The derivation of tissue-specific stem cells from human induced pluripotent stem cells (iPSCs) would have broad reaching implications for regenerative medicine. Here, we report the directed ...differentiation of human iPSCs into airway basal cells (“iBCs”), a population resembling the stem cell of the airway epithelium. Using a dual fluorescent reporter system (NKX2-1GFP;TP63tdTomato), we track and purify these cells as they first emerge as developmentally immature NKX2-1GFP+ lung progenitors and subsequently augment a TP63 program during proximal airway epithelial patterning. In response to primary basal cell medium, NKX2-1GFP+/TP63tdTomato+ cells display the molecular and functional phenotype of airway basal cells, including the capacity to self-renew or undergo multi-lineage differentiation in vitro and in tracheal xenografts in vivo. iBCs and their differentiated progeny model perturbations that characterize acquired and genetic airway diseases, including the mucus metaplasia of asthma, chloride channel dysfunction of cystic fibrosis, and ciliary defects of primary ciliary dyskinesia.
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•Directed differentiation of human iPSCs generates airway basal cells (“iBCs”)•iBCs self-renew and display multipotent differentiation in vitro and in vivo•By single-cell RNA-seq, iBCs are highly similar to adult primary airway basal cells•iBCs enable modeling of acquired and genetic airway diseases
Hawkins and colleagues report a directed differentiation protocol enabling the derivation of airway basal cells (“iBCs”) from human iPSCs. iBCs recapitulate hallmark stem cell properties of primary basal cells, including self-renewal and multi-lineage differentiation, thus enabling modeling of airway diseases in vitro and repopulation of tracheal xenografts in vivo.
Abstract Recent advances in genetics and neuropathology support the idea that amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTD) are two ends of a disease spectrum. Although ...several animal models have been developed to investigate the pathogenesis and disease progression in ALS and FTD, there are significant limitations that hamper our ability to connect these models with the neurodegenerative processes in human diseases. With the technical breakthrough in reprogramming biology, it is now possible to generate patient-specific induced pluripotent stem cells (iPSCs) and disease-relevant neuron subtypes. This review provides a comprehensive summary of studies that use iPSC-derived neurons to model ALS and FTD. We discuss the unique capabilities of iPSC-derived neurons that capture some key features of ALS and FTD, and underscore their potential roles in drug discovery. There are, however, several critical caveats that require improvements before iPSC-derived neurons can become highly effective disease models. This article is part of a Special Issue entitled SI: Exploiting human neurons.
Chhetri and colleagues (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202112073) show that Rab11-mediated endosomal recycling regulates cell surface expression of McLeod syndrome protein XK. Mutant ...huntingtin interferes with the recycling of XK to the cell surface and significantly reduces manganese transport across cell membrane.
Efficient release of promoter-proximally paused RNA Pol II into productive elongation is essential for gene expression. Recently, we reported that the Integrator complex can bind paused RNA Pol II ...and drive premature transcription termination, potently attenuating the activity of target genes. Premature termination requires RNA cleavage by the endonuclease subunit of Integrator, but the roles of other Integrator subunits in gene regulation have yet to be elucidated. Here we report that Integrator subunit 8 (IntS8) is critical for transcription repression and required for association with protein phosphatase 2A (PP2A). We find that Integrator-bound PP2A dephosphorylates the RNA Pol II C-terminal domain and Spt5, preventing the transition to productive elongation. Thus, blocking PP2A association with Integrator stimulates pause release and gene activity. These results reveal a second catalytic function associated with Integrator-mediated transcription termination and indicate that control of productive elongation involves active competition between transcriptional kinases and phosphatases.
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•A short motif in IntS8 mediates association with protein phosphatase 2A (PP2A)•Recruitment of PP2A is necessary for Integrator-mediated gene repression•Integrator-bound PP2A dephosphorylates residues within the RNA Pol II CTD and Spt5•PP2A antagonizes transcriptional kinases to prevent productive elongation
The Integrator complex binds promoter-proximally paused RNA Pol II and drives premature transcription termination. Huang et al. identified a motif within Integrator subunit 8 (INTS8) that recruits protein phosphatase 2A (PP2A) to RNA Pol II. Integrator-PP2A then dephosphorylates residues within Spt5 and the RNA Pol II CTD to inhibit pause release and facilitate termination.
A hallmark of severe COVID-19 pneumonia is SARS-CoV-2 infection of the facultative progenitors of lung alveoli, the alveolar epithelial type 2 cells (AT2s). However, inability to access these cells ...from patients, particularly at early stages of disease, limits an understanding of disease inception. Here, we present an in vitro human model that simulates the initial apical infection of alveolar epithelium with SARS-CoV-2 by using induced pluripotent stem cell-derived AT2s that have been adapted to air-liquid interface culture. We find a rapid transcriptomic change in infected cells, characterized by a shift to an inflammatory phenotype with upregulation of NF-κB signaling and loss of the mature alveolar program. Drug testing confirms the efficacy of remdesivir as well as TMPRSS2 protease inhibition, validating a putative mechanism used for viral entry in alveolar cells. Our model system reveals cell-intrinsic responses of a key lung target cell to SARS-CoV-2 infection and should facilitate drug development.
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•iPSC-derived alveolar type 2 cells (iAT2s) are permissive to SARS-CoV-2 infection•SARS-CoV-2 induces an iAT2-intrinsic cytotoxicity and inflammatory response•iAT2s effectively model antiviral drug response and may be used for further drug development
Huang et al. show that human iPSC-derived alveolar type 2 cells (iAT2s) can be used to model COVID-19. They find that iAT2s in air-liquid interface culture are permissive to SARS-CoV-2 infection and show that SARS-CoV-2 induces a rapid inflammatory phenotype predominated by NF-κB signaling.
The Central Apennines in Italy have had multiple moderate‐size but damaging shallow earthquakes. In this study, we optimize the fault geometry and invert for fault slip based on coseismic GPS and ...interferometric synthetic aperture radar (InSAR) for the 2016 Mw 6.2 Amatrice earthquake in Italy. Our results show that nearly all the fault slip occurred between 3 and 6 km depth but extends 20 km along strike. There was less than 4 cm static surface displacement at the town Amatrice where the most devastating damage occurred. Landslides triggered by earthquake ground shaking are not uncommon, but triggered landslides with submeter movement are challenging to be observed in the field. We find evidence of coseismically triggered deep‐seated landslides northwest and northeast of the epicenter where coseismic peak ground acceleration was estimated >0.5 g. By combining ascending and descending InSAR data, we are able to estimate the landslide thickness as at least 100 and 80 m near Monte Vettore and west of Castelluccio, respectively. The landslide near Monte Vettore terminates on the preexisting fault Monte Vettore Fault (MVEF) scarp. Our results imply that the long‐term fault slip rate of MVEF estimated based on paleoseismic studies could potentially have errors due to triggered landslides from nearby earthquake events.
Key Points
InSAR can provide coseismic displacement or other hazard response typically within a few days
Nearly all of the slip occurred between 3 and 5 km in depth but extends about 20 km along strike
The triggered landslide on the Monte Vettore fault may contribute additional fault offset and influence the long‐term fault slip rate
Defects in DNA repair have been extensively linked to neurodegenerative diseases, but the exact mechanisms remain poorly understood. We found that FUS, an RNA/DNA-binding protein that has been linked ...to amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration, is important for the DNA damage response (DDR). The function of FUS in DDR involved a direct interaction with histone deacetylase 1 (HDAC1), and the recruitment of FUS to double-stranded break sites was important for proper DDR signaling. Notably, FUS proteins carrying familial ALS mutations were defective in DDR and DNA repair and showed a diminished interaction with HDAC1. Moreover, we observed increased DNA damage in human ALS patients harboring FUS mutations. Our findings suggest that an impaired DDR and DNA repair may contribute to the pathogenesis of neurodegenerative diseases linked to FUS mutations.
Purpose The prevalence and features of treatment-emergent small-cell neuroendocrine prostate cancer (t-SCNC) are not well characterized in the era of modern androgen receptor (AR)-targeting therapy. ...We sought to characterize the clinical and genomic features of t-SCNC in a multi-institutional prospective study. Methods Patients with progressive, metastatic castration-resistant prostate cancer (mCRPC) underwent metastatic tumor biopsy and were followed for survival. Metastatic biopsy specimens underwent independent, blinded pathology review along with RNA/DNA sequencing. Results A total of 202 consecutive patients were enrolled. One hundred forty-eight (73%) had prior disease progression on abiraterone and/or enzalutamide. The biopsy evaluable rate was 79%. The overall incidence of t-SCNC detection was 17%. AR amplification and protein expression were present in 67% and 75%, respectively, of t-SCNC biopsy specimens. t-SCNC was detected at similar proportions in bone, node, and visceral organ biopsy specimens. Genomic alterations in the DNA repair pathway were nearly mutually exclusive with t-SCNC differentiation ( P = .035). Detection of t-SCNC was associated with shortened overall survival among patients with prior AR-targeting therapy for mCRPC (hazard ratio, 2.02; 95% CI, 1.07 to 3.82). Unsupervised hierarchical clustering of the transcriptome identified a small-cell-like cluster that further enriched for adverse survival outcomes (hazard ratio, 3.00; 95% CI, 1.25 to 7.19). A t-SCNC transcriptional signature was developed and validated in multiple external data sets with > 90% accuracy. Multiple transcriptional regulators of t-SCNC were identified, including the pancreatic neuroendocrine marker PDX1. Conclusion t-SCNC is present in nearly one fifth of patients with mCRPC and is associated with shortened survival. The near-mutual exclusivity with DNA repair alterations suggests t-SCNC may be a distinct subset of mCRPC. Transcriptional profiling facilitates the identification of t-SCNC and novel therapeutic targets.
Objective
To characterize in vivo signatures of pathological diagnosis in a large cohort of patients with primary progressive aphasia (PPA) variants defined by current diagnostic classification.
...Methods
Extensive clinical, cognitive, neuroimaging, and neuropathological data were collected from 69 patients with sporadic PPA, divided into 29 semantic (svPPA), 25 nonfluent (nfvPPA), 11 logopenic (lvPPA), and 4 mixed PPA. Patterns of gray matter (GM) and white matter (WM) atrophy at presentation were assessed and tested as predictors of pathological diagnosis using support vector machine (SVM) algorithms.
Results
A clinical diagnosis of PPA was associated with frontotemporal lobar degeneration (FTLD) with transactive response DNA‐binding protein (TDP) inclusions in 40.5%, FTLD‐tau in 40.5%, and Alzheimer disease (AD) pathology in 19% of cases. Each variant was associated with 1 typical pathology; 24 of 29 (83%) svPPA showed FTLD‐TDP type C, 22 of 25 (88%) nfvPPA showed FTLD‐tau, and all 11 lvPPA had AD. Within FTLD‐tau, 4R‐tau pathology was commonly associated with nfvPPA, whereas Pick disease was observed in a minority of subjects across all variants except for lvPPA. Compared with pathologically typical cases, svPPA‐tau showed significant extrapyramidal signs, greater executive impairment, and severe striatal and frontal GM and WM atrophy. nfvPPA‐TDP patients lacked general motor symptoms or significant WM atrophy. Combining GM and WM volumes, SVM analysis showed 92.7% accuracy to distinguish FTLD‐tau and FTLD‐TDP pathologies across variants.
Interpretation
Each PPA clinical variant is associated with a typical and most frequent cognitive, neuroimaging, and neuropathological profile. Specific clinical and early anatomical features may suggest rare and atypical pathological diagnosis in vivo. Ann Neurol 2017;81:430–443
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