LLC-PK1 cell growth is repressed by WT1 inhibition of G-protein alpha i-2 protooncogene transcription.
The temporal expression of the early growth response gene (EGR-1) is one molecular mechanism for both maximal activation of the G alpha i-2 gene and accelerated growth in mitotically active predifferentiated LLC-PK1 renal cells. These events are dependent on an enhancer area in the 5'-flanking region of the G alpha i-2 gene that contains an EGR-1 motif (5'-CGCCCCCGC-3'). However, acquisition of the polarized phenotype in LLC-PK1 cells is accompanied by loss of EGR-1 expression and occupancy of the EGR-1 site by nuclear binding proteins other than EGR-1. We now demonstrate that one of these binding proteins is the Wilms' tumor suppressor (WT1). Furthermore, the temporal expression of WT1 in LLC-PK1 cells acquiring the polarized phenotype represses both G alpha i-2 gene activation and growth in these cells. These findings suggest the existence of differentiation-induced pathways in LLC-PK1 cells that alternatively abrogates EGR-1 and promotes WT1 gene expression, thereby modulating a target protooncogene G alpha i-2 that is participatory for growth and differentiation in renal cells. These studies emphasize the usefulness of the LLC-PK1 renal cell as a model to elucidate normal programs of genetic differentiation in which WT1 participates.
Kinane
T B
TB
Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania 19104, USA.
Finder
J D
JD
Kawashima
A
A
Brown
D
D
Abbate
M
M
Fredericks
W J
WJ
Sukhatme
V P
VP
Rauscher
F J
FJ
Ercolani
L
L
D000818:Animals; D001483:Base Sequence; D002455:Cell Division; D003470:Culture Media; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015870:Gene Expression; D016162:Genes, Wilms Tumor; D006801:Humans; D017874:Immediate-Early Proteins; D015151:Immunoblotting; D018374:LLC-PK1 Cells; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011519:Proto-Oncogenes; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D013552:Swine; D014157:Transcription Factors / Q000096:biosynthesis* / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D025721:WT1 Proteins; D016335:Zinc Fingers
D003470:Culture Media; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D025721:WT1 Proteins; D019204:GTP-Binding Proteins