Biology subjects

Hamaguchi, M.

Publications and source records attributed to Hamaguchi, M..

4 recordsLinked to original sources

bioRxiv2026

Stromal CTHRC1 protects the valvular interstitium from macrophage-associated inflammatory remodeling and calcification

Background: Calcific aortic valve disease (CAVD) is characterized by progressive inflammatory and fibrocalcific remodeling. Although valvular interstitial cells (VICs) are generally considered to drive fibrosis and osteogenic remodeling, whether injury-activated VICs mount endogenous protective responses that preserve the valvular interstitial microenvironment and restrain calcification remains unknown. Methods: We performed spatial transcriptomic profiling of aortic valves in a mouse model of endothelial injury-induced CAVD to define early injury-responsive programs within the valvular interstitium. The cellular origin and spatial distribution of candidate protective factors were examined by immunohistochemistry and lineage tracing, and their relevance to human disease was assessed using stenotic aortic valves. The functional role of CTHRC1 was investigated using genetic Cthrc1 deficiency combined with longitudinal hemodynamic assessment, histological analysis, and spatial transcriptomic profiling. Results: Spatial transcriptomics identified Cthrc1 as a prominent component of an early injury-induced stromal response in the expanding valvular interstitium. CTHRC1 was strongly expressed in activated VICs within thickened murine valve leaflets and human stenotic aortic valves. Lineage tracing demonstrated that the expanded VIC population arose predominantly from PDGFR{beta}+ resident interstitial cells, with minimal endothelial contribution. Despite comparable early hemodynamic responses to endothelial injury, Cthrc1 deficiency exacerbated chronic valvular calcification. Spatial profiling of Cthrc1-deficient valves revealed pronounced interstitial accumulation of galectin-3+ foamy macrophages, accompanied by mitochondrial respiratory-chain signature loss and cell death-associated pathway activation. These findings indicate that transient CTHRC1 induction after endothelial injury defines an endogenous stromal protective response that preserves the valvular interstitial microenvironment and limits macrophage-associated tissue injury and subsequent dystrophic calcification. Conclusions: Injury-activated VICs are not merely effectors of pathological remodeling, but can engage an endogenous tissue-protective response through CTHRC1. These findings identify a previously unrecognized stromal defense mechanism linking endothelial injury to macrophage-associated inflammatory remodeling and dystrophic calcification and suggest CTHRC1-dependent stromal protection as a potential therapeutic axis for limiting CAVD progression.

molecular biology↗

bioRxiv2025

Osteochondrogenic Transdifferentiation of Vascular Smooth Muscle Cells and Microenvironmental Dynamics in Medial Arterial Calcification

BackgroundVascular calcification, particularly medial arterial calcification (MAC), considerably affects cardiovascular mortality. Current treatments are limited because of the unclear molecular mechanisms of MAC. This study aimed to establish an MAC mouse model using O-ring-induced transverse aortic constriction (OTAC) and to identify critical genes, pathways, and cellular interactions involved in MAC formation by combining lineage tracing technology and single-cell RNsA sequencing (scRNA-seq). MethodsWe developed an OTAC mouse model to mimic MAC. Adult C57BL/6J male mice underwent OTAC, and subsequent analyses were performed at various intervals. Histological and immunohistochemical evaluations were conducted to observe changes in vascular smooth muscle cells (VSMCs). Lineage tracing was used to confirm the origin of osteochondrogenic cells in the tunica media. Additionally, scRNA-seq was performed to capture the dynamic changes in VSMCs and other cell types involved in MAC development. ResultsOsteochondrogenic cells and the subsequent MAC in OTAC mice were observed using histological evaluations. Immunohistochemistry showed time-dependent decreases in -SMA expression and increases in SOX9 and RUNX2 expression in VSMCs. Lineage tracing using Myh11CreERT2;ROSA26-EGFP mice confirmed that osteochondrogenic cells originated from contractile VSMCs. scRNA-seq confirmed osteochondrogenic transdifferentiation of VSMCs and highlighted dynamic changes in surrounding cells involved in calcification-related and inflammatory processes. ConclusionThe OTAC method enabled a comprehensive understanding of the microenvironmental dynamics during MAC progression at the single-cell level. This powerful model provides a robust platform for future therapeutic intervention research. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/684711v1_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@c64634org.highwire.dtl.DTLVardef@12b0b9aorg.highwire.dtl.DTLVardef@106c5b4org.highwire.dtl.DTLVardef@19dd4f4_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

LUZP1 regulates the constriction velocity of the contractile ring during cytokinesis

There has been a great deal of research on cell division and its mechanisms; however, its processes have not yet been entirely elucidated. To find novel proteins that regulate cell division, we performed the screening using siRNAs and/or the expression plasmid of the target genes and identified leucine zipper protein 1 (LUZP1). Recent studies have shown that LUZP1 interacts with various proteins and stabilizes the actin cytoskeleton; however, the function of LUZP1 in mitosis is not known. In this study, we found that LUZP1 colocalized with the chromosomal passenger complex (CPC) at the centromere in metaphase and at the central spindle in anaphase and that these LUZP1 localizations were regulated by CPC activity and kinesin family member 20A (KIF20A). Mass spectrometry analysis identified that LUZP1 interacted with death-associated protein kinase 3 (DAPK3), one regulator of the cleavage furrow ingression in cytokinesis. In addition, we found that LUZP1 also interacted with myosin light chain 9 (MYL9), a substrate of DAPK3, and comprehensively inhibited MYL9 phosphorylation by DAPK3. In line with a known role for MYL9 in the actin-myosin contraction, LUZP1 suppression accelerated the constriction velocity at the division plane in our timelapse analysis. Our study indicates that LUZP1 is a novel regulator for cytokinesis that regulates the constriction velocity of the contractile ring.

cell biology↗

bioRxiv2022

Liver lipophagy ameliorates nonalcoholic steatohepatitis through lysosomal lipid exocytosis

Nonalcoholic steatohepatitis (NASH) is a progressive disorder with aberrant lipid accumulation and subsequent inflammatory and profibrotic response. Therapeutic efforts at lipid reduction via increasing cytoplasmic lipolysis unfortunately worsens hepatitis due to toxicity of liberated fatty acid. An alternative approach could be lipid reduction through autophagic disposal, i.e., lipophagy. We engineered a synthetic adaptor protein to induce lipophagy, combining a lipid droplet-targeting signal with optimized LC3-interacting domain. Activating hepatocyte lipophagy in vivo strongly mitigated both steatosis and hepatitis in a diet-induced mouse NASH model. Mechanistically, activated lipophagy promoted the excretion of lipid from hepatocytes via lysosomal exocytosis, thereby suppressing harmful intracellular accumulation of nonesterified fatty acid. A high-content compound screen identified alpelisib and digoxin, clinically-approved compounds, as effective activators of lipophagy. Administration of alpelisib or digoxin in vivo strongly inhibited the transition to steatohepatitis. These data thus identify lipophagy as a promising therapeutic approach to prevent NASH progression.

cell biology↗