👤 Masaaki Kitada

Brain-derived neurotrophic factor (BDNF) plays a pivotal role in neuronal development, synaptic plasticity, and cognitive function, and its dysregulation is implicated in various neurodegenerative and neuropsychiatric disorders. To noninvasively monitor dynamic changes in Bdnf expression in vivo, we developed a novel transgenic mouse line, Bdnf-AkaLuc transgenic (Tg) mice, in which the coding region of BDNF was replaced in a BAC transgene with a mutant luciferase, AkaLuc. This luciferase is optimized for the synthetic substrate AkaLumine, which emits near-infrared bioluminescence suitable for deep-tissue imaging. This engineered bioluminescence imaging (BLI) system, termed AkaBLI, enables robust and highly sensitive detection of bioluminescence in the brains of living mice, significantly outperforming our previous Bdnf-Luciferase Tg model. Using this system, we successfully visualized activity-dependent Bdnf mRNA induction in response to pilocarpine-induced status epilepticus. To overcome the limitations of repeated imaging, we identified optimal BLI intervals and established a hairless Bdnf-AkaLuc Tg line, facilitating long-term longitudinal monitoring. Furthermore, by crossing Bdnf-AkaLuc Tg mice with 5xFAD Alzheimer's disease model mice, we successfully visualized reductions in Bdnf expression in the brains of living 5xFAD mice. Our study introduces a powerful tool for noninvasive, continuous visualization of Bdnf regulation under both physiological and disease-related conditions. This imaging approach holds potential for advancing our understanding of BDNF-related brain function and for evaluating therapeutic strategies targeting BDNF in neurological disorders. Show less

Recent studies applying high-throughput sequencing technologies have identified several recurrently mutated genes and pathways in multiple cancer genomes. However, transcriptional consequences from these genomic alterations in cancer genome remain unclear. In this study, we performed integrated and comparative analyses of whole genomes and transcriptomes of 22 hepatitis B virus (HBV)-related hepatocellular carcinomas (HCCs) and their matched controls. Comparison of whole genome sequence (WGS) and RNA-Seq revealed much evidence that various types of genomic mutations triggered diverse transcriptional changes. Not only splice-site mutations, but also silent mutations in coding regions, deep intronic mutations and structural changes caused splicing aberrations. HBV integrations generated diverse patterns of virus-human fusion transcripts depending on affected gene, such as TERT, CDK15, FN1 and MLL4. Structural variations could drive over-expression of genes such as WNT ligands, with/without creating gene fusions. Furthermore, by taking account of genomic mutations causing transcriptional aberrations, we could improve the sensitivity of deleterious mutation detection in known cancer driver genes (TP53, AXIN1, ARID2, RPS6KA3), and identified recurrent disruptions in putative cancer driver genes such as HNF4A, CPS1, TSC1 and THRAP3 in HCCs. These findings indicate genomic alterations in cancer genome have diverse transcriptomic effects, and integrated analysis of WGS and RNA-Seq can facilitate the interpretation of a large number of genomic alterations detected in cancer genome. Show less

17beta-Hydroxysteroid dehydrogenase type 12 (17beta-HSD12) has been shown to be involved in elongation of very long chain fatty acid (VLCFA) as well as in biosynthesis of estradiol (E2). 17beta-HSD12 expression was also reported in breast carcinomas but its functions have remained unknown. In this study, we examined the correlation between mRNA expression profiles determined by microarray analysis and tissue E2 concentrations obtained from 16 postmenopausal breast carcinoma cases. No significant correlations were detected between 17beta-HSD12 expression and E2 concentration. We then immunolocalized this enzyme in 110 cases of invasive ductal carcinoma. 17beta-HSD12 immunoreactivity in breast carcinoma cells was significantly associated with poor prognosis of the patients. We further examined the biological significance of 17beta-HSD12 using cell-based studies. Small interfering RNA-mediated knockdown of 17beta-HSD12 in SK-BR-3 (estrogen receptor-negative breast carcinoma cell line) resulted in significant growth inhibition, which was recovered by the addition of VLCFAs such as arachidonic acid. The status of 17beta-HSD12 immunoreactivity was also correlated with adverse clinical outcome in cyclooxygenase 2 (COX2)-positive breast cancer patients but not in COX2-negative patients. Therefore, these findings indicated that 17beta-HSD12 was not necessarily related to intratumoral E2 biosynthesis, at least in human breast carcinoma, but was rather correlated with production of VLCFAs such as arachidonic acid, which may subsequently be metabolized to prostaglandins by COX2 and result in tumor progression of the patients. Show less