Hiroki Hayashi

Bio: Hiroki Hayashi is an academic researcher from Osaka University. The author has contributed to research in topics: Epitope & Endothelial stem cell. The author has an hindex of 10, co-authored 33 publications receiving 439 citations.

Ubiquitin Carboxyl-Terminal Hydrolase L1, a Novel Deubiquitinating Enzyme in the Vasculature, Attenuates NF-κB Activation

Abstract: Objective— We identified a ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) gene, which encodes a deubiquitinating enzyme and is expressed in the vasculature, by functional screening of a human endothelial cell (EC) cDNA library UCHL1 is expressed in neurons, and abnormalities in UCHL1 are responsible for inherited Parkinson’s disease via its effects on the ubiquitin-proteasome system Therefore, the goal of present study was to clarify the role of the UCHL1 gene in vascular remodeling by evaluating nuclear factor-κB (NF-κB) inactivation in ECs and vascular smooth muscle cells (VSMCs) Methods and Results— From Northern blot and immunohistochemical analysis, the UCHL1 gene was endogenously expressed in vascular ECs, VSMCs, and brain tissue Expression of UCHL1 was markedly increased in the neointima of the balloon-injured carotid artery and was also present in atherosclerotic lesions from human carotid arteries Overexpression of the UCHL1 gene significantly attenuated tumor necrosis factor (TNF)-α–induced NF-κB activity in vascular cells and increased inhibitor of kappa B-α (IκB-α), possibly through the attenuation of IκB-α ubiquitination, leading to decreased neointima in the balloon-injured artery In contrast, knockdown of UCHL1 by small interfering RNA resulted in increased NF-κB activity in VSMCs Conclusions— These data suggest that UCHL1 may partially attenuate vascular remodeling through inhibition of NF-κB activity

Zyxin mediates actin fiber reorganization in epithelial-mesenchymal transition and contributes to endocardial morphogenesis.

Abstract: Epithelial–mesenchymal transition (EMT) confers destabilization of cell–cell adhesion and cell motility required for morphogenesis or cancer metastasis. Here we report that zyxin, a focal adhesion-associated LIM protein, is essential for actin reorganization for cell migration in TGF-β1–induced EMT in normal murine mammary gland (NMuMG) cells. TGF-β1 induced the relocation of zyxin from focal adhesions to actin fibers. In addition, TGF-β1 up-regulated zyxin via a transcription factor, Twist1. Depletion of either zyxin or Twist1 abrogated the TGF-β1–dependent EMT, including enhanced cell motility and actin reorganization, indicating the TGF-β1-Twist1-zyxin signal for EMT. Both zyxin and Twist1 were predominantly expressed in the cardiac atrioventricular canal (AVC) that undergoes EMT during heart development. We further performed ex vivo AVC explant assay and revealed that zyxin was required for the reorganization of actin fibers and migration of the endocardial cells. Thus, zyxin reorganizes actin fibers and enhances cell motility in response to TGF-β1, thereby regulating EMT.

The CD153 vaccine is a senotherapeutic option for preventing the accumulation of senescent T cells in mice

Abstract: Senotherapy targeting for senescent cells is designed to attenuate age-related dysfunction. Senescent T cells, defined as CD4+ CD44high CD62Llow PD-1+ CD153+ cells, accumulate in visceral adipose tissues (VAT) in obese individuals. Here, we show the long-lasting effect of using CD153 vaccination to remove senescent T cells from high-fat diet (HFD)-induced obese C57BL/6J mice. We administered a CD153 peptide-KLH (keyhole limpet hemocyanin) conjugate vaccine with Alhydrogel (CD153-Alum) or CpG oligodeoxynucleotide (ODN) 1585 (CD153-CpG) and confirmed an increase in anti-CD153 antibody levels that was sustained for several months. After being fed a HFD for 10-11 weeks, adipose senescent T cell accumulation was significantly reduced in the VAT of CD153-CpG-vaccinated mice, accompanied by glucose tolerance and insulin resistance. A complement-dependent cytotoxicity (CDC) assay indicated that the mouse IgG2 antibody produced in the CD153-CpG-vaccinated mice successfully reduced the number of senescent T cells. The CD153-CpG vaccine is an optional tool for senolytic therapy.

HIG1, a novel regulator of mitochondrial γ-secretase, maintains normal mitochondrial function

Abstract: The γ-secretase complex (which contains presenilins, nicastrin, anterior pharynx defective-1, and presenilin enhancer-2) cleaves type I transmembrane proteins, including Notch and amyloid precursor protein. Dysregulated γ-secretase activity has been implicated in the pathogenesis of Alzheimer's disease, stroke, atherosclerosis, and cancer. Tight regulation of γ-secretase activity is required for normal physiology. Here, we isolated HIG1 (hypoxia inducible gene 1, domain member 1A) from a functional screen of γ-secretase inhibitory genes. HIG1 was highly expressed in the brain. Interestingly, HIG1 was localized to the mitochondria and was directly bound to γ-secretase components on the mitochondrial membrane in SK-N-SH neuroblastoma cells. Overexpresssion of HIG1 attenuated hypoxia-induced γ-secretase activation on the mitochondrial membrane and the accumulation of intracellular amyloid β. This accumulation was accompanied by hypoxia-induced mitochondrial dysfunction. The latter half domain of HIG1 was req...

Epithelial-mesenchymal transitions: insights from development

Abstract: Epithelial-mesenchymal transition (EMT) is a crucial, evolutionarily conserved process that occurs during development and is essential for shaping embryos. Also implicated in cancer, this morphological transition is executed through multiple mechanisms in different contexts, and studies suggest that the molecular programs governing EMT, albeit still enigmatic, are embedded within developmental programs that regulate specification and differentiation. As we review here, knowledge garnered from studies of EMT during gastrulation, neural crest delamination and heart formation have furthered our understanding of tumor progression and metastasis.

Vascular Smooth Muscle Cells and Arterial Stiffening: Relevance in Development, Aging, and Disease

Abstract: The cushioning function of large arteries encompasses distension during systole and recoil during diastole which transforms pulsatile flow into a steady flow in the microcirculation Arterial stiffness, the inverse of distensibility, has been implicated in various etiologies of chronic common and monogenic cardiovascular diseases and is a major cause of morbidity and mortality globally The first components that contribute to arterial stiffening are extracellular matrix (ECM) proteins that support the mechanical load, while the second important components are vascular smooth muscle cells (VSMCs), which not only regulate actomyosin interactions for contraction but mediate also mechanotransduction in cell-ECM homeostasis Eventually, VSMC plasticity and signaling in both conductance and resistance arteries are highly relevant to the physiology of normal and early vascular aging This review summarizes current concepts of central pressure and tensile pulsatile circumferential stress as key mechanical determinants of arterial wall remodeling, cell-ECM interactions depending mainly on the architecture of cytoskeletal proteins and focal adhesion, the large/small arteries cross-talk that gives rise to target organ damage, and inflammatory pathways leading to calcification or atherosclerosis We further speculate on the contribution of cellular stiffness along the arterial tree to vascular wall stiffness In addition, this review provides the latest advances in the identification of gene variants affecting arterial stiffening Now that important hemodynamic and molecular mechanisms of arterial stiffness have been elucidated, and the complex interplay between ECM, cells, and sensors identified, further research should study their potential to halt or to reverse the development of arterial stiffness

An EMT–Driven Alternative Splicing Program Occurs in Human Breast Cancer and Modulates Cellular Phenotype

Abstract: Epithelial-mesenchymal transition (EMT), a mechanism important for embryonic development, plays a critical role during malignant transformation. While much is known about transcriptional regulation of EMT, alternative splicing of several genes has also been correlated with EMT progression, but the extent of splicing changes and their contributions to the morphological conversion accompanying EMT have not been investigated comprehensively. Using an established cell culture model and RNA–Seq analyses, we determined an alternative splicing signature for EMT. Genes encoding key drivers of EMT–dependent changes in cell phenotype, such as actin cytoskeleton remodeling, regulation of cell–cell junction formation, and regulation of cell migration, were enriched among EMT–associated alternatively splicing events. Our analysis suggested that most EMT–associated alternative splicing events are regulated by one or more members of the RBFOX, MBNL, CELF, hnRNP, or ESRP classes of splicing factors. The EMT alternative splicing signature was confirmed in human breast cancer cell lines, which could be classified into basal and luminal subtypes based exclusively on their EMT–associated splicing pattern. Expression of EMT–associated alternative mRNA transcripts was also observed in primary breast cancer samples, indicating that EMT–dependent splicing changes occur commonly in human tumors. The functional significance of EMT–associated alternative splicing was tested by expression of the epithelial-specific splicing factor ESRP1 or by depletion of RBFOX2 in mesenchymal cells, both of which elicited significant changes in cell morphology and motility towards an epithelial phenotype, suggesting that splicing regulation alone can drive critical aspects of EMT–associated phenotypic changes. The molecular description obtained here may aid in the development of new diagnostic and prognostic markers for analysis of breast cancer progression.