Biology subjects

Onodera, Y.

Publications and source records attributed to Onodera, Y..

4 recordsLinked to original sources

bioRxiv2025

Molecular basis of the autoregulatory mechanism of motor neuron-related splicing factor 30

Motor neuron-related splicing factor 30 (SPF30, also known as SMNDC1) is a paralog of the survival motor neuron protein that regulates the expression of various genes by affecting mRNA splicing. SPF30 has an autoregulatory mechanism that controls its expression. However, the detailed molecular mechanisms determining cellular levels of SPF30 remain unclear. Here, we demonstrated that SPF30 expression was controlled via the negative autoregulatory feedback, whereby increased SPF30 expression caused the inclusion of cassette exon within intron 2 and/or the generation of a newly spliced variant with exon 4a (produced by splicing 17 bp upstream of the canonical intron 3 and exon 4 junctions). Altered transcripts with cassette exon or exon 4a were subjected to nonsense-mediated mRNA decay, leading to reduced SPF30 mRNA levels. Conversely, the loss of SPF30 protein resulted in a drastic reduction in exon 4a inclusion compared to cassette exon inclusion, suggesting that exon 4a inclusion contributes more to adjusting SPF30 expression levels. An in vivo splicing assay designed to reflect exon 4a inclusion levels demonstrated that a short stretch of sequence within exon 4 of SPF30 mRNA was required for exon 4a inclusion. Additionally, the C-terminal region of SPF30 was crucial for the autoregulatory mechanism. Specifically, the C-terminal region of SPF30, including the latter part of -helix and a kink-like structure, was required for binding to RNA containing exon 4a. Collectively, these results reveal the molecular basis of the autoregulatory mechanism underlying SPF30 gene expression.

molecular biology↗

bioRxiv2024

MitoNEET reduces the mitochondrial oxidative phosphorylation during epithelial-mesenchymal transition

Mitochondrial functions range from catabolic to anabolic, which are tightly coordinated to meet cellular demands for proliferation and motility. MitoNEET is a mitochondrial outer membrane protein with a CDGSH domain and is involved in mitochondrial function. Epithelial-to-mesenchymal transition (EMT) is the process in which cells lose their epithelial characteristics and acquire mesenchymal traits, such as motility, which is a vital step for organism development and wound-healing. Cellular motility is associated with high ATP consumption owing to lamellipodia formation, which is supported by upregulated oxidative phosphorylation (OXPHOS) capacity. However, how mitoNEET is involved in the regulation of OXPHOS capacity and subsequent cellular motility remains unclear. Here we show that loss of mitoNEET regulation during EMT impairs both OXPHOS enhancement and cell motility in non-transformed NMuMG mouse mammary gland epithelial cells. We found that mitoNEET is downregulated during EMT, and that the aberrant expression of mitoNEET abolishes the upregulation of OXPHOS, leading to the inhibition of cell motility. Furthermore, we found that mitoNEET topology may be crucial for the regulation of the mitochondrial electron transfer chain, suggesting an additional regulatory pathway for OXPHOS capacity. Our results demonstrate that mitochondrial OXPHOS capacity during EMT is partly regulated by the dynamics of the outer membrane protein. We believe that our findings are the first step towards understanding the mechanisms by which mitochondrial outer membrane protein topology affects organelle functions.

cell biology↗

bioRxiv2023

p53 controls the nuclear entry and epigenetic modification of H3.1 by downregulating nuclear phosphatidic acid

Histones are key molecules of epigenetic regulation and inheritance, and are thought to be chaperoned and transported into the nucleus appropriately prior to being integrated into nucleosomes. H3.1 histone is predominantly synthesized and enters the nucleus during the G1/S phase of the cell cycle, as a new component of duplicating nucleosomes. Here we found that p53 is necessary to secure the normal behavior and modification of H3.1 in the nucleus during the G1/S phase, in which p53 increases C-terminal domain nuclear envelope phosphatase 1 (CTDNEP1) levels and decreases enhancer of zeste homolog 2 (EZH2) levels in the H3.1 interactome. In the absence of p53, H3.1 molecules tended to be tethered at or near the nuclear envelope (NE), where they were predominantly trimethylated at lysine 27 (H3K27me3) by EZH2, without forming nucleosomes. This accumulation was likely caused by the high affinity of H3.1 towards phosphatidic acid (PA). p53 reduced nuclear PA levels by increasing levels of CTDNEP1, which activates lipin to convert PA into diacylglycerol. Induction of the TMEM255A gene by p53 linked p53 with CTDNEP1, in which TMEM255A stabilized CTDNEP1. We moreover found that the cytosolic H3 chaperone HSC70 attenuates the H3.1-PA interaction, and our molecular imaging analyses suggested that H3.1 molecules may be anchored around the NE after their nuclear entry. Our results expand our knowledge of p53 function in regulation of the nuclear behavior of H3.1 during the G1/S phase, in which p53 may primarily target nuclear PA and EZH2.

cell biology↗

bioRxiv2020

Enhancer Remodeling Promotes Tumor-Initiating Activity in NRF2-Activated Non-Small Cell Lung Cancers

Transcriptional dysregulation, which can be caused by genetic and epigenetic alterations, is a fundamental feature of many cancers. A key cytoprotective transcriptional activator, NRF2, is often aberrantly activated in non-small cell lung cancers (NSCLCs) and supports both aggressive tumorigenesis and therapeutic resistance. Herein, we found that persistently activated NRF2 in NSCLCs generates enhancers at gene loci that are not normally regulated by transiently activated NRF2 under physiological conditions. Elevated accumulation of CEBPB in NRF2-activated NSCLCs was found to be one of the prerequisites for establishment of the unique NRF2-dependent enhancers, among which NOTCH3 enhancer was shown to be critical for the promotion of tumor-initiating activity. Enhancer remodeling mediated by NRF2-CEBPB cooperativity promotes tumor-initiating activity and drives malignancy of NRF2-activated NSCLCs via establishment of the NRF2-NOTCH3 regulatory axis.

cancer biology↗