Biology subjects

Charlton, J.

Publications and source records attributed to Charlton, J..

3 recordsLinked to original sources

bioRxiv2025

Tumour suppressor WT1 and its interacting protein RNA helicase DDX5 regulate the microRNA let7/Igf1r axis in the kidney mesenchyme

Germline mutations in tumour suppressor, Wilms Tumour 1 (WT1) as well as somatic and germline mutations in microRNA processing genes (MIRPG) have been identified in Wilms Tumours (WT), where upregulation of IGF2 through genetic and/or epigenetic mechanisms is commonly seen. Whether these different epigenetic and genetic causes converge on common targets is still unclear. WT1 is also involved in RNA binding and regulates the stability of these developmental mRNAs. We now show that WT1 interacts with microRNA let-7 and proteins involved in microRNA processing wherein DDX5 is found to be an important regulator. WT1 absence results in decreased microRNA levels in cell lines and kidney mesenchyme, which is further downregulated in a WT1 and DDX5 double knockdown, ultimately modulating Igf1r expression. These findings suggest a plausible mechanism by which WT1 mutations lead to WT, and converge on microRNA pathway and IGF signalling pathway, which are important contributing factors in the aetiology of WT.

cancer biology↗

bioRxiv2019

Tumour suppressor WT1 regulates the let-7-Igf1r axis in kidney mesenchyme

Wilms tumour 1 (WT1) is a transcription factor and a tumour suppressor, essential for the development and homeostasis of multiple tissues derived from the intermediate and lateral plate mesoderm. Germline WT1 mutations result in the eponymous paediatric kidney cancer, genitourinary anomalies and in some cases congenital diaphragmatic hernia One common feature in Wilms Tumours (WT), is upregulation of IGF2 through genetic and/or epigenetic mechanisms. Recent studies have identified both somatic and germline mutations in microRNA processing genes (MIRPG) in WT. Whether these different epigenetic and genetic causes converge on common targets and the mechanisms by which they act are still unclear. WT1 is involved in RNA binding and regulates the RNA stability of important developmental genes. We now show that WT1 interacts with let-7 family of microRNAs, and the absence of WT1 results in reduced levels of mature microRNA in cell lines and kidney mesenchyme. As a consequence, let-7 targets, including Igf1 receptor (Igf1r), are upregulated in the absence of Wt1, thus confirming the presence of a WT1-let7-Igf1r axis. These findings suggest a possible mechanism by which WT1 mutations lead to WT, and reinforce the idea that the perturbation of the microRNA and IGF signalling pathways are important contributing factors in the aetiology of WT.

cancer biology↗

bioRxiv2019

Dissecting mechanisms of human islet differentiation and maturation through epigenome profiling

Investigating pancreatic islet differentiation from human stem cells in vitro provides a unique opportunity to dissect mechanisms that operate during human development in utero. We developed methods to profile DNA methylation, chromatin accessibility, and histone modifications from pluripotent stem cells to mature pancreatic islet cells, uncovering widespread epigenome remodeling upon endocrine commitment. Key lineage-defining loci are epigenetically primed before activation, foreshadowing cell fate commitment, and we show that priming of -cell-specific enhancers steers polyhormonal cells toward an -cell fate. We further dissect pioneer factors and core regulatory circuits across islet cell differentiation and maturation stages, which identify LMX1B as a key regulator of in vitro-derived endocrine progenitors. Finally, by contrasting maturing stem cell-derived to natural {beta}-cells, we discover that circadian metabolic cycles trigger rhythmic control of insulin synthesis and release and promote mature insulin responsiveness via an increased glucose threshold. These findings form a basis for understanding mechanisms orchestrating human islet cell specification and maturation.

genomics↗