Cloning and characterization of rat BAT3 cDNA

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• HLA-B-associated transcript 3 (BAT3) is a gene within the human major histocompatibility complex.
• BAT3 encodes a large proline-rich protein with a currently unknown function.

Purpose of the Study:

• To investigate the function of BAT3.
• To identify proteins that interact with BAT3.
• To characterize the expression and localization of BAT3.

Main Methods:

• Yeast-based two-hybrid system to identify interacting proteins.
• Cloning of full-length rat BAT3 cDNA.
• Sequence analysis and deletion experiments.
• Green fluorescent protein (GFP) tagging for cellular localization studies.
• Northern hybridization for mRNA expression analysis.

Main Results:

• A fragment of BAT3 was found to interact with the candidate tumor suppressor DAN.
• Full-length rat BAT3 cDNA (3617 nucleotides) encodes a 1098-amino acid protein with 87.4% identity to human BAT3.
• The N-terminal region (amino acid residues 1-80) of DAN is essential for BAT3 interaction.
• GFP-tagged BAT3 localizes primarily to the cytoplasm of COS cells.
• BAT3 mRNA is expressed in all adult rat tissues, with highest levels in the testis.
• BAT3 mRNA expression is downregulated in v-mos- and v-Ha-ras-transformed 3Y1 cells compared to parental cells.

Conclusions:

• BAT3 interacts with the tumor suppressor DAN, suggesting a role in cellular regulation.
• BAT3 exhibits tissue-specific expression, predominantly in the testis.
• Downregulation of BAT3 in transformed cells suggests a potential role as a tumor suppressor or in maintaining cellular transformation status.