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Dlxin-1, a novel protein that binds Dlx5 and regulates its transcriptional function
Y Masuda1, A Sasaki, H Shibuya
1Department of Geriatric Research, National Institute for Longevity Sciences, 36-3 Gengo, Morioka-cho, Obu, Aichi 474-8522, Japan.
Abstract:
Dlx5, a member of the Dlx family of homeodomain proteins, plays a critical role in bone development and fracture healing. To understand the molecular mechanism underlying the transcriptional regulation by Dlx5, we performed yeast two-hybrid screening and isolated a novel protein, Dlxin-1, that binds Dlx5 and regulates its transcriptional function. Dlxin-1 cDNA encodes a 775-amino acid protein that has a partial homology with necdin at the C terminus and 25 repeats of hexapeptides (WQXPXX) in the middle region. Dlxin-1 mRNA is expressed in various adult tissues, but not the spleen, and also in osteoblastic and chondrogenic cell lines. During embryogenesis, a strong signal for Dlxin-1 mRNA was found in cell layers surrounding cartilaginous elements in bone rudiment during digit formation. Dlxin-1 binds not only Dlx5 but also Dlx7 and Msx2 and forms homomultimers in vivo. Transfection and reporter gene assays indicate that Dlxin-1 activates the transcriptional function of Dlx5. Therefore, Dlxin-1 may act as a regulator of the function of Dlx family members in bone formation.
Insights
Researchers identified Dlxin-1, a novel protein that binds and enhances the function of Dlx5, a key regulator of bone development and fracture healing. This discovery sheds light on the molecular mechanisms of bone formation.
Area of Science:
- Molecular Biology
- Developmental Biology
- Biochemistry
Background:
- Distal-less homeobox 5 (Dlx5) is crucial for bone development and fracture healing.
- Understanding Dlx5's transcriptional regulation is key to elucidating bone formation mechanisms.
Purpose of the Study:
- To identify novel proteins interacting with Dlx5.
- To characterize the function of Dlxin-1 in transcriptional regulation.
Main Methods:
- Yeast two-hybrid screening to identify Dlx5-interacting proteins.
- cDNA sequencing to determine Dlxin-1 protein structure.
- mRNA expression analysis in adult tissues and cell lines.
- In vivo and in vitro functional assays including transfection and reporter gene assays.
Main Results:
- A novel Dlx5-interacting protein, Dlxin-1, was identified.
- Dlxin-1 encodes a 775-amino acid protein with specific structural features.
- Dlxin-1 mRNA is expressed in bone-related tissues and cell lines.
- Dlxin-1 binds Dlx5, Dlx7, and Msx2, and forms homomultimers.
- Dlxin-1 enhances the transcriptional activity of Dlx5.
Conclusions:
- Dlxin-1 is a novel regulator of Dlx family member function.
- Dlxin-1 plays a significant role in bone formation processes.
- Further research into Dlxin-1 could reveal new therapeutic targets for bone disorders.