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Vitamin C Promoted Liver Regeneration Following Partial Hepatectomy-induced Hepatic Injury in Senescence Marker Protein-30-deficient Mice
Vitamin C Promoted Liver Regeneration Following Partial Hepatectomy-induced Hepatic Injury in Senescence Marker Protein-30-deficient Mice
Journal of Life Science. 2015. Mar, 25(3): 336-344
Copyright © 2015, Korean Society of Life Science
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
  • Received : December 16, 2014
  • Published : March 30, 2015
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About the Authors
선영 한
미열 황
아영 김
은미 이
은주 이
명미 이
수은 성
상협 김
규식 정
jeongks@knu.ac.kr

Abstract
The capacity for liver regeneration involves a variety of nutritional factors. Vitamin C has multiple metabolic and antioxidant functions. In this study, we investigated the role of vitamin C in liver regeneration following hepatectomy in senescence marker protein (SMP)-30 knockout (KO) mice. Partial hepatectomy was performed by resecting the median and left lateral lobes of mice. Vitamin C accelerated liver recovery in SMP30 KO mice treated with vitamin C (KV). The livers of the KV mice exhibited lower levels of aspartate aminotransferase and lower injury than those of the KO mice. Increased type II transforming growth factor-β receptor (TGF-βRII)-mediated regeneration signaling was accompanied by HGF and cMet in the KV but not the KO mice. Consistent with this, the expression of cell cycle regulatory proteins, including cyclin D1 and proliferating cell nuclear antigen (PCNA), increased rapidly in the KV mice. Enhanced activation of ERK and GSK-3β proteins and a significantly increased number of binuclear hepatocytes were also detected in the livers of the KV mice. Moreover, the KV mice synthesized the highest levels of albumin. These data suggest that treating SMP30 knockout mice with vitamin C resulted in earlier recovery and liver regeneration by activation of the regeneration system.
Keywords
Introduction
The liver has a remarkable capacity to regenerate. Although hepatocytes rarely divide under normal conditions, they proliferate rapidly in response to the loss of liver mass caused by surgical removal, chemical injury, or viral infection [11 , 21 , 36] . Liver regeneration is a well-orchestrated process in which complex signaling pathways coordinate the progression of hepatocytes through three distinct stages: withdrawal from quiescence (“priming phase”), cell cycle entry and progression, and the cessation of cell division with a return to quiescence [11] . The cell cycle entry and progression phase occurs in two steps. After the priming phase, hepatocytes enter the G 1 phase of cell cycle and activate immediate early genes (IEGs) such as c- fos and c- jun . Activation of IEGs results in the expression of cell cycle regulatory genes including G 1 cyclin and cyclin D [4 , 9 , 29] . The induction of cyclin D1 is the most reliable marker of cell cycle progression (G1 phase) in hepatocytes, as demonstrated both in vivo and in vitro [1] . In the second step, hepatocytes leave G1 and enter S phase, which is accompanied by the phosphorylation of retinoblastoma protein (pRb) and the upregulated expression of a number of genes including cyclin E, cyclin A, and DNA polymerase [9 , 10 , 32] . In addition, the expression of the nuclear protein proliferating cell nuclear antigen (PCNA) is maximally elevated in the S phase of proliferating cells, which has been used as a marker of liver regeneration after partial hepatectomy (PHx, the removal of approximately 70% of the liver) in rats [17] .
Cell cycle progression is driven by growth factors including hepatocyte growth factor (HGF), epidermal growth factor (EGF), and transforming growth factor-α (TGF-α). Hepatocyte growth factor (HGF) has been known to play major roles in embryonic organ development, wound healing, and adult organ regeneration [24] . Specifically, previous studies suggested that HGF is a potent mitogen in mature hepatocytes, and acts as a hepatotropic factor during liver regeneration. These growth factors activate various mitogenic signaling cascades, including the mitogen-activated protein kinase (MEK)/extracellular signal regulated kinase 1/2 (ERK1/2) and phosphatidylinositol3-kinase (PI3K)/Akt pathways [6 , 23 , 36] . ERK1/2, which is a member of the mitogen-activated protein kinase (MAPK) family, phosphorylates several downstream substrates involved in cell growth and cell cycle control [19 , 35] . GSK3β is downstream of PI3K/Akt kinase, and is a ubiquitously expressed multifunctional serine/threonine protein kinase. It was originally identified as a key regulator of insulin-dependent glycogen synthesis, and has also been shown to support cell proliferation and liver regeneration [8 , 14 , 31 , 38] .
Senescence marker protein (SMP) 30 was first identified in 1992; it is mainly expressed in hepatocytes and the proximal tubular cells of kidneys, and its expression decreases with age [12]. Its expression is maintained at a high level throughout the tissue maturation process, and then decreases in an androgen-independent manner during the senescent stages [13] . Interestingly, SMP30 knockout (KO) mice developed symptoms of scurvy and aging when fed a vitamin C-free diet [26] . Vitamin C (ascorbic acid) is a nutrient that is required for a variety of biological functions. Humans, primates, and other animals such as guinea pigs depend on their diet as a source of vitamin C to prevent scurvy (the disease of vitamin C deficiency) and to maintain general health. Vitamin C can also function as a source of the signaling molecule hydrogen peroxide and as a Michael donor to form covalent adducts with endogenous electrophiles in plants [37] . There is considerable evidence reporting roles of vitamin C in inhibiting the proliferation, migration, and constriction of fibroblasts and lens epithelial cells [5] . Vitamin C is also required for some step(s) of G 1 and G 2 , prior to the onset of DNA replication and the G 2 mitosis transition, respectively [2 , 20 , 27] .
In this study, we investigated the effect of vitamin C on hepatectomy-induced liver regeneration in SMP 30 KO mice.
Materials and Methods
- Animal experiments
SMP30 KO mice were kindly provided by Dr. Akihito Ishigami, Tokyo Metropolitan Institute of Gerontology (Tokyo, Japan) [16] . The SMP30 KO and WT mice were housed in a room at 22±3℃, relative humidity of 50±10%, and a 12 hr light-dark cycle, and were given food and water ad libitum . Mice were intraperitoneally injected with 1 ml/kg of body weight CCl 4 in olive oil vehicle. One day after CCl4 injection, 70% PHx was performed by resecting the median and left lateral lobes of the liver in 8-week-old SMP30 KO mice and WT mice (C57BL/6 background) according to the method described by Higgins and Andersen [36] . Mice were divided into three groups: group 1 contained WT mice (WT), group 2 was vitamin C-treated SMP30 knockout (KV) mice, and group 3 was control untreated SMP30 knockout (KO) mice. Five mice from each group were sacrificed at 0, 24, 48, 72, and 120 hr after PHx. Liver remnants were then removed, weighed, and either snap-frozen in liquid nitrogen or processed for histology. The WT and KO groups were fed a vitamin C-free diet, whereas the KV group mice were given 5 ml of vitamin C water containing 1.5 g/l of vitamin C. Animal procedures were performed in accordance with the National Institutes of Health (NIH, Bethesda, USA) guidelines for the care and use of laboratory animals and approved by the Kyungpook National University Institutional Animal Care for the care and use of laboratory animals [Approval No. : KNU 2011-11].
- Liver regeneration ratio
The regeneration ratio (R) was calculated from the wet weight of the resected livers at PHx and the remnant livers at sacrifice. The regeneration ratio was calculating as the following: R (%) = 100×0.7× (W2/W1) [39] , where W1 is the weight of the liver resected during PHx, and W2 is the weight of the regenerating liver at sacrifice.
- Biochemical measurements
All serum samples were collected and stored at -70℃ prior to analysis. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured using standard enzymatic procedures (Hitachi, Tokyo, Japan). In addition, serum vitamin C levels were measured using a high performance liquid chromatography (HPLC)-electrochemical detection method [18] . Briefly, 100 μl of serum collected from the blood of mice by centrifugation at 3,000× g for 15 min was mixed with 450 μl of 3% metaphosphoric acid. After centrifugation at 10,000× g for 10 min, the supernatant was collected and the serum vitamin C levels were measured by HPLC using an Atlantis dC18 5 μm column (4.6×150 mm, Nihon Water, Tokyo, Japan). The mobile phase consisted of 50 mM phosphate buffer (pH 2.8), 0.2 g/l EDTA, and 2% methanol at flow rate of 1.3 ml/min. Electrical signals were recorded using an electrochemical detector with a glassy carbon electrode at +0.6 V.
- Liver histopathology and immunohistochemistry
Liver tissues were fixed in 10% buffered formalin, processed routinely, and embedded in paraffin. Sections 4-μm in thickness were cut, deparaffinized in xylene and toluene, and then rehydrated in a graded alcohol series. The sections were stained with hematoxylin and eosin (H&E) for histological examination. Immunohistochemistry was performed using primary antibodies against PCNA (Santa Cruz Biotechnology, Santa Cruz, CA, USA). Slides were incubated in 3% hydrogen peroxide in methanol for 30 min, and then microwaved at 750 W for 10 min in 0.01M citric buffer for antigen retrieval. The antigen-antibody complexes were visualized using an avidin-biotin-peroxidase complex solution with a VECTASTAIN ABC kit (Vector Laboratories, Burlingame, CA, USA) with 3,3-diaminobenzidine (Zymed Laboratories, San Francisco, CA, USA).
- Reverse transcriptase-polymerase chain reaction (RT-PCR)
Total RNA was isolated from frozen mouse livers using TRIzol (Invitrogen, Carlsbad, CA, USA). Total RNA was used as the template for reverse transcribing RNA into cDNA using AccuPower RT/PCR PreMix (Bioneer Corporation, Daejeon, Korea). The following primers were used: TGF-β RII, 5‘-TTCGCCGAGGTCTACAAG-3’ and 5‘-CTCTTGAGGT CCCTGTGAA-3’; HGF, 5‘-CTGGGGCTACACTGGATTG-3’ and 5‘-GATGCTTCAAACACACTGGC-3’; cMet, 5‘-TCACTCTTGGGAATCTGCCTGA- 3’ and 5‘-GCAACAGAGAAGGATATGG-AGC-3’; GSK-3β, 5‘-ATGGTCTGCAGGCTGTGTGT- 3’ and 5‘-TGTGCCTTGATTTGAGGGAA-3’; and GAPDH, 5‘-ACTCACGGCAAATTCAACGG-3’ and 5‘-ACCAGTGGATGCAGGGATGA-3’. The PCR products were visualized using 1.5% agarose gel electrophoresis.
- Immunoblotting
Snap-frozen liver tissues were homogenized in radioimmunoprecipitation assay buffer containing 1 mM Na 3 VO 4 , 50 mM NaF, and protease inhibitor cocktail tablets (Roche, Basel, Swiss). The lysates were centrifuged at 3,000 rpm for 10 min at 4℃ to remove solid tissues and debris. Subsequently, the supernatants were centrifuged at 14,000 rpm for 20 min at 4℃ to obtain soluble cytosolic proteins. The protein concentrations were then determined using the Bradford method. Protein samples were separated by 10-12% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). For immunoblotting, proteins were electrotransferred onto PVDF membranes (Schleicher & Schuell, Dassel, Germany) and blocked with 3% bovine serum albumin in Tris-buffered saline (TBS). The following antibodies were used for immunoblotting: anti-ERK (dilution 1:200), anti-p-ERK (1:1,000), anti-PCNA (1:500), anti-cyclin D1 (1:800, all from Santa Cruz Biotechnology, Santa Cruz, CA, USA), and anti-GAPDH (1:1,000, Cell Signaling Technology, Danvers, MA, USA). The primary antibodies were detected using horseradish peroxidase (HRP)-conjugated anti-mouse and anti-rabbit secondary IgG. Specific binding was then detected using the Super Signal West Dura Extended Duration Substrate (Pierce, Rockford, IL, USA) and exposure to medical X-ray film (Kodak, Tokyo, Japan). The band intensities were quantified using Image J software (NIH).
- Statistical analysis
All data are expressed as means ± standard errors (SEMs). The statistical significance between experimental groups was determined using Student’s t -test or one-way analysis of variance (ANOVA). A p -value of <0.05 was considered to indicate statistical significance. All statistical analyses were performed using the SPSS 19 statistical software program.
Results
- Vitamin C increased the liver regeneration ratio
To examine the effects of vitamin C on restoration of liver mass, the weight of the livers was measured at each time point after PHx. The liver regeneration ratios were calculated as described previously. As shown in Fig. 1 , the liver regeneration ratio was increased gradually in the KV group compared with KO, suggesting that treatment with vitamin C stimulated liver regeneration.
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The ratio of liver regeneration. R (%) = 100×0.7× (W2/W1), where W1 is the weight of the liver resected during the operation, and W2 is the weight of the regenerating liver. Significantly increased liver regeneration was observed in the KV group. Each value is presented as the mean ± SEM. *p<0.05, 0 vs. 120 hr of WT; #p<0.05, 0 vs. 120 hr of KV.
- Effect of vitamin C on biochemical changes during liver regeneration
Because serum ALT levels reflect the severity of liver damage, ALT levels are commonly used as a specific indicator of liver necrosis [25] . The KV and KO groups exhibited higher ALT levels than did the WT ( Fig. 2A ). There were no significant differences in ALT levels between the KV and KO groups. By contrast, AST levels in the KO group were significantly higher than those in the KV and WT groups were ( Fig. 2B ). Next, we measured the serum vitamin C levels. As shown in Fig. 2C , decreased serum vitamin C levels were observed in not only the WT group, but also in the KV group after liver damage. However, normal serum vitamin C levels were restored in the WT group 120 hr after PHx. The serum vitamin C levels decreased at the initial stages of liver regeneration, but then increased by 120 hr when complete liver regeneration was achieved in the KV and WT groups. In contrast, serum vitamin C levels were undetectable throughout the study in KO mice ( Fig. 2C ). These data suggest that vitamin C could be used to promote liver regeneration after liver damage.
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Serum measurements of ALT, AST, and vitamin C. There were no significant changes in ALT (A) and AST (B) in the KO group. However, the levels were lower in the KV group than those in the KO group were. (C) The serum levels of vitamin C decreased during liver regeneration. Each value is presented as the mean ± SEM. *p<0.05, KV vs. KO.
- Effect of vitamin C on the protein levels of growth factors
HGF/SF-Met and TGF-β/TGF-βRII (type II transforming growth factor-β receptor) mediate hepatocyte proliferation after PHx by activating several signaling pathways [22 , 33] . The levels of these growth factors increase during the early stages of liver regeneration, and decrease after complete liver regeneration. We examined the protein levels of these growth factors using immunoblotting. Fig. 3 reveals that the expression of TGF-β and TGF-βRII increased gradually up to 48 hr after PHx, decreased at 72 hr, and was barely detectable at 120 hr in WT and KV groups. In contrast, increased levels of both proteins were detected 120 hr after PHx in the KO group ( Fig. 3 ).
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TGF-β, TGF-β-receptor II, and growth factor expression in the regenerating liver. (A) The growth factor levels were increased in the early stages of liver regeneration, and decreased in complete liver regeneration. However, the expression was lower in the KO group than in other groups. Expression was upregulated in all groups from 24-72 hr, and then downregulated at 120 hr. The expression patterns were similar in the KV and WT groups. (B) The relative band densities were normalized to GAPDH. Each value is presented as the mean ± SEM. *p<0.05, KV vs. KO.
- Effect of vitamin C on the levels of proliferationrelated signaling proteins
Several studies have provided evidence for the essential role of the ERK pathway in proliferating hepatocytes [41] . These kinases phosphorylate a number of substrates and mediate the induction of several genes including c- fos and cyclin D1; this subsequently leads to cell cycle progression and growth in hepatocytes [35] . To investigate the effects of vitamin C on ERK activation, the phosphorylation of ERK was measured by immunoblotting. Vitamin C treatment led to the early activation of ERK in the KV and WT groups at 24 hr; in contrast, activation was only detected at 48 hr in the KO group ( Fig. 4 ). Next, we examined the protein levels of cyclin D1 and PCNA. Cyclin D1 was first detected 24 hr after PHx in the WT and KV groups. However, it was only detected at 48 hr in KO mice ( Fig. 5 ). The levels of PCNA protein increased during liver regeneration from 24-72 hr in all groups. However, levels were significantly higher in the KV group than those in the KO group were at 48 hr ( Fig. 6 ).
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The activation of ERK during liver regeneration. (A) Immunoblotting for ERK and p-ERK. (B) The relative band densities were normalized to GAPDH. Each value is presented as the mean ± SEM. *p<0.05, KV vs. KO.
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Alteration in cyclin D1 protein levels during liver regeneration. (A) Immunoblotting for cyclin D1. (B) The relative band densities were normalized to GAPDH. Each value is presented as the mean ± SEM. **p<0.05, KV vs. KO.
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Alteration in PCNA protein levels during liver regeneration. (A) Immunohistochemistry for PCNA (original magnification ×200). PCNA-positive hepatocytes were counted in five fields (×400) of each sample. (B) Immunoblotting for PCNA. (C) The relative band densities were normalized to GAPDH. Each value is presented as the mean ± SEM. *p<0.05, KV vs. KO.
- Effect of vitamin C on hepatic necrosis
Livers were harvested, and then stained with H&E. Widespread centrilobular necrosis and recruited inflammatory cells were observed when sections were analyzed microscopically ( Fig. 7 ). Severe necrosis was observed immediately following CCl 4 treatment, but then decreased during liver regeneration. In the KO group, necrosis was detected across a larger area than in the WT and KV groups. Gross findings revealed that the proliferation rate of inflammatory cells was faster at 48 and 72 hr than at other times. At the end of regeneration, the hepatic cord was rearranged and inflammatory cells had disappeared. Although inflammatory cells were not detected in significant numbers at 72 hr in the WT and KV groups, they were still observed until 120 hr in the KO group. These data suggest that liver regeneration occurred more slowly in vitamin C-deficient mice; these mice were also more susceptible to CCl 4 –induced injury than mice supplemented with vitamin C.
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Histological features during liver regeneration. (A) Histological image of a liver after H&E staining. CCl4-treated groups exhibited widespread centrilobular necrosis. Original magnification ×100; (B) ×200.
Discussion
The major finding of this study is that vitamin C promotes liver regeneration in vitamin C-deficient mice by upregulating growth factors and genes related to cell proliferation. We also identified the involvement of vitamin C in the hepatic regenerative response on the first day after PHx. Vitamin C-treated KO mice showed higher liver regeneration ratio than did water-treated KO mice. This enhanced regeneration was associated with increased DNA synthesis and cell cycle progression stimulated by the activation of TGF-β, TGF-βRII, HGF, c-met, and cyclin D1 in response to PHx.
TGF-β is member of a superfamily of growth and differentiation factors that interact with an equally diverse group of cell surface receptors [3] . TGF-β can regulate cell proliferation during both embryogenesis and liver regeneration [7 , 15] . Consistent with this, increased TGF-β mRNA expression was detected in hepatocytes after PHx and during liver regeneration [33] . In addition, the expression of TGF-β RII was restored to normal levels in the later stages of regeneration [34] . In the current study, the expression of TGF-β was increased during the early stages of liver regeneration, and then decreased when liver regeneration was complete in the WT and KV groups. However, levels in the KO group were lower than in either KV or WT mice. In addition, the levels of TGF-βRII were decreased to a lesser extent in KO than in the WT and KV groups.
We investigated the mechanism by which vitamin C regulates cell proliferation in the liver by assessing key signaling pathways that play roles in cell cycle progression. ERK and Akt both transmit mitogenic signals via the Ras pathway, and they are activated by phosphorylation in the regenerating liver in response to growth factors [6] . In this study, ERK was phosphorylated more rapidly and robustly in the KV group than in the KO group, suggesting that vitamin C could modulate hepatocyte replication by interacting with ERK signaling pathways. Interestingly, HGF and c-met levels were upregulated early after PHx in the KV group, but remained low in the KO group. In addition, p-ERK was activated 24 h after PHx in the KV group. The upregulation of growth factors might activate specific signaling cascades, and thus partially contribute to enhancing proliferative signals in the KV group. The signaling cascades activated by ERK have been implicated in controlling a diverse range of cell cycle proteins. Activated ERK translocates to the nucleus and induces the expression of, or activates, transcription factors including c- fos and c- jun , which in turn increase the transcription of genes involved in cell cycle progression such as cyclin D1 [28 , 30 , 40] . In the present study, the depletion of vitamin C altered the expression of cell cycle regulators following PHx, which was accompanied by rapid and robust ERK phosphorylation. These results provide a molecular link between increased levels of p-ERK and enhanced cell cycle progression in hepatocytes from the KV group.
Compared with the KO group, the remaining livers of the KV group showed a significant increase in weight 48 hr after PHx, which was due to increased cell proliferation. Because G 0 -M phase cells can be recognized by PCNA immunohistochemical staining in the liver, we performed immunoblotting and immunohistochemistry with PCNA antibodies to detect proliferating cells; the expression levels of PCNA correlated with the pattern of cell proliferation [35] . The KV group exhibited the highest expression of PCNA, whereas the KO group showed relatively reduced expression. This is consistent with the levels of cyclin D1, which is required for the G 1 /S transition; levels were also increased significantly in the KV group following PHx. Therefore, liver recovery was faster in the KV group than in KO as a consequence of the increased hepatocyte proliferation.
H&E staining revealed that the presence of inflammatory cells was sustained in the KO group compared with KV. This suggests that vitamin C depletion delayed liver regeneration. In addition, the vitamin C-treated group showed higher albumin synthesis than did the other groups.
To summarize, our data demonstrate that vitamin C plays an important role in liver regeneration, at least in part by regulating the signaling pathways involved in hepatocyte proliferation. The present study is the first report to demonstrate that vitamin C promotes liver regeneration. Moreover, these results suggest that vitamin C might be useful to accelerate liver regeneration after liver resection and transplantation.
Acknowledgements
This research was supported by Bio-industry Technology Development Program (312062-5) of iPET (Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries), Ministry for Food, Agriculture, Forestry and Fisheries, Republic of Korea.
References
Albrecht J. H. , Hansen L. K. 1999 Cyclin D1 promotes mitogen-independent cell cycle progression in hepatocytes Cell Growth Differ. 10 397 - 404
Arrigoni O. , Arrigoni-Liso R. , Calabrese G. 1976 Ascorbic acid as a factor controlling the development of cyanide-insensitive respiration Science 194 332 - 333    DOI : 10.1126/science.194.4262.332
Attisano L. , Carcamo J. , Ventura F. , Weis F. M. , Massagué J. , Wrana J. L. 1993 Identificat ion of human activin and TGFβ type Ⅰ receptors that form heteromeric kinase complexes with type Ⅱ receptors Cell 75 671 - 680    DOI : 10.1016/0092-8674(93)90488-C
Behrens A. , Sibilia M. 2002 Impaired postnatal hepatocyte proliferation and liver regeneration in mice lacking c-jun in the liver EMBO J. 21 1782 - 1790    DOI : 10.1093/emboj/21.7.1782
Bohmer J. A. , Sellhause B. , Schrage N. F. 2001 Effect of ascorbic acid on retinal pigment epithelial cells Curr. Eye Res. 23 (3) 206 - 214    DOI : 10.1076/ceyr.23.3.206.5464
Borowiak M. , Garratt A. N. , Wustefeld T. , Strehle M. , Trautwein C. , Birchmeier C. 2004 Met provides essential signals for liver regeneration Proc. Natl. Acad. Sci. USA 101 10608 - 10613    DOI : 10.1073/pnas.0403412101
raun L. , Mead J. E. , Panzica M. , Mikumo R. , Bell G. I. , Fausto N. 1988 Transforming growth factor-β mRNA increases during liver regeneration: a possible paracrine mechanism of growth regulation Proc. Natl. Acad. Sci. USA 85 1539 - 1543    DOI : 10.1073/pnas.85.5.1539
Chen H. , Yang S. , Yang Z. , Ma L , Jiang D. , Mao J. , Jiao B. , Cai Z. 2007 Inhibition of GSK-3beta decreases NF-kappaB-dependent gene expression and impairs the rat liver regeneration J. Cell Biochem. 102 1281 - 1289    DOI : 10.1002/jcb.21358
Cressman D. E. , Greenbaum L. E. 1996 Liver failure and defective hepatocyte regeneration in interleukin 6-deficient mice Science 274 1379 - 1383    DOI : 10.1126/science.274.5291.1379
Fan G. , Xu R. , Wessendorf M. W. , Ma X. , Kren B. T. , Steer C. J. 1995 Modulation of retinoblastoma and retinoblastoma-related proteins in regenerating rat liver and primary hepatocytes Cell Growth Differ. 6 1463 - 1476
Fausto N. 2006 Liver regeneration Hepatology 43 S45 - S53    DOI : 10.1002/hep.20969
Fujita T. , Uchida K. , Maruyama N. 1992 Purification of senescence marker protein-30 (SMP30) and its androgen-independent decrease with age in the rat liver Biochim. Biophys. Acta 1116 122 - 128    DOI : 10.1016/0304-4165(92)90108-7
Fujita T. , Uchida K. , Maruyama N. 1996 Isolation and characterization of genomic and cDNA clones encoding mouse senescence marker protein-30 (SMP30) Biochem. Biophys. Acta 1308 49 - 57
Grimes C. A. , Jope R. S. 2001 The multifaceted roles of glycogen synthase kinase 3 beta in cellular signaling Prog. Neurobiol. 65 391 - 426    DOI : 10.1016/S0301-0082(01)00011-9
Gruppuso P. A. 1989 Expression of hepatic transforming growth factor receptors during late gestation in the fetal rat Endocrinology 125 3037 - 3043    DOI : 10.1210/endo-125-6-3037
Ishigami A. , Fujita T. , Handa S. , Shirasawa T. , Koseki H. , Kitamura T. , Enomoto N. , Sato N. , Shimosawa T. , Maruyama N. 2002 Senescence marker protein-30 knockout mouse liver is highly susceptible to tumor necrosis factor-alphaand Fas-mediated apoptosis Am. J. Pathol. 161 1273 - 1281    DOI : 10.1016/S0002-9440(10)64404-5
Jeong J. J. , Heo S. H. , Kim J. H. , Yoon K. H. , Lee Y. J. , Han K. B. , Kim W. J. 2010 Effects of rrhGM-CSF on Morphology and expression of PCNA in regenerating rat liver Kor. J. Microscopy 40 73 - 80
Kondo Y. , Sasaki T. , Sato Y. , Amano A. , Aizawa S. , Iwama M. , Handa S. , Shimada N. , Fukuda M. , Akita M. , Lee J. , Jeong K. S. , Maruyama N. , Ishigami A. 2008 Vitamin C depletion increases superoxide generation in brains of SMP30/GNL knockout mice Biochem. Biophys. Res. Commun. 377 291 - 296    DOI : 10.1016/j.bbrc.2008.09.132
Leu J. I. , Crissey M. A. , Craig L. E. , Taub R. 2003 Impaired hepatocyte DNA synthetic response posthepatectomy in insulin-like growth factor binding protein 1-deficient mice with defects in C/EBP beta and mitogen-activated protein kinase/extracellular signal-regulated kinase regulation Mol. Cell Biol. 23 1251 - 1259    DOI : 10.1128/MCB.23.4.1251-1259.2003
Mapson L. W. 1961 The estimation of dehydro-L-ascorbic acid when present in low concentration in tissues by the Roe and Kuether procedure Ann. N. Y. Acad. Sci. 92 284 - 285    DOI : 10.1111/j.1749-6632.1961.tb46127.x
Michalopoulos G. K. 2007 Liver regeneration J. Cell Physiol. 213 286 - 300    DOI : 10.1002/jcp.21172
Michalopoulus G. K. , Defrances M. C. 1997 Liver regeneration Science 276 60 - 66    DOI : 10.1126/science.276.5309.60
Michalopoulos G. K. , Khan Z. 2005 Liver regeneration, growth factors and amphiregulin Gastroenterology 128 503 - 506    DOI : 10.1053/j.gastro.2004.12.039
Nakamura T. 1994 Hepatocyte growth factor as mitogen, motogen and morphogen and its roles in organ regeneration Princess Takamatsu Symp. 24 195 - 213
Nathwani R. A. , Pais S. , Reynolds T. B. , Kaplowitz N. 2005 Serum alanine aminotransferase in skeletal muscle disease Hepatology 41 380 - 382    DOI : 10.1002/hep.20548
Park J. K. , Jeong D. H. , Park H. Y. , Son K. H. , Shin D. H. , Do S. H. , Yang H. J. , Yuan D. W. , Hong I. H. , Goo M. J. , Lee H. R. , Ki M. R. , Ishigami A. , Jeong K. S. 2008 Hepatoprotective effect of Arazyme on CCl4-induced acute hepatic injury in SMP30 knockout mice Toxicology 246 132 - 142    DOI : 10.1016/j.tox.2008.01.006
Price C. E. 1996 Ascorbate stimulation of RNA synthesis Nature 212 1481 -
Pulverer B. J. , Kyriakis J. M. , Avruch J. , Nikolakaki E. , Woodgett J. R. 1991 Phosphorylation of c-jun mediated by Map kinase Nature 353 670 - 674    DOI : 10.1038/353670a0
Servillo G. , Penna L. 1997 Cyclic AMP signalling pathway and cellular proliferation: induction of CREM during liver regeneration Oncogene 14 1601 - 1606    DOI : 10.1038/sj.onc.1200996
Seth A. , Gonzalez F. A. , Gupta S. , Raden D. L. , Davis R. J. 1992 Signal transduction within the nucleus by mitogen-activated protein kinase J. Biol. Chem. 267 24796 - 24804
Shakoori A. , Mai W. , Miyashita K. , Yasumoto K. , Takahashi Y. , Ooi A. , Kawakami K. , Minamoto T. 2007 Inhibition of GSK-3 beta activity attenuates proliferation of himan colon cancer cells in rodents Cancer Sci. 98 1388 - 1393    DOI : 10.1111/j.1349-7006.2007.00545.x
Spiewak Rinaudo J. A. , Thorgeirsson S. S. 1997 Detection of a tyrosine-phosphorylated form of cyclin A during liver regeneration Cell Growth Differ. 8 301 - 309
Stain A. J. , Frazer A. , Hill D. J. , Milner R. D. 1987 Transforming growth factor β inhibits DNA synthesis in hepatocytes isolated from normal and regenerating rat liver Biochem. Biophys. Res. Commun. 145 436 - 442    DOI : 10.1016/0006-291X(87)91340-4
Strain A. J. , Hill D. J. 1990 Changes in sensitivity of hepatocytes isolated from regenerating rat liver to the growth inhibitory action of transforming growth factor beta Liver 10 282 - 290
Talarmin H. , Rescan C. , Cariou S. , Glaise D. , Zanninelli G. , Bilodeau M. , Loyer P. , Guguen-Guillouzo C. , Baffet G. 1999 The mitogen-activated protein kinase kinase/extracellular signal-regulated kinase cascade activation is a key signalling pathway involved in the regulation of G(1) phase progression in proliferating hepatocytes Mol. Cell Biol. 19 6003 - 6011
Taub R. 2004 Liver regeneration: from myth to mechanism Nat. Rev. Mol. Cell Biol. 5 836 - 847    DOI : 10.1038/nrm1489
Traber M. G. , Stevens J. F. 2011 Vitamin C and E: Beneficial effects from a mechanistic perspective Free Radic. Biol. Med. 51 1000 - 1013    DOI : 10.1016/j.freeradbiomed.2011.05.017
Woodgett J. R. 1990 Molecular cloning and expression of glycogen synthase kinase 3/factor A EMBO J. 9 2431 - 2438
Taira Z. , Shiraishi M. , Ueda Y. 2005 An abnormal proliferation at day four on 70% partial hepatectomy of rats J. Hard Tissue Biology (supplement) 14 351 - 352    DOI : 10.2485/jhtb.14.351
Xiong Y. , Connolly T. , Futcher B. , Beach D. 1991 Human D-type cyclin Cell 65 691 - 699    DOI : 10.1016/0092-8674(91)90100-D
Yeoh G. C. , Ernst M. , Rose-John S. , Akhurst B. , Payne C. , Long S. , Alexander W. , Croker B. , Grail D. , Matthews V. B. 2007 Opposing roles of gp130-mediated STAT-3 and ERK-1/2 signaling in liver progenitor cell migration and proliferation Hepatology 45 486 - 494    DOI : 10.1002/hep.21535