A hPSC-based platform to discover gene-environment interactions that impact human ß-cell and dopamine neuron survival.

Common disorders, including diabetes and Parkinson's disease, are caused by a combination of environmental factors and genetic susceptibility. However, defining the mechanisms underlying gene-environment interactions has been challenging due to the lack of a suitable experimental platform. Using pancreatic ß-like cells derived from human pluripotent stem cells (hPSCs), we discovered that a commonly used pesticide, propargite, induces pancreatic ß-cell death, a pathological hallmark of diabetes. Screening a panel of diverse hPSC-derived cell types we extended this observation to a similar susceptibility in midbrain dopamine neurons, a cell type affected in Parkinson's disease. We assessed gene-environment interactions using isogenic hPSC lines for genetic variants associated with diabetes and Parkinson's disease. We found GSTT1-/- pancreatic ß-like cells and dopamine neurons were both hypersensitive to propargite-induced cell death. Our study identifies an environmental chemical that contributes to human ß-cell and dopamine neuron loss and validates a novel hPSC-based platform for determining gene-environment interactions.

Derivation and characterization of a UCP1 reporter human ES cell line.

Interest in human brown fat as a novel therapeutic target to tackle the growing obesity and diabetes epidemic has increased dramatically in recent years. While much insight into brown fat biology has been gained from murine cell lines and models, few resources are available to study human brown fat in vitro, which makes the need for new ways to derive and study human brown adipocytes imperative. Human ES cell based reporter systems present an excellent tool to identify, mark, and purify cell populations of choice. In this study, we detail the derivation and characterization of a novel human ES UCP1 reporter cell line that marks UCP1 positive adipocytes in vitro. We targeted a mCherry reporter to the UCP1 stop codon via CRISPR-Cas9 based gene targeting. The brown adipocytes derived from reporter cells express UCP1, display high mitochondrial content, multi-locular lipid morphology, and exhibit functional properties such as lipolysis. The mCherry positive cells purified after cell sorting show elevated expression of brown fat marker genes and a high similarity to isolated human brown fat via RNA-seq analysis. Finally, we demonstrate the utility of this reporter to real time monitor UCP1 expression upon stimulation. This reporter cell line thus presents new opportunities to study human brown fat biology by enabling future work to understand early human brown fat development, perform disease modeling, and facilitate drug screening.

An Integrated Systems Biology Approach Identifies TRIM25 as a Key Determinant of Breast Cancer Metastasis.

At the root of most fatal malignancies are aberrantly activated transcriptional networks that drive metastatic dissemination. Although individual metastasis-associated genes have been described, the complex regulatory networks presiding over the initiation and maintenance of metastatic tumors are still poorly understood. There is untapped value in identifying therapeutic targets that broadly govern coordinated transcriptional modules dictating metastatic progression. Here, we reverse engineered and interrogated a breast cancer-specific transcriptional interaction network (interactome) to define transcriptional control structures causally responsible for regulating genetic programs underlying breast cancer metastasis in individual patients. Our analyses confirmed established pro-metastatic transcription factors, and they uncovered TRIM25 as a key regulator of metastasis-related transcriptional programs. Further, in vivo analyses established TRIM25 as a potent regulator of metastatic disease and poor survival outcome. Our findings suggest that identifying and targeting keystone proteins, like TRIM25, can effectively collapse transcriptional hierarchies necessary for metastasis formation, thus representing an innovative cancer intervention strategy.

High-Content Screening in hPSC-Neural Progenitors Identifies Drug Candidates that Inhibit Zika Virus Infection in Fetal-like Organoids and Adult Brain.

Zika virus (ZIKV) infects fetal and adult human brain and is associated with serious neurological complications. To date, no therapeutic treatment is available to treat ZIKV-infected patients. We performed a high-content chemical screen using human pluripotent stem cell-derived cortical neural progenitor cells (hNPCs) and found that hippeastrine hydrobromide (HH) and amodiaquine dihydrochloride dihydrate (AQ) can inhibit ZIKV infection in hNPCs. Further validation showed that HH also rescues ZIKV-induced growth and differentiation defects in hNPCs and human fetal-like forebrain organoids. Finally, HH and AQ inhibit ZIKV infection in adult mouse brain in vivo. Strikingly, HH suppresses viral propagation when administered to adult mice with active ZIKV infection, highlighting its therapeutic potential. Our approach highlights the power of stem cell-based screens and validation in human forebrain organoids and mouse models in identifying drug candidates for treating ZIKV infection and related neurological complications in fetal and adult patients.