Biology subjects

David, N.

Publications and source records attributed to David, N..

3 recordsLinked to original sources

bioRxiv2023

Loss of EIF4G2 Mediates Aggressiveness in Distinct Human Endometrial Cancer Subpopulations with Poorer Survival Outcome in Patients

The non-canonical translation initiation factor EIF4G2 plays essential roles in embryonic development and differentiation, and contributes to the cellular stress response via translation of selective mRNA cohorts. Currently there is limited and conflicting information regarding the potential involvement of EIF4G2 in cancer development and progression. Endometrial cancer (EC) is the most pervasive gynecological cancer in the developed world, with increasing incidence every year. High grade ECs are largely refractory to conventional treatments, presenting poor survival rates and lacking suitable prognostic markers. Here we assayed a cohort of 280 EC patients across different types, grades, and stages, and found that low EIF4G2 expression highly correlated with poor overall and recurrence free survival in Grade 2 EC patients, monitored over a period of up to 12 years. To establish a causative connection between low EIF4G2 expression and cancer progression, we analyzed in parallel two independent human EC cell lines and demonstrated that stable EIF4G2 knock-down resulted in increased resistance to conventional therapies. Depletion of EIF4G2 also increased the prevalence of molecular markers for aggressive cell subsets, and altered their transcriptional and proteomic landscapes. Prominent among the proteins with decreased abundance were Kinesin-1 motor proteins KIF5B and KLC1, 2, 3. Multiplexed imaging of the tumors from this EC patient cohort showed a correlation between decreased protein expression of either KIF5B or KLC1, and poor survival in patients of certain grades and stages. The findings herein reveal potential novel biomarkers for Grade 2 EC with potential ramifications for patient stratification and therapeutic interventions. SignificanceDecreased EIF4G2 protein results in increased drug resistance of aggressive sub-populations of endometrial cancer cells, is associated with poor patient survival, and may serve as a novel prognosis marker for endometrial cancer.

cancer biology↗

bioRxiv2023

Enhancing KCC2 function reduces interictal activity and prevents seizures in mesial temporal lobe epilepsy

The neuronal K/Cl cotransporter KCC2 regulates the transmembrane chloride gradient, which controls the efficacy of GABAergic signaling. In mesial temporal lobe epilepsy (mTLE) and other neurological disorders, reduced KCC2 expression or function can result in depolarizing GABA signaling, which is thought to contribute to pathological activity and seizures. Therefore, restoring chloride homeostasis represents a promising therapeutic strategy. We investigated the mechanisms and antiseizure effects of two small molecules, prochlorperazine (PCPZ) and CLP-257, that have been identified as potential KCC2 enhancers. We found that both compounds enhance KCC2 function and clustering in cortical neurons while reducing its membrane diffusion, without altering canonical regulatory phosphorylation. CLP-257 also selectively increased extrasynaptic, but not synaptic, GABAA receptor-mediated currents. Using in vitro recordings from resected brain tissue of patients with drug-resistant mTLE and in vivo recordings from a mouse model, we show that PCPZ and CLP-257 (or its prodrug CLP-290) effectively suppressed spontaneous epileptiform activity in both models. These findings reveal that PCPZ and CLP-257 act as genuine KCC2 enhancers and provide experimental evidence of the therapeutic potential of such compounds for treating drug-resistant mTLE. Significance statementA major challenge in treating epilepsy is the high percentage of patients with drug-resistant forms, like mesial temporal lobe epilepsy (mTLE). This study investigates a therapeutic strategy by targeting the neuronal KCC2 transporter, which is often dysfunctional in epilepsy. Our findings identify two compounds, prochlorperazine and CLP-257, that enhance KCC2 function by promoting its clustering on the cell membrane, a previously uncharacterized mechanism. Importantly, these compounds effectively reduce spontaneous epileptiform activity in human brain tissue from mTLE patients and significantly reduce seizure frequency in a mouse model. This work provides a critical proof-of-concept for activating KCC2 as a viable therapeutic approach for drug-resistant epilepsy.

neuroscience↗

bioRxiv2023

MiniBAR/KIAA0355 is a dual Rac and Rab effector required for ciliogenesis

Cilia protrude from the cell surface and play critical roles in in-tracellular signaling, environmental sensing and development. Actin-dependent contractility and intracellular trafficking are both required for ciliogenesis, but little is known about how these processes are coordinated. Here, we identified a Rac1-and Rab35-binding protein with a truncated BAR domain that we named MiniBAR (aka KIAA0355/GARRE) which plays a key role in ciliogenesis. MiniBAR colocalizes with Rac1 and Rab35 at the plasma membrane and on intracellular vesicles traffick-ing to the ciliary base and exhibits remarkable fast pulses at the ciliary membrane. MiniBAR depletion leads to short cilia resulting from abnormal Rac-GTP/Rho-GTP levels, increased acto-myosin-II-dependent contractility together with defective trafficking of IFT88 and ARL13B into cilia. MiniBAR-depleted zebrafish embryos display dysfunctional short cilia and hall-marks of ciliopathies including left-right asymmetry defects. Thus, MiniBAR is a unique dual Rac and Rab effector that con-trols both actin cytoskeleton and membrane trafficking for cili-ogenesis.

cell biology↗