The in vivo effect of hepatotrophic factors augmenter of liver regeneration, hepatocyte growth factor, and insulin-like growth factor-II on liver natural killer cell functions

Blocking the short isoform of augmenter of liver regeneration inhibits proliferation of human multiple myeloma U266 cells via the MAPK/STAT3/cell cycle signaling pathway

Multiple myeloma (MM) is the second most common haematological malignancy and remains an incurable disease, with most patients relapsing and requiring further treatment. Augmenter of liver regeneration (ALR) is a vital protein affecting fundamental processes such as energy transduction, cell survival and regeneration. Silencing ALR inhibits cell proliferation and triggers apoptosis in human MM U266 cells. However, little is known about the role of 15-kDa-ALR on MM. In the present study, the role of 15-kDa-ALR in human MM cells was investigated. Blocking extracellular 15-kDa-ALR with an anti-ALR monoclonal antibody (McAb) decreased the proliferation and viability of U266 cells. However, the results of flow cytometry revealed no changes in apoptosis, and the expression levels of Bax, Bcl-2, caspase-3 and cleaved caspase-3 were not affected. However, combined treatment with anti-ALR McAb and epirubicin increased the apoptosis of U266 cells. RNA sequencing results indicated that the ERK1/2, JNK-MAPK and STAT3 signaling pathways, as well as the cell cycle, were associated with the mechanism of action of the anti-ALR McAb, and PCR, western blotting and cell cycle analysis confirmed these results. The present findings suggested that blocking extracellular 15-kDa-ALR in U266 cells with an anti-ALR McAb decreased cell proliferation via the MAPK, STAT3 and cell cycle signaling pathways without increasing apoptosis. Thus, 15-kDa-ALR may be a new therapeutic target for myeloma.

NAFLD Preclinical Models: More than a Handful, Less of a Concern?

Non-alcoholic fatty liver disease (NAFLD) is a spectrum of liver diseases ranging from simple steatosis to non-alcoholic steatohepatitis, fibrosis, cirrhosis, and/or hepatocellular carcinoma. Due to its increasing prevalence, NAFLD is currently a major public health concern. Although a wide variety of preclinical models have contributed to better understanding the pathophysiology of NAFLD, it is not always obvious which model is best suitable for addressing a specific research question. This review provides insights into currently existing models, mainly focusing on murine models, which is of great importance to aid in the identification of novel therapeutic options for human NAFLD.

Insights on augmenter of liver regeneration cloning and function

Hepatic stimulator substance (HSS) has been referred to as a liver-specific but species non-specific growth factor. Gradient purification and sequence analysis of HSS protein indicated that it contained the augmenter of liver regeneration (ALR), also known as hepatopoietin (HPO). ALR, acting as a hepatotrophic growth factor, specifically stimulated proliferation of cultured hepatocytes as well as hepatoma cells in vitro, promoted liver regeneration and recovery of damaged hepatocytes and rescued acute hepatic failure in vivo. ALR belongs to the new Erv1/Alr protein family, members of which are found in lower and higher eukaryotes from yeast to man and even in some double-stranded DNA viruses. The present review article focuses on the molecular biology of ALR, examining the ALR gene and its expression from yeast to man and the biological function of ALR protein. ALR protein seems to be non-liver-specific as was previously believed, increasing the necessity to extend research on mammalian ALR protein in different tissues, organs and developmental stages in conditions of normal and abnormal cellular growth.

Expression of human augmenter of liver regeneration in pichia pastoris yeast and its bioactivity in vitro

AIM

To construct a yeast expression system of human augmenter of liver regeneration (hALR) and to examine its bioactivity in vitro.

METHODS

With PCR and gene recombination techniques, cDNA of open reading frame of hALR was obtained from recombinant plasmid pcDNA3.1-hALR and inserted into plasmid pPIC9. The cDNA of hALR from recombinant plasmid pPIC9-hALR demonstrated by sequencing was subcloned into plasmid pPIC9K. The recombinant plasmid pPIC9K-hALR was transformed into GS115 with electroporation. hALR was expressed by GS115 under the induction of 5 mL/L methanol and purified with ultrafiltration after it was analyzed by 15% SDS-PAGE and Western blot. The effects of hALR on in vitro proliferation of QGY and HepG(2) cells were evaluated by (3)H-TdR methods.

RESULTS

The correctness and integrity of recombinant plasmids pPIC9-hALR and pPIC9K-hALR were identified by restriction digestion, PCR and sequencing methods, respectively. hALR as a secretive protein was successfully expressed by GS115. Its molecular weight was about 15 ku and the target protein was about 60% of the total protein in the supernatant from GS115 with plasmid pPIC9K-hALR. The results of Western blot of hALR showed the specific band. The high qualitative hALR was obtained through ultrafiltration. hALR could stimulate in vitro proliferation of QGY and HepG(2) cells in a dose-dependent manner, but there was a difference in reactivity to hALR between QGY and HepG(2).

CONCLUSION

The hALR as a secretive protein can be successfully expressed by GS115. It may stimulate in vitro proliferation of QGY and HepG(2) cells at a dose-dependent manner. But QGY and HepG(2) cells have different reactivities to hALR.

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Screening and identification of genes transactivated by human augmenter of liver regeneration by microarray assay

AIM: Augmenter of liver regeneration (ALR) is a protein that plays a role in liver regeneration. In order to clarify the effect of the expression of ALR on profile of the hepatocytic gene expression, we analyzed difference between the HepG2 cells transfected with ALR and controls by using gene chip technology.

METHODS: Total RNA was extracted from HepG2 cells,and RT-PCR was performed to amplify the coding region of ALR. The expression of ALR in the transfected HepG2 cells was confirmed by Western blot. Total mRNA was isolated from the transfected HepG2 cells with pcDNA3.1(-) and pcDNA3-ALR, respectively. cDNA was prepared by reverse transcription. Microarray assay was conducted for screening of up-and down-regulated genes in both HepG2 cells.

RESULTS: The expressive vector of pcDNA3(-)-ALR was constructed and confirmed by restriction enzyme digestion and DNA sequencing. The expression of ALR was confirmed by Western blot. After screening with cDNA microarray, we found 2 genes were up-regulated, and 24 genes including TNFRSF1A-associated via death domain, tissue inhibitor of metalloproteinase 1, epididymal androgen-related protein, down-regulated.

CONCLUSION: ALR is a cell growth factor, which has some influences on gene expression profile of hepatocytes; Microarray technology is a method to analyze gene expression spectra of trans-regulation of a protein and conducive to understand the regulative effect of ALR on hepatocytes and other biological function.

Identification and characterization of a novel isoform of hepatopoietin

AIM: To isolate a novel isoform of human HPO (HPO-205) from human fetal liver Marathon-ready cDNA and characterize its primary biological function.

METHODS: 5'-RACE (rapid amplification of cDNA 5’ends) was used to isolate a novel isoform of hHPO in this paper. The constructed pcDNA^HPO-205, pcDNA^HPO and pcDNA eukaryotic expression vectors were respectively transfected by lipofectamine method and the stimulation of DNA synthesis was observed by ³H-TdR incorporation assay. Proteins extracted from different cells were analyzed by Western blot.

RESULTS: A novel isoform of hHPO (HPO-205) encoding a 205 amino acid ORF corresponding to a translated production of 23 kDa was isolated and distinguished from the previous HPO that lacked the N-terminal 80 amino acids. The dose-dependent stimulation of DNA synthesis of HepG2 hepatoma cells by HPO-205 demonstrated its similar biological activity with HPO in vitro. The level of MAPK (Mitogen-activated protein kinase) phosphorylation by Western blot analysis revealed that HPO-205 might have the stronger activity of stimulating hepatic cell proliferation than that of HPO.

CONCLUSION: A novel isoform of hHPO (HPO-205) was isolated from hepatic-derived cells. The comparison of HPO-205 and HPO will lead to a new insight into the structure and function of hHPO, and provide the new way of thinking to deeply elucidate the biological roles of HPO/ALR.