title: Two gene fragments that direct podocyte-specific expression in transgenic mice.
abstract: Transgenic manipulation of the glomerular visceral epithelial cell offers a powerful approach for studying the biology of this morphologically complex cell type. It has been previously demonstrated that an 8.3-kb and a 5.4-kb fragment of the murine Nphs1 (nephrin) promoter-enhancer drives lacZ expression in podocytes, brain, and pancreas of transgenic mice, recapitulating the expression pattern of the endogenous nephrin gene. In this present study, two truly podocyte-specific promoters were identified that drive transgene expression in podocytes without expression in extrarenal tissues in adult or embryonic mice. A 1.25-kb fragment driving a lacZ reporter gene (p1.25N-nlacF) was derived from murine Nphs1 promoter similar to a human NPHS1 promoter fragment previously reported. Transgenic mice were generated and beta-galactosidase (beta-gal) expression was analyzed. Four of twelve founder mice were found to express beta-gal in podocytes (33% penetrance). Expression in brain and pancreas was absent in all animals, suggesting that nephrin expression in these organs might be driven by distinct cis-regulatory elements that can be removed to obtain podocyte-specific expression. A 2.5-kb fragment derived from the human NPHS2 (podocin) gene was designed in a similar fashion to drive lacZ expression in transgenic mice (p2.5P-nlacF). Twelve of twlve NPHS2 mouse founder lines expressed beta-gal exclusively in podocytes (100% penetrance). Beta-gal activity was not observed extrinsic to the kidney in p1.25N-nlacF or p2.5P-nlacF mouse embryos at gestational time points between 8.5 d post coitus and birth. In conclusion, the 2.5-kb NPHS2 promoter fragment may be useful for podocyte-specific transgenic expression when extrarenal expression of a transgene is problematic.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109-0676, USA.
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Moeller
authors.forename: Silja K
authors.initials: SK
authors.lastname: Sanden
authors.forename: Abdulsalam
authors.initials: A
authors.lastname: Soofi
authors.forename: Roger C
authors.initials: RC
authors.lastname: Wiggins
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Holzman
mesh_terms: D000818:Animals; D019556:COS Cells; D005314:Embryonic and Fetal Development; D004847:Epithelial Cells / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D007678:Kidney Glomerulus / Q000166:cytology* / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D008822:Mice, Transgenic; D009928:Organ Specificity; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics*; D019076:Transgenes
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C407223:NPHS2 protein; D011506:Proteins; C113267:nephrin