Biomedical subjects

Seitaro Nomura

Publications and source records attributed to Seitaro Nomura.

3 recordsLinked to original sources

PubMed2026

Hox/Meis-dependent gene-regulatory transition underlies cardiopharyngeal neural crest diversification.

Neural crest cells (NCCs) are multipotent migratory cells essential for cardiac development, yet the lineage trajectories and gene regulatory networks underlying their differentiation in the cardiopharyngeal region remain unclear. Here, we integrate single-cell RNA-seq, spatial transcriptomics, and multiomic analyses to construct a comprehensive map of NCC lineages in developing mouse cardiopharyngeal tissues. We identify a transition from Hox-positive pharyngeal NCCs to Hox-negative intracardiac populations associated with the outflow tract cushion, accompanied by a shift in Meis transcription factor binding and gene-regulatory network architecture. By contrast, NCCs forming the aorticopulmonary septum and great vessel smooth muscle retain distinct Hox-codes. A Meis2-Sox9-Scx gene-regulatory network defines a skeletogenic progenitor-like intermediate state that gives rise to coronary artery smooth muscle and semilunar valves. Our findings suggest that the loss of Hox-dependent regional identity enables pharyngeal NCCs to acquire new fates upon entering the cardiac cushion, providing insight into the developmental origins of coronary and valvular calcification.

Journal Article↗

PubMed2026

Vitamin D Pathway Activation Reduces Cardiomyocyte DNA Damage and Improves Cardiac Contractility in Preclinical Models.

BACKGROUND: In heart failure (HF), DNA damage caused by various external stressors contributes to cardiac dysfunction through the activation of DNA damage response pathways. To date, no clinical strategies have been established to restore cardiac function by reducing accumulated DNA damage. We previously found that vitamin D improved contractility in lamin A/C (LMNA) p.Q353R-mutant induced pluripotent stem (iPS) cell-derived cardiomyocytes (iPSCMs), but whether this effect extends to other LMNA variants and in vivo models remained uncertain. OBJECTIVES: The objective of the study was to evaluate the association of vitamin D pathway activation with cardiomyocyte phosphorylated histone H2AX (γH2AX) foci and contractile phenotypes in patient-derived iPSCMs and mouse models of HF. METHODS: iPS cell lines were generated from dilated cardiomyopathy patients carrying the LMNA p.R225X mutation, and the effects of vitamin D treatment on γH2AX foci and cardiomyocyte contractility were evaluated. In addition, the effects of the vitamin D analog paricalcitol were evaluated in Lmna p.R225X mice and in a pressure overload mouse model of HF. RESULTS: Consistent with previous findings, vitamin D treatment reduced γH2AX foci in cardiomyocytes derived from LMNA p.R225X mutant iPS cells through upregulating the expression of DNA repair factors, and improved contractility in these iPSCMs. Furthermore, paricalcitol reduced γH2AX foci and attenuated cardiac dysfunction in both Lmna p.R225X mice and pressure overload HF model mice. CONCLUSIONS: Vitamin D pathway activation improved contractile phenotypes across complementary preclinical models and was accompanied by reduced γH2AX foci or related transcriptional changes. These findings support further mechanistic and preclinical investigation.

DNA damage↗

PubMed2026

Histological Determinants of Atrial Dysfunction in Patients With Atrial Fibrillation.

BACKGROUND: Atrial fibrillation (AF) is associated with diverse histological abnormalities, but their contributions to atrial dysfunction and functional recovery remain unclear. METHODS: In a discovery cohort of 375 patients with nonvalvular AF undergoing catheter ablation, atrial biopsy samples were quantitatively analyzed for fibrosis, intercellular space expansion, myofibrillar loss, myocardial nuclear density, and amyloid deposition. Left atrial reservoir strain (LASr) was assessed as a measure of atrial function during sinus rhythm (Group 1) or AF (Group 2) at the time of echocardiography. Functional recovery was defined as the change in LASr 12 months after ablation. Findings were validated in an independent cohort of 191 patients with AF. A subset of samples was additionally analyzed for DNA damage markers, poly(ADP-ribose), and phosphorylated histone H2A.X. RESULTS: LASr improved significantly after ablation in Group 2 but not in Group 1. Multivariable analyses identified greater fibrosis, reduced myocardial nuclear density, and advanced amyloid deposition as significant determinants of impaired atrial function in both groups and of limited postablation functional recovery in Group 2 (all P<0.01). Amyloid deposition was also significantly associated with adverse clinical outcomes. Decision-tree models incorporating LASr accurately identified advanced amyloid deposition in both cohorts (accuracy, 94%-96%). DNA damage markers were inversely associated with myocardial nuclear density and positively associated with cardiomyocyte hypertrophy. CONCLUSIONS: Fibrosis, DNA damage-associated reduction in myocardial nuclear density, and advanced atrial amyloidosis are key determinants of atrial dysfunction and impaired postablation functional recovery in patients with AF. LASr enables noninvasive identification of advanced atrial amyloidosis.

Humans↗