM15 promotes cell proliferation and metastasis in NSCLC, which might provide a potential target for NSCLC treatment.

Crystal structure of the Tspan15 LEL domain reveals a conserved ADAM10 binding site

Tetraspanins are four-pass transmembrane proteins that function by regulating trafficking of partner proteins and organizing signaling complexes in the membrane. Tspan15, one of a six-member TspanC8 subfamily, forms a complex that regulates the trafficking, maturation, and substrate selectivity of the transmembrane protease ADAM10, an essential enzyme in mammalian physiology that cleaves a wide variety of membrane-anchored substrates, including Notch receptors, amyloid precursor protein, cadherins, and growth factors. We present here crystal structures of the Tspan15 large extracellular loop (LEL) required for functional association with ADAM10 both in isolation and in complex with the Fab fragment of an anti-Tspan15 antibody. Comparison of the Tspan15 LEL with other tetraspanin LEL structures shows that a core helical framework buttresses a variable region that structurally diverges among LELs. Using co-immunoprecipitation and a cellular N-cadherin cleavage assay, we identify a site on Tspan15 required for both ADAM10 binding and promoting substrate cleavage.

JAM-A interacts with α3β1 integrin and tetraspanins CD151 and CD9 to regulate collective cell migration of polarized epithelial cells

Junctional adhesion molecule (JAM)-A is a cell adhesion receptor localized at epithelial cell–cell contacts with enrichment at the tight junctions. Its role during cell–cell contact formation and epithelial barrier formation has intensively been studied. In contrast, its role during collective cell migration is largely unexplored. Here, we show that JAM-A regulates collective cell migration of polarized epithelial cells. Depletion of JAM-A in MDCK cells enhances the motility of singly migrating cells but reduces cell motility of cells embedded in a collective by impairing the dynamics of cryptic lamellipodia formation. This activity of JAM-A is observed in cells grown on laminin and collagen-I but not on fibronectin or vitronectin. Accordingly, we find that JAM-A exists in a complex with the laminin- and collagen-I-binding α3β1 integrin. We also find that JAM-A interacts with tetraspanins CD151 and CD9, which both interact with α3β1 integrin and regulate α3β1 integrin activity in different contexts. Mapping experiments indicate that JAM-A associates with α3β1 integrin and tetraspanins CD151 and CD9 through its extracellular domain. Similar to depletion of JAM-A, depletion of either α3β1 integrin or tetraspanins CD151 and CD9 in MDCK cells slows down collective cell migration. Our findings suggest that JAM-A exists with α3β1 integrin and tetraspanins CD151 and CD9 in a functional complex to regulate collective cell migration of polarized epithelial cells.

The Tongue Squamous Carcinoma Cell Line Cal27 Primarily Employs Integrin α6β4-Containing Type II Hemidesmosomes for Adhesion Which Contribute to Anticancer Drug Sensitivity

Integrins are heterodimeric cell surface glycoproteins used by cells to bind to the extracellular matrix (ECM) and regulate tumor cell proliferation, migration and survival. A causative relationship between integrin expression and resistance to anticancer drugs has been demonstrated in different tumors, including head and neck squamous cell carcinoma. Using a Cal27 tongue squamous cell carcinoma model, we have previously demonstrated that de novo expression of integrin αVβ3 confers resistance to several anticancer drugs (cisplatin, mitomycin C and doxorubicin) through a mechanism involving downregulation of active Src, increased cell migration and invasion. In the integrin αVβ3 expressing Cal27-derived cell clone 2B1, αVβ5 expression was also increased, but unrelated to drug resistance. To identify the integrin adhesion complex (IAC) components that contribute to the changes in Cal27 and 2B1 cell adhesion and anticancer drug resistance, we isolated IACs from both cell lines. Mass spectrometry (MS)-based proteomics analysis indicated that both cell lines preferentially, but not exclusively, use integrin α6β4, which is classically found in hemidesmosomes. The anticancer drug resistant cell clone 2B1 demonstrated an increased level of α6β4 accompanied with increased deposition of a laminin-332-containing ECM. Immunofluorescence and electron microscopy demonstrated the formation of type II hemidesmosomes by both cell types. Furthermore, suppression of α6β4 expression in both lines conferred resistance to anticancer drugs through a mechanism independent of αVβ3, which implies that the cell clone 2B1 would have been even more resistant had the upregulation of α6β4 not occurred. Taken together, our results identify a key role for α6β4-containing type II hemidesmosomes in regulating anticancer drug sensitivity.

Regulation of hemidesmosome dynamics and cell signaling by integrin α6β4

Hemidesmosomes (HDs) are specialized multiprotein complexes that connect the keratin cytoskeleton of epithelial cells to the extracellular matrix (ECM). In the skin, these complexes provide stable adhesion of basal keratinocytes to the underlying basement membrane. Integrin α6β4 is a receptor for laminins and plays a vital role in mediating cell adhesion by initiating the assembly of HDs. In addition, α6β4 has been implicated in signal transduction events that regulate diverse cellular processes, including proliferation and survival. In this Review, we detail the role of α6β4 in HD assembly and beyond, and we discuss the molecular mechanisms that regulate its function.

CD151 drives cancer progression depending on integrin α3β1 through EGFR signaling in non-small cell lung cancer

Background

Tetraspanins CD151, a transmembrane 4 superfamily protein, has been identified participating in the initiation of a variety of cancers. However, the precise function of CD151 in non-small cell lung cancer (NSCLC) remains unclear. Here, we addressed the pro-tumoral role of CD151 in NSCLC by targeting EGFR/ErbB2 which favors tumor proliferation, migration and invasion.

Methods

First, the mRNA expression levels of CD151 in NSCLC tissues and cell lines were measured by RT-PCR. Meanwhile, CD151 and its associated proteins were analyzed by western blotting. The expression levels of CD151 in NSCLC samples and its paired adjacent lung tissues were then verified by Immunohistochemistry. The protein interactions are evaluated by co-immunoprecipitation. Flow cytometry was applied to cell cycle analysis. CCK-8, EdU Incorporation, and clonogenic assays were used to analyze cell viability. Wound healing, transwell migration, and matrigel invasion assays were utilized to assess the motility of tumor cells. To investigate the role of CD151 in vivo, lung carcinoma xenograft mouse model was applied.

Results

High CD151 expression was identified in NSCLC tissues and cell lines, and its high expression was significantly associated with poor prognosis of NSCLC patients. Further, knockdown of CD151 in vitro inhibited tumor proliferation, migration, and invasion. Besides, inoculation of nude mice with CD151-overexpressing tumor cells exhibited substantial tumor proliferation compared to that in control mice which inoculated with vector-transfected tumor cells. Noteworthy, we found that overexpression of CD151 conferred cell migration and invasion by interacting with integrins. We next sought to demonstrate that CD151 regulated downstream signaling pathways via activation of EGFR/ErbB2 in NSCLC cells. Therefore, we infer that CD151 probably affects the sensitivity of NSCLC in response to anti-cancer drugs.

Conclusions

Based on these results, we demonstrated a new mechanism of CD151-mediated tumor progression by targeting EGFR/ErbB2 signaling pathway, by which CD151 promotes NSCLC proliferation, migration, and invasion, which may considered as a potential target of NSCLC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01998-4.

EGFR-dependent tyrosine phosphorylation of integrin β4 is not required for downstream signaling events in cancer cell lines

In epithelial cancers, the epidermal growth factor receptor (EGFR) and integrin α6β4 are frequently overexpressed and found to synergistically activate intracellular signaling pathways that promote cell proliferation and migration. In cancer cells, the β4 subunit is phosphorylated at tyrosine residues not normally recognized as kinase substrates; however, the function of these phosphotyrosine residues in cancer cells is a subject of much debate. In EGFR-overexpressing carcinoma cells, we found that the Src family kinase (SFK) inhibitor PP2 reduces β4 tyrosine phosphorylation following the activation of EGFR. However, siRNA mediated knockdown of the SFKs Src, Fyn, Yes and Lyn, individually or in combination, did not affect the EGF-induced phosphorylation of β4. Using phospho-peptide affinity chromatography and mass spectrometry, we found that PLCγ1 binds β4 at the phosphorylated residues Y1422/Y1440, but were unable to verify this interaction in A431 carcinoma cells that overexpress the EGFR. Furthermore, using A431 cells devoid of β4 or reconstituted with phenylalanine specific mutants of β4, the activation of several downstream signaling pathways, including PLCγ/PKC, MAPK and PI3K/Akt, were not substantially affected. We conclude that tyrosine-phosphorylated β4 does not enhance EGFR-mediated signaling in EGFR-overexpressing cells, despite the fact that this integrin subunit is highly tyrosine phosphorylated in these cells.

Key Role of CD151-integrin Complex in Lung Cancer Metastasis and Mechanisms Involved

Tetraspanin CD151 was found to be upregulated in malignant cell types and has been identified as a tumor metastasis promoter. In this study, we aimed to examine the role of the CD151-integrin complex in lung cancer metastasis and the underlying mechanisms. CD151 QRD^194-196 →AAA^194-196 mutant was generated and used to transfect A549 human lung adenocarcinoma cells. We found that there was no significant difference in CD151 protein expression between CD151 and CD151-AAA mutant groups. In vitro, CD151-AAA mutant delivery abrogated the migration and invasion of A549 cells, which was promoted by CD151 gene transfer. Furthermore, CD151-AAA delivery failed to activate FAK and p130Cas signaling pathways. Western blot and immunohistochemical staining showed strong CD151 expression in lung cancerous tissues but not in adjacent normal tissues. Increased level of CD151 protein was observed in 20 of the patients and the positive rate of CD151 protein in specimens was 62.5% (20/32). In addition, CD151 was co-localized with α3 integrin at the cell-cell contact site in carcinoma tissues. These results suggested that the disruption of the CD151-α3 integrin complex may impair the metastasis-promoting effects and signaling events induced by CD151 in lung cancer. Our findings identified a key role for CD151-α3 integrin complex as a promoter in the lung cancer.

Expression of Integrin β6 and HAX-1 Correlates with Aggressive Features and Poor Prognosis in Esophageal Squamous Cell Carcinoma

Purpose

The development of esophageal squamous cell carcinoma (ESCC) is a complicated process in which cell adhesion and motility, mediated by integrins, are involved through connecting the cytoskeleton to extracellular matrix. Different mechanisms via which integrin β6 participates in cancer invasion and metastasis have been described by numerous studies; however, the expression and clinical significance of integrin β6 in ESCC remain unknown.

Methods

To investigate the differential expression of integrin β6 in ESCC, qPCR and immunohistochemistry assays were performed in 10 paired human samples. A total of 137 ESCC samples were further enrolled to evaluate the expression levels of integrin β6 and its endocytic trafficking regulator HS1-associated protein X-1 (HAX-1), followed by the evaluation of their correlation with clinicopathological parameters. The overall survival was analyzed using the Kaplan–Meier method, with significant variables further evaluated by multivariate Cox regression analyses.

Results

The expression of integrin β6 was markedly increased in ESCC compared with matched adjacent normal tissues. Among the ESCC samples, positive expression of integrin β6 was observed in 41.6% tumors, which was associated with histological differentiation, lymph node metastasis and TNM stage. High expression of HAX-1 was detected in 47.4% tumors, and there was a positive relationship between the expression levels of integrin β6 and HAX-1. Furthermore, the expression of integrin β6 and HAX-1 were independent unfavorable indicators for prognosis. Patients with positive integrin β6 and high HAX-1 expression demonstrated worst outcomes.

Conclusion

The present findings suggested the predictive value of integrin β6 and HAX-1 as independent indicators of poor prognosis for patients with ESCC, both of which may contribute to the tumor proliferation and metastasis, leading to ESCC progression. Therefore, combined targeting of integrin β6 and HAX-1 may provide a potential novel approach for the treatment of ESCC.

Crosstalk between Cell Adhesion Complexes in Regulation of Mechanotransduction

Physical forces regulate numerous biological processes during development, physiology, and pathology. Forces between the external environment and intracellular actin cytoskeleton are primarily transmitted through integrin-containing focal adhesions and cadherin-containing adherens junctions. Crosstalk between these complexes is well established and modulates the mechanical landscape of the cell. However, integrins and cadherins constitute large families of adhesion receptors and form multiple complexes by interacting with different ligands, adaptor proteins, and cytoskeletal filaments. Recent findings indicate that integrin-containing hemidesmosomes oppose force transduction and traction force generation by focal adhesions. The cytolinker plectin mediates this crosstalk by coupling intermediate filaments to the actin cytoskeleton. Similarly, cadherins in desmosomes might modulate force generation by adherens junctions. Moreover, mechanotransduction can be influenced by podosomes, clathrin lattices, and tetraspanin-enriched microdomains. This review discusses mechanotransduction by multiple integrin- and cadherin-based cell adhesion complexes, which together with the associated cytoskeleton form an integrated network that allows cells to sense, process, and respond to their physical environment.

Comparative interactomics analysis reveals potential regulators of α6β4 distribution in keratinocytes

The integrin α6β4 and cytoskeletal adaptor plectin are essential components of type I and type II hemidesmosomes (HDs). We recently identified an alternative type II HD adhesion complex that also contains CD151 and the integrin α3β1. Here, we have taken a BioID proximity labeling approach to define the proximity protein environment for α6β4 in keratinocytes. We identified 37 proteins that interacted with both α6 and β4, while 20 and 78 proteins specifically interacted with the α6 and β4 subunits, respectively. Many of the proximity interactors of α6β4 are components of focal adhesions (FAs) and the cortical microtubule stabilizing complex (CMSC). Though the close association of CMSCs with α6β4 in HDs was confirmed by immunofluorescence analysis, CMSCs have no role in the assembly of HDs. Analysis of the β4 interactome in the presence or absence of CD151 revealed that they are strikingly similar; only 11 different interactors were identified. One of these was the integrin α3β1, which interacted with α6β4 more strongly in the presence of CD151 than in its absence. These findings indicate that CD151 does not significantly contribute to the interactome of α6β4, but suggest a role of CD151 in linking α3β1 and α6β4 together in tetraspanin adhesion structures.

Summary: Comparative interactomics analysis reveals close proximity of HDs, FAs and CMSCs, and a role of CD151 in linking α3β1 and α6β4 together in an alternative type II HD-like adhesion complex.

Skin proteomics - analysis of the extracellular matrix in health and disease

INTRODUCTION

The skin protects the human body from external insults and regulates water and temperature homeostasis. A highly developed extracellular matrix (ECM) supports the skin and instructs its cell functions. Reduced functionality of the ECM is often associated with skin diseases that cause physical impairment and also have implications on social interactions and quality of life of affected individuals.

AREAS COVERED

With a focus on the skin ECM we discuss how mass spectrometry (MS)-based proteomic approaches first contributed to establishing skin protein inventories and then facilitated elucidation of molecular functions and disease mechanisms.

EXPERT OPINION

MS-based proteomic approaches have significantly contributed to our understanding of skin pathophysiology, but also revealed the challenges in assessing the skin ECM. The numerous posttranslational modifications of ECM proteins, like glycosylation, crosslinking, oxidation, and proteolytic maturation in disease settings can be difficult to tackle and remain understudied. Increased ease of handling of LC-MS/MS systems and automated/streamlined data analysis pipelines together with the accompanying increased usage of LC-MS/MS approaches will ensure that in the coming years MS-based proteomic approaches will continue to play a vital part in skin disease research. They will facilitate the elucidation of molecular disease mechanisms and, ultimately, identification of new druggable targets.

Expression and distribution of CD151 as a partner of alpha6 integrin in male germ cells

The physiological importance of CD151 tetraspanin is known from somatic cells and its outside-in signalling through integrins was described. In male germ cells, two tetraspanins, CD9 and CD81, are involved in sperm-egg membrane fusion, and similarly to integrins, they occupy characteristic regions. We report here on a newly discovered presence of CD151 in sperm, and present its expression and distribution during spermatogenesis and sperm transition during the acrosome reaction. We traced CD151 gene and protein expression in testicular cell subpopulations, with strong enrichment in spermatogonia and spermatids. The testicular and epididymal localization pattern is designated to the sperm head primary fusion site called the equatorial segment and when compared to the acrosome vesicle status, CD151 was located into the inner acrosomal membrane overlying the nucleus. Moreover, we show CD151 interaction with α6 integrin subunit, which forms a dimer with β4 as a part of cis-protein interactions within sperm prior to gamete fusion. We used mammalian species with distinct sperm morphology and sperm maturation such as mouse and bull and compared the results with human. In conclusion, the delivered findings characterise CD151 as a novel sperm tetraspanin network member and provide knowledge on its physiology in male germ cells.

Hemidesmosomes modulate force generation via focal adhesions

Hemidesmosomes are specialized cell-matrix adhesion structures that are associated with the keratin cytoskeleton. Although the adhesion function of hemidesmosomes has been extensively studied, their role in mechanosignaling and transduction remains largely unexplored. Here, we show that keratinocytes lacking hemidesmosomal integrin α6β4 exhibit increased focal adhesion formation, cell spreading, and traction-force generation. Moreover, disruption of the interaction between α6β4 and intermediate filaments or laminin-332 results in similar phenotypical changes. We further demonstrate that integrin α6β4 regulates the activity of the mechanosensitive transcriptional regulator YAP through inhibition of Rho-ROCK-MLC- and FAK-PI3K-dependent signaling pathways. Additionally, increased tension caused by impaired hemidesmosome assembly leads to a redistribution of integrin αVβ5 from clathrin lattices to focal adhesions. Our results reveal a novel role for hemidesmosomes as regulators of cellular mechanical forces and establish the existence of a mechanical coupling between adhesion complexes.