Biology subjects

Mahajan, N.

Publications and source records attributed to Mahajan, N..

9 recordsLinked to original sources

bioRxiv2026

TSC2 acting as a transcription factor for miR-514b-3p and regulating PI3K-AKT-MTOR pathway via nucleus

The PI3K-AKT-MTOR signalling pathway is pivotal in regulating cell survival, proliferation, and growth. TSC2 or tuberin acts as a key negative regulator of this pathway by forming a cytoplasmic complex with TSC1 and TBC1D7. While the cytoplasmic role of TSC2 is well established, emerging evidence suggests its nuclear functions. Previously, we have identified TSC2 as a transcriptional repressor of the EREG gene. Building on this foundation, the present study has investigated the transcriptional role of TSC2 in miRNA gene regulation. A genome-wide miRNA microarray profiling of TSC2-depleted SCC131 cells identified 19 upregulated and 24 downregulated miRNAs. Of these, miR-514b-3p emerged as one of the most upregulated miRNAs. The RT-qPCR analysis showed that TSC2 knockdown results in a robust miR-514b-3p upregulation, whereas TSC2 overexpression suppresses its expression in SCC131 cells. Moreover, TSC2 negatively regulates the MIR514B promoter activity in an NLS-dependent manner. Our ChIP analysis confirmed the direct binding of TSC2 to the MIR514B promoter, establishing miR-514b-3p as a transcriptional target of TSC2. We further identified TSPAN9 as a direct downstream target of miR-514b-3p. TSC2 positively regulates TSPAN9 levels by repressing miR-514b-3p, thereby establishing a novel TSC2/miR-514b-3p/TSPAN9 regulatory axis. We further uncovered a crosstalk between TSC2/miR-514b-3p/TSPAN9 axis and the canonical PI3K-AKT-MTOR signalling pathway, where miR-514b-3p positively and TSPAN9 negatively regulates this pathway. Interestingly, AKT functions as an upstream regulator of this axis by modulating the nuclear localization of TSC2. Collectively, this study provides new insights into the non-canonical, nucleus-dependent transcriptional functions of TSC2, thus expanding its role beyond cytoplasmic signalling regulation and underscoring its significance in the cellular signalling networks. Graphical abstractThe diagrammatic representation of the TSC2/miR-514b-3p/TSPAN9 axis and its interaction with the canonical PI3K-AKT-MTOR pathway. Abbreviations: PI3K, Phosphatidylinositol-3 kinase; TSC1, Tuberous sclerosis complex subunit 1; TSC2, Tuberous sclerosis complex subunit 2; TBC1D7, Tre2-Bub2-CDC16 domain family member 7; RHEB, Ras homolog enriched in brain; GTP, Guanosine tri phosphate; GDP, Guanosine di phosphate; MTORC1, Mechanistic target of rapamycin kinase complex 1; S6K1, p70 ribosomal protein S6 kinase; 4E-BP-1, eIF4E-binding protein 1; and TSPAN9, Tetraspanin 9. This figure was created in BioRender (https://app.biorender.com/).

cancer biology↗

bioRxiv2025

Long-term Dietary Fat Intervention Affects Retinal Health in APOE Mice

The APOE genotype influences metabolic and neurodegenerative outcomes, with APOE4 carriers at higher risk for Alzheimers disease (AD) and metabolic dysfunction. This study examines how long-term dietary interventions affect systemic metabolism, retinal structure/ function in APOE3-knock-in (KI, neutral for AD) and APOE4-KI mice. Humanized APOE3 and APOE4-KI mice received either a control diet (CD) or a Western diet (WD) for 2, 6, or 12 months. Body weight, glucose metabolism, lipid profiles, retinal structure, function, vasculature, visual performance, and inflammatory markers were analyzed. WD induced early glucose intolerance in APOE4 mice (2 months); APOE3 mice showed impairment only after prolonged exposure (6-12 months). Notably, WD-fed APOE3 mice exhibited more pronounced hyperlipidemia than APOE4 mice. APOE4 CD mice displayed early retinal thinning (6 months), while APOE4 WD mice initially exhibited retinal swelling, followed by degeneration (12 months). WD exacerbated retinal vascular dysfunction in APOE4 mice, with increased tortuosity and reduced vascular area. Elevated Il1b expression in WD-fed APOE4 mice confirmed inflammation-associated retinal dysfunction. APOE4 mice showed heightened vulnerability to diet, with WD worsening metabolic, retinal, and vascular impairments. While CD improved glucose metabolism, it did not prevent retinal dysfunction. These findings underscore genotype-specific dietary strategies to mitigate APOE4-associated risks.

neuroscience↗

bioRxiv2025

M&uumlller glial Kir4.1 channel Dysfunction in APOE4-KI model of Alzheimer's disease

Alzheimers disease (AD), particularly late-onset AD (LOAD), affects millions worldwide, with the apolipoprotein {varepsilon}4 (APOE4) allele being a significant genetic risk factor. Retinal abnormalities are a hallmark of LOAD, and our recent study demonstrated significant age-related retinal impairments in APOE4-knock-in (KI) mice, highlighting that retinal impairments occur before the onset of cognitive decline in these mice. Muller cells (MCs), key retinal glia, are vital for retinal health, and their dysfunction may contribute to retinal impairments seen in AD. MCs maintain potassium balance via specialized inwardly rectifying K+ channels 4.1 (Kir4.1). This study posits that Kir4.1 channels will be impaired in APOE4-KI, resulting in MC dysfunction. Additionally, we demonstrate that MC dysfunction in APOE4-KI stems from alterations in mitochondrial dynamics and oxidative stress. Kir4.1 expression and function were studied using immunofluorescence and through the whole-cell voltage clamp, respectively. In parallel, rat Muller cells (rMC-1) were used to create an in vitro model for further mechanistic studies. Mitoquinol (MitoQ) was used to evaluate its potential to mitigate APOE4-induced deficits. APOE4 retinas and APOE4-transfected rMC-1 significantly reduced Kir4.1 expression, K+ buffering capacity, and increased mitochondrial damage. APOE4-transfected rMC-1 showed reduced mitochondrial membrane potential ({Delta}{Psi}m) and increased mitochondrial reactive oxygen species (ROS). MitoQ treatment significantly reduced mitochondrial ROS and restored Kir4.1 expression in APOE4-expressing cells. Our results demonstrate that APOE4 causes mitochondrial dysfunction and MC impairment, which may contribute to retinal pathology in AD. MitoQ restored mitochondrial health and Kir4.1 expression in APOE4-expressing rMC-1, suggesting targeting mitochondria may offer a promising therapeutic strategy for AD. Main PointsO_LIAPOE4 impairs Muller cell health by reducing Kir4.1 expression and buffering. C_LIO_LIAPOE4 causes mitochondrial dysfunction with decreased {Delta}{Psi}m and increased ROS. C_LIO_LIMitoQ restores Kir4.1 expression and reduces ROS in APOE4-transfected cells. C_LI

neuroscience↗

bioRxiv2025

BMAL1 Overexpression in Suprachiasmatic Nucleus Protects from Retinal Neurovascular Deficits in Diabetes

The suprachiasmatic nucleus (SCN) regulates circadian rhythms and influences physiological and behavioral processes. Disruptions in circadian rhythms (CRD) are observed in type 2 diabetes (T2D), and importantly, CRD acts as an independent risk factor for T2D and its associated complications. BMAL1, a circadian clock gene, is vital for sustaining an optimal circadian rhythm and physiological function. However, the therapeutic potential of BMAL1 overexpression in the SCN to rectify the neurovascular deficits of T2D has yet to be investigated. In this study, db/db mice, a well-established model of T2D exhibiting arrhythmic behavior and the complications of diabetes, were injected stereotaxically with AAV8-Bmal1 or a control virus in the SCN to evaluate the protective effects of correcting the central clock on neurovascular deficits. Given the complex neurovascular network and the eyes unique accessibility as a transparent system, ocular complications were selected as a model to examine the neuronal functional, behavioral, and vascular benefits of correcting the central clock. BMAL1 overexpression normalized the circadian rhythms, as demonstrated by improvements in the free-running period. The retinal neuronal function improved on electroretinogram, along with optomotor behavior and visual acuity enhancements. Retinal vascular deficits were also significantly reduced. Notably, our approach helped decrease fat content in genetically predisposed obese animals. Since the SCN is known to regulate hepatic glucose production via sympathetic mechanisms, glycemic control, and pyruvate tolerance tests were conducted. Systemically, we observed improved glucose homeostasis in BMAL1-overexpressing mice alongside a substantial reduction in hepatic gluconeogenesis. BMAL1 overexpression lowered plasma norepinephrine and liver TH levels, indicating a protective regulation of adrenergic signaling. Thus, this study underscores the therapeutic potential of targeting circadian clock genes like BMAL1 in the SCN to alleviate metabolic and neurovascular deficits associated with T2D. Our research offers a compelling framework for integrating circadian rhythms into managing diabetes and its complications. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/636648v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@109f3c5org.highwire.dtl.DTLVardef@6325b7org.highwire.dtl.DTLVardef@14121fdorg.highwire.dtl.DTLVardef@11e90aa_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Transcriptomic Profile of Lin-Sca1+c-kit (LSK) cells in db/db mice with long-standing diabetes

The Lin-Sca1+c-Kit+ (LSK) fraction comprises multipotent hematopoietic stem cells (HSCs), vital to tissue homeostasis and vascular repair. While HSC homeostasis is impaired in diabetes, it is not known how chronic (>6 months) type 2 diabetes (T2D) alters the HSC transcriptome. Herein, we assessed the transcriptomic signature of HSCs in db/db mice employing mRNA and miRNA sequencing. We uncovered 2076 mRNAs and 35 miRNAs differentially expressed in db/db mice, including two novel miRNAs previously unreported in T2D. Further analysis of these transcripts showed a molecular shift with an increase in the pro-inflammatory cytokines and a decrease in anti-inflammatory cytokine expression. Also, pathway mapping unveiled inflammation and angiogenesis as one of the top pathways. These effects were reflected in bone marrow mobilopathy, retinal microglial inflammation, and neurovascular deficits in db/db mice. In conclusion, our study highlights that chronic diabetes alters HSCs at the transcriptomic level, thus potentially contributing to overall homeostasis and neurovascular deficits of diabetes, such as diabetic retinopathy. HighlightsO_LIBone marrow mobilopathy with long-standing diabetes C_LIO_LISwitch in LSK transcriptomic profile towards inflammation and angiogenesis C_LIO_LIDiscovered 35 miRNAs, including two novel miRNAs, miR-3968 and miR-1971 C_LIO_LILSK dysfunction reflected in inflammation and neurovascular deficits of the retina C_LI

cell biology↗

bioRxiv2023

Peanut Shell Carbon Nanocellulose Preparation, Analysis and Plausible Role in Regenerative Medicine Using Mesenchymal Stem Cell Line C3H10t1/2

Peanut Shell is a major agro industry waste. Cellulose, the most abundant crystalline component of naturally porous peanut shell biomass. Nanomaterial science has actively used peanut shell as a source of nanocellulose. However, there are few reports on the biocompatibility of cellulose nanocrystal based nanocomposites from agro on mesenchymal cell lines. To evaluate how mesenchymal stem cells behave onto this scaffold in vitro, cellulose nanocrystals (CNCs) made from peanut shells were combined with polyvinyl alcohol (PVA) to create tissue engineering scaffolds. SEM images illustrated that for PVA/CNC nanocomposites and clean PVA respectively, increasing the CNC concentration was accompanied with pore size enlargement. The nanocomposites three-dimensional porous structure conveyed uneven and intertwined pore structures in additionto the pore distribution. The highest relative crystallinity was observed at 10 wt% of CNCs, according to X-ray diffraction, which also showed that the relative crystallinity of the PVA with 0 and 5 wt% of CNCs was lower than that of neat PVA. In order to confirm the modifications in chemical functional groups, Fourier transform infrared spectroscopy was utilized. The non-cytotoxicity of PVA/CNC_10% was measured for cell viability during an in vitro cytotoxicity test. Additionally, the acquired PVA/biocompatibility CNCs with the Murine Mesenchymal cell line (C 3H 10T 1/2) demonstrated good cell spreading and adherence to the material surfaces. These results suggest that future research into the in vitro integration of mesenchymal cells with a PVA/CNC scaffold can prove to be a promising candidate for regenerative purposes.

bioengineering↗

bioRxiv2021

Mucin-mimetic action of capsaicin improves high fat diet-induced gut barrier dysfunction in mice colon

The gut barrier - including tight junction proteins and mucus layers, is the first line of defense against physical, chemical, or pathogenic incursions. This barrier is compromised in various health disorders. Capsaicin, a dietary agonist of Transient receptor potential vanilloid 1 (TRPV1) channel, is reported to alleviate the complications of obesity. While its mode of action is well established to enhance energy expenditure, metabolism and prevent dysbiosis, the more local effects on the host gut - particularly the gut barrier and mucus system remain elusive. We employed a diet-induced obesity model to investigate the effect of capsaicin on the gut barrier and mucus production and to understand the involvement of mucus, bacteria, and TRPV1 in these phenomena. Mucin feeding reflected most of the effects produced by capsaicin, indicating that mucus modulation by capsaicin plays a crucial role in its anti-obesity effects. Capsaicin, bacteria and the host mucus system seem to act in a cyclic cascade involving TRPV1, which can be activated by capsaicin and various bacteria. These findings provide new insight into the role of TRPV1 in maintaining a healthy gut environment. HIGHLIGHTSO_LIExogenous mucin feeding produced anti-obesity effects similar to capsaicin in mice. C_LIO_LIMucin and capsaicin improved TJP expression, intestinal permeability and gut microbial diversity. C_LIO_LICapsaicin modulated bacterial diversity in vitro, independently of the host. C_LIO_LIProbiotic bacteria and butyrate activated TRPV1 in transfected HEK cells. C_LIO_LIAnti-obesity action of capsaicin is not exclusive to TRPV1 agonism. C_LIO_LICapsaicins action as colonic mucus secretagogue - plays a crucial part in its anti-obesity benefits. C_LI

pharmacology and toxicology↗

bioRxiv2021

Proximity-dependent biotinylation to elucidate the interactome of TNK2 non-receptor tyrosine kinase

Non-receptor tyrosine kinases represent an important class of signaling molecules which are involved in driving diverse cellular pathways. Although, the large majority have been well-studied in terms of their protein-binding partners, the interactomes of some of the key non-receptor tyrosine kinases such as TNK2 (also known as activated Cdc42-associated kinase 1 or ACK1) have not been systematically investigated. Aberrant expression and hyperphosphorylation of TNK2 has been implicated in a number of cancers. However, the exact proteins and cellular events that mediate phenotypic changes downstream of TNK2 are unclear. Biological systems that employ proximity-dependent biotinylation methods, such as BioID, are being increasingly used to map protein-protein interactions as they provide increased sensitivity in discovering interaction partners. In this study, we employed BioID coupled to the biotinylation site identification technology (BioSITe) method that we recently developed to perform molecular mapping of intracellular proteins associated with TNK2. We also employed stable isotope labeling with amino acids in cell culture (SILAC) to quantitatively explore the interactome of TNK2. By performing a controlled comparative analysis between full-length TNK2 and its truncated counterpart, we were not only able to confidently identify site-level biotinylation of previously well-established TNK2 binders and substrates such as NCK1, NCK2, CTTN, STAT3, but also discover several novel TNK2 interacting partners. We validated TNK2 interaction with one of the novel TNK2 interacting protein, clathrin interactor 1 (CLINT1), using immunoblot analysis. Overall, this work reveals the power of the BioSITe method coupled to BioID and highlights several molecules that warrant further exploration to assess their functional significance in TNK2-mediated signaling.

cancer biology↗

bioRxiv2020

Role of TRPV1 in colonic mucin production and gut microbiota profile

PURPOSEThis study focuses on exploring the role of sensory cation channel Transient Receptor Potential channel subfamily Vanilloid 1 (TRPV1) in gut health, specifically mucus secretion and microflora profile in gut. METHODS AND RESULTSWe employed resiniferatoxin (ultrapotent TRPV1 agonist) induced chemo-denervation model in rats and studied the effects of TRPV1 ablation on gut mucus secretion patterns. Histological and transcriptional analysis showed substantial decrease in mucus production as well as in expression of genes involved in goblet cells differentiation, mucin production and glycosylation. 16S metagenome analysis revealed changes in abundance of various gut bacteria, including decrease in beneficial bacteria like Lactobacillus spp and Clostridia spp. Also, TRPV1 ablation significantly decreased the levels of short chain fatty acids, i.e. acetate and butyrate. CONCLUSIONThe present study provides first evidence that systemic TRPV1 ablation leads to impairment in mucus secretion and causes dysbiosis in gut. Further, it suggests to address mucin production and gut microbiota related adverse effects during the development of TRPV1 antagonism/ablation-based therapeutic and preventive strategies.

physiology↗