Co-expressed recombinant human Translin-Trax complex binds DNA

AbstractTrax, expressed alone aggregates into insoluble complexes, whereas upon co-expression with Translin becomes readily soluble and forms a stable heteromeric complex (∼430kDa) containing both proteins at nearly equimolar ratio. Based on the subunit molecular weights, estimated by MALDI-TOF-MS, the purified complex appears to comprise of either an octameric Translin plus a hexameric Trax (calculated MW 420kDa) or a heptamer each of Trax and Translin (calculated MW 425kDa) or a hexameric Translin plus an octameric Trax (calculated MW 431kDa). The complex binds single-stranded/double-stranded DNA. ssDNA gel-shifted complex shows both proteins at nearly equimolar ratio, suggesting that Translin “chaperones” Trax and forms heteromeric complex that is DNA binding competent

GTP-induced conformational changes in translin: a comparison between human and Drosophila proteins

Human translin is a conserved protein, unique in its ability to bind both RNA and DNA. Interestingly, GTP binding has been implicated as a regulator of RNA/DNA binding function of mouse translin (TB-RBP). We cloned and overexpressed the translin orthologue from Drosophila melanogaster and compared its DNA/RNA binding properties in relation to GTP effects with that of human protein. Human translin exhibits a stable octameric state and binds ssDNA/RNA/dsDNA targets, all of which get attenuated when GTP is added. Conversely, Drosophila translin exhibits a stable dimeric state that assembles into a suboctameric (tetramer/hexamer) form and fails to bind ssDNA and RNA targets. Interestingly enough, CD spectral analyses, partial protease digestion profile revealed GTP-specific conformational changes in human translin, whereas the same were largely missing in Drosophila protein. Isothermal calorimetry delineated specific heat changes associated with GTP binding in human translin, which invoked subunit “loosening” in its octamers; the same effect was absent in Drosophila protein. We propose that GTP acts as a specific molecular “switch” that modulates the nucleic acid binding function selectively in human translin, perhaps by affecting its octameric configuration

Efficacy of checkpoint inhibition after CAR-T failure in aggressive B-cell lymphomas: Outcomes from 15 U.S. institutions

Checkpoint inhibitor (CPI) therapy with anti-PD-1 antibodies has been associated with mixed outcomes in small cohorts of aggressive B-cell lymphoma patients following CAR T-cell therapy failure. To more definitively define CPI therapy efficacy in this population, we retrospectively evaluated clinical outcomes in a large cohort of 96 patients with aggressive B-cell lymphomas receiving CPI therapy after CAR-T failure across 15 U.S. academic centers. Most patients (53%) had DLBCL, were treated with axicabtagene ciloleucel (53%), relapsed early (≤180 days) after CAR-T (83%), and received pembrolizumab (49%) or nivolumab (43%). CPI therapy was associated with an overall response rate of 19% and a complete response rate of 10%. Median duration of response was 221 days. Median progression-free survival (PFS) and overall survival (OS) were 54 and 159 days, respectively. Outcomes to CPI therapy were significantly improved in patients with primary mediastinal B-cell lymphoma. PFS (128 versus 51 days) and OS (387 versus 131 days) were significantly longer in patients with late (>180 days) versus early (≤180 days) relapse after CAR-T. Grade ≥3 adverse events occurred in 19% of CPI-treated patients. Most patients (83%) died, commonly due to progressive disease. Only 5% had durable responses to CPI therapy. In the largest cohort of aggressive B-cell lymphoma patients treated with CPI therapy after CAR-T relapse, our results reveal poor outcomes, particularly among those relapsing early after CAR-T. In conclusion, CPI therapy is not an effective salvage strategy for most patients after CAR-T, where alternative approaches are needed to improve post-CAR-T outcomes