A novel member of murine Polycomb-group proteins, Sex comb on midleg homolog protein, is highly conserved, and interacts with RAE28/mph1 in vitro

Daihachiro Tomotsune, Yoshihiro Takihara, Joel Berger, David Duhl, Joo Sunghae, Michael Kyba, Manabu Shirai, Hideaki Ohta, Yoichi Matsuda, Barry M. Honda, Jeffrey Simon, Kazunori Shimada, Hugh W. Brock, Filippo Randazzo

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


The Polycomb group of (PcG) genes were originally described in Drosophila, but many PcG genes have mammalian homologs. Genetic studies in flies and mice show that mutations in PcG genes cause posterior transformations caused by failure to maintain repression of homeotic loci, suggesting that PcG proteins have conserved functions. The Drosophila gene Sex comb on midleg (Scm) encodes an unusual PcG protein that shares motifs with the PcG protein polyhomeotic, and with a Drosophila tumor suppressor, lethal(3)malignant brain tumor (l(3)mbt). Expressed sequence tag (EST) databases were searched to recover putative mammalian Scm homologs, which were used to screen murine cDNA libraries. The recovered cDNA encodes two mbt repeats and the SPM domain that characterize Scm, but lacks the cysteine clusters and the serine/threonine-rich region found at the amino terminus of Scm. Accordingly, we have named the gene Sex comb on midleg homolog I (Scmh1). Like their Drosophila counterparts, Scmh1 and the mammalian polyhomeotic homolog RAE28/mph1 interact in vitro via their SPM domains. We analyzed the expression of Scmh1 and rae28/mph1 using northern analysis of embryos and adult tissues, and in situ hybridization to embryos. The expression of Scmh1 and rae28/mph1 is well correlated in most tissues of embryos. However, in adults, Scmh1 expression was detected in most tissues, whereas mph1/rae28 expression was restricted to the gonads. Scmh1 is strongly induced by retinoic acid in F9 and P19 embryonal carcinoma cells. Scmh1 maps to 4D1-D2.1 in mice. These data suggest that Scmh1 will have an important role in regulation of homeotic genes in embryogenesis and that the interaction with RAE28/mph1 is important in vivo.

Original languageEnglish (US)
Pages (from-to)229-239
Number of pages11
Issue number4
StatePublished - 1999

Bibliographical note

Funding Information:
Acknowledgments We thank the Jackson Laboratories, Lucy Rowe and Lucy Rowe and Mary Barter of Jackson Labs and the Jackson Labs backcross DNA mapping panel resource for the materials and assistance. We thank Jeffery Tucker, Roger Wang and Mojgan Amir-Ebrahimi for DNA sequencing. This work was supported by a Grant-in-Aid for International Scientific Research, and a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan to K.S., Y.T, and D.T, and by grants from the Natural Sciences and Engineering Research Council to B.H and H.W.B, and from the Medical Research Council to H.W.B. We are grateful for the generous use of Genome Information Research Center in Osaka University and Genome Systems in Chiron Corporation. We thank Dr. Z. Zho, M. Miyazaki and N. Sugimoto for technical support.


  • Chromatin
  • Homeotic
  • L(3)mbt
  • Polycomb group
  • Polyhomeotic
  • RAE28/mph1
  • Scmh1
  • Sex comb on midleg


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