👤 Yuna Tanimoto

Pacific salmon (Oncorhynchus spp.) rely on olfactory information learned in their natal rivers to guide their homing migration. Although molecules associated with synaptic plasticity show marked changes in the olfactory system during periods linked to imprinting, the contribution of brain-derived neurotrophic factor (BDNF/Bdnf), a key regulator of neural development and plasticity, has not been fully examined in salmonids. In this study, we isolated the complete coding sequence of masu salmon (O. masou) pro-bdnf and analyzed its expression profile across the olfactory system using wild individuals at multiple developmental stages. The deduced amino acid sequence of masu salmon pro-Bdnf was highly conserved among vertebrates. Pro-bdnf mRNA was strongly expressed in under-yearling parr prior to smoltification, particularly in the olfactory rosette and olfactory bulb at the sensitive period for imprinting. In the telencephalon, a higher olfactory center homologous to the mammalian cerebrum, pro-bdnf expression remained stable across stages, consistent with ongoing neurogenesis in this region. These results provide molecular evidence that pro-bdnf expression mirrors developmental changes in the olfactory system and support the idea that Bdnf contributes to the formation and refinement of olfactory circuits essential for imprinting and homing in Pacific salmon. Show less

Neuroblastoma (NB), a common childhood solid tumor, is the leading cause of childhood cancer deaths. Transgelin (TAGLN) is an actin-binding protein of the calponin family, and it is involved in cell motility and migration. The TAGLN gene expression was induced in NB cell lines, such as GOTO, SK-N-SH, and TGW, by gene overexpression using a retroviral Tet-On inducible expression system, and was repressed by RNA interference (RNAi) treatment. TAGLN overexpression repressed cell growth and migration and induced cell arrest and differentiation. On the other hand, RNAi-mediated TAGLN repression activated cell growth. Cells overexpressing TAGLN showed decreased levels of undifferentiated cell markers, such as SOX2, OCT4, KLF4, and ID2. Single-cell analysis after TAGLN overexpression revealed a distinguishable cluster characterized by expression of POSTM, APOE, PDGFRA, IGFBP3, SMAD5, and IGFBP7. In TH-MYCN mice, which have a high frequency of NB development, Tagln overexpression by induction of the murine Tagln gene significantly reduced tumor formation and prolonged survival. In conclusion, these in vitro and in vivo analyses suggest that TAGLN is a candidate tumor suppressor gene in NB. Show less

Achaete-scute family bHLH transcription factor 2 (ASCL2) is highly expressed in hepatoblastoma (HB) tissues, but its role remains unclear. Thus, biological changes in the HB cell line HepG2 in response to induced ASCL2 expression were assessed. ASCL2 expression was induced in HepG2 cells using the Tet-On 3G system, which includes doxycycline. Cell viability, proliferation activity, mobility, and stemness were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, colony-formation, migration, invasion, and sphere-formation assays. Quantitative reverse-transcription polymerase chain reaction was used to assess the expression of markers for proliferation (CCND1 and MYC), epithelial-mesenchymal transition (EMT; SNAI1, TWIST1, and ZEB1), mesenchymal-epithelial transition (CDH1), and stemness (KLF4, POU5F1, and SOX9). Compared with the non-induced HepG2 cells, cells with induced ASCL2 expression showed significant increases in viability, colony number, migration area (%), and sphere number on days 7, 14, 8, and 7, respectively, and invasion area (%) after 90 h. Furthermore, induction of ASCL2 expression significantly upregulated CCND1, MYC, POU5F1, SOX9, and KLF4 expression on days 2, 2, 3, 3, and 5, respectively, and increased the ratios of SNAI1, TWIST1, and ZEB1 to CDH1 on day 5. ASCL2 promoted the formation of malignant phenotypes in HepG2 cells, which may be correlated with the upregulation of the Wnt signaling pathway-, EMT-, and stemness-related genes. ASCL2 activation may therefore be involved in the progression of HB. Show less

Hypertrophic cardiomyopathy (HCM) and restrictive cardiomyopathy (RCM) present a high risk for sudden cardiac death in pediatric patients. The aim of this study was to identify disease-associated genetic variants in Japanese patients with pediatric HCM and RCM. We analyzed 67 cardiomyopathy-associated genes in 46 HCM and 7 RCM patients diagnosed before 16 years of age using a next-generation sequencing system. We found that 78% of HCM and 71% of RCM patients carried disease-associated genetic variants. Disease-associated genetic variants were identified in 80% of HCM patients with a family history and in 77% of HCM patients with no apparent family history (NFH). MYH7 and/or MYBPC3 variants comprised 76% of HCM-associated variants, whereas troponin complex-encoding genes comprised 75% of the RCM-associated variants. In addition, 91% of HCM patients with implantable cardioverter-defibrillators and infant cases had NFH, and the 88% of HCM patients carrying disease-associated genetic variants were males who carried MYH7 or MYBPC3 variants. Moreover, two disease-associated LAMP2, one DES and one FHOD3 variants, were identified in HCM patients. In this study, pediatric HCM and RCM patients were found to carry disease-associated genetic variants at a high rate. Most of the variants were in MYH7 or MYPBC3 for HCM and TNNT2 or TNNI3 for RCM. Show less

gp130-dependent signaling is known to play a critical role in the onset of heart failure. In that regard, cardiotrophin-1 (CT-1) activates several signaling pathways via gp130, and induces hypertrophy in neonatal rat cardiomyocytes. Among the mediators activated by CT-1, STAT3 is thought to be important for induction of cell hypertrophy, though its precise function in the CT-1 signaling pathway is not fully understood. In the present study, therefore, to better understand the significance of STAT3 activity in CT-1 signaling, we infected cultured cardiomyocytes with adenoviral vectors harboring a dominant-negative STAT3 mutant or one of two endogenous negative regulators of cytokine signaling via the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathways [suppressor of cytokine signaling (SOCS) 1 and 3] and then examined their effects on three indexes of CT-1-induced cell hypertrophy: protein synthesis, secretion of brain natriuretic peptide and changes in cell surface area. In control cells, CT-1-induced both STAT3 phosphorylation and cell hypertrophy. Overexpression of dominant-negative STAT3 mutant suppressed CT-1-induced STAT3 phosphorylation, but did not affect cell hypertrophy. On the other hand overexpression of SOCS1 or SOCS3 inhibited both CT-1-induced STAT3 phosphorylation and cell hypertrophy. CT-1 also induced phosphorylations of ERK1/2 and ERK5 in cardiomyocytes, and those, too, were suppressed by overexpression of SOCSs. CT-1-induced cell hypertrophy was suppressed by overexpression of a dominant-negative MEK5 mutant, and not by overexpression of a dominant-negative MEK1 mutant. These findings indicate that the major pathway responsible for the hypertrophic responses to CT-1 is not JAK-STAT3 pathway nor MEK1-ERK1/2 pathway, but MEK5-ERK5 pathway. Show less