title: Enhanced delivery of human growth hormone across cell membrane by Tat-PTD.
abstract: In this study, we utilized the HIV protein Tat protein transduction domain (Tat-PTD) to enhance the intestinal absorption of recombinant human growth hormone (rhGH) delivered by oral administration. Insulin-like growth factor 1 (IGF-1), the key factor in the GH signal transduction pathway, was differentially affected at the mRNA level by various concentrations of rhGH. At high rhGH concentrations (500 ng/ml), IGF-1 was downregulated, while low concentrations (5 ng/ml) caused IGF-1 upregulation. The addition of Tat-PTD had a significant facilitating effect on rhGH. Frozen tissue sections visualized with fluorescence microscopy, cultured cells visualized by confocal microscopy and flow cytometry all confirmed that rhGH fused to Tat-PTD demonstrated more intracellular fluorescent signal when compared to rhGH alone. ELISA showed that after 2 h of incubation, Tat-rhGH levels in the rat intestinal cavity were 1.38-fold higher than rhGH. These data indicated that Tat-PTD effectively improved the internalization of rhGH and enhance the signal transduction of rhGH, possibly laying a solid foundation for the novel oral administration of rhGH.
authors.affiliation: State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, People's Republic of China.
authors.forename: Yawen
authors.initials: Y
authors.lastname: Ni
authors.forename: Jingyou
authors.initials: J
authors.lastname: Yu
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Xu
authors.forename: Xiao-Lin
authors.initials: XL
authors.lastname: Meng
mesh_terms: D000818:Animals; D000906:Antibodies / Q000032:analysis; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D016503:Drug Delivery Systems; D015696:Gene Products, tat / Q000494:pharmacology*; D019382:Human Growth Hormone / Q000008:administration & dosage* / Q000378:metabolism / Q000627:therapeutic use*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000235:genetics; D019169:Jurkat Cells; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011817:Rabbits; D011994:Recombinant Proteins
chemical_list: D000906:Antibodies; D015696:Gene Products, tat; D012333:RNA, Messenger; D011994:Recombinant Proteins; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I