Yuhko Ando-Akatsuka
Suzuka University of Medical Science
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Featured researches published by Yuhko Ando-Akatsuka.
Cell Death & Differentiation | 2005
Maria Zamaraeva; Ravshan Z. Sabirov; Emi Maeno; Yuhko Ando-Akatsuka; S V Bessonova; Yasunobu Okada
Apoptosis is a distinct form of cell death, which requires energy. Here, we made real-time continuous measurements of the cytosolic ATP level throughout the apoptotic process in intact HeLa, PC12 and U937 cells transfected with the firefly luciferase gene. Apoptotic stimuli (staurosporine (STS), tumor necrosis factor α (TNFα), etoposide) induced significant elevation of the cytosolic ATP level. The cytosolic ATP level remained at a higher level than in the control for up to 6 h during which activation of caspase-3 and internucleosomal DNA fragmentation took place. When the STS-induced ATP response was abolished by glucose deprivation-induced inhibition of glycolysis, both caspase activation and DNA laddering were completely inhibited. Annexin V-binding induced by STS or TNFα was largely suppressed by glycolysis inhibition. Thus, it is suggested that the cells die with increased cytosolic ATP, and elevation of cytosolic ATP level is a requisite to the apoptotic cell death process.
Cell Death & Differentiation | 2003
L F Barros; T Kanaseki; Ravshan Z. Sabirov; Shigeru Morishima; J Castro; C X Bittner; Emi Maeno; Yuhko Ando-Akatsuka; Yasunobu Okada
AbstractApoptotic and necrotic blebs elicited by H2O2 were compared in terms of dynamics, structure and underlying biochemistry in HeLa cells and Clone 9 cells. Apoptotic blebs appeared in a few minutes and required micromolar peroxide concentrations. Necrotic blebs appeared much later, prior to cell permeabilization, and required millimolar peroxide concentrations. Strikingly, necrotic blebs grew at a constant rate, which was unaffected throughout successive cycles of budding and detachment. At 1 μm diameter, the necks of necrotic and apoptotic blebs were almost identical. ATP depletion was discarded as a major factor for both types of bleb. Inhibition of ROCK-I, MLCK and p38MAPK strongly decreased apoptotic blebbing but had no effect on necrotic blebbing. Taken together, these data suggest the existence of a novel structure of fixed dimensions at the neck of both types of plasma membrane blebs in epithelial cells. However, necrotic blebs can be distinguished from apoptotic blebs in their susceptibility to actomyosin kinase inhibition.
The Journal of Physiology | 2000
Akihiro Hazama; Hai-Tian Fan; Iskandar F. Abdullaev; Emi Maeno; Shoko Tanaka; Yuhko Ando-Akatsuka; Yasunobu Okada
A hypotonic challenge, but not cAMP stimulation, was found to induce release of ATP measured by the luciferin‐luciferase assay from both the murine mammary carcinoma cell line C127i and C127 cells stably transfected with the cDNA for human cystic fibrosis transmembrane conductance regulator (CFTR) protein (C127/CFTR). CFTR expression augmented swelling‐induced ATP release by 10–20 times under hypotonic conditions (<= 80 % osmolality). Glibenclamide failed to suppress swelling‐induced ATP release from C127/CFTR cells. In contrast, whole‐cell patch‐clamp recordings showed that both the cAMP‐activated ohmic Cl− currents and volume‐sensitive outwardly rectifying (VSOR) Cl− currents were prominently suppressed by glibenclamide. Gd3+ markedly blocked swelling‐induced ATP release but failed to suppress both cAMP‐ and swelling‐activated Cl− currents in the CFTR‐expressing cells. Even after pretreatment and during treatment with Gd3+, VSOR Cl− currents were activated normally. The continuous presence of an ATP‐hydrolysing enzyme, apyrase, in the bathing solution did not prevent activation of VSOR Cl− currents in C127/CFTR cells. The rate of regulatory volume decrease (RVD) in C127/CFTR cells was much faster than that in C127i cells. When apyrase was added to the bathing solution, the RVD rate was retarded in C127/CFTR cells. On balance, the following conclusions can be deduced. First, swelling‐induced ATP release is augmented by expression of CFTR but is not mediated by the CFTR Cl− channel. Second, swelling‐induced ATP release is not mediated by the VSOR Cl− channel. Third, the released ATP facilitated the RVD process but is not involved in the activation of VSOR Cl− channels in C127/CFTR cells.
Pflügers Archiv: European Journal of Physiology | 2002
Yuhko Ando-Akatsuka; Iskandar F. Abdullaev; Elbert L. Lee; Yasunobu Okada; Ravshan Z. Sabirov
Abstract. Transient expression of wild-type human cystic fibrosis transmembrane conductance regulator (CFTR) in HEK293T cells resulted in a profound decrease in the amplitude of volume-sensitive outwardly rectifying Cl– channel (VSOR) current without changing the single-channel amplitude. This effect was not mimicked by expression of the ΔF508 mutant of CFTR, which did not reach the plasma membrane. The VSOR regulation by CFTR was not affected by G551D mutation at first nucleotide-binding domain (NBD1), which is known to impair CFTR interaction with the outwardly rectifying chloride channel, ORCC, epithelial amiloride-sensitive Na-channel, ENaC, and renal potassium channel, ROMK2. The CFTR-VSOR interaction was insensitive to the deletion mutation, ΔTRL, which is known to impair CFTR-PDZ domain binding. In contrast, the G1349D mutant, which impairs ATP binding at NBD2, effectively abolished the down-regulatory effect of CFTR. Furthermore, the K1250M mutation at the Walker A motif and the D1370N mutation at the Walker B motif, both known to impair ATP hydrolysis at NBD2, completely abolished the VSOR regulation by CFTR. Thus, we conclude that an ATP-hydrolysable conformation of NBD2 is essential for the regulation of the VSOR by the CFTR protein, and that VSOR is a first channel regulated by CFTR through its NBD2.
Glia | 2004
Xiao-dong Zhang; Shigeru Morishima; Yuhko Ando-Akatsuka; Nobuyuki Takahashi; Takashi Nabekura; Hana Inoue; Takahiro Shimizu; Yasunobu Okada
Chloride channels play an important role in glial astrocyte function. However, in astrocytes, no chloride channels besides the γ‐aminobutyric acid (GABA)A receptor, glycine receptor, and ClC‐2 chloride channels have been molecularly identified. In this study, we examined the expression of the ClC‐1 chloride channel in rat astrocytic glioma C6 cells and rat primary astrocytes. Five isoforms of ClC‐1, but not skeletal muscle ClC‐1 (SM ClC‐1), were found to be expressed in C6 cells. Comparison with rat SM ClC‐1 showed that common features shared by these isoforms are a short 3′ end with a deletion of the nucleotides from 3115 to 3197 and a substitution of T by C at nucleotides 480 and 1733. Three of the five isoforms, M1, M2, and M3, were produced by partial deletion of ClC‐1 exon 7, partial insertion of ClC‐1 exon 7a, and a TAG insertion at nucleotide 858, respectively. One of the two remaining isoforms, M4, was produced by partial deletion of ClC‐1 exon 8 at nucleotide 937; the other, M5, was the same as SM ClC‐1 except for the short 3′ end and substitutions at the two positions. Only the M5 isoform could be expressed as a functional channel in Xenopus oocytes. This glial isoform exhibited less dependence on voltage and extracellular Cl− than rat SM ClC‐1. However, the anion selectivity sequence and the anthracene‐9‐carboxylic acid (9‐AC) sensitivity of this channel were the same as for SM ClC‐1. Since whole‐cell recordings failed to detect ClC‐1‐like Cl− currents in C6 cells, it appears that the ClC‐1 isoform is functioning in intracellular organelles. In rat primary astrocytes, we found that the M2 isoform as well as two additional distinct isoforms were expressed. The present study showed that astrocytic glial cells express multiple isoforms of the ClC‐1 chloride channel, which has been thought to be expressed almost exclusively in the skeletal muscle.
Journal of Cellular Physiology | 2012
Yuhko Ando-Akatsuka; Takahiro Shimizu; Tomohiro Numata; Yasunobu Okada
After osmotic swelling, cell volume is regulated by a process called regulatory volume decrease (RVD). Although actin cytoskeletons are known to play a regulatory role in RVD, it is not clear how actin‐binding proteins are involved in the RVD process. In the present study, an involvement of an actin‐binding protein, α‐actinin‐4 (ACTN4), in RVD was examined in human epithelial HEK293T cells. Overexpression of ACTN4 significantly facilitated RVD, whereas siRNA‐mediated downregulation of endogenous ACTN4 suppressed RVD. When the cells were subjected to hypotonic stress, the content of ACTN4 increased in a 100,000 × g pellet, which was sensitive to cytochalasin D pretreatment. Protein overlay assays revealed that ABCF2, a cytosolic member of the ABC transporter superfamily, is a binding partner of ACTN4. The ACTN4‐ABCF2 interaction was markedly enhanced by hypotonic stimulation and required the NH2‐terminal region of ABCF2. Overexpression of ABCF2 suppressed RVD, whereas downregulation of ABCF2 facilitated RVD. We then tested whether ABCF2 has a suppressive effect on the activity of volume‐sensitive outwardly rectifying anion channel (VSOR), which is known to mediate Cl− efflux involved in RVD, because another ABC transporter member, CFTR, was shown to suppress VSOR activity. Whole‐cell VSOR currents were largely reduced by overexpression of ABCF2 and markedly enhanced by siRNA‐mediated depletion of ABCF2. Thus, the present study indicates that ACTN4 acts as an enhancer of RVD, whereas ABCF2 acts as a suppressor of VSOR and RVD, and suggests that a swelling‐induced interaction between ACTN4 and ABCF2 prevents ABCF2 from suppressing VSOR activity in the human epithelial cells. J. Cell. Physiol. 227: 3498–3510, 2012.
The Journal of General Physiology | 1999
Akihiro Hazama; Takahiro Shimizu; Yuhko Ando-Akatsuka; Seiji Hayashi; Shoko Tanaka; Emi Maeno; Yasunobu Okada
American Journal of Physiology-cell Physiology | 2009
Abduqodir H. Toychiev; Ravshan Z. Sabirov; Nobuyaki Takahashi; Yuhko Ando-Akatsuka; Hongtao Liu; Takafumi Shintani; Masaharu Noda; Yasunobu Okada
Japanese Journal of Physiology | 2003
Hiromi Uramoto; Nobuyuki Takahashi; Amal K. Dutta; Ravshan Z. Sabirov; Yuhko Ando-Akatsuka; Shigeru Morishima; Yasunobu Okada
Proceedings of Annual Meeting of the Physiological Society of Japan Proceedings of Annual Meeting of the Physiological Society of Japan | 2005
Yuhko Ando-Akatsuka; Takahiro Shimizu; Yasunobu Okada