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SUMMARYUnderstanding how human gene expression is coordinately regulated by functional units of proteins across the genome remains a major biological goal. Here, we present COMET, a high-throughput screening platform for combinatorial effector targeting for the identification of transcriptional modulators. We generate libraries of combinatorial dCas9-based fusion proteins, containing two to six effector domains, allowing us to systematically investigate more than 110,000 combinations of effector proteins at endogenous human loci for their influence on transcription. Importantly, we keep full proteins or domains intact, maintaining catalytic cores and surfaces for protein-protein interactions. We observe more than 5800 significant hits that modulate transcription, we demonstrate cell type specific transcriptional modulation, and we further investigate epistatic relationships between our effector combinations. We validate unexpected combinations as synergistic or buffering, emphasizing COMET as both a method for transcriptional effector discovery, and as a functional genomics tool for identifying novel domain interactions and directing locus-specific biochemistry.

Ribosome profiling, which is based on deep sequencing of ribosome footprints, has served as a powerful tool for elucidating the regulatory mechanism of protein synthesis. However, the current method has substantial issues: contamination by rRNAs and the lack of appropriate methods to measure ribosome numbers in transcripts. Here, we overcome these hurdles through the development of “Ribo-FilterOut”, which is based on the separation of footprints from ribosome subunits by ultrafiltration, and “Ribo-Calibration”, which relies on external spike-ins of stoichiometrically defined mRNA-ribosome complexes. A combination of these approaches estimates the number of ribosomes on a transcript, the translation initiation rate, and the overall number of translation events before its decay, all in a genome-wide manner. Moreover, our method reveals the allocation of ribosomes under heat shock stress, during aging, and across cell types. Our strategy of modified ribosome profiling measures kinetic and stoichiometric parameters of cellular translation across the transcriptome. Ribosome profiling faces issues with rRNA contamination and measurements of ribosome numbers on transcripts. Here, the authors develop Ribo-FilterOut and Ribo-Calibration, methods which can be used to estimate kinetic and stoichiometric parameters of translation under various conditions.

BackgroundCHD7 encodes an ATP-dependent chromodomain helicase DNA binding protein; mutations in this gene lead to multiple developmental disorders, including CHARGE (Coloboma, Heart defects, Atresia of the choanae, Retardation of growth and development, Genital hypoplasia, and Ear anomalies) syndrome. How the mutations cause multiple defects remains largely unclear. Embryonic definitive endoderm (DE) generates the epithelial compartment of vital organs such as the thymus, liver, pancreas, and intestine.MethodsIn this study, we used the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technique to delete the CHD7 gene in human embryonic stem cells (hESCs) to generate CHD7 homozygous mutant (CHD7?/?), heterozygous mutant (CHD7+/?), and control wild-type (CHD7+/+) cells. We then investigated the ability of the hESCs to develop into DE and the other two germ layers, mesoderm and ectoderm in vitro. We also compared global gene expression and chromatin accessibility among the hESC-DE cells by RNA sequencing (RNA-seq) and the assay for transposase-accessible chromatin with sequencing (ATAC-seq).ResultsWe found that deletion of CHD7 led to reduced capacity to develop into DE and mesoderm in a dose-dependent manner. Loss of CHD7 led to significant changes in the expression and chromatin accessibility of genes associated with several pathways. We identified 40 genes that were highly down-regulated in both the expression and chromatin accessibility in CHD7 deleted hESC-DE cells.ConclusionsCHD7 is critical for DE and mesodermal development from hESCs. Our results provide new insights into the mechanisms by which CHD7 mutations cause multiple congenital anomalies.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13287-025-04437-9.

The spatial organization of molecules in a cell is essential for their functions. While current methods focus on discerning tissue architecture, cell–cell interactions, and spatial expression patterns, they are limited to the multicellular scale. We present Bento, a Python toolkit that takes advantage of single-molecule information to enable spatial analysis at the subcellular scale. Bento ingests molecular coordinates and segmentation boundaries to perform three analyses: defining subcellular domains, annotating localization patterns, and quantifying gene–gene colocalization. We demonstrate MERFISH, seqFISH + , Molecular Cartography, and Xenium datasets. Bento is part of the open-source Scverse ecosystem, enabling integration with other single-cell analysis tools.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13059-024-03217-7.

Huntington’s disease and other disorders of the basal ganglia create challenges for biomolecule-based medicines given the poor accessibility of these deep brain structures following intracerebral or intravascular delivery. Here, we found that low dose, low volume delivery of unbiased AAV libraries into the globus pallidus allowed recovery of novel capsids capable of broad access to key deep brain and cortical structures relevant for human therapies. One such capsid, AAV-DB-3, provided transduction of up to 45% of medium spiny neurons in the adult NHP striatum, along with substantial transduction of relevant deep layer neurons in the cortex. Notably, AAV-DB-3 behaved similarly in mice as in NHPs and potently transduced human neurons derived from induced pluripotent stem cells. Thus, AAV-DB-3 provides a unique AAV for network level brain gene therapies that translates up and down the evolutionary scale for preclinical studies and eventual clinical use. To date, brain gene therapies require high vector doses. Here, authors devised an AAV capsid screen and found variants with unprecedented potency for transduction of deep brain and cortical neurons and human iPSC-neurons with cell tropism relevant for Huntington’s and Parkinson’s disease.