The mammalian genome encodes thousands of long non-coding RNAs (lncRNAs) that are developmentally regulated and differentially expressed across tissues, suggesting possible roles in cellular differentiation. Despite this expression pattern, little is known about how lncRNAs influence lineage commitment at the molecular level. Here, we reveal that perturbation of an embryonic stem cell (ESC)-specific lncRNA, Pluripotency associated transcript 4 (Platr4), in ESCs directly influences the downstream meso/endoderm differentiation program without affecting pluripotency. We further show that Platr4 interacts with the TEA domain transcription factor 4 (Tead4) to regulate the expression of a downstream target gene crucial in the cardiac lineage program known as connective tissue growth factor (Ctgf). Importantly, Platr4 knockout mice exhibit myocardial atrophy, valve mucinous degenration associated with reduced cardiac output and sudden heart failure. Together, our findings provide evidence that Platr4 expression in undifferentiated ESCs is critical for downstream lineage differentiation, highlighting its importance in disease modeling and regenerative medicine.
Imaging defined aspects of functional tumor biology with bioluminescent reporter transgenes is a popular approach in preclinical drug development as it is sensitive, relatively high-throughput and low cost. However, the lack of internal controls subject functional bioluminescence to a number of unpredictable variables that reduce this powerful tool to semi-quantitative interpretation of large-scale effects. Here, we report the generation of sensitive and quantitative live reporters for two key measures of functional cancer biology and pharmacologic stress: the cell cycle and oxidative stress. We developed a two-colored readout, where two independent enzymes convert a common imaging substrate into spectrally distinguishable light. The signal intensity of one color is dependent upon the biological state, whereas the other color is constitutively expressed. The ratio of emitted colored light corrects the functional signal for independent procedural variables, substantially improving the robustness and interpretation of relatively low-fold changes in functional signal intensity after drug treatment. The application of these readouts in vitro is highly advantageous, as peak cell response to therapy can now be readily visualized for single or combination treatments and not simply assessed at an arbitrary and destructive timepoint. Spectral imaging in vivo can be challenging, but we also present evidence to show that the reporters can work in this context as well. Collectively, the development and validation of these internally controlled reporters allow researchers to robustly and dynamically visualize tumor cell biology in response to treatment. Given the prevalence of bioluminescence imaging, this presents significant and much needed opportunities for preclinical therapeutic development.
Imaging defined aspects of functional tumor biology with bioluminescent reporter transgenes is a popular approach amongst the research community in drug development, as it is sensitive, relatively high-throughput and low cost. However, the lack of internal controls subject functional bioluminescence to a number of unpredictable variables that reduce this powerful tool to semi-quantitative interpretation of large-scale effects. Here we report the generation of sensitive and quantitative live reporters for two key measures of functional cancer biology and pharmacologic stress: the cell cycle and oxidative stress. We developed a two-colored readout, where two independent enzymes convert a common imaging substrate into spectrally distinguishable light. The signal intensity of one color is dependent upon biological state, whereas the other color is constitutively expressed. The ratio of emitted colored light corrects the functional signal for independent procedural variables, substantially improving the robustness and interpretation of relatively low-fold changes in functional signal intensity after drug treatment. The application of these readouts in vitro is highly advantageous, as peak cell response to therapy can now be readily visualized for single or combination treatments and not simply assessed at an arbitrary and destructive timepoint. Spectral imaging in vivo can be challenging, but we also present evidence to show that the reporters can work in this context as well. Collectively, the development and validation of these internally controlled reporters allow researchers to robustly and dynamically visualize tumor cell biology in response to treatment. Given the prevalence of bioluminescence imaging, this presents significant and much needed opportunities for preclinical therapeutic development.
Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy, as 90% of patients do not survive beyond five years from diagnosis. This dismal prognosis is largely due to the advanced stage of the disease at diagnosis, which precludes potentially curative surgical resection. Although early detection strategies hold significant promise for improving patient outcomes, there is still no accurate diagnostic tool to detect incipient PDAC. Here, we sought to develop antibodies for the early detection of PDAC by positron-emission tomography (PET) imaging. Accordingly, we establish a pipeline to generate novel tumor-specific monoclonal antibodies (mAbs) against cell-surface proteins of PDAC patient-derived organoids (PDOs). We identify a panel of 16 tumor organoid-binding antibodies (TOBi-bodies) that display high reactivity to human PDAC tissues but not to matched adjacent normal pancreas. We then employ biochemical, flow cytometric, mass spectrometric, and CRISPR/Cas9-mediated knockout methods to determine the cognate antigens of these TOBi-bodies. We identify two mAbs that bind to tumor-specific variants of the surface protein CEACAM6 and show minimal binding to normal tissues. PET imaging in mouse models using these TOBi-bodies enables the detection of incipient human organoid-derived PDAC tumors that are rather undetectable by palpation or high-resolution ultrasound imaging techniques. We propose that further development of these mAbs as PET radiotracers could facilitate the early detection and accurate staging of PDAC.
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