Anti-UBE2I polyclonal antibody

Background: The transcription factor TWIST1 has been described to regulate the microRNA (miR)-199/214 cluster. Genetic disruption of TWIST1 resulted in a cachectic phenotype and early death of the knock-out mice. This might be connected to the activity of the ubiquitin-proteasome-system (UPS), as miR-199a has been suggested to regulate the ubiquitin E2 ligases Ube2i and Ube2g1. Methods: Cardiac tissue from explanted hearts of 42 patients with dilated cardiomyopathy and 20 healthy donor hearts were analysed for protein expression of TWIST1 and its inhibitors Id-1, MuRF-1 and MAFbx, the expression of miR-199a, -199b and -214, as well as the activity of the UPS by using specific fluorogenic substrates. Results: TWIST1 was repressed in patients with dilated cardiomyopathy by 43% (p=0.003), while Id1 expression was unchanged. This was paralleled by a reduced expression of miR-199a by 38 +/- 9% (p=0.053), miR-199b by 36 +/- 13% (p=0.019) and miR-214 by 41 +/- 11% (p=0.0158) compared to donor hearts. An increased peptidylglutamyl-peptide-hydrolysing activity (p<0.0001) was observed in the UPS, while the chymotrypsin-like and trypsin-like activities were unchanged. The protein levels of the rate limiting ubiquitin E3-ligases MuRF-1 and MAFbx were up-regulated (p=0.005 and p=0.0156, respectively). Mechanistically silencing of TWIST1 using siRNA in primary rat cardiomyocytes led to a down-regulation of the miR-199/214 cluster and to a subsequent up-regulation of Ube2i. Conclusion: The TWIST1/miR-199/214 axis is down-regulated in dilated cardiomyopathy, which is likely to play a role in the increased activity of the UPS. This may contribute to the loss of cardiac mass during dilatation of the heart. (c) 2013 Published by Elsevier Ireland Ltd.

Multiple myeloma (MM) is a plasma cell neoplasm that proceeds through a premalignant state of monoclonal gammopathy of unknown significance; however, the molecular events responsible for myelomagenesis remain uncharacterized. To identify cellular pathways deregulated in MM, we addressed that sumoylation is homologous to ubiquitination and results in the attachment of the ubiquitin-like protein Sumo onto target proteins. Sumoylation was markedly enhanced in MM patient lysates compared with normal plasma cells and expression profiling indicated a relative induction of sumoylation pathway genes. The Sumo-conjugating enzyme Ube2I, the Sumo-ligase PIAS1, and the Sumo-inducer ARF were elevated in MM patient samples and cell lines. Survival correlated with expression because 80% of patients with low UBE2I and PIAS1 were living 6 years after transplantation, whereas only 45% of patients with high expression survived 6 years. UBE2I encodes the sole Sumo-conjugating enzyme in mammalian cells and cells transfected with a dominant-negative sumoylation-deficient UBE2I mutant exhibited decreased survival after radiation exposure, impaired adhesion to bone marrow stroma cell and decreased bone marrow stroma cell-induced proliferation. UBE2I confers cells with multiple advantages to promote tumorigenesis and predicts decreased survival when combined with PIAS1. The sumoylation pathway is a novel therapeutic target with implications for existing proteasomal-based treatment strategies. (Blood. 2010; 115(14): 2827-2834)