Podocyte-specific expression of tamoxifen-inducible Cre recombinase in mice.
BACKGROUND
Podocytes play an important role in maintaining normal glomerular function. A podocyte-specific conditional knockout technology has been established by the use of transgenic mice expressing a podocyte-specific Cre recombinase to clarify the role of genes expressed in the podocytes. However, it may be difficult to examine the role of genes in certain pathologic conditions using conventional podocyte-specific knockout mice because they may be embryonically lethal or exhibit congenital renal abnormality.


METHODS
To introduce a temporal control in the genetic experiments targeting the podocyte, we constructed tamoxifen-inducible Cre recombinase (CreER(T2)) transgenic mice under the control of podocyte-specific promoter, 2.5-kb fragment of the human podocin (NPHS2) gene. The specificity and efficiency of Cre activity were examined by crossing NPHS2-CreER(T2) with the ROSA26 reporter (R26R) mouse in which a floxed-stop cassette has been placed upstream of the beta-galactosidase gene. Four-week-old double-mutant mice (NPHS2-CreER(T2)/R26R) were intraperitoneally administered with 0.5 mg of 4-hydroxytamoxifen (4-OHT) for three consecutive days.


RESULTS
NPHS2-CreER(T2)/R26R treated with 4-OHT expressed beta-galactosidase specifically in 85% of the podocytes in glomeruli. Expression of Cre recombinase mRNA was mostly restricted to the kidney, especially in glomeruli.


CONCLUSIONS
In conclusion, we have successfully generated podocyte-specific inducible Cre transgenic mice by tamoxifen administration. These mice allow us to disrupt the genes specifically in the podocytes after birth.
Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan.
Hideki
H
Yokoi
Masato
M
Kasahara
Masashi
M
Mukoyama
Kiyoshi
K
Mori
Koichiro
K
Kuwahara
Junji
J
Fujikura
Yuji
Y
Arai
Yoko
Y
Saito
Yoshihisa
Y
Ogawa
Takashige
T
Kuwabara
Akira
A
Sugawara
Kazuwa
K
Nakao
D000818:Animals; D007274:Injections, Intraperitoneal; D019426:Integrases / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D023421:Models, Animal; D050199:Podocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D022661:RNA, Untranslated; D013629:Tamoxifen / Q000008:administration & dosage / Q000494:pharmacology*; D001616:beta-Galactosidase / Q000378:metabolism
C110853:Gt(ROSA)26Sor non-coding RNA, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C407223:NPHS2 protein; D011506:Proteins; D022661:RNA, Untranslated; D013629:Tamoxifen; C045073:Cre recombinase; D019426:Integrases; D001616:beta-Galactosidase