Biology subjects

Martinez, A.-M.

Publications and source records attributed to Martinez, A.-M..

3 recordsLinked to original sources

bioRxiv2026

A comprehensive HA-tagged PRC1 toolkit enables standardized chromatin profiling and proteomic analysis in Drosophila melanogaster

Polycomb group (PcG) proteins are evolutionarily conserved epigenetic regulators that maintain transcriptional states during development and are frequently misregulated in disease. Here, we generated a comprehensive collection of endogenously HA-tagged alleles for the core components of Polycomb Repressive Complex 1 (PRC1) and additional chromatin regulators in Drosophila melanogaster using CRISPR/Cas9-mediated genome engineering. We show that endogenous HA tagging preserves protein expression, chromatin localization, and genome-wide binding profiles, enabling direct comparison using a common antibody to analyze distinct PcG subunits. Proteomic analyses recovered known components of canonical and non-canonical PRC1 and PRC2 complexes and identified additional PcG-associated factors. Notably, multiple components of the nuclear pore complex (NPC) were detected as PcG interactors, and genetic analyses confirmed a functional interaction between them. This resource provides a platform for standardized analysis of Polycomb function and chromatin regulation that can easily be extended to other chromatin regulatory complexes and applied across different developmental stages. Article SummaryPolycomb group (PcG) proteins are essential regulators of development and genome function. Comparative studies of individual PcG components are often limited by the availability and quality of specific antibodies. Here, we generated a collection of Drosophila melanogaster lines carrying endogenous HA epitope tags in core components of the canonical Polycomb Repressive Complex 1 (PRC1), along with additional chromatin regulators. These tagged proteins faithfully reproduce native chromatin binding and can be used for chromatin mapping and protein interaction studies using a single, highly specific antibody. This standardized resource provides a practical tool for investigating PcG function and chromatin regulation in vivo.

molecular biology↗

bioRxiv2025

A tumor-suppressive role of the PRC1 Polycomb epigenetic complex in the maintenance of adult Drosophila intestinal stem cell identity

Chromatin modulators, like Polycomb group proteins, are key epigenetic regulators of gene expression and are frequently mutated in cancers. In adult stem cells, epigenetic regulation maintains their identity and controls their differentiation during homeostasis or aging, but its direct role in tumorigenesis remains unclear. Here we developed a novel tumor model in Drosophila by exploring the function of Polycomb Repressive Complex 1 (PRC1) in adult intestinal stem cells (ISCs). Disrupting core PRC1 components in ISCs induces the formation of small cell clusters devoid of intestinal markers, a novel phenotype linked to premature mortality under stress. These clusters exhibit neoplastic characteristics such as overproliferation and continuous growth in serial transplantations, leading to their designation as tumor-initiating intestinal cells (TIICs). While JAK/STAT signaling contributes to TIIC growth, the NF-{kappa}B-related Toll/Imd immune pathways restrict their expansion independently of cell death. Altogether, our results highlight PRC1 as an epigenetic tumor suppressor in adult stem cells. AUTHOR SUMMARYOur research explores how stem cells in the adult intestine stay healthy and avoid becoming cancerous. We focused on a group of proteins called Polycomb Repressive Complex 1 (PRC1), which help regulate which genes are turned off in a cell. While these proteins are known to play important roles during development and cancer prevention, their function in the adult intestine has been less clear. Using the fruit fly Drosophila, we discovered that when PRC1 function is lost in intestinal stem cells, abnormal clusters of cells begin to form. These clusters grow uncontrollably, lose their normal identity, and can keep growing when transplanted--traits that are typical of cancer. Interestingly, we also found that parts of the immune system, specifically NF-{kappa}B-related pathways, can act inside these tumor cells to limit their growth--revealing a protective role that hasnt been seen before in the adult gut. This work provides new insights into how epigenetic regulation and immune signaling work together to keep stem cells from turning cancerous. It opens up new possibilities for understanding how cancers begin and how the body may naturally resist them, even at the level of the tissue.

cancer biology↗

bioRxiv2023

Transient loss of Polycomb components induces an epigenetic cancer fate

Cell fate depends on genetic, epigenetic and environmental inputs that are interconnected, making it difficult to disentangle their respective contributions to cell fate decisions1-3, and epigenetic reprogramming is a major contributor to tumor plasticity and adaptation4-6. Although cancer initiation and progression are generally associated with the accumulation of somatic mutations7,8, substantial epigenomic alterations underlie many aspects of tumorigenesis and cancer susceptibility9-18, suggesting that genetic mechanisms alone may not be sufficient to drive malignant transformations19-23. However, whether purely non-genetic reprogramming mechanisms are sufficient to initiate tumorigenesis irrespective of mutations is unknown. Here, we show that a transient perturbation of transcriptional silencing mediated by Polycomb-Group proteins is sufficient to induce an irreversible switch to a cancer cell fate in Drosophila. This is linked to the irreversible derepression of genes that can drive tumorigenesis, including JNK and JAK-STAT signalling pathways and zfh1, the fly homolog of the ZEB1 oncogene, which we show to be a necessary driver of the cancer fate. These data show that a reversible perturbation of Polycomb-Group protein levels can induce cancer in the absence of driver mutations and suggest that this is achieved through epigenetic inheritance of altered cell fates.

developmental biology↗