Type-specific Manner (type-specific + manner)

Distribution by Scientific Domains

Kinds of Type-specific Manner

  • cell type-specific manner

  • Selected Abstracts

    Post-translational and cell type-specific regulation of CXCR4 expression by cytokines

    Hilke Brühl
    Abstract We have investigated the regulation and function of the chemokine receptor CXCR4 on neutrophils. CXCR4 is hardly detectable on neutrophils in the peripheral blood. However, overnight culture strongly up-regulates CXCR4 expression on the cell surface. The functional activity of CXCR4 on cultured neutrophils was confirmed by stromal cell-derived factor (SDF)-induced migration and up-regulation of the integrins CD11b and CD11c. CXCR4 surface expression on neutrophils but not on lymphocytes and monocytes is rapidly down-regulated after stimulation with TNF-, and IFN-,, resulting in significantly decreased SDF-induced functional responses of neutrophils. In contrast to surface expression, CXCR4 mRNA expression was several-fold increased in cytokine-stimulated neutrophils, suggesting a post-translational regulation. By confocal microscopy we demonstrate that CXCR4 is internalized after stimulation with TNF-, and IFN-,. The down-modulation of CXCR4 surface expression in response to TNF-, and IFN-, was fully reversible after cytokine removal. Further, CXCR4 down-modulation could be completely blocked by hypertonic sucrose and significantly reduced by chlorpromazine indicating the involvement of clathrin-coated pits. Internalization of CXCR4 by cytokines in a cell type-specific manner is a novel and functionally important mechanism of chemokine receptor regulation. [source]

    Alterations of pre-mRNA splicing in cancer

    Zane Kalnin
    Recent genomewide analyses of alternative splicing (AS) indicate that up to 70% of human genes may have alternative splice forms, suggesting that AS together with various posttranslational modifications plays a major role in the production of proteome complexity. Splice-site selection under normal physiological conditions is regulated in the developmental stage in a tissue type-specific manner by changing the concentrations and the activity of splicing regulatory proteins. Whereas spliceosomal errors resulting in the production of aberrant transcripts rarely occur in normal cells, they seem to be an intrinsic property of cancer cells. Changes in splice-site selection have been observed in various types of cancer and may affect genes implicated in tumor progression (for example, CD44, MDM2, and FHIT) and in susceptibility to cancer (for example, BRCA1 and APC). Splicing defects can arise from inherited or somatic mutations in cis -acting regulatory elements (splice donor, acceptor and branch sites, and exonic and intronic splicing enhancers and silencers) or variations in the composition, concentration, localization, and activity of regulatory proteins. This may lead to altered efficiency of splice-site recognition, resulting in overexpression or down-regulation of certain splice variants, a switch in splice-site usage, or failure to recognize splice sites correctly, resulting in cancer-specific splice forms. At least in some cases, changes in splicing have been shown to play a functionally significant role in tumorigenesis, either by inactivating tumor suppressors or by gain of function of proteins promoting tumor development. Moreover, cancer-specific splicing events may generate novel epitopes that can be recognized by the host's immune system as cancer specific and may serve as targets for immunotherapy. Thus, the identification of cancer-specific splice forms provides a novel source for the discovery of diagnostic or prognostic biomarkers and tumor antigens suitable as targets for therapeutic intervention. © 2005 Wiley-Liss, Inc. [source]

    Modification of human papillomavirus-like particle vaccine by insertion of the cross-reactive L2-epitopes

    Kazunari Kondo
    Abstract Infection with human papillomavirus 16 (HPV16), which is one of the 15 types of HPV causally associated with cervical cancer and accounts for 50% of the cases, can be prevented in a type-specific manner by an HPV16 virus-like particle (VLP) vaccine comprised of particles of the L1 protein alone. We attempted to modify the VLP vaccine by inserting the HPV16 L2-peptides including cross-neutralization epitopes into the L1 polypeptide. The chimeric L1 had, between L1 amino acids (aa) 430 and 433, the L2 sequence of aa 18,38, 56,75, or 96,115 (with the replacements of S at aa 101 and T at aa 112 with L and S, respectively). The three chimeric L1s were each expressed from the recombinant baculovirus in insect Sf9 cells, and the resultant VLPs were characterized. The chimeric VLPs were shown to present the L2-peptides on their surface. By immunizing rabbits with the VLPs, it was shown that they retained capability to induce the antibody neutralizing HPV16 and acquired capability to elicit antibodies cross-neutralizing the infectious HPV18, 31, 52, and 58 pseudovirions. Although the cross-neutralizing titers were lower than the type-specific neutralizing titer, the results suggest that the chimeric VLPs have potential to serve as a vaccine candidate for a broad spectrum of high-risk HPVs. J. Med. Virol. 80:841,846, 2008. © 2008 Wiley-Liss, Inc. [source]

    Intratesticular localization of the organic solute carrier protein, OSCP1, in spermatogenic cells in mice

    Kazuyuki Hiratsuka
    Abstract Organic solute carrier protein 1 (OSCP1) is a recently described human gene that facilitates the transport of various organic solutes into the cell, when expressed in frog eggs. In this study, we cloned a mouse ortholog of OSCP1 encoding 379 amino acid protein, with 94% homology to the human counterpart. The mouse OSCP1 mRNA was predominantly expressed in the testis, in which it was attributed to the spermatogenic cells, except the spermatogonia. Immunohistochemistry confirmed that OSCP1 protein is continuously expressed during spermatogenesis in a stage- and cell type-specific manner, in the leptotene spermatocytes at stage IX through step 15 spermatids. Subcellular fractionation of mouse testis homogenates indicated that OSCP1 is a 45-kDa cytosolic protein. Moreover, when green fluorescent protein-OSCP1 fusion constructs were transfected into cultured cells, the fluorescence localized evenly in the cytoplasm. These results suggest that mouse testis OSCP1 may indirectly mediate substrate uptake into meiotic and spermiogenic germ cells, within the cytosol. Mol. Reprod. Dev. 75: 1495,1504 © 2008 Wiley-Liss, Inc. [source]

    ,-Catenin expression in human neural cell lines following exposure to cytokines and growth factors

    NEUROPATHOLOGY, Issue 2 2000
    Jun-ichi Satoh
    ,-Catenin acts as a key mediator of the Wnt/Wingless signaling pathway involved in cell proliferation, differentiation and survival. Recent studies have shown that an unstable interaction between ,-catenin and the mutant presenilin-1 induces neuronal apoptosis, and that ,-catenin levels are decreased in the brains of patients with Alzheimer's disease (AD). Since activated microglia and astrocytes play a role in the process of neuronal degeneration in AD, the cytokine/growth factor-regulated expression of ,-catenin in human neural cell lines, including NTera2 teratocarcinoma-derived differentiated neurons (NTera2-N), IMR-32 neuroblastoma, SKN-SH neuroblastoma and U-373MG astrocytoma, was studied quantitatively following exposure to epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), tumor necrosis factor-, (TNF-,), interleukin (IL)-1,, IL-6, interferon (IFN)-,, transforming growth factor (TGF)-,1, dibutyryl cyclic adenosine 3,,5,-cyclic monophosphate (cAMP) (dbcAMP) or phorbol 12-myristate 13-acetate (PMA). ,-Catenin mRNA expressed constitutively in all of these cell lines was unaffected by treatment with any factors examined. In contrast, ,-catenin protein levels were reduced markedly in NTera2-N cells by exposure to dbcAMP, EGF or bFGF, and in U-373MG cells by treatment with dbcAMP or PMA, but were unaffected in any cell lines by BDNF, TNF-,, IL-1,, IL-6, IFN-, or TGF-,1. These results indicate that ,-catenin is expressed constitutively in human neural cells and downregulated at a protein level by a set of growth factors in a cell type-specific manner. [source]

    Ligand-independent Regulation of the hairless Promoter by Vitamin D Receptor,

    Andrew Engelhard
    The characteristic alopecia associated with mutations in the hairless (hr) and vitamin D receptor (VDR) genes defines the resulting genetic disorders, known as atrichia and VDRRIIa rickets, as phenocopies. In both cases, the separation of the dermal papilla from the regressing hair follicle at the onset of the first catagen phase of the hair cycle and the development of dermal cysts and utricules subsequent to mutation of either gene suggests that their activities affect the same regulatory pathways. VDR functions as a hormonally activated transcription factor, and a role in transcription has been postulated for Hr due in part to its nuclear localization and homology with the GATA-1 zinc-finger domain. Therefore, we examined the hypothesis that VDR and Hr have a direct regulatory effect on each other via a transcriptional mechanism. Ectopic expression of the VDR repressed hr promoter activity in HaCaT cells and primary human keratinocytes (PHKs). While this repression occurs in the absence of 1,25 dihydroxyvitamin D3 (D3), the addition of ligand greatly augments the effect. However, we also demonstrate the rare phenomenon of ligand-independent promoter transactivation by VDR. We show that the full-length promoter is transactivated by VDR in a ligand-independent and cell type-specific manner, suggesting that direct transcriptional regulation of hr by the VDR accounts in part for the phenotypic overlap between atrichia and VDRRIIa rickets. [source]

    Expression of the nm23 homologues nm23-H4, nm23-H6, and nm23-H7 in human gastric and colon cancer

    M Seifert
    Abstract Eight members of the nm23-gene family have been described. The involvement of nm23-H1 and nm23-H2 in tumour progression and metastasis, as well as in gene regulation and apoptosis, has been shown in numerous studies. Whether nm23-H4, -H6, and -H7 play a role in tumours is, however, largely unknown. This study describes data on the expression of these three nm23 homologues in human colon and gastric cancer by real-time RT-PCR and immunohistochemistry. Increased expression of these genes, most strikingly nm23-H4 and -H7, was observed in the majority of tumours analysed. No correlation with tumour stage according to the TNM classification was found. In contrast, by immunohistochemical analysis, nm23-H4 and -H6 overexpression correlated with the intestinal tumour type in gastric cancer tissues, whereas no increased immunoreactivity for the three nm23 proteins was noted in the diffuse type tumour specimens. These findings indicate that nm23-H6, and particularly nm23-H4 and -H7, may be involved in the development of colon and gastric carcinoma, the latter possibly in a type-specific manner. A contribution to tumour progression or metastasis could not, however, be proven. Elucidation of the specific mechanisms by which the nm23 homologues nm23-H4, -H6, and -H7 are involved in tumour development requires further studies. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source]

    Intermolecular cross-talk between the prostaglandin E2 receptor (EP)3 subtype and thromboxane A2 receptor signalling in human erythroleukaemic cells

    Helen M Reid
    Background and purpose:, In previous studies investigating cross-talk of signalling between prostaglandin (PG)E2 receptor (EP) and the TP, and TP, isoforms of the human thromboxane (TX)A2 receptor (TP), 17-phenyl trinor PGE2 -induced desensitization of TP receptor signalling through activation of the AH6809 and SC19220-sensitive EP1 subtype of the EP receptor family, in a cell-specific manner. Here, we sought to further investigate that cross-talk in human erythroleukaemic (HEL) 92.1.7 cells. Experimental approach:, Specificity of 17-phenyl trinor PGE2 signalling and its possible cross-talk with signalling by TP,/TP, receptors endogenously expressed in HEL cells was examined through assessment of agonist-induced inositol 1,4,5-trisphosphate (IP)3 generation and intracellular calcium ([Ca2+]i) mobilization. Key results:, While 17-Phenyl trinor PGE2 led to activation of phospholipase (PL)C, to yield increases in IP3 generation and [Ca2+]i, it did not desensitize but rather augmented that signalling in response to subsequent stimulation with the TXA2 mimetic U46619. Furthermore, the augmentation was reciprocal. Signalling by 17-phenyl trinor PGE2 was found to occur through AH6809- and SC19920-insensitive, Pertussis toxin-sensitive, Gi/G,, -dependent activation of PLC,. Further pharmacological investigation using selective EP receptor subtype agonists and antagonists confirmed that 17-phenyl trinor PGE2 -mediated signalling and reciprocal cross-talk with the TP receptors occurred through the EP3, rather than the EP1, EP2 or EP4 receptor subtype in HEL cells. Conclusions and Implications:, The EP1 and EP3 subtypes of the EP receptor family mediated intermolecular cross-talk to differentially regulate TP receptor-mediated signalling whereby activation of EP1 receptors impaired or desensitized, while that of EP3 receptors augmented signalling through TP,/TP, receptors, in a cell type-specific manner. [source]