Biology subjects

Oikawa, T.

Publications and source records attributed to Oikawa, T..

3 recordsLinked to original sources

bioRxiv2024

Spatial confinement induces reciprocating migration of epidermal keratinocytes and forms triphasic epithelia

Epithelial cells undergo epithelial-mesenchymal transition (EMT) during migration and regain their epithelial phenotype in the post-migration phase (mesenchymal-epithelial transition; MET). We established an experimental system that reproduces a three-compartment epithelial structure comprising the original epithelium, its EMT state, and its MET state. Keratinocytes (KCs), skin epithelial cells, placed on a microporous membrane migrated through 3.0-{micro}m or larger micropores. The 3.0-{micro}m-pored membrane induced an epithelial structure with three distinct states: stratified KCs above the membrane, KCs showing EMT within the micropores, and a new stratified epithelium under the membrane. The membrane with larger micropores failed to maintain the three-compartment epithelial structure. Live imaging revealed that KCs moved in an oscillatory manner, with actin-rich filopodia-like structures extending into and out of the 3.0-{micro}m micropores, while the cells migrated unidirectionally into larger micropores. Piezo1 and keratin 6 were identified as negative modulators of KC entry into and exit from the 3.0-{micro}m micropores. These results demonstrate that non-cancerous epithelial cells migrate through confined spaces in an oscillatory manner, which might contribute to the formation of a three-compartment epithelial structure that recapitulates key aspects of wound healing.

cell 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↗