Expression of novel podocyte-associated proteins sult1b1 and ankrd25.
OBJECTIVE
Podocytes have a unique function in the renal ultrafiltration that is achieved by expressing proteins that are highly specific to podocytes. In this study, we identified two novel podocyte-associated proteins.


METHODS
The expression of sult1b1 and ankrd25 in mouse tissues was studied by RT-PCR. The protein expression was studied by generating polyclonal antibodies that were used in Western blotting and immunohistochemistry.


RESULTS
By RT-PCR we detected sult1b1 expression only in glomerular, liver and brain tissues. By immunohistochemistry, sult1b1 was detected in the kidney exclusively in the Golgi apparatus of the podocyte. No expression outside the glomerulus was observed in the kidney. The ankrd25 transcript was detected in most mouse tissues analyzed by RT-PCR. In the kidney, however, immunohistochemistry showed that this protein was expressed only by podocyte, mesangial, and smooth muscle cells. In podocytes, ankrd25 was localized to foot processes.


CONCLUSIONS
Identification of these two novel glomerulus-associated proteins opens up possibilities to investigate their role in the renal filter physiology and diseases. We speculate that sult1b1 may be involved in the sulfonylation of podocyte protein podocalyxin, whereas ankrd25 may contribute to controlling actin dynamics in podocyte foot processes.
Xu
Xiangjun
X
Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
Patrakka
Jaakko
J
Sistani
Laleh
L
Uhlen
Mathias
M
Jalanko
Hannu
H
Betsholtz
Christer
C
Tryggvason
Karl
K
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000818:Animals; D017089:Ankyrin Repeat; D001483:Base Sequence; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D051379:Mice; D050199:Podocytes / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015238:Sulfotransferases / Q000235:genetics* / Q000378:metabolism*; D014018:Tissue Distribution; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D017931:DNA Primers; C467739:KANK1 protein, human; C538755:Kank1 protein, mouse; D025521:Tumor Suppressor Proteins; D015238:Sulfotransferases; C109377:iodothyronine sulfotransferase