Biology subjects

Bhushan, B.

Publications and source records attributed to Bhushan, B..

8 recordsLinked to original sources

bioRxiv2026

Autophagy Cholesterol Axis Remodeling Supports Malignant Progression and Chemoresistance in Glioma

Glioma progression and resistance to temozolomide (TMZ) remain major clinical challenges. Here, we investigated whether dysregulated autophagy and cholesterol metabolism are coordinately remodeled during glioma progression and TMZ resistance. Tissue microarray analysis of astrocytoma and glioblastoma specimens revealed progressive autophagosome accumulation, reflected by increased LC3{beta} puncta, coupled with impaired autophagic flux compared with adjacent normal brain tissue. These alterations intensified with tumor grade and were associated with upregulation of farnesyl diphosphate synthase (FDPS), linking malignant progression to cholesterol pathway remodeling. TMZ-resistant (R) glioblastoma cells exhibited epithelial-to-mesenchymal transition, mitotic quiescence, and mitochondrial remodeling consistent with a therapy-tolerant phenotype. Bioenergetic profiling demonstrated reduced respiratory reserve, diminished ATP-linked respiration, and elevated proton leak, indicating constrained metabolic flexibility. In parallel, impaired autophagy flux was associated with suppression of de novo cholesterol synthesis and transcriptional downregulation of SREBP-2 and LDL-R. Comprehensive lipidomic profiling revealed marked cholesterol metabolic reprogramming in R cells, characterized by accumulation of specific cholesteryl esters, including CE 22:5, CE 22:6, CE 22:4, and CE 20:4, despite reduced cholesterol biosynthesis. Pharmacologic inhibition of the mevalonate pathway with simvastatin significantly altered cholesteryl ester profiles but failed to restore autophagy flux or sensitize R cells to TMZ-induced apoptosis, even under combined TMZ-simvastatin treatment. Lay AbstractAs gliomas progress from astrocytoma to glioblastoma, autophagy becomes dysregulated and cholesterol metabolism is rewired. This coordinated remodeling supports tumor survival, metabolic plasticity, and resistance to temozolomide therapy. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/697885v2_ufig1.gif" ALT="Figure 1000"> View larger version (79K): org.highwire.dtl.DTLVardef@1183dd2org.highwire.dtl.DTLVardef@82e20dorg.highwire.dtl.DTLVardef@c6c8dforg.highwire.dtl.DTLVardef@adb427_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsAutophagy flux blockade intensifies during progression from astrocytoma to glioblastoma Dysregulated autophagy is coupled to altered cholesterol metabolism in malignant gliomas TMZ-resistant glioblastoma cells undergo epithelial-to-mesenchymal transition and mitotic quiescence Resistant cells exhibit constrained bioenergetic capacity and mitochondrial remodeling Impaired autophagy suppresses de novo cholesterol synthesis and lipid recycling Lipidomics reveals accumulation of long-chain cholesteryl esters in TMZ-resistant cells Statin-based cholesterol inhibition fails to resensitize glioblastoma cells to temozolomide

cancer biology↗

bioRxiv2025

Diploid Hepatocytes Resist Acetaminophen-Induced Liver Injury Through Suppressed JNK Signaling

Background & AimsThe liver contains both diploid and polyploid hepatocytes, but their functional differences remain poorly understood. Emerging evidence suggests that each ploidy state contributes to regeneration in an injury-specific manner. We hypothesized that diploid hepatocytes promote healing after acetaminophen (APAP)-induced liver injury. Approach & ResultsTo study ploidy populations in vivo, we utilized mice with a lifelong liver-specific knockout of E2f7/E2f8 (LKO), which are enriched in diploid hepatocytes (>70%) but otherwise normal. Control and LKO mice were treated with APAP (300 or 600 mg/kg), and injury was assessed over 0-96 hours. Although both groups sustained injury, LKO mice showed improved survival, lower serum liver enzyme levels, and reduced necrosis and DNA fragmentation, indicating resistance to APAP-induced injury. To determine if resistance was due to E2f7/E2f8 loss or increased diploidy, we deleted E2f7/E2f8 in adult hepatocytes (HKO), a model that does not alter ploidy. Injury was similar between controls and HKO, ruling out gene deletion as the protective factor. Transcriptomic and protein analyses revealed minimal baseline differences; however, following APAP treatment, LKO livers exhibited reduced JNK activation and less mitochondrial injury. Finally, APAP-treated wild-type hepatocytes exhibited a shift toward lower ploidy, supporting the idea that diploid cells are more resistant to injury. ConclusionsDiploid hepatocytes resist APAP-induced liver injury through reduced JNK activation and mitochondrial damage. These findings highlight hepatocyte ploidy as a key determinant of injury response and suggest a protective role for diploid hepatocytes in promoting liver resilience and regeneration.

genetics↗

bioRxiv2021

Interleukin-6 Drives Key Pathologic Outcomes in Experimental Acetaminophen-induced Liver Failure

Background and AimsIn severe cases of acetaminophen (APAP) overdose, acute liver injury rapidly progresses to acute liver failure (ALF), producing life-threatening complications including, hepatic encephalopathy (HE) and multi-organ failure (MOF). Systemic levels of interleukin-6 (IL-6) and IL-10 are highest in ALF patients with the most severe complications and the poorest prognosis. The mechanistic basis for dysregulation of these cytokines, and their association with outcome in ALF, remain poorly defined. MethodsTo investigate the impact of IL-6 and IL-10 in ALF, we used an experimental setting of failed liver repair after APAP overdose in which a high dose of APAP is administered (i.e., 500-600 mg/kg). Mice were treated with neutralizing antibodies to block IL-6 and IL-10. ResultsIn mice with APAP-induced ALF, high levels of IL-10 reduced monocyte recruitment and trafficking in the liver resulting in impaired clearance of dead cell debris. Kupffer cells in these mice, displayed features of myeloid-derived suppressor cells, including high level expression of IL-10 and PD-L1, which were increased in an IL-6-dependent manner. Similar to ALF patients with HE, cerebral blood flow was reduced in mice with APAP-induced ALF. Remarkably, although IL-6 is hepatoprotective in mice treated with low doses of APAP (i.e., 300 mg/kg), IL-6 neutralization in mice with APAP-induced ALF fully restored cerebral blood flow and reduced mortality. ConclusionCollectively, these studies demonstrate that exaggerated production of IL-6 in APAP-induced ALF triggers immune suppression (i.e., high levels of IL-10 and PD-L1), reduces cerebral blood flow (a feature of hepatic encephalopathy), disrupts liver repair (i.e., failed clearance of dead cells), and increases mortality.

pathology↗

bioRxiv2021

Temporal Dynamics of Neural Processing of Facial Expressions and Emotions

Emotion processing has been a focus of research in psychology and neuroscience for some decades. While the evoked neural markers in human brain activations in response to different emotions have been reported, the temporal dynamics of emotion processing has received less attention. Differences in processing speeds, that depend on emotion type, have not been determined. Furthermore, behavioral studies have found that the right side of the human face expresses emotions more accurately than the left side. Therefore, accounting for both the content of the emotion and the visual angle of presentation from the perspective of the viewer, here we have investigated variability in the discrimination of happy and sad faces when the visual angle of presentation was Positive (right side of the face) compared to Negative (left side of the face). Furthermore, the temporal dynamics involved in processing happy and sad emotions have been compared. Regardless of visual angle, happy emotions were processed faster than sad emotions. However, the evoked response to sad emotions significantly increased in amplitude compared to that for happy emotions, when faces were presented at Positive visual angles only. Source reconstruction from sensor-level ERFs show localized activities in ventral and dorsal stream, including fusiform gyrus, lingual gyrus, putamen and Pre and Post central gyrus. Multivariate pattern analysis (MVPA) confirmed these findings - demonstrating successful decoding of happy and sad emotions only occurred when the facial expression was viewed from a positive visual angle, and that happy emotions were processed faster than sad emotions.

neuroscience↗

bioRxiv2020

Prediction and in vitro silencing of two lipid biosynthetic genes viz. SCD and SREBP1 in chicken using RNA interference

RNA interference is a widely used post transcriptional silencing mechanism for suppressing expression of the target gene. In the current study, five shRNA molecules each against SCD and SREBP1 genes were designed after considering the parameters like secondary structures of shRNA constructs, mRNA target regions, GC content and thermodynamic properties ({Delta}G overall, {Delta}G duplex and {Delta}G break-target) to knockdown their expression. After successful transfection of these shRNA molecules into the chicken embryonic hepatocyte culture, expression of the target genes were monitored by real time PCR. Significant reduction (P<0.05) in the expression of SCD and SREBP1 genes with minimal activation of immune response genes in hepatocytes was observed after transfecting the shRNA molecules into them. The shRNA constructs against SCD gene showed the knock down efficiency ranged from 20.4% to 74.2%. In case of shRNA constructs against SREBP1 gene, they showed knock down efficiency ranging from 26.8% to 95.85%. These results clearly demonstrated the successful down regulation of the gene expression by designed shRNA molecules against both the target genes under in vitro condition. The shRNA2 molecule for SCD gene and the shRNA1 molecule for SREBP1 gene were found as the best among all the shRNA molecules used for silencing the target genes under cell culture system. It is concluded that the shRNA molecules designed against SCD and SREBP1 genes showed potential to silence the expression of these genes under in vitro chicken embryonic hepatocyte cell culture system.

molecular biology↗

bioRxiv2020

Genome-wide SNP data unravel the ancestry and signatures of divergent selection in Ghurrah pigs of India

The evolution and domestication of pigs is a complex and ongoing process. Despite its rich biodiversity and proximity to the geographical origins of Sus scrofa domesticus, the place of Indian pigs in the global phylogeny is unclear. Using microarray-derived (porcine 60K SNP chip) genotypes of 11 Ghurrah pigs from North-Western India and a public dataset comprising 2113 pigs of 146 breeds, we determined the genomic ancestry of Ghurrah pigs and compared their genetic constitution to European and Asian breeds to ascertain signatures of divergent selection. Results showed that Ghurrah pigs contain genes of Asian and European ancestry with signs of inter-species introgression. Using Admixture LD - decay statistics, the European admixture event was dated to the recent past, coinciding with the start of cross-breeding efforts in India. The complex Asian ancestry pattern of the breed resembled that of wild boars of South - Central China and Thailand, possibly suggesting introgression from an Indian wild boar relative. FST and XP - EHH comparisons with Asian breeds highlighted divergent selection in genomic regions associated with odontogenesis and skeletal muscle development. Comparisons with European commercial breeds revealed that genomic regions governing olfaction and response to sensory stimulation were under selection in Ghurrah pigs. QTL for meat and carcass traits also showed divergent selection between European breeds and Ghurrah pigs. Our results present the first genomic characterization of an Indian pig breed using dense microarray-derived genotypes and highlight the importance of further genomic characterization of Indian domestic and wild pigs.

genomics↗

bioRxiv2020

Cholesterol rich, highly phase separated, naked mole-rat brain lipids are exquisitely sensitive to amyloid induced membrane damage

Naked mole-rats are extraordinarily long-lived rodents that do not develop age-related neurodegenerative diseases. Remarkably, they do not accumulate amyloid plaques, even though their brains contain high concentrations of amyloid beta peptide, even from a young age Therefore, these animals offer an opportunity to investigate mechanisms of resistance against the neurotoxicity of amyloid beta aggregation. Working in this direction, here we examine the composition, phase behaviour, and amyloid beta interactions of naked mole-rat brain lipids. Relative to mouse, naked mole-rat brain lipids are rich in cholesterol and contain sphingomyelin in lower amounts and of shorter chain lengths. Proteins associated with metabolism of ceramides, sphingomyelin and ceramide receptor activity were also found to be decreased in naked mole-rat brain lysates. Correspondingly, we find that naked mole-rat brain lipid membranes exhibit a high degree of phase separation, with the liquid ordered phase occupying up to 80% of the supported lipid bilayer. These observations are consistent with the membrane pacemaker hypothesis of ageing, according to which long-living species have lipid membranes particularly resistant to oxidative damage. However, we found that exposure to amyloid beta disrupts the naked mole-rat brain lipid membranes while those formed from mouse brain lipids exhibit small, well-defined footprints, whereby the amyloid beta penetrates deeply into the lipid membranes. These results suggest that in naked mole-rats the lipid composition of cell membranes may offer neuroprotection through resistance to oxidative processes rather than through mechanical effects.

biophysics↗

bioRxiv2018

Naked mole rat hyaluronan - an extreme folding biopolymer

Hyaluronan (HA) is a key component of the extracellular matrix. Given the fundamental role of HA in the cancer resistance of the naked mole-rat (NMR), we undertook to explore the structural and soft matter properties of this species-specific variant, a necessary step for its development as a biomaterial. We examined HA extracted from NMR brain, lung, and skin, as well as that isolated from the medium of immortalised cells. In common with mouse HA, NMR HA forms a range of assemblies corresponding to a wide distribution of molecular weights. However, unique to the NMR, are highly folded structures, whose characteristic morphology is dependent on the tissue type. Skin HA forms tightly packed assemblies that have spring-like mechanical properties in addition to a strong affinity for water. Brain HA forms three dimensional folded structures similar to the macroscopic appearance of the gyri and sulci of the human brain. Lung HA forms an impenetrable mesh of interwoven folds in a morphology that can only be described as resembling a snowman. Unlike HA that is commercially available, NMR HA readily forms robust gels without the need for chemical cross-linking contrasting. NMR HA gels sharply transition from viscoelastic to elastic like properties upon dehydration or repeated loading. In addition, NMR HA can form ordered thin films with an underlying semi-crystalline structure. Given the role of HA in maintaining hydration in the skin it is plausible that the folded structures contribute to both the elasticity and youthfulness of NMR skin. It is also possible that such densely folded materials could present a considerable barrier to cell invasion throughout the tissues, a useful characteristic for a biomaterial.

biophysics↗