Intracellular Conformation of Amyotrophic Lateral Sclerosis-Causative TDP-43

Transactive response element DNA/RNA-binding protein 43 kDa (TDP-43) is the causative protein of amyotrophic lateral sclerosis (ALS); several ALS-associated mutants of TDP-43 have been identified. TDP-43 has several domains: an N-terminal domain, two RNA/DNA-recognition motifs, and a C-terminal intrinsically disordered region (IDR). Its structures have been partially determined, but the whole structure remains elusive. In this study, we investigate the possible end-to-end distance between the N- and C-termini of TDP-43, its alterations due to ALS-associated mutations in the IDR, and its apparent molecular shape in live cells using Forster resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS). Furthermore, the interaction between ALS-associated TDP-43 and heteronuclear ribonucleoprotein A1 (hnRNP A1) is slightly stronger than that of wild-type TDP-43. Our findings provide insights into the structure of wild-type and ALS-associated mutants of TDP-43 in a cell

Interaction of RNA with a C-terminal fragment of the amyotrophic lateral sclerosis-associated TDP43 reduces cytotoxicity

A hallmark of amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease, is formation of inclusion bodies (IBs) from misfolded proteins in neuronal cells. TAR RNA/DNA-binding protein 43 kDa (TDP43) is an ALS-causative protein forming IBs in ALS patients. The relation between localization of the IBs and neurotoxicity remains largely unknown. We characterized aggregation of fluorescently tagged TDP43 and its carboxyl-terminal fragments (CTFs) by analytical fluorescence imaging techniques. Quantitative time-lapse analysis in individual live cells showed that fluorescent-protein-tagged TDP43 was cleaved and a 35 kDa TDP43 CTF (TDP35) formed ubiquitin (Ub)-negative cytoplasmic IBs. Although TDP35 formed mildly toxic Ub-negative IBs in the cytoplasm, TDP25, another type of a TDP43 CTF, efficiently formed sufficiently toxic Ub-positive IBs. One-or two-color fluorescence correlation spectroscopy (FCS/FCCS) revealed that coaggregation of TDP25 with TDP43 was initiated by depletion of the RNA that binds to TDP25. Moreover, nuclear localization tagging TDP25 reduced the rate of neuronal cell death. These observations point to the need to elucidate the novel sequestration mechanism and details of the toxicity of the misfolded and aggregation-prone TDP43 CTFs (as well as the RNA binding and nuclear retention) in order to identify possible preventive interventions against ALS

In small cell lung cancer patients treated with RRx-001, a downregulator of CD47, decreased expression of PD-L1 on circulating tumor cells significantly correlates with clinical benefit.

BackgroundSmall cell lung cancer (SCLC) is the most aggressive lung tumor, characterized by a rapid doubling time and the development of widespread metastases, for which immune checkpoint inhibitors have been approved to overcome T cell anergy. In light of its dismal prognosis, and lack of curative options, new therapies for extensive-disease SCLC are desperately needed.MethodsRRx-001 is a small molecule Myc inhibitor and down-regulates CD47 expression on tumor cells. We evaluated the programmed death-ligand 1 (PD-L1) status of circulating tumor cells (CTCs) pre and post RRx-001 treatment in a phase 2 clinical trial, called QUADRUPLE THREAT, where patients with previously treated SCLC received RRx-001 in combination with a platinum doublet. The trial was registered with ClinicalTrials.gov, number NCT02489903. Fourteen patients with SCLC were analyzed to investigate the association between clinical outcome and PD-L1 expression on CTCs pre and post RRx-001. The correlation between the binary clinical outcome (clinical benefit vs. progressive disease) and the change of PD-L1 expression on CTCs after RRx-001 was analyzed using a logistic regression adjusting for baseline PD-L1 expression.ResultsThe logistic model McFadden goodness of fit score was 0.477. The logistic model analyzing the association between decreased PD-L1 expression on CTCs after RRx-001 and response to reintroduced platinum doublet had an approximate 92.8% accuracy in its prediction of clinical benefit. The estimated receiver operating characteristic (ROC) displayed a ROC area under the curve (AUC) of 0.93 (95% confidence interval, 0.78-0.99).ConclusionsThese results suggest that PD-L1 expression on CTCs decreased after RRx-001 was significantly correlated with response to reintroduced platinum-based doublet therapy. Monitoring PD-L1 expression on CTCs during RRx-001 treatment may serve as a biomarker to predict response to RRx-001-based cancer therapy

Generation of Large Numbers of Antigen-Expressing Human Dendritic Cells Using CD14-ML Technology

<div><p>We previously reported a method to expand human monocytes through lentivirus-mediated introduction of cMYC and BMI1, and we named the monocyte-derived proliferating cells, CD14-ML. CD14-ML differentiated into functional DC (CD14-ML-DC) upon addition of IL-4, resulting in the generation of a large number of DC. One drawback of this method was the extensive donor-dependent variation in proliferation efficiency. In the current study, we found that introduction of BCL2 or LYL1 along with cMYC and BMI1 was beneficial. Using the improved method, we obtained CD14-ML from all samples, regardless of whether the donors were healthy individuals or cancer patients. <i>In vitro</i> stimulation of peripheral blood T cells with CD14-ML-DC that were loaded with cancer antigen-derived peptides led to the establishment of CD4⁺ and CD8⁺ T cell lines that recognized the peptides. Since CD14-ML was propagated for more than 1 month, we could readily conduct genetic modification experiments. To generate CD14-ML-DC that expressed antigenic proteins, we introduced lentiviral antigen-expression vectors and subjected the cells to 2 weeks of culture for drug-selection and expansion. The resulting antigen-expressing CD14-ML-DC successfully induced CD8⁺ T cell lines that were reactive to CMVpp65 or MART1/MelanA, suggesting an application in vaccination therapy. Thus, this improved method enables the generation of a sufficient number of DC for vaccination therapy from a small amount of peripheral blood from cancer patients. Information on T cell epitopes is not necessary in vaccination with cancer antigen-expressing CD14-ML-DC; therefore, all patients, irrespective of HLA type, will benefit from anti-cancer therapy based on this technology.</p></div

Induction of CD8⁺ T cell lines that are reactive to antigens by CD14-ML-DC that express antigenic proteins.

<p>(A) The lentivirus constructs for CMVpp65 (EF-CMV-IP) and MART1 (EF-MART1-IP) are shown. CD14-ML were transduced with the lentivirus vector and cultured in the presence of puromycin (5 μg/ml) to select and expand the cell population carrying the transgene, resulting in the generation of CD14-ML/CMV and CD14-ML/MART1. (B) Expression of CMVpp65 by CD14-ML/CMV was analyzed by flow cytometric analysis. The staining profiles of the specific mAb (black lines) and isotype-matched control mAb (gray area) are shown. (C) CD14-ML-DC/CMV derived from a HLA-A*24:02-positive healthy donor were cultured with autologous CD8⁺ T cells. On day 9, the number of T cells reactive to the CMVpp65_341-349 peptide was analyzed by ELISPOT assay. The HIV-peptide was used as a control peptide. The results of the T cells before stimulation culture are shown (Day 0). (D) On day 9, the T cells were recovered and stained with an anti-CD8 mAb and a tetramer of HLA-A*24:02/CMVpp65_341-349 complex. The numbers in the figure indicate the percentage of the CD8⁺ T cells positively stained with the tetramer of the HLA-peptide complex. The results of the T cells before stimulation culture are also shown (Day 0). (E) CD8⁺ T cells obtained from an HLA-A*24:02-negative healthy donor were co-cultured with autologous CD14-ML-DC/CMV. On day 9, the number of IFN-γ producing CD8⁺ T cells was analyzed by ELISPOT assay, using CD14-ML and CD14-ML/CMV as stimulators. The results of the T cells before stimulation culture are also shown (Day 0). (F) Expression of MART1 by CD14-ML/MART1 was analyzed by flow cytometric analysis. The staining profiles of the specific mAbs (black lines) and isotype-matched control mAbs (gray area) are shown. (G) CD8⁺ T cells obtained from an HLA-A*02:01-positive healthy donor were co-cultured with autologous CD14-ML-DC/MART1 cells. On day 21, the frequency of CD8⁺ T cells reactive to MART1_26-35 was analyzed by ELISPOT assay. The HIV-peptide was used as a control peptide. The results of the T cells before stimulation culture are also shown (Day 0). (H) On day 21, the T cells were recovered and stained with an anti-CD8 mAb and HLA-A*02:01/MART1_26-35 dextramer. The numbers in the figure indicate the percentage of the CD8⁺ T cells that were positively stained with the dextramer of the HLA-peptide complex. The results of the T cells before stimulation culture are also shown (Day 0). (I) CD8⁺ T cells obtained from an HLA-A*02:01-negative healthy donor were co-cultured with autologous CD14-ML-DC/MART1. On day 21, the frequency of CD8⁺ T cells reactive to MART1 was analyzed by ELISPOT assay, using CD14-ML-DC and CD14-ML-DC/MART1 as stimulators. The results of the T cells before stimulation culture are also shown (Day 0).</p

Morphology of CD14-ML and CD14-ML-DC generated by the current procedure.

<p>(A) Phase-contrast images of live cells (left) and cytospin samples stained with May–Grünwald Giemsa (right) of the human monocytes and monocyte-derived myeloid cell lines (CD14-ML) are shown. (B) Morphology of OK432-stimulated mo-DC and CD14-ML-DC are shown. mo-DC and CD14-ML-DC were stimulated with OK432 for 2 days and subjected to microscopic analysis. The data are representative of 2 experiments.</p