Podocin-rtTA (Tg(NPHS2-rtTA2*M2)1Jbk Mouse
Mutant Mouse: The tet transactivator (rtTA) gene placed under the control of the human NPHS2 gene).
Reverse tetracycline-controlled transgenic mouse model (Tet-On) under the control of the specific promoter for the glomerular podocyte protein (Podocin, NPHS2).
Podocytes are post-mitotic epithelial cells that are positioned on the exterior aspect of the glomerular capillary wall and contribute to the selective molecular permeability of glomeruli. Podocyte damage or dysfunction results in loss of the characteristic foot processes that normally interdigitate and form the selective permeability barriers composed of filtration slits bridged by slit diaphragms. Minimal damage causes proteinuria that, in the case of minimal change disease (MCD), can be reversed by steroid treatment. In focal segmental glomerulosclerosis, more severe loss of podocytes ultimately results in glomerulosclerosis.
The transgenic mouse model described uses a tetracycline controlled reporter-operator system from E. coli to induce the transcription of a target gene in podocytes. Transcription is induced only in podocytes and only when tetracycline is administered. The response is dependent on the tetracycline dose. The podocyte-specific inducible transgene system can be used to identify factors that exacerbate or ameliorate podocyte injury, and can be used to express Cre-recombinase.
In the reverse tetracycline-controlled transcriptional activator system (rtTA), transcription in podocytes is activated by a transgene expressing a chimeric protein containing: (i) the promoter-enhancer region of Nphs2 (podocin, a protein specifically expressed in the podocyte), (ii) a Tet repressor domain that only binds to and activates the tetracycline operator sequence (TetO) when it binds tetracycline, and (iii) a VP16 activation domain. The target gene to be induced is linked to the tetracycline operator (TetO).