An amphipathic helix of vinexin α is necessary for a substrate stiffness-dependent conformational change in vinculin

Genetic complexity of diagnostically unresolved Ehlers-Danlos syndrome

BACKGROUND

The Ehlers-Danlos syndromes (EDS) are heritable disorders of connective tissue (HDCT), reclassified in the 2017 nosology into 13 subtypes. The genetic basis for hypermobile Ehlers-Danlos syndrome (hEDS) remains unknown.

METHODS

Whole exome sequencing (WES) was undertaken on 174 EDS patients recruited from a national diagnostic service for complex EDS and a specialist clinic for hEDS. Patients had already undergone expert phenotyping, laboratory investigation and gene sequencing, but were without a genetic diagnosis. Filtered WES data were reviewed for genes underlying Mendelian disorders and loci reported in EDS linkage, transcriptome and genome-wide association studies (GWAS). A genetic burden analysis (Minor Allele Frequency (MAF) <0.05) incorporating 248 Avon Longitudinal Study of Parents and Children (ALSPAC) controls sequenced as part of the UK10K study was undertaken using TASER methodology.

RESULTS

Heterozygous pathogenic (P) or likely pathogenic (LP) variants were identified in known EDS and Loeys-Dietz (LDS) genes. Multiple variants of uncertain significance where segregation and functional analysis may enable reclassification were found in genes associated with EDS, LDS, heritable thoracic aortic disease (HTAD), Mendelian disorders with EDS symptomatology and syndromes with EDS-like features. Genetic burden analysis revealed a number of novel loci, although none reached the threshold for genome-wide significance. Variants with biological plausibility were found in genes and pathways not currently associated with EDS or HTAD.

CONCLUSIONS

We demonstrate the clinical utility of large panel-based sequencing and WES for patients with complex EDS in distinguishing rare EDS subtypes, LDS and related syndromes. Although many of the P and LP variants reported in this cohort would be identified with current panel testing, they were not at the time of this study, highlighting the use of extended panels and WES as a clinical tool for complex EDS. Our results are consistent with the complex genetic architecture of EDS and suggest a number of novel hEDS and HTAD candidate genes and pathways.

Mechanical tumor microenvironment and transduction: cytoskeleton mediates cancer cell invasion and metastasis

Metastasis is a complicated, multistep process that is responsible for over 90% of cancer-related death. Metastatic disease or the movement of cancer cells from one site to another requires dramatic remodeling of the cytoskeleton. The regulation of cancer cell migration is determined not only by biochemical factors in the microenvironment but also by the biomechanical contextual information provided by the extracellular matrix (ECM). The responses of the cytoskeleton to chemical signals are well characterized and understood. However, the mechanisms of response to mechanical signals in the form of externally applied force and forces generated by the ECM are still poorly understood. Furthermore, understanding the way cellular mechanosensors interact with the physical properties of the microenvironment and transmit the signals to activate the cytoskeletal movements may help identify an effective strategy for the treatment of cancer. Here, we will discuss the role of tumor microenvironment during cancer metastasis and how physical forces remodel the cytoskeleton through mechanosensing and transduction.

Mechanisms of Arterial Stiffening: From Mechanotransduction to Epigenetics

Arterial stiffness is a major independent risk factor for cardiovascular complications causing isolated systolic hypertension and increased pulse pressure in the microvasculature of target organs. Stiffening of the arterial wall is determined by common mechanisms including reduced elastin/collagen ratio, production of elastin cross-linking, reactive oxygen species-induced inflammation, calcification, vascular smooth muscle cell stiffness, and endothelial dysfunction. This brief review will discuss current biological mechanisms by which other cardiovascular risk factors (eg, aging, hypertension, diabetes mellitus, and chronic kidney disease) cause arterial stiffness, with a particular focus on recent advances regarding nuclear mechanotransduction, mitochondrial oxidative stress, metabolism and dyslipidemia, genome mutations, and epigenetics. Targeting these different molecular pathways at different time of cardiovascular risk factor exposure may be a novel approach for discovering drugs to reduce arterial stiffening without affecting artery strength and normal remodeling.

Mechanical stability of αT-catenin and its activation by force for vinculin binding

αT (Testes)-catenin, a critical factor regulating cell-cell adhesion in the heart, directly couples the cadherin-catenin complex to the actin cytoskeleton at the intercalated disk (ICD), a unique cell-cell junction that couples cardiomyocytes. Loss of αT-catenin in mice reduces plakophilin2 and connexin 43 recruitment to the ICD. Since αT-catenin is subjected to mechanical stretch during actomyosin contraction in cardiomyocytes, its activity could be regulated by mechanical force. To provide insight in how force regulates αT-catenin function, we investigated the mechanical stability of the putative, force-sensing middle (M) domain of αT-catenin and determined how force impacts vinculin binding to αT-catenin. We show that 1) physiological levels of force, <15 pN, are sufficient to unfold the three M domains; 2) the M1 domain that harbors the vinculin-binding site is unfolded at ∼6 pN; and 3) unfolding of the M1 domain is necessary for high-affinity vinculin binding. In addition, we quantified the binding kinetics and affinity of vinculin to the mechanically exposed binding site in M1 and observed that αT-catenin binds vinculin with low nanomolar affinity. These results provide important new insights into the mechanosensing properties of αT-catenin and how αT-catenin regulates cell-cell adhesion at the cardiomyocyte ICD.

ZNF488 is an independent prognostic indicator in nasopharyngeal carcinoma and promotes cell adhesion and proliferation via collagen IV/FAK/AKT/Cyclin D1 pathway

Background: ZNF488 acts as an oncogene which promotes cell invasion and endows tumor cells stem cell capacity in nasopharyngeal carcinoma (NPC), but its correlation with clinicopathologic characteristics and patients' survival in NPC remain undefined. Methods: In this study, 158 cases of confirmed NPC were subjected to immunohistochemistry staining for evaluating endogenous expression. Kaplan-Meier method and log-rank test were used to estimate the survival rates. The relationship between ZNF488 and clinicopathological characteristics was statistically calculated by chi-squared test, univariate and multivariate analysis. In addition, adhesion assay, MTT and colony formation assays were performed for measuring adhesion and proliferation capacity. Cell cycle analysis via flow cytometry was conducted to explore cell cycle distribution. Western blot was used to detect pathway protein levels, and the pFAK (Y397) kit was used for focal adhesion kinase (FAK) activation. Results: We demonstrated that high expression of ZNF488 was significantly correlated with locoregional failure (P=0.018) and distant metastasis (P=0.001). Patients with high ZNF488 expression had poorer overall survival (P<0.001), loco-regional recurrence-free survival (P<0.001), distance metastasis-free survival (P<0.001) and progression-free survival (P<0.001) than those with low ZNF488 group. Multivariate analysis showed that ZNF488 expression was an independent prognostic indicator for predicting NPC patients' survival (HR, 3.314; 95% CI, 1.489-7.386; P=0.003). Additionally, ZNF488-induced collagen IV/FAK/AKT to enhance adhesion ability meanwhile led to the upregulation of Cyclin D1 to facilitate cell proliferation through promoting cell cycle progression and inhibition of apoptosis through caspase-independent way. Conclusion: These results reveal that ZNF488, as an independent prognostic indicator, promotes cell adhesion and proliferation through collagen IV/FAK/AKT/Cyclin D1 pathway in NPC.