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Biomedical subjects

J Y Yi

Publications and source records attributed to J Y Yi.

At least 19 recordsLinked to original sources
PubMed2005

Activated type I TGFbeta receptor kinase enhances the survival of mammary epithelial cells and accelerates tumor progression.

We have examined the effects of transforming growth factor-beta (TGFbeta) signaling on mammary epithelial cell survival. Transgenic mice expressing an active mutant of Alk5 in the mammary gland (MMTV-Alk5(T204D)) exhibited reduced apoptosis in terminal endbuds and during postlactational involution. Transgene-expressing mammary cells contained lower Smad2/3 and higher c-myc levels than controls, high ligand-independent phosphatidylinositol-3 kinase (PI3K) and Akt activities, and were insensitive to TGFbeta-mediated growth arrest. Treatment with a proteasome inhibitor increased Smad2/3 levels and ligand-independent Smad transcriptional reporter activity, as well as reduced both c-myc protein and basal cell proliferation. Treatment with an Alk5 kinase small-molecule inhibitor upregulated Smad2/3 levels, reduced PI3K activity, P-Akt, and c-myc, and inhibited cell survival. Although Alk5(T204D)-expressing mice did not develop mammary tumors, bigenic MMTV-Alk(T204D) x Neu mice developed cancers that were more metastatic than those occurring in MMTV-Neu transgenics. These data suggest that (1) TGFbeta can signal to PI3K/Akt and enhance mammary epithelial cell survival in vivo before cytological or histological evidence of transformation, and (2) TGFbeta signaling can provide epithelial cells with a 'gain-of-function' effect that synergizes with oncogene-induced transformation.

Activin Receptors, Type I↗
PubMed2001

Calcipotriol inhibits autocrine phosphorylation of EGF receptor in a calcium-dependent manner, a possible mechanism for its inhibition of cell proliferation and stimulation of cell differentiation.

We report in this study that proliferation inhibition of SCC13 cells by calcipotriol was possibly mediated by its inhibitory effect on autocrine activation of EGF receptor. Based on MTT assay, PCNA staining, DAPI staining, and involucrin immunocytochemical staining, we showed that calcipotriol inhibited cell growth and stimulated differentiation but did not induce apoptosis. Western blot analysis of concanavalin-A-bound fraction demonstrated that calcipotriol specifically dephosphorylated 170- and 66-kDa polypeptides from 8 h posttreatment and complete dephosphorylation was observed at 12 h posttreatment. The 170- and 66-kDa polypeptides were confirmed as EGF receptor and Shc, respectively. Calcipotriol-mediated EGF receptor dephosphorylation required the presence of extracellular calcium. Similar kinetics of the dephosphorylation was also observed in HaCaT cells cultured in medium of high calcium concentration. By BrdU labeling, we also showed calcium dependency of calcipotriol for the inhibition of cell proliferation. Therefore, EGF receptor deactivation by calcipotriol might be a mechanism of action for the inhibition of cell proliferation and the stimulation of differentiation in SCC13 cell and HaCaT cells.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Reconstruction of basement membrane in skin equivalent; role of laminin-1.

To reconstruct the basement membrane in a skin equivalent, the epidermodermal interface was coated with porcine type IV collagen and mouse laminin-1 at various ratios before keratinocyte seeding. Laminin-1, a component of the basement membrane, induced massive infiltration of keratinocytes into the dermal equivalent, while type IV collagen induced discrete demarcation between dermal and epidermal compartments without any infiltrating cells. Immunohistochemical staining indicated that the laminin-induced infiltrating cells expressed endogenous type IV collagens at the cell periphery, which were not incorporated into the basement membrane structure. The infiltrating cells did not express fibronectin receptor alpha5beta1 integrin but showed MMP-9 secretion and cell surface associated MMP-2. However, when laminin-1 was preincubated with type IV collagen, laminin-1-induced keratinocyte infiltration as well as MMP-9 induction were almost completely suppressed to basal levels. Therefore, replenishment of the type IV collagen lattice seemed to cause laminin-stimulated cells to anchor to the lattice, in a similar manner to the basal cells on the basement membrane of normal skin. Our study suggests that the molar ratio of basement membrane components may determine the behavior of basal cells within the wound healing microenvironment, which is probably regulated either by extracellular matrix deposition or degradation.

3T3 Cells↗
PubMed2001

Identification of cDNA encoding a serine protease homologous to human complement C1r precursor from grafted mouse skin.

We isolated a cDNA clone from grafted mouse skin that encodes a serine protease homologous to human C1r. The C1r protease is involved in the activation of the first component of the classical pathway in the complement system. In order to identify novel transcripts whose expression is regulated in grafted mouse skin, we first performed differential display reverse transcription polymerase chain reaction analysis and obtained 18 partial cDNA clones whose protein products are likely to play an important role in allograft rejection. One of these showed significant sequence homology with human complement C1r precursor. The other clones displayed no homology to any known sequences, however. Northern blot analysis demonstrated that the level of this transcript was upregulated in day 8 postgrafted skin. The full-length cDNA 2121 nucleotides in length obtained from screening a mouse skin cDNA library contained a single open reading frame encoding 707 amino acid residues with a calculated molecular weight of 80,732 Da. Its deduced amino acid sequence revealed an 81% identity and 89% similarity to the human C1r counterpart. In particular, mouse C1r contained His501, Asp559, and Ser656, which were conserved among this group of serine proteases. This protein was thus designated as mouse C1r. We have expressed a truncated fragment of C1r protein without the N-terminal hydrophobic sequence in Escherichia coli and generated a polyclonal antibody against it. Subsequent immunohistochemical analysis confirmed that mouse C1r was significantly expressed 8 d after the skin graft in both allografted and autografted skins, compared with normal skins. These collective data suggest that a component of the complement system, C1r, might contribute to the graft versus host immune responses in mice.

Animals↗
PubMed2000

Clinical improvement and immunohistochemical findings in severe atopic dermatitis treated with interferon gamma.

BACKGROUND: Several clinical studies have focused on the therapeutic effects of interferon gamma (IFN-gamma) in patients with severe atopic dermatitis (AD), although the dosage of recombinant IFN-gamma (rIFN-gamma), therapeutic schedule, and the degree of clinical improvement were different among studies. Although the exact mechanism of action of IFN-gamma therapy in AD is not clear, the beneficial effects of IFN-gamma have been attributed mainly to an immunomodulating effect on the expression of certain immunologic markers. OBJECTIVE: Our purpose was to study the therapeutic effect of two different dosages of rIFN-gamma on AD and to investigate the change of lesional expression of infiltrating inflammatory cell markers associated with rIFN-gamma therapeutic efficacy. METHODS: Fifty-one patients with severe recalcitrant AD were treated with rIFN-gamma. Twenty patients were treated with 0.5 x 10(6) IU/m(2) of rIFN-gamma (low-dose [LD] group); 21 patients received 1.5 x 10(6) IU/m(2) of rIFN-gamma (high-dose [HD] group); and 10 patients received placebo. The patients were injected subcutaneously 3 times a week for 12 weeks. Immunohistochemical study was performed in 20 patients of the HD group in the initial visit and after completion of rIFN-gamma therapy with a panel of 14 monoclonal antibodies as markers of inflammatory cells and cytokines. RESULTS: The disease severity of the 2 groups treated with rIFN-gamma was reduced significantly at the end of treatment compared with that of the placebo group (P<.05). More rapid clinical improvement and more effective treatment outcome were seen in the HD group than in the LD group for the initial 6-week treatment period; however, the clinical improvement in both of the treated groups was stable and maintained after week 8 of treatment. Immunohistochemical findings showed statistically significant reduction in the lesional expression of CD25 and EG2 cells that infiltrated into skin after rIFN-gamma therapy. CONCLUSION: This study demonstrated that rIFN-gamma therapy for AD is safe and effective. In the early phase of therapy, a higher dosage of rIFN-gamma is more effective; and for the maintenance of clinical improvement, a lower dosage of rIFN-gamma is recommended when high cost and effectiveness of rIFN-gamma are considered. The therapeutic efficacy of rIFN-gamma in AD might be in part related to the decreased number of CD25(+) and EG2(+) inflammatory cells infiltrated into skin.

Adolescent↗
PubMed1999

Activating signal cointegrator 1, a novel transcription coactivator of nuclear receptors, and its cytosolic localization under conditions of serum deprivation.

Activating signal cointegrator 1 (ASC-1) harbors an autonomous transactivation domain that contains a putative zinc finger motif which provides binding sites for basal transcription factors TBP and TFIIA, transcription integrators steroid receptor coactivator 1 (SRC-1) and CBP-p300, and nuclear receptors, as demonstrated by the glutathione S-transferase pull-down assays and the yeast two-hybrid tests. The ASC-1 binding sites involve the hinge domain but not the C-terminal AF2 core domain of nuclear receptors. Nonetheless, ASC-1 appears to require the AF2-dependent factors to function (i.e., CBP-p300 and SRC-1), as suggested by the ability of ASC-1 to coactivate nuclear receptors, either alone or in cooperation with SRC-1 and p300, as well as its inability to coactivate a mutant receptor lacking the AF2 core domain. By using indirect immunofluorescence, we further show that ASC-1, a nuclear protein, is localized to the cytoplasm under conditions of serum deprivation but is retained in the nucleus when it is serum starved in the presence of ligand or coexpressed CBP or SRC-1. These results suggest that ASC-1 is a novel coactivator molecule of nuclear receptors which functions in conjunction with CBP-p300 and SRC-1 and may play an important role in establishing distinct coactivator complexes under different cellular conditions.

Amino Acid Sequence↗
PubMed1998

Rac GTPase activity is essential for EGF-induced mitogenesis.

Rac, a member of the Rho family GTPases, has been implicated in the regulation of a wide range of biological processes including actin remodeling, cell transformation, G1 cell cycle progression, and gene expression. To determine whether Rac GTPase activity is required for epidermal growth factor-induced mitogenesis, Rat-2 stable cells expressing a dominant-negative Rac1 mutant, RacN17, were prepared. Exposure to EGF exhibited a significantly restricted growth response in Rat-2-RacN17 cells compared to Rat-2 parental cells, suggesting an essential role of Rac in EGF-induced mitogenesis. In contrast, addition of lysophosphatidic acid exerted the same level of growth in Rat-2 and Rat-2-RacN17 cells. To gain further evidence for the essential role of Rac in EGF-induced mitogenesis, we performed the microinjection experiment. EGF-induced DNA synthesis was significantly blocked by microinjection of recombinant RacN17 protein, and not control IgG. Our further study to analyze the downstream mediator of Rac in EGF-signaling to mitogenesis demonstrated that Rac-activated phospholipase A2 plays a critical role. Taken together, our results suggest that the "Rac and Rac-activated PLA2" cascade is one of the major mitogenic pathways induced by EGF.

Animals↗
PubMed1998

Reduced activity of topoisomerase II in an Adriamycin-resistant human stomach-adenocarcinoma cell line.

A human stomach-adenocarcinoma cell line (MKN-45) was selected for resistance to Adriamycin by stepwise exposure to increasing concentrations of this agent. The resulting cell line (MKN/ADR) exhibited a high level of cross-resistance to topoisomerase II (topo II)-targeted drugs such as Adriamycin, mitoxantrone, and etoposide but showed no cross-resistance to other chemotherapeutic agents such as cisplatin, carboplatin, 5-fluorouracil, or mitomycin-C. P-glycoprotein encoded by the mdr-1 gene was not overexpressed in the MKN/ADR cell line. The doubling time of the MKN/ADR cell line (2.1 days) increased only slightly as compared with that of the MKN cell line (1.7 days). The patterns of cross-resistance to various chemotherapeutic agents led us to examine the cellular contents of topo II in both the drug-sensitive and the drug-resistant cells. Extractable topo II enzyme activity was 3-fold lower in MKN/ADR cells as compared with the parental MKN cells. Levels of topoisomerase I (topo I) catalytic activity were similar in both wild-type MKN and drug-resistant MKN/ADR cells. Southern-blot analysis of genomic DNA probed with topo IIalpha or IIbeta showed no sign of either gene rearrangement or hypermethylation. Northern-blot analysis revealed that both topo IIalpha and topo IIbeta mRNA transcripts were essentially identical in the MKN and MKN/ADR cells. In contrast, Western-blot analysis revealed an approximately 20-fold lower level of topo IIalpha in drug-resistant cells as compared with drug-sensitive cells, whereas topo IIbeta levels were similar in both lines. Moreover, the amount of in vivo topo IIalpha-DNA covalent complexes formed in the presence of etoposide was also approximately 20-fold lower in drug-resistant cells. No mutation was detected in the promoter region of the topo IIalpha gene in resistant cells as compared with sensitive cells. Thus, low levels of topo IIalpha polypeptide cannot be ascribed to changes in the mRNA levels. Collectively, the data suggest that a quantitative reduction in topo IIalpha may contribute to the resistance of MKN cells to Adriamycin and other topo II-targeted drugs.

Adenocarcinoma↗
PubMed1997

Histopathological findings, viral DNA distribution and lymphocytic immunophenotypes in vesicular and papular types of herpes zoster.

The characteristics rash of herpes zoster begins as erythematous macules and papules, progressing to vesicles within 12-24 h. Patients with persistent papules without vesicular change are occasionally found. Our aim was to elucidate differences in vesicular and papular types of herpes zoster. Biopsy specimens from 21 patients were examined by an in situ hybridization method to observe viral distribution, and lymphocytic immunophenotypes were evaluated immunohistochemically. There was no differences in cell-mediated immunity or immunophenotypes in lymphocytic infiltrates between vesicular and papular types of herpes zoster. DNA of varicella-zoster virus was detected in the epidermis and hair follicles in the vesicular type but was found in the pilosebaceous unit in the papular type. This indicates that the appearance of clinical types of herpes zoster depends on the infected site of varicella-zoster virus in the tissue.

Adolescent↗
PubMed1996

A new classification scheme for hypertension based on relative and absolute risk with implications for treatment and reimbursement.

Classification schemes for hypertension are necessary. They provide us with definitions for when hypertension begins and help us to assess risk, determine prognosis, and guide management. Systems in current use rely on either the level of blood pressure (diastolic, systolic, or both) and classify patients based on the level of relative risk (the proportional likelihood of cardiovascular events occurring as blood pressure rises), absolute risk (the actual odds that a patient or a population will develop an event), or both. Absolute risk reflects the sum of all the factors that contribute to the likelihood that a patient will experience cardiovascular disease. The system we propose stages hypertensive individuals on the basis of blood pressure level (as does the Fifth Joint National Committee report on the detection, evaluation, and treatment of high blood pressure [JNC-V] and the World Health Organization/International Society of Hypertension guidelines) but uses different levels for each stage than do the previous systems and then modifies the numerical stage with the subscript "c" for complicated (when target-organ damage and/or other cardiovascular risk factors are present) or "u" for uncomplicated (when they are absent). The data obtained from a complete medical history and physical examination and a few inexpensive laboratory tests provide the information a provider needs to classify an individual as being complicated or uncomplicated. This system also provides a guide to treatment, as drug therapy would be used sooner in individuals with complicated hypertension, and we propose that compensation for providers be higher when they are caring for a patient with complicated rather than uncomplicated hypertension.

Humans↗
PubMed1995

All-trans retinoic acid induces cellular retinol-binding protein in human skin in vivo.

We examined the regulation of cellular retinol-binding protein (CRBP) mRNA and protein expression in human skin in vivo by all-trans retinoic acid and all-trans retinol. Treatment of human skin for 24 h with all-trans retinoic acid (0.1%) or all-trans retinol (1.6%) induced CRBP mRNA 5.5-fold (p < 0.01, n = 10) and 5.7-fold (p < 0.01, n = 5), respectively, compared with skin treated with vehicle or sodium lauryl sulfate (used as an irritant control). In vitro translation of poly A+ RNA from all-trans retinoic acid, all-trans retinol, sodium lauryl sulfate, and vehicle-treated human skin demonstrated that the observed increased CRBP mRNA in all-trans retinoic acid- and all-trans retinol-treated skin was able to direct increased (2.3-2.9-fold) CRBP protein synthesis. Riboprobe in situ hybridization revealed that CRBP mRNA was uniformly elevated throughout the epidermis and in dermal cells after all-trans retinoic acid treatment of human skin. Western analysis revealed that CRBP protein was elevated 3.2-fold (p < 0.01, n = 6) and 3.0-fold (p < 0.01, n = 6) after all-trans retinoic acid treatment of human skin in vivo for 24 and 96 h, respectively, compared with vehicle- and sodium lauryl sulfate-treated skin. In addition, functional CRBP levels measured by [3H]all-trans retinol binding were elevated 1.9-fold (p < 0.01, n = 6) and 3.5-fold (p < 0.01, n = 6) at 24 and 94 h, respectively, after all-trans retinoic acid treatment, compared with vehicle- or sodium lauryl sulfate-treated skin. Gel mobility shift analysis revealed that retinoid receptors in nuclear extracts from human skin formed a specific complex with a DNA probe containing the retinoic acid response element in the mouse CRBP gene. Monoclonal antibodies to nuclear retinoid receptors demonstrated that predominantly retinoic acid receptor-alpha/retinoid X receptor-alpha heterodimers bound to the CRBP retinoic acid response element. These data demonstrate that CRBP expression in human skin in vivo is regulated by exogenous all-trans retinoic acid and all-trans retinol.

Base Sequence↗
PubMed1995

Application of retinol to human skin in vivo induces epidermal hyperplasia and cellular retinoid binding proteins characteristic of retinoic acid but without measurable retinoic acid levels or irritation.

We investigated the clinical, histologic, and molecular responses of normal human skin to all-trans-retinol (ROL) application, compared to those induced by topical all-trans-retinoic acid (RA), and measured ROL-derived metabolites. Up to 1.6% ROL, 0.025% RA in vehicle (70% ethanol/30% propylene glycol), or vehicle alone were applied in a double-blind fashion to normal buttock skin and occluded for 4 d. ROL produced from none to only trace erythema, which was clinically and statistically insignificant, whereas RA induced a significant 3.7-fold increase in erythema score compared to vehicle (n = 10, p < 0.01). However, ROL induced significant epidermal thickening (1.5-fold at 1.6% ROL, p < 0.01), similar to RA (1.6-fold at 0.025% RA, p < 0.01), relative to the vehicle. ROL, compared with vehicle, also increased mRNA levels of cellular retinoic acid binding protein (CRABP-II) and cellular retinol binding protein (CRBP) genes as determined by Northern analysis (5-6-fold and 6-7-fold, respectively) and riboprobe in situ hybridization. CRABP-II and CRBP protein levels were also higher following ROL than vehicle treatment, as measured by ligand binding (3.2-fold, p < 0.001; n = 7) and Western analysis (3.6-fold, p < 0.003; n = 6), respectively. Epidermal retinyl ester (RE) content, measured after removal of stratum corneum, rose 240-fold (p < 0.005, n = 5) by 24 h of ROL occlusion. RA content, however, was undetectable or detectable only at trace amounts in all samples obtained at 0, 6, 24, and 96 h after ROL occlusion. Detectability of RA was not correlated with ROL treatment (compared to untreated normal skin, p = 0.86) or baseline skin ROL levels (average r = -0.1, p > 0.3). These data demonstrate that ROL application 1) produces trace erythema not significantly different from vehicle, whereas RA causes erythema; 2) induces epidermal thickening and enhances expression of CRABP-II and CRBP mRNAs and proteins as does RA; 3) causes marked accumulation of retinyl ester; and 4) does not significantly increase RA levels. Taken together, the data are compatible with the idea that ROL may be a prohormone of RA, because it produces changes in skin similar to those produced by RA but without measurable RA or irritation.

Administration, Cutaneous↗