Nephrin is expressed in the pancreatic beta cells.
OBJECTIVE
The NPHS1 gene product, nephrin, is a crucial component of the glomerular filtration barrier preventing proteinuria and previously assumed to be kidney-specific. The aim of this study was to describe the expression of nephrin mRNA and protein in human pancreas as well as identify the nephrin-expressing cell types.


METHODS
RNA dot blot, reverse transcriptase-polymerase chain reaction, sequencing, immunoblotting and dual immunofluorescence were used for the characterisation of nephrin in the pancreas.


RESULTS
Except for the kidney, the pancreas was found to be the only tissue expressing nephrin as screened with a human tissue RNA dot blot. The expression was verified with reverse transcriptase-polymerase chain reaction and by sequencing nephrin from a human pancreatic complementary DNA library. Nephrin antibody in immunoblot detected a 165,000 M(r) protein in the pancreas. Dual immunofluorescence showed that nephrin was specifically localised in the beta cells of the islets of Langerhans. There was no overlap with glucagon, somatostatin, or the ductal cell marker cytokeratin 19.


CONCLUSIONS
These data show that nephrin is a novel molecule of pancreatic beta cells.
Palmén
T
T
Haartman Institute, Division of Bacteriology and Immunology, University of Helsinki, and Helsinki University Central Hospital Helsinki, Finland.
Ahola
H
H
Palgi
J
J
Aaltonen
P
P
Luimula
P
P
Wang
S
S
Jaakkola
I
I
Knip
M
M
Otonkoski
T
T
Holthöfer
H
H
D002102:Cadaver; D016650:Fluorescein-5-isothiocyanate; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D015870:Gene Expression; D005934:Glucagon / Q000032:analysis; D006801:Humans; D015151:Immunoblotting; D007515:Islets of Langerhans / Q000378:metabolism*; D007633:Keratins / Q000032:analysis; D007668:Kidney / Q000737:chemistry / Q000196:embryology; D007672:Kidney Cortex / Q000737:chemistry; D008565:Membrane Proteins; D008970:Molecular Weight; D010179:Pancreas / Q000737:chemistry; D011506:Proteins / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013004:Somatostatin / Q000032:analysis
D005456:Fluorescent Dyes; D008565:Membrane Proteins; D011506:Proteins; D012333:RNA, Messenger; C113267:nephrin; D013004:Somatostatin; D007633:Keratins; D005934:Glucagon; D016650:Fluorescein-5-isothiocyanate