Kwang-Hyun Baek

DUB-1A, a Novel Deubiquitinating Enzyme Subfamily Member, Is Polyubiquitinated and Cytokine-inducible in B-lymphocytes

Recently, we isolated the Dub-2A gene, which encodes a novel murine deubiquitinating enzyme subfamily member, from a bacterial artificial chromosome library clone by PCR amplification with degenerate PCR primers for the Dub-2 cDNA (Baek, K.-H., Mondoux, M. A., Jaster, R., Fire-Levin E., and DAndrea, A. D. (2001) Blood 98, 636–642). In this study, we analyzed two more clones from the library to isolate genes encoding other deubiquitinating enzymes. Dub-1A, which encodes the shortest member of the DUB subfamily of deubiquitinating enzymes so far, has been identified in both clones and characterized. Sequence analysis showed that Dub-1A encodes a 468-amino acid protein that has a molecular mass of ∼51 kDa and that contains a putative catalytic domain (Cys, His, and Asp) conserved among DUB proteins. The amino acid sequence of DUB-1A is 84.5, 84.7, and 85.3% identical to those of DUB-1, DUB-2, and DUB-2A, respectively. Reverse transcription-PCR revealed that Dub-1A is expressed not only in B-lymphocytes in response to interleukin-3 stimulation, but also in T-lymphocytes, brain, heart, liver, lung, kidney, ovary, and spleen. This suggests that Dub-1A may play essential roles in each of these organs. In vivo and in vitro deubiquitinating enzyme assays showed that DUB-1A has functional deubiquitinating activity and that the 5′-flanking sequence of Dub-1A has a functional enhancer domain as shown in Dub-1 and Dub-2A. Interestingly, immunoblot analysis revealed that DUB-1A is polyubiquitinated, indicating that it is degraded through proteasome-mediated degradation. In the absence of JAK2, Dub-1A was expressed at a lower level. This suggests that DUB-1A functions downstream of JAK2 kinase in the interleukin-3 signaling pathway.

Comparison of gene expression at the fetomaternal interface between normal and recurrent pregnancy loss patients

Normal pregnancy requires a series of immunological, metabolic, vascular and endocrine regulating processes. However, the specific genes and proteins involved in these processes are not well defined. Aberration of these processes may lead to problems in pregnancy. One of these problems may be recurrent pregnancy loss (RPL). Little information is available on the level of expression of genes that may play a role in normal pregnancy. Therefore, this study determined whether different levels of gene expression at the feto-maternal interface could be associated with factors for RPL. The expression patterns of genes isolated from subtractive hybridization analysis performed with chorionic villi from normal and abnormal pregnancies were investigated. Eight genes classified into groups, including immunosuppression-related, embryo attachment-related and angiogenesis-related, were isolated.

Murine Asb-17 expression during mouse testis development and spermatogenesis

In this study we isolated a murine mAsb-17 from mouse testis by RT-PCR using primers designed based on the sequences from the GenBank database. The sequence analysis showed that mAsb-17 encodes a 295 amino acid polypeptide with a molecular weight of approximately 34 kDa containing two ankyrin repeats and one SOCS box. The amino acid sequence of mASB-17 showed 87.5%, 98.3% and 92.9% identity with that of human, rat and dog, respectively. Interestingly, northern blot analysis showed that mAsb-17 was expressed only in the testis. The expression analysis by RT-PCR for mAsb-17 in mouse indicates that mAsb-17 is expressed from the fourth week after birth to adult, with the highest expression in round spermatids. Both northern blot and RT-PCR analyses suggest that mASB-17 may play essential roles in testis development and spermatogenesis.

Molecular cloning and complete cDNA sequence of UBH1 in mouse testis.

We have identified a full-length mouse UBH1 cDNA, encoding a putative deubiquitinating enzyme, from the testis by RT-PCR using primers prepared from sequences conserved amongst deubiquitinating enzymes. Sequence analysis predicts that the UBH1 cDNA encodes a 355 amino acid polypeptide with the molecular weight of approximately 39 kDa containing the highly conserved Cys, Asp, and His domains characteristic of the ubiquitin-specific processing proteases. Biochemical assay revealed that the mouse UBH1 has deubiquitinating enzyme activity and sequence analysis showed 98.3% amino acid identity with human UBH1.