👤 Linbo Guan

The genetic background of hepatocellular carcinoma (HCC) has yet to be completely understood. Here, we describe the application of suppression subtractive hybridization (SSH) coupled with cDNA microarray analysis for the isolation and identification of differential expression of genes in HCC. Twenty-six known genes were validated as up-regulated and 19 known genes as down-regulated in HCC. The known genes identified were found to have diverse functions. In addition to the overexpression of AFP, these genes (increased in the presence of HCC) are involved in many processes, such as transcription and protein biosynthesis (HNRPDL, PABPC1, POLR2K, SRP9, SNRPA, and six ribosomal protein genes including RPL8, RPL14, RPL41, RPS5, RPS17, RPS24), the metabolism of lipids and proteins (FADS1, ApoA-II, ApoM, FTL), cell proliferation (Syndecan-2, and Annexin A2), and signal transduction (LRRC28 and FMR1). Additionally, a glutathione-binding protein involved in the detoxification of methylglyoxal known as GLO1 and an enzyme which increases the formation of prostaglandin E(2) known as PLA2G10 were up-regulated in HCC. Among the underexpressed genes discovered in HCC, most were responsible for liver-synthesized proteins (fibrinogen, complement species, amyloid, albumin, haptoglobin, hemopexin and orosomucoid). The enzyme implicated in the biotransformation of CYP family members (LOC644587) was decreased. The genes coding enzymes ADH1C, ALDH6A1, ALDOB, Arginase and CES1 were also found. Additionally, we isolated a zinc transporter (Zip14) and a function-unknown gene named ZBTB11 (Zinc finger and BTB domain containing 11) which were underexpressed, and seven expression sequence tags deregulated in HCC without significant homology reported in the public database. Essentially, by using SSH combined with a cDNA microarray we have identified a number of genes associated with HCC, most of which have not been previously reported. Further characterization of these differentially expressed genes will provide information useful in understanding the genes responsible for the development of HCC. Show less

Embryonic organs attain their final dimensions through the generation of proper cell number and size, but the control mechanisms remain obscure. Here, we establish Gridlock (Grl), a Hairy-related basic helix-loop-helix (bHLH) transcription factor, as a negative regulator of cardiomyocyte proliferative growth in zebrafish embryos. Mutations in grl cause an increase in expression of a group of immediate-early growth genes, myocardial genes, and development of hyperplastic hearts. Conversely, cardiomyocytes with augmented Grl activity have diminished cell volume and fail to divide, resulting in a marked reduction in heart size. Both bHLH domain and carboxyl region are required for Grl negative control of myocardial proliferative growth. These Grl-induced cardiac effects are counterbalanced by the transcriptional activator Gata5 but not Gata4, which promotes cardiomyocyte expansion in the embryo. Biochemical analyses show that Grl forms a complex with Gata5 through the carboxyl region and can repress Gata5-mediated transcription via the bHLH domain. Hence, our studies suggest that Grl regulates embryonic heart growth via opposing Gata5, at least in part through their protein interactions in modulating gene expression. Show less