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MED12 is a key regulator of transcription and chromatin architecture, essential for normal hematopoiesis. While its dysregulation has been implicated in hematological malignancies, the mechanisms driving its upregulation in acute myeloid leukemia (AML) remain poorly understood. We investigated MED12 expression across AML subgroups by integrating chromatin accessibility profiling, histone modification landscapes, and DNA methylation (DNAm) patterns. Functional assays using DNMT inhibition were performed to dissect the underlying regulatory mechanisms. MED12 shows subtype-specific upregulation in AML compared to hematopoietic stem and progenitor cells, independent of somatic mutations. Chromatin accessibility profiling reveals that the MED12 locus is epigenetically primed in AML blasts, with increased DNase hypersensitivity at regulatory elements. Histone modification analysis demonstrates strong H3K4me3 and H3K27ac enrichment around the transcription start site (TSS), consistent with promoter activation, while upstream and intragenic regions exhibit enhancer-associated marks (H3K4me1, H3K27ac). Notably, hypermethylation within TSS-proximal regulatory regions (TPRRs)—including promoter-overlapping and adjacent CpG islands—correlates with ectopic MED12 overexpression, challenging the canonical view of DNAm as strictly repressive. Functional studies show that DNMT inhibition via 5-azacytidine reduces MED12 expression despite promoter demethylation in cells with hypermethylated TPRRs, suggesting a noncanonical role for DNA methylation in maintaining active transcription. Furthermore, MED12 expression positively correlates with DNMT3A and DNMT3B expression, implicating these methyltransferases in sustaining its epigenetic activation. This study identifies a novel regulatory axis in which aberrant DNA methylation, rather than genetic mutation, drives MED12 upregulation in AML. Our findings suggest that TPRR hypermethylation may function noncanonically to support transcriptional activation, likely in cooperation with enhancer elements. These results underscore the importance of epigenetic mechanisms in AML and highlight enhancer-linked methylation as a potential contributor to oncogene dysregulation. Future studies should further explore the role of noncanonical methylation-mediated gene activation in AML pathogenesis and therapeutic targeting. The online version contains supplementary material available at 10.1186/s13072-025-00610-9.

Innovative identification technologies for hematopoietic stem cells (HSCs) have expanded the scope of stem cell biology. Clinically, the functional quality of HSCs critically influences the safety and therapeutic efficacy of stem cell therapies. However, most analytical techniques capture only a single snapshot, disregarding the temporal context. A comprehensive understanding of the temporal heterogeneity of HSCs necessitates live-cell, real-time and non-invasive analysis. Here, we developed a prediction system for HSC diversity by integrating single-HSC ex vivo expansion technology with quantitative phase imaging (QPI)-driven machine learning. By analyzing the cellular kinetics of individual HSCs, we discovered previously undetectable diversity that snapshot analysis cannot resolve. The QPI-driven algorithm quantitatively evaluates stemness at the single-cell level and leverages temporal information to significantly improve prediction accuracy. This platform advances the field from snapshot-based identification of HSCs to dynamic, time-resolved prediction of their functional quality based on past cellular kinetics. Subject terms: Haematopoietic stem cells, Stem-cell differentiation, Self-renewal, Imaging

Reticular dysgenesis (RD) is a rare genetic disorder caused by mutations in the adenylate kinase 2 ( AK2 ) gene. It is characterized by a T − B − severe combined immunodeficiency, agranulocytosis, and sensorineural deafness. We established and characterized a haematopoiesis‐specific conditional Ak2 ‐knockout mouse model to provide a model system to study the molecular pathophysiology of RD. As expected from the human phenotype of RD, haematopoiesis‐specific AK2‐deficient embryos had a small, atrophic thymus consisting mainly of epithelial cells. No recognizable T‐cell component was observed, but B‐cell lineage precursor cells were present in the foetal liver. The effects of AK2 deficiency on myelopoiesis were less severe in mice than in humans. The absolute numbers of monocytes, macrophages, granulocytes and megakaryocytes in foetal liver as well as colony‐forming precursors were not reduced. In contrast to humans, haematopoiesis‐specific Ak2 ‐knockout mice exhibit embryonic lethality between E13 and E15 due to severe anaemia caused by an early block in definitive erythropoiesis. Murine erythroid progenitors mainly express AK2 and only low levels of functionally related kinases, which are unable to compensate for AK2 deficiency, in contrast to human erythroid progenitors.

This work focused on generating a three-dimensional (3D) in vitro dynamic model to study chronic lymphocytic leukemia (CLL) cell dissemination, homing, and mechanisms of therapy resistance. We used a gelatin-based, hard porous biomaterial as a support matrix to develop 3D tissue-like models of the human lymph node and bone marrow, which were matured inside bioreactors under dynamic perfusion of medium. Comparing static and dynamic cultures of these 3D constructs revealed that perfusion promoted a tissue-like internal organization of cells, characterized by the expression of specific functional markers and deposition of an intricate extracellular matrix protein network. Recirculation of CLL cells within the dynamic system led to changes in leukemic cell behavior and in the expression of key markers involved in tumor progression. These findings suggest that the model is well suited for investigating the pathophysiological mechanisms of CLL and potentially other hematological malignancies.

Chronic myeloid leukemia (CML) is a leading example of a malignancy where a molecular targeted therapy revolutionized treatment but has rarely led to cures. Overcoming tyrosine kinase inhibitor (TKI) drug resistance remains a challenge in the treatment of CML. We have recently identified miR-185 as a predictive biomarker where reduced expression in CD34 + treatment-naïve CML cells was associated with TKI resistance. We have also identified PAK6 as a target gene of miR-185 that was upregulated in CD34 + TKI-nonresponder cells. However, its role in regulating TKI resistance remains largely unknown. In this study, we specifically targeted PAK6 in imatinib (IM)-resistant cells and CD34 + stem/progenitor cells from IM-nonresponders using a lentiviral-mediated PAK6 knockdown strategy. Interestingly, the genetic and pharmacological suppression of PAK6 significantly reduced proliferation and increased apoptosis in TKI-resistant cells. Cell survivability was further diminished when IM was combined with PAK6 knockdown. Importantly, PAK6 inhibition in TKI-resistant cells induced cell cycle arrest in the G2-M phase and cellular senescence, accompanied by increased levels of DNA damage-associated senescence markers. Mechanically, we identified a PAK6-mediated MDM2-p21 axis that regulates cell cycle arrest and senescence. Thus, PAK6 plays a critical role in determining alternative cell fates in leukemic cells, and targeting PAK6 may offer a therapeutic strategy to selectively eradicate TKI-resistant cells.

Astrocytes, a subtype of glial cells, have multiple roles in regulating neuronal development and homeostasis. In addition to the typical mammalian astrocytes, in the primate cortex, interlaminar astrocytes are located in the superficial layer and project long processes traversing multiple layers of the cerebral cortex. Previously, we described a human stem cell based chimeric mouse model where interlaminar astrocytes develop. Here, we utilized this model to study the calcium signaling properties of interlaminar astrocytes. To determine how interlaminar astrocytes could contribute to neurodevelopmental disorders, we generated a chimeric mouse model for Fragile X syndrome (FXS). We report that FXS interlaminar astrocytes exhibit hyperexcitable calcium signaling and are associated with dendritic spines with increased turnover rate.

Schwann cells (SCs) play a crucial role in peripheral nerve repair by supporting axonal regeneration and remyelination. While extensive research has been conducted using rodent SCs, increasing attention is being directed toward human SCs due to species-specific differences in phenotypical and functional properties, and accessibility of human SCs derived from diverse sources. A major challenge in translating SC-based therapies for nerve repair lies in the inability to replicate human SC myelination in vitro, posing a significant obstacle to drug discovery and preclinical research. In this study, we compared the myelination capacity of human, rodent, and porcine SCs in various co-culture conditions, including species-matched and cross-species neuronal environments in a serum-free medium. Our results confirmed that rodent and porcine SCs readily myelinate neurites under standard culture conditions after treatment with ascorbic acid for two weeks, whereas human SCs, at least within the four-week observation period, failed to show myelin staining in all co-cultures. Furthermore, we investigated whether cell culture manipulation impairs human SC myelination by transplanting freshly harvested and predegenerated human nerve segments into NOD-SCID mice for four weeks. Despite supporting host axonal regeneration into the grafts, human SCs exhibited very limited myelination, suggesting an intrinsic species-specific restriction rather than a cell culture-induced defect. These observations suggest fundamental differences between human and rodent SCs and highlight the need for human-specific models and protocols to advance our understanding of SC myelination.

This study focuses on improving the identification of chicken primordial germ cells (PGCs), which are vital for genetic transmission and biotechnological applications. Traditional markers like SSEA1 and CVH have limitations—SSEA1 lacks specificity, and CVH is intracellular. A monoclonal antibody was generated by injecting chicken PGCs into mice, producing one that specifically binds to PGCs and decreases with cell differentiation. Mass spectrometry identified its target as the MYH9 protein. The resulting αMYH9 antibody effectively labels PGCs at various developmental stages, offering a valuable tool for isolating viable PGCs and advancing avian genetics, agriculture, and biotechnology.