21 research outputs found
Hepatitis B virus X protein and the estrogen receptor variant lacking exon 5 inhibit estrogen receptor signaling in hepatoma cells
Hepatitis B virus (HBV) X protein (HBx) is considered to play a role in the development of hepatocellular carcinoma (HCC) during HBV infection. HCC was shown to be more prevalent in men than in women. Estrogen, which exerts its biological function through estrogen receptor (ER), can inhibit HBV replication. ERΔ5, an ERα variant lacking exon 5, was found to be preferentially expressed in patients with HCC compared with patients with normal livers. Here, we report the biological role of ERΔ5 and a novel link between HBx and ERα signaling in hepatoma cells. ERΔ5 interacts with ERα in vitro and in vivo and functions as a dominant negative receptor. Both ERα and ERΔ5 associate with HBx. HBx decreases ERα-dependent transcriptional activity, and HBx and ERΔ5 have additive effect on suppression of ERα transactivation. The HBx deletion mutant that lacks the ERα-binding site abolishes the HBx repression of ERα. HBx, ERα and histone deacetylase 1 (HDAC1) form a ternary complex. Trichostatin A, a specific inhibitor of HDAC enzyme, can restore the transcriptional activity of ERα inhibited by HBx. Our data suggest that HBx and ERΔ5 may play a negative role in ERα signaling and that ERα agonists may be developed for HCC therapy
Suppression of Estrogen Receptor Transcriptional Activity by Connective Tissue Growth Factor
Secreted growth factors have been shown to stimulate the transcriptional activity of estrogen receptors (ER) that are responsible for many biological processes. However, whether these growth factors physically interact with ER remains unclear. Here, we show for the first time that connective tissue growth factor (CTGF) physically and functionally associates with ER. CTGF interacted with ER both in vitro and in vivo. CTGF interacted with ER DNA-binding domain. ER interaction region in CTGF was mapped to the thrombospondin type I repeat, a cell attachment motif. Overexpression of CTGF inhibited ER transcriptional activity as well as the expression of estrogen-responsive genes, including pS2 and cathepsin D. Reduction of endogenous CTGF with CTGF small interfering RNA enhanced ER transcriptional activity. The interaction between CTGF and ER is required for the repression of estrogen-responsive transcription by CTGF. Moreover, CTGF reduced ER protein expression, whereas the CTGF mutant that did not repress ER transcriptional activity also did not alter ER protein levels. The results suggested the transcriptional regulation of estrogen signaling through interaction between CTGF and ER, and thus may provide a novel mechanism by which cross-talk between secreted growth factor and ER signaling pathways occurs
Investigation of Free Fatty Acid Associated Recombinant Membrane Receptor Protein Expression in HEK293 Cells Using Raman Spectroscopy, Calcium Imaging, and Atomic Force Microscopy
G-protein-coupled receptor 120 (GPR120) is a previously
orphaned
G-protein-coupled receptor that apparently functions as a sensor for
dietary fat in the gustatory and digestive systems. In this study,
a cDNA sequence encoding a doxycycline (Dox)-inducible mature peptide
of GPR120 was inserted into an expression vector and transfected in
HEK293 cells. We measured Raman spectra of single HEK293 cells as
well as GPR120-expressing HEK293–GPR120 cells at a 48 h period
following the additions of Dox at several concentrations. We found
that the spectral intensity of HEK293–GPR120 cells is dependent
upon the dose of Dox, which correlates with the accumulation of GPR120
protein in the cells. However, the amount of the fatty acid activated
changes in intracellular calcium (Ca<sup>2+</sup>) as measured by
ratiometric calcium imaging was not correlated with Dox concentration.
Principal components analysis (PCA) of Raman spectra reveals that
the spectra from different treatments of HEK293–GPR120 cells
form distinct, completely separated clusters with the receiver operating
characteristic (ROC) area of 1, while those spectra for the HEK293
cells form small overlap clusters with the ROC area of 0.836. It was
also found that expression of GPR120 altered the physiochemical and
biomechanical properties of the parental cell membrane surface, which
was quantitated by atomic force microscopy (AFM). These findings demonstrate
that the combination of Raman spectroscopy, calcium imaging, and AFM
may provide new tools in noninvasive and quantitative monitoring of
membrane receptor expression induced alterations in the biophysical
and signaling properties of single living cells
Incidence of a brain structural abnormities (CT, NMR) in patients with affective disorder
Currently we are experiencing a boom imaging methods. We are constantly improving their accessibility, their distinctive abilities and the possibility of using both in research and in clinical practice. They penetrate well into psychiatry, where he tries as well as in other fields to shed light etiology of diseases contribute to their diagnosis and treatment. The cost of are large, the cost of execution of each test is different, can Thus burden on public budgets in different ways, so it is necessary to were determined and the proper indications. What is the significance of these methods in determine the incidence of brain structural abnormalities in patients with affective disorder and the implications of the findings for these abnormalities alone patients, the aim of the present study