Kazunori Hirayoshi

Quercetin, a bioflavonoid, inhibits the increase of human multidrug resistance gene (MDR1) expression caused by arsenite

Expression of the MDR1 gene, which encodes P‐glycoprotein, is increased under some stress conditions. We have reported that quercetin, a bioflavonoid, inhibits the expression of heat‐shock proteins. We have identified the effects of quercetin on the MDR1 gene expression in the human hepatocarcinoma cells line, HepG2. The increase of P‐glycoprotein synthesis and MDR1 mRNA accumulation caused by exposure to arsenite were inhibited by quercetin. The CAT assay suggested that quercetin suppressed the transcriptional activation of the MDR1 gene after exposure to arsenite. Although many drugs that prevent the P‐glycoprotein function have been reported, this is the first report to describe the inhibition of MDR1 expression by a reagent.

Phosphorylation of the stress protein hsp27 is an early event in murine myelomonocytic leukemic cell differentiation induced by leukemia inhibitory factor/D-factor.

Leukemia inhibitory factor/D-factor, a potent differentiation-inducing glycoprotein for murine myelomonocytic leukemic M1 cells, rapidly stimulated the phosphorylation of a 27 kDa protein with an isoelectric point of 5.6 in a LIF-sensitive M1-T22 cell line but not in a LIF-resistant M1-D(-) cell line. The increase in phosphorylation was detectable 5 min after LIF treatment and was maximal at 10 min. Heat shock treatment at 44.5 degrees C for 30 min also induced the phosphorylation of the same 27 kDa protein. Although this 27 kDa protein did not become labeled with [35S]-methionine, metabolic labeling experiments using [35S]-cysteine or [3H]-leucine clearly demonstrated that the synthesis of this protein was enhanced after heat shock. These results suggest that the phosphorylated 27 kDa protein is a low molecular weight stress protein and that the protein may play a role at an early stage in the LIF signaling pathway probably linked to macrophagic differentiation.

Expression of a provirus of human T cell leukaemia virus type I by DNA transfection

We isolated the full length provirus of human T cell leukaemia virus type I (HTLV-I) from MT-2, a lymphoid cell line producing HTLV-I. In three non-lymphoid cell lines (COS7, human osteosarcoma HOS cells, and HeLa) this provirus expressed a trans-acting activity after co-transfection with a recombinant plasmid carrying a bacterial chloramphenicol acetyltransferase gene under the control of a long terminal repeat of HTLV-I provirus. The trans-acting protein p40 was detected by immunoprecipitation in transfected HOS cells. Structural proteins of HTLV-I, the gag and env products, were also formed and processed in the same manner as observed in MT-2 cells. In transfected HeLa cells, the p40 protein was mainly localized in the nucleus, while other structural proteins were detected in the cytoplasm and/or the membrane by indirect immunofluorescence. Syncytium formation was observed in HeLa cells after transfection. These results demonstrated that non-lymphoid cells could produce the major proteins of HTLV-I after DNA transfection of the cloned provirus.

The transformation-sensitive heat shock protein (HSP47) binds specifically to fetuin

The transformation-sensitive heat shock protein of Mr = 47,000 (hsp47) has been shown to bind to collagen and gelatin. We examined the binding specificity of hsp47. The binding of hsp47 to gelatin-Sepharose 4B was competitively inhibited by fetuin as effectively as by gelatin or collagen, whereas a variety of other proteins tested had no effect. Fetuin-coupled Sepharose 4B was found to bind hsp47 even at high ionic strength, but the complex was dissociated at pH less than or equal to 5.5.)

Expression of the c-myc gene in human gastrointestinal malignancies

We have examined the level of the c-myc transcript in 6 esophageal, 16 gastric, 19 colorectal and 1 anal cancer tissue samples; these included four lymph nodes and six hepatic metastases obtained surgically. The esophageal cancer tissues were without an increase of the c-myc transcript, some of the gastric cancer samples showed a two to three fold increase and most of the colorectal and the one anal cancer samples showed a two to ten fold increase when compared with a normal mucosal layer. Therefore, the level of the c-myc transcript in human gastrointestinal malignancies shows organ dependency. Local, lymphatic, and hepatic metastases showed little difference in the level of c-myc mRNA from that of the primary tumor.

Separate Cis-acting DNA Elements Control Cell Type- and Tissue-specific Expression of Collagen Binding Molecular Chaperone HSP47

HSP47 is a collagen-binding heat shock protein and is assumed to act as a molecular chaperone in the biosynthesis and secretion of procollagen. As the synthesis of HSP47 is closely correlated with that of collagen in various cell lines and tissues, we performed a promoter/reporter assay using HSP47-producing and nonproducing cells. 280 base pairs (bp(s)) of upstream promoter were shown to be necessary for the basal expression but not to be enough for the cell type-specific expression. When the first and the second introns were introduced downstream of this 280-bp region, marked up-regulation of the reporter activity was observed in HSP47-producing cells but not in nonproducing cells. This was confirmed in transgenic mice by staining the lacZ gene product under the control of the 280-bp upstream promoter and the introns. Staining was observed in skin, chondrocytes, precursor of bone, and other HSP47/collagen-producing tissues. A putative Sp1-binding site at −210 bp in the promoter, to which Sp3 and an unidentified protein bind, was shown to be responsible for this up-regulation when combined with the introns. However no difference in the binding to this probe was observed between HSP47-producing and nonproducing cells. The responsible region for cell type-specific up-regulation was found to be located in a 500-bp segment in the first intron. On electrophoresis mobility shift assay using this 500-bp probe, specific DNA-protein complexes were only observed in HSP47-producing cell extracts. These results suggest that two separate elements are necessary for the cell type-specific expression of the hsp47 gene; one is a putative Sp1-binding site at −210 bp necessary for basal expression, and the other is a 500-bp region within the first intron, required for cell type-specific expression.

Both D factor/LIF and IL-6 inhibit the differentation of mouse teratocarcinoma F9 cells

Differentation‐stimulating factor (D factor)/leukemia inhibitory factor (LIF) and IL‐6 are reported to be cytokines having multifaced functions including the induction of differentation in mouse myeloid leukemia MI cells. We here report that both D factor/LIF and IL‐6 inhibit the differentation of mouse teratocarcinoma F9 cells induced by retinoic acid alone or combined with dibutyryl cAMP. From the microscopic observation as well as Northern blot analysis using cDNA probes encoding several marker proteins for differentiation of F9 cells, we conclude that D factor/ LIF and IL‐6 are functionaly closely related in the induction of differentation in MI cells in the inhibition of F9 differentiation.

Effects of type-β1 transforming growth factor on the proliferation and differentiation of mouse myelomonocytic leukemia cells (M1)☆

Murine myelomonocytic leukemia M1 cells have been used to examine the effects of type-beta 1 transforming growth factor (TGF-beta 1) on cellular proliferation and differentiation in monocyte-macrophage lineage. TGF-beta 1 inhibited immature M1 cell growth due to a general slowdown of the cell cycle, without arrest at any specific point. Ten nanograms per milliliter TGF-beta 1 completely suppressed phagocytic activity and adhesion to the dish surface and partially inhibited the expression of Fc receptors and vimentin during the differentiation of M1 cells induced by IL-6. IL-6-induced declines in the expression of c-myc mRNA and in the accumulation of G0/G1 cells were also partially blocked by TGF-beta 1. When treated concurrently with IL-6 and TGF-beta 1, approximately 50% of M1 cells were morphologically converted to promonocyte or monocyte-like cells, which did not exhibit the characteristics of mature macrophages. Although pretreatment with TGF-beta 1 also inhibited the IL-6-induced phagocytic activity, this inhibition was reversible. Once TGF-beta 1 was removed from the culture medium after 72 h of incubation with IL-6, the kinetics of differentiation induced by IL-6 were faster in pretreated cells than in nonpretreated cells. TGF-beta 1 appears to inhibit the IL-6 induced conversion of M1 cells at the intermediate stage of monocytic differentiation.

Interaction of HSP47 with Newly Synthesized Procollagen, and Regulation of HSP Expression

We have found a novel stress (heat shock) protein whose molecular size is 47kDa. As hsp47 binds to collagen, it can be easily purified using gelatin-Sepharose. Indirect immunofluorescence and immunoelectron microscopic studies using polyclonal and monoclonal antibodies against HSP47 indicated the localization of HSP47 in the endoplasmic reticulum (ER) of the fibroblast. Immunoprecipitation studies using anti-HSP47 antibody revealed that two chains (α and s) of type I procollagen were co-precipitated with HSP47.

Perturbation of Discrete Sites on a Single Protein Domain with RNA Aptamers: Targeting of Different Sides of the TATA-Binding Protein (TBP)

Control of interactions among proteins is critical in the treatment of diseases, but the specificity required is not easily incorporated into small molecules. Macromolecules could be more suitable as antagonists in this situation, and RNA aptamers have become particularly promising. Here we describe a novel selection procedure for RNA aptamers against a protein that constitutes a single structural domain, the Drosophila TATA-binding protein (TBP). In addition to the conventional filter partitioning method with free TBP as target, we performed another experiment, in which the TATA-bound form of TBP was targeted. Aptamers generated by both selections were able to bind specifically to TBP, but the two groups showed characteristics which were clearly different in terms of their capability to compete with TATA-DNA, their effects on the TATA-bound form of TBP, and their effects on in vitro transcription. The method used to generate these two groups of aptamers can be used with other targets to direct aptamer specificity to discrete sites on the surface of a protein.