Biology subjects

Chauhan, B. S.

Publications and source records attributed to Chauhan, B. S..

7 recordsLinked to original sources

bioRxiv2026

UPLC-ESI-MS based lipidomics revealed novel biomarkers in insulin receptor knockdown induced type 2 diabetes model of Drosophila

Type 2 diabetes (T2D) is a prevalent metabolic disorder affecting millions worldwide, characterized by insulin resistance and impaired glucose homeostasis. While mammalian models are widely used, Drosophila melanogaster provides a powerful alternative due to its conserved insulin signaling pathways, genetic tractability, and suitability for high throughput studies. In addition to glucose dysregulation, lipid metabolism plays a crucial role in T2D pathophysiology, as alterations in lipid composition contribute to insulin resistance and metabolic dysfunction. Lipidomic studies have emerged as an essential approach to identify metabolic signatures and potential biomarkers for disease progression and therapeutic targeting. In this study, T2D like model was established by inducing insulin resistance through knockdown of the insulin receptor in brain insulin-producing cells using the dilp2-Gal4>UAS-InRRNAi system. This genetic manipulation resulted in significant metabolic dysregulation, including elevated glucose, trehalose, and triacylglyceride levels, along with increased oxidative stress indicators. Additionally, mRNA expression analysis of key insulin signaling components, including insulin receptor substrate 1, dilp2, dilp3, dilp5, and phosphorylated Akt, further validated the model. To further investigate metabolic alterations, Lipid profiling was performed using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) in non targeted LC-MS-based metabolomics approach to identify lipid biomarkers associated with T2D. Multivariate statistical analyses, including PCA and PLS-DA, revealed distinct lipid signatures between wild-type and T2D flies. Notably, specific phosphatidylglycerol species PG 34:0, PG 34:4, PA 38:3, PIP 38:1, PIP2 38:6, and LPS 24:0 demonstrated an area under the curve (AUC) of 1, indicating their strong reliability as lipid biomarkers for T2D diagnosis.

biochemistry↗

bioRxiv2026

C9orf72-associated G4C2 hexanucleotide repeat expression in Drosophila mushroom bodies causes age dependent TDP-43 pathology and dementia relevant phenotypes mediated in part by the glypican Dlp/GPC6

Hexanucleotide repeat expansions (HREs) in C9orf72 are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), yet the age-, sex-, repeat-length-, and circuit-specific influence on the pathology of neurons remains incompletely understood. Here, we established a Drosophila model of C9orf72-associated dementia by expressing G4C2 repeats in mushroom body neurons (MBNs), a brain region critical for memory, locomotion, and sleep. Expression of 44X G4C2 repeats ((G4C2)44X) led to progressive axonal thinning, age-dependent accumulation of Repeat Associated Non-AUG (RAN) translated GR-GFP dipeptide repeat (DPR) puncta, premature nuclear-to-cytoplasmic mislocalization of endogenous TDP-43, increased caspase, reduced lifespan and a loss of presynaptic active zones. Behaviorally, (G4C2)44X expression caused locomotor hyperactivity, altered spatial working memory, and fragmentation of sleep architecture in an age- and sex-dependent manner, recapitulating core features of FTD. Surprisingly, the shorter (G4C2)12X repeat, traditionally considered a control, also produced detectable RAN translation and intermediate phenotypes in aging MBNs, suggesting that length- and tissue-associated factors modulate repeat toxicity. We further identified a repeat-length- and age-dependent reduction of the glypican Dally-like protein (Dlp) in (G4C2)44X consistent with disrupted Wnt-related signaling linked to TDP-43 proteinopathies. Restoring Dlp expression in MBNs mitigated locomotor and working-memory alterations, and loss of presynaptic active zones. In contrast, axonal degeneration, TDP-43 mislocalization, and lifespan were not significantly improved by restoring Dlp, suggesting that multiple mechanisms contribute to G4C2-induced toxicity. Supporting our findings in Drosophila MBNs, a CRISPRi screen in TDP-43 knock-down iNeurons identified GPC6, a human ortholog of Dlp, as a significant contributor to TDP-43 dependent synaptic loss. Together, our findings reveal an aging-sensitive, circuit-specific model of C9orf72-associated neurodegeneration and highlight roles for DPR accumulation and Dlp/GPC6 dependent synaptic loss in FTD pathomechanisms.

neuroscience↗

bioRxiv2026

Temporal tracking of Synaptobrevin-1 trafficking reveals SAM-4/BORC-dependent trafficking routes in C. elegans neurons

Synaptic vesicle proteins (SVPs) are synthesised in the neuronal soma trafficked as precursor synaptic vesicles (pre-SVs) on route to synapses. While pre-SVs are known to have heterogeneous protein composition and can co-traffic with lysosomal proteins. In this study, we assess the trafficking routes and kinetics of Synatobrevin-1 (SNB-1) released from the ER using the RUSH system in vivo in C. elegans touch receptor neurons. We showed that ER-released SNB-1 follows at least two temporally distinct trafficking routes. A predominantly anterogradely moving population of SNB-1 carrying vesicles appeared early, within 20 minutes of ER release in the axon without overlap with lysosomal proteins. Another SNB-1 population at 45 minutes post-ER release overlapped with endolysosomal compartments in both the cell body and the axon. Early SNB-1 carrying vesicles co-migrate with a transmembrane synaptic vesicle protein Synaptogyrin (SNG-1) and RAB-27 but fewer with RAB-3, suggesting that SVPs can be co-sorted into the same carriers prior to overlap with lysosomal proteins. The SV-lysosomal protein overlap occurs even when SNB-1 endocytosis on the plasma membrane is reduced in unc-11/ap180 mutants. Finally, we identified SAM-4/Myrlysin, a subunit of the BORC complex, as a regulator of both the trafficking kinetics of Synaptobrevin-1 intermediates and the cargo composition of pre-SVs. Loss of SAM-4 accelerated SV-lysosomal protein overlap and reduced co-transport of SNG-1 with SNB-1 in early pre-SVs in the axon. Together, these findings reveal heterogeneity in pre-SV biogenesis routes and identify SAM-4 as a key regulator of both the kinetics and cargo composition of synaptic vesicle precursors.

cell biology↗

bioRxiv2025

AP-3 complex sorts preferential cargo to govern dense core vesicle function in neuroendocrine cells

This study reveals new insights into the role of the Adaptor protein (AP-3) complex in dense core vesicle function. Despite numerous studies, an existing knowledge lacuna in the role of AP-3 in DCV function prompted us to delve deeper. Advanced microscopy and biochemical analysis revealed compromised DCV exocytosis in AP-3-depleted PC12 cells and C. elegans. AP-3 depletion altered the size and positioning of DCVs. Golgi defects and RUSH (Retention under Selective Hook) substantiated the role of AP-3 in trans-Golgi DCV budding. Proteomics revealed the loss of specific known and putative novel DCV proteins, which were mislocalized and rerouted to lysosomes in AP-3-depleted cells. Bioinformatics, Proximity ligation assays and Co-immunoprecipitation identified interactions of mislocalized proteins with AP-3 subunit. These findings corroborated with functional defects in granule maturation, release modes, Zinc and neurotransmitter mobilisation. Our study highlights the complexity of the AP-3 complex in regulating DCV function and its importance in vesicle transport in neurons and neuroendocrine cells. SummaryThis work reveals the critical role of AP-3 complex in DCV function, highlighting its impact on DCV exocytosis, positioning, and trans-Golgi budding. This study identifies Dlk1 as a novel DCV cargo.

cell biology↗

bioRxiv2025

BORC segregates synaptic vesicle and lysosomal proteins through motors UNC-104/KIF1A and UNC-116/KIF5

While synaptic vesicle proteins (SVPs) and lysosomal proteins can be present together in axons, the origin of these compartments is unclear. These SV-lysosomes are however thought to segregate further to SVPs and lysosomal proteins. In this study, we identify genes and characterize a genetic pathway involved in the segregation of SVPs and lysosomal proteins in the neuronal cell body. We identify a novel role for BORC (BLOC-1-related complex) in segregating SVPs and lysosomal proteins in the cell body. BORC subunit SAM-4/Myrlysin acts through ARL-8 and Kinesin motor proteins UNC-116/KIF5 and UNC-104/KIF1A in segregating SVPs and lysosomal proteins. Additionally, we also show that LRK-1/LRRK2 and APB-3/AP-3 ({beta}3), involved in pre-SV biogenesis, regulate the segregation of SVPs and lysosomal proteins in the neuronal cell body. LRK-1 recruits SAM-4 that in turn governs the localisation of APB-3 suggesting a hierarchical pathway of LRK-1-SAM-4-APB-3 for the segregation of SVPs and lysosomal proteins. Additionally, we also observe that the size of lysosomal protein-containing compartments (LPCCs) is smaller in SAM-4 and LRK-1. This size regulation depends on UNC-116. Together, we show that BORC recruited by LRK-1 and in turn via motors and along with AP-3 mediates the segregation of SVPs and lysosomal proteins in the neuronal cell body.

cell biology↗

bioRxiv2022

Identification of differentially expressed novel tau associated proteins in transgenic AD model of Drosophila - a proteomic and in silico Approach

Alzheimers disease (AD) is a memory related neurodegenerative disorder mainly associated with older adults. In this study, transgenic Drosophila AD model has been employed to investigate the tau associated proteome. Tau expression was specifically induced in the eye tissues and diseased fly heads were considered for proteomic studies with appropriate controls. We have identified 6 novel proteins from tau induced AD group by 2D and PD Quest analyses and further characterized them by in-vivo and in-silico approaches. The novel Tau interactors, [Obp44a Isoform A, Pglym Isoform A, IP15846p (Adh variant), RE45450p (mRpL2), Retinin, and Glob1 Isoform B], identified by MALDI-TOF/MS were validated through q-RT-PCR. The altered metabolic, behavioral and mitochondrial dynamics associated with Tau over expressing AD flies could be due to the altered expression of Odorant binding protein 44a (Obp44a) and mitochondrial ribosomal protein L2 (mRpL2), respectively. Further, we have showed for the first time the newly identified protein interaction with tau and other regulatory proteins through protein-protein docking, biocomputational classification and evolutionary relationship using in silico studies. Moreover, the study highlights the plausible role of these novel proteins in pathophysiology of phospho-tau induced AD flies and further help unraveling molecular pathways implicated in tauopathies.

neuroscience↗

bioRxiv2019

Growth behavior and glyphosate resistance level in 10 biotypes of Echinochloa colona in Australia

Recently, poor control of Echinochloa colona with glyphosate has been reported in no-till agriculture systems of the northern grain region (NGR) of Australia. Two experiments were conducted using 10 biotypes of E. colona selected from the NGR of Australia to understand differences in their growth behavior and resistance pattern. Growth studies revealed that these biotypes differed in plant height (53-70 cm plant-1), tiller production (30-52 tillers plant-1), leaf production (124-186 leaves plant-1) and seed head production (37-65 seed heads plant-1). Days taken to seed heads and shoot biomass in these biotypes ranged between 40-48 d and 21-27 g plant-1, respectively. Seed production in these biotypes ranged between 5380 and 10244 seeds plant-1; lowest for biotype B17/25 and highest for biotype B17/13. Correlation studies revealed that seed number plant-1 had a positive correlation with plant height (r = 0.67), tiller number plant-1 (r = 0.89), leaf number plant-1 (r = 0.73), seed heads plant-1 (r = 0.78), seed head weight (r = 0.79), shoot biomass (r = 0.77) and root biomass (r = 0.46). The glyphosate dose-response study showed a wide range of responses in these biotypes and the glyphosate dose required to reduce 50% biomass (GR50 values) was estimated between 217 to 2159 g a.e. glyphosate ha-1. GR50 values of biotypes B17/16, B 17/34 and B17/35 were 719, 2159 and 884 g ha-1, respectively, making them 3, 10 and 4-fold resistant to glyphosate compared with the susceptible biotype B17/37. Growth behavior and seed production potential in these biotypes had no correlation with the resistance index. These results suggest that some biotypes of E. colona are highly problematic; for example, biotype B17/34 was not only highly glyphosate-resistant, but also produced a high seed number (9300 seeds plant-1). This study demonstrated that there is a possibility of great risk with the increased use of glyphosate for managing E. colona in the NGR of Australia. The results warrant integrated weed management strategies and improved stewardship guidelines are required for managing glyphosate-resistant biotypes of E. colona and to restrict further movement of resistant biotypes to other regions of Australia.

ecology↗