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T Momoi

Publications and source records attributed to T Momoi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Six4, a putative myogenin gene regulator, is not essential for mouse embryonal development.

Six4 is a member of the Six family genes, homologues of Drosophila melanogaster sine oculis. The gene is thought to be involved in neurogenesis, myogenesis, and development of other organs, based on its specific expression in certain neuronal cells of the developing embryo and in adult skeletal muscles. To elucidate the biological roles of Six4, we generated Six4-deficient mice by replacing the Six homologous region and homeobox by the beta-galactosidase gene. 5-Bromo-4-chloro-3-indolyl-beta-D-galactopyranoside staining of the heterozygous mutant embryos revealed expression of Six4 in cranial and dorsal root ganglia, somites, otic and nasal placodes, branchial arches, Rathke's pouch, apical ectodermal ridges of limb buds, and mesonephros. The expression pattern was similar to that of Six1 except at the early stage of embryonic day 8.5. Six4-deficient mice were born according to the Mendelian rule with normal gross appearance and were fertile. No hearing defects were detected. Six4-deficient embryos showed no morphological abnormalities, and the expression patterns of several molecular markers, e.g., myogenin and NeuroD3 (neurogenin1), were normal. Our results indicate that Six4 is not essential for mouse embryogenesis and suggest that other members of the Six family seem to compensate for the loss of Six4.

Animals↗
PubMed2000

Caspases that are activated during generation of nuclear polyglutamine aggregates are necessary for DNA fragmentation but not sufficient for cell death.

Truncated polypeptides containing expanded polyglutamine (polyQ) stretches tend to form cytoplasmic or nuclear aggregates in cultured cells, leading to cell death. Although it has been shown recently that caspase-8 coaggregates with polyQ and is activated during polyQ-mediated cell death, little is known of the location and timing of caspase-8 activation by nuclear polyQ aggregates. Also, the relationship between nuclear polyQ aggregate-mediated cell death and activation of other caspases is unclear. In P19 embryonal carcinoma (EC) cells, which can be made to differentiate into neuronal cells, polyQ72 repeats preferentially aggregate in the nucleus. Nuclear aggregates of polyQ72 induced P19 EC cell death, with a high frequency of cells exhibiting morphology characteristic of apoptosis (i.e., roundness, cell shrinkage, chromatin condensation) and DNA fragmentation. In the present study, we used antisera that specifically recognized the active forms of caspase-8, -3, and -9 but not their proforms, and showed that only caspase-8 and -3 were activated during the generation of polyQ72 aggregates in P19 EC cell nuclei. Furthermore, we showed that the caspase inhibitor z-VAD-fmk inhibited DNA fragmentation, but only partially inhibited the appearance of apoptotic morphology. Thus, caspase activation, including caspase-8 and -3, is necessary for polyQ-mediated DNA fragmentation but not sufficient for polyQ-mediated cell death in P19 EC cells.

Apoptosis↗
PubMed2000

Detection of caspase-9 activation in the cell death of the Bcl-x-deficient mouse embryo nervous system by cleavage sites-directed antisera.

Caspases, which play crucial roles during apoptosis, are activated from their inactive proforms in a sequential cascade of cleavage by other members of the caspase family. Caspase-9 is autoprocessed by the Apaf-1/cytochrome c pathway and acts at an early point in this cascade, whereas Bcl-xL, an antiapoptotic member of the Bcl-2 family, prevents activation of caspases in vitro. Little is known, however, about the relation between caspase-9 and Bcl-xL during development of the mammalian nervous system. We used antisera against two cleavage sites in mouse caspase-9 that recognize only the activated form of mouse caspase-9, and we examined immunohistochemically the activation of mouse caspase-9 in the nervous system of Bcl-x-deficient mouse embryos. Mouse caspase-9 is processed at both D(353) and D(368), but it is processed preferentially at D(368) during apoptosis of cultured cells induced by various stimuli and in the nervous system of Bcl-x-deficient mouse embryos. We show that Bcl-xL protects against caspase-9- and/or caspase-3-dependent apoptosis in the caudal portion of the ventral hindbrain, anterior horn cells, and dorsal root ganglia neurons of the normal mouse embryos and against caspase-9/caspase-3-independent apoptosis in the dorsal region of the nervous system including the dorsal spinal cord. Furthermore, we demonstrate that Bcl-xL blocks cytochrome c release from mitochondria, causing activation of caspase-9 in anterior horn cells and dorsal root ganglia neurons in mouse embryos at embryonic day 11.5.

Animals↗
PubMed2000

In situ detection of activated caspase-3 in apoptotic granule neurons in the developing cerebellum in slice cultures and in vivo.

Some granule neurons naturally undergo apoptosis in the external granular layer (EGL) of the postnatally developing cerebellum. In the present study, we examined the involvement of caspase-3 in this apoptosis using an organotypic slice culture system of postnatal rat cerebellum and an antibody specific for the active form of caspase-3 (p20/17). Double staining by immunohistochemistry against p20/17 and in situ nick-end labeling showed that p20/17 was present in some of the apoptotic EGL neurons. A similar staining pattern was also observed in the postnatal cerebellum in vivo. Double positive cells were observed more frequently when T7 DNA polymerase was used for the DNA fragmentation labeling in place of terminal deoxynucleotidyl transferase, by which apoptotic cells at earlier stages were thought to be labeled. Taken together, whereas caspase-3 was shown to be activated in some of the apoptotic EGL neurons in the developing cerebellum, activation of caspase-3 in some apoptotic EGL neurons may occur before they become positive on DNA fragmentation labeling. In addition, there may be another mechanism of EGL neuron apoptosis that is independent of caspase-3.

Animals↗
PubMed2000

Localization of active form of caspase-8 in mouse L929 cells induced by TNF treatment and polyglutamine aggregates.

The relation between activation of caspase-8 and polyglutamine aggregates has been focused. We prepared an antiserum (anti-m8D387) that recognizes the active form but not the proform of mouse caspase-8. We used immunostaining with anti-m8D387 antiserum to compare the localizations of activated mcaspase-8 in L929 (clone 1422) cells induced by TNF and polyglutamine aggregates. Anti-m8D387 was positive throughout cytoplasm of the TUNEL-positive cells induced by TNF treatment, whereas the anti-m8D387 reactivity was not positive throughout cytoplasm of the cells expressing polyglutamine but was restricted to polyglutamine aggregates. In contrast with TNF-treated cells, cells expressing anti-m8D387-positive cytoplasmic polyglutamine aggregates did not undergo TUNEL-positive apoptosis. Thus activated caspase-8 associated with polyglutamine aggregates alone was not sufficient to induce TUNEL-positive apoptosis of L929 (clone 1422) cells. The distribution of activated caspase-8 associated with polyglutamine aggregates may be essential for the polyglutamine-mediated cell death or downstream of caspase-8 may be different in the TNF-treated cells and cells expressing polyglutamine.

Animals↗
PubMed2000

Targeted expression of baculovirus p35 caspase inhibitor in oligodendrocytes protects mice against autoimmune-mediated demyelination.

The mechanisms underlying oligodendrocyte (OLG) loss and the precise roles played by OLG death in human demyelinating diseases such as multiple sclerosis (MS), and in the rodent model of MS, experimental autoimmune encephalomyelitis (EAE), remain to be elucidated. To clarify the involvement of OLG death in EAE, we have generated transgenic mice that express the baculovirus anti-apoptotic protein p35 in OLGs through the Cre-loxP system. OLGs from cre/p35 transgenic mice were resistant to tumor necrosis factor-alpha-, anti-Fas antibody- and interferon-gamma-induced cell death. cre/p35 transgenic mice were resistant to EAE induction by immunization with the myelin oligodendrocyte glycoprotein. The numbers of infiltrating T cells and macrophages/microglia in the EAE lesions were significantly reduced, as were the numbers of apoptotic OLGs expressing the activated form of caspase-3. Thus, inhibition of apoptosis in OLGs by p35 expression alleviated the severity of the neurological manifestations observed in autoimmune demyelinating diseases.

Animals↗
PubMed2000

Efficacy of long-term azathioprine for relapsing nephrotic syndrome.

Seven patients who had an initial attack of nephrotic syndrome in childhood and had frequent relapses even after cyclophosphamide therapy were given a 2-year course of azathioprine. The mean annual relapse rates decreased from 2.4+/-0.5 in the year preceding azathioprine to 0.4+/-0.8 in the 1st and 2nd years after its initiation. All six patients who were observed for more than 6 months after discontinuation of the therapy were relapse free for this period. Average doses of prednisolone could also be decreased in the 2nd and subsequent years after the therapy. There were no significant toxic effects. Long-term azathioprine therapy may be well tolerated and effective for nephrotic patients with frequent relapses.

Adolescent↗
PubMed2000

Deficiency in caspase-9 or caspase-3 induces compensatory caspase activation.

Dysregulation of apoptosis contributes to the pathogenesis of many human diseases. As effectors of the apoptotic machinery, caspases are considered potential therapeutic targets. Using an established in vivo model of Fas-mediated apoptosis, we demonstrate here that elimination of certain caspases was compensated in vivo by the activation of other caspases. Hepatocyte apoptosis and mouse death induced by the Fas agonistic antibody Jo2 required proapoptotic Bcl-2 family member Bid and used a Bid-mediated mitochondrial pathway of caspase activation; deficiency in caspases essential for this pathway, caspase-9 or caspase-3, unexpectedly resulted in rapid activation of alternate caspases after injection of Jo2, and therefore failed to protect mice against Jo2 toxicity. Moreover, both ultraviolet and gamma irradiation, two established inducers of the mitochondrial caspase-activation pathway, also elicited compensatory activation of caspases in cultured caspase-3(-/-) hepatocytes, indicating that the compensatory caspase activation was mediated through the mitochondria. Our findings provide direct experimental evidence for compensatory pathways of caspase activation. This issue should therefore be considered in developing caspase inhibitors for therapeutic applications.

Animals↗
PubMed2000

Clinicopathologic study of mass-screened neuroblastoma with special emphasis on untreated observed cases: a possible histologic clue to tumor regression.

Spontaneous regression and maturation of neuroblastoma (NB) are well documented and occur frequently in infants, including those detected by mass screening. To seek histologic clues for regression/maturation in mass-screened NB, clinicopathologic features of 12 tumors that were resected after 2 to 18 months of untreated observation were reviewed. Unobserved screened and age-matched unscreened patients were also studied. To evaluate the possible important role of apoptosis, apoptotic cells were detected by in situ deoxyribonucleic acid (DNA) nick end labeling and immunohistochemical stain for activated caspase-3. Nests with a varying degree of reduced cellularity ("less cellular" and "hypocellular" nests) were common in patients younger than 18 months of age, and were rare in older patients. Two characteristic cells, which have not been focused previously, were frequent, especially in the hypocellular nests. One showed amorphic eosinophilic cytoplasm with pyknotic nuclei and the other contained plump cytoplasm with well-maintained nuclei. These cells were also observed in 89% of the unobserved screened NBs and 79% of the age-matched unscreened patients with good outcome, whereas they could not be confirmed in any of the age-matched unscreened NBs with poor outcome. The amorphic and plump cells were negative for activated caspase-3 and in situ DNA nick end labeling. From these results, the authors hypothesize that these cells most likely represent a degenerative process, in either a state before the activation of caspase-3 or a caspase-independent form of cell death. The presence of less cellular and hypocellular nests with amorphic/plump cells may serve as one of the important clues in predicting tumor prognosis.

Age Factors↗
PubMed2000

A novel congenital myopathy with apoptotic changes.

We report on a female child with congenital myopathy with delayed developmental milestones and mental retardation. The most striking pathological finding was the presence of many condensed to fragmented myonuclei. DNA fragmentation was confirmed by the TUNEL method and supported by the ultrastructural characteristics of apoptotic nuclear changes. We also demonstrated immunohistochemically the activation of caspase-3 and caspase-9. This appears to be the first reported case of congenital myopathy with apoptotic process.

Apoptosis↗
PubMed1999

Akt phosphorylation site found in human caspase-9 is absent in mouse caspase-9.

Caspase-9 is one caspase upstream of caspase-3 and its activation is stimulated by Apaf-1/cytochrome c and inhibited by Akt signals. BAD phosphorylation by Akt is an essential step for growth factor-mediated inhibition of caspase activation. Recently, it was shown that human caspase-9 is phosphorylated by Akt and that its protease activity is reduced. To clarify the molecular mechanism of regulation of caspase-9 activation in neuronal apoptosis, we isolated two alternative splicing products of mouse caspase-9, caspase-9L and caspase-9S, from a P19 embryonal carcinoma cell cDNA library. Curiously, the Akt phosphorylation sites and motifs found in human caspase-9 were absent in both mouse caspase-9L and -9S. Mouse caspase-9 was not phosphorylated by activated Akt in vitro. Reverse transcription polymerase chain reaction analysis showed that the absent Akt motif is not limited to caspase-9 expressed in P19 embryonal carcinoma cells but also occurs in caspase-9 expressed in mouse, rat, and monkey. These results suggest that inhibition of caspase-9 activation by Akt-dependent phosphorylation is not generalized across species.

Amino Acid Sequence↗
PubMed1999

Activation of neuronal caspase-3 by intracellular accumulation of wild-type Alzheimer amyloid precursor protein.

Forced overexpression of wild-type Alzheimer amyloid precursor protein (APP) causes postmitotic neurons to degenerate. Caspase-3 (CPP32) is a principal cell death protease involved in neuronal apoptosis during physiological development and under pathological conditions. Here, we investigated whether APP overexpression activates caspase-3 in human postmitotic neurons using adenovirus-mediated gene transfer. When a recombinant adenovirus vector expressing human wild-type APP695 was infected in vitro into neurally differentiated embryonal carcinoma NT2 cells, only postmitotic neurons underwent severe degeneration. Before neurodegeneration, full-length APP- and Abeta-immunoreactive peptides were accumulated in infected neurons, and caspase-3-like protease activity was markedly elevated. Western blot analysis revealed that activated caspase-3 subunits were generated in APP-accumulating neurons. Such neuronal caspase-3 activation was undetectable in NT2 neurons infected with beta-galactosidase-expressing adenovirus. Addition of the caspase-3 inhibitor acetyl-Asp-Glu-Val-Asp-aldehyde to the culture medium significantly reduced the severity of degeneration exhibited by APP-overexpressing neurons. Immunocytochemical analyses revealed that some APP-accumulating neurons contained activated caspase-3 subunits and exhibited the characteristics of apoptosis, such as chromatin condensation and DNA fragmentation. Activation of caspase-3 was also observed in vivo in rat hippocampal neurons infected with the APP-expressing adenovirus. These results suggest that wild-type APP is an intrinsic activator of caspase-3-mediated death machinery in postmitotic neurons.

Adenoviridae↗
PubMed1999

Bcl-xL is a negative regulator of caspase-3 activation in immature neurons during development.

Caspases and Bcl-xL, the mammalian homologues of the Caenorhabditis elegans (C. elegans) ced-3 and ced-9 genes, respectively, regulate apoptosis of various cells. Caspase-3 is processed into an active form (p20 or p17 and p12) during apoptosis. We investigated the relation between caspase-3 and Bcl-xL during development by examining activation of caspase-3 and apoptotic cells in Bcl-x-deficient (bcl-x(-/-)) mice at embryonic (E) day 11.5. We used a double-staining technique with a cleavage site-directed antibody against caspase-3 (anti-p20/17) and terminal-deoxytransferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL). Bcl-xL-deficiency increased both numbers of p20/17-positive and -negative apoptotic cells in dorsal root ganglia (DRG); the numbers of p20/17-positive apoptotic cells in the caudal parts of the ventral hindbrain and ventral spinal cord; and the numbers of p20/17-negative apoptotic cells in the dorsal midbrain, dorsal hindbrain, and dorsal spinal cord. Thus, Bcl-xL blocks the caspase-3-dependent apoptotic pathway in the restricted regions of the nervous system during development. Furthermore, these observations suggest that Bcl-xL protects against activation of the caspase-3-independent apoptotic pathway. Other caspases or apoptotic mechanisms may also be activated in the nervous systems of bcl-x(-/-) mice.

Animals↗
PubMed1999

Differential effects of Bcl-2 overexpression on hippocampal CA1 neurons and dentate granule cells following hypoxic ischemia in adult mice.

In contrast to its known anti-apoptotic activity in sympathetic neurons, immortal neuronal cell lines, and primary cultured immature neurons of the central nervous system (CNS), the role of Bcl-2 in CNS neurons in the adult brain is poorly understood. In the present study, we examined effects of overexpression of Bcl-2 on selective neuronal death of the hippocampal CA1 neurons and the dentate granule cells induced by hypoxic ischemia in adult transgenic mice overexpressing human Bcl-2 under the control of neuron-specific enolase (NSE-hbcl-2). At the light microscopic level, numbers of TUNEL-positive cells with pyknotic nuclei were observed in the CA1 subfield of NSE-hbcl-2 transgenic mice, as well as that of wild-type mice, after hypoxic ischemic insult, although the onset of neuronal death was apparently delayed in NSE-hbcl-2 transgenic mice. The electron microscopic studies showed that morphological changes of the degenerating CA1 neurons from both groups were clearly distinct from ordinary apoptosis. In contrast, a significant amount of degenerating dentate granule cells from wild-type but not from transgenic mice had typical apoptotic nuclei by the treatment. The activation of caspase-3 was detected in the dentate granule cells but not that of the CA1 neurons. These results indicate that the overexpression of Bcl-2 effectively suppressed dentate granule cell apoptosis but only delayed cell death of the CA1 neurons induced by hypoxic ischemia, suggesting the occurrence of a non-apoptotic, caspase-3-independent mechanism for neuronal death in the CA1 subfield.

Animals↗
PubMed1999

Activation of caspase-3 apoptotic pathways in skeletal muscle fibers in laminin alpha2-deficient mice.

dy/dy mice, which carry an unidentified mutation in the Lama2 gene, show dystrophic pathologies similar to those of human congenital muscular dystrophy. Laminin alpha2 deficiency induces apoptosis with DNA fragmentation. Caspases, which are involved in various types of cell death, are sequentially activated through a processing by other members of caspases. By using a cleavage site-directed antibody against caspase-3 that specifically reacts with the active form of caspase-3, we immunochemically demonstrated that caspase-3 is activated in the skeletal muscle fiber of dy/dy mice and that some of the activated caspase-3 muscle fibers are TUNEL-positive. Thus the lack of laminin alpha2 signals activates caspase-3, resulting in the apoptosis of muscle fibers.

Animals↗
PubMed1999

Relatively longer hand in patients with Ullrich-Turner syndrome.

We analyzed the total hand length (HL) and length of noncarpal bones (NCL) in 50 Japanese patients with Ullrich-Turner syndrome (UTS) and in 443 other patients with short stature used as controls. In each patient group we calculated relative HL (RHL= HL/height) and relative NCL (RNCL= NCL/height). UTS patients had significantly greater RHL than controls. The greater RHL in UTS patients is mainly due to their longer, short tubular bones. The RHL is not affected by ages and karyotypes of UTS patients or growth hormone treatments given to them. We conclude that relatively longer hands are a common manifestation of UTS and that this parameter is useful for the diagnosis of the syndrome among short females, who usually need chromosome analysis.

Adolescent↗
PubMed1999

Apoptosis in favourable neuroblastomas is not dependent on Fas (CD95/APO-1) expression but on activated caspase 3 (CPP32).

The mechanisms of apoptosis in neuroblastomas have been investigated by examining the expression profiles of Fas, Fas ligand (FasL), and caspase 3 in 42 primary tumour tissues. Immunohistochemically, no or weak Fas expression was detected in 25 out of 29 neuroblastomas (86 per cent), whereas high levels of expression of FasL and pro-caspase 3 were noted in 30 and 29 of 42 tumours, respectively (approximately 70 per cent). Overexpression of pro-caspase 3, but not FasL, correlated significantly with a younger age and low tumour stage. Western blot analysis of ten neuroblastomas confirmed the lack of Fas expression and the presence of strong FasL expression in all samples and pro-caspase 3 expression in five tumours, of which four belonged to the favourable type. These favourable tumours also showed vigorous Asp-Glu-Val-Asp (DEVD) hydrolytic, or caspase 3-like activities, while the unfavourable tumour lacked such activity. Moreover, immunostaining for the p17 subunit of the caspase 3 heterodimer showed that active caspase 3 was mainly localized in apoptotic tumour cells. Combined together, our results suggest that caspase 3, activated via a Fas-independent pathway, may play important roles in apoptosis, suppression of growth, and, in some cases, regression of favourable neuroblastomas.

Apoptosis↗