Hematopoietic regeneration requires coordinated activation of hematopoietic stem and progenitor cells (HSPCs) and adaptive remodeling of the bone marrow (BM) microenvironment to meet extreme metabolic and oxidative demands imposed by cytotoxic injury, transplantation, and inflammation. While soluble factors and cytokine signaling are central to this process, emerging evidence identifies direct intercellular communication as a critical regulatory layer in stress hematopoiesis. Connexins, particularly Connexin-43 (Cx43), form an evolutionarily conserved communication network that integrates metabolic coupling, redox buffering, and organelle dynamics across hematopoietic and stromal compartments. Beyond canonical gap junction channel activity, connexins exert non-junctional, compartment-specific functions through cytoplasmic, nuclear, and mitochondrial pools that regulate signaling scaffolds, transcriptional programs, cytoskeletal organization, mitochondrial dynamics, calcium homeostasis, and bioenergetics. In HSPCs, mitochondrial Cx43 functions as a metabolic checkpoint that preserves regenerative capacity by supporting oxidative phosphorylation, limiting chronic AMPK activation, maintaining fusion-fission balance, and preventing mitochondrial Ca²⁺ overload. In parallel, Cx43 enables mitochondrial transfer from donor HSPCs to stromal niche cells, restoring stromal metabolic competence and promoting effective niche repair and engraftment. Dysregulation of connexin networks contributes to marrow failure, clonal evolution, leukemic niche remodeling, and chemoresistance, highlighting their context-dependent roles in health and disease. This review synthesizes advances in connexin biology in hematopoiesis, reframes connexins as integrators of metabolic and regenerative signaling rather than passive conduits, and defines emerging translational opportunities. Isoform- and compartment-specific targeting of connexin pathways offers a therapeutic strategy to enhance hematopoietic recovery, preserve long-term stem cell function, and disrupt pathological niche support in hematologic malignancies.
Singh et al. (Thu,) studied this question.