Human USP15 blocking peptide

Spindle cell tumors are clinically heterogeneous but morphologically similar neoplasms that can occur anywhere, mostly in adult patients. They are treated primarily with surgery to which is often added adjuvant or neoadjuvant radiation. Sub-classification of spindle cell sarcomas requires integration of histology, clinicopathological parameters, immunohistochemistry, cytogenetics (including fluorescence in situ hybridization) and/or molecular genetics. Some of the tumor subtypes are characterized by the presence of distinct chromosomal translocations and fusion genes. When no signs of differentiation are seen, the diagnosis by exclusion becomes undifferentiated spindle cell sarcoma. Cytogenetic, RNA sequencing and RT-PCR analyses were performed on a case of spindle cell sarcoma. The karyotype of the primary tumor was 46,X,del(X)(p?11p?22), der(12)(12pter -> 12q?22::12q?15 -> q?22::16p11 -> 16pter),-16,+r(12). MDM2 was found amplified in both the primary tumor and a metastasis. RNA-Seq of the primary tumor identified four fusion genes, PTGES3-PTPRB, HMGA2-DYRK2, TMBIM4-MSRB3 and USP15-CNTN1, in which all the partner genes map to the q arm of chromosome 12. In material from the metastasis, RT-PCR detected the PTGES3-PTPRB, HMGA2-DYRK2 and TMBIM4-MSRB3 whereas no USP15-CNTN1 fusion transcript was found. Because MDM2 amplification and the fusion transcripts PTGES3-PTPRB, HMGA2-DYRK2 and TMBIM4-MSRB3 were found both in the primary tumor and in the metastasis, they are components of the same clone and may be involved both in initiation and progression of the tumor. Which of them is pathogenetically primary remains unknown.

The transcription factor retinoid acid-related orphan receptor gamma t (ROR gamma t) directs the differentiation of Th17 cells. Th17 cells mediate pathological immune responses responsible for autoimmune diseases, including psoriasis and multiple sclerosis. Previous studies focused on ROR gamma t target genes and their function in Th17 differentiation. In this study, we assessed posttranscriptional regulation of ROR gamma t and identified a functional ubiquitination site, K446. Mutation of K446 to arginine to prevent ubiquitination greatly enhanced recruitment of steroid receptor coactivator 1 (SRC1), a coactivator critical for ROR gamma t activity. Correspondingly, the K446 to arginine mutation potentiated Th17 differentiation. We also showed that ubiquitin-specific protease (USP) 15 interacted with ROR gamma t, removed ubiquitin from K446, and stimulated ROR gamma t activity by enhancing coactivator SRC1 recruitment. Knockdown of USP15 or expression of inactive USP15 impaired Th17 differentiation, suggesting a positive role for USP15-mediated deubiquitination of ROR gamma t in Th17 differentiation. Therefore, ubiquitination of K446 limits ROR gamma t-mediated Th17 differentiation by inhibiting the recruitment of coactivator SRC1. Our study will inform the development of treatments that target ROR gamma t ubiquitination pathways to limit Th17-mediated autoimmunity.