Lopez-Pigozzi, D. | bioRxiv Science

bioRxiv2025

Leukemic Cells Manipulate MSCs Bioelectrical Signals to Reshape the Bone Marrow Niche

Mesenchymal stromal cells (MSCs) are key components of the tumor microenvironment (TME), influencing leukemia progression through poorly understood mechanisms. We investigated the bioelectrical properties of MSCs derived from pediatric AML patients (AML-MSCs) and identified a significant depolarization of their resting membrane potential (Vmem, -14.7mV) compared to healthy MSCs (h-MSCs, -28.5mV), accompanied by downregulation of CaV1.2 L-type calcium channel expression. AML-MSCs displayed increased spontaneous calcium oscillations, suggesting altered ion homeostasis. Notably, h-MSCs exposed to AML blasts underwent a similar Vmem depolarization (-11.8mV) and CaV1.2 downregulation, indicating that leukemic cells actively reprogram MSCs. Functionally, Vmem depolarization in h-MSCs promoted a pro-leukemic phenotype, whereas hyperpolarization of AML-MSCs restored a normal behavior. CaV1.2 over-expression by lentiviral vectors in AML-MSCs shifted Vmem toward hyperpolarization and partially reversed their leukemia-supportive properties, in part through CaV1.2 transfer via tunneling nanotubes. These findings reveal that AML blasts impose a bioelectrical signature on MSCs, modulating ion channel activity to sustain a leukemic niche. Targeting this electrical reprogramming through CaV1.2 restoration represents a potential strategy to re-establish homeostasis in the bone marrow microenvironment.

cancer biology↗

bioRxiv2022

Structure of the connexin-43 gap junction channel reveals a closed sieve-like molecular gate

Gap junction channels (GJCs) mediate intercellular communication by connecting two neighboring cells and enabling direct exchange of ions and small molecules. Cell coupling via connexin-43 (Cx43) GJCs is important in a wide range of cellular processes in health and disease 1-3, yet the structural basis of Cx43 function and regulation has not been determined until now. Here we describe the structure of a human Cx43 GJC solved by cryo-EM and single particle analysis at 2.26 [A] resolution. The pore region of Cx43 GJC features several lipid-like densities per Cx43 monomer, located close to a putative lateral access site at the monomer boundary. We found a previously undescribed conformation on the cytosolic side of the pore, formed by the N-terminal domain and the transmembrane helix 2 of Cx43 and stabilized by a small molecule. Structures of the Cx43 GJC and hemichannels in nanodiscs reveal a similar gate arrangement. The features of the Cx43 GJC and hemichannel cryo-EM maps and the channel properties revealed by molecular dynamics simulations suggest that the captured states of Cx43 are consistent with a closed state.

biochemistry↗