Biology subjects

Ping, X.

Publications and source records attributed to Ping, X..

7 recordsLinked to original sources

bioRxiv2026

Dual blockade of IL-18 and IL-4Rα by a bispecific antibody for improved treatment of atopic dermatitis

Background: Atopic dermatitis (AD) is a chronic inflammatory dermatosis primarily driven by type 2 immunity, with additional type 1 and type 3 components that may limit the benifit of ILRalpha blockade alone. Interleukin18 (IL18), an epithelial alarmin genetically associated with AD and correlated with disease severity, has been implicated as an upstream amplifier of this mixed inflammatory response. Objective: To assess whether concurrent IL18 neutralization and IL4Ralpha; blockade with a bispecific antibody provides broader and more balanced suppression of AD relevant type 1, type 2, and type 3 pathways than single target inhibition. Methods: We generated FJ0125, a bispecific antibody comprising human IL18 binding protein fused to a novel humanized anti IL4Ralpha antibody, and characterized its binding, signaling, and functional activity in vitro and in vivo. The activity was evaluated in human group 2 innate lymphoid cell and primed Th2 cell assays, a keratinocyte & dendritic cell & T cell coculture system, and an MC903/Staphylococcus aureus induced dermatitis model in human IL4/IL4Ralpha; knock in mice. Results: FJ0125 bound to IL18 and IL4Ralpha; with high affinity, engaged both targets, inhibited IL4/IL13 signaling with dupilumab comparable potency, and neutralized human and mouse IL18. In vitro, FJ0125 more effectively suppressed IL18 driven lymphocyte activation and type 1, type 2, and type 3 cytokine production than IL18BPFc or IL4Ralpha; monotherapy. In vivo, FJ0125 reduced multitype cytokines, improved dermatitis, lowered serum IgE, and abrogated the paradoxical IL22 increase observed with selective IL4Ralpha; blockade. Conclusion: Dual IL18/IL4Ralpha; blockade with FJ0125 achieves coordinated suppression of multitype inflammation and represents a mechanistically substantiated therapeutic strategy for AD.

immunology↗

bioRxiv2026

TDP-43 self-assembly is regulated by its disordered NLS-region

Cytosolic inclusions of the RNA-binding protein TDP-43 are a pathological hallmark of several neurodegenerative diseases, such as amyotrophic lateral sclerosis and frontotemporal dementia. Cellular or animal model systems often use TDP-43 mutated in its nuclear localization signal (NLS) to study its cytosolic mislocalization and aggregation. Here we show that the disordered NLS-region, in particular the basic amino acids, are crucial for self-assembly of full-length TDP-43 across size scales, ranging from small clusters to visible condensates and aggregates. Molecular dynamics simulations and NMR studies suggest that the NLS-region engages in inter-chain interactions with C-terminal aromatic residues as well as RRM1 and NTD interactions. We further demonstrate that a minimal NLS mutation (K82A) preserves TDP-43 condensation in vitro and in cells, while commonly used NLS mutations yield partially or strongly reduced self-assembly behaviors. Our data highlight TDP-43 K82A as ideal model system to study cytosolic TDP-43 aggregation in cell and animal models.

biochemistry↗

bioRxiv2026

Multi-Domain Interplay Controls Full-Length TDP-43 Phase Separation and Condensate Dynamics

TDP-43 (TAR DNA-binding protein 43) is a 414-amino acid protein with a structured N-terminal domain (NTD), two RNA recognition motifs (RRM1 and RRM2), and a long disordered C-terminal low complexity domain (LCD). TDP-43 forms phase-separated condensates as part of its physiological function in RNA processing. However, aberrant TDP-43 condensation, changes in condensate material properties, and subsequent aggregation are linked to the development of neurodegenerative diseases. Using explicit-solvent, near-atomic resolution coarse-grained simulations we demonstrate how the interplay among different domains drives phase separation of the full-length protein.We directly capture how the secondary structure of a conserved helix in the LCD modulates phase separation, and follow the effect of phosphomimicking mutations on the condensation of full-length TDP-43. C-terminal phosphomimicking mutations rewire the interactions of the LCD by increasing solvation locally and enhancing Na+ binding to the LCD. Our simulations and in vitro experiments emphasize the importance of the aromatic residues in the LCD but also of N-terminal residues 1-101 including the NTD for full-length TDP-43 condensation. With a G[o]-type approach we capture not just conformational flexibility but also specific dimer formation through NTD-NTD interactions and how they modulate the phase behavior as well as the dynamic and interfacial properties of full-length TDP-43 condensates.

biophysics↗

bioRxiv2025

Endurance Exercise Ameliorates Aging-Related Bradyarrhythmia in Drosophila Resulting from miR-283 Knockdown in LNvs

MicroRNAs (miRNAs) are crucial in regulating cardiac aging and related diseases, yet few functional miRNAs have been identified. Prior studies showed miR-216a upregulation in heart failure patients, but its impact on aging hearts is unknown. Our study revealed systemic miR-283 overexpression or knockdown caused age-related bradycardia, mimicking human bradyarrhythmia. Importantly, we found that knockdown of miR-283 in ventral-lateral neurons (LNvs), rather than in the heart, led to the occurrence of bradyarrhythmia, which was mainly caused by the upregulation of miR-283 expression in the whole brain and heart. The gene of clockwork orange (cwo) may mediate miR-283s effect on heart rhythm. Additionally, to investigate the miRNA regulatory mechanism underlying exercise-induced delay in cardiac aging, we conducted a three-week endurance exercise program on miR-283 knockdown flies in LNvs. We found that exercise significantly downregulated the accumulation of miR-283 in the brain and myocardium caused by aging or miR-283 knockdown in LNvs, improved the structure of myocardial fibers, and effectively reduced bradyarrhythmia. Our findings provides a new perspective on distal neuromodulation and intervention in cardiac aging.

physiology↗

bioRxiv2024

Distinct functions of PAXX and MRI during chromosomal end joining

A key step of Canonical Nonhomologous End Joining (C-NHEJ) is synapsis of DNA double strand break (DSB) ends for ligation. The DNA-PKcs dimer mediates synapsis in a long-range complex with DSB ends remaining apart, whereas the XLF homodimer can mediate synapsis in both long-range and short-range complexes. Recent structural studies found the PAXX homodimer may also facilitate synapsis in long-range complexes with DNA-PKcs via its interactions with Ku70. Thus, we examined the influence of PAXX in C-NHEJ of chromosomal DSBs, which we compared to another Ku-binding factor, MRI. Using EJ of blunt DSBs with Cas9 reporters as a readout for C-NHEJ, we found that PAXX and/or MRI are dispensable. However, when combined with disruption of DNA-PKcs, particularly with DNA-PKcs kinase inhibition, PAXX becomes important for blunt DSB EJ. In contrast, while DNA-PKcs is also important to suppress short deletion mutations with microhomology, this effect is not magnified with PAXX loss. MRI loss had no effect combined with DNA-PKcs disruption, but becomes important for blunt DSB EJ when combined with disruption of XLF, as is PAXX. Finally, XLF loss causes an increase in larger deletions compared to DNA-PKcs inhibition, which is magnified with combined loss of MRI. Altogether, we suggest that PAXX promotes DSB end synapsis during C-NHEJ in a manner that is partially redundant with DNA-PKcs and XLF, whereas MRI appears to be mainly important in the context of XLF disruption. SIGNIFICANCE STATEMENTCanonical Nonhomologous End Joining (C-NHEJ) is a DNA double strand break repair pathway that can repair diverse types of DNA ends, but is prone to causing genetic mutations. In particular, C-NHEJ can cause insertion or deletion mutations that can cause human disease. Therefore, it is critical to understand the mechanisms of C-NHEJ, including and how various factors within the pathway affect repair outcomes. In this study, we elucidate the role of factors PAXX and MRI during chromosomal EJ and their interplay with the C-NHEJ factors DNA-PKcs and XLF.

genetics↗

bioRxiv2023

RAD52 and ERCC6L/PICH have a compensatory relationship for genome stability in mitosis.

The mammalian RAD52 protein is a DNA repair factor that has both strand annealing and recombination mediator activities, yet is dispensable for cell viability. To characterize genetic contexts that reveal dependence on RAD52 to sustain cell viability (i.e., synthetic lethal relationships), we performed genome-wide CRISPR knock-out screens. Subsequent secondary screening found that depletion of ERCC6L in RAD52-deficient cells causes reduced viability and elevated genome instability, measured as accumulation of 53BP1 into nuclear foci. Furthermore, loss of RAD52 causes elevated levels of anaphase ultrafine bridges marked by ERCC6L, and conversely depletion of ERCC6L causes elevated RAD52 foci both in prometaphase and interphase cells. These effects were enhanced with combination treatments using hydroxyurea and the topoisomerase II inhibitor ICRF-193, and the timing of these treatments are consistent with defects in addressing such stress in mitosis. Thus, loss of RAD52 appears to cause an increased reliance on ERCC6L in mitosis, and vice versa. Consistent with this notion, combined depletion of ERCC6L and disrupting G2/M progression via CDK1 inhibition causes a marked loss of viability in RAD52-deficient cells. We suggest that RAD52 and ERCC6L play compensatory roles in protecting genome stability in mitosis.

cell biology↗

bioRxiv2020

Preferential Pharmacological Inhibition of Nav1.6, but not Nav1.1, Abolishes Epileptiform Activity Induced by 4-AP in Mouse Cortical Slices

Brain isoforms of voltage-gated sodium channels (VGSCs) have distinct cellular and subcellular expression patterns as well as functional roles that are critical for normal physiology as aberrations in their expression or activity lead to pathophysiological conditions. In this study, we asked how inhibition of select isoforms of VGSCs alters epileptiform activity to further parse out the roles of VGSCs in the brain. We first determined the relative selectivity of recently discovered small molecule, aryl sulfonamide, inhibitors (ICA-121431 and Compound 801) against Nav1.1, Nav1.2, and Nav1.6 activity using whole-cell patch clamp recordings obtained from HEK293 cells. To test the effects of these inhibitors on epileptiform activity, we obtained multielectrode array (MEA) recordings from mouse cortical slices in the presence of 4-aminopyridine (4-AP) to induce epileptiform activity. We found that the ICA-121431 and Compound 801 compounds are relatively selective for Nav1.1 and Nav1.6, respectively. From the MEA recordings, we found that inhibition of Nav1.6 and Nav1.2 with 500nM of the Compound 801 compound completely abolishes ictal local field potentials induced by 4-AP, whereas inhibition of Nav1.1 with 500nM of the ICA-121431 compound had minimal effect on epileptiform activity induced by 4-AP. Due to the prominent expression of Nav1.1 in inhibitory neurons, we asked whether inhibition of Nav1.1 alone alters activity. We found that, indeed, inhibition of Nav1.1 with the ICA-121431 compound increased basal activity in the absence of 4-AP. These findings expand our current understanding of the roles of VGSC isoforms in the brain and suggest that selective targeting of Nav1.6 may be a more efficacious treatment strategy for epileptic syndromes.

neuroscience↗