Effect of posttranscriptional regulatory elements on transgene expression and virus production in the context of retrovirus vectors.
Ineffective transgene expression in a sufficient amount of target cells is still a limitation in retroviral vector mediated gene therapy. Thus, we systematically evaluated four genetic modulators, (i) the woodchuck posttranscriptional regulatory element (WPRE), (ii) the mouse RNA transport element (RTE), (iii) the constitutive transport element (CTE) of the simian retrovirus type 1 (SRV-1), and (iv) the 5' untranslated region of the human heat shock protein 70 (Hsp70 5'UTR), all of them involved in the posttranscriptional control of mRNA nucleo/cytoplasmatic transport, RNA stability, and translation efficiency, in an MLV-based retrovirus vector context. Insertion of the WPRE into the retrovirus vector resulted in enhancement of transgene expression (EGFP) both in transfected virus producing cells as well as in infected recipient cells irrespective of the location in the vector. The best effect was observed with two copies of the WPRE, 3' of the transgene and in the 3' untranslated region of the vector backbone. However, oligomerization of this element does not further increase transgene expression. Presence of the WPRE resulted also in an increase in virus production. Introduction of the CTE and/or RTE in the retroviral vector did not alter transgene expression and infectious particle production. Positive effects were observed only in vectors harboring the CTE and/or RTE in combination with the WPRE. The activity of the Hsp70 5'UTR as a translational enhancer was found to be negligible in the context of the retroviral vector. However, interference of the Hsp70 5'UTR strong secondary structure with the packaging sequence of the viral RNA was experimentally excluded as being the cause of this. These data suggest that only the WPRE is a suitable element for the improvement of transgene expression and oncoretroviral vector production.
Hlavaty
Juraj
J
Research Institute of Virology and Biomedicine, University of Veterinary Medicine, A-1210 Vienna, Austria.
Schittmayer
Matthias
M
Stracke
Anika
A
Jandl
Gerrit
G
Knapp
Elzbieta
E
Felber
Barbara K
BK
Salmons
Brian
B
Günzburg
Walter H
WH
Renner
Matthias
M
D020121:5' Untranslated Regions; D000818:Animals; D002460:Cell Line; D003587:Cytomegalovirus / Q000235:genetics; D015870:Gene Expression; D005809:Genes, Regulator; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D009052:Leukemia Virus, Murine / Q000235:genetics; D008392:Marmota; D016093:Mason-Pfizer monkey virus / Q000235:genetics; D051379:Mice; D018146:Muromegalovirus / Q000235:genetics; D041681:NIH 3T3 Cells; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics; D012190:Retroviridae / Q000235:genetics* / Q000502:physiology*; D014779:Virus Replication
D020121:5' Untranslated Regions; D018840:HSP70 Heat-Shock Proteins; D011994:Recombinant Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins