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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To examine the role of nuclear retinoic acid (RA) receptors (RARs) in the regulation of squamous differentiation in normal human epidermal keratinocytes (NHEK), we analyzed binding activity, mRNA expression, and transcriptional activity of the endogenously expressed RARs. Specific RA-binding activity eluted from size-exclusion HPLC with an apparent mol wt of 50 kilodaltons and was predominantly (greater than 95%) associated with the NHEK nuclear cell fraction. This RAR-binding activity represented in part the expression of RAR alpha and RAR gamma genes, whose transcripts were expressed in similar abundance in undifferentiated NHEK. Differentiation resulted in lower mRNA expression of RAR alpha relative to the mRNA expression of RAR gamma. Treatment of NHEK cells with 10(-6) M RA did not induce expression of RAR beta mRNA. Similarly, three squamous cell carcinoma cell lines derived from human skin and oral cavity expressed RAR alpha and RAR gamma transcripts, but not RAR beta transcripts. Transfection of NHEK with chloramphenicol acetyltransferase (CAT) reporter plasmids indicated that the endogenously expressed RARs could activate transcription through the RAR beta response element in a concentration-dependent manner with doses of 10(-9) M RA and higher. CAT expression was not activated through TRE, a palindromic thyroid hormone response element with purported RA responsiveness. The competitive binding of benzoic acid derivatives of RA to RAR correlated with the ability of each analog to suppress mRNA expression of the squamous cell markers, involucrin, type I transglutaminase, and SQ37, and to activate transcription of the RAR beta response element-CAT reporter. These results demonstrate that the control of NHEK differentiation by RA is consistent with the interaction of the retinoid with RAR and the regulation of transcription by that ligand-receptor complex.
Mol Endocrinol 1992 May
PMID:Retinoic acid receptors as regulators of human epidermal keratinocyte differentiation. 131 2

From a liver metastasis of a human pancreatic adenocarcinoma, we have established cell lines for studying the cell biology of this tumor. We obtained two cell lines with different morphological, chromosomal and functional properties. One of them, named PaTu 8988s, revealed a solid growth in nude mouse xenografts with cells exhibiting only occasional polar organisation of the cytoplasm. In general, no apical or basolateral plasma membrane domains could be distinguished and the sparse organelles were randomly distributed throughout the cytoplasm. Secretory products, such as mucin, were weakly stained histochemically or were completely absent. Transglutaminase (TGase) activity used as a marker for cellular differentiation was low in these cells. The other cell line, named PaTu 8988t, grew tumors composed of tubular structures when injected subcutaneously into nude mice. Cells were polarized with distinct apical and basolateral plasma membranes and the cytoplasmatic organelles were arranged with the nucleus in the lower part of the cell, while the apical cytoplasm contained the Golgi complex and numerous secretion granules. A high content of mucin was stained histochemically and transglutaminase activity was ten times higher than in PaTu 8988s. Comparing the chromosome number per metaphase plate, both cell lines showed a major peak, with 45-55 chromosomes per metaphase plate in PaTu 8988s and about 110-120 chromosomes per metaphase plate in PaTu 8988t. When the two cell lines were injected intravenously into the tail vein of nude mice, only PaTu 8988s developed metastases localized exclusively in the lung, whereas PaTu 8988t produced no metastases in any organ. We conclude, that two cell lines exhibiting different grades of differentiation as well as a different potency to metastasize can be established from the same primary tumor, and that these cell lines represent a suitable model for further study of the cell biology of human pancreatic adenocarcinoma.
Virchows Arch B Cell Pathol Incl Mol Pathol 1992
PMID:Establishment and characterisation of two cell lines with different grade of differentiation derived from one primary human pancreatic adenocarcinoma. 134 91

The Dunning tumor, originally described as a carcinoma of the rat dorsal prostate, has for long been used as an experimental model of prostatic cancer. We have recently presented a number of morphological findings that are incompatible with the prostatic origin of the H-subline of the Dunning tumor. In this paper, biochemical and immunohistochemical markers of rat prostate and mammary gland are studied in the R-3327 Dunning H tumor. Pieces of the H tumor were inoculated in male or lactating female rats. The electrophoretic protein pattern of Dunning tumor extracts was more similar to that of the mammary gland than the dorsolateral prostate. Proteins selectively appearing after metabolic labeling in Dunning tumors grown in lactating rats corresponded to labeled proteins in mammary glands from the same animals. Secretory proteins typical of the lateral prostate (SVS II) and dorsal prostate (transglutaminase) could not be detected immunohistochemically in the Dunning tumor. Western blot studies of tumor extracts and slot blot analysis of RNA preparations from the tumor confirmed the absence of SVS II and prostate specific transglutaminase from the Dunning tumor. On the other hand, the presence of mammary gland proteins such as milk fat globule membrane proteins, lactoperoxidase and lactalbumin were detected in the Dunning tumor by immunohistochemistry and Western blotting, but were absent from the dorsolateral prostate. Transferrin-mRNA, expressed in the male urogenital tract and also in the liver and other tissues, was detected in the mammary gland and Dunning tumor, but not in the dorsolateral prostate. The absence of mammary gland secretory beta-casein in the Dunning tumor was related to the elevated Ha-ras oncogene expression in the tumor, previously reported to suppress casein expression. The findings clearly demonstrate that the prostate cannot be the origin of the Dunning tumor, presently being used in prostatic cancer research. The designation prostatic adenocarcinoma for this tumor is therefore invalid. Furthermore, the data support our view that mammary gland might be the origin of the Dunning tumor, although the derivation from the bulbourethral or the parotid glands cannot strictly be excluded.
Virchows Arch B Cell Pathol Incl Mol Pathol 1992
PMID:Arguments against the prostatic origin of the R-3327 Dunning H tumor. 135 78

In cultured, undifferentiated normal human bronchial epithelial (HBE) cells, transglutaminase activity was localized predominantly in the cytosolic fraction of cell lysates. Upon squamous differentiation, this cytosolic activity declined and was replaced by a 40-fold increase in the activity of particulate (membrane-associated) transglutaminase. Immunoblot analysis demonstrated that the cytosolic transglutaminase was Type II (tissue) transglutaminase and that squamous differentiation shifted gene expression to the Type I (epidermal) transglutaminase. Retinoic acid, an inhibitor of squamous cell differentiation, suppressed the increase in Type I transglutaminase. The decrease in Type II transglutaminase activity was unaffected by retinoic acid. Transforming growth factor-beta 1 (TGF-beta 1) enhanced Type II transglutaminase activity about 10-fold in the undifferentiated cells but did not increase Type I transglutaminase or cholesterol sulfate, two early markers of squamous differentiation. TGF-beta 2 was equivalent to TGF-beta 1 in inducing Type II transglutaminase and in inhibiting the growth of HBE cells. The differentiation-related and TGF-beta-induced changes in transglutaminase activity were reflected in the level of transglutaminase Type I and Type II protein and mRNA. Expression of transglutaminases in lung carcinoma cell lines was variable. No correlation was observed between the expression of Type I transglutaminase and the classification of the cells as squamous cell carcinoma. Several lung carcinoma cell lines exhibited high levels of Type II transglutaminase activity that were increased several-fold by TGF-beta 1 treatment. Retinoic acid was ineffective in altering transglutaminase expression in most cell lines but induced Type II transglutaminase in a time- and dose-dependent manner in NCI-HUT-460 cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Am J Respir Cell Mol Biol 1992 Jul
PMID:Regulation of type I and type II transglutaminase in normal human bronchial epithelial and lung carcinoma cells. 135 92

Recently, we reported the presence of a putative transglutaminase in adult female worms of Brugia malayi [1]. The enzyme activity was shown to be essential for in utero growth and development of microfilariae. Here, we demonstrate that adult worms of B. malayi have a large amount of epsilon-(gamma-glutamyl)lysine isopeptide bonds, a product of physiologically active transglutaminase. A 25-kDa immunoreactive band detected in female worm extracts by a monospecific monoclonal antibody (CUB 7401) against guinea pig liver transglutaminase was associated with the enzymatic activity. Unlike the mammalian enzyme, the parasite enzyme did not require Ca2+ for its catalytic activity. Furthermore, in utero developing embryos, especially during early stages of development, contained very high amounts of this enzyme. Adult female worms contained several proteins that could serve as suitable substrates for the enzyme. Inhibition of the enzyme activity by an enzyme-specific pseudosubstrate, monodansylcadaverine, led to a time- and dose-dependent inhibition of microfilariae production and release by gravid female worms. The inhibition of microfilariae production was due to the inhibition of transglutaminase-catalyzed crosslinking of parasite proteins that in turn seemed to be essential for in utero growth and development of the embryos. The results suggest that transglutaminase-catalyzed reactions may play an important role during early development of embryos to mature microfilariae inside the adult female worms of filarial parasites.
Mol Biochem Parasitol 1992 Jul
PMID:Identification of a novel transglutaminase from the filarial parasite Brugia malayi and its role in growth and development. 135 28

Calcium-dependent transglutaminase (TGase) activity, determined by incorporation of [1,4-14C]diaminobutane dihydrochloride (putrescine) into casein, was demonstrated in a light membrane fraction prepared from bovine calf testicular homogenates. Purification of these membranes by sucrose density gradient centrifugation produced a follicle-stimulating hormone (FSH) receptor-enriched fraction containing TGase activity which cosolubilized with the FSH receptor and could be incorporated with detergent-solubilized receptor into liposomes. In the present study, we show that calcium increases specific binding of FSH to receptor in a concentration-related manner, and is associated with an increase (13.2-fold at 20 mM) in the affinity (Ka) of the receptor with no significant (P greater than 0.05) change in receptor concentration. Treatment of the light membrane fraction with monodansylcadaverine (MDC, 1 mM), a specific inhibitor of TGase, did not affect specific binding of FSH, but resulted in only a 3.9-fold increase in Ka at 20 mM calcium with no change in receptor concentration. Specific binding of FSH to receptor at 4 degrees C was also enhanced by calcium. Scatchard analysis of competitive binding inhibition data showed a Ka at 20 mM calcium similar to that observed with MDC. Dissociation of [125I]hFSH-receptor complexes formed at 30 degrees C in the presence of calcium was significantly less than dissociation of complexes formed at 30 degrees C in the absence of calcium. When [125I]hFSH-receptor complexes were formed at 30 degrees C in the presence of calcium and dissociated in calcium-deficient buffer, dissociation increased 3-fold. Similar results were obtained in the presence of MDC.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1992 Sep
PMID:Stabilization of follicle-stimulating hormone-receptor complexes may involve calcium-dependent transglutaminase activation. 135 84

The binding and internalization of 125I-endothelin (125I-ET-1) was studied in cultured human vascular smooth muscle cells (hVSMC). Discrimination between surface-bound and internalized radiolabeled ligand was achieved using either acetic acid or trypsin treatment of cell layers, with the two procedures yielding comparable results. Total cellular 125I-ET-1 binding hVSMC at 37 degrees was rapid and reached near equilibrium within 30 min. Such binding could be resolved into surface-bound (acid/trypsin-sensitive) and internalized (acid/trypsin-resistant) components. The accumulation of internalized 125I-ET-1 was temperature dependent and occurred at 37 degrees (t1/2 approximately 15 min) but not at 4 degrees. Internalization of 125I-ET-1 by hVSMC was reversibly inhibited by the transglutaminase inhibitor dansylcadaverine (half-maximal inhibitory concentration, approximately 400 microM). Cytosolic acidification of hVSMC (from pH approximately 6.8 to approximately 6.3) by incubation with potassium acetate in a choline buffer also inhibited 125I-ET-1 internalization. Our observation indicate that smooth muscle cells internalize ET-1 via the clathrin-mediated endocytotic pathway. Dansylcadaverine and other inhibitors of transglutaminase inhibited ET-1-stimulated inositol phospholipid hydrolysis in hVSMC and decreased ET-1-induced vasoconstriction in isolated endothelium-denuded blood vessels. Internalization of ET-1 may, therefore, be relevant to the characteristically protracted physiological effects of this peptide on the vasculature.
Mol Pharmacol 1990 Aug
PMID:Internalization of endothelin by cultured human vascular smooth muscle cells: characterization and physiological significance. 220 Sep 54

A series of tyrosinamidomethyl dihydrohaloisoxazole compounds, designed as mechanism-based inhibitors of bovine epidermal transglutaminase enzyme, was examined for effects on the formation of cross-linked envelopes by human SCC-9 malignant keratinocytes. Compounds inhibited ionophore-induced envelope formation in a manner that reflected their capacity to inhibit transglutaminase activity. Preincubation and inhibitor wash-out studies indicated that the inhibitor must be present at the time of cell activation by ionophore in order to inhibit envelope formation. The stereospecific nature of the inhibitory activity of these compounds on both transglutaminase activity and cross-linked envelope formation makes this class of compounds an important tool in the study of transglutaminase-mediated events at the cellular level.
Mol Pharmacol 1989 May
PMID:A new class of mechanism-based inhibitors of transglutaminase enzymes inhibits the formation of cross-linked envelopes by human malignant keratinocytes. 247 Oct 55

Calcium ions are crucial for expression of transglutaminase activity. Although lanthanides have been reported to substitute for calcium in a variety of protein functions, they did not replace the calcium requirement during transglutaminase activity measurements. Furthermore, lanthanides strongly inhibited purified liver transglutaminase activity using either casein or fibrinogen as substrates. Terbium (III) inhibition of transglutaminase-catalyzed putrescine incorporation into casein was not reversed by the presence of 10-200 fold molar excess of calcium ions (Ki for Tb(III) = 60 microM). Conformational changes in purified liver transglutaminase upon Tb(III) binding were evident from a biphasic effect of Tb(III) on transglutaminase binding to fibrin. Low concentrations of Tb(III) (1 microM to 10 microM) inhibited the binding of transglutaminase to fibrin, whereas higher concentrations (20 microM to 100 microM) promoted binding. Conformational changes in purified liver transglutaminase consequent to Tb(III) binding were also demonstrated by fluorescence spectroscopy due to Forster energy transfer. Fluorescence emission was stable to the presence of 200 mM NaCl and 100 mM CaCl2 only partially quenched emission. Purified liver transglutaminase strongly bound to Tb(III)-Chelating Sepharose beads and binding could not be disrupted by 100 mM CaCl2 solution. Our data suggest that Tb(III)-induced conformational changes in transglutaminase are responsible for the observed effects on enzyme structure and function. The potential applications of Tb(III)-transglutaminase interactions in elucidating the structure-function relationships of liver transglutaminase are discussed.
Mol Cell Biochem 1989 Jan 23
PMID:Consequences of terbium (III) binding on the conformation and enzymatic activity of guinea pig liver transglutaminase. 256 5

The effects of activators and inhibitors of protein kinase C (phorbol esters and H-7) and antagonist to calmodulin (TFP) on polyamine transport in murine leukemia (L1210) cells are investigated. Phorbol esters and H-7 are found to enhance and curtail the uptake of 14C-Spermidine (Spd) respectively in L1210 cells. TFP also inhibits the uptake process. After desialation of cells with neuraminidase, phorbol esters are found to further increase the uptake of 14C-Spd by 35% compared to untreated cells. The sialic acid contents of the cells are regenerated by incubation with 14C-glucosamine for 18 hours. The regenerated cells mimic like untreated cells for the uptake of 14C-Spd i.e. after regeneration of sialic acids, the Spd uptake is curtailed significantly in comparison with desialated cells. Phorbol esters are found to enhance the activity of transglutaminase present in L1210 cells while H-7 and TFP exhibit reverse effects. The possible role of phorbol esters, H-7 and TFP and their effects on transglutaminase activity in relation with Spd transport process are discussed.
Cell Mol Biol 1989
PMID:Role of protein kinase C activators and inhibitors, calmodulin antagonists and membrane sialic acids in polyamine transport in murine leukemia cells. 256 12


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