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T Nohno

Publications and source records attributed to T Nohno.

At least 73 records · Page 4Linked to original sources
PubMed1993

Expression patterns of the activin receptor IIA and IIB genes during chick limb development.

Activin is known to induce axial mesoderm during early development in Xenopus embryo. Activin receptor was recently identified to be a member of transmembrane serine/threonine kinase family. We have studied the role of activin-mediated signaling in the limb morphogenesis by identifying the target cells. We isolated cDNAs encoding chicken activin receptors, cARIIA and cARIIB, and examined their expression patterns during chick embryogenesis. The cARIIA gene is expressed in the apical ectoderm of the limb bud at stage 20-21, whereas the cARIIB gene is expressed uniformly in the limb mesenchyme. Expression of the cARIIA gene is confined to dorsal and ventral mesenchyme at stage 23, and later confined to precartilaginous cells. Transcripts of the cARIIA gene are found in developing neuroepithelium of spinal cord, brain and eye, surface ectoderm differentiating to epidermis, and myoblasts differentiating to muscle. The IIB receptor gene is highly expressed in the developing brain. These results suggest that the activins and their receptors are implicated in the limb development, especially, in differentiation of muscle, skin and bone.

Activin Receptors↗
PubMed1993

Studies on phosphorylated transcriptional regulator (NarL) for E. coli nar operon by 31P-NMR spectroscopy.

The sequential transphosphorylation from autophosphorylated nitrate-sensing protein (NarX) to the transcriptional regulator protein (NarL), both operating in signal transduction to control the expression of the respiratory nitrate reductase (nar) operon in E. coli, was demonstrated with an in vitro reconstructed system to function similarly to other bacterial two-component regulatory systems. Over-expression system established by means of the pT7 promoter/polymerase provided both NarX and NarL proteins to reconstruct the in vitro transphosphorylation system. The phosphorylated NarL was detected, and the unstable phosphorylated group was directly assigned to acyl phosphate in the in vitro system by 31P-NMR spectroscopy.

Autoradiography↗
PubMed1992

Expression pattern of the activin receptor type IIA gene during differentiation of chick neural tissues, muscle and skin.

To elucidate target cells of activins during embryogenesis we isolated cDNAs of chick activin receptor type II (cActR-II) and studied expression patterns of the cActR-II gene by in situ hybridization. Transcripts of cActR-II were observed in neuroectoderm developing to spinal cord, brain and eyes, in surface ectoderm differentiating to epidermis, and in myotomes differentiating to muscles. The expression patterns of cActR-II suggest that activin and its receptor are involved in differentiation of chick neural tissues, muscle and skin after inducing the dorsal mesoderm.

Activin Receptors↗
PubMed1992

Differential expression of two msh-related homeobox genes Chox-7 and Chox-8 during chick limb development.

We have isolated two closely related cDNAs, Chox-7 and Chox-8, encoding homeodomain-containing proteins homologous to Drosophila msh. The Chox-7 and Chox-8 genes are chicken cognates of mouse Hox-7.1 and Hox-8.1, respectively. In situ hybridization using 3' regions of the cDNAs as probes revealed that the Chox-7 gene is highly expressed in the mesenchyme subjacent to the apical ectodermal ridge whereas Chox-8 expression is localized in the anterodistal mesenchymal region at early stages of limb formation, suggesting different roles during limb development. At later stages, both genes are expressed in the anterior and posterior mesenchymes and in the interdigital mesenchyme where programmed cell death occurs.

Amino Acid Sequence↗
PubMed1992

Morphogenetic roles of retinoic acid.

We integrated our information on morphogenetic roles of retinoic acid, focusing on development of chick limb. Retinoic acid has been considered to be a putative morphogen released from the ZPA. However, since exogenous retinoic acid induces expression of RAR beta, but not grafted ZPA, the ZPA is unlikely to produce retinoic acid. From the result that retinoic acid-treated cells induce digit duplication, retinoic acid converts anterior cells into ZPA cells. We found that retinoic acid also induces expression of homeobox genes indirectly and that bFGF enhances expression of the homeobox genes. Thus, we considered that retinoic acid and growth factors cooperate with each other to activate homeobox genes. A morphogenetic role of retinoic acid is to coordinate developmental stage of each cells by controlling expression of homeobox genes.

Animals↗
PubMed1991

Involvement of retinoic acid and its receptor beta in differentiation of motoneurons in chick spinal cord.

Retinoic acid is known to play an important role during development of central nervous system. In order to clarify function of retinoic acid during the development, we investigated expression pattern of the chick retinoic acid receptor subtype beta gene by an in situ hybridization method. We found that expression of the beta gene is localized in neural tube at stages 16-20, then is turned to be restricted to developing motoneurons at stages 23-29. These results suggested that retinoic acid and its receptor beta are involved in differentiation of the motoneurons in spinal cord.

Animals↗
PubMed1991

Isoforms of retinoic acid receptor beta expressed in the chicken embryo.

The cDNA sequences of isoforms of retinoic acid receptor beta from the chick have been determined. The sequence is different from that reported previously only in the 5' region, suggesting a product of alternative splicing and differential usage of promoters. One of them, the novel RAR-beta 4 isoform, is presumed to encode an amino-terminal truncated region A of retinoic acid receptor beta.

Amino Acid Sequence↗
PubMed1991

Involvement of the Chox-4 chicken homeobox genes in determination of anteroposterior axial polarity during limb development.

We have isolated and identified four chicken homeobox genes in the upstream region of the Chox-4 complex. The Chox-4g and -4f genes, at the 5' extremity of the complex, were expressed locally in the vicinity of the zone of polarizing activity (ZPA) at early stages of limb development, substantiating the involvement of the genes in anteroposterior axis determination. To confirm their function, we implanted a bead containing retinoic acid, or the ZPA itself, in the anterior margin of the limb bud, leading to formation of mirror-image duplicated digits, and observed the resultant change in gene expression. Expression of the Chox-4g and -4f genes was induced in the new digit-forming region. Those results suggest that positional information assigned by a ZPA morphogen is imprinted on cellular memory by expression of the Chox-4 genes to maintain positional signaling along the anteroposterior axis in the limb field.

Amino Acid Sequence↗
PubMed1991

Retinoic acid induces polarizing activity but is unlikely to be a morphogen in the chick limb bud.

Retinoic acid is a putative morphogen in limb formation in the chick and other vertebrates. In chick limb formation, it is thought that retinoic acid is released from the zone of polarizing activity (ZPA) and the concentration gradient of retinoic acid formed from the posterior to the anterior provides positional cues for digit formation. Implantation of a bead containing retinoic acid at the anterior margin of the limb bud induces a mirror-image symmetrical duplication of the digit pattern similar to that observed when the ZPA is grafted into the anterior margin of the host limb bud. Also, the level of endogenous retinoic acid (25 nM on average) is higher in the posterior one third of the limb bud. We found that when the bead containing either retinoic acid or an analogue but not the ZPA, was implanted in the anterior margin of the chick limb bud, expression of the retinoic acid receptor type-beta gene was induced around the bead within 4 h. These results indicate that exogenous retinoic acid is not identical with the ZPA morphogen. As the anterior tissue exposed to retinoic acid has polarizing activity, we conclude that the primary function of exogenous retinoic acid is to induce polarizing activity in the limb bud.

Amino Acid Sequence↗
PubMed1991

Diurnal regulation of per repeat mRNA in the suprachiasmatic nucleus in rat brain.

'Per repeat is a rodent genomic DNA fragment which is homologous to the Gly-Thr repetitive amino acid sequence of the Drosophila clock gene period'. This study examined the temporal and spatial expression of the per repeat mRNA in rat brain. Northern blot analysis showed that the level of per repeat mRNA species fluctuates under light-dark cycle conditions in rat brain. Furthermore, the fluctuation of per repeat mRNA was clearly observed in the suprachiasmatic nucleus, but not so in other regions including the hippocampus as shown by in situ hybridization. The above results suggest that the Gly-Thr repetitive sequence also plays an important role in the circadian rhythm of mammals.

Animals↗
PubMed1990

Expression of hepatocyte growth factor gene in endothelial and Kupffer cells of damaged rat livers, as revealed by in situ hybridization.

Hepatocyte growth factor (HGF) has been demonstrated to be synthesized and secreted by non-parenchymal liver cells for liver regeneration after hepatic injury. We performed in situ hybridization to identify HGF-producing cell types in rat liver hepatitis induced by administrating carbon tetrachloride as a hepatotoxin. We found that transcripts of the HGF gene are localized in the Kupffer and endothelial cells in normal livers and increased remarkably in the Kupffer cells of the damaged livers. Thus, HGF is concluded to be synthesized in the Kupffer and endothelial cells to repair the liver tissue in paracrine fashion. No significant increase in the transcripts of the HGF gene was observed in livers after partial hepatectomy, indicating that a mechanism on liver regeneration after the hepatectomy differs from that on liver repairs. Since the HGF gene expression was also found in lung and kidney, HGF may be a ubiquitous factor for tissue repairs.

Animals↗
PubMed1990

Expression of retinoic acid receptor genes in neural crest-derived cells during mouse facial development.

Retinoic acid (RA) is known as a teratogen that induces abnormalities in facial structures which are made up mainly of neural crest-derived mesenchyme. We investigated expression patterns of RA receptor (RAR) genes (subtypes alpha, beta, gamma) during mouse facial development. The expression of the RAR beta gene is specific for the mesenchyme around developing eyes and nose, whereas the RAR gamma gene is expressed in the mesenchyme differentiating to facial cartilages and bones. In contrast, the RAR alpha gene is expressed weakly and uniformly over the facial region. These results suggest that crucial roles of endogenous RA in facial development depend on differential functions of the RAR subtypes.

Animals↗
PubMed1990

Expression pattern of acidic and basic fibroblast growth factor genes in adult rat eyes.

Although the retinal angiogenic and mitogenic factors have been identified to be acidic and basic fibroblast growth factors (aFGF and bFGF), little information has so far been available about the cells producing them and their function in retinal tissues. We found, by in situ hybridization, that the expression pattern of the aFGF gene differed remarkably from that of the bFGF gene in adult rat eyes. Our results demonstrated that the aFGF gene was produced by photoreceptor visual cells, neuronal cells in the inner nuclear layer and ganglion cells of the retina, in addition to pigment epithelial cells of the choroid, iris and ciliary body, and epithelial cells of the cornea, conjunctiva and lens, while bFGF was synthesized solely by the photoreceptor visual cells.

Animals↗
PubMed1989

Expression of retinoic acid receptor genes in keratinizing front of skin.

We found, by an in situ hybridization method with riboprobes synthesized from human cDNA of the retinoic acid receptor (RAR), that the RAR genes (predominantly gamma-subtype) are intensively expressed in the epidermis of normal and psoriasic human skins, and also in keratinizing fronts of 4-day-old mouse skins, nail matrices and hair follicles. Thus, target cells of retinoic acid in the skins are concluded to be keratinocytes, which is quite consistent with the fact that retinoic acid regulates keratinization of epidermis in vivo and also modulates expression of the keratin gene in vitro.

Animals↗
PubMed1989

Spatial and temporal expression pattern of retinoic acid receptor genes during mouse bone development.

Spatial and temporal expression pattern of retinoic acid receptor (RAR) genes was investigated in mouse finger bones during development by an in situ hybridization method with riboprobes synthesized from a human cDNA of the RAR-alpha. We found that the RAR genes are expressed intensively and specifically in calcifying fronts of the mouse finger bones, whereas the expression pattern is rather uniform in the limb buds and cartilage matrices of the embryonic fingers. Our findings are consistent with the fact that vitamin A is essential for normal mammalian bone development.

Animals↗
PubMed1989

The narK gene product participates in nitrate transport induced in Escherichia coli nitrate-respiring cells.

The nucleotide sequence of the Escherichia coli narK gene, which is located in the upstream region of the narCHJI operon, was determined. The narK gene encodes a very hydrophobic protein with 463 amino acid residues (Mr 49,693). A narK deletion mutant, under conditions for the induction of nitrate respiration, was unable to perform nitrate transport. Loss of transport activity was recovered by transforming the mutant with a narK+ plasmid. Thus, we conclude that the narK gene encodes a transmembrane protein participating in nitrate transport. In the narK promoter region, we defined a unique sequence that we designate as a 'nitrate box', functioning as a putative NarL-binding site, in addition to the consensus sequence of the 'anaero-box'.

Amino Acid Sequence↗
PubMed1989

The narX and narL genes encoding the nitrate-sensing regulators of Escherichia coli are homologous to a family of prokaryotic two-component regulatory genes.

The nucleotide sequence of a 4.4-kilobase SacII-SspI fragment encoding the narXL operon and a part of the narK gene of Escherichia coli has been determined. The narX and narL genes encode proteins of molecular weight 67,275 and 23,927, respectively, and are transcribed from a common promoter, narXp, locating within 429 bases upstream of narX. Transcription from narXp is not significantly induced by nitrate under anaerobiosis, whereas transcription from narK promoter, which overlaps narXp region and is transcribed divergently, is fully induced by nitrate. The N-terminal two-thirds of the NarL protein has extensive homology with those of a diverse set of prokaryotic regulatory proteins, including OmpR, PhoB, SfrA, UhpA, CheY, CheB, NtrC, DctD, FixJ, VirG, SpoOF, and SpoOA. A segment locating in the C-terminal half of the NarL protein seems to have potential most likely to form the helix-turn-helix structure characteristic of a class of DNA-binding protein. The protein is considered to play a role as a transcriptional activator of the nitrate reductase operon, narCHJI, and the narK gene. The C-terminal region of the NarX protein also has homology with other regulatory proteins known as counterparts of two-component regulatory systems, such as EnvZ, PhoR, PhoM, CpxA, NtrB, DctB, FixL, and VirA. Presence of two copies of hydrophobic segments in the N-terminal half of the NarX protein suggests the role as a transmembrane receptor sensing nitrate.

Amino Acid Sequence↗