Gagne, A. L. | bioRxiv Science

bioRxiv2024

Single-cell transcriptomics reveal synergistic and antagonistic effects of T21 and GATA1s on hematopoiesis

Trisomy 21 (T21), or Down syndrome (DS), is associated with baseline macrocytic erythrocytosis, thrombocytopenia, and neutrophilia, as well as transient abnormal myelopoiesis (TAM) and myeloid leukemia of DS (ML-DS). TAM and ML-DS blasts both arise from an aberrant megakaryocyte-erythroid progenitor and exclusively express GATA1s, the truncated isoform of GATA1, while germline GATA1s mutations in a non-T21 context lead to congenital cytopenia(s) without a leukemic predisposition. This suggests that T21 and GATA1s both perturb hematopoiesis in multipotent progenitors, but studying their individual effects is challenging due to limited access to relevant human progenitor populations. To dissect individual developmental impacts, we used single-cell RNA-sequencing to interrogate hematopoietic progenitor cells (HPCs) from isogenic human induced pluripotent stem cells differing only by chromosome 21 and/or GATA1 status. The transcriptomes of these HPCs revealed significant heterogeneity and lineage skew dictated by T21 and/or GATA1s. T21 and GATA1s each disrupted temporal regulation of lineage-specific transcriptional programs and specifically perturbed cell cycle genes. Trajectory inference revealed that GATA1s nearly eliminated erythropoiesis, slowed MK maturation, and promoted myelopoiesis in the euploid context, while in T21 cells, GATA1s competed with the enhanced erythropoiesis and impaired megakaryopoiesis driven by T21 to promote production of immature erythrocytes, MKs, and myeloid cells. The use of isogenic cells revealed distinct transcriptional programs that can be attributed specifically to T21 and GATA1s, and how they independently and synergistically result in HPC proliferation at the expense of maturation, consistent with a pro-leukemic phenotype.

molecular biology↗

bioRxiv2023

A novel iPSC model reveals selective vulnerability of neurons in Multiple Sulfatase Deficiency

Multiple sulfatase deficiency (MSD) is an ultra-rare, inherited lysosomal storage disease caused by mutations in the gene sulfatase modifying factor 1 (SUMF1). MSD is characterized by the functional deficiency of all sulfatase enzymes, leading to the storage of sulfated substrates including glycosaminoglycans (GAGs), sulfolipids, and steroid sulfates. Patients with MSD experience severe neurological impairment, hearing loss, organomegaly, corneal clouding, cardiac valve disease, dysostosis multiplex, contractures, and ichthyosis. Here, we generated a novel human model of MSD by reprogramming patient peripheral blood mononuclear cells to establish an MSD iPSC line (SUMF1 p.A279V). We also generated an isogenic control iPSC line by correcting the pathogenic variant with CRISPR/Cas9 gene editing. We successfully differentiated these iPSC lines into neural progenitor cells (NPCs) and NGN2-induced neurons (NGN2-iN) to model the neuropathology of MSD. Mature neuronal cells exhibited decreased SUMF1 gene expression, increased lysosomal stress, impaired neurite outgrowth and maturation, reduced sulfatase activities, and GAG accumulation. Interestingly, MSD iPSCs and NPCs did not exhibit as severe of phenotypes, suggesting that as neurons differentiate and mature, they become more vulnerable to loss of SUMF1. In summary, we demonstrate that this human iPSC-derived neuronal model recapitulates the cellular and biochemical features of MSD. These cell models can be used as tools to further elucidate the mechanisms of MSD pathology and for the development of therapeutics.

cell biology↗