Directed expression of transgenes to alveolar type I cells in the mouse.
Podoplanin (RTI40, aggrus, T1alpha, hT1alpha-2, E11, PA2.26, RANDAM-2, gp36, gp38, gp40, OTS8) is a type I cell marker in rat lung. We show that a bacterial artificial chromosome vector containing the rat podoplanin gene (RTIbac) delivers a pattern of transgene expression in lung that is more restricted to mouse type I cells than that of the endogenous mouse podoplanin gene. RTIbac-transgenic mice expressed rat podoplanin in type I cells; type II cells, airways, and vascular endothelium were negative. A modified bacterial artificial chromosome containing internal ribosome entry site (IRES)-green fluorescent protein (GFP) sequences in the podoplanin 3'UTR expressed rat podoplanin and transgenic GFP in type I cells. RTIbac transgene expression was absent or reduced in pulmonary pleura, lymphatic endothelium, and putative lymphoid-associated stromal tissue, all of which contained abundant mouse podoplanin. Rat podoplanin mRNA levels in normal rat lung and RTIbac transgenic lung were 25-fold higher than in corresponding kidney and brain samples. On Western blots, transgenic rat and endogenous mouse podoplanin displayed very similar patterns of protein expression in various organs. Highest protein levels were observed in lung with 10- to 20-fold less in brain; there were low levels in thymus and kidney. Both GFP and rat podoplanin transgenes were expressed at extrapulmonary sites of endogenous mouse podoplanin gene expression, including choroid plexus, eye ciliary epithelium, and renal glomerulus. Because their pulmonary expression is more restricted than endogenous mouse podoplanin, RTIbac derivatives should be useful for mouse type I cell-specific transgene delivery.
Vanderbilt
Jeff N
JN
Cardiovascular Research Institute, University of California San Francisco, San Francisco, California 94118, USA. jeff.vanderbilt@ucsf.edu
Allen
Lennell
L
Gonzalez
Robert F
RF
Tigue
Zachary
Z
Edmondson
Jess
J
Ansaldi
Daniel
D
Gillespie
Anne Marie
AM
Dobbs
Leland G
LG
D000818:Animals; D001483:Base Sequence; D022202:Chromosomes, Artificial, Bacterial; D017931:DNA Primers; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000096:biosynthesis; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D051379:Mice; D008822:Mice, Transgenic; D011650:Pulmonary Alveoli / Q000378:metabolism*; D051381:Rats; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019076:Transgenes; D000098853:Podoplanin
D017931:DNA Primers; D049452:Green Fluorescent Proteins; D008562:Membrane Glycoproteins; C092025:Pdpn protein, rat; D000098853:Podoplanin