Glial cell line derived neurotrophic factor is expressed by epithelia of human renal dysplasia.
OBJECTIVE
Differentiation of the metanephros is abnormal in cases of renal dysplasia, resulting in abnormal kidney organization. In vitro and in vivo studies indicate that glial cell line derived neurotrophic factor (GDNF) is a major regulator of kidney development and ureteral arborization. Therefore, we investigated the pattern of GDNF gene expression in human dysplastic kidneys.


METHODS
Specimens of whole tissues of human normal and dysplastic kidneys associated with obstructive uropathy were analyzed for GDNF mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR). Immunohistochemistry with GDNF antibody and laser capture microdissection plus RT-PCR were done to identify cells producing GDNF. Apoptosis, BCL-2 and Ki67 were also studied.


RESULTS
There were few if any GDNF transcripts in normal kidneys, whereas GDNF was over expressed in renal dysplasia specimens. Strong GDNF expression was found in the dysplastic tubules of dysplastic kidneys, whereas peritubular mesenchyma expressed no GDNF protein. Laser capture microdissection/RT-PCR detected GDNF mRNA in epithelial cells isolated from dysplastic tubules but not in cells from the surrounding mesenchyma, which was confirmed by sequence analysis. GDNF expression by epithelial cells was associated with high proliferation, BCL-2 expression and rare apoptosis.


CONCLUSIONS
GDNF gene expression is restricted to the tubular epithelium of dysplastic human kidneys. Our results strongly suggest that GDNF not only influences kidney morphogenesis, but is also implicated in abnormal kidney development.
El-Ghoneimi
Alaa
A
Department of Pediatric Surgery, Hôpital Robert Debré, Paris, France.
Berrebi
Dominique
D
Levacher
Beatrice
B
Nepote
Virginie
V
Infante
MurielL
M
Paris
Regine
R
Simonneau
Michel
M
Aigrain
Yves
Y
Peuchmaur
Michel
M
D017209:Apoptosis; D002648:Child; D002675:Child, Preschool; D004848:Epithelium / Q000378:metabolism; D015870:Gene Expression; D051100:Glial Cell Line-Derived Neurotrophic Factor; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007223:Infant; D007231:Infant, Newborn; D019394:Ki-67 Antigen / Q000032:analysis; D007668:Kidney / Q000002:abnormalities* / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism; D018613:Microscopy, Confocal; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
C495039:GDNF protein, human; D051100:Glial Cell Line-Derived Neurotrophic Factor; D019394:Ki-67 Antigen; D009414:Nerve Growth Factors; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger