Expression and subcellular distribution of novel glomerulus-associated proteins dendrin, ehd3, sh2d4a, plekhh2, and 2310066E14Rik.
The glomerular capillary tuft is a highly specialized microcapillary that is dedicated to function as a sophisticated molecular sieve. The glomerulus filter has a unique molecular composition, and several essential glomerular proteins are expressed in the kidney exclusively by glomerular podocytes. A catalog of >300 glomerulus-upregulated transcripts that were identified using expressed sequence tag profiling and microarray analysis was published recently. This study characterized the expression profile of five glomerulus-upregulated transcripts/proteins (ehd3, dendrin, sh2d4a, plekhh2, and 2310066E14Rik) in detail. The expression pattern of these novel glomerular transcripts in various mouse tissues was studied using reverse transcriptase-PCR, Northern blotting, and in situ hybridization. For studying the distribution of corresponding proteins, polyclonal antibodies were raised against the gene products, and Western blotting, immunofluorescence, and immunoelectron microscopic analyses were performed. Remarkably, it was discovered that all five transcripts/proteins were expressed in the kidney exclusively by glomerular cells. Ehd3 was expressed only by glomerular endothelial cells. Importantly, ehd3 is the first gene ever shown to be expressed exclusively by glomerular endothelial cells and not by other endothelial cells in the kidney. Dendrin, sh2d4a, plekhh2, and 2310066E14Rik, however, were transcribed solely by podocytes. With the use of polyclonal antibodies, dendrin, sh2d4a, and plekhh2 proteins were localized to the slit diaphragm and the foot process, whereas 2310066E14Rik protein was localized to the podocyte major processes and cell body. This study provides fresh insights into glomerular biology and uncovers new possibilities to explore the role of these novel proteins in the glomerular physiology and pathology.
Patrakka
Jaakko
J
Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden.
Xiao
Zhijie
Z
Nukui
Masatoshi
M
Takemoto
Minoru
M
He
Liqun
L
Oddsson
Asmundur
A
Perisic
Ljubica
L
Kaukinen
Anne
A
Szigyarto
Cristina Al-Khalili
CA
Uhlén
Mathias
M
Jalanko
Hannu
H
Betsholtz
Christer
C
Tryggvason
Karl
K
D000818:Animals; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism; D050199:Podocytes / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism*
D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; C470993:Ehd3 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; C521225:Ripor1 protein, mouse; D014157:Transcription Factors; C104328:dendrin; C521226:plekhh2 protein, mouse; C521227:sh2d4a protein, mouse