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Expression of Runx2 transcription factor in non-skeletal tissues, sperm and brain

Authors

  • Jae-Hwan Jeong,

    1. Department of Biochemistry and Cell Biology, School of Medicine, Cell and Matrix Research Institute, Skeletal Diseases Genome Research Center, Kyungpook National University, Daegu, Republic of Korea
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  • Jung-Sook Jin,

    1. Department of Biochemistry and Cell Biology, School of Medicine, Cell and Matrix Research Institute, Skeletal Diseases Genome Research Center, Kyungpook National University, Daegu, Republic of Korea
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  • Hyun-Nam Kim,

    1. Department of Biochemistry and Cell Biology, School of Medicine, Cell and Matrix Research Institute, Skeletal Diseases Genome Research Center, Kyungpook National University, Daegu, Republic of Korea
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  • Sang-Min Kang,

    1. Department of Biochemistry and Cell Biology, School of Medicine, Cell and Matrix Research Institute, Skeletal Diseases Genome Research Center, Kyungpook National University, Daegu, Republic of Korea
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  • Julie C. Liu,

    1. Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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  • Christopher J. Lengner,

    1. Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts
    Current affiliation:
    1. White Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142.
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  • Florian Otto,

    1. Division of Hematology/Oncology, Medical Center, University of Freiburg, Freiburg, Germany
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  • Stefan Mundlos,

    1. Max Planck Institute for Molecular Genetics, Berlin, Germany
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  • Janet L. Stein,

    1. Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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  • Andre J. van Wijnen,

    1. Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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  • Jane B. Lian,

    1. Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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  • Gary S. Stein,

    1. Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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  • Je-Yong Choi

    Corresponding author
    1. Department of Biochemistry and Cell Biology, School of Medicine, Cell and Matrix Research Institute, Skeletal Diseases Genome Research Center, Kyungpook National University, Daegu, Republic of Korea
    • 101 Dong-In Dong, Jung-Gu, Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu 700-422, Republic of Korea.
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Abstract

Runx2 is a master transcription factor for chondrocyte and osteoblast differentiation and bone formation. However expression of Runx2 (by RT-PCR), has been reported in non-skeletal tissues such as breast, T cells and testis. To better define Runx2 activity in non-skeletal tissues, we examined transgenic (Tg) mice expressing LacZ gene under control of 3.0 kb (3 kb Tg) or 1.0 kb (1 kb Tg) of the Runx2 distal (P1) promoter, Runx2 LacZ knock-in (Runx2+/LacZ) and Runx2/P1 LacZ knock-in (Runx2/P1+/LacZ). In the Runx2 3 kb Tg mouse, β-galactosidase (β-gal) expression appeared in various non-skeletal tissues including testis, skin, adrenal gland and brain. β-gal expression from both 3 kb and 1 kb Tg, reflecting activity of the Runx2 promoter, was readily detectable in seminiferous tubules of the testis and the epididymis. At the single cell level, β-gal was detected in spermatids and mature sperms not in sertoli or Leydig cells. We also detected a positive signal from the Runx2+/LacZ and Runx2/P1+/LacZ mice. Indeed, Runx2 expression was observed in isolated mature sperms, which was confirmed by RT-PCR and Western blot analysis. Runx2, however, was not related to sex determination and sperm motility. Runx2 mediated β-gal activity is also found robustly in the hippocampus and frontal lobe of the brain in Runx2+/LacZ. Collectively, these results indicate that Runx2 is expressed in several non-skeletal tissues particularly sperms of testis and hippocampus of brain. It suggests that Runx2 may play an important role in male reproductive organ testis and brain. J. Cell. Physiol. 217: 511–517, 2008. © 2008 Wiley-Liss, Inc.

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