Roles of naofen, a novel WD-repeat-2 protein, in the CCl4-treated livers--a possible relationship to cell proliferation

MicroRNA-183 accelerates the proliferation of hepatocyte during liver regeneration through targeting programmed cell death protein 6

BACKGROUND

Liver regeneration is a highly orchestrated process concerning the modulation of various microRNAs (miRs). miR-183 was recently found to be involved in the process of liver regeneration, that miR-183 was remarkably up-regulated at 2-6 h after partial hepatectomy.

OBJECTIVE

This study was aimed to explore the mechanism of miR-183 in on liver regeneration.

METHODS

After partial hepatectomy (PH) or transfection, we measured the changes of miR-183 and programmed cell death protein 6 (PDCD6) levels in rats and the hepatocytes. The histopathology was observed with hematoxylin-eosin staining. The miR-183 mimic and inhibitor plasmids were intravenously injected into rats, and the liver weight/body weight ratio was calculated. The prediction of TargetScan and the validation of luciferase activity assay were employed to confirm the targeting relationship between miR-183 and PDCD6. The viability, apoptosis and cell cycle of transfected rat hepatocyte BRL-3A were determined via MTT and flow cytometry assays.

RESULTS

MiR-183 expression showed a contrary tendency with that of PDCD6 during liver regeneration. Enhanced miR-183 in rats could notably increase liver/body weight ratio, while its inhibition did conversely. Overexpressed PDCD6, a target of miR-183, repressed the viability and cell cycle in hepatocytes, whereas its silence led to contrary results. Overexpressed miR-183 in BRL-3A cells enhanced cell viability and promoted the cell cycle yet suppressed apoptosis, whereas its inhibition showed contrary results, which were offset by PDCD6.

CONCLUSIONS

Collectively, miR-183 promoted liver regeneration via targeting PDCD6.

MicroRNA-34a regulates liver regeneration and the development of liver cancer in rats by targeting Notch signaling pathway

OBJECTIVE

This study aimed to investigate the role of microRNA-34a (miR-34a) in regulating liver regeneration (LR) and the development of liver cancer in rats by targeting Notch signaling pathway.

METHODS

Thirty male Sprague-Dawley (SD) rats were randomly assigned into partial hepatectomy (PH) group and sham hepatectomy (SH) group. Hematoxylin and eosin (HE) staining was used to observe the histological change in liver tissues. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) levels. Dual-luciferase reporter gene assay was performed to examine whether miR-34a targeted Notch1 gene. Human liver cancer Huh7 cells were transfected and divided into blank, negative control (NC), miR-34a mimics and miR-34a inhibitors groups. MTT and flow cytometry were used to detect cell growth, and cell cycle and apoptosis, respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied detect to the expressions of miR-34a and Notch receptor mRNA. Western blotting was performed to detect the protein expressions of Notch receptors, P21, Bax, Bcl-2 and Bcl-xL. Tumor xenograft in nude mice was done to observe tumor formation in different groups.

RESULTS

Compared to the SH group, miR-34a expression in liver tissues in the PH group decreased first and then increased to the normal level during LR. In early stage of LR, the expressions of Notch receptors and miR-34a were negatively correlated. Compared to the blank and NC groups, the cell growth was inhibited, cell cycle was mainly arrested in the G2/M phase and cell apoptosis rate increased in the miR-34a mimics group. Moreover, the expressions of miR-34a, P21 and Bax were up-regulated, while the expressions of Notch receptors, and Bcl-2 and Bcl-xL were down-regulated in this group. Additionally, the tumor growth in the miR-34a mimics group was reduced. The miR-34a inhibitors group showed contrary tendencies.

CONCLUSION

Our study demonstrates that miR-34a regulated LR and the development of liver cancer by inhibiting Notch signaling pathway.

Age-related brain expression and regulation of the chemokine CCL4/MIP-1β in APP/PS1 double-transgenic mice

The detrimental effect of activation of the chemokine CCL4/MIP-1β on neuronal integrity in patients with HIV-associated dementia has directed attention to the potential role of CCL4 expression and regulation in Alzheimer disease. Here, we show that CCL4 mRNA and protein are overexpressed in the brains of APPswe/PS1ΔE9 (APP/PS1) double-transgenic mice, a model of cerebral amyloid deposition; expression was minimal in brains from nontransgenic littermates or single-mutant controls. Increased levels of CCL4 mRNA and protein directly correlated with the age-related progression of cerebral amyloid-β (Aβ) levels in APP/PS1 mice. We also found significantly increased expression of activating transcription factor 3 (ATF3), which was positively correlated with age-related Aβ deposition and CCL4 in the brains of APP/PS1 mice. Results from chromatin immunoprecipitation-quantitative polymerase chain reaction confirmed that ATF3 binds to the promoter region of the CCL4 gene, consistent with a potential role in regulating CCL4 transcription. Finally, elevated ATF3 mRNA expression in APP/PS1 brains was associated with hypomethylation of the ATF3 gene promoter region. These observations prompt the testable hypothesis for future study that CCL4 overexpression, regulated in part by hypomethylation of the ATF3 gene, may contribute to neuropathologic progression associated with amyloid deposition in Alzheimer disease.

Effects of 1-O-hexyl-2,3,5-trimethylhydroquinone on carbon tetrachloride-induced hepatic cirrhosis in rats

AIM

The present study was undertaken to evaluate the effects of 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), a synthesized vitamin E derivative, on carbon tetrachloride (CCl(4))-induced cirrhosis.

METHODS

Rats were treated with hypodermic injections of CCl(4) twice a week to induce the hepatic cirrhosis, and given drinking water containing HTHQ or solvent. Primary cultures of rat hepatocytes were performed to evaluate the effects of HTHQ on the expression of inducible nitric oxide synthase (iNOS).

RESULTS

Masson's staining of rat livers showed fibrosis around pseudo-lobules in the CCl(4) group, the lesions being reduced in the CCl(4) HTHQ group. Increases in liver tissue hydroxyproline and alpha(1)(I) collagen, alpha-smooth muscle actin and iNOS induced by CCl(4), were also markedly diminished by HTHQ. Furthermore, both HTHQ and vitamin E attenuated interleukin-1beta-induced iNOS protein expression in cultured hepatocytes, the potency of HTHQ being 10-times higher than that of vitamin E.

CONCLUSION

HTHQ may inhibit development of hepatic cirrhosis in rats, more potently than vitamin E, by inhibiting the iNOS expression in hepatocytes. Because vitamin E has a radical scavenging action, roles of NO and peroxynitrite will be discussed in the effects of HTHQ on the fibrosis.

Role of naofen, a novel WD repeat-containing protein, in reducing nitric oxide-induced relaxation

1. Naofen, a novel WD40 repeat domain-containing protein, has recently been found in the intracellular compartment. The aim of the present study was to determine whether naofen affects thoracic aortic vascular reactivity in normotensive and hypertensive rats and whether naofen is present in the thoracic aorta. In addition, we examined whether naofen modulates acetylcholine (ACh)-stimulated nitric oxide (NO) release from the endothelium. 2. Immunohistochemistry showed greater naofen expression in endothelial cells in the DOCA-salt group compared with controls. There was increased naofen mRNA expression in deoxycorticosterone acetate (DOCA)-salt hypertensive rats compared with normotensive rats. 3. Acetylcholine-induced relaxation of rat aortic strips was decreased in DOCA-salt hypertensive rats compared with normotensive rats. Naofen-N- but not naofen-C-terminal protein caused a significant decrease in ACh-induced relaxation of aortic strips from normotensive rats. 4. Using a nitrite assay in a murine aortic endothelial cell line demonstrated that naofen-N-terminal protein, but not naofen-C-terminal protein, significantly reduced ACh-induced NO production, suggesting that naofen interferes with NO production. 5. Administration of naofen-N-terminal protein, but not naofen-C-terminal protein, significantly inhibited cyclohydrolase (GCH) I mRNA expression in a murine aortic endothelial cell line, suggesting that naofen-N-terminal protein interferes with NO synthesis by inhibiting GCH I mRNA expression. 6. The results of the present study suggest that naofen is present in vascular endothelial cells and has an inhibitory effect on ACh-induced relaxation under normotensive conditions. The findings reinforce the functional significance of naofen-N-terminal protein on rat vascular reactivity.