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Biology subjects

Zuckermann, M.

Publications and source records attributed to Zuckermann, M..

6 recordsLinked to original sources

Conserved cerebellar rhombic lip compartmentalization and Eomes regulatory networks govern unipolar brush cell development

The rhombic lip (RL) gives rise to all cerebellar glutamatergic cell types, including unipolar brush cells (UBCs). Disruptions to UBC development can lead to the neurodevelopmental disorder Dandy-Walker Syndrome and the pediatric brain tumor medulloblastoma, but these diseases have not been adequately modeled in mice. To evaluate conservation of UBC development in mouse and human, we examined UBC localization, lineage decisions, and the underlying molecular mechanisms of UBC differentiation using multiplex immunofluorescence and single-cell RNA-seq of wild-type and conditional knockout animals of the primary UBC transcription factor Eomes. Similar to the human RL, the murine RL is molecularly compartmentalized, cycling EOMES+ UBC progenitors are highly abundant, and persist after birth. Eomes regulates the transcriptional networks important for UBC differentiation and migration, but not UBC fate. Overall, our findings suggest that murine UBC development recapitulates many features of human UBC development, with EOMES playing a central role in UBC maturation.

developmental biology↗

Developmental determinants of male bias in medulloblastoma

Boys experience an overall increased incidence of several childhood cancers, including medulloblastoma, a clinically heterogeneous cerebellar tumor. In subtypes of Group 3 and Group 4 medulloblastoma, males are three times more prevalent than females. As medulloblastoma is suspected to initiate during fetal development, we hypothesized that this sex bias reflects a combination of prenatal, sex-specific developmental processes and somatic alterations. To test these hypotheses, we compiled a large multi-omics dataset from children with medulloblastoma, which revealed sex-specific alterations, including frequent loss of the inactive X chromosome in females with Group 4. Generation of a sex-matched single-cell transcriptome atlas of the developing murine cerebellum enabled investigation of putative developmental factors underlying sex bias. Progenitors giving rise to Group 3/4 subgroups were more abundant, more proliferative, and harbored more open chromatin for recruitment of LMX1A and OTX2, master transcription factors defining Group 3/4 identity. Advanced genetically engineered mouse models and human cerebellar organoids were leveraged to determine whether sexual dimorphism arises from intrinsic or extrinsic factors. These models showed that the XY genotype contributed to the phenotype, but the predominant effect was driven by presence of the male gonadal hormone testosterone. Our findings provide a sex-specific genetic and neurodevelopmental explanation for male bias in an aggressive pediatric brain tumor. Outcomes from this study may inform novel treatment strategies delivered according to sex and are likely to be broadly applicable to other sex-biased malignancies arising in early life. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/714163v1_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@566e41org.highwire.dtl.DTLVardef@607ae9org.highwire.dtl.DTLVardef@25679aorg.highwire.dtl.DTLVardef@1b4beec_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

Functionally distinct ALK and ROS1 fusions detected in infant-type hemispheric gliomas converge on STAT3 and SHP2 activation

ALK and ROS1 fusions are emerging as key drivers of infant-type hemispheric gliomas (IHG). With diverse gene partners, the impact of ALK and ROS1 oncoprotein heterogeneity on glioma biology remains unknown. We developed an integrative phospho-proteomic and transcriptomic approach to discover biological functions regulated by five IHG-associated fusions: CCDC88A::ALK, PPP1CB::ALK, GOPC::ROS1, CLIP1::ROS1 and KIF21A::ROS1. Here, we report fusion-specific oncogenic functions conferred by the 5 gene partner, including increased cell motility driven by microtubule-interacting fusions CCDC88A::ALK and CLIP1::ROS1. All studied fusions converged on a non-canonical STAT3 activation. Using affinity purification mass spectrometry, we identify SHP2 in direct interaction with all three ROS1 oncoproteins, but with none of the ALK oncoproteins, which in turn interact with SHC1/SHC3. ROS1 fusions phosphorylated SHP2 to a larger extent than ALK fusions, and analyses of downstream pathways suggested MAPK-independent, non-canonical SHP2-driven functions. Our findings reveal both common and fusion-specific dependencies, offering opportunities to optimize therapeutic strategies for pediatric gliomas.

cancer biology↗

Loss of the Familial Dysautonomia gene Elp1 in cerebellar granule cell progenitors leads to ataxia in mice

Familial Dysautonomia (FD) is an autosomal recessive disorder caused by a splice site mutation in the gene ELP1, which disproportionally affects neurons. While classically characterized by deficits in sensory and autonomic neurons, neuronal defects in the central nervous system have been described. ELP1 is highly expressed in the normal developing and adult cerebellum, but its role in cerebellum development is unknown. To investigate the cerebellar function of Elp1, we knocked out Elp1 in cerebellar granule cell progenitors (GCPs) and examined the outcome on animal behavior and cellular composition. We found that GCP-specific conditional knockout of Elp1 (Elp1cKO) resulted in ataxia by 8 weeks of age. Cellular characterization showed that the animals had smaller cerebella with fewer granule cells. This defect was already apparent 7 days after birth, when Elp1cKO animals also exhibited fewer mitotic GCPs and shorter Purkinje dendrites. Through molecular characterization, we found that loss of Elp1 was associated with an increase in apoptotic cell death and cell stress pathways in GCPs. Our study demonstrates the importance of ELP1 within the developing cerebellum, and suggests that Elp1 loss in the GC lineage may also play a role in the progressive ataxia phenotypes of FD patients.

neuroscience↗

Mapping pediatric brain tumors to their origins in the developing cerebellum

Understanding the cellular origins of childhood brain tumors is key for discovering novel tumor-specific therapeutic targets. Previous strategies mapping cellular origins typically involved comparing human tumors to murine embryonal tissues1,2, a potentially imperfect approach due to spatio-temporal gene expression differences between species3. Here we use an unprecedented single-nucleus atlas of the developing human cerebellum (Sepp, Leiss, et al) and extensive bulk and single-cell transcriptome tumor data to map their cellular origins with focus on three most common pediatric brain tumors - pilocytic astrocytoma, ependymoma, and medulloblastoma. Using custom bioinformatics approaches, we postulate the astroglial and glial lineages as the origins for posterior fossa ependymomas and radiation-induced gliomas (secondary tumors after medulloblastoma treatment), respectively. Moreover, we confirm that SHH, Group3 and Group4 medulloblastomas stem from granule cell/unipolar brush cell lineages, whereas we propose pilocytic astrocytoma to originate from the oligodendrocyte lineage. We also identify genes shared between the cerebellar lineage of origin and corresponding tumors, and genes that are tumor specific; both gene sets represent promising therapeutic targets. As a common feature among most cerebellar tumors, we observed compositional heterogeneity in terms of similarity to normal cells, suggesting that tumors arise from or differentiate into multiple points along the cerebellar "lineage of origin".

cancer biology↗

Establishment of a simplified preparation method for single-nucleus RNA-sequencing and its application to long-term frozen tumor tissues

Recent advances allowing the genomic analysis of individual cells from a bulk population have provided intriguing new insights into areas such as developmental processes and tumor heterogeneity. Most approaches to date, however, rely on the availability of fresh surgical specimens, thereby dramatically reducing the ability to profile particularly rare tissue types. Pediatric central nervous system tumors - the leading cause of childhood cancer deaths - represent one such example, where often only frozen rather than native material is available. Due to an increasing need for advanced techniques to understand the heterogeneity of these tumors, we optimized a method to isolate intact nuclei from long-term frozen pediatric glioma tissues. We performed a technical comparison between different single nucleus RNA-sequencing (snRNA-seq) systems using a patient-derived xenograft model as a test sample. Further, we applied the established nucleus isolation method to analyze frozen primary tissue from two pediatric central nervous system tumors - one pilocytic astrocytoma and one glioblastoma - allowing the identification of distinct tumor cell populations and infiltrating microglia. The results show that our fast, simple and low-cost nuclear isolation protocol provides intact nuclei, which can be used in both droplet-based 3 transcriptome amplification (10X Genomics) and plate-based whole transcriptome amplification (Fluidigm C1) single-cell sequencing platforms, thereby dramatically increasing the potential for application of such methods to rare entities.

cancer biology↗