Biology subjects

Kinjo, K.

Publications and source records attributed to Kinjo, K..

3 recordsLinked to original sources

bioRxiv2026

IF1 restrains excessive elevation of the mitochondrial membrane potential and safeguards the epithelial state of human induced pluripotent stem cells

Human pluripotent stem cells (hPSCs) rely on glycolysis and exhibit low mitochondrial respiration, conditions under which F1Fo ATP synthase tends to run in reverse, hydrolyzing ATP. ATP synthase inhibitory factor subunit 1 (IF1) inhibits F1Fo-mediated ATP hydrolysis, but its significance in glycolytic hPSCs remains unclear. Here, we show that stable IF1 knockdown (IF1-KD) in human induced pluripotent stem cells (hiPSCs) enhanced mitochondrial ATP hydrolysis and elevated the mitochondrial membrane potential ({Delta}{Psi}m). Markers of the undifferentiated state were largely maintained, whereas IF1-KD cells exhibited reduced epithelial characteristics and a partial epithelial-mesenchymal transition (EMT)-like state. IF1-KD cells also showed enhanced store-operated Ca2 entry (SOCE) and increased nuclear NFATc3. Pharmacological reduction of {Delta}{Psi}m attenuated SOCE, whereas NFATc3 overexpression reproduced key features of the EMT-like expression pattern. Endogenous IF1 therefore acts as a constitutive restraint on reverse-mode F1Fo activity, limiting excessive {Delta}{Psi}m and downstream SOCE-NFATc3 signaling and safeguarding the epithelial state of hPSCs.

Cell Biology↗

bioRxiv2022

Targeted single-cell genomics reveals novel host adaptation strategies of the symbiotic bacteria Endozoicomonas in Acropora tenuis coral

Endozoicomonas bacteria symbiose with various marine organisms and are known to be beneficial for coral health. However, genome analysis of coral-associated Endozoicomonas has been limited owing to the difficulty in cultivation and metagenomic approach by contamination of host-derived sequences. In this study, we applied a novel single-cell genomics technique using droplet microfluidics to obtain single-cell amplified genome (SAGs) for coral-associated Endozoicomonas spp. genome. We obtained seven novel Endozoicomonas genomes from Acropora tenuis coral. These genomes revealed that Endozoicomonas bacteria played host-associated functions in host corals and had undergone independent host-adaptive evolution in different clades. These adaptive evolutions were mediated by host-derived eukaryotic-like genes, some of which were speculated to influence host immune mechanisms. These genes are speculated to enhance coral tolerance to environmental stresses. This study suggests the possibility of host adaptation of Endozoicomonas spp. in symbiosis with corals and their contribution to coral bleaching tolerance.

microbiology↗

bioRxiv2020

Color morphs of the coral, Acropora tenuis, show different responses to environmental stress and different expression profiles of fluorescent-protein genes

Corals of the family Acroporidae are key structural components of reefs that support the most diverse marine ecosystems. Due to increasing anthropogenic stresses, coral reefs are in decline. Along the coast of Okinawa, Japan, three different color morphs of Acropora tenuis have been recognized for decades. These include brown (N morph), yellow-green (G) and purple (P) forms. The tips of axial coral polyps exhibit specific fluorescence spectra. This attribute is inherited asexually, and color morphs do not change seasonally. In Okinawa Prefecture, during the summer of 2017, the N and P morphs experienced bleaching, in which some N morphs died while P morphs recovered. In contrast, G morphs successfully withstood the stress. Symbiotic dinoflagellates are essential symbiotic partners of scleractinian corals. Photosynthetic activity of symbionts was reduced in July in N and P morphs; however, the three color-morphs host similar sets of Clade-C zoothanthellae, suggesting that beaching of N and P morphs cannot be attributed to differences in symbiont clades. The decoded Acropora tenuis genome includes five genes for green fluorescent proteins (GFP), two for cyan fluorescent proteins (CFP), three for red fluorescent proteins (RFP), and seven genes for chromoprotein (ChrP). A summer survey of gene expression profiles demonstrated that (a) expression of CFP and REP was quite low in all three morphs, (b) P morphs expressed higher levels of ChrP, (c) both N and G morphs expressed GFP highly, and (d) GFP expression was reduced in N morphs, compared to G morphs, which maintained higher levels of GFP expression throughout the summer. Although further studies are required to understand the biological significance of these color morphs of Acropora tenuis, our results suggest that thermal stress resistance is modified by genetic mechanisms that coincidentally lead to diversification of color morphs.

evolutionary biology↗