Background: HIV-1 integration results in genomic DNA gaps that are repaired by cellular DNA repair pathways. This step of the lentiviral life cycle remains poorly understood despite its crucial importance for successful replication. We and others reported that Ku70 protein of the non-homologous end joining pathway (NHEJ) directly binds HIV-1 integrase (IN). Here, we studied the importance of this interaction for post-integrational gap repair and the recruitment of NHEJ factors in this process.Results: We engineered HIV-based pseudovirus with mutant IN defective in Ku70 binding and generated heterozygous Ku70, Ku80 and DNA-PKcs human knockout (KO) cells using CRISPR/Cas9. KO of either of these proteins or inhibition of DNA-PKcs catalytic activity substantially decreased the infectivity of HIV-1 with native IN but not with the mutant one. We used a recently developed qPCR assay for the measurement of gap repair efficiency to show that HIV-1 with mutant IN was defective in DNA post-integrational repair, whereas the wild type virus displayed such a defect only when NHEJ system was disrupted in any way. This effect was present in CRISPR/Cas9 modified 293T cells, in Jurkat and CEM lymphoid lines and in primary human PBMCs.Conclusions: Our data provide evidence that IN recruits DNA-PK to the site of HIV-1 post-integrational repair due to Ku70 binding—a novel finding that explains the involvement of DNA-PK despite the absence of free double stranded DNA breaks. In addition, our data clearly indicate the importance of interactions between HIV-1 IN and Ku70 in HIV-1 replication at the post-integrational repair step.

A t(9;22) chromosomal translocation which forms the chimeric tyrosine kinase breakpoint cluster region (BCR)‑Abelson murine leukemia viral oncogene homolog 1 (ABL) is a key mechanism underlying the pathogenesis of chronic myelogenous leukemia (CML). Pharmacological inhibition of BCR‑ABL with imatinib (Gleevec) has been reported as an effective targeted therapy; however, mutations (including the kinase domain of ABL) suppress the efficacy of inhibitors. PF‑114, a derivative of the third generation BCR‑ABL inhibitor ponatinib, demonstrated a high inhibitory activity against wild-type and mutant BCR‑ABL forms, such as the clinically important T315I. Furthermore, PF‑114 exhibited preferential kinase selectivity, safety, notable pharmacokinetic properties and therapeutic efficacy in a murine model. Investigation into the mechanisms of CML cell death revealed an exceptional potency of PF‑114 (at low nanomolar concentrations) for the CML‑derived K562 cell line, whereas leukemia cell lines that lack the chimeric tyrosine kinase were markedly more refractory. The molecular ordering of events mechanistically associated with K562 cell death included the dephosphorylation of CrkL adaptor protein followed by inhibition of ERK1/2 and Akt, G1 arrest, a decrease of phosphorylated Bcl‑2‑associated death promoter, Bcl‑2‑like protein 11, BH3 interacting‑domain death agonist, Bcl‑extra large and Bcl‑2 family apoptosis regulator, and reduced mitochondrial transmembrane potential. Increased Annexin V reactivity, activation of caspases and poly(ADP‑ribose)polymerase cleavage were proposed to lead to internucleosomal DNA fragmentation. Thus, PF‑114 may be a potent inducer of apoptosis in CML cells. Nevertheless, activation of STAT3 phosphorylation in response to PF‑114 may permit cell rescue; thus, a combination of BCR‑ABL and STAT3 inhibitors should be considered for improved therapeutic outcome. Collectively, the targeted killing of BCR‑ABL‑positive cells, along with other beneficial properties, such as in vivo characteristics, suggests PF‑114 as a potential candidate for analysis in clinical trials with CML patients.

Peripheral T lymphocytes can be subdivided into naive and antigen-experienced T cells. The latter, in turn, are represented by effector and central memory cells that are identified by different...

Complications after vaccination, lack of vaccines against certain infections, and the emergence of antibiotic-resistant microorganisms point to the need for alternative ways of protection and treatment of infectious diseases. Here, we proposed a therapeutic approach to control salmonellosis based on adoptive cell therapy. We showed that the T cell receptor (TCR) repertoire of salmonella-specific memory cells contains 20% of TCR variants with the dominant-active α-chain. Transduction of intact T lymphocytes with the dominant salmonella-specific TCRα led to their enhanced in vitro proliferation in response to salmonella. Adoptive transfer of transduced T cells resulted in a significant decrease in bacterial loads in mice infected with salmonella before or after the adoptive transfer. We demonstrated that adoptive immunotherapy based on T cells, transduced with dominant-specific TCRα could be successfully applied for treatment and prevention of infectious diseases and represent a useful addition to vaccination and existing therapeutic strategies.