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Pommerenke, C.

Publications and source records attributed to Pommerenke, C..

2 recordsLinked to original sources

iPS-CNM: an iPSC collection generated by base editing for centronuclear myopathy

Centronuclear myopathy (CNM) is a rare form of inherited diseases often caused by single base mutations. Modelling CNM is challenging due to the diversity of CNM mutations and genetic background of individual patient. To address this, we used base editing to introduce CNM mutations into an induced pluripotent stem cell (iPSC) line from a healthy donor, generating a collection of iPSC lines (iPS-CNM) carrying distinct CNM mutations. We found that the efficiency of base editing depended critically on selecting base editor (BE) variants and the target sequences. Optimization using different BE variant and sgRNA pair was required for each target site. Moreover, whole genome sequencing (WGS) was performed to confirm on-targets and detect off-targets in order to select iPSC clones for the collection. Our findings highlight the feasibility of base editing for generating an iPSC collection from one parental iPSC line combined with thorough evaluation of rare off-targets using WGS.

genetics↗

Transcription-driven establishment of DNA methylation at the PWS/AS imprinted region

Genomic imprinting is regulated by allele-specific DNA methylation at imprinting control regions, ensuring parent-of-origin-specific gene expression. The human Prader-Willi/Angelman syndrome (PWS/AS) locus on chromosome 15q harbours a bipartite imprinting center consisting of the PWS-SRO, which acquires maternal-specific methylation, and the AS-SRO, an upstream promoter that initiates transcription in oocytes. To directly test whether transcription across the PWS-SRO is sufficient to trigger de novo DNA methylation, a human iPSC based in vitro system was established in which the endogenous AS-SRO was replaced by a doxycycline-inducible promoter driving transcription across the PWS-SRO. Inducible transcription was robustly activated upon doxycycline treatment and confirmed by splicing to SNRPN exon 2, mirroring the structure of oocyte-derived transcripts. Gain of DNA methylation up to 10% was observed only following directed differentiation into the endodermal lineage. This study provides the first direct evidence in a human model that transcription across the PWS-SRO is necessary but not sufficient for de novo DNA methylation. Instead, differentiation-dependent cues, potentially resembling aspects of the oocyte environment, are required. The established in vitro system enables controlled dissection of the molecular factors and chromatin dynamics underlying imprint establishment at the PWS/AS locus.

genetics↗