Biology subjects

Eggers, C.

Publications and source records attributed to Eggers, C..

4 recordsLinked to original sources

bioRxiv2025

A dietary pan-amino acid dropout screen in vivo reveals a critical role for histidine in T-ALL

Dietary interventions show therapeutic potential in cancer, but systematic comparisons are lacking. We performed a dietary pan-amino acid dropout screen in an orthotopic model of NOTCH1-driven T-cell acute lymphoblastic leukemia and identified histidine depletion as uniquely antileukemic. Histidine-restricted diets extended survival of leukemic mice in a dose-dependent manner, while remaining well-tolerated. Mechanistically, multiomic profiling revealed that histidine deprivation-induced ribosome stalling activates GCN2 to suppress cholesterol biosynthesis pathways critical for leukemic proliferation. Dietary cholesterol supplementation partially reverted the antileukemic effects of histidine restriction in vivo. These findings couple histidine levels and translational control to cholesterol metabolism, which can be therapeutically exploited for cancer treatment. Our results suggest that defined dietary amino acid restrictions may expose broader therapeutic opportunities in diseases beyond cancer.

cancer biology↗

bioRxiv2025

tRNA thiolation defects disrupt cellular proteostasis and tissue homeostasis in mammals

Sulfur modification of tRNA wobble uridines is an evolutionarily conserved mechanism that ensures efficient protein synthesis. In humans, loss of this anticodon modification due to mutations in CTU2 (cytosolic thiouridylase 2) causes DREAM-PL syndrome, a severe congenital disorder often leading to early postnatal death. However, the mechanisms by which loss of tRNA thiolation drives pathology remain unclear. Here, we show that loss of CTU2 triggers significant cellular proteostasis defects in patient cells and model cell lines. Structural and biochemical analyses reveal that the pathogenic CTU2L63P mutation destabilizes the CTU1/CTU2 complex and abolishes tRNA binding and thiolation. Acute loss of CTU2 caused codon-specific ribosome pausing at A-ending codons decoded by thiolated tRNAs, and decreased ribosome occupancy of A-rich transcripts in a dosage-dependent manner. Codon-biased mRNAs transcribed from genes critical for ciliogenesis are predicted to be most affected, linking their reduced translation to DREAM-PL etiology in humans. Surprisingly, Ctu2L63P mice display severe thiolation defects, but develop normally, are viable and fertile. Our findings highlight the importance of functional tRNA thiolation for organismal health in humans and identify species-specific vulnerabilities during embryonic development in mammals.

cell biology↗

bioRxiv2024

Dynamic properties in functional connectivity changes and striatal dopamine deficiency in Parkinson's disease

IntroductionRecent studies in Parkinsons disease (PD) patients reported disruptions in dynamic functional connectivity (dFC, i.e., a characterization of spontaneous fluctuations in functional connectivity over time). Here, we assessed whether the integrity of striatal dopamine terminals directly modulates dFC metrics in separate PD cohorts, indexing dopamine-dependent changes in large-scale brain network dynamics and its implications in clinical features. MethodsWe pooled data from two cohorts reflecting early PD. From the Parkinsons Progression Marker Initiative (PPMI) cohort, resting-state functional magnetic resonance imaging (rsfMRI) and dopamine transporter (DaT) SPECT were available for 63 PD patients and 16 age- and sex-matched healthy controls. From the clinical research group 219 (KFO) cohort, rsfMRI imaging was available for 52 PD patients and 17 age- and sex-matched healthy controls. A subset of 41 PD patients and 13 healthy control subjects additionally underwent 18F-DOPA-PET imaging. The striatal synthesis capacity of 18F-DOPA PET and dopamine terminal quantity of DaT SPECT images were extracted for the putamen and the caudate. After rsfMRI pre-processing, an independent component analysis was performed on both cohorts simultaneously. Based on the derived components, an individual sliding window approach (44s window) and a subsequent k-means clustering were conducted separately for each cohort to derive dFC states (reemerging intra- and interindividual connectivity patterns). From these states we derived temporal metrics, such as average dwell time per state, state attendance, and number of transitions and compared them between groups and cohorts. Further, we correlated these with the respective measures for local dopaminergic impairment and clinical severity. ResultsIn both cohorts, dFC analysis resulted in three distinct states, varying in connectivity patterns and strength. In the PPMI cohort, PD patients showed a lower state attendance for the globally integrated (GI) state (X2(1, N=79) = 5.82, p= 0.016) and a lower number of transitions (U(N=79) = 337.5, z = -2.06 p= .039) than controls. Significantly, worse motor scores (UPDRS-III) and dopaminergic impairment in the putamen and the caudate were associated with low average dwell time in the GI state (UPDRS-III: {tau}b(N=63) = -.281; p =.003, DaT putamen: {tau}b(N=63)=.213, p= .023, DaT caudate: {tau}b(N=63)=.209, p= .025) and a low total number of transitions (UPDRS-III: {tau}b(N=63)= -.308; p = .001, DaT putamen: {tau}b(N=63)=.350, p<.001, DaT caudate: {tau}b(N=63)=.251, p=.007). Additionally, worse motor performance was associated with a low number of bi-directional transitions between the GI and the lesser connected (LC) state ({tau}b(N=63)= -.237; p =.019). These results could not be reproduced in the KFO cohort: No group differences in dFC measures or associations between dFC variables and dopamine synthesis capacity or clinical measure were observed. ConclusionIn early PD, relative preservation of motor performance may be linked to a more dynamic engagement of an interconnected brain state. Specifically, those large-scale network dynamics seem to depend on striatal dopamine availability. Notably, we obtained these results in only one cohort, but not in a replication sample. Key pointsO_LIExploring dopamines role in brain network dynamics in two Parkinsons disease (PD) cohorts, we unraveled PD-specific changes in dynamic functional connectivity (dFC). C_LIO_LIIn the discovery cohort, results suggest striatal dopamine availability influences large-scale network dynamics that are relevant in motor control. C_LIO_LIIn the confirmation cohort, these findings were not replicated, indicating PD-specific dFC changes are dependent on unrecognized cohort features. C_LI

neuroscience↗

bioRxiv2024

Codon Pair-Specific Translation Defects Trigger Ribosome-Associated Quality Control to Avoid Proteotoxic Stress

tRNA modifications tune translation rates and codon optimality, thereby optimizing co-translational protein folding, but how codon optimality defects trigger cellular phenotypes remains unclear. Here, we show that ribosomes stall at specific modification-dependent codon pairs, triggering ribosome collisions and inducing a coordinated and hierarchical response of cellular quality control pathways. Ribosome profiling reveals an unexpected functional diversity for wobble-uridine (U34) modifications during decoding. The same modification can have different effects at the A and P sites. Furthermore, modification-dependent stalling codon pairs induce ribosome collisions, triggering ribosome-associated quality control (RQC) to prevent protein aggregation by degrading aberrant nascent peptides and mRNAs. RQC inactivation stimulates the expression of molecular chaperones to remove protein aggregates. Our results show that loss of tRNA modifications primarily disrupts translation rates of suboptimal codon pairs and reveal the coordinated regulation and adaptability of cellular surveillance systems to ensure efficient and accurate protein synthesis and maintain protein homeostasis.

biochemistry↗