植物生物技术在生物制药中的作用3.ppt

(块根/块茎）储藏器官特异启动子 human insulin-like growth factor-1=hIGF-1，人胰岛素样生长因子-1 a single-chain peptide of 70 amino acid residues sharing 50% homology with human insulin. Synthesis of hIGF-1: Mainly in the liver and regulated by several factors such as human growth hormones and insulin. Main functions of hIGF-1: 1 Being essential for normal fetal growth and development; 2 Stimulating proliferation and survival of many cell types; 3 Promoting differentiation of a limited cell types. The clinical importance of hIGF-1 hIGF-1 can increase insulin sensitivity and possesses hypoglycemic effects similar to insulin, so hIGF-1 may become a substitute therapeutic agent for the people whose insulin receptors have functional defects, especially for those who have one or more of the following problems: 1. Growth hormone-sensitive (Laron-type) syndrome; 2. Type A insulin resistance syndrome ; 3. Diabetes; 4. Osteoporosis; 5. Acquired immunodeficiency syndrome (AIDS). The demand for hIGF-1 is likely to increase in the future. Production of hIGF-1 Recombinant hIGF-1(rthIGF-1) has been expressed in several different host–vector systems: In yeast: 8 to 55 mg/L culture (Vai et al, 2000); In E. coli: 8.5 g/L culture, but almost all the IGF-1 were not soluble (in aggregates) (Joly et al., 1998) ; In transgenic rabbits: a homozygous offspring produced 678 mg /L milk (Zinovieva et al., 1998). Limitations in the present systems expressing hIGF-1: 1. Not soluble in bacteria; 2. Formation of non-native proteins having different biological activities in yeast; 3. Transgene induced instability of certain cell lines in mammalian cell cultures; 4. Contamination of animal-based products with human pathogens in mammalian cell cultures; 5. High costs of mammalian cell cultures. Potential advantages of expressing recombinant proteins in plants: 1. Minimal risk of c