New mouse lines for the analysis of neuronal morphology using CreER(T)/loxP-directed sparse labeling.
BACKGROUND
Pharmacologic control of Cre-mediated recombination using tamoxifen-dependent activation of a Cre-estrogen receptor ligand binding domain fusion protein [CreER(T)] is widely used to modify and/or visualize cells in the mouse.


RESULTS
We describe here two new mouse lines, constructed by gene targeting to the Rosa26 locus to facilitate Cre-mediated cell modification. These lines should prove particularly useful in the context of sparse labeling experiments. The R26rtTACreER line provides ubiquitous expression of CreER under transcriptional control by the tetracycline reverse transactivator (rtTA); dual control by doxycycline and tamoxifen provides an extended dynamic range of Cre-mediated recombination activity. The R26IAP line provides high efficiency Cre-mediated activation of human placental alkaline phosphatase (hPLAP), complementing the widely used, but low efficiency, Z/AP line. By crossing with mouse lines that direct cell-type specific CreER expression, the R26IAP line has been used to produce atlases of labeled cholinergic and catecholaminergic neurons in the mouse brain. The R26IAP line has also been used to visualize the full morphologies of retinal dopaminergic amacrine cells, among the largest neurons in the mammalian retina.


CONCLUSIONS
The two new mouse lines described here expand the repertoire of genetically engineered mice available for controlled in vivo recombination and cell labeling using the Cre-lox system.
Badea
Tudor C
TC
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. tbadea@mail.jhmi.edu
Hua
Zhong L
ZL
Smallwood
Philip M
PM
Williams
John
J
Rotolo
Thomas
T
Ye
Xin
X
Nathans
Jeremy
J
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004318:Doxycycline / Q000494:pharmacology; D005260:Female; D005818:Genetic Engineering / Q000379:methods; D019426:Integrases / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008957:Models, Genetic; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D011995:Recombination, Genetic; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology; D015533:Transcriptional Activation; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D013629:Tamoxifen; C016601:afimoxifene; D014446:Tyrosine 3-Monooxygenase; C045073:Cre recombinase; D019426:Integrases; D000469:Alkaline Phosphatase; D004318:Doxycycline