Anti-UBE2D2 monoclonal antibody, clone FQS22142(C)

There are currently no approved effective therapies for Alzheimer's disease (AD). AD is a classic, multifactorial, complex syndrome. Thus, a polypharmacological or multitargeted approach to AD might provide better therapeutic benefits than monotherapies. However, it remains elusive which biological processes and biomolecules involved in the pathophysiologic processes of AD would constitute good targets for multitargeted therapy. This study proposes that a co-module, consisting of biological processes, cellular pathways and nodes, in a molecular subnetwork perturbed by different therapeutic drugs may be the optimal therapeutic target for an AD multitarget-based intervention. Based on this hypothesis, genes regulated in the hippocampus and cortex of senescence-accelerated mouse prone-8 (SAMP8) mice by traditional Chinese medicine (TCM) prescriptions with different constituents and the same beneficial effects on AD, including the decoctions Liu-Wei-Di-Huang (LW), Ba-Wei-Di-Huang (BW), Danggui-Shaoyao-San (DSS), Huang-Lian-Jie-Du (HL) and Tiao-Xin-Fang (TXF), were investigated via cDNA microarray, and the perturbed subnetworks were constructed and interpreted. After comparing 15 perturbed subnetworks based on genes affected by LW, BW, HL, DSS and TXF, the results showed that the most important common nodes perturbed by these interventions in the brains of SAMP8 mice were RPS6KA1 and FHIT, and that other important common nodes included UBE2D2, STUB1 and AMFR. These five drugs simultaneously and significantly disturbed the regulation of apoptosis and protein ubiquitination among biological processes. These nodes and processes were key components of the co-module regulated by therapeutic drugs in a molecular subnetwork of AD. These results suggest that targeting candidate regulator of apoptosis and protein ubiquitination might be effective for AD treatment, and that RPS6KA1, FHIT, UBE2D2, STUB1 and AMFR might be optimal combinational targets of an AD multitarget-based therapy.

The Ubiquitin Proteasome System (UPS) is mainly responsible for the increased protein breakdown observed in muscle wasting. The E3 ligase MuRF1 is so far the only enzyme known to direct the main contractile proteins for degradation (i.e. troponin I, myosin heavy chains and actin). However, MuRF1 does not possess any catalytic activity and thus depends on the presence of a dedicated E2 for catalyzing the covalent binding of polyubiquitin (polyUb) chains on the substrates. The E2 enzymes belonging to the UBE2D family are commonly used for in vitro ubiquitination assays but no experimental data suggesting their physiological role as bona fide MuRF1-interacting E2 enzymes are available. In this work, we first found that the mRNA levels of critical E3 enzymes implicated in the atrophying program (MuRF1, MAFbx, Nedd4 and to a lesser extent Mdm2) are tightly and rapidly controlled during the atrophy (up regulation) and recovery (down regulation) phases in the soleus muscle from hindlimb suspended rats. By contrast, E3 ligases (Ozz, ASB2 beta and E4b) implicated in other processes (muscle development or regeneration) poorly responded to atrophy and recovery. UBE2B, an E2 enzyme systematically up regulated in various catabolic situations, was controlled at the mRNA levels like the E3s implicated in the atrophying process. By contrast, UBE2D2 was progressively repressed during atrophy and recovery, which makes it a poor candidate for a role during muscle atrophy. In addition, UBE2D2 did not exhibit any affinity with MuRF1 using either yeast two-hybrid or Surface Plasmon Resonance (SPR) approaches. Finally, UBE2D2 was unable to promote the degradation of the MuRF1 substrate a-actin in HEK293T cells, suggesting that no functional interaction exists between these enzymes within a cellular context. Altogether, our data strongly suggest that UBE2D2 is not the cognate ubiquitinating enzyme for MuRF1 and that peculiar properties of UBE2D enzymes may have biased in vitro ubiquitination assays. (C) 2016 Elsevier Ltd. All rights reserved.