Ex vivo expansion of hematopoietic stem cells (HSCs) is limited by culture-induced oxidative stress, yet the upstream transcriptional drivers remain poorly defined. Here, we show that the transcription factor Bcl11a is rapidly and persistently downregulated during HSC culture and that this decline drives functional deterioration. Bcl11a was both required and sufficient to maintain quiescence, clonogenic activity, and serially transplantable HSC function. Mechanistically, Bcl11a directly represses a Nox2 NADPH oxidase gene module, including Ncf1, encoding the p47phox organizer subunit; Ncf1 deletion reduced ROS and partially rescued the defects of Bcl11a-deficient HSCs. Rapamycin-but not the ROS scavenger N-acetylcysteine-restored Bcl11a expression, suppressed Ncf1 and ROS, and improved HSC function, identifying Bcl11a as a candidate effector linking mechanistic target of rapamycin complex 1 inhibition to redox control. This axis was conserved in human hematopoietic stem and progenitor cells, revealing a druggable transcriptional vulnerability of cultured HSCs and a framework for improving ex vivo-expanded grafts.
There is a higher density of immune cells in peritoneal fluid than is found in blood. Thus, any perturbations, from sterile injury to endometriosis to ovarian cancer, require immune cells to recognize and nucleate to these sites. Using peritoneal injuries as a prototype, we saw a massive recruitment of large peritoneal macrophages (LPMs) interspersed with mast cells. The mast cells were activated by sensory neurons to mobilize their 1-mu m granules to the cell surface. Lattice light sheet microscopy unveiled a new step in the mast cell degranulation. After granules fused with the plasma membrane, cytonemes (very thin long filopodia) grabbed the granules from the mast cell surface and deposited them on neighboring LPMs. The granules were membraneless biomolecular condensates and harbored more than 200 different proteins, including MARCO, which mediated rapid LPM aggregation to the injury nidus. The condensates also induced a repair-like phenotype in the macrophages that helped heal the injury site.
Recent genome-wide association studies have identified numerous Alzheimer’s disease (AD) risk genes enriched in microglia, including Crk-associated substrate (Cas) scaffold protein family member 4 (CASS4), which encodes the adaptor protein CASS4. Despite its strong genetic association with AD, the role of CASS4 in disease remains poorly understood. Here, we show that full-body Cass4 deletion in 5xFAD mice increases amyloid-β (Aβ) deposition, neuronal dystrophy, and cognitive deficits. Since microglia are the predominant brain-resident cells expressing Cass4, we investigated its role in microglial responses to Aβ pathology. Loss of CASS4 impaired microglial mobilization to Aβ plaques and reduced plaque compaction. Phosphoproteomic analysis of purified microglia revealed marked disruption of focal adhesion signaling following Cass4 deletion. Consistent with this, CASS4 deficiency abrogated in vivo microglial recruitment to injury and in vitro wound healing responses, two processes that are centrally orchestrated by focal adhesion biology. Together, these findings identify CASS4 as a critical regulator of microglial function and focal adhesion biology and suggest that CASS4 may represent a therapeutic target for AD.
Aberrant activation of dendritic cells (DCs) is intricately associated with inflammatory diseases, rendering DCs an appealing therapeutic target. Metabolites are emerging as crucial regulators of DCs, yet therapeutic strategies targeting DC metabolism for inflammatory diseases remain underexplored. Our study identifies the Vanin-pantethine-cholesterol axis as a key metabolic pathway that governs DC activation—a classical APC function. We found that Vanin is upregulated in activated DCs from autoimmune patients and mice; DC-specific Vanin deficiency significantly alleviates psoriasiform inflammation in mice. Mechanistically, Vanin hydrolyzes pantethine, leading to cholesterol and lipid raft accumulation on the cell membrane and promoting DC hyperactivation. Pantethine supplementation or pharmacologically induced Vanin inhibition reduces cholesterol overload, impedes DC activation, and mitigates psoriasiform inflammation. Notably, pantethine or RR6 treatment impairs activation of patient-derived DCs, and our investigator-initiated trial shows that pantethine combination therapy relieves clinical symptoms in psoriasis patients. Collectively, these findings establish the Vanin-pantethine-cholesterol axis as a key modulator of APC function, offering a promising metabolic approach for inflammatory diseases.
