Cuifang Chang

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. J. Cell. Biochem. 113: 229–237, 2012.

Comprehensive CircRNA expression profile and selection of key CircRNAs during priming phase of rat liver regeneration

BackgroundRat liver regeneration (LR) proceeds along a process of highly organized and ordered tissue growth in response to the loss or injury of liver tissue, during which many physiological processes may play important roles. The molecular mechanism of hepatocyte proliferation, energy metabolism and substance metabolism during rat LR had been elucidated. Further, the correlation of circular RNA (circRNA) abundance with proliferation has recently been clarified. However, the regulatory capacity of circRNA in rat LR remains a fascinating topic.ResultsTo investigate the regulatory mechanism of circRNA during priming phase of rat LR, high-throughput RNA sequencing technology was performed to unbiasedly profile the expression of circRNA during priming phase of rat LR. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) biological pathway analysis was conducted to predict the functions of differentially expressed circRNAs and their host linear transcripts. Co-expression networks of circRNA-miRNA were constructed based on the correlation analysis between the differentially expressed LR-related circRNAs and the condition of their miRNA binding sites. To excavate the key circRNAs in the early phase of rat LR, we comprehensively evaluated and integrated the relationship of expression level between the circRNAs and the linear transcripts as well as the distribution of miRNA binding sites in circRNA sequences.ConclusionsThis paper is the first to employ the comprehensive circRNA expression profile and to investigate circRNA-miRNA interactions during priming phase of rat LR. Two thousand four hundred twelve circRNAs were detected, and 159 circRNAs deriving from 116 host linear transcripts differentially expressed (p < 0.05). Six significantly changed circRNAs during priming phase of rat LR were screened as key circle molecules, and then were validated by qRT-PCR. This study will lay the foundation for revealing the functional roles of circRNAs during rat LR and help solve the remaining clinical problems.

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. J. Cell. Biochem. 112: 3194–3205, 2011.

Gene expression profiles reveal significant differences between rat liver cancer and liver regeneration.

Rapid cell proliferation and growth occur in both liver cancer (LC) and liver regeneration (LR). Does it imply that LC and LR share some similar molecular mechanisms? To elucidate the intrinsic similarities and differences between the above two processes at transcriptional level, rat models of diethylnitrosamine-induced LC and 2/3 partial hepatectomy-induced LR were separately established. Then Rat Genome 230 2.0 Array was used to detect gene expression profiles of liver tissues obtained from the above two models, and bioinformatics methods, such as hierarchical clustering, k-means clustering and Expression Analysis Systematic Explorer (EASE), were applied to uncover the correlation between gene expression changes and physiological activities in LC and LR. Subsequently expression changes of six selected genes were confirmed by real-time quantitative RT-PCR. As a result, the expressions of 909 genes were found significantly changed during LC occurrence and 948 genes in LR. The expression profiles of the above two events were extremely different, and their expression patterns were classified into 6 clusters. Based on the correlation between expression patterns and functional profiles, we found that drug/toxin metabolism and oxidation reduction were induced in LC, but decreased in LR at the transcription level, while lipid, steroid and chemical homeostasis were remarkably repressed in LC but induced in LR; inflammation/immune response and apoptosis were not obvious or weaker in LC than in LR, whereas the activities of angiogenesis and cell adhesion/migration in LC were much stronger.

Characterization of transcriptional profiling of Kupffer cells during liver regeneration in rats.

KCs (Kupffer cells), as an important hepatic immunoregulatory cells, play a key role in LR (liver regeneration). Uncovering the transcriptional profiling of KCs after PH (partial hepatectomy) would likely clarify its implication in LR. Here, we isolated KCs by methods of Percoll density gradient centrifugation and immunomagnetic beads. Transcriptional profiles of KCs were monitored up to 168 h post‐PH using microarray. By comparing the expression profile of KCs at 2–168 h post‐PH with that of the control and applying the statistical and bioinformatics criteria, we found 1407 known and 927 unknown genes related to LR. K‐means clustering analysis grouped these 1407 genes into robust 14 time‐course clusters representing distinct patterns of regulation. Based on gene‐set enrichment analysis, genes encoding products involved in cytokine signalling, inflammatory response and cell chaemotaxis were highly enriched in the cluster characterized by gradual up‐regulation and then return; genes in defence response and immune response were enriched in clusters ‘the general down‐regulation during LR’; genes in fatty acid synthesis and sterol metabolism were preferentially distributed in the cluster ‘gradual increase’; whereas genes in the categories ‘lipid catabolism’ and ‘glycolysis’ were enriched in cluster ‘decrease at two intervals’. According to the above analysis, KCs were seemingly sensitive to operative stimulus; immune defence and detoxification function of KCs obviously dropped post‐operatively; fatty acid synthesis were enhanced, whereas lipid catabolism and glycolysis were reduced after PH. This study provides a detailed in vivo gene expression profile of KCs, providing a framework to better understand the molecular mechanisms underlying the regeneration process at cellular level.

Integrative proteomic and microRNA analysis of the priming phase during rat liver regeneration

The partial hepatectomy (PH) model provides an effective medium for study of liver regeneration (LR). Considering that LR is regulated by microRNAs (miRNAs), investigation of the regulatory role of miRNAs is critical for revealing how regenerative processes are initiated and controlled. Using high-throughput sequencing technology, we examined miRNA expression profiles of the regenerating rat liver after PH, and found that 23 miRNAs were related to rat LR. Among them, several miRNAs were significantly altered at 2h and 6h after PH, corresponding to the priming phase of LR. Furthermore, we examined the protein profiles in the regenerating rat liver at 2h and 6h after PH by iTRAQ coupled with LC-MS/MS, and found that 278 proteins were significantly changed. Subsequently, an integrative proteomic and microRNA analysis by Ingenuity Pathway Analysis 9.0 (IPA) software showed that miR-125a, miR-143, miR-150, miR-181c, miR-182, miR-183, miR-199a, miR-429 regulated the priming phase of rat LR by modulating the expression of proteins involved in networks critical for cell apoptosis, cell survival, cell cycle, inflammatory response, metabolism, etc. Thus, our studies provide novel evidence for a functional molecular network populated by the down-regulated targets of the up-regulated miRNAs in the priming phase of rat LR.

Gene expression profiles predict the possible regulatory role of OPN-mediated signaling pathways in rat liver regeneration

Osteopontin (OPN; gene Spp1), as a pro-inflammatory cytokine, has a range of activities relevant to the occurrence and progression of hepatitis, liver fibrosis or liver tumors. However, little is known about the role of OPN in liver regeneration (LR). To reveal the expression profiles of OPN and its receptors and the possible regulatory role of OPN in rat LR, Rat Genome 230 2.0 was used to detect expression profiles of OPN-mediated signaling pathway-associated genes after partial hepatectomy (PH), and the results showed that 81 genes were significantly changed at mRNA level, and among which, 65 genes were up-regulated. Then, k-means clustering was employed to classify above 81 genes into 5 clusters based on gene expression similarity, and EASE analysis further indicated that the above genes were mainly associated with stress response, inflammatory response, cell activation, proliferation, adhesion and migration. Thereafter, IPA software and Western blot were used to analyze potential effects of every branch of OPN signaling pathways during LR, and the results suggested that the genes expression changes of OPN signaling pathways may account for enhanced cell proliferation, survival, adhesion and migration, augmented inflammation response and attenuated apoptosis during LR.

Analysis of the ways and methods of signaling pathways in regulating cell cycle of NIH3T3 at transcriptional level

BackgroundTo analyze the ways and methods of signaling pathways in regulating cell cycle progression of NIH3T3 at transcriptional level, we modeled cell cycle of NIH3T3 and found that G1 phase of NIH3T3 cell cycle was at 5–15 h after synchronization, S phase at 15–21 h, G2 phase at 21–22 h, M phase at 22–25 h.ResultsMouse Genome 430 2.0 microarray was used to detect the gene expression profiles of the model, and results showed remarkable changes in the expressions of 64 cell cycle genes and 960 genes associated with other physiological activity during the cell cycle of NIH3T3. For the next step, IPA software was used to analyze the physiological activities, cell cycle genes-associated signal transduction activities and their regulatory roles of these genes in cell cycle progression, and our results indicated that the reported genes were involved in 17 signaling pathways in the regulation of cell cycle progression. Newfound genes such as PKC, RAS, PP2A, NGR and PI3K etc. belong to the functional category of molecular mechanism of cancer, cyclins and cell cycle regulation HER-2 signaling in breast cancer signaling pathways. These newfound genes could promote DNA damage repairment and DNA replication progress, regulate the metabolism of protein, and maintain the cell cycle progression of NIH3T3 modulating the reported genes CCND1 and C-FOS.ConclusionAll of the aforementioned signaling pathways interacted with the cell cycle network, indicating that NIH3T3 cell cycle was regulated by a number of signaling pathways.

Genome-wide analysis of gene expression in dendritic cells from rat regenerating liver after partial hepatectomy

Dendritic cells (DCs) play a pivotal role in orchestrating immune response occurring in liver regeneration (LR). However, there are few details about relationship between DCs and LR at the molecular level. In this study, we firstly obtained high‐purity DCs by the combination of Percoll density gradient centrifugation and immunomagentic bead sorting, then measured genome‐wide gene expression in DCs from rat regenerating liver after partial hepatectomy (PH) using rat genome 230 2·0 microarray composed of 25 020 genes, and verified the reliability of microarray data with RT‐PCR method. Among 25 020 genes present on the array, 1621 known genes and 1307 unknown genes, totally 2928 genes, were identified to be LR‐related. H‐clustering analysis showed that 2928 genes were grouped into three expression patterns: up‐regulation, down‐regulation and complex changes in expression. And 1621 known genes were functionally grouped into at least 23 biological categories. When expression patterns were combined with gene functions, as a whole, the genes involved in immune/defence response, inflammatory response and secretion of active substance in DCs were highly enriched in down‐regulated pattern. DCs exhibited the reduced immune/defence and inflammatory response, and the suppressed secretion capacity of active substances after PH. A further analysis of genes expressed in the phase‐dependent manner during LR suggested the rapid induction of genes encoding some transcription factors and cytokines in DCs at immediate‐early phase, the unobvious enhancement of metabolic process, immunity and inflammation at proliferation phase, while the impairment of detoxification, immunity and inflammation at terminal phase. Copyright

Serine peptidase inhibitor Kazal type I (SPINK1) promotes BRL-3A cell proliferation via p38, ERK, and JNK pathways

Serine peptidase inhibitor Kazal type I (SPINK1) has the similar spatial structure as epidermal growth factor (EGF); EGF can interact with epidermal growth factor receptor (EGFR) to promote proliferation in different cell types. However, whether SPINK1 can interact with EGFR and further regulate the proliferation of hepatocytes in liver regeneration remains largely unknown. In this study, we investigated the role of SPINK1 in a rat liver hepatocyte line of BRL‐3A in vitro. The results showed the upregulation of endogenous Spink1 (gene addition) significantly increased not only the cell viability, cell numbers in S and G2/M phase, but also upregulated the genes/proteins expression related to cell proliferation and anti‐apoptosis in BRL‐3A. In contrast, the cell number in G1 phase and the expression of pro‐apoptosis‐related genes/proteins were significantly decreased. The similar results were observed when the cells were treated with exogenous rat recombinant SPINK1. Immunoblotting suggested SPINK1 can interact with EGFR. By Ingenuity Pathway Analysis software, the SPINK1 signalling pathway was built; the predicted read outs were validated by qRT‐PCR and western blot; and the results showed that p38, ERK, and JNK pathways‐related genes/proteins were involved in the cell proliferation upon the treatment of endogenous Spink1 and exogenous SPINK1. Collectively, SPINK1 can associate with EGFR to promote the expression of cell proliferation‐related and anti‐apoptosis‐related genes/proteins; inhibit the expression of pro‐apoptosis‐related genes/proteins via p38, ERK, and JNK pathways; and consequently promote the proliferation of BRL‐3A cells. For the first time, we demonstrated that SPINK1 can associate with EGFR to promote the proliferation of BRL‐3A cells via p38, ERK, and JNK pathways. This work has direct implications on the underlying mechanism of SPINK1 in regulating hepatocytes proliferation in vivo and liver regeneration after partial hepatectomy.