Integrin α6β4 requires plectin and vimentin for adhesion complex distribution and invasive growth

Mutual adhesion of Lactobacillus spp. to intestinal cells: A review of perspectives on surface layer proteins and cell surface receptors

The bacterial ability to adhere and colonize in the gut is a key prerequisite to become a probiotic. Lactobacillus spp. surface layer proteins (SLPs) play an important role for such functions in the human body. Interestingly, all SLPs in spite of their structural variation promote adhesion and colonization. A clear understanding about the binding sites of SLPs with the host and their binding modes would help to precisely reveal the process of Lactobacillus spp.-host interaction. Therefore, in this paper, we have sorted out the Lactobacillus spp. SLPs and their adhesion sites in human intestinal cells. Such SLPs included surface layer protein, motif proteins, binding proteins and moonlighting proteins, while enterocyte adhesion receptors included transmembrane glycoproteins and extracellular matrix proteins. We also summarized the tools to assess the adhesion by Lactobacillus spp. Finally, we recommended that three-dimensional cell models and intestinal microarrays could be major tools for assessing adhesion in the future.

Integrin α6β4 Upregulates PTPRZ1 Through UCHL1-Mediated Hif-1α Nuclear Accumulation to Promote Triple-Negative Breast Cancer Cell Invasive Properties

Integrin α6β4 drives triple-negative breast cancer (TNBC) aggressiveness through the transcriptional regulation of key genes. Here, we investigated how integrin α6β4 regulates protein tyrosine phosphatase receptor type Z1 (PTPRZ1). Using stable re-expression of integrin β4 (ITGB4) in cells naturally devoid of integrin α6β4 or knockdown or knockout (KO) of ITGB4, we found that integrin α6β4 regulates PTPRZ1 expression. To gain mechanistic insight, we focused on Hif-1α due to the impact of integrin α6β4 on a hypoxia-associated signature. We found that nuclear localization of Hif-1α, but not Hif-2α, was substantially enhanced with integrin α6β4 signaling. Hif-1α knockdown by shRNA or chemical inhibition decreased PTPRZ1 expression, while chemical activation of Hif-1α increased it. Upstream of Hif-1α, integrin α6β4 upregulates UCHL1 to stabilize Hif-1α and ultimately regulate PTPRZ1. Inhibition of UCHL1 and PTPRZ1 dramatically decreases integrin α6β4-mediated cell migration and three-dimensional invasive growth. Finally, public breast cancer database analyses demonstrated that ITGB4 correlates with PTPRZ1 and that high expression of ITGB4, UCHL1, HIF1A, and PTPRZ1 associated with decreased overall survival, distant metastasis free survival, post progression survival, and relapse-free survival. In summary, these findings provide a novel function of integrin α6β4 in promoting tumor invasive phenotypes through UCHL1-Hif-1α-mediated regulation of PTPRZ1.

The mechanism of ITGB4 in tumor migration and invasion

Integrin β4 (ITGB4) is a transmembrane protein that functions as a mechanosensor, mediating the bidirectional exchange of information between the intracellular and extracellular matrices. ITGB4 plays a critical role in cell adhesion, migration, and signaling. Numerous studies have implicated ITGB4 as a key facilitator of tumor migration and invasion. This review provides a foundational description of the mechanisms by which ITGB4 regulates tumor migration and invasion through pathways involving focal adhesion kinase (FAK), protein kinase B (AKT), and matrix metalloproteinases (MMPs). These mechanisms encompass epithelial-mesenchymal transition (EMT), phosphorylation, and methylation of associated molecules. Additionally, this review explores the role of ITGB4 in the migration and invasion of prevalent clinical tumors, including those of the digestive system, breast, and prostate.

How cytoskeletal crosstalk makes cells move: Bridging cell-free and cell studies

Cell migration is a fundamental process for life and is highly dependent on the dynamical and mechanical properties of the cytoskeleton. Intensive physical and biochemical crosstalk among actin, microtubules, and intermediate filaments ensures their coordination to facilitate and enable migration. In this review, we discuss the different mechanical aspects that govern cell migration and provide, for each mechanical aspect, a novel perspective by juxtaposing two complementary approaches to the biophysical study of cytoskeletal crosstalk: live-cell studies (often referred to as top-down studies) and cell-free studies (often referred to as bottom-up studies). We summarize the main findings from both experimental approaches, and we provide our perspective on bridging the two perspectives to address the open questions of how cytoskeletal crosstalk governs cell migration and makes cells move.

Vimentin at the core of wound healing

As a member of the large family of intermediate filaments (IFs), vimentin has emerged as a highly dynamic and versatile cytoskeletal protein involved in many key processes of wound healing. It is well established that vimentin is involved in epithelial-mesenchymal transition (EMT) during wound healing and metastasis, during which epithelial cells acquire more dynamic and motile characteristics. Moreover, vimentin participates in multiple cellular activities supporting growth, proliferation, migration, cell survival, and stress resilience. Here, we explore the role of vimentin at each phase of wound healing, with focus on how it integrates different signaling pathways and protects cells in the fluctuating and challenging environments that characterize a healing tissue.

Recent progress on the effect of extracellular matrix on occurrence and progression of breast cancer

Breast cancer (BC) metastasis is an enormous challenge targeting BC therapy. The extracellular matrix (ECM), the principal component of the BC metastasis niche, is the pivotal driver of breast tumor development, whose biochemical and biophysical characteristics have attracted widespread attention. Here, we review the biological effects of ECM constituents and the influence of ECM stiffness on BC metastasis and drug resistance. We provide an overview of the relative signal transduction mechanisms, existing metastasis models, and targeted drug strategies centered around ECM stiffness. It will shed light on exploring more underlying targets and developing specific drugs aimed at ECM utilizing biomimetic platforms, which are promising for breast cancer treatment.

Integrin α6β4 signals through DNA damage response pathway to sensitize breast cancer cells to cisplatin

Integrin α6β4 is highly expressed in triple negative breast cancer (TNBC) and drives its most aggressive traits; however, its impact on chemotherapeutic efficacy remains untested. We found that integrin α6β4 signaling promoted sensitivity to cisplatin and carboplatin but not to other chemotherapies tested. Mechanistic investigations revealed that integrin α6β4 stimulated the activation of ATM, p53, and 53BP1, which required the integrin β4 signaling domain. Genetic manipulation of gene expression demonstrated that mutant p53 cooperated with integrin α6β4 for cisplatin sensitivity and was necessary for downstream phosphorylation of 53BP1 and enhanced ATM activation. Additionally, we found that in response to cisplatin-induced DNA double strand break (DSB), integrin α6β4 suppressed the homologous recombination (HR) activity and enhanced non-homologous end joining (NHEJ) repair activity. Finally, we discovered that integrin α6β4 preferentially activated DNA-PK, facilitated DNA-PK-p53 and p53-53BP1 complex formation in response to cisplatin and required DNA-PK to enhance ATM, 53BP1 and p53 activation as well as cisplatin sensitivity. In summary, we discovered a novel function of integrin α6β4 in promoting cisplatin sensitivity in TNBC through DNA damage response pathway.

Ancient Origins of Cytoskeletal Crosstalk: Spectraplakin-like Proteins Precede the Emergence of Cortical Microtubule Stabilization Complexes as Crosslinkers

Adhesion between cells and the extracellular matrix (ECM) is one of the prerequisites for multicellularity, motility, and tissue specialization. Focal adhesions (FAs) are defined as protein complexes that mediate signals from the ECM to major components of the cytoskeleton (microtubules, actin, and intermediate filaments), and their mutual communication determines a variety of cellular processes. In this study, human cytoskeletal crosstalk proteins were identified by comparing datasets with experimentally determined cytoskeletal proteins. The spectraplakin dystonin was the only protein found in all datasets. Other proteins (FAK, RAC1, septin 9, MISP, and ezrin) were detected at the intersections of FAs, microtubules, and actin cytoskeleton. Homology searches for human crosstalk proteins as queries were performed against a predefined dataset of proteomes. This analysis highlighted the importance of FA communication with the actin and microtubule cytoskeleton, as these crosstalk proteins exhibit the highest degree of evolutionary conservation. Finally, phylogenetic analyses elucidated the early evolutionary history of spectraplakins and cortical microtubule stabilization complexes (CMSCs) as model representatives of the human cytoskeletal crosstalk. While spectraplakins probably arose at the onset of opisthokont evolution, the crosstalk between FAs and microtubules is associated with the emergence of metazoans. The multiprotein complexes contributing to cytoskeletal crosstalk in animals gradually gained in complexity from the onset of metazoan evolution.

First person – Lei Qi

First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Lei Qi is first author on ‘ Integrin α6β4 requires plectin and vimentin for adhesion complex distribution and invasive growth’, published in JCS. Lei is a research scientist in the lab of Kathleen L. O'Connor at University of Kentucky, Lexington, USA, investigating cellular mechanotransduction and epigenetics.