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Biomedical subjects

Yasuo Kitajima

Publications and source records attributed to Yasuo Kitajima.

At least 19 recordsLinked to original sources
PubMed2006

Mice transgenic for Kit(V620A): recapitulation of piebaldism but not progressive depigmentation seen in humans with this mutation.

Piebaldism is an autosomal dominant genetic pigmentary disorder, characterized by congenital white hair and patches located on the forehead, anterior trunk, and extremities. Most piebald patients have a mutation of the KIT gene, which encodes a tyrosine kinase receptor involved in pigment cell development. The white hair and patches of such patients are already completely formed at birth and do not usually expand thereafter. This stability of pigmented spots also applies to Kit(W) and Kitl(Sl) mutant mice. However, two novel cases of piebaldism were reported in 2001, in which both mother and daughter having a novel Val620Ala mutation in their KIT gene showed progressive depigmentation. To prepare an animal model of this mutation, to explore undefined functions of KIT signaling for maintaining pigmented melanocytes in the skin or more specifically the integrity of the melanocyte stem cell system in the postnatal skin, we produced transgenic mice expressing Val620Ala Kit. These mice well mimicked the white spotting pattern of patients; however, no change in this pattern was observed after birth, even after increasing the transgene expression by various means. Here, we report the unexpectedly extremely stable maintenance of the melanocyte stem cell system under stringent conditions for KIT signaling.

Animals↗
PubMed2006

Pathogenic monoclonal antibody against desmoglein 3 augments desmoglein 3 and p38 MAPK phosphorylation in human squamous carcinoma cell line.

Pemphigus vulgaris is an autoimmune blistering disease characterized by cell-cell detachment of epidermal cells. Autoantibody against desmoglein (Dsg) 3, a transmembrane glycoprotein that mediates the association of desmosomes, plays a major role in blistering in pemphigus vulgaris (PV). The mechanisms of autoantibody-induced acantholysis have not been clarified. We previously reported that PV-IgG induces phosphorylation of Dsg3, decreases Dsg3 on the cell surface and forms Dsg3-depleted desmosomes in cultured keratinocytes, and that cell treatment with a potent pathogenic monoclonal antibody against Dsg3 (AK23 mAb) decreases the amount of Dsg3 in cultured keratinocytes. Although the precise mechanisms remain unclear, we have proposed the involvement of intracellular signal transduction resulting from the binding of autoantibodies to Dsg3. In this study, we examined whether AK23 mAb augments phosphorylation of Dsg3 and p38 mitogen-activating protein kinase (MAPK) in a human squamous cell line, DJM-1 cells. AK23 mAb increased serine phosphorylation of Dsg3 and augmented activation levels of p38 MAPK. These results indicate that antibodies bind to Dsg3, but not other antigens, in the IgG fraction and can induce activation of signal transduction.

Adjuvants, Immunologic↗
PubMed2006

Bowen's disease with invasive adnexal carcinoma: the pluripotential nature of Bowen's disease cells.

Bowen's disease rarely exhibits multiple combinations of premalignant and/or malignant skin lesions. Bowen's disease with invasive adnexal carcinoma was originally described by Kao, but is not well recognized by clinicians due to its rarity and lack of specific clinical features of this condition. Herein, we describe three unusual cases of Bowen's disease with invasive adnexal carcinoma. The two distinct neoplastic areas exhibited continuity both clinically and histologically. The plaque lesions possessed clinical features typical of Bowen's disease. In cases 1 and 3, we confirmed the adnexal tumor within tumors of Bowen's disease, the diagnosis of which is eccrine porocarcinoma. The tumor in case 2 was characteristic to trichilemmal carcinoma. Immunohistochemically, the tumor cells of Bowen's disease and the adnexal carcinoma differed in antigenicities. The present cases support a notion that Bowen's disease maintains a pluripotential nature.

Acrospiroma↗
PubMed2006

[Autonomic nerve function in patients with systemic scleroderma using heart rate variability analysis].

We examined autonomic nerve function in patients with systemic scleroderma (SSc) using power spectral analysis of heart rate variability. In the SSc group, both in nighttime (0:00a.m.-5:00a.m.) and daytime (10:00a.m.-5:00p.m.), HF elements, a parasympathetic nerve index, were lower and LF/HF ratios, a sympathetic nerve index, were higher than in the control group. This suggests that in SSc patients, sympathetic nerve activity was increased and parasympathetic nerve activity was decreased throughout the day.

Adult↗
PubMed2005

Semisynthesis of human ghrelin: condensation of a Boc-protected recombinant peptide with a synthetic O-acylated fragment.

The creation of peptide using a combination of recombinant expression and chemical synthesis can be a powerful tool for the production of a wide variety of polypeptides modified by phosphorylation, glycosylation, etc. We have developed a new method for the preparation of a recombinant peptide with a free N(alpha)-amino group and protected N(epsilon)-amino groups, and have used this method in the semisynthesis of human ghrelin. Ghrelin, a natural ligand for growth hormone secretagogue receptor, is a 28-residue peptide with an essential n-octanoyl modification on Ser3. A 7-residue N-terminal fragment of ghrelin containing the octanoyl modification was prepared by Fmoc chemistry. In the preparation of it, all reactions were performed on the 2-chlorotrityl resin. Additionally, TBDMS and tBu turned out to be the most effective protection groups for the Ser3 and the Ser2, Ser6, respectively. For preparation of a 21-residue C-terminal fragment, we established a two-step protease processing method for the partially protected segment. A recombinant precursor peptide was Boc protected and subsequently cleaved using two distinct proteases, OmpT and Kex2. The peptides were then coupled to each other and, after deprotection, resulted in fully active human ghrelin.

Acylation↗
PubMed2005

Akt regulates thrombin-induced HSP27 phosphorylation in aortic smooth muscle cells: function at a point downstream from p38 MAP kinase.

We previously reported that p38 MAP kinase takes part in thrombin-induced HSP27 phosphorylation in aortic smooth muscle A10 cells. In the present study, we investigated whether Akt is involved in the phosphorylation of HSP27 and the role of adenylyl cyclase-cAMP system. Thrombin time-dependently induced the phosphorylation of heat shock protein 27 (HSP27) and Akt in aortic smooth muscle A10 cells. SB203580, a p38 MAP kinase inhibitor, significantly suppressed the thrombin-induced phosphorylation of Akt and the Akt inhibitor suppressed the phosphorylation of HSP27. Furthermore, the thrombin-induced phosphorylation of HSP27, p38 MAP kinase and Akt were decreased by dibutyryl-cAMP (DBcAMP). These results strongly suggest that Akt functions the thrombin-induced phosphorylation of HSP27 at a point downstream from p38 MAP kinase in aortic smooth muscle cells and the adenylyl cyclase-cAMP system is upstream regulator of the HSP27 phosphorylation in these cells.

Adenylyl Cyclases↗
PubMed2005

alphaB-crystallin is phosphorylated during myocardial infarction: involvement of platelet-derived growth factor-BB.

alphaB-crystallin is the most abundant low-molecular-weight heat shock protein in heart and recent studies have demonstrated that it plays a cardioprotective role during myocardial infarction both in vivo and in vitro. On the other hand, platelet-derived growth factor (PDGF), a potent serum mitogen, has been reported to improve cardiac function after myocardial infarction. In the present study, using a mouse myocardial infarction model, we investigated whether alphaB-crystallin is phosphorylated during myocardial infarction and the implication of PDGF-BB. Phosphorylation of alphaB-crystallin at Ser-59 was time dependently induced and plasma PDGF-BB levels were concomitantly increased. Moreover, PDGF-BB-stimulated phosphorylation of alphaB-crystallin was suppressed by SB203580, a specific inhibitor of p38 mitogen-activated protein (MAP) kinase, in primary cultured cardiac myocytes. Our results indicate that PDGF-BB induces phosphorylation of alphaB-crystallin via p38 MAP kinase during myocardial infarction.

Animals↗
PubMed2004

P2Y12 receptors play a significant role in the development of platelet microaggregation in patients with diabetes.

Ninety-eight diabetic patients (type 2) were studied together with 24 healthy normotensive controls. Microaggregates (particle scale, <25 microm) of platelets were detected by a laser scattering system. Microaggregates in the control group showed a time-dependent reversible change; however, they existed continuously in 82 of 98 diabetic patients. When platelets of diabetics were stimulated by a shear stress alone without ADP, 74 also showed spontaneous and irreversible microaggregates even though they were not observed in all control subjects. In control subjects, microaggregates were inhibited by MRS2279 (a P2Y1 antagonist), but not AR-C69931MX (a P2Y12 antagonist). However, AR-C69931MX prevented irreversible microaggregates in diabetic patients. When either aspirin or ticlopidine was administered to diabetic patients with irreversible microaggregates, both drugs significantly decreased microaggregates induced by a low dose of ADP. Ticlopidine additionally reduced the microaggregates induced by shear stress alone. In conclusion, microaggregates of platelets via P2Y12 receptors could play a key role in the hypersensitivity of platelets in diabetic patients, and the measurement of microaggregation could be a useful marker to estimate of thrombogenesis. These findings present a possible new means for patients with diabetes to prevent ischemic events.

Adenosine Diphosphate↗
PubMed2004

Synergistic control of keratinocyte adhesion through muscarinic and nicotinic acetylcholine receptor subtypes.

The biological mechanisms involved in initiating, coordinating, and ultimately terminating cell-cell adhesion in the stratified epithelium are not well understood at present. This study was designed to elucidate the roles of the muscarinic M3, the nicotinic alpha3, and the mixed muscarinic-nicotinic alpha9 acetylcholine receptors in physiologic control of keratinocyte adhesion. Both muscarinic and nicotinic antagonists caused keratinocyte detachment and reversibly increased the permeability of keratinocyte monolayers, indicative of the involvement of both muscarinic and nicotinic pathways in the cholinergic control of keratinocyte adhesion. Since phosphorylation of adhesion proteins plays an important role in rapid assembly and disassembly of intercellular junctions, we measured muscarinic and nicotinic effects on phosphorylation of keratinocyte adhesion molecules. The phosphorylation levels of E-cadherin, beta-catenin, and gamma-catenin increased following pharmacological blockage of muscarinic receptors. Long-term blocking of alpha3, alpha9, and M3 receptor signaling pathways with antisense oligonucleotides resulted in cell-cell detachment and changes in the expression levels of E-cadherin, beta-catenin, and gamma-catenin in cultured human keratinocytes. Simultaneous inhibition of several receptor subtypes with a mixture of antisense oligonucleotides produced intensified abnormalities with cell adhesion. Moreover, altered cell-cell adhesion was found in the stratified epithelium of alpha3, alpha9, and M3 receptor knockout mice. Keratinocytes from these mice exhibited abnormal expression of adhesion molecules at both the protein and the mRNA levels. Thus, our data indicate that the alpha3, alpha9, and M3 acetylcholine receptors play key roles in regulating in a synergistic mode keratinocyte adhesion, most probably by modulating cadherin and catenin levels and activities. These findings may aid in the development of novel methods useful for the treatment of skin adhesion diseases and tumor metastasis.

Animals↗
PubMed2004

Pemphigus vulgaris acantholysis ameliorated by cholinergic agonists.

BACKGROUND: Pemphigus vulgaris (PV) is an autoimmune, IgG autoantibody-mediated disease of skin and mucosa leading to progressive blistering and nonhealing erosions. Patients develop autoantibodies to adhesion molecules mediating intercellular adhesion and to keratinocyte cholinergic receptors regulating cell adhesion. OBSERVATIONS: To determine whether a cholinergic agonist can abolish PV IgG-induced acantholysis, litter mates of neonatal athymic nude mice were injected with PV IgG together with carbachol (0.04 micro g/g body weight). None of these mice developed skin lesions. Through in vitro experiments, we measured the expression of adhesion molecules in monolayers of normal human keratinocytes incubated overnight in the presence of 0.25mM carbachol using semiquantitative Western blot and immunofluorescence. Carbachol caused an elevation of the relative amount of E-cadherin in keratinocytes (P<.05) without changing that of plakoglobin (P>.05). The phosphorylation level of E-cadherin and plakoglobin was increased by PV IgG, whereas this effect of PV IgG was attenuated in the presence of 0.5mM carbachol. Pyridostigmine bromide, an acetylcholinesterase inhibitor, produced effects similar to those of carbachol, which helps explain its clinical efficacy in a patient with active PV that was resistant to treatment with systemic glucocorticosteroids. Treatment with pyridostigmine bromide (360 mg/d) in a patient with PV allowed to keep his disease under control at a lower dose of prednisone than that used before starting pyridostigmine bromide treatment. Conclusion Elucidation of the cholinergic control of keratinocyte adhesion merits further consideration because of a potential for the development of novel antiacantholytic therapies using cholinergic drugs.

Acantholysis↗
PubMed2004

Possible involvement of p44/p42 MAP kinase in retinoic acid-stimulated vascular endothelial growth factor release in aortic smooth muscle cells.

Retinoic acid modulates cell growth and differentiation of the vascular system. Vascular endothelial growth factor (VEGF) is known as a vascular permeability factor and a potent mitogen for vascular endothelial cells. In the present study, we investigated whether retinoic acid induces VEGF release in aortic smooth muscle A10 cells and if so, the mechanism of VEGF release. Retinoic acid stimulated VEGF release dose-dependently over the range 0.1 nM-0.1 microM. The retinoic acid-stimulated VEGF release was significantly reduced by actinomycin D. Retinoic acid induced the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase but not p38 MAP kinase or stress-activated protein kinase/c-Jun N-terminal kinase among the MAP kinase superfamily. This effect of retinoic acid was dose-dependent (30 nM-5 microM) and the maximum effect was observed at 0.3 microM. The retinoic acid-stimulated release of VEGF was significantly reduced by PD98059 and U0126, specific MEK inhibitors, which attenuated the retinoic acid-induced phosphorylation of p44/p42 MAP kinase. These results strongly suggest that retinoic acid stimulates the release of VEGF in a p44/p42 MAP kinase-dependent manner in aortic smooth muscle cells.

Animals↗
PubMed2004

Monitoring of ELISA for anti-BP180 antibodies: clinical and therapeutic analysis of steroid-treated patients with bullous pemphigoid.

We studied the precise correlation between ELISA values for BP180 NC16A and the alternations of disease activity in 5 patients with bullous pemphigoid (BP) during various treatments and tried to answer the question of how we can use ELISA to determine the timing of prednisolone (PSL) tapering. Disease activity in some patients with BP, but not in all, was poorly correlated with ELISA values in short-term follow-up. However, all patients showed a good correlation of disease activity with ELISA values as a whole in long-term follow-up. Three patients with typical BP showed rapid and good responses to PSL for erosion and blister formation. Their ELISA values gradually decreased to 40% of initial values during PSL therapy after four weeks. Two patients with the vesicular type of BP did not show rapid and good responses to PSL for erosion and blister formation. In the cases with the vesicular type of BP, diaphenylsulfone in addition to PSL dramatically improved the clinical symptoms including erosion and blister formation, even though the ELISA values were as high as those before treatment. Relapses did not occur with the tapering of PSL dosage when the ELISA values decreased to 40% of initial values, although they were still not within the normal range.

Aged↗
PubMed2004

[Significance of the cardiovascular function tests in patients with collagen diseases, especially for SSc (systemic scleroderma)].

The purpose of this study is to evaluate the cardiovascular function in patients with incomplete type of SSc (SSSD; Scleroderma Sjögren syndrome associated Spectrum Disorders), SSc (Systemic Scleroderma) and SLE (Systemic Lupus Erythematosus) by using ECG and digital plethysmograph. We also preformed ambulatory ECG monitoring for cases of SSSD and SSc with QT interval prolongation. 1) In ECG findings, ischemic myocardial damage, left ventricular hypertrophy or QT interval prolongation was observed in 33% cases of SSSD and 32% cases of SSc, respectively. In addition, parasympathetic disorders were observed in approximately 20% cases of SSSD, SSc and SLE. 2) Digital plethysmogram findings suggested that the peripheral vascular damage was present in both cases of SSSD and SSc, and its severity was lower in SSSD than SSc. The incidence of abnormal cardiovascular function tests in SSSD was relatively less than that in SSc. The cardiovascular function tests are useful to find cardiovascular abnormalities in these collagen diseases.

Adult↗
PubMed2003

Pemphigus vulgaris IgG and methylprednisolone exhibit reciprocal effects on keratinocytes.

Pemphigus vulgaris (PV) is a life-threatening autoimmune disease of skin adhesion associated with IgG autoantibodies against keratinocytes (KC). Treatment of PV with systemic corticosteroids is life-saving, but the mechanism of the therapeutic action has not been fully understood. We have developed an animal model that demonstrates that methylprednisolone (MP) can block PV IgG-induced acantholysis, decreasing the extent of keratinocyte detachment in the epidermis of 3-5-day-old nude mice from 77.5 +/- 0.6 to 24.1 +/- 1.5% (p < 0.05). We hypothesized that in addition to immunosuppression, MP may exhibit direct anti-acantholytic effects in epidermis, and we compared the effects of PV IgG and MP on KC. The use of DNA microarray showed that PV IgG down-regulated and MP up-regulated expression of the genes encoding keratinocyte adhesion molecules, antigen-processing proteins, regulators of cell cycle and apoptosis, differentiation markers, Na+,K+-ATPase, protein kinases and phosphatases, and serine proteases and their inhibitors. Overall, PV IgG decreased transcription of 198 genes and increased transcription of 31 genes. MP decreased transcription of 14 genes and increased transcription of 818 genes. Specific effects of PV IgG and MP on keratinocyte adhesion molecules were further investigated by Western blot and immunofluorescence assays. By immunoblotting, MP increased the protein levels of E-cadherin and desmogleins 1 and 3 by 300, 180, and 40%, respectively. Specific staining of KC for E-cadherin and desmogleins 1 and 3 increased by 235, 228, and 148%, respectively. In addition, PV IgG increased the level of phosphorylation of E-cadherin by 42%, beta-catenin by 37%, gamma-catenin by 136%, and desmoglein 3 by 300%, whereas pretreatment with 0.25 mm MP abolished phosphorylation of these adhesion molecules. These results suggested that therapeutic effects of MP in PV include both the up-regulated synthesis and post-translational modification of the keratinocyte adhesion molecules.

Animals↗
PubMed2003

Loss of kindlin-1, a human homolog of the Caenorhabditis elegans actin-extracellular-matrix linker protein UNC-112, causes Kindler syndrome.

Kindler syndrome is an autosomal recessive disorder characterized by neonatal blistering, sun sensitivity, atrophy, abnormal pigmentation, and fragility of the skin. Linkage and homozygosity analysis in an isolated Panamanian cohort and in additional inbred families mapped the gene to 20p12.3. Loss-of-function mutations were identified in the FLJ20116 gene (renamed "KIND1" [encoding kindlin-1]). Kindlin-1 is a human homolog of the Caenorhabditis elegans protein UNC-112, a membrane-associated structural/signaling protein that has been implicated in linking the actin cytoskeleton to the extracellular matrix (ECM). Thus, Kindler syndrome is, to our knowledge, the first skin fragility disorder caused by a defect in actin-ECM linkage, rather than keratin-ECM linkage.

Abnormalities, Multiple↗
PubMed2003

Keratinocyte acetylcholine receptors regulate cell adhesion.

We investigated the mechanism mediating cholinergic control of cell-to-cell adhesion of human epidermal keratinocytes (KC) by non-neuronal acetylcholine produced by KC themselves. We first measured cholinergic effects on the expression of desmoglein (Dsg) 1 and 3 in KC using the semi-quantitative immunofluorescence and Western blot assays. Monolayers of KC were treated overnight with 0.25 mM of the cholinergic agonist carbachol (CCh) or the acetylcholinesterase inhibitor pyridostigmine bromide (PBr). Both CCh and PBr increased the relative amounts of Dsg 1 and Dsg 3. To determine the role for cholinergic receptor-mediated phosphorylation of Dsg molecules in assembly/disassembly of keratinocyte desmosomes, we tested the effects of a cholinergic antagonist on keratinocyte adhesion and Dsg phosphorylation status in DJM-1 cell line. Atropine (Atr), 0.02 mM, induced rapid detachment of cells from each other (acantholysis), and also increased phosphorylation of Dsg 3 by 33%. The Atr-dependent phosphorylation of Dsg 3 was inhibited in the presence of 0.5 mM CCh. Thus, keratinocyte cholinergic receptors regulate desmosomal adhesion of KC by altering the level of expression of both Dsg 1 and Dsg 3 and the phosphorylation status of Dsg 3.

Acetylcholine↗