47 48 Lineage-specific epigenomic changes during human corticogenesis have previously 49 remained elusive due to challenges with tissue heterogeneity and sample availability. 50 Here, we analyze cis-regulatory chromatin interactions, open chromatin regions, and 51 transcriptomes for radial glia, intermediate progenitor cells, excitatory neurons, and 52interneurons isolated from mid-gestational human brain samples. We show that 53 chromatin looping underlies transcriptional regulation for lineage-specific genes, with 54 transcription factor motifs, families of transposable elements, and disease-associated 55 variants enriched at distal interacting regions in a cell type-specific manner. A subset of 56 promoters exhibit unusually high degrees of chromatin interactivity, which we term super 57 interactive promoters. Super interactive promoters are enriched for critical lineage-58 specific genes, suggesting that interactions at these loci contribute to the fine-tuning of 59 cell type-specific transcription. Finally, we present CRISPRview, a novel approach for 60 validating distal interacting regions in primary cells. Our study presents the first 61 characterization of cell type-specific 3D epigenomic landscapes during human 62 corticogenesis, advancing our understanding of gene regulation and lineage specification 63 during human brain development. 64 65 Introduction 66 67The human cortex is a complex, heterogeneous structure that undergoes extensive 68 expansion during development, a process which is markedly different and features 69 distinct cell types from mouse cortical development. Previous studies utilized single cell 70 RNA sequencing (scRNA-seq) to unravel the transcriptomic diversity of the developing 71 cortex, revealing at least nine major cell types and up to 26 distinct subtypes in the dorsal 72 cortex alone 1,2 . Much of this diversity arises from cortical stem cells known as radial glia 73 (RG), whose cell bodies reside in the germinal zones (GZs) of the dorsal and ventral 74 cortex. In the dorsal cortex, RG divide asymmetrically to give rise to intermediate 75 progenitor cells (IPCs), which proliferate and differentiate into excitatory neurons (eNs) 3,4 . 76These newborn neurons undergo radial migration until they reach the cortical plate (CP), 77where they mature and undergo synaptogenesis 5 . Meanwhile, interneurons (iNs) 78 produced in the ventral cortex migrate tangentially into the dorsal cortex through the 79 marginal and germinal zones 6 . These processes result in a CP consisting primarily of eNs 80 and iNs and a GZ where all four cell types are intermixed. 81
82Dynamic changes in the epigenomic landscape have been shown to play a critical role in 83 development and cell fate commitment, for instance through the rewiring of physical 84 chromatin loops between promoters and distal regulatory elements 7 . These regulatory 85interactions are of particular interest as their dysregulation has been linked to complex 86 diseases and traits 8,9 . Despite their utility, detailed epigenomic character...