Naoki Goshima

Abstract Understanding protein subcellular localization and its dynamic changes is crucial for elucidating cellular function and disease mechanisms, particularly under stress conditions, where protein localization changes can modulate cellular responses. Currently available databases provide insights into protein localization under steady-state conditions; however, stress-related dynamic localization changes remain poorly understood. Here, we present the Localizatome, a comprehensive database that captures stress-induced protein localization dynamics in living cells. Using an original high-throughput microscopy system and machine learning algorithms, we analysed the localization patterns of 10 287 fluorescent protein-fused human proteins in HeLa cells before and after exposure to oxidative stress. Our analysis revealed that 1910 proteins exhibited oxidative stress-dependent localization changes, particularly forming distinct foci. Among them, there were stress granule assembly factors and autophagy-related proteins, as well as components of various signalling pathways. Subsequent characterization identified some specific amino acid motifs and intrinsically disordered regions associated with stress-induced protein redistribution. The Localizatome provides open access to these data through a web-based interface, supporting a wide range of studies on cellular stress response and disease mechanisms. Database URL https://localizatome.embrys.jp/

Objective Epitope spreading (ES), involving autoantibodies, plays a crucial role in the development and persistence of autoimmune reactions in various autoimmune diseases. This study aimed to investigate the relationship between ES of anti–RNA polymerase III (RNAP III) antibodies (ARAs) and the clinical manifestations of systemic sclerosis (SSc). Methods We investigated whether intermolecular ES occurs in the subunits of the RNAP III complex and whether intramolecular ES targets the major antigen, RNA polymerase III subunit A (RPC1), in patients with SSc. To achieve this, we synthesized 17 full‐length subunit proteins of the RNAP III complex and 5 truncated forms of RPC1 in vitro using a wheat germ cell‐free translation system. Subsequently, we prepared antigen‐binding plates and measured autoantibodies in the serum of patients with SSc. Results Autoantibodies against different RNAP III complex subunits were found in patients who were ARA‐positive with SSc. The intermolecular ES indicators significantly correlated with the modified Rodnan skin thickness score (mRSS) and surfactant protein‐D, a biomarker of interstitial lung disease. However, the extent of disease on high‐resolution computed tomography or pulmonary function tests did not show any significant correlation. Intramolecular ES indicator against RPC1 were significantly correlated with mRSS and renal crisis. Furthermore, longitudinal assessment of ES in RNAP III complex subunits correlated with mRSS and exhibited potential as a disease activity biomarker. Conclusion Our findings indicate a correlation between ES levels and the severity of skin sclerosis or the risk of other complications in SSc. This study suggests that measuring ES in SSc serves as a novel biomarker for disease activity. image

Recent studies have reported the presence of autoantibodies against zinc finger and SCAN domain-containing protein 1 (ZSCAN1) in the sera of patients with rapid-onset obesity with hypoventilation, hypothalamic and autonomic dysregulation (ROHHAD) syndrome associated with neuroendocrine tumors, suggesting immunologic and paraneoplastic processes as the pathologic underpinnings. Moreover, several hypothalamic regions, including the subfornical organ (SFO), were reported to exhibit antibody reactivity in a patient with ROHHAD syndrome not associated with a tumor. Whether ROHHAD syndrome not associated with a tumor is associated with anti-ZSCAN1 autoantibodies remains unclear. We used a comprehensive protein array analysis to identify candidate molecules in the sera of patients with ROHHAD syndrome and identified ZSCAN1 as a target antigen. We also found that ZSCAN1 was co-expressed at the site of antibody reactivity to the IgG in the patient serum observed in mouse SFOs and an enzyme-linked immunosorbent assay showed that >85% of the patients with ROHHAD syndrome were positive for anti-ZSCAN1 autoantibodies. These results suggest anti-ZSCAN1 autoantibodies as a feasible diagnostic marker in ROHHAD syndrome regardless of the presence of a tumor.