Authors: Oldfield AJ, Henriques T, Kumar D, Burkholder AB, Cinghu S, Paulet D, Bennett BD, Yang P, Scruggs BS, Lavender CA, Rivals E, Adelman K, Jothi R
Journal: Nat Commun. 2019 Jul 11;10(1):3072. doi: 10.1038/s41467-019-10905-7.
Faithful transcription initiation is critical for accurate gene expression, yet the mechanisms underlying specific transcription start site (TSS) selection in mammals remain unclear. Here, we show that the histone-fold domain protein NF-Y, a ubiquitously expressed transcription factor, controls the fidelity of transcription initiation at gene promoters in mouse embryonic stem cells. We report that NF-Y maintains the region upstream of TSSs in a nucleosome-depleted state while simultaneously protecting this accessible region against aberrant and/or ectopic transcription initiation. We find that loss of NF-Y binding in mammalian cells disrupts the promoter chromatin landscape, leading to nucleosomal encroachment over the canonical TSS. Importantly, this chromatin rearrangement is accompanied by upstream relocation of the transcription pre-initiation complex and ectopic transcription initiation. Further, this phenomenon generates aberrant extended transcripts that undergo translation, disrupting gene expression profiles. These results suggest NF-Y is a central player in TSS selection in metazoans and highlight the deleterious consequences of inaccurate transcription initiation.
Authors: Miller TW, Amason JD, Garcin ED, Lamy L, Dranchak PK, Macarthur R, Braisted J, Rubin JS, Burgess TL, Farrell CL, Roberts DD, Inglese J
Journal: PLoS One. 2019 Jul 5;14(7):e0218897. doi: 10.1371/journal.pone.0218897. eCollection 2019.
CD47 is an immune checkpoint molecule that downregulates key aspects of both the innate and adaptive anti-tumor immune response via its counter receptor SIRPα, and it is expressed at high levels in a wide variety of tumor types. This has led to the development of biologics that inhibit SIRPα engagement including humanized CD47 antibodies and a soluble SIRPα decoy receptor that are currently undergoing clinical trials. Unfortunately, toxicological issues, including anemia related to on-target mechanisms, are barriers to their clinical advancement. Another potential issue with large biologics that bind CD47 is perturbation of CD47 signaling through its high-affinity interaction with the matricellular protein thrombospondin-1 (TSP1). One approach to avoid these shortcomings is to identify and develop small molecule molecular probes and pretherapeutic agents that would (1) selectively target SIRPα or TSP1 interactions with CD47, (2) provide a route to optimize pharmacokinetics, reduce on-target toxicity and maximize tissue penetration, and (3) allow more flexible routes of administration. As the first step toward this goal, we report the development of an automated quantitative high-throughput screening (qHTS) assay platform capable of screening large diverse drug-like chemical libraries to discover novel small molecules that inhibit CD47-SIRPα interaction. Using time-resolved Förster resonance energy transfer (TR-FRET) and bead-based luminescent oxygen channeling assay formats (AlphaScreen), we developed biochemical assays, optimized their performance, and individually tested them in small-molecule library screening. Based on performance and low false positive rate, the LANCE TR-FRET assay was employed in a ~90,000 compound library qHTS, while the AlphaScreen oxygen channeling assay served as a cross-validation orthogonal assay for follow-up characterization. With this multi-assay strategy, we successfully eliminated compounds that interfered with the assays and identified five compounds that inhibit the CD47-SIRPα interaction; these compounds will be further characterized and later disclosed. Importantly, our results validate the large library qHTS for antagonists of CD47-SIRPα interaction and suggest broad applicability of this approach to screen chemical libraries for other protein-protein interaction modulators.
Authors: Khincha PP, Best AF, Fraumeni JF Jr, Loud JT, Savage SA, Achatz MI
Journal: Eur J Cancer. 2019 Jul;116:199-206. doi: 10.1016/j.ejca.2019.05.005.
Li-Fraumeni syndrome (LFS) is a rare autosomal dominant cancer predisposition syndrome with exceptionally high lifetime cancer risks, caused primarily by germline TP53 variants. Early-onset breast cancer is the most common cancer in women with LFS. Associations between female reproductive factors and breast cancer risk have been widely studied in the general population and BRCA1/2 mutation carriers but not in LFS. We evaluated whether reproductive factors are associated with breast cancer in LFS. Questionnaire data were collected for 152 women with confirmed germline TP53 variants enrolled in the National Cancer Institute's LFS study (NCT01443468); of which, 85 had breast cancer, confirmed by pathology/medical reports. Fisher's exact test and Cox proportional hazards were used to calculate the effect of reproductive factors on breast cancer risk. Lifetime breastfeeding for at least 7 months was associated with lower breast cancer risk (hazard ratio [HR] 0.57, p = 0.05). Parity did not independently change breast cancer risk (HR 1.08, p = 0.8) but suggested an increased risk with older age at first live birth (HR 2.14, p = 0.05). Age at menarche (HR 1.09, p = 0.24) and use of oral contraceptives (HR 0.88; p = 0.7) did not significantly affect breast cancer risk. In this first study of reproductive factors and breast cancer in women with LFS, breastfeeding was observed to be protective against breast cancer risk, especially with at least 7 months of lifetime breastfeeding. Older age at first live birth was suggested to slightly increase breast cancer risk. Larger prospective studies of reproductive factors are warranted in women with LFS before making definitive clinical recommendations.
Authors: Rubin JE, Smith JC
Journal: PLoS Comput Biol. 2019 Jul 30;15(7):e1006860. doi: 10.1371/journal.pcbi.1006860. [Epub ahead of print]
A central issue in the study of the neural generation of respiratory rhythms is the role of the intrinsic pacemaking capabilities that some respiratory neurons exhibit. The debate on this issue has occurred in parallel to investigations of interactions among respiratory network neurons and how these contribute to respiratory behavior. In this computational study, we demonstrate how these two issues are inextricably linked. We use simulations and dynamical systems analysis to show that once a conditional respiratory pacemaker, which can be tuned across oscillatory and non-oscillatory dynamic regimes in isolation, is embedded into a respiratory network, its dynamics become masked: the network exhibits similar dynamical properties regardless of the conditional pacemaker node's tuning, and that node's outputs are dominated by network influences. Furthermore, the outputs of the respiratory central pattern generator as a whole are invariant to these changes of dynamical properties, which ensures flexible and robust performance over a wide dynamic range.
Authors: Yao C, Sun HW, Lacey NE, Ji Y, Moseman EA, Shih HY, Heuston EF, Kirby M, Anderson S, Cheng J, Khan O, Handon R, Reilley J, Fioravanti J, Hu J, Gossa S, Wherry EJ, Gattinoni L, McGavern DB, O'Shea JJ, Schwartzberg PL, Wu T
Journal: Nat Immunol. 2019 Jul;20(7):890-901. doi: 10.1038/s41590-019-0403-4.
Progenitor-like CD8+ T cells mediate long-term immunity to chronic infection and cancer and respond potently to immune checkpoint blockade. These cells share transcriptional regulators with memory precursor cells, including T cell-specific transcription factor 1 (TCF1), but it is unclear whether they adopt distinct programs to adapt to the immunosuppressive environment. By comparing the single-cell transcriptomes and epigenetic profiles of CD8+ T cells responding to acute and chronic viral infections, we found that progenitor-like CD8+ T cells became distinct from memory precursor cells before the peak of the T cell response. We discovered a coexpression gene module containing Tox that exhibited higher transcriptional activity associated with more abundant active histone marks in progenitor-like cells than memory precursor cells. Moreover, thymocyte selection-associated high mobility group box protein TOX (TOX) promoted the persistence of antiviral CD8+ T cells and was required for the programming of progenitor-like CD8+ T cells. Thus, long-term CD8+ T cell immunity to chronic viral infection requires unique transcriptional and epigenetic programs associated with the transcription factor TOX.
Authors: Tripathi BK, Anderman MF, Qian X, Zhou M, Wang D, Papageorge AG, Lowy DR
Journal: J Cell Biol. 2019 Jul 15. pii: jcb.201810098. doi: 10.1083/jcb.201810098.
SRC and ERK kinases control many cell biological processes that promote tumorigenesis by altering the activity of oncogenic and tumor suppressor proteins. We identify here a physiological interaction between DLC1, a focal adhesion protein and tumor suppressor, with SRC and ERK. The tumor suppressor function of DLC1 is attenuated by phosphorylation of tyrosines Y451 and Y701 by SRC, which down-regulates DLC1's tensin-binding and Rho-GAP activities. ERK1/2 phosphorylate DLC1 on serine S129, which increases both the binding of SRC to DLC1 and SRC-dependent phosphorylation of DLC1. SRC inhibitors exhibit potent antitumor activity in a DLC1-positive transgenic cancer model and a DLC1-positive tumor xenograft model, due to reactivation of the tumor suppressor activities of DLC1. Combined treatment of DLC1-positive tumors with SRC plus AKT inhibitors has even greater antitumor activity. Together, these findings indicate cooperation between the SRC, ERK1/2, and AKT kinases to reduce DLC1 Rho-GAP and tumor suppressor activities in cancer cells, which can be reactivated by the kinase inhibitors.
Authors: Dilthey AT, Jain C, Koren S, Phillippy AM
Journal: Nat Commun. 2019 Jul 11;10(1):3066. doi: 10.1038/s41467-019-10934-2.
Metagenomic sequence classification should be fast, accurate and information-rich. Emerging long-read sequencing technologies promise to improve the balance between these factors but most existing methods were designed for short reads. MetaMaps is a new method, specifically developed for long reads, capable of mapping a long-read metagenome to a comprehensive RefSeq database with >12,000 genomes in <16 GB or RAM on a laptop computer. Integrating approximate mapping with probabilistic scoring and EM-based estimation of sample composition, MetaMaps achieves >94% accuracy for species-level read assignment and r2 > 0.97 for the estimation of sample composition on both simulated and real data when the sample genomes or close relatives are present in the classification database. To address novel species and genera, which are comparatively harder to predict, MetaMaps outputs mapping locations and qualities for all classified reads, enabling functional studies (e.g. gene presence/absence) and detection of incongruities between sample and reference genomes.
Authors: Cui J, Zhang Q, Song Q, Wang H, Dmitriev P, Sun M, Cao X, Wang Y, Guo L, Indig I, Rosenblum J, Ji C, Cao D, Yang K, Gilbert MR, Yao Y, Zhuang Z
Journal: Neuro Oncol. 2019 Jul 4. pii: noz117. doi: 10.1093/neuonc/noz117. [Epub ahead of print]
BACKGROUND: Glioblastoma survival remains unchanged despite continuing therapeutic innovation. Herein, we aim to 1) develop CAR-T cells with a specificity to a unique antigen, carbonic anhydrase IX (CAIX), which is expressed in the hypoxic microenvironment characteristic of glioblastoma, and 2) demonstrate its efficacy with limited off-target effects.
METHODS: First we demonstrated expression of CAIX in patient-derived glioblastoma samples and available databases. CAR-T cells were generated against CAIX and efficacy was assessed in four glioblastoma cell lines and two glioblastoma stem cell lines. Cytotoxicity of anti-CAIX CAR-T cells was assessed via IFN-γ, TNF-α, and IL-2 levels when co-cultured with tumor cells. Finally, we assessed efficacy of direct intra-tumoral injection of the anti-CAIX CAR-T cells on an in vivo xenograft mouse model using the U251 fluorescent cell line. Tumor infiltrating lymphocyte analyses were performed.
RESULTS: We confirm that CAIX is highly expressed in glioblastoma from patients. We demonstrate that CAIX is a suitable target for CAR-T therapy using anti-CAIX CAR-T cells against glioblastoma in vitro and in vivo. In our mouse model, a 20% cure rate was observed without detectable systemic effects.
CONCLUSIONS: By establishing the specificity of CAIX under hypoxic conditions in glioblastoma and highlighting its efficacy as a target for CAR-T therapy, our data suggest that anti-CAIX CAR-T may be a promising strategy to treat glioblastoma. Direct intra-tumoral injection increases anti-CAIX CAR-T potency while limiting its off-target effects.
Authors: Dai DP, Prasad R, Strauss PR, Wilson SH
Journal: Sci Rep. 2019 Jul 9;9(1):9928. doi: 10.1038/s41598-019-45846-0.
DNA polymerase (Pol) β is a key enzyme in base excision repair (BER), an important repair system for maintaining genomic integrity. We previously reported the presence of a Pol β transcript containing exon α (105-nucleotide) in normal and colon cancer cell lines. The transcript carried an insertion between exons VI and VII and was predicted to encode a ~42 kDa variant of the wild-type 39 kDa enzyme. However, little is known about the biochemical properties of the exon α-containing Pol β (exon α Pol β) variant. Here, we first obtained evidence indicating expression of the 42 kDa exon α Pol β variant in mouse embryonic fibroblasts. The exon α Pol β variant was then overexpressed in E. coli, purified, and characterized for its biochemical properties. Kinetic studies of exon α Pol β revealed that it is deficient in DNA binding to gapped DNA, has strongly reduced polymerase activity and higher Km for dNTP during gap-filling. On the other hand, the 5'-dRP lyase activity of the exon α Pol β variant is similar to that of wild-type Pol β. These results indicate the exon α Pol β variant is base excision repair deficient, but does conduct 5'-trimming of a dRP group at the gap margin. Understanding the biological implications of this Pol β variant warrants further investigation.
Authors: Harly C, Kenney D, Ren G, Lai B, Raabe T, Yang Q, Cam MC, Xue HH, Zhao K, Bhandoola A
Journal: Nat Immunol. 2019 Jul 29. doi: 10.1038/s41590-019-0445-7.
Innate lymphoid cells (ILCs) play important functions in immunity and tissue homeostasis, but their development is poorly understood. Through the use of single-cell approaches, we examined the transcriptional and functional heterogeneity of ILC progenitors, and studied the precursor-product relationships that link the subsets identified. This analysis identified two successive stages of ILC development within T cellfactor 1-positive (TCF-1+) early innate lymphoid progenitors (EILPs), which we named 'specified EILPs' and 'committed EILPs'. Specified EILPs generated dendritic cells, whereas this potential was greatly decreased in committed EILPs. TCF-1 was dispensable for the generation of specified EILPs, but required for the generation of committed EILPs. TCF-1 used a pre-existing regulatory landscape established in upstream lymphoid precursors to bind chromatin in EILPs. Our results provide insight into the mechanisms by which TCF-1 promotes developmental progression of ILC precursors, while constraining their dendritic cell lineage potential and enforcing commitment to ILC fate.