Biology subjects

Merkuri, F.

Publications and source records attributed to Merkuri, F..

4 recordsLinked to original sources

bioRxiv2026

Lactate epigenetically shapes tumor cell states in H3K27M diffuse midline gliomas

H3K27M diffuse midline gliomas (DMGs) are lethal and lack treatment options. These tumors exhibit tumor heterogeneity with aggressive oligodendrocyte precursor (OPC)- and mesenchymal (MES)-like cell states. Because all tumor cells bear H3K27M, tumor heterogeneity has been attributed to microenvironmental cues that remain obscure. H3K27M DMGs exhibit increased glycolysis and the Warburg effect to produce lactate. Lactate can directly modify histone lysines including H3K27Lac, and we hypothesized that lactate epigenetically regulates tumor cell states in H3K27M DMGs. We undertook a comprehensive and integrated analysis of H3K27M DMG cell lines, animal models, tumor tissues, and magnetic resonance spectroscopy in patients to decipher the epigenetic roles of lactate. Here, we report that H3K27M cells uniquely exhibit elevation of the activating mark H3K27Lac. We observed significant heterogeneity in lactate levels within tumors, and the addition of exogenous lactate resulted in marked increases in H3K27Lac and the expression of critical OPC- and MES- like gene signature genes, which correlates with poorer patient outcomes. Our therapeutic approach leverages the inhibition of CBP/p300, which deposits both H3K27Lac and H3K27ac. Targeting CBP/p300 effectively reduces both H3K27Lac and H3K27ac levels, suppresses key OPC- and MES-like signatures, and shows efficacy in preclinical models. Collectively, our findings identify lactate as a key player in the epigenetic regulation of tumor cell state heterogeneity and suggest that targeting this pathway offers promise for addressing the heterogeneous complexities of H3K27M DMGs.

molecular biology↗

bioRxiv2024

Etiology of Craniofacial and Cardiac Malformations in a Mouse Model of SF3B4-Related Syndromes

Pathogenic variants in SF3B4 are responsible for the acrofacial disorders Nager and Rodriguez Syndrome, also known as SF3B4-related Syndromes, associated with malformations in the head, face, limbs, vertebrae as well as the heart. To uncover the etiology of craniofacial malformations found in SF3B4-related syndromes, mutant mouse lines with homozygous deletion of Sf3b4 in neural crest cells (NCC) were generated. Like in human patients, these embryos had craniofacial and cardiac malformations with variable expressivity and penetrance. The severity and survival of Sf3b4 NCC mutants was modified by the level of Sf3b4 in neighbouring non NCC. RNA sequencing analysis of heads of embryos prior to morphological abnormalities showed significant changes in expression of genes forming the NCC regulatory network, as well as an increase in exon skipping. We identified several key transcription factors and histone modifiers involved in craniofacial and cardiac development with increased exon skipping. Increased exon skipping was also associated with use of a more proximal branch point, as well as an enrichment in thymidine bases in the 50bp around the branch points. We propose that decrease in Sf3b4 causes changes in the expression and splicing of transcripts required for proper craniofacial and cardiac development, leading to abnormalities.

developmental biology↗

bioRxiv2020

Mis-splicing of Mdm2 leads to increased P53-activity and craniofacial defects in a MFDM Eftud2 mutant mouse model

EFTUD2, a GTPase and core component of the splicesome, is mutated in patients with mandibulofacial dysostosis with microcephaly (MFDM). We generated a mutant mouse line with conditional mutation in Eftud2 and used Wnt1-Cre2 to delete it in neural crest cells. Homozygous deletion of Eftud2 leads to neural crest cell death and malformations in the brain and craniofacial region of embryos. RNAseq analysis of embryonic mutant heads revealed a significant increase in exon skipping, in retained introns and enriched levels of Mdm2 transcripts lacking exon 3. Mutants also had increased nuclear P53, higher expression of P53-target genes, and increased cell death. Their craniofacial development was significantly improved when treated with Pifithrin-, an inihibitor of P53. We propose that craniofacial defects caused by mutations of EFTUD2 are a result of mis-splicing of Mdm2 and P53-associated cell death. Hence, drugs that reduce P53 activity may help prevent craniofacial defects associated with spliceosomopathies.

developmental biology↗

bioRxiv2019

Satb2 regulates proliferation and nuclear integrity of pre-osteoblasts

Special AT-rich sequence binding protein 2 (Satb2) is a matrix attachment region (MAR) binding protein. Satb2 impacts skeletal development by regulating gene transcription required for osteogenic differentiation. Although its role as a high-order transcription factor is well supported, other roles for Satb2 in skeletal development remain unclear. In particular, the impact of dosage sensitivity (heterozygous mutations) and variance on phenotypic severity is still not well understood. To further investigate molecular and cellular mechanisms of Satb2-mediated skeletal defects, we used the CRISPR/Cas9 system to generate Satb2 mutations in MC3T3-E1 cells. Our data suggest that, in addition to its role in differentiation, Satb2 regulates progenitor proliferation. We also find that mutations in Satb2 cause chromatin defects including nuclear blebbing and donut-shaped nuclei. These defects may contribute to a slight increase in apoptosis in mutant cells, but apoptosis is insufficient to explain the proliferation defects. Satb2 expression exhibits population-level variation and is mostly highly expressed from late G1 to late G2. Based on these data, we hypothesize that Satb2 may regulate proliferation through two separate mechanisms. First, Satb2 may regulate the expression of genes necessary for cell cycle progression in pre-osteoblasts. Second, similar to other MAR-binding proteins, Satb2 may participate in DNA replication. Deficiencies in either of these processes could reduce the pace of cell cycle progression and contribute to nuclear damage. We also hypothesize that Satb2-mediated proliferation defects may be buffered in some genetic backgrounds, which provides some explanation for differences in severity of skeletal defects. Further elucidation of the role of Satb2 in proliferation has potential impacts on our understanding of both skeletal defects and cancer.

developmental biology↗