Search PubMed⌕ Search

Biomedical subjects

Osamu Nakagawa

Publications and source records attributed to Osamu Nakagawa.

At least 19 recordsLinked to original sources
PubMed2026

Hox/Meis-dependent gene-regulatory transition underlies cardiopharyngeal neural crest diversification.

Neural crest cells (NCCs) are multipotent migratory cells essential for cardiac development, yet the lineage trajectories and gene regulatory networks underlying their differentiation in the cardiopharyngeal region remain unclear. Here, we integrate single-cell RNA-seq, spatial transcriptomics, and multiomic analyses to construct a comprehensive map of NCC lineages in developing mouse cardiopharyngeal tissues. We identify a transition from Hox-positive pharyngeal NCCs to Hox-negative intracardiac populations associated with the outflow tract cushion, accompanied by a shift in Meis transcription factor binding and gene-regulatory network architecture. By contrast, NCCs forming the aorticopulmonary septum and great vessel smooth muscle retain distinct Hox-codes. A Meis2-Sox9-Scx gene-regulatory network defines a skeletogenic progenitor-like intermediate state that gives rise to coronary artery smooth muscle and semilunar valves. Our findings suggest that the loss of Hox-dependent regional identity enables pharyngeal NCCs to acquire new fates upon entering the cardiac cushion, providing insight into the developmental origins of coronary and valvular calcification.

Journal Article↗
PubMed2006

Hrt and Hes negatively regulate Notch signaling through interactions with RBP-Jkappa.

Notch signaling is central to cell differentiation, organ development, and apoptosis. Upon ligand binding, the Notch intracellular domain (NotchIC) translocates to the nucleus to interact with its DNA-binding partner, RBP-Jkappa. The NotchIC-RBP-Jkappa complex activates target genes, such as those encoding the Hrt and Hes families of basic-helix-loop-helix (bHLH) transcriptional repressors. Hrt transcripts are enriched in the developing cardiovascular system, and mice lacking Hrt2 have cardiac malformations. Here we show that Hrt2 and Hes1 interact with RBP-Jkappa to negatively regulate Notch-dependent activation of Hrt and Hes expression. The bHLH domain of Hrt2 was necessary for this interaction, and disrupting the protein complex abrogated the negative autoregulation. The interaction did not interfere with the formation or DNA-binding of the NotchIC-RBP-Jkappa complex, indicating direct inhibition by Hrt and Hes as co-repressors. These findings suggest a novel mechanism for negative feedback on Notch signaling that requires RBP-Jkappa to interact physically with Hrt and Hes.

Animals↗
PubMed2006

Fluorescence detection of 8-oxoguanosine by G-clamp derivatives.

8-Oxoguanosine, which is derived by the oxidation of guanosine (dG), is known to induce transversion mutations (G:C-->T:A) in DNA. The compounds with small molecular weight for recognizing 8-oxoG were designed on the basis of the structure of the G-clamp, which is reported to have selective affinity toward guanosine. The G-clamp derivatives with the additional binding units toward 8-oxoG were effectively synthesized and named "8-oxoG-clamps". Binding properties were measured by fluorescence quenching of 8-oxoG-clamps. Among the synthesized derivatives, 8-oxoG-clamp with N-benzyloxycarbonyl (Cbz) unit completely discriminated 8-oxoG from other nucleosides by fluorescence quenching.

Carbamates↗
PubMed2005

A WW domain protein TAZ is a critical coactivator for TBX5, a transcription factor implicated in Holt-Oram syndrome.

The T-box transcription factor TBX5 plays essential roles in cardiac and limb development. Various mutations in the TBX5 gene have been identified in patients with Holt-Oram syndrome, which is characterized by congenital defects in the heart and upper extremities. In this study, we identified a WW-domain-containing transcriptional regulator TAZ as a potent TBX5 coactivator. TAZ directly associates with TBX5 and markedly stimulates TBX5-dependent promoters by interacting with the histone acetyltransferases p300 and PCAF. YAP, a TAZ-related protein with conserved functional domains, also stimulates TBX5-dependent transcription, possibly by forming a heterodimer with TAZ. TBX5 lacks a PY motif, which mediates the association of other proteins with TAZ, and interacts with TAZ through multiple domains including its carboxyl-terminal structure. Truncation mutants of TBX5 identified in patients with Holt-Oram syndrome were markedly impaired in their ability to associate with and be stimulated by TAZ. These findings reveal key roles for TAZ and YAP in the control of TBX5-dependent transcription and suggest the involvement of these coactivators in cardiac and limb development.

Abnormalities, Multiple↗
PubMed2005

Transcriptional activity of Pax3 is co-activated by TAZ.

Pax3 is a transcription factor which functions in embryonic development and human diseases. In a yeast two-hybrid screen with full-length Pax3 as bait, we isolated a clone encoding transcriptional co-activator with PDZ-binding motif (TAZ) from an E10.5 mouse embryo cDNA library. Co-immunoprecipitation and nuclear co-localization of TAZ with Pax3 suggest that their association is functionally relevant. In situ hybridization revealed TAZ and Pax3 expression to partially overlap in the paraxial mesoderm, limb buds, and the neural tube. In C2C12 myoblast cells and NIH3T3 cells, TAZ enhanced the transcriptional activity of Pax3 on artificial and microphthalmia-associated transcription factor promoter-luciferase constructs, suggesting that TAZ can function as a co-activator of Pax3. Functional interaction between Pax3 and TAZ may provide a clue to clarifying the mechanism by which Pax3 serves as a transcriptional activator during embryogenesis.

Acyltransferases↗
PubMed2005

Centronuclear myopathy in mice lacking a novel muscle-specific protein kinase transcriptionally regulated by MEF2.

Myocyte enhancer factor 2 (MEF2) plays essential roles in transcriptional control of muscle development. However, signaling pathways acting downstream of MEF2 are largely unknown. Here, we performed a microarray analysis using Mef2c-null mouse embryos and identified a novel MEF2-regulated gene encoding a muscle-specific protein kinase, Srpk3, belonging to the serine arginine protein kinase (SRPK) family, which phosphorylates serine/arginine repeat-containing proteins. The Srpk3 gene is specifically expressed in the heart and skeletal muscle from embryogenesis to adulthood and is controlled by a muscle-specific enhancer directly regulated by MEF2. Srpk3-null mice display a new entity of type 2 fiber-specific myopathy with a marked increase in centrally placed nuclei; while transgenic mice overexpressing Srpk3 in skeletal muscle show severe myofiber degeneration and early lethality. We conclude that normal muscle growth and homeostasis require MEF2-dependent signaling by Srpk3.

Amino Acid Sequence↗
PubMed2005

Promotion of stable triplex formation by partial incorporation of 2',5'-phosphodiester linkages into triplex-forming oligonucleotides.

Pentadecamer homopyrimidine oligonucleotides containing three or more 2',5'-phosphodiester linkages in different modes were prepared and used to evaluate the ability as a triplex-forming oligonucleotide (TFO), and it was found that discontinuous replacement of the 3',5'-phosphodiester linkages in TFO by 2',5'-linkages significantly stabilizes parallel-motif triplexes.

Base Sequence↗
PubMed2005

Presence of 2',5'-linkages in a homopyrimidine DNA oligonucleotide promotes stable triplex formation under physiological conditions.

We prepared 15-mer homopyrimidine oligonucleotides containing three or four 2',5'-linked DNA units, and their ability as a triplex-forming oligonucleotide (TFO) was analyzed in detail UV melting experiments showed that replacement of a 3',5'-linkage by a 2',5'-linkage at every third or fourth residue in TFO significantly promoted stable triplex formation under physiological conditions.

Base Composition↗
PubMed2005

Promotion of acid-mediated cleavage of oligonucleotide P3'->N5' phosphoroamidates by triplex formation: a novel approach to sequence-specific DNA detection.

The 5'-amino-2',4'-BNA, bearing a locked N-type sugar conformation and a P3'-->N5' phosphoramidate linkage, was found to be rapidly cleaved by acid-mediated hydrolysis when they formed a triplex with the target dsDNA. The fluorophore and quencher moieties were introduced into the 5'-amino-2',4'-BNA-modified oligonucleotide which was used as a novel and innovative DNA detection probe.

DNA↗
PubMed2005

BOP, a regulator of right ventricular heart development, is a direct transcriptional target of MEF2C in the developing heart.

The vertebrate heart is assembled during embryogenesis in a modular manner from different populations of precursor cells. The right ventricular chamber and outflow tract are derived primarily from a population of progenitors known as the anterior heart field. These regions of the heart are severely hypoplastic in mutant mice lacking the myocyte enhancer factor 2C (MEF2C) and BOP transcription factors, suggesting that these cardiogenic regulatory factors may act in a common pathway for development of the anterior heart field and its derivatives. We show that Bop expression in the developing heart depends on the direct binding of MEF2C to a MEF2-response element in the Bop promoter that is necessary and sufficient to recapitulate endogenous Bop expression in the anterior heart field and its cardiac derivatives during mouse development. The Bop promoter also directs transcription in the skeletal muscle lineage, but only cardiac expression is dependent on MEF2. These findings identify Bop as an essential downstream effector gene of MEF2C in the developing heart, and reveal a transcriptional cascade involved in development of the anterior heart field and its derivatives.

Animals↗
PubMed2004

Hairy-related transcription factors inhibit GATA-dependent cardiac gene expression through a signal-responsive mechanism.

Combinatorial actions of transcription factors in multiprotein complexes dictate gene expression profiles in cardiac development and disease. The Hairy-related transcription factor (HRT) family of basic helix-loop-helix proteins is composed of transcriptional repressors highly expressed in the cardiovascular system. However, it has remained unclear whether HRT proteins modulate gene expression driven by cardiac transcriptional activators. Here, we have shown that HRT proteins inhibit cardiac gene transcription by interfering with GATA transcription factors that are implicated in cardiac development and hypertrophy. HRT proteins inhibited GATA-dependent transcriptional activation of cardiac gene promoters such as the atrial natriuretic factor (ANF) promoter. Adenovirus-mediated expression of Hrt2 suppressed mRNA expression of ANF and other cardiac-specific genes in cultured cardiomyocytes. Among various signaling molecules implicated in cardiomyocyte growth, constitutively active Akt1/protein kinase B alpha relieved Hrt2-mediated inhibition of GATA-dependent transcription. HRT proteins physically interacted with GATA proteins, and the basic domain of HRT was critical for physical association as well as transcriptional inhibition. These results suggest that HRT proteins may regulate specific sets of cardiac genes by modulating the function of GATA proteins and other cardiac transcriptional activators in a signal-dependent manner.

Animals↗
PubMed2004

Differential cooperation between dHAND and three different E-proteins.

dHAND is a transcription factor belonging to the class B basic helix-loop-helix protein family and is expressed during embryogenesis in the heart, branchial arches, limb buds, and neural crest derivatives. Despite much study, the molecular mechanisms involved in the regulation of dHAND activity are not well understood. We therefore carried out yeast two-hybrid screening using full-length dHAND as bait, which led to identification of several dHAND-binding proteins, including three E-proteins: E2A, ME2, and ALF1. Subsequent analysis revealed that although their heterodimerization and transcriptional activities were similar, dHAND/E-protein heterodimers bind to an E-box element with differing affinities, suggesting they have distinct DNA binding specificities. Moreover, in situ hybridization showed that E-protein genes are expressed fairly ubiquitously among embryonic tissues, including the branchial arches and limb buds. By contrast, little signal was detected in the heart, suggesting that dHAND complexes with partners other than E-proteins in cardiac tissue.

Animals↗
PubMed2004

A rare case of Graves' disease during regular hemodialysis.

We report a case of Graves' disease in a patient on regular hemodialysis. The patient also suffered from Wolff-Parkinson-White (WPW) syndrome and paroxysmal atrial fibrillation, which may both have been manifestations of the Graves' disease because of the increased oxygen demand. To our knowledge, this is the first case to illustrate the usefulness of the antithyroid agent propylthiouracil for Graves' disease complicated by endstage renal disease (ESRD) and WPW syndrome.

Antithyroid Agents↗
PubMed2004

Genotype Gly/Gly of the Arg16Gly polymorphism of the beta2-adrenergic receptor is associated with elevated fasting serum insulin concentrations, but not with acute insulin response to glucose, in type 2 diabetic patients.

The beta(2)-adrenergic receptor (B2AR) is expressed in pancreatic beta-cells and modulates insulin secretion. The purpose of the present study was to evaluate the influence of the Arg16Gly variant allele of B2AR on insulin secretion in patients with type 2 diabetes. We used minimal model analysis of the frequently sampled insulin-modified intravenous glucose tolerance test (FSIGT) and polymerase chain reaction (PCR)-restriction fragment length polymorphism to examine differences of insulin secretion and insulin resistance among three genotypes. There were no significant differences in baseline clinical characteristics, HbA1c, uric acid, CRP or lipid profiles among the three groups. The Gly/Gly group had significantly higher levels of fasting insulin (38.2+/-4.7 pmol/l versus 23.6+/-3.5 pmol/l) and homeostasis model assessment of insulin resistance (HOMA-R) (1.90+/-0.19 versus 1.32+/-0.24), compared with the Arg/Arg group, but there were no significant differences in acute insulin response to glucose (AIRg) bolus, insulin sensitivity (Si), or glucose effectiveness (Sg) among the three genotypes. Several reports have speculated that the Gly16 allele of B2AR exhibits agonist-promoted downregulation, but our findings, elevated fasting insulin concentrations, and previous clinical studies of blood pressure and lypolysis are controversial. The direct mechanism by which the Gly16 allele of B2AR may influence insulin secretion of pancreatic beta-cells is unknown. Further studies of the expression of the allelic receptor in islet cells may help to resolve the role of B2AR in insulin secretion. However, increased sensitivity to catecholamine-induced lipolysis of the Gly allele promotes higher free fatty acids concentrations in the portal system, which could enhance the higher levels of fasting insulin.

Aged↗
PubMed2004

Akt-dependent phosphorylation negatively regulates the transcriptional activity of dHAND by inhibiting the DNA binding activity.

HAND2/dHAND is a basic helix-loop-helix transcription factor expressed in the heart and neural crest derivatives during embryogenesis. Although dHAND is essential for branchial arch, cardiovascular and limb development, its target genes have not been identified. The regulatory mechanisms of dHAND function also remain relatively unknown. Here we report that Akt/PKB, a serine/threonine protein kinase involved in cell survival, growth and differentiation, phosphorylates dHAND and inhibits dHAND-mediated transcription. AU5-dHAND expressed in 293T cells became phosphorylated, possibly at its Akt phosphorylation motif, in the absence of kinase inhibitors, whereas the phosphatidylinositol 3-kinase inhibitor wortmannin and the Akt inhibitor NL-71-101, but not the p70 S6 kinase inhibitor rapamycin, significantly reduced dHAND phosphorylation. Coexpression of HA-Akt augmented dHAND phosphorylation at multiple serine and threonine residues mainly located in the bHLH domain and, as a result, decreased the transcriptional activity of dHAND. Consistently, alanine mutation mimicking the nonphosphorylation state abolished the inhibitory effect of Akt on dHAND, whereas aspartate mutation mimicking the phosphorylation state resulted in a loss of dHAND transcriptional activity. These changes in dHAND transcriptional activity were in parallel with changes in the DNA binding activity rather than in dimerization activity. These results suggest that Akt-mediated signaling may regulate dHAND transcriptional activity through the modulation of its DNA binding activity during embryogenesis.

Amino Acid Sequence↗
PubMed2004

Comparative study between audiovisualsexual stimulation test and nocturnal penile tumescence test using RigiScan Plus in the evaluation of erectile dysfunction.

INTRODUCTION: Although the nocturnal penile tumescence (NPT) test is considered the gold standard for the differential diagnosis of psychogenic versus organic erectile dysfunction (ED), concerns have recently been raised regarding the financial and time expenditure it demands. We evaluated the diagnostic efficacy of the audiovisual sexual stimulation (AVSS) test as an alternative to the NPT test. PATIENTS AND METHODS: A total of 43 patients with ED were examined. Each patient filled in an International Index of Erectile Function (IIEF) questionnaire. The evaluation of each patient consisted of AVSS and NPT tests which were performed using the RigiScan Plus. The results obtained with the two tests were compared. The patients with normal NPT patterns were presumed to have a psychogenic etiology of their ED and those with abnormal NPT patterns to have an organic etiology. RESULTS: The overall IIEF score was 32.5 +/- (SD) 9.2, and the erectile domain score was 12.2 +/- 4.5. Twenty-three patients had normal responses to the AVSS test, while 20 had abnormal responses. Twenty-two of the former 23 patients and 9 of the latter 20 patients had normal NPT patterns. Therefore, the AVSS test discriminated psychogenic ED with 71% sensitivity and 92% specificity. The overall accuracy of the test in this study was 77%. CONCLUSIONS: The AVSS test is simple, practical, and inexpensive, and its diagnostic accuracy is comparable to that of the NPT test. We conclude that the AVSS test should be the examination of choice for the primary etiological diagnosis in ED.

Adult↗