Characterization of the human suppressor of fused, a negative regulator of the zinc-finger transcription factor Gli.
Drosophila Suppressor of fused (Su(fu)) encodes a novel 468-amino-acid cytoplasmic protein which, by genetic analysis, functions as a negative regulator of the Hedgehog segment polarity pathway. Here we describe the primary structure, tissue distribution, biochemical and functional analyses of a human Su(fu) (hSu(fu)). Two alternatively spliced isoforms of hSu(fu) were identified, predicting proteins of 433 and 484 amino acids, with a calculated molecular mass of 48 and 54 kDa, respectively. The two proteins differ only by the inclusion or exclusion of a 52-amino-acid extension at the carboxy terminus. Both isoforms were expressed in multiple embryonic and adult tissues, and exhibited a developmental profile consistent with a role in Hedgehog signaling. The hSu(fu) contains a high-scoring PEST-domain, and exhibits an overall 37% sequence identity (63% similarity) with the Drosophila protein and 97% sequence identity with the mouse Su(fu). The hSu(fu) locus mapped to chromosome 10q24-q25, a region which is deleted in glioblastomas, prostate cancer, malignant melanoma and endometrial cancer. HSu(fu) was found to repress activity of the zinc-finger transcription factor Gli, which mediates Hedgehog signaling in vertebrates, and to physically interact with Gli, Gli2 and Gli3 as well as with Slimb, an F-box containing protein which, in the fly, suppresses the Hedgehog response, in part by stimulating the degradation of the fly Gli homologue. Coexpression of Slimb with Su(fu) potentiated the Su(fu)-mediated repression of Gli. Taken together, our data provide biochemical and functional evidence for the hypothesis that Su(fu) is a key negative regulator in the vertebrate Hedgehog signaling pathway. The data further suggest that Su(fu) can act by binding to Gli and inhibiting Gli-mediated transactivation as well as by serving as an adaptor protein, which links Gli to the Slimb-dependent proteasomal degradation pathway.
Stone
D M
DM
Departments of Neuroscience, Genentech, Inc. 1 DNA Way, South San Francisco, CA 94080, USA.
Murone
M
M
Luoh
S
S
Ye
W
W
Armanini
M P
MP
Gurney
A
A
Phillips
H
H
Brush
J
J
Goddard
A
A
de Sauvage
F J
FJ
Rosenthal
A
A
D000328:Adult; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002874:Chromosome Mapping; D002879:Chromosomes, Human, Pair 10; D003001:Cloning, Molecular; D004330:Drosophila; D029721:Drosophila Proteins; D005260:Female; D005333:Fetus; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008156:Luciferases / Q000235:genetics; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism*; D000071676:Zinc Finger Protein GLI1; D016335:Zinc Fingers
D029721:Drosophila Proteins; D015513:Oncogene Proteins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C490764:SUFU protein, human; C097059:Su(fu) protein, Drosophila; C490763:Sufu protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1; D008156:Luciferases