Expressed genes in regenerating rat liver after partial hepatectomy

AIM: To reveal the liver regeneration (LR) and its controlas well as the occurrence of liver disease and to study the gene expression profiles of 551 genes after partial hepatectomy (PH) in regenerating rat livers.METHODS: Five hundred and fifty-one expressed sequence tags screened by suppression subtractive hybridization were made into an in-house cDNA microarray, and the expressive genes and their expressive profiles in regenerating rat livers were analyzed by microarray and bioinformatics. RESULTS: Three hundred of the analyzed 551 genes were up- or downregulated more than twofolds at one or more time points during LR. Most of the genes were up- or downregulated 2-5 folds, but the highest reached 90 folds of the control. One hundred and thirty-nine of themshowed upregulation, 135 displayed downregulation, and up or down expression of 26 genes revealed a dependence on regenerating livers. The genes expressedin 24-h regenerating livers were much more than those in the others. Cluster analysis and generalization analysis showed that there were at least six distinct temporal patterns of gene expression in the regenerating livers, that is, genes were expressed in the immediate early phase, early phase, intermediate phase, early-late phase, late phase, terminal phase. CONCLUSION: In LR, the number of down-regulated genes was almost similar to that of the upregulated genes; the successively altered genes were more than the rapidly transient genes. The temporal patterns of gene expression were similar 2 and 4 h, 12 and 16 h, 48 and 96 h, 72 and 144 h after PH. Microarray combined with suppressive subtractive hybridization can effectively identify the genes related to LR.

Cloning and analysizing the up-regulated expression of transthyretin-related gene (LR_1) in rat liver regeneration following short interval successive partial hepatectomy

AIM: Cloning and analysizing the up-regulated expressionof transthyretin-related gene following short intervalsuccessive partial hepatectomy (SISPH) to elucidate themechanism of differentiation, division, dedifferentiation andredifferentiation in rat liver regeneration (LR).METHODS: Lobus external sinister and lobus centralissinister, lobus centralis, lobus dexter, lobus candatus wereremoved one by one from rat liver at four different time points4, 36, 36 and 36 hr (total time: 4 hr, 40 hr, 76 hr, 112 hr)respectively. Suppression subtractive hybridization (SSH) wascarried out by using normal rat liver tissue as driver and thetissue following short interval successive partial hepatectomy(SISPH) as tester to construct a highly efficient forward-subtractive cDNA library. After screening, an interested ESTfragment was selected by SSH and primers were designedaccording to the sequence of the EST to clone the full-lengthcDNA fragment using RACE (rapid amplification of cDNAend). Homologous detection was performed between thefull-lenth cDNA and Genbank.RESULTS: Forward suppression subtractive hybridization(FSSH) library between 0 h and 112 h following SISPH wasconstructed and an up-regulated full-length cDNA (namedLR1), which was related with the transthyretin gene, wascloned by rapid amplification of cDNA end. It was suggestedthat the gene is involved in the cellular dedifferentiation inLR following SISPH.CONCLUSION: Some genes were up-regulated in 112 hfollowing SISPH in rat. LR1 is one of these up-regulatedexpression genes which may play an important role in rat LR.

Isolation and analysis of a novel gene over-expressed during liver regeneration

AIM: To isolate and analyze a novel gene over-expressed during liver regeneration. METHODS: Total RNA of regenerating liver was extracted from liver tissue after 0-4-36-36-36 hr short interval successive partial hepatectomy (SISPH). Reverse transcription-polymerase chain reaction was used to synthesize double strand cDNA, after the tissue was digested by proteinase K and Sfi A/B. The double-strand cDNA was ligated to λTriplEx2.λphage packaging reaction was performed and E. coli XL1-Blue was infected for titering and amplifying. One expressed sequence tag was probed by Dig and phagein situ hybridization was carried out to isolate positive clones. Positive recombinant λTriplEx2 was converted to the corresponding pTriplEx2, and bioinformatics was used to analyze full-length cDNA. RESULTS: We isolated a novel full-length cDNA during liver regeneration following SISPH.CONCLUSION: We have succeeded in cloning a novel gene,based on bioinformatics. We postulate that this gene may function in complicated network in liver regeneration. On the one hand, it may exert initiation of liver regeneration via regulating nitric oxide synthesis. On the other hand, it may protect damaged residue lobus following SISPH.

Identification of expressed genes in regenerating rat liver in 0-4-8-12 h short interval successive partial hepatectomy

AIM: To identify the genes differentially expressed in the regenerating rat liver of 0-4-8-12 h short interval successive partial hepatectomy (SISPH) and to analyze their expression profiles.METHODS: Five hundred and fifty-one elements screened from subtractive cDNA libraries were made into a cDNA microarray (cDNA chip). Extensive gene expression analysis following 0-4-8-12 h SISPH was conducted by microarray.RESULTS: One hundred and eighty-three elements were selected, which were either up- or down-regulated more than 2-fold at one or more time points after SISPH. Cluster analysis and generalization analysis showed that there were five distinct temporal patterns of gene expression.Eighty-six genes were unreported, associated with liver regeneration (LR).CONCLUSION: Microarray analysis shows that the down regulated genes are much more than the up-regulated ones in SISPH; the numbers of genes expressed consistently are fewer than that expressed immediately; the genes expressed in high abundance are much fewer than that increased 2-5-fold. The comparison of SISPH with partial hepatectomy (PH) shows that the expression trends of most genes in SISPH and in PH are similar,but the expression of 43 genes is specifically altered in SISPH.

Gene expression differences of regenerating rat liver in a short interval successive partial hepatectomy

AIM: To identify the genes expressed differentially in the regenerating rat liver in a short interval successive partial hepatectomy (SISPH), and to analyze their expression profiles.METHODS: Five hundred and fifty-one elements selected from subtractive cDNA libraries were conformed to a cDNA microarray (cDNA chip). An extensive gene expression analysis following 0-36-72-96-144 h SISPH was performed by microarray.RESULTS: Two hundred and sixteen elements were identified either up- or down-regulated more than 2-fold at one or more time points of SISPH. By cluster analysis and generalization analysis, 8 kinds of ramose gene expression clusters were generated in the SISPH. Of the 216 elements,111 were up-regulated and 105 down-regulated. Except 99 unreported genes, 117 reported genes were categorized into 22 groups based on bheir biological functions. Comparison of the gene expression in SISPH with that after partial hepatectomy (PH) disclosed that 56 genes were specially altered in SISPH, and 160 genes were simultaneously upregulated or down-regulated in SISPH and after PH, but in various amount and at different time points.CONCLUSION: Genes expressed consistently are far less than that intermittently, the genes strikingly increased are much less than that increased only 2-5 fold; the expression trends of most genes in SISPH and in PH are similar, but the expression of 56 genes is specifically altered in SISPH.Microarray combined with suppressive subtractive hybridization can in a large scale effectively identify the genes related to liver regeneration.