TERRAs are long non-coding RNAs generated from the telomeres. Lack of TERRA knockout models has hampered understanding TERRAs' functions. We recently identified chromosome 20q as one of the main ...origins of human TERRAs, allowing us to generate the first 20q-TERRA knockout models and to demonstrate that TERRAs are essential for telomere length maintenance and protection. Here, we use ALT 20q-TERRA knockout cells to address a direct role of TERRAs in telomeric heterochromatin formation. We find that 20q-TERRAs are essential for the establishment of H3K9me3, H4K20me3, and H3K27me3 heterochromatin marks at telomeres. At the mechanistic level, we find that TERRAs bind to PRC2, responsible for catalyzing H3K27 tri-methylation, and that its localization to telomeres is TERRA-dependent. We further demonstrate that PRC2-dependent H3K27me3 at telomeres is required for the establishment of H3K9me3, H4K20me3, and HP1 binding at telomeres. Together, these findings demonstrate an important role for TERRAs in telomeric heterochromatin assembly.
CAR-T-cell therapy against MM currently shows promising results, but usually with serious toxicities. CAR-NK cells may exert less toxicity when redirected against resistant myeloma cells. CARs can be ...designed through the use of receptors, such as NKG2D, which recognizes a wide range of ligands to provide broad target specificity. Here, we test this approach by analyzing the antitumor activity of activated and expanded NK cells (NKAE) and CD45RA
T cells from MM patients that were engineered to express an NKG2D-based CAR. NKAE cells were cultured with irradiated Clone9.mbIL21 cells. Then, cells were transduced with an NKG2D-4-1BB-CD3z-CAR. CAR-NKAE cells exhibited no evidence of genetic abnormalities. Although memory T cells were more stably transduced, CAR-NKAE cells exhibited greater in vitro cytotoxicity against MM cells, while showing minimal activity against healthy cells. In vivo, CAR-NKAE cells mediated highly efficient abrogation of MM growth, and 25% of the treated mice remained disease free. Overall, these results demonstrate that it is feasible to modify autologous NKAE cells from MM patients to safely express a NKG2D-CAR. Additionally, autologous CAR-NKAE cells display enhanced antimyeloma activity demonstrating that they could be an effective strategy against MM supporting the development of NKG2D-CAR-NK-cell therapy for MM.
Podoplanin is a small membrane mucin expressed in tumors associated with malignant progression. It is enriched at cell-surface protrusions where it colocalizes with members of the ERM (ezrin, ...radixin, moesin) protein family. Here, we found that human podoplanin directly interacts with ezrin (and moesin) in vitro and in vivo through a cluster of basic amino acids within its cytoplasmic tail, mainly through a juxtamembrane dipeptide RK. Podoplanin induced an epithelial-mesenchymal transition in MDCK cells linked to the activation of RhoA and increased cell migration and invasiveness. Fluorescence time-lapse video observations in migrating cells indicate that podoplanin might be involved in ruffling activity as well as in retractive processes. By using mutant podoplanin constructs fused to green fluorescent protein we show that association of the cytoplasmic tail with ERM proteins is required for upregulation of RhoA activity and epithelial-mesenchymal transition. Furthermore, expression of either a dominant-negative truncated variant of ezrin or a dominant-negative mutant form of RhoA blocked podoplanin-induced RhoA activation and epithelial-mesenchymal transition. These results provide a mechanistic basis to understand the role of podoplanin in cell migration or invasiveness.
Reprogramming of adult cells to generate induced pluripotent stem cells (iPS cells) has opened new therapeutic opportunities; however, little is known about the possibility of in vivo reprogramming ...within tissues. Here we show that transitory induction of the four factors Oct4, Sox2, Klf4 and c-Myc in mice results in teratomas emerging from multiple organs, implying that full reprogramming can occur in vivo. Analyses of the stomach, intestine, pancreas and kidney reveal groups of dedifferentiated cells that express the pluripotency marker NANOG, indicative of in situ reprogramming. By bone marrow transplantation, we demonstrate that haematopoietic cells can also be reprogrammed in vivo. Notably, reprogrammable mice present circulating iPS cells in the blood and, at the transcriptome level, these in vivo generated iPS cells are closer to embryonic stem cells (ES cells) than standard in vitro generated iPS cells. Moreover, in vivo iPS cells efficiently contribute to the trophectoderm lineage, suggesting that they achieve a more plastic or primitive state than ES cells. Finally, intraperitoneal injection of in vivo iPS cells generates embryo-like structures that express embryonic and extraembryonic markers. We conclude that reprogramming in vivo is feasible and confers totipotency features absent in standard iPS or ES cells. These discoveries could be relevant for future applications of reprogramming in regenerative medicine.
CRANAD‐2 is a fluorogenic curcumin derivative used for near‐infrared detection and imaging in vivo of amyloid aggregates, which are involved in neurodegenerative diseases. We explore the performance ...of CRANAD‐2 in two super‐resolution imaging techniques, namely stimulated emission depletion (STED) and single‐molecule localization microscopy (SMLM), with markedly different fluorophore requirements. By conveniently adapting the concentration of CRANAD‐2, which transiently binds to amyloid fibrils, we show that it performs well in both techniques, achieving a resolution in the range of 45–55 nm. Correlation of SMLM with atomic force microscopy (AFM) validates the resolution of fine features in the reconstructed super‐resolved image. The good performance and versatility of CRANAD‐2 provides a powerful tool for near‐infrared nanoscopic imaging of amyloids in vitro and in vivo.
We test the performance of CRANAD‐2 in stimulated emission depletion (STED) and single‐molecule localization microscopy (SMLM), two super‐resolution techniques with typically divergent fluorophore requirements. By conveniently adapting the concentration of CRANAD‐2, which transiently binds to amyloid fibrils, we show that it performs well in both techniques, achieving a resolution in the range of 45–55 nm.
Chronic inflammation increases the risk of developing one of several types of cancer. Inflammatory responses are currently thought to be controlled by mechanisms that rely on transcriptional networks ...that are distinct from those involved in cell differentiation. The orphan nuclear receptor NR5A2 participates in a wide variety of processes, including cholesterol and glucose metabolism in the liver, resolution of endoplasmic reticulum stress, intestinal glucocorticoid production, pancreatic development and acinar differentiation. In genome-wide association studies, single nucleotide polymorphisms in the vicinity of NR5A2 have previously been associated with the risk of pancreatic adenocarcinoma. In mice, Nr5a2 heterozygosity sensitizes the pancreas to damage, impairs regeneration and cooperates with mutant Kras in tumour progression. Here, using a global transcriptomic analysis, we describe an epithelial-cell-autonomous basal pre-inflammatory state in the pancreas of Nr5a2
mice that is reminiscent of the early stages of pancreatitis-induced inflammation and is conserved in histologically normal human pancreases with reduced expression of NR5A2 mRNA. In Nr5a2
mice, NR5A2 undergoes a marked transcriptional switch, relocating from differentiation-specific to inflammatory genes and thereby promoting gene transcription that is dependent on the AP-1 transcription factor. Pancreatic deletion of Jun rescues the pre-inflammatory phenotype, as well as binding of NR5A2 to inflammatory gene promoters and the defective regenerative response to damage. These findings support the notion that, in the pancreas, the transcriptional networks involved in differentiation-specific functions also suppress inflammatory programmes. Under conditions of genetic or environmental constraint, these networks can be subverted to foster inflammation.
Eukaryotic cells rely on several mechanisms to ensure that the genome is duplicated precisely once in each cell division cycle, preventing DNA over-replication and genomic instability. Most of these ...mechanisms limit the activity of origin licensing proteins to prevent the reactivation of origins that have already been used. Here, we have investigated whether additional controls restrict the extension of re-replicated DNA in the event of origin re-activation. In a genetic screening in cells forced to re-activate origins, we found that re-replication is limited by RAD51 and enhanced by FBH1, a RAD51 antagonist. In the presence of chromatin-bound RAD51, forks stemming from re-fired origins are slowed down, leading to frequent events of fork reversal. Eventual re-initiation of DNA synthesis mediated by PRIMPOL creates ssDNA gaps that facilitate the partial elimination of re-duplicated DNA by MRE11 exonuclease. In the absence of RAD51, these controls are abrogated and re-replication forks progress much longer than in normal conditions. Our study uncovers a safeguard mechanism to protect genome stability in the event of origin reactivation.
Synopsis
Several mechanisms prevent DNA over-replication in eukaryotic cells. Here, a genetic screen reveals an additional role for RAD51 in slowing down and reversal of re-replication forks in the event of origin re-firing.
RAD51 protein bound to newly replicated DNA hinders re-replication when origins are re-activated.
Re-replicated forks undergo frequent fork reversal and rely on PRIMPOL-mediated repriming to maintain DNA synthesis.
PRIMPOL-generated ssDNA gaps allow MRE11 exonuclease to access and degrade re-duplicated DNA.
The RAD51-PRIMPOL-MRE11 axis serves as a safeguard against DNA over-replication.
RAD51-dependent slow-down and reversal of re-replication forks makes them susceptible to processing via PRIMPOL and MRE11, thereby protecting genome integrity upon origin re-firing.
Pharmacological activation of cannabinoid receptors elicits antitumoral responses in different cancer models. However, the biological role of these receptors in tumor physio-pathology is still ...unknown.
We analyzed CB2 cannabinoid receptor protein expression in two series of 166 and 483 breast tumor samples operated in the University Hospitals of Kiel, Tübingen, and Freiburg between 1997 and 2010 and CB2 mRNA expression in previously published DNA microarray datasets. The role of CB2 in oncogenesis was studied by generating a mouse line that expresses the human V-Erb-B2 Avian Erythroblastic Leukemia Viral Oncogene Homolog 2 (HER2) rat ortholog (neu) and lacks CB2 and by a variety of biochemical and cell biology approaches in human breast cancer cells in culture and in vivo, upon modulation of CB2 expression by si/shRNAs and overexpression plasmids. CB2-HER2 molecular interaction was studied by colocalization, coimmunoprecipitation, and proximity ligation assays. Statistical tests were two-sided.
We show an association between elevated CB2 expression in HER2+ breast tumors and poor patient prognosis (decreased overall survival, hazard ratio HR = 0.29, 95% confidence interval CI = 0.09 to 0.71, P = .009) and higher probability to suffer local recurrence (HR = 0.09, 95% CI = 0.049 to 0.54, P = .003) and to develop distant metastases (HR = 0.33, 95% CI = 0.13 to 0.75, P = .009). We also demonstrate that genetic inactivation of CB2 impairs tumor generation and progression in MMTV-neu mice. Moreover, we show that HER2 upregulates CB2 expression by activating the transcription factor ELK1 via the ERK cascade and that an increased CB2 expression activates the HER2 pro-oncogenic signaling at the level of the tyrosine kinase c-SRC. Finally, we show HER2 and CB2 form heteromers in cancer cells.
Our findings reveal an unprecedented role of CB2 as a pivotal regulator of HER2 pro-oncogenic signaling in breast cancer, and they suggest that CB2 may be a biomarker with prognostic value in these tumors.
is an excellent model to investigate fungal pathogenesis. This yeast can produce "titan cells," which are cells of an abnormally larger size that contribute to the persistence of the yeast in the ...host. In this work, we have used a new approach to characterize them by identifying drugs that inhibit this process. We have used a repurposing off-patent drug library, combined with an automatic method to image and analyze fungal cell size. In this way, we have identified many compounds that inhibit this transition. Interestingly, several compounds were antioxidants, allowing us to confirm that endogenous ROS and mitochondrial changes are important for titan cell formation. This work provides new evidence of the mechanisms required for titanization. Furthermore, the future characterization of the inhibitory mechanisms of the identified compounds by the scientific community will contribute to better understand the role of titan cells in virulence.
Glioblastoma multiforme (GBM) is a deadly and common brain tumor. Poor prognosis is linked to high proliferation and cell heterogeneity, including glioma stem cells (GSCs). Telomere genes are ...frequently mutated. The telomere binding protein TRF1 is essential for telomere protection, and for adult and pluripotent stem cells. Here, we find TRF1 upregulation in mouse and human GBM. Brain-specific Trf1 genetic deletion in GBM mouse models inhibited GBM initiation and progression, increasing survival. Trf1 deletion increased telomeric DNA damage and reduced proliferation and stemness. TRF1 chemical inhibitors mimicked these effects in human GBM cells and also blocked tumor sphere formation and tumor growth in xenografts from patient-derived primary GSCs. Thus, targeting telomeres throughout TRF1 inhibition is an effective therapeutic strategy for GBM.
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•TRF1 expression is increased in both human and mouse GBM•TRF1 inhibition impairs GBM initiation and progression in different mouse models•The mechanism involves telomeric DNA damage induction and reduced stemness•TRF1 chemical inhibitors inhibit xenograft growth from patient-derived primary GSCs
Bejarano et al. show that genetic or chemical inhibition of TRF1 increases telomeric DNA damage and reduces proliferation and stemness independent of telomere length. TRF1 inhibition also inhibits glioblastoma initiation and progression and prolongs survival in genetic and xenograft glioblastoma models.
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