Hanako Hirata

Publications (8)15.36 Total impact

• Article: Autophagy inhibited Ehrlich ascitic tumor cells apoptosis induced by the nitrostyrene derivative compounds: relationship with cytosolic calcium mobilization.

  Andrana K Calgarotto, Gustavo J da Silva Pereira, Alexandre Bechara, Edgar J Paredes-Gamero, Christiano M V Barbosa, Hanako Hirata, Mary L de Souza Queiroz, Soraya S Smaili, Claudia Bincoletto
  [show abstract] [hide abstract]
  ABSTRACT: Apoptosis induction is often associated with increased autophagy, indicating interplay between these two important cellular events in cell death and survival. In this study, the programmed cell death and autophagy induced by two nitrostyrene derivative compounds (NTS1 and NTS2) was studied using the tumorigenic Ehrlich ascitic tumor (EAT) cells. EAT cells were highly sensitive to NTS1 and NTS2 cytotoxicity in a dose-dependent manner. NTS1 and NTS2 IC(50) was less than 15.0μM post 12h incubation. Apoptosis was primarily induced by both compounds, as demonstrated by an increase in Annexin-V positive cells, concurrently with cytochrome c release from mitochondria to cytosol and caspase-3 activation. Although cytosolic Ca(2+) mobilization is involved in autophagy as well as apoptosis in response to cellular stress in many cancer cell types, from the two nitrostyrene derivative compounds studied, mainly NTS1 mobilized this ion and disparate autophagy in EAT cells. These results suggest that EAT induced cell death by NTS1 and NTS2 involved a Ca(2+)-dependent and a Ca(2+)-independent pathways, respectively. In accordance with these results, the treatment of EAT cells with 3 methyladenine (3-MA), an autophagy inhibitor; significantly increased the number of apoptotic cells after NTS1 treatment, suggesting that pharmacological modulation of autophagy augments the NTS1 efficacy. Thus, we denote the importance of studies involving autophagy and apoptosis during pre-clinical studies of new drugs with anticancer properties.
  European journal of pharmacology 03/2012; 678(1-3):6-14. · 2.59 Impact Factor
• Article: Bcl-2 modulates endoplasmic reticulum and mitochondrial calcium stores in PC12 cells.

  Hanako Hirata, Guiomar S Lopes, Aron Jurkiewicz, Lucia Garcez-do-Carmo, Soraya S Smaili
  [show abstract] [hide abstract]
  ABSTRACT: Endoplasmic reticulum (ER) and mitochondria are intracellular organelles and their interactions are directly involved in different processes such as Ca(2+) signaling in cell survival and death mechanisms. Bcl-2 is an anti-apoptotic protein intrinsically related to ER and mitochondria, modulating Ca(2+) content in these organelles. We investigated the effects of Bcl-2 overexpression on ER and mitochondrial Ca(2+) dynamics in PC12 cells. Bcl-2 overexpressing and control cells were loaded with Fura 2/AM and stimulated with different drugs. Results showed that in Bcl-2 cells, ACh induced a lower Ca(2+) response compared to control. Ca(2+) release induced by TG was decreased in Bcl-2 cells, however, it was greater in Caff induced Ca(2+) rise. In addition, FCCP induced a higher Ca(2+) release in Bcl-2 cells. These results suggest that Bcl-2 overexpression modulate the ER Ca(2+) pools differently and the release of ER Ca(2+) may increase mitochondrial Ca(2+) accumulation. These alterations of intracellular Ca(2+) stores are important mechanisms for the control of Ca(2+) signaling.
  Neurochemical Research 02/2012; 37(2):238-43. · 2.24 Impact Factor
• Article: Mitochondrial involvement in carbachol-induced intracellular Ca2+ mobilization and contraction in rat gastric smooth muscle.

  Roberta M Correa, Simone S L Lafayette, Gustavo J S Pereira, Hanako Hirata, Lúcia Garcez-do-Carmo, Soraya S Smaili
  [show abstract] [hide abstract]
  ABSTRACT: Mitochondria are important modulators of Ca2+ homeostasis. However, it is not clear if they modulate and participate in smooth muscle signaling and contraction. The aim of the present work was to investigate the role of mitochondria in Ca2+ transients and contraction induced by metabotropic muscarinic receptor activation in rat gastric smooth muscle. Carbachol (CCh)-induced contraction was investigated in the absence or presence of increasing concentration of mitochondrial protonophore, carbonyl cyanide p-(trifluoro-methoxy)phenyl-hydrazone (FCCP), in gastric fundus strips. Ca2+ and mitochondrial membrane potential (ΔΨm) measurements were performed in primarily cultured gastric smooth muscle cells loaded with FURA-2 or TMRE dyes. Results show that CCh (1 μM)-induced contraction was inhibited by FCCP in a concentration-dependent manner. In cultured smooth muscle cells CCh (1 μM) caused a cytosolic Ca2+ rise. Preincubation with FCCP strongly inhibited CCh-evoked Ca2+ transients indicating that mitochondria shape intracellular Ca2+ signals. CCh induced elevations of ∆Ψm in 60% of the individual mitochondrion analyzed. Taken together our results indicate that CCh induces release of Ca2+ from intracellular stores, which may be modulated by mitochondria. Thus, mitochondria participate of the intracellular Ca2+ homeostasis in muscarinic contraction in gastric fundus smooth muscle.
  Life sciences 08/2011; 89(21-22):757-64. · 2.56 Impact Factor
• Article: Nicotinic acid adenine dinucleotide phosphate (NAADP) regulates autophagy in cultured astrocytes.

  Gustavo J S Pereira, Hanako Hirata, Gian M Fimia, Lúcia G do Carmo, Claudia Bincoletto, Sang W Han, Roberta S Stilhano, Rodrigo P Ureshino, Duncan Bloor-Young, Grant Churchill, Mauro Piacentini, Sandip Patel, Soraya S Smaili
  [show abstract] [hide abstract]
  ABSTRACT: Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent Ca(2+)-mobilizing messenger that in many cells releases Ca(2+) from the endolysosomal system. Recent studies have shown that NAADP-induced Ca(2+) mobilization is mediated by the two-pore channels (TPCs). Whether NAADP acts as a messenger in astrocytes is unclear, and downstream functional consequences have yet to be defined. Here, we show that intracellular delivery of NAADP evokes Ca(2+) signals from acidic organelles in rat astrocytes and that these signals are potentiated upon overexpression of TPCs. We also show that NAADP increases acidic vesicular organelle formation and levels of the autophagic markers, LC3II and beclin-1. NAADP-mediated increases in LC3II levels were reduced in cells expressing a dominant-negative TPC2 construct. Our data provide evidence that NAADP-evoked Ca(2+) signals mediated by TPCs regulate autophagy.
  Journal of Biological Chemistry 05/2011; 286(32):27875-81. · 4.77 Impact Factor
• Article: Calcium and cell death signaling in neurodegeneration and aging.

  Soraya Smaili, Hanako Hirata, Rodrigo Ureshino, Priscila T Monteforte, Ana P Morales, Mari L Muler, Juliana Terashima, Karen Oseki, Tatiana R Rosenstock, Guiomar S Lopes, Claudia Bincoletto
  [show abstract] [hide abstract]
  ABSTRACT: Transient increase in cytosolic (Cac2+) and mitochondrial Ca2+ (Ca m2+) are essential elements in the control of many physiological processes. However, sustained increases in Ca c2+ and Ca m2+ may contribute to oxidative stress and cell death. Several events are related to the increase in Ca m2+, including regulation and activation of a number of Ca2+ dependent enzymes, such as phospholipases, proteases and nucleases. Mitochondria and endoplasmic reticulum (ER) play pivotal roles in the maintenance of intracellular Ca2+ homeostasis and regulation of cell death. Several lines of evidence have shown that, in the presence of some apoptotic stimuli, the activation of mitochondrial processes may lead to the release of cytochrome c followed by the activation of caspases, nuclear fragmentation and apoptotic cell death. The aim of this review was to show how changes in calcium signaling can be related to the apoptotic cell death induction. Calcium homeostasis was also shown to be an important mechanism involved in neurodegenerative and aging processes.
  Anais da Academia Brasileira de Ciências 10/2009; 81(3):467-75. · 1.09 Impact Factor
• Article: Apoptotic effect of ethanol is potentiated by caffeine-induced calcium release in rat astrocytes.

  Hanako Hirata, Lucas S Machado, Clayton S Okuno, Adriano Brasolin, Guiomar S Lopes, Soraya S Smaili
  [show abstract] [hide abstract]
  ABSTRACT: In this study, we investigated agents that increased intracellular calcium levels and their correlation with apoptotic cell death induction. We used rat astrocytes to investigate the increase in cytosolic Ca2+ (Ca(c)2+) and apoptosis induction by drugs that mobilize Ca2+ from different sources. We observed that thapsigargin (Thap), caffeine (Caff) and FCCP which caused similar increases in Ca(c)2+ levels (30-40%), also induced similar apoptotic rates (30-35%). On the other hand, antimycin (Anti), staurosporine (STS) and ethanol (Eth) promoted higher increases in Ca(c)2+ (55-65 %) and higher apoptotic rates (55-85%). Eth induced cell death in a concentration- and time-dependent manner. After treatment with Eth plus Caff for 6, 12 and 24 h, these effects were strongly potentiated. Results suggest that there might be a correlation between Ca(c)2+ increase and the rate of apoptosis. It is possible that Eth induces cell death by activation of more than one pathway and Ca2+ might be one of the elements involved. The present work indicates that Ca2+ can potentiate death by ethanol in rat astrocytes.
  Neuroscience Letters 02/2006; 393(2-3):136-40. · 2.11 Impact Factor
• Article: Functional properties of agmatine in rat vas deferens

  Neide Hyppolito Jurkiewicz, Lucia Garcez do Carmo, Hanako Hirata, Wilson da Costa Santos, Aron Jurkiewicz
  [show abstract] [hide abstract]
  ABSTRACT: Experiments were performed with rat vas deferens to verify whether agmatine, an endogenous ligand for adrenoceptors and imidazoline receptors, can influence sympathetic neurotransmission, with respect to contractions induced by transmural nerve stimulation, contractions induced by exogenous noradrenaline, and overflow of endogenous noradrenaline. It was shown that agmatine (a) caused a dose-dependent potentiation of electrically induced twitches, up to about 70% in relation to controls, (b) shifted to the right the inhibitory concentration-response curves for clonidine on electrically induced twitches, indicating competitive antagonism at presynaptic α-adrenoceptors, with a pA2 value of 4.12 ± 0.10, (c) shifted to the right the concentration-response curves for noradrenaline-induced contractions, indicating competitive antagonism at postsynaptic α-adrenoceptors as well, with a pA2 value of 4.03 ± 0.10, and (d) caused a dose-dependent increase of KCl-induced overflow of noradrenaline, up to about 90% in relation to controls. It is concluded that agmatine has multiple effects on sympathetic neurotransmission in rat vas deferens.
  European Journal of Pharmacology.
• Article: ω-Conotoxins block neurotransmission in the rat vas deferens by binding to different presynaptic sites on the N-type Ca2+ channel

  Hanako Hirata, Almudena Albillos, Francisco Fernández, José Medrano, Aron Jurkiewicz, Antonio G Garcı́a
  [show abstract] [hide abstract]
  ABSTRACT: Electrically-induced twitch responses of the prostatic segment of vas deferens (0.1 Hz, 65 V, 1 ms) are mainly due to the transient presynaptic release of ATP, which acts postsynaptically on non-adrenergic receptors to contract smooth muscle cells. These responses were fully blocked by nanomolar concentrations of the ω-conotoxins GVIA, MVIIA, and MVIIC, most likely by inhibiting Ca2+ entry through presynaptic N-type Ca2+ channels controlling the release of ATP. Repeated washout of the toxins allowed the recovery of contractions, except for ω-conotoxin GVIA, whose inhibitory effects remained unchanged for at least 60 min. In addition, micromolar concentrations of ω-conotoxin MVIIC were unable to protect against the irreversible inhibition of twitch contractions induced by nanomolar concentrations of ω-conotoxin GVIA. At low extracellular Ca2+ concentrations (1.5 mM), 20 nM of ω-conotoxin GVIA or MVIIA inhibited completely the twitch contractions in about 10 min. In 5 mM Ca2+ the blockade of twitch contractions after 10 min was 70% for both toxins. In 1.5 mM Ca2+ ω-conotoxin MVIIC (1 μM) inhibited completely the twitch contraction after 10 min. In 5 mM Ca2+ blockade developed very slowly and was very poor after 30 min, ω-conotoxin MVIIC depressed the response by only 20%. These results are compatible with the idea that the three ω-conotoxins block the purinergic neurotransmission of the vas deferens by acting on presynaptic N-type voltage-dependent Ca2+ channels. However, ω-conotoxin MVIIC seems to bind to sites different from those recognised by ω-conotoxin GVIA and MVIIA, which are markedly differentiated by their Ca2+ requirements for binding to their receptors.
  European Journal of Pharmacology.