Efficient delivery of Cre-recombinase to neurons in vivo and stable transduction of neurons using adeno-associated and lentiviral vectors.
BACKGROUND
Inactivating genes in vivo is an important technique for establishing their function in the adult nervous system. Unfortunately, conventional knockout mice may suffer from several limitations including embryonic or perinatal lethality and the compensatory regulation of other genes. One approach to producing conditional activation or inactivation of genes involves the use of Cre recombinase to remove loxP-flanked segments of DNA. We have studied the effects of delivering Cre to the hippocampus and neocortex of adult mice by injecting replication-deficient adeno-associated virus (AAV) and lentiviral (LV) vectors into discrete regions of the forebrain.


RESULTS
Recombinant AAV-Cre, AAV-GFP (green fluorescent protein) and LV-Cre-EGFP (enhanced GFP) were made with the transgene controlled by the cytomegalovirus promoter. Infecting 293T cells in vitro with AAV-Cre and LV-Cre-EGFP resulted in transduction of most cells as shown by GFP fluorescence and Cre immunoreactivity. Injections of submicrolitre quantities of LV-Cre-EGFP and mixtures of AAV-Cre with AAV-GFP into the neocortex and hippocampus of adult Rosa26 reporter mice resulted in strong Cre and GFP expression in the dentate gyrus and moderate to strong labelling in specific regions of the hippocampus and in the neocortex, mainly in neurons. The pattern of expression of Cre and GFP obtained with AAV and LV vectors was very similar. X-gal staining showed that Cre-mediated recombination had occurred in neurons in the same regions of the brain, starting at 3 days post-injection. No obvious toxic effects of Cre expression were detected even after four weeks post-injection.


CONCLUSIONS
AAV and LV vectors are capable of delivering Cre to neurons in discrete regions of the adult mouse brain and producing recombination.
Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK. Bushra.Ahmed@ucl.ac.uk
Bushra Y
BY
Ahmed
Sridhara
S
Chakravarthy
Ruben
R
Eggers
Wim T J M C
WT
Hermens
Jing Ying
JY
Zhang
Simone P
SP
Niclou
Christiaan
C
Levelt
Fred
F
Sablitzky
Patrick N
PN
Anderson
A R
AR
Lieberman
Joost
J
Verhaagen
D000818:Animals; D002460:Cell Line; D000229:Dependovirus / Q000235:genetics*; D015870:Gene Expression; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000378:metabolism / Q000821:virology; D019426:Integrases / Q000008:administration & dosage* / Q000235:genetics* / Q000378:metabolism; D016086:Lentivirus / Q000235:genetics*; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D019579:Neocortex / Q000378:metabolism / Q000821:virology; D009474:Neurons / Q000378:metabolism* / Q000821:virology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic / Q000187:drug effects / Q000235:genetics; D019076:Transgenes; D014764:Viral Proteins / Q000008:administration & dosage* / Q000235:genetics* / Q000378:metabolism
D008164:Luminescent Proteins; D011994:Recombinant Proteins; D014764:Viral Proteins; D049452:Green Fluorescent Proteins; C045073:Cre recombinase; D019426:Integrases