Oncogene database

440414

TRE17

TRE17 protein;-;-

-

17p11.2

protein-coding

Aneurysmal bone cyst (ABC) is a pediatric osseous tumor characterized by extensive destruction of the surrounding bone. The molecular mechanisms underlying its pathogenesis are completely unknown. Recent work showed that translocation of the TRE17/USP6 locus occurs in over 60% of ABC cases resulting in TRE17 overexpression. Immature osteoblasts are presumed to be the cell type harboring translocation of TRE17 in at least a subset of ABCs. However, the effects of TRE17 overexpression on transformation and osteoblast function are unknown. TRE17 encodes a ubiquitin-specific protease (USP) and a TBC (TRE2-Bub2-Cdc16) domain that promotes activation of the Arf6 GTPase. Here we report that TRE17 potently inhibits the maturation of MC3T3 pre-osteoblasts in a USP-dependent and Arf6-independent manner. Notably, we find that TRE17 function is mediated through an autocrine mechanism. Transcriptome analysis of TRE17-expressing cells reveals dysregulation of several pathways with established roles in osteoblast maturation. In particular, signaling through the bone morphogenetic protein (BMP) pathway, a key regulator of osteogenesis, is profoundly altered. TRE17 simultaneously inhibits the expression of BMP-4 while augmenting the BMP antagonist, Gremlin-1. Osteoblastic maturation is restored in TRE17-expressing cells by the addition of exogenous BMP-4, thus establishing a functional role for BMP-4 during TRE17-induced transformation. Because bone homeostasis involves a precise balance between the activities of osteoblasts and osteoclasts, our studies raise the possibility that attenuated osteoblast maturation caused by TRE17 overexpression may contribute to the bone loss/destruction observed in ABC.

The NF-kappaB transcription factor has a central role in diverse processes, including inflammation, proliferation and cell survival, and its activity is dysregulated in diseases such as autoimmunity and cancer. We recently identified the TRE17/ubiquitin-specific protease 6 (USP6) oncogene as the first de-ubiquitinating enzyme to activate NF-kappaB. TRE17/USP6 is translocated and overexpressed in aneurysmal bone cyst (ABC), a pediatric tumor characterized by extensive bone degradation and inflammatory recruitment. In the current study, we explore the mechanism by which TRE17 induces activation of NF-kappaB, and find that it activates the classical NF-kappaB pathway through an atypical mechanism that does not involve IkappaB degradation. TRE17 co-precipitates with IkappaB kinase (IKK), and IKK activity is augmented in stable cell lines overexpressing TRE17, in a USP-dependent manner. Optimal activation of NF-kappaB by TRE17 requires both catalytic subunits of IKK, distinguishing its mechanism from the classical and non-canonical pathways, which require either IKKbeta or IKKalpha, respectively. TRE17 stimulates phosphorylation of p65 at serine 536, a modification that has been associated with enhanced transcriptional activity and nuclear retention. Induction of S536 phosphorylation by TRE17 requires both IKKalpha and IKKbeta, as well as the IKKgamma/NEMO regulatory subunit of IKK. We further demonstrate that TRE17(long) is highly tumorigenic when overexpressed in NIH3T3 fibroblasts, and that inhibition of NF-kappaB significantly attenuates tumor formation. In summary, these studies uncover an unexpected signaling mechanism for activation of classical NF-kappaB by TRE17. They further reveal a critical role for NF-kappaB in TRE17-mediated tumorigenesis, and suggest that NF-kappaB inhibitors may function as effective therapeutic agents in the treatment of ABC.

BACKGROUND INFORMATION: cancer cells are characterized by their intrinsic ability to rapidly divide and migrate and to invade other tissues. How these processes are regulated at a molecular level is largely unknown. RESULTS: Here, we identify the oncogenic TBC (Tre-2/Bub2/Cdc16) domain protein USP6 (also termed TRE17) as a regulator of both cell migration and division. We show that manipulating USP6 expression levels alters the ability of cells to migrate and to divide. Furthermore, we observe that cell proliferation and progression through cytokinesis depend on USP6 expression via a pathway that involves the small GTPase Arf6 and its GTPase-activating protein ACAP1. CONCLUSIONS: Our data suggest a model whereby the oncogenic potential of USP6 is linked to its ability to integrate cell migration and cytokinesis by regulating Arf6/ACAP1.

De-ubiquitinating enzymes (DUBs) play critical roles in diverse cellular processes, including intracellular trafficking, protein turnover, inflammatory signaling, and cell transformation. The first DUB to be identified as an oncogene was TRE17/Ubiquitin-specific protease 6 (USP6)/Tre-2. In addition to encoding a USP, TRE17 also contains a TBC (Tre-2/Bub2/Cdc16) domain implicated in GTPase regulation and trafficking. Though first described almost two decades ago, remarkably little has been elucidated regarding TRE17 s molecular and cellular functions. However, recent work has implicated TRE17 as a key etiological factor in aneurysmal bone cyst (ABC), a locally recurrent pediatric bone tumor, and identified potential pathways through which it acts. In this review, we discuss the most up-to-date findings on the molecular functions of TRE17, the role of its USP and TBC domains, and potential models for how it contributes to transformation and ABC pathogenesis.

The tre oncogenic locus was identified in transformants receiving human DNA from Ewing s sarcoma cells EW1. Genetic elements of tre originate from chromosomes 5, 18, and 17. The TRE17 oncogene is consistently transcribed in various human cancer cells and proves oncogenic (onc) in expression vector-based assays. Here, the nucleotide sequence of TRE17 with defined noncoding and two coding exons (4,426 nucleotides) was compared with sequences cloned from placental DNA library or generated by polymerase chain reaction (PCR) from EW1 and independent healthy individuals. Cloned sequences displayed restriction site polymorphism, with different patterns for EW1 and normal tissues. Sequence analysis revealed that they originate from a family of homologous sequences alpha, beta, and gamma. TRE17 alpha and less frequent TRE17 beta (similarity score approximately equal to 88%) were found in both normal and EW1 cells. oncTRE17, classified as TRE17 beta, differed from the wild-type TRE17 beta, besides a few intronic changes, by a single-base frameshift insertion in one of the coding exons. TRE17 gamma, so far identified in EW1 but not in normal somatic cells, diverged from oncTRE17 by 6% nucleotide substitutions and by stop codons in each reading frame. The results are consistent with the possibility that TRE17 sequences other than oncTRE17 are translated if alternatively spliced. expression of TRE17 in normal somatic cells was, however, not yet reported.

The G0S19-1/MIP1alpha and G0S19-2/MIP1alpha genes locate to human chromosomes 17q and encode similar copies of the beta-chemokine G0S19/MIP1alpha. The G0S19-3 gene, present in 1 in 4 humans, is a 5 truncated version of G0S19-2; a CpG island-containing upstream sequence (CpG-US), rich in potential transcriptional activation motifs, replaces much of the first intron and the first exon. Sequences hybridizing with the CpG-US sequence, normally exist in ALL human genomes. Thus, it appears that there has been recombination between a duplicated G0S19 gene and a duplicated CpG-US-like sequence. We have isolated sequences hybridizing with the CpG-US sequence from a human genomic library in bacteriophage lambda. Restriction mapping and sequencing shows a CpG-US-like sequence approximately 8 kb downstream of G0S19-2 (hence, named CpG-DS sequence). The sequence is contiguous with a TRE17 oncogene-associated sequence (GenBank locus HSTRE175). Members of the TRE17 family are known to locate to chromosome 17q (Onno et al., 1993b), and have sequence characteristics suggestive of positive Darwinian selection. Linkage with a TRE17 oncogene may have arisen by recombination and imply no functional relationship. However, it is possible that the CpG-DS may normally regulate TRE17 expression. PCR and sequencing studies indicate the close proximity of other chemokine-related sequences in the 17q11.2 region.