👤 Chikara Ueki

Fibroblast growth factor 2 (FGF2)regulates signal transduction by forming complexes with its receptors, FGF receptors (FGFRs), and heparan sulfate (HS), playing a crucial role in biological systems. Although HS has been suggested to modulate FGF/FGFR signaling as a coreceptor, multiple hypotheses exist regarding how HS affects FGF/FGFR signaling and the mechanism remains unclear. Herein, to highlight the role of FGF2/HS interaction in FGF2/FGFR1 signaling, FGF2 mutants with reduced HS-binding affinity are rationally designed through in silico analysis. These FGF2 mutants exhibit reduced HS affinity by more than two orders of magnitude while maintaining binding affinity to FGFR1. In addition, these mutants retain their thermal stability. Cellular assays using the FGF2 mutant suggest that, contrary to previous reports, the contribution of the FGF2/HS interaction in FGF2/FGFR1 signaling may be limited. The mutant FGFs that specifically alter the interaction with HS, achieved in this study, would contribute to an understanding of the role of FGF/HS interaction in FGF/FGFR signaling. Show less

DNA aptamers have attracted attention as an alternative modality for biomolecules due to their excellent target binding specificity and thermal stability, and they are also expected to be applied as artificial agonists for receptor proteins. DNA aptamer agonist TD0 targeting the receptor of fibroblast growth factor (FGFR), which plays an important role in the fields of wound healing and regenerative medicine, has been reported to induce cellular responses as well as its native ligands. However, it was also noted that there were some different responses upon long-term stimulation, suggesting that the intracellular signals induced by DNA aptamer agonist TD0 are different from those of natural ligands. In this paper, we comprehensively analyzed the intracellular signals induced by DNA aptamer agonist TD0 targeting FGFR1, and compared them with those by natural protein ligand FGF2. It was found that the intracellular signals were highly similar for short-term stimulation. On the other hand, the receptor and the downstream cellular signals showed different activation behaviors for long-time stimulation. Evaluating the stability and sustained activity of DNA aptamer agonist TD0 and FGF2 in the medium suggested that ligand stability may be important in properly regulating cellular responses. Show less

Epicardial adipose tissue (EAT) is known to affect atherosclerosis and coronary artery disease (CAD) pathogenesis, persistently releasing pro-inflammatory adipokines that affect the myocardium and coronary arteries. Angiopoietin-like 4 (ANGPTL4) is a protein secreted from adipose tissue and plays a critical role in the progression of atherosclerosis. Here, the expression of ANGPTL4 in EAT was investigated in CAD subjects. Thirty-four consecutive patients (13 patients with significant CAD; 21 patients without CAD) undergoing elective open-heart surgery were recruited. EAT and pericardial fluid were obtained at the time of surgery. mRNA expression and ANGPTL4 and IL-1β levels were evaluated by qRT-PCR and ELISA. The expression of ANGPTL4 (p = 0.0180) and IL-1β (p < 0.0001) in EAT significantly increased in the CAD group compared to that in the non-CAD group and positively correlated (p = 0.004). Multiple regression analysis indicated that CAD is a contributing factor for ANGPTL4 expression in EAT. IL-1β level in the pericardial fluid was significantly increased in patients with CAD (p = 0.020). Moreover, the expression of ANGPTL4 (p = 0.004) and IL-1β (p < 0.001) in EAT was significantly increased in non-obese patients with CAD. In summary, ANGPTL4 expression in EAT was increased in CAD patients. Show less