Stable high-level gene expression in mammalian cells by T7 phage RNA polymerase.
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Biomedical subjects
Publications and source records attributed to S Bähring.
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The main core protein and segments of envelope proteins of bovine leukaemia virus fused to MS2 polymerase were expressed in E. coli. The synthesis rate varied between 3 and 25% of the total cellular proteins. BLV-MS2 polymerase fusion proteins were detected immunologically using rabbit anti-BLV sera, monoclonal antibodies and a serum of a BLV-infected cow.
Plasmids were constructed by the use of pEX vectors that encode and express different parts of the bovine leukemia virus (BLV): main core protein p24, nucleic acid-binding protein p12, transmembrane protein gp30, and different segments of envelope protein gp51. Expression of fusion proteins with molecular weights higher than 117 kD for all recombinant plasmids was shown in Coomassie-blue stained gels and by Western blot analysis with rabbit anti-BLV sera. Coupling of a gp51-encoding with a p24-encoding DNA fragment in pEX vectors led to synthesis of a fusion protein that was recognized by monoclonal antibodies directed against gp51 and p24 epitopes. Using another vector, a gp51-encoding DNA fragment of BLV was expressed as a fusion protein with 100 amino acids of the MS2 polymerase. The fusion protein was recognized by monoclonal antibodies directed against gp51.
Familial hypercholesterolemia (FH) is an autosomal-dominant inherited disorder characterized by high serum low-density lipoprotein (LDL)-cholesterol concentrations, xanthoma formation, and premature atherosclerosis. Homozygous individuals die of vascular disease as children or young adults; heterozygous persons are at high risk for premature cardiovascular death. Mutations in the LDL-receptor gene are responsible for FH. We studied 49 members of a consanguineous Syrian kindred containing 6 homozygous individuals from the same pedigree. Half of the homozygotes had giant xanthomas, while half did not, even though their LDL-cholesterol concentrations were elevated to similar degrees (> 14 mmol/l). Heterozygous FH individuals from this family were also clearly distinguishable with respect to xanthoma size. We performed DNA analysis and were successful in identifying a hitherto not described mutation in this family's LDL receptor. DNA sequence analysis of the LDL-receptor gene revealed a T to C substitution at nucleotide 1,999 in codon 646 of exon 14. We next conducted a segregation analysis, which suggests that a susceptibility gene may explain the formation of giant xanthomas in this family. We raise the hypothesis that the appearance of giant xanthomas in this FH family is controlled by a second gene acting in an autosomal-dominant or recessive fashion. Elucidation of this 'xanthoma' gene may shed additional light on LDL-cholesterol deposition.