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Takeshi Satoh

Publications and source records attributed to Takeshi Satoh.

8 recordsLinked to original sources
PubMed2006

Characterization of a novel low-molecular-mass dual specificity phosphatase-4 (LDP-4) expressed in brain.

Dual-specificity phosphatases (DSPs), which dephosphorylate proteins at Ser/Thr as well as Tyr residues, are thought to be involved in critical signaling events such as control of MAP kinases (MAPKs). We have isolated the cDNA for a novel DSP and termed it low molecular mass DSP-4 (LDP-4). LDP-4 is composed of 211 amino acids with a predicted molecular mass of 23.9-kDa. Northern blot analysis using various mouse tissues showed that the LDP-4 transcript was expressed exclusively in brain. In situ hybridization showed that brain expression of LDP-4 was ubiquitous except for the hippocampus. When expressed in COS-7 cells, FLAG-tagged LDP-4 protein was present within the nucleus and Golgi apparatus. LDP-4 expression did not reduce phosphorylation levels of MAPKs, but rather evoked activation of JNK and p38.

Amino Acid Sequence↗
PubMed2006

[Persistent left ventricular systolic dysfunction in a patient with ampulla cardiomyopathy: a case report].

An 81-year-old woman was admitted for treatment of diastolic heart failure. Two weeks after admission, she suffered sudden chest pain without somatic and/or psychological stress. Electrocardiography showed ST elevation in leads V2- V5. Coronary angiography did not reveal any significant stenosis in the epicardial coronary artery. Left ventriculography showed apical akinesis with basal and mid hyperkinesis. The diagnosis was ampulla cardiomyopathy. The abnormality on electrocardiography was normalized 2 months later, but apical akinesis persisted for 1 year. Myocardial contrast echocardiography showed microvascular dysfunction consistent with the apical akinesis for 1 year. Microvascular dysfunction may be important in the pathophysiological state of ampulla cardiomyopathy.

Aged, 80 and over↗
PubMed2004

Characterization of a novel low-molecular-mass dual-specificity phosphatase-3 (LDP-3) that enhances activation of JNK and p38.

We have isolated a mouse cDNA for a novel dual-specificity phosphatase designated LDP-3 (low-molecular-mass dual-specificity phosphatase 3). The 450 bp open reading frame encodes a protein of 150 amino acids with a predicted molecular mass of 16 kDa. Northern blot and reverse transcription-PCR analyses show that LDP-3 transcripts are expressed in almost all mouse tissues examined. In vitro analyses using several substrates and inhibitors indicate that LDP-3 possesses intrinsic dual-specificity phosphatase activity. When expressed in mammalian cells, LDP-3 protein is localized mainly to the apical submembrane area. Forced expression of LDP-3 does not alter activation of ERK (extracellular-signal-regulated kinase), but rather enhances activation of JNK (c-Jun N-terminal kinase) and p38 and their respective upstream kinases MKK4 (mitogen-activated protein kinase kinase 4) and MKK6 in cells treated with 0.4 M sorbitol. By screening with a variety of stimuli, we found that LDP-3 specifically enhances the osmotic stress-induced activation of JNK and p38.

Amino Acid Sequence↗
PubMed2003

Conversion of semantic information into phonological representation: a function in left posterior basal temporal area.

A unique feature of Japanese language is that its written sentences consist of both morphograms (kanji) and syllabograms (kana). Despite extensive research by PET, functional MRI and magnetoencephalography, the issues of the difference (or the similarities) between the processing of kanji and kana, and between word reading and object/picture naming have not been resolved as yet. This study investigated the function of the posterior basal temporal area in the language dominant hemisphere in auditory and visual language processing, with special emphasis on semantic and phonological recognition. Subdural electrode grids were placed on the left temporal area of a right-handed woman with intractable temporal lobe epilepsy as part of a pre-surgical evaluation. Her dominant hemisphere for language was shown to be the left on the Wada test. Electric stimulation of 50 Hz was applied to the electrodes during the tasks related to language. Our results showed a clear distinction in the responses and/or performance of the subject depending on the type of characters presented and the tasks employed. Electric stimulation of a localized area in the posterior basal temporal lobe caused neither comprehensive nor productive deficit in the tasks using auditory stimuli. In the tasks using visual stimuli, in contrast, impairments were observed in (i) reading of kanji words and (ii) naming of objects/pictures and geometric designs, but not in (iii) reading of kana, (iv) copying of kanji, kana and geometric designs, and (v) using tools. The subject maintained full comprehension of spoken language, suggesting that the auditory tasks are not processed in the posterior basal temporal area. The fact that the impairment of kanji reading and disturbance of object/picture naming were elicited by electric stimulation of the same area indicates that there is at least one anatomical area that is used commonly for kanji (but not kana) and object processing. The conceptual entity of the test items supposedly was recognized correctly, but the concept failed to be matched to correct phonological representation. The left posterior basal temporal area, therefore, has an important function of connecting visual semantic information into phonological representation.

Adult↗
PubMed2002

Accumulation of cytoplasmic lipid droplets in bovine embryos and cryotolerance of embryos developed in different culture systems using serum-free or serum-containing media.

In this study, the quantitative fluctuation of cytoplasmic lipid droplets (LD) and cryotolerance were investigated in bovine embryos derived from in vitro-matured (IVM) and in vitro-fertilized (IVF) oocytes developed in different culture systems using serum-free or serum-containing media. The serum-free cultures were grown using IVMD101 medium in conjunction with bovine cumulus/granulosa cell (BCGC) cocultures or IVD101 medium without BCGC cocultures, and the serum-containing cultures were grown in the presence of BCGC cocultures using HPM199 medium supplemented with 5% calf serum (HPM199 + CS). Large numbers of sudanophilic LD were present in the cytoplasm of bovine embryos from 2-cell to hatched blastocyst stages, and the number and size differed between the embryos cultured in serum-free and serum-supplemented media. In the embryos cultured in HPM199 + CS, large (2-6 microm in diameter) sudanophilic LD increased significantly from the morula to the blastocyst stages. Throughout the embryonic development, the embryos developed in serum-free cultures with and without BCGC cocultures had numerous sudanophilic LD, but most of these droplets were small (<2 microm in diameter) and large LD were less numerous than those embryos cultured in HPM199 + CS. Giant LD (>6 microm in diameter) were frequently observed in morulae and blastocysts (including early blastocysts) developed in HPM199 + CS. Electron microscopic observations demonstrated that large LD were abundant in the cytoplasm of trophoblast and embryonic (inner cell mass) cells of blastocysts cultured in HPM199 + CS. These large LD were identified as osmophilic LD, an indication that these lipid inclusions contained a significant proportion of unsaturated lipids. Many elongated mitochondria were found in embryos developed in IVMD101 and IVD101 at the morula and early blastocyst stages, whereas many of the mitochondria in the morulae developed in HPM199 + CS were of an immature form such as spherical or ovoid shape. The survival and hatching rates of embryos (morulae, early blastocysts, and blastocysts) produced in serum-free media (both IVMD101 and IVD101) after post-thaw culture were superior to those of embryos produced in serum-containing medium. These results showed that bovine embryos cultured in serum-containing medium abnormally accumulated cytoplasmic lipids into their cytoplasm and the excess accumulation of cytoplasmic LD in embryos may affect the cryotolerance of embryos.

Animals↗
PubMed2002

A novel low-molecular-mass dual-specificity phosphatase, LDP-2, with a naturally occurring substitution that affects substrate specificity.

We have identified a novel dual-specificity phosphatase (DSP), called LDP-2 (low-molecular-mass DSP-2), composed of 220 amino acid residues showing high sequence homology to VHR and LDP-1/TMDP, which belong to a family of DSPs with low molecular masses. The LDP-2 gene is ubiquitously expressed, and LDP-2 is localized in the cytoplasm. The main structural feature of LDP-2 is that the serine-156 residue located in the common active site sequence motif, HCXXGXXRS, for DSP is naturally substituted with an alanine residue. The recombinant LDP-2 protein showed extremely low phosphatase activity towards p-nitrophenyl phosphate (pNPP). Back-mutation of Ala-156 in LDP-2 to a serine (A156S mutation) conferred significant phosphatase activity towards pNPP. However, both LDP-2 and LDP-2 (A156S) exhibited substantial phosphatase activities towards both phospho-seryl/threonyl and -tyrosyl residues of myelin basic protein, with similar specific activities. Ala-156 of LDP-2 might be crucially involved in the recognition of a physiological substrate. We analyzed the effect of VHR and LDP-2 on mitogen-activated protein kinases (MAPKs) in vivo. We first found that VHR inhibits the activation of p38 as well as ERK and JNK, with similar efficiency. Under the conditions used, LDP-2 specifically suppressed JNK activation.

Amino Acid Sequence↗