Biology subjects

Gaedke, F.

Publications and source records attributed to Gaedke, F..

5 recordsLinked to original sources

bioRxiv2026

Mitochondrial turnover at central GABAergic synapses governs vulnerability to epileptic seizures

Mitochondrial dysfunction has long been known to underlie neurodegeneration, yet the contribution of mitochondrial turnover dynamics to functional aspects of defined synaptic circuits remains poorly understood. Here, we show that the mitochondrial proteome and turnover rates of hippocampal glutamatergic and GABAergic neurons is differentially remodelled by experience, with distal axon terminals of somatostatin-positive neurons exhibiting most dramatic changes, suggesting a form of metabolic plasticity at GABAergic synapses coupled to circuit activity. Conditional ablation of the mitochondrial transport proteins MIRO1 or TRAK1 (whose human mutations cause congenital epilepsy) stalled turnover at axon terminals driving loss of cristae, without affecting synapse or neuron integrity. The resulting reduction in synaptic GABA levels destabilized network oscillations and led to hyperexcitability, culminating in recurrent seizures and premature death. Post-weaning gene therapy efficiently reversed mitochondrial alterations and ameliorated the epileptic phenotype, underscoring the crucial role of mitochondrial turnover at central GABAergic synapses for balancing network excitability.

neuroscience↗

bioRxiv2025

Single recipient cell tracking of tellurium-labeled extracellular vesicle proteomes (TeLEV) identifies EV-driven immunomodulation

Extracellular vesicles (EVs) mediate tumor-immune cell communication by carrying protein cargo that can immediately modulate signaling and antigen presentation. Yet mapping the uptake of primary EV proteomes by human immune cells at single-cell resolution has been constrained by a lack of labeling strategies. We show here that TeLEV, a tellurium-based metabolic mass tagging approach that incorporates L-2-tellurienylalanine (TePhe) into EV proteomes, can produce a biologically rare monoisotopic signal, which is detectable by mass cytometry, imaging mass cytometry, and nanoscale SIMS, without perturbing EV morphology, yield, or proteome composition. We applied TeLEV to label primary malignant B-cell-derived EVs (MBC-EVs) from chronic lymphocytic leukemia (CLL) patients and could follow EV uptake by distinct cell populations of healthy donor peripheral blood mononuclear cells. MBC-EV uptake occurred predominantly in cells of myeloid lineages. In direct control experiments with matched secreted proteins, a machine learning approach identified CD123, CD127, and CD25 as key markers distinguishing primary MBC-EV recipients from matched secreted protein recipient cells. Nanoscale imaging enabled localization of EV-delivered proteins within heterochromatin, whereas Te-labeled secreted proteins accumulated in the cytoplasm of recipient cells. We then generated a pan-immune EV uptake atlas by tracing the uptake of primary and cell-line EVs from nine cell lines and six donors with chronic lymphocytic leukemia into 2,977,094 recipient cells across 43 cell types and subpopulations. We found that the uptake of MBC-EVs by myeloid recipients induced monocyte-derived dendritic-cell polarization characterized by the co-expression of the interleukin-receptor triad (IL-RT: CD123, CD127, CD25) identified above. Time-resolved EV uptake analysis showed a rapid, transient expression of CD123/CD127 followed by CD25, both tightly coupled to MBC-EV uptake by myeloid cells. The intensity of IL-RT expression correlated with that of PD-L1 and BCL-2. Using different STAT degraders to bidirectionally modify the EV-induced STAT5 signal, we observed that MBC-EV uptake and IL-RT, PD-L1, and BCL-2 expression increased with STAT3 degradation and decreased with STAT5 degradation. To investigate the functional consequences of the MBC-EV-induced changes, we showed that MBC-EVs in the presence of IL-2 induced a high-CD25 immune state with low cytotoxic and high B cell proliferation. Taken together, TeLEV represents a novel tool for single-cell tracking of EV proteomes, revealing STAT5-dependent immune remodeling of recipient cells.

cancer biology↗

bioRxiv2025

Mechanical forces drive mitochondrial matrix extrusion and apoptotic pore growth

Apoptotic pore opening by BAX and BAK at the mitochondrial outer membrane is a key step in the cell commitment to death. The subsequent inner membrane extrusion and permeabilization releases mitochondrial DNA into the cytosol, which can trigger inflammatory signaling. However, the underlying mechanisms have not been elucidated. Here we developed CLOSE microscopy, a multi-correlative approach that enabled the simultaneous analysis of BAK stoichiometry and nanoscale organization in individual apoptotic pore complexes in relation to mitochondrial ultrastructure. We find that the outer membrane opening at the apoptotic pore defines the spatial arrangement of BAK nanoassemblies. We identify mechanical stress as a driver of inner membrane extrusion, which can be perturbed by osmoregulation. The extruded inner membrane in turn exerts forces on the outer membrane that promote apoptotic pore growth, in line with membrane dynamics simulations. Our study reveals a tight interplay between the inner and outer membranes during mitochondrial permeabilization in apoptosis and establishes a biophysical mechanism for inner membrane extrusion that defines the structural organization of the apoptotic pore.

cell biology↗

bioRxiv2024

Lysosomal uptake of mtDNA mitigates heteroplasmy

Mitochondrial DNA is exposed to multiple insults produced by normal cellular function. Upon mtDNA replication stress the mitochondrial genome transfers to endosomes where it is degraded. Here, using proximity proteomics we found that mtDNA replication stress leads to the rewiring of the mitochondrial proximity proteome, increasing mitochondria association with lysosomal and vesicle-associated proteins, such as the GTPase RAB10 and the retromer. We found that upon mtDNA replication stress, RAB10 enhances mitochondrial fragmentation and relocates from the ER to lysosomes containing mtDNA. The retromer enhances and coordinates the expulsion of mitochondrial matrix components through mitochondrial-derived vesicles, and mtDNA with direct transfer to lysosomes. Using a Drosophila model carrying a long deletion on the mtDNA ({Delta}mtDNA), we evaluated in vivo the role of the retromer in mtDNA extraction and turnover in the larval epidermis. The presence of {Delta}mtDNA elicits the activation of a specific transcriptome profile related to counteract mitochondrial damage. Expression of the retromer component Vps35 is sufficient to restore mtDNA homoplasmy and mitochondrial defects associated with {Delta}mtDNA. Our data reveal novel regulators involved in the specific elimination of mtDNA. We demonstrate that modulation of the retromer in vivo is a successful mechanism to restore mitochondrial function associated with mtDNA damage.

cell biology↗

bioRxiv2023

Enhanced mitochondrial fusion during a critical period of synaptic plasticity in adult-born neurons

Integration of new neurons into adult hippocampal circuits is a process coordinated by local and long-range synaptic inputs. To achieve stable integration and uniquely contribute to hippocampal function, immature neurons are endowed with a critical period of heightened synaptic plasticity, yet it remains unclear which mechanisms sustain this form of plasticity during neuronal maturation. We found that, as new neurons enter their critical period, a transient surge in fusion dynamics stabilizes elongated mitochondrial morphologies in dendrites to fuel synaptic plasticity. Conditional ablation of fusion dynamics to prevent mitochondrial elongation selectively impaired spine plasticity and synaptic potentiation, disrupting neuronal competition for stable circuit integration, ultimately leading to decreased survival. Despite profuse mitochondrial fragmentation, manipulation of competition dynamics was sufficient to restore neuronal survival, but left neurons poorly responsive to experiences at the circuit level. Thus, by enabling synaptic plasticity during the critical period, mitochondrial fusion facilitates circuit remodeling by adult-born neurons.

neuroscience↗