PT  - JOURNAL ARTICLE
AU  - Havva Ortabozkoyun-Kara
AU  - Pin-Yao Huang
AU  - Hyunwoo Cho
AU  - Varun Narendra
AU  - Gary Leroy
AU  - Jane A. Skok
AU  - Aristotelis Tsirigos
AU  - Esteban O. Mazzoni
AU  - Danny Reinberg
TI  - A CRISPR Screen Identifies Myc-associated Zinc Finger Protein (MAZ) as an Insulator Functioning at CTCF boundaries in <em>Hox</em> Clusters
AID  - 10.1101/2020.08.25.267237
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.08.25.267237
4099  - http://biorxiv.org/content/early/2020/08/26/2020.08.25.267237.short
4100  - http://biorxiv.org/content/early/2020/08/26/2020.08.25.267237.full
AB  - The essential CCCTC-binding factor (CTCF) is critical to three-dimensional (3D) genome organization. CTCF binding insulates active and repressed genes within the Hox clusters upon differentiation, but such binding does not participate in boundary formation in all cell types, such as embryonic stem cells. We conducted a genome-wide CRISPR knockout screen to identify genes required for CTCF boundary activity at the HoxA cluster, complemented by novel biochemical approaches. This screen identified Myc-associated zinc finger protein (MAZ) as a CTCF insulator co-factor, among other candidates listed herein. MAZ depletion or specific deletion of MAZ motifs within the Hox clusters led to de-repression of posterior Hox genes immediately after CTCF boundaries upon differentiation, which phenocopied deletion of the proximal CTCF motifs. Similar to CTCF, MAZ interacted with the cohesin subunit, RAD21. Upon loss of MAZ, local contacts within topologically associated domains (TADs) were disrupted, as evidenced by HiC analysis. Thus, MAZ is a novel factor sharing insulation properties with CTCF and contributing to the genomic architectural organization.One Sentence Summary MAZ is identified as an insulator functioning at CTCF boundaries delimiting active and repressed genes at Hox clustersCompeting Interest StatementD.R. was a cofounder of Constellation Pharmaceuticals and Fulcrum Therapeutics. Currently, D.R has no affiliation with either company. The authors declare that they have no other competing interests.