Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
57
result(s) for
"Cam, Maggie"
Sort by:
Identification of essential genes for cancer immunotherapy
Somatic gene mutations can alter the vulnerability of cancer cells to T-cell-based immunotherapies. Here we perturbed genes in human melanoma cells to mimic loss-of-function mutations involved in resistance to these therapies, by using a genome-scale CRISPR–Cas9 library that consisted of around 123,000 single-guide RNAs, and profiled genes whose loss in tumour cells impaired the effector function of CD8
+
T cells. The genes that were most enriched in the screen have key roles in antigen presentation and interferon-γ signalling, and correlate with cytolytic activity in patient tumours from The Cancer Genome Atlas. Among the genes validated using different cancer cell lines and antigens, we identified multiple loss-of-function mutations in
APLNR
, encoding the apelin receptor, in patient tumours that were refractory to immunotherapy. We show that APLNR interacts with JAK1, modulating interferon-γ responses in tumours, and that its functional loss reduces the efficacy of adoptive cell transfer and checkpoint blockade immunotherapies in mouse models. Our results link the loss of essential genes for the effector function of CD8
+
T cells with the resistance or non-responsiveness of cancer to immunotherapies.
The authors describe a two-cell-type CRISPR screen to identify tumour-intrinsic genes that regulate the sensitivity of cancer cells to effector T cell function.
CRISPR screen identifies genes driving resistance to cancer immunotherapy
Some mutations in cancer cells make them resistant to immunotherapy. Nicholas Restifo and colleagues designed a 'two-cell-type' CRISPR–Cas9 screen to identify tumour-intrinsic genetic mutations associated with the sensitivity of melanoma cells to effector T cell function. The candidate genes identified included mediators of MHC class I antigen presentation and genes unknown to be involved in these immunity processes. The authors highlight the interaction between T-cell-secreted apelin and its receptor APLNR on tumour cells as a node for potent T-cell-mediated killing of cancer cells.
Journal Article
Extracellular matrix stiffness and cell contractility control RNA localization to promote cell migration
Numerous RNAs are enriched within cellular protrusions, but the underlying mechanisms are largely unknown. We had shown that the APC (adenomatous polyposis coli) protein controls localization of some RNAs at protrusions. Here, using protrusion-isolation schemes and RNA-Seq, we find that RNAs localized in protrusions of migrating fibroblasts can be distinguished in two groups, which are differentially enriched in distinct types of protrusions, and are additionally differentially dependent on APC. APC-dependent RNAs become enriched in high-contractility protrusions and, accordingly, their localization is promoted by increasing stiffness of the extracellular matrix. Dissecting the underlying mechanism, we show that actomyosin contractility activates a RhoA-mDia1 signaling pathway that leads to formation of a detyrosinated-microtubule network, which in turn is required for localization of APC-dependent RNAs. Importantly, a competition-based approach to specifically mislocalize APC-dependent RNAs suggests that localization of the APC-dependent RNA subgroup is functionally important for cell migration.
Adenomatous polyposis coli (APC) regulates the localization of some mRNAs at cellular protrusions but the underlying mechanisms and functional roles are not known. Here the authors show that APC-dependent RNAs are enriched in contractile protrusions, via detyrosinated microtubules, and enhance cell migration.
Journal Article
Germline HABP2 Mutation Causing Familial Nonmedullary Thyroid Cancer
A kindred has been identified with a mutation in
HABP2
that has a dominant-negative function and causes nonmedullary thyroid cancer in heterozygotes.
Thyroid cancer is common in the United States, with more than 62,000 cases projected in 2015. Thyroid cancers of follicular-cell origin account for more than 95% of all cases of thyroid cancer, with the remaining cancers originating from parafollicular cells (medullary thyroid cancer). Familial nonmedullary thyroid cancer, which accounts for 3 to 9% of all cases of thyroid cancer, has an autosomal dominant pattern of inheritance.
1
,
2
It may be syndromic, occurring as a component of one of the familial cancer syndromes (familial adenomatous polyposis, Gardner’s syndrome, Cowden’s disease, Carney complex type 1, Werner’s syndrome, and the DICER1 syndrome) for . . .
Journal Article
The long noncoding RNA lnc-FANCI-2 intrinsically restricts RAS signaling in human papillomavirus type 16-infected cervical cancer cells
Increased expression of lnc-FANCI-2, a newly discovered long noncoding RNA, is associated with cervical lesion progression from cervical intraepithelial neoplasia stage 1 (CIN1, low grade), CIN2–3 (high grade), to cervical cancer. Viral oncoprotein E7 of high-risk human papillomaviruses (HR-HPVs) and host transcription factor YY1 are two major factors promoting lnc-FANCI-2 expression. Using CRISPR-Cas9 technology, we knocked out the expression of lnc-FANCI-2 in the HPV16-positive cervical cancer cell line, CaSki cells. The selected knockout (KO) single-cell clones displayed altered cell morphology and proliferation with changes of cellular soluble receptors, but normal HPV16 E6 and E7 expression. Relative to the parental cells, lnc-FANCI-2 KO cells exhibited significantly increased RAS signaling and epithelial-mesenchymal transition, but decreased response to IFN signaling, along with increased p-Akt and p-Erk1/2 (two RAS signaling effectors), IGFBP3, MCAM, VIM, and CCND2 (cyclin D2) and decreased expression of RAC3. lnc-FANCI-2 in CaSki interacts with cellular proteins H13, HNRH1, K1H1, MAP4K4, and RNPS1. MAP4K4 knockdown led to enhance the expression of p-Erk1/2 and p-Akt. High lnc-FANCI-2 and low MCAM levels in cervical cancer tissues were found to be associated with patients’ survival. A key function of lnc-FANCI-2 intrinsically regulates RAS signaling to impact cervical lesion progression and cervical cancer prognosis.
Journal Article
Genome-wide regulation of KSHV RNA splicing by viral RNA-binding protein ORF57
RNA splicing plays an essential role in the expression of eukaryotic genes. We previously showed that KSHV ORF57 is a viral splicing factor promoting viral lytic gene expression. In this report, we compared the splicing profile of viral RNAs in BCBL-1 cells carrying a wild-type (WT) versus the cells containing an ORF57 knock-out (57KO) KSHV genome during viral lytic infection. Our analyses of viral RNA splice junctions from RNA-seq identified 269 RNA splicing events in the WT and 255 in the 57KO genome, including the splicing events spanning large parts of the viral genome and the production of vIRF4 circRNAs. No circRNA was detectable from the PAN region. We found that the 57KO alters the RNA splicing efficiency of targeted viral RNAs. Two most susceptible RNAs to ORF57 splicing regulation are the K15 RNA with eight exons and seven introns and the bicistronic RNA encoding both viral thymidylate synthase (ORF70) and membrane-associated E3-ubiquitin ligase (K3). ORF57 inhibits splicing of both K15 introns 1 and 2. ORF70/K3 RNA bears two introns, of which the first intron is within the ORF70 coding region as an alternative intron and the second intron in the intergenic region between the ORF70 and K3 as a constitutive intron. In the WT cells expressing ORF57, most ORF70/K3 transcripts retain the first intron to maintain an intact ORF70 coding region. In contrast, in the 57KO cells, the first intron is substantially spliced out. Using a minigene comprising of ORF70/K3 locus, we further confirmed ORF57 regulation of ORF70/K3 RNA splicing, independently of other viral factors. By monitoring protein expression, we showed that ORF57-mediated retention of the first intron leads to the expression of full-length ORF70 protein. The absence of ORF57 promotes the first intron splicing and expression of K3 protein. Altogether, we conclude that ORF57 regulates alternative splicing of ORF70/K3 bicistronic RNA to control K3-mediated immune evasion and ORF70 participation of viral DNA replication in viral lytic infection.
Journal Article
A spatial map of hepatic mitochondria uncovers functional heterogeneity shaped by nutrient-sensing signaling
In the liver, mitochondria are exposed to different concentrations of nutrients due to their spatial positioning across the periportal and pericentral axis. How the mitochondria sense and integrate these signals to respond and maintain homeostasis is not known. Here, we combine intravital microscopy, spatial proteomics, and functional assessment to investigate mitochondrial heterogeneity in the context of liver zonation. We find that periportal and pericentral mitochondria are morphologically and functionally distinct; beta-oxidation is elevated in periportal regions, while lipid synthesis is predominant in the pericentral mitochondria. In addition, comparative phosphoproteomics reveals spatially distinct patterns of mitochondrial composition and potential regulation via phosphorylation. Acute pharmacological modulation of nutrient sensing through AMPK and mTOR shifts mitochondrial phenotypes in the periportal and pericentral regions, linking nutrient gradients across the lobule and mitochondrial heterogeneity. This study highlights the role of protein phosphorylation in mitochondrial structure, function, and overall homeostasis in hepatic metabolic zonation. These findings have important implications for liver physiology and disease.
Kang et al. reveal structural and functional differences in mitochondria across the hepatic lobule. Mitochondrial distinct phosphoproteome influences their functions highlighting how nutrient availability helps to shape mitochondria zonation.
Journal Article
Reversal of the T cell immune system reveals the molecular basis for T cell lineage fate determination in the thymus
T cell specificity and function are linked during development, as MHC-II-specific TCR signals generate CD4 helper T cells and MHC-I-specific TCR signals generate CD8 cytotoxic T cells, but the basis remains uncertain. We now report that switching coreceptor proteins encoded by Cd4 and Cd8 gene loci functionally reverses the T cell immune system, generating CD4 cytotoxic and CD8 helper T cells. Such functional reversal reveals that coreceptor proteins promote the helper-lineage fate when encoded by Cd4, but promote the cytotoxic-lineage fate when encoded in Cd8—regardless of the coreceptor proteins each locus encodes. Thus, T cell lineage fate is determined by cis-regulatory elements in coreceptor gene loci and is not determined by the coreceptor proteins they encode, invalidating coreceptor signal strength as the basis of lineage fate determination. Moreover, we consider that evolution selected the particular coreceptor proteins that Cd4 and Cd8 gene loci encode to avoid generating functionally reversed T cells because they fail to promote protective immunity against environmental pathogens.To determine how T cell lineage fates are determined in the thymus, Singer and colleagues generated ‘FlipFlop’ mice with a functionally reversed T cell immune system that distinguishes TCR signal strength versus TCR signal duration.
Journal Article
HPV oncogenes expressed from only one of multiple integrated HPV DNA copies drive clonal cell expansion in cervical cancer
Persistent oncogenic HPV infections lead to viral DNA integration into the human genome and the development of cervical, anogenital, and oropharyngeal cancers. The expression of the viral E6 and E7 oncogenes plays a key role in cell transformation and tumorigenesis. However, how E6 and E7 could be expressed from the integrated viral DNA which often lacks a viral polyadenylation signal in the cancer cells remains unknown. By analyzing the integrated HPV DNA sites and expressed HPV RNAs in cervical cancer tissues and cell lines, we show that HPV oncogenes are expressed from only one of multiple chromosomal HPV DNA integrated copies. A host polyadenylation signal downstream of the integrated viral DNA is used for polyadenylation and stabilization of the virus-host chimeric RNAs, making the oncogenic transcripts targetable by siRNAs. This observation provides further understanding of the tumorigenic mechanism of HPV integration and suggests possible therapeutic strategies for the development of precision medicine for HPV cancers.
Journal Article
Myc controls a distinct transcriptional program in fetal thymic epithelial cells that determines thymus growth
Interactions between thymic epithelial cells (TEC) and developing thymocytes are essential for T cell development, but molecular insights on TEC and thymus homeostasis are still lacking. Here we identify distinct transcriptional programs of TEC that account for their age-specific properties, including proliferation rates, engraftability and function. Further analyses identify Myc as a regulator of fetal thymus development to support the rapid increase of thymus size during fetal life. Enforced Myc expression in TEC induces the prolonged maintenance of a fetal-specific transcriptional program, which in turn extends the growth phase of the thymus and enhances thymic output; meanwhile, inducible expression of Myc in adult TEC similarly promotes thymic growth. Mechanistically, this Myc function is associated with enhanced ribosomal biogenesis in TEC. Our study thus identifies age-specific transcriptional programs in TEC, and establishes that Myc controls thymus size.
Thymic epithelial cells (TEC) are essential for the maturation of functional T cells, while thymus size is proportional to the overall output efficiency. Here the authors show, using transcriptome analyses, that mouse fetal TEC maintain a Myc-dependent genetic program to ensure a rapid increase in thymus size, and thereby expedited T cell generation.
Journal Article