[Effect of autophagy on liver regeneration].

Autophagy is a lysosome-mediated degradation pathway, which plays an important role in hepatic physiological and pathological processes, in eukaryotic cells. The liver has a remarkable regenerative capacity. After acute or chronic injury, the residual hepatic cells can be activated to enter the cell-cycle for proliferation, in order to compensate for lost liver tissue and recover liver function. In this review, we summarize the relationship between liver regeneration (LR) after various types of injury and autophagy. For example, autophagy is activated to accelerate LR after physically, alcohol and food borne induced liver injury, while the role of autophagy in animal models of LR after chemical injury remains controversial. Autophagy can also be used to promote the replication of virus particles by some hepatotropic viruses (e.g., HBV, HCV) and inhibit LR after viral infection. Studies on mechanisms of autophagy and LR will contribute to clarify the regenerative process and provide new methods for the treatment of liver disease.

iTRAQ-based proteomic analysis of adaptive response in the regenerating limb of the Cynops orientalis newt.

The newt has the powerful capacity to regenerate lost limbs following amputation, and represents an excellent model organism to study regenerative processes. However, the molecular basis of the adaptive response in the regenerating limb of the Chinese fire-bellied newt Cynops orientalis immediately after amputation remains unclear. To better understand the adaptive response immediately after limb amputation at the protein level, we used isobaric tags for relative and absolute quantitation (iTRAQ) coupled with LC-MS/MS methods to analyze changes in the proteome of the regenerating newt limb that occurred 2 h and 8 h after amputation. We identified 152 proteins with more than 1.5-fold change in expression compared to control. GO annotation analysis classified these proteins into several categories such as signaling, Ca(2+) binding and translocation, transcription and translation, immune response, cell death, cytoskeleton, metabolism, etc. Further ingenuity pathway analysis (IPA) showed that several signaling pathways were significantly changed at 2 h and 8 h after amputation, including EIF2 signaling, acute phase response signaling, tight junction signaling and calcium signaling, suggesting these pathways may be closely related to the adaptive response immediately after limb amputation. This work provides novel insights into understanding the molecular processes related to newt limb regeneration immediately after amputation, and a basis for further study of regenerative medicine.

Proteomic analysis of the regenerating liver following 2/3 partial hepatectomy in rats.

BACKGROUND: Liver regeneration (LR) after 2/3 partial hepatectomy (PH) is one of the most studied models of cell, organ, and tissue regeneration. Although the transcriptional profile analysis of regenerating liver has been carried out by many reserachers, the dynamic protein expression profile during LR has been rarely reported up to date. Therefore, this study aims to detect the global proteomic profile of the regenerating rat liver following 2/3 hepatectomy, thereby gaining some insights into hepatic regeneration mechanism. RESULTS: Protein samples extracted from the sham-operated and the regenerating rat livers at 6, 12, 24, 72, 120 and 168 h after PH were separated by IEF/SDS-PAGE and then analyzed by MALDI-TOF/TOF mass spectrometry. Compared to sham-operated groups, there were totally 220 differentially expressed proteins (including 156 up-regulated, 62 down-regulated, and 2 up/down-regulated ones) identified in the regenerating rat livers, and most of them have not been previously related to liver regeneration. According to the expression pattern analysis combined with gene functional analysis, it showed that lipid and carbohydrate metabolism were enhanced at the early phase of LR and continue throughout the regeneration process. Ingenuity Pathway Analysis indicated that YWHAE protein (one of members of the 14-3-3 protein family) was located at the center of pathway networks at all the timepoints after 2/3 hepatectomy under our experimental conditions, maybe suggesting a central role of this protein in regulating liver regeneration. Additionally, we also revealed the role of Cdc42 (cell division cycle 42) in the termination of LR. CONCLUSIONS: For the first time, our proteomic analysis suggested an important role of YWHAE and pathway mediated by this protein in liver regeneration, which might be helpful in expanding our understanding of LR amd unraveling the mechanisms of LR.

Proteomic analysis of the regenerating liver following 2/3 partial hepatectomy in rats

BACKGROUND: Liver regeneration (LR) after 2/3 partial hepatectomy (PH) is one of the most studied models of cell, organ, and tissue regeneration. Although the transcriptional profile analysis of regenerating liver has been carried out by many reserachers, the dynamic protein expression profile during LR has been rarely reported up to date. Therefore, this study aims to detect the global proteomic profile of the regenerating rat liver following 2/3 hepatectomy, thereby gaining some insights into hepatic regeneration mechanism. RESULTS: Protein samples extracted from the sham-operated and the regenerating rat livers at 6, 12, 24, 72, 120 and 168 h after PH were separated by IEF/SDS-PAGE and then analyzed by MALDI-TOF/TOF mass spectrometry. Compared to sham-operated groups, there were totally 220 differentially expressed proteins (including 156 up-regulated, 62 down-regulated, and 2 up/down-regulated ones) identified in the regenerating rat livers, and most of them have not been previously related to liver regeneration. According to the expression pattern analysis combined with gene functional analysis, it showed that lipid and carbohydrate metabolism were enhanced at the early phase of LR and continue throughout the regeneration process. Ingenuity Pathway Analysis indicated that YWHAE protein (one of members of the 14-3-3 protein family) was located at the center of pathway networks at all the timepoints after 2/3 hepatectomy under our experimental conditions, maybe suggesting a central role of this protein in regulating liver regeneration. Additionally, we also revealed the role of Cdc42 (cell division cycle 42) in the termination of LR. CONCLUSIONS: For the first time, our proteomic analysis suggested an important role of YWHAE and pathway mediated by this protein in liver regeneration, which might be helpful in expanding our understanding of LR amd unraveling the mechanisms of LR.

[Characterization and identification of functional elements in non-coding DNA sequences].

The non-coding DNA sequences refer to non-protein-coding DNA sequences in genome. These sequences can bind with transcription factors or be transcribed as functional RNAs, thus participating in the regulation of many physiological activities and pathological processes. Aiming at gene expression regulation, this review focuses on the recent progress of non-coding DNA and illustrates their structures, functions and potential acting mechanisms. Meanwhile, some computational and experimental methods of identifying functional elements in the non-coding DNAs are introduced. Finally, further studies in this field are proposed.

The role of Kupffer cells in rat liver regeneration revealed by cell-specific microarray analysis.

Liver regeneration after partial hepatectomy is a process with various types of cells involved. The role of Kupffer cells (KCs) in liver regeneration is still controversial. In this study we isolated KCs from regenerating liver and conducted cell-specific microarray analysis. The results demonstrated that the controversial role of KCs in liver regeneration could be explained with the expression patterns of TGF-α, IL-6, TNF, and possibly IL-18 during liver regeneration. IL-18 may play an important role in negative regulation of liver regeneration. The functional profiles of gene expression in KCs also indicated that KC signaling might play a negative role in cell proliferation: signaling genes were down regulated before cell division. Immune response genes in KCs were also down regulated during liver regeneration, demonstrating similar expression profiles to that of hepatocytes. The expression patterns of key genes in these functional categories were consistent with the temporal functional profiles.

The number of the genes in a functional category matters during rat liver regeneration after partial hepatectomy.

Rat liver regeneration after partial hepatectomy (PH) is a good model to study the regulation of cell proliferation. We isolated hepatocytes from regenerating liver at different time points after PH and used microarray Rat Genome 230 2.0 chip to analyze the functional profiles of all up- or down-regulated genes manually and with automatic gene ontological tools. We found that the transcript expressions of PH and sham operation group were apparently different. For PH group, in the priming phase (2-12 h), signaling, transcription, response to stimulus genes predominated in up-regulated genes; in the proliferation phase (24-72 h), cell proliferation genes predominated; in the termination phase (120-168 h), differentiation and translation genes predominated; while metabolism genes predominated in the down-regulated genes at all time points (2-168 h). These functional profiles are consistent with the cellular and molecular phenomenon observed during liver regeneration, and can be closely connected with the biological process. Moreover, the results indicated that not only the quantity of specific genes but also the number of the genes in the specific functional category was regulated during liver regeneration, which means the number of similar genes in a specific functional category matters as well as the regulation of the genes. The changes of the number of the regulated cell proliferation genes and metabolism genes during liver regeneration were similar to the expression patterns of some cell division genes and metabolism genes.

Alterations in DNA repair gene expression and their possible regulation in rat-liver regeneration.

Rapidly proliferating tissue may require enhanced DNA repair capacity in order to avoid fixation of promutagenic DNA lesions to mutations. Partial hepatectomy (PH) triggers cell proliferation during liver regeneration (LR). However, little is known on how DNA repair genes change and how they are regulated at the transcriptional level during LR. In the present study, the Rat Genome 230 2.0 array was used to detect the expression profiles of DNA repair genes during LR, and differential expression of selected genes was confirmed by real-time RT-PCR. 69 DNA repair genes were found to be associated with LR, more than half of which distributed in a cluster characterized by a gradual increase at 24-72h and then returning to normal. The expression of base excision repair- and transcription-coupled repair-related genes was enhanced in the early and intermediate phases of LR, whereas the expression of genes related to HR, NHEJ and DNA cross-link repair, as well as DNA polymerases and related accessory factors, and editing or processing nucleases, were mainly enhanced in the intermediate phase. The expression changes of genes in DNA damage response were complicated throughout the whole LR. Our data also suggest that the expression of most DNA repair genes may be regulated by the cell cycle during LR.

Fusion of core pathways reveals a horizontal synergistic mechanism underlying combination therapy.

Combination therapies have recently been shown to be more effective than monotherapies that may provide synergistic effects in the treatment of stroke, but its selective mechanism still remains unclear. Based on the median-effect method, the combination therapy of jasminoidin and ursodeoxycholic acid had a synergic effect on reducing the infarct volume. The numbers of up- or down-regulated genes by at least 1.5-fold in the vehicle, jasminoidin, ursodeoxycholic acid, and the combination of jasminoidin and ursodeoxycholic acid treatment groups were 228, 95, 136, and 101, respectively. According to clustering and principal component analysis, the pattern of gene expression in the combination group was similar to that of jasminoidin group rather than ursodeoxycholic acid group. Based on these nine top sequences in the combination group excluding four overlapping pathways (MAPK-ERK, Kitlg, Icam1-Ap1, and prolactin), the jasminoidin group had four (PRLR-STAT1, AcvR2-AcvR1B, ACVR1/2A-SMAD1, GHR-NF-κB) contributing pathways, and the ursodeoxycholic acid group had one (IL-6) contributing pathway. Based on the multiple-pathway-dependent comparison analysis (MPDCA), it may lead to the conclusion that jasminoidin possibly contributes more important pharmacological effect in the combined treatment as jasminoidin regulated 80% of the pathways that the combination group mediated. The study reveals a horizontal synergistic effect by optimizing the fusion of more pathways from the compounds with more contribution to the combination therapy. Rather than selecting compounds only based on experience in the past, this study would give a new insight into the systematic strategies for designing synergistic combination therapies.

[Three novel genes BM390716, BI274487 and AA963863 involed in extracellular matrix metabolism of eight rat regenerating liver cell types].

To explore the roles of three novel genes BM390716, BI274487 and AA963863 and the correlation between them during liver regeneration of rats, eight kinds of liver cells were isolated using the combined percoll density gradient centrifugation and immunomagnetic bead method. Rat genome 230 2.0 array was used to detect the changes in expression of genes involved in metabolism of extracellular matrix and the novel genes in rat genome. Correlation between sequence homology, co-expression of the above genes and the physiological activities they involed in were analyzed using Microsoft Excel and BLAST software. The results showed that BM390716 was homologous to and co-expressed with pparα, BI274487 was homologous to and co-expressed with timp2, and AA963863 was homologous to and co-expressed with csgalnact1. It is predicted that BM390716, BI274487, and AA963863 were involved in extracellular matrix metabolism in eight types of rat regenerating liver cells.

Analysis of time-course gene expression profiles of sinusoidal endothelial cells during liver regeneration in rats.

Liver regeneration (LR) after partial hepatectomy (PH) requires the coordinate contribution of different cell types. Liver sinusoidal endothelial cells (LSECs), representing the largest population of nonparenchymal cells, are proven to be crucial in LR. However, the details about their implications in regeneration are not still clear. In this study, percoll density centrifugation and immunomagentic bead methods were used to isolate LSECs with high purity and yield; global transcriptional profiles of LSECs during the regeneration were investigated by microarray. 1,629 genes were identified to be LR-related. Among them, there were 833 known genes whose expression patterns were clustered into eight classes. Gene function enrichment analysis showed that genes involved in the major LSEC functions, i.e., coagulation, phagocytosis, and transport, were highly enriched in cluster characterized by rapid induction and gradual return, suggesting the quick reestablishment of LSEC function after PH. Genes in immunity/inflammation and defense response were enriched in clusters exhibiting transient downregulation and quick recovery, possibly being associated with suppression of immunity/inflammation pathway in LSECs at early phase. Genes in glycogen synthesis and glycolysis were enriched in the clusters marked by "significant increase and gradual return" and "slight increase and then downregulation", implying an enhanced carbohydrate metabolism at early phase; detoxification-related genes were markedly distributed in the cluster with feature of rapid increase and then reduction, which was helpful in eliminating waste substance. Taken together, the measurement of gene expression profiling of LSECs and expression pattern analysis of functionally categorized genes gave insight into the mechanism of action of this cell on LR.

Alterations in DNA repair gene expression and their possible regulation in rat-liver regeneration

Rapidly proliferating tissue may require enhanced DNA repair capacity in order to avoid fixation of promutagenic DNA lesions to mutations. Partial hepatectomy (PH) triggers cell proliferation during liver regeneration (LR). However, little is known on how DNA repair genes change and how they are regulated at the transcriptional level during LR. In the present study, the Rat Genome 230 2.0 array was used to detect the expression profiles of DNA repair genes during LR, and differential expression of selected genes was confirmed by real-time RT-PCR. 69 DNA repair genes were found to be associated with LR, more than half of which distributed in a cluster characterized by a gradual increase at 24-72h and then returning to normal. The expression of base excision repair- and transcription-coupled repair-related genes was enhanced in the early and intermediate phases of LR, whereas the expression of genes related to HR, NHEJ and DNA cross-link repair, as well as DNA polymerases and related accessory factors, and editing or processing nucleases, were mainly enhanced in the intermediate phase. The expression changes of genes in DNA damage response were complicated throughout the whole LR. Our data also suggest that the expression of most DNA repair genes may be regulated by the cell cycle during LR.

[Transcriptome atlas of serine family amino acid metabolism-related genes in eight rat regenerating liver cell types.].

To explore the transcription profiles of serine family amino acid metabolism-related genes in eight liver cell types during rat liver regeneration (LR), eight types of rat regenerating liver cells were isolated using the combination of percoll density gradient centrifugation and immunomagnetic bead methods. Then, the expression profiles of the genes associated with metabolism of serine family amino acid in rat liver regeneration were detected by Rat Genome 230 2.0 Array. The expression patterns of these genes were analyzed through the software of Cluster and Treeview. The activities of serine family amino acid metabolism were analyzed by the methods of bioinformatics and systems biology. The results showed that 27 genes were significantly expressed. Among them, the numbers of genes showing significant expression changes in hepatocytes, biliary epithelial cells, oval cells, hepatic stellate cells, sinusoidal endothelial cells, Kupffer cells, pit cells and dendritic cells were 13, 16, 11, 14, 13, 11, 12, and 14, respectively. The numbers of up-, down-, and up-/down-regulated genes in corresponding cells were 7, 6, and 0; 2, 10, and 4; 2, 8, and 1; 8, 3, and 3; 6, 5, and 2; 4, 6, and 1; 2, 10, and 0; and 6, 6, and 2. Overall, the genes in the eight types of cells were mostly down-regulated during liver regeneration, but most LR-related genes in hepatic stellate cells and sinusoidal endothelial cells were up-regulated in priming phase. It is suggested that biosynthesis of serine family amino acid was enhanced in hepatocytes, hepatic stellate cells, sinusoidal endothelial cells and Kupffer cells in the priming phase. The catabolism of them was enhanced in hepatocytes, biliary epithelial cells, pit cells and dendritic cells in progressive phase.

Reference gene selection for real-time RT-PCR in eight kinds of rat regenerating hepatic cells.

Liver regeneration (LR) is a process during which the liver recovers its mass and function after damage due to various causes such as partial hepatectomy (PH). It involves a sequence of well-orchestrated changes in physiological and biochemical activities, especially in the gene expression profile in a variety of liver cells. In order to produce reliable gene expression of target genes in eight kinds of rat hepatic cells during LR, the determination of internal control housekeeping genes (HKGs) is required. Eight kinds of hepatic cells were first isolated from liver tissue with high purity and activity. Then quantitative real-time reverse transcription (RT)-PCR was applied to detect expression changes of six commonly used HKGs (18SrRNA, B2M, ACTB, UBC, GAPDH, and HK1) in eight types of hepatic cells isolated from regenerating liver at 0, 2, 6, 12, 24, 30, 36, 72, 120, and 168 h after PH. The amplification of the HKGs was statistically analyzed by using geNorm algorithm. Using this method, 18SrRNA-UBC, ACTB-HK1, ACTB-GADPH, B2M-ACTB, 18SrRNA-UBC, B2M-UBC, B2M-ACTB, and B2M-UBC were found to be the two most stable reference genes for rat regenerating hepatocytes, hepatic stellate cells, Kupffer cells, biliary epithelial cells, sinusoidal endothelial cells, pit cells, dendritic cells, and oval cells, respectively, regardless of the stages of LR. In conclusion, this study has laid a good foundation for investigating gene expression of target genes in different types of hepatic cells during LR.

Pancreatic secretory trypsin inhibitor: More than a trypsin inhibitor.

Kazal-type serine protease inhibitor is one of the most important and widely distributed protease inhibitor families. Pancreatic secretory trypsin inhibitor (PSTI), also known as serine protease inhibitor Kazal type I(SPINK1), binds rapidly to trypsin, inhibits its activity and is likely to protect the pancreas from prematurely activated trypsinogen. Therefore, it is an important factor in the onset of pancreatitis. Recent studies found that PSTI/SPINK1 is also involved in self-regulation of acinar cell phagocytosis, proliferation and growth of a variety of cell lines. In addition, it takes part in the response to inflammatory factor or injury and is highly related to adult type II citrullinemia.

Study on correlation of signal molecule genes and their receptor-associated genes with rat liver regeneration.

To investigate the effect of signal molecules and their receptor-associated genes on rat liver regeneration (LR) at the transcriptional level, the associated genes were originally obtained by retrieving the databases and related scientific publications; their expression profiles in rat LR were then checked using the Rat Genome 230 2.0 microarray. The LR-associated genes were identified by comparing gene expression difference between partial hepatectomy groups and operation-control groups. A total of 454 genes were proved to be LR related. The genes associated with the seven kinds of signal molecules (steroid hormones, fatty acid derivatives, protein and polypeptide hormones, amino acids and their derivatives, choline, cytokines, and gas signal molecules) were detected to be enriched in a cluster characterized by upregulated expression in LR. The number of genes related to the seven kinds of signal molecules was, in sequence, 63, 27, 100, 102, 16, 166, and 18. The 1027 frequencies of upregulation and 823 frequencies of downregulation in total as well as 42 types of different expression patterns suggest the complex and diverse gene expression changes in LR. It is presumed that signal molecules played an important role in metabolism, inflammation, cell proliferation, growth and differentiation, etc., during rat LR.

Possible regulation of genes associated with intracellular signaling cascade in rat liver regeneration.

OBJECTIVE: The importance of signal transduction in cell activities has been generally accepted. The purpose of this study was to analyze the regulatory effect of intracellular signaling cascade-associated genes on rat liver regeneration (LR) at transcriptional level. MATERIAL AND METHODS: The associated genes were originally obtained through a search of the databases and related scientific publications; their expression profiles were then checked in rat LR using the Rat Genome 230 2.0 array. The LR-associated genes were identified by comparing the discrepancy in gene expression changes between the partial hepatectomy (PH) group and the sham operation (SO) group. RESULTS: A total of 566 genes associated with the intracellular signaling cascade were LR related. The genes involved in nine signaling pathways including intracellular receptor-, second messenger-, nitric oxide-, hormone-, carbohydrate-mediated, protein kinase, small GTPase, ER-nuclear and target of rapamycin (TOR) signaling pathways were detected to be enriched in a cluster characterized by up-regulated expression in LR. According to their expression similarity and time relevance, they were separately classified into 5 and 5 groups. CONCLUSIONS: It is presumed that following PH, the second messenger-mediated signaling pathway inhibits the inflammatory response, while the protein kinase cascade and small GTPase-mediated signal transduction stimulate the immune response; the intracellular receptor-, second messenger-, small GTPase-mediated signal transduction and protein kinase cascade coordinately control cell replication; the intracellular receptor-, second messenger-mediated and ER-nuclear signaling pathways facilitate cell differentiation; the MAPK cascade and small GTPase-mediated signal transduction play a role in cytoskeletal reconstruction and cell migration; the second messenger-, small GTPase-mediated and IkappaB kinase/NFkappaB cascades take care of protein transport, etc., in LR.

The expression changes of genes associated with protein metabolism, folding, transport, localizati on and assembly during rat liver regeneration.

To study the expression and function of protein metabolism, folding, transport, localization and assembly-associated genes in rat liver regeneration (LR) at transcriptional level, we obtained above genes from databases and scientific articles, detected their expression profiles in rat LR using Rat Genome 230 2.0 array, and determined liver regeneration-associated genes by comparing the partial hepatectomy (PH) group with sham operation (SO) group. Totally 1147 genes were preliminarily confirmed to be LR-associated. The results from the chip detection demonstrated that genes involved in the above biological processes were mostly up-regulated in rat LR; protein metabolism-participating genes were initially expressed mainly at 0.5-1 h and 16-30 h following PH; protein degradation-accelerating genes outnumbered protein accumulation-promoting genes between 0.5-12 h, whereas the latter were more than the former during 16-48 hours; protein synthesis-involved genes were more frequently up-regulated at 16,24,42 and 66 h, especially at 42 h; up-regulation of protein degradation-associated genes dominated almost during the whole period of LR, especially at forepart and prophase; the up-regulated protein folding-associated genes were predominant than down-regulated at 2, 16-24, 42, 66, 72 and 168 h, especially at 66 h; protein transport and localization-associated genes were predominantly up-regulated during the whole period of LR, especially at 66 h; and most of protein complex assembly-associated genes were up-regulated before 96 h, especially at 12 h. it was inferred according to the above analysis that protein synthesis was enhanced at metaphase of LR, and the activities of protein degradation, folding, transport, localization and assembly were vigorous almost during the whole period of LR.

[Expression profiles of the extracellular matrix-associated genes during rat liver regeneration].

It has been well known that the extracellular matrix (ECM) plays an important role in cell polarization, cell adhesion, cell proliferation, morphogenesis and differentiation. For the sake of the further in-depth investigation of the changes and actions of ECM in liver regeneration (LR) at gene transcriptional level, the ECM-associated genes were obtained by databases searching and literature retrieving, subsequently their expression profiles in rat regenerating liver were detected using Rat Genome 230 2.0 array, then LR-associated genes were identified based on comparison of the gene expression difference between sham operation (SO) group and partial hepatectomy (PH) group. A total of 97 genes were verified to be LR-associated. The initially and totally expressed number of these genes occurring in initial phase of LR, G0/G1 transition, cell proliferation, cell differentiation and structure-functional reconstruction were 49, 19, 43, 5 and 84, 51, 369, 144, respectively, illustrating that expression of the ECM-associated genes were initiated mainly in the early phase, working in differ-ent phases. Their expression similarity was classified into 5 groups including only up-, predominantly up-, only down-, predominantly down-, and equal in up-regulated and down-regulated, involving 38, 21, 21, 10 and 7 genes, respectively; the number of up-regulated expressed genes and down-regulated expressed ones was 411 and 186; their expression patterns were categorized into 24 types, showing that the physiological and biochemical activities in LR were characterized by phase, diversity and intricacy. According to expression profiles and expression patterns of the ECM-associated genes in LR, it was confirmed that the levels of the below-listed genes in expression increased at the corresponding phases of LR, including fibronectin-associated genes at early phase in LR, and collagen-associated genes at middle phase.