scholarly journals Changes in the expression of the human adenine nucleotide translocase isoforms condition cellular metabolic/proliferative status

Open Biology ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 150108 ◽  
Author(s):  
Aleix Gavaldà-Navarro ◽  
Teresa Mampel ◽  
Octavi Viñas

Human cells express four mitochondrial adenine nucleotide translocase (hANT) isoforms that are tissue-specific and developmentally regulated. hANT1 is mainly expressed in terminally differentiated muscle cells; hANT2 is growth-regulated and is upregulated in highly glycolytic and proliferative cells; and hANT3 is considered to be ubiquitous and non-specifically regulated. Here, we studied how the expression of hANT isoforms is regulated by proliferation and in response to metabolic stimuli, and examined the metabolic consequences of their silencing and overexpression. In HeLa and HepG2 cells, expression of hANT3 was upregulated by shifting metabolism towards oxidation or by slowed growth associated with contact inhibition or growth-factor deprivation, indicating that hANT3 expression is highly regulated. Under these conditions, changes in hANT2 mRNA expression were not observed in either HeLa or HepG2 cells, whereas in SGBS preadipocytes (which, unlike HeLa and HepG2 cells, are growth-arrest-sensitive cells), hANT2 mRNA levels decreased. Additionally, overexpression of hANT2 promoted cell growth and glycolysis, whereas silencing of hANT3 decreased cellular ATP levels, limited cell growth and induced a stress-like response. Thus, cancer cells require both hANT2 and hANT3, depending on their proliferation status: hANT2 when proliferation rates are high, and hANT3 when proliferation slows.

2018 ◽  
Vol 67 (2) ◽  
pp. 129-141 ◽  
Author(s):  
Munetaka Ozeki ◽  
Wulamujiang Aini ◽  
Aya Miyagawa-Hayashino ◽  
Keiji Tamaki

Summary Cholestasis is a condition wherein bile flow is interrupted and lithocholic acid is known to play a key role in causing severe liver injury. In this study, we performed in-depth analysis of the morphological changes in bile canaliculi and the biological role of villin in cholestasis using lithocholic acid-stimulated HepG2 human hepatocarcinoma cells. We confirmed disruption of the bile canaliculi in liver sections from a liver allograft patient with cholestasis. Lithocholic acid caused strong cytotoxicity in HepG2 cells, which was associated with abnormal morphology. Lithocholic acid reduced villin expression, which recovered in the presence of nuclear receptor agonists. Furthermore, villin mRNA expression increased following small interfering RNA (siRNA)-mediated knockdown of the nuclear farnesoid X receptor and pregnane X receptor. Villin knockdown using siRNA caused cell growth arrest in HepG2 cells. The effect of villin-knockdown on whole-genome expression in HepG2 cells was analyzed by DNA microarray. Our data suggest that lithocholic acid caused cell growth arrest by suppressing villin expression via farnesoid X receptor and pregnane X receptor in HepG2 cells.


2006 ◽  
Vol 36 (1) ◽  
pp. 9-21 ◽  
Author(s):  
Chun-Che Yen ◽  
Ya-Hui Huang ◽  
Chu-Yu Liao ◽  
Cheng-Jung Liao ◽  
Wan-Li Cheng ◽  
...  

Thyroid hormone (triiodothyronine, T3) regulates growth, development and differentiation. To examine the influence of T3 on hepatoma cell growth, thyroid receptor (TR)α1 or TRβ1 over-expressing HepG2 cell lines were used. Growth of the HepG2-TR stable cell line was inhibited by over 50% following treatment with T3. However, transforming growth factor (TGF)-β neutralizing antibody, but not the control antibody can reverse the cell growth inhibition effect of T3. Flow cytometric analysis indicated that the growth inhibition was apparent at the transition point between the G1 and S phases of the cell cycle. The expression of major cell cycle regulators was used to provide further evidence for the growth inhibition. Cyclin-dependent kinase 2 (cdk2) and cyclin E were down-regulated in HepG2-TR cells. Moreover, p21 protein or mRNA levels were up-regulated by around 5-fold or 7.3-fold respectively following T3 treatment. Furthermore, phospho-retinoblastoma (ppRb) protein was down-regulated by T3. The expression of TGF-β was studied to delineate the repression mechanism. TGF-β was stimulated by T3 and its promoter activity was enhanced six- to eight-fold by T3. Furthermore, both T3 and TGF-β repressed the expression of cdk2, cyclin E and ppRb. On the other hand, TGF-β neutralizing but not control antibody blocked the repression of cdk2, cyclin E and ppRb by T3. These results demonstrated that T3 might play a key role in liver tumor cell proliferation.


2013 ◽  
Vol 25 (1) ◽  
pp. 245
Author(s):  
N.-H. Kang ◽  
K.-C. Choi

Resveratrol (trans-3,4,5-trihydroxystilbene; RES) was adopted in this study as a novel phytoestrogen displaying antioxidant, antiinflammatory, and anticancer effects. In this study, we evaluated the inhibitory effect of RES on the cell growth induced by 17β-oestradiol (E2), a typical oestrogen, and bisphenol A (BPA), an endocrine-disrupting chemical (EDC) in BG-1 ovarian cancer cells expressing oestrogen receptors (ER) through down-regulating oestrogen receptor α (ERa) and insulin-like growth factor-1 receptor (IGF-1R). The EDC and oestrogen appear to promote the development of the oestrogen-dependent cancers. Thus, we need to develop therapeutic methods for EDC-dependent cancers. In in vitro experiments, we examined the cell viability and mRNA expression of ERa ± IGF-1R genes following the treatments with E2 or BPA in the presence or absence of RES or ICI 182 780, an ER antagonist, by MTT assay and RT-PCR, respectively. We also examined the protein level of ERa, phosphorylated insulin receptor substrate-1 (IRS-1), phosphorylated Akt1/2/3, p21, and cyclin D1 by Western blot analysis. Treatment with E2 or BPA remarkably increased the growth of BG-1 ovarian cancer cells, and their enhanced cell growth appeared to be mediated by ERa. In addition, the treatment of BG-1 ovarian cancer cells with E2 or BPA resulted in an increase in ERa and IGF-1R gene expressions. However, co-treatment of RES reversed E2- or BPA-induced ovarian cancer cell growth and mRNA expressions of ERa and IGF-1R. The protein levels of phosphorylated IRS-1 and Akt were upregulated by E2 or BPA, whereas these levels were downregulated by co-treatment of RES in the presence of E2 or BPA. Taken together, these results indicate that RES may effectively inhibit ovarian cancer cell growth via downregulating cross-talk between ERa and IGF-1R. This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Ministry of Education, Science and Technology (MEST) of Korea government (no. 2011-0015385).


2000 ◽  
Vol 278 (3) ◽  
pp. G384-G389 ◽  
Author(s):  
Ilaria Demori ◽  
Sara Balocco ◽  
Adriana Voci ◽  
Emilia Fugassa

The insulin-like growth factor (IGF) binding proteins (IGFBPs) are important regulators of cell growth produced by different tissues. The IGFBPs regulate cell growth by modulating the activity and bioavailability of IGFs. The evidence that IGFBP-1 is a liver-specific immediate-early gene highly induced after 70% partial hepatectomy (PHx) suggests a role for the IGF-IGFBP system in hepatic regeneration. In this work we analyzed the effect of PHx on the expression of IGFBP-4, which is highly produced by the liver and very abundant in rat serum. Our results show a marked increase in hepatic IGFBP-4 mRNA levels 6–12 h after PHx and no significant change in sham-operated control animals. A parallel rise in IGFBP-4 transcript abundance was observed in the kidneys of PHx rats but not in sham-operated animals. Moreover, ligand blot analysis demonstrated that serum IGFBP-4 levels began to increase 12–24 h after surgery, consistent with the rise in the corresponding mRNA. This enhancement in IGFBP-4 production after PHx could be part of a fine regulatory mechanism to modulate IGF activity during liver regeneration.


1995 ◽  
Vol 15 (3) ◽  
pp. 1244-1253 ◽  
Author(s):  
C Vaziri ◽  
D V Faller

Platelet-derived growth factor BB (PDGF-BB) is an important extracellular factor for regulating the G0-S phase transition of murine BALB/c-3T3 fibroblasts. We have investigated the expression of the PDGF beta receptor (PDGF beta R) in these cells. We show that the state of growth arrest in G0, resulting from serum deprivation, is associated with increased expression of the PDGF beta R. When the growth-arrested fibroblasts are stimulated to reenter the cell cycle by the mitogenic action of serum or certain specific combinations of growth factors, PDGF beta R mRNA levels and cell surface PDGF-BB-binding sites are markedly downregualted. Oncogene-transformed 3T3 cell lines, which fail to undergo growth arrest following prolonged serum deprivation, express constitutively low levels of the PDGF beta R mRNA and possess greatly reduced numbers of cell surface PDGF receptors, as determined by PDGF-BB binding and Western blotting (immunoblotting). Nuclear runoff assays indicate the mechanism of repression of PDGF beta R expression to be, at least in large part, transcriptional. These data indicate that expression of the PDGF beta R is regulated in a growth state-dependent manner in fibroblasts and suggest that this may provide a means by which cells can modulate their responsiveness to the actions of PDGF.


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