Roles of H2A.Z histone variant isoforms during enterocyte-like differentiation process

The histone variant H2A.Z plays important functions in the regulation of gene expression. In mammals, it is encoded by two genes, giving rise to two highly related isoforms named H2A.Z.1 and H2A.Z.2, which can have similar or antagonistic functions depending on the promoter. Knowledge of the physiopathological consequences of such functions emerges, but how the balance between these isoforms regulates tissue homeostasis is not fully understood. Here, we investigated the relative role of H2A.Z isoforms in intestinal epithelial homeostasis. Through genome-wide analysis of H2A.Z genomic localization in differentiating Caco-2 cells, we uncovered an enrichment of H2A.Z isoforms on the bodies of genes which are induced during enterocyte differentiation, stressing the potential importance of H2A.Z isoforms dynamics in this process. Through a combination of in vitro and in vivo experiments, we further demonstrated the two isoforms cooperate for stem and progenitor cells proliferation, as well as for secretory lineage differentiation. However, we found that they antagonistically regulate enterocyte differentiation, with H2A.Z.1 preventing terminal differentiation and H2A.Z.2 favoring it. Altogether, these data indicate that H2A.Z isoforms are critical regulators of intestine homeostasis and may provide a paradigm of how the balance between two isoforms of the same chromatin structural protein can control physiopathological processes. ChIP-seq : Samples were prepared in duplicates from subconfluent (Sc) or 7 days post-confluent (Pc) populations of Caco-2/15 cells expressing flagged version of H2A.Z.1 or H2A.Z.2 isoform. ChIP-seq reads were aligned to hg38 human genome using BWA and processed (sorting, PCR duplicates, minimum quality of 25 and indexing). BigWig were obtained using Deeptools with exactScaling parameters and CPM normalization. Peaks were called uing MACS with the significance cut-off q-value <=0.001 RNA-seq : Samples were prepared in duplicates from subconfluent (Sc) or 7 days post-confluent (Pc) populations of Caco-2/15 cells expressing flagged version of H2A.Z.1 or H2A.Z.2 isoform. The quality of each raw sequencing file (fastq) was checked with FastQC. Stranded paired-end reads were mapped to human rDNA genome and unmapped reads were aligned on hg38 using STAR (v2.5.2b) and processed using samtools keeping only primary alignement. Raw reads count were obtained using HT-seq.