Project description:Dr. Liu's research group is interested in studying the expression and functions of galectin-3, -7 and -12, in particular the roles of these proteins in inflammation and neoplasm. Members of the galectin family are known to participate in cellular homeostasis by modulating cell growth, controlling cell cycle progression, and inducing or inhibiting apoptosis. It is known that some galectins have similar functions. However, it is not fully understood whether they work cooperatively or not. As the outermost barrier of the body, skin is directly and frequently exposed to a prooxidative environment, including solar ultraviolet A (UVA), ultraviolet B (UVB) radiation, and air pollution. Several reports have shown that exposure of cells to UV increase or decrease the levels of galectins. For example, the amounts of galectin-7 mRNA and protein are increased rapidly after UVB irradiation of keratinocytes (Proc. Natl. Acad. Sci. USA 1999; 96:11329-34). Heat shock and subculturing decrease, while alkylating agents and UV-light increase galectin-3 (Cell Physiol Biochem 2000; 10:149-58). To analyze the change of all galectin gene expression profiles after UVB irradiation and to determine the presence or absence of coordinate regulation, we analyzed the gene expression profiles of keratinocytes exposed to UVB. Normal human epidermal keratinocytes (NHEK) were irradiated with 200 J/m2 of UVB. Total RNA will be extracted at 0, 6, 12 and 24 h after irradiation (duplicate) for analysis on the Glyco gene chip. Several reports have shown that exposure to UV light can regulate levels of galectin in skin. This study seeks to analyze the changes in all galectin gene expression profiles post-UVB irradiation to determine the presence or absence of coordinate regulation. In this study, normal human keratinocytes were irradiated with 200J/m2 of UVB. Total RNA was extracted at 0, 6, 12, and 24-hour post irradiation time points, in duplicate. Samples were hybridized and analyzed using the GLYCOv2 array.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:Dr. Liu's research group is interested in studying the expression and functions of galectin-3, -7 and -12, in particular the roles of these proteins in inflammation and neoplasm. Members of the galectin family are known to participate in cellular homeostasis by modulating cell growth, controlling cell cycle progression, and inducing or inhibiting apoptosis. It is known that some galectins have similar functions. However, it is not fully understood whether they work cooperatively or not. As the outermost barrier of the body, skin is directly and frequently exposed to a prooxidative environment, including solar ultraviolet A (UVA), ultraviolet B (UVB) radiation, and air pollution. Several reports have shown that exposure of cells to UV increase or decrease the levels of galectins. For example, the amounts of galectin-7 mRNA and protein are increased rapidly after UVB irradiation of keratinocytes (Proc. Natl. Acad. Sci. USA 1999; 96:11329-34). Heat shock and subculturing decrease, while alkylating agents and UV-light increase galectin-3 (Cell Physiol Biochem 2000; 10:149-58). To analyze the change of all galectin gene expression profiles after UVB irradiation and to determine the presence or absence of coordinate regulation, we analyzed the gene expression profiles of keratinocytes exposed to UVB. Normal human epidermal keratinocytes (NHEK) were irradiated with 200 J/m2 of UVB. Total RNA will be extracted at 0, 6, 12 and 24 h after irradiation (duplicate) for analysis on the Glyco gene chip.
Project description:Gene methylation profiling of immortalized human mesenchymal stem cells comparing HPV E6/E7-transfected MSCs cells with human telomerase reverse transcriptase (hTERT)- and HPV E6/E7-transfected MSCs. hTERT may increase gene methylation in MSCs. Goal was to determine the effects of different transfected genes on global gene methylation in MSCs.