p53 tumor suppressor protein is stabilized by the herpes-virus-associated ubiquitin-specific protease (HAUSP), a deubiquitinating enzyme. We previously isolated a mouse orthologue of HAUSP, mHAUSP, encoding 1103 amino acids with a molecular weight of approximately 135 kDa containing highly conserved Cys, Asp (I), His, and Asn/Asp (II) domains. In this study, we investigated the temporal and spatial expression of mHAUSP during the early mouse embryonic development. Northern blot analysis revealed that the expression of mHAUSP was detected throughout the process of embryonic development with the maximal expression between E10.5 and E13.5. In situ hybridization study showed the global expression of mHAUSP in various organs of embryos, including mesencephalon, spinal cord, lung and genital eminence. In addition, we carried out biochemical analysis for 6 conserved amino acids (Cys224, Gln231, Asp296, His457, His465, and Asp482) in Cys box, QQD box, and His box in order to investigate their structural and functional roles of these amino acid residues. The conserved Gln231 was not essential for the catalytic activity of mHAUSP. However, other conserved amino acids were required for deubiquitinating enzyme activity of mHAUSP. Moreover, we observed that the overexpression of mHAUSP induces cell death in HeLa cells.

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