Biology subjects

Kolandaivelu, S.

Publications and source records attributed to Kolandaivelu, S..

5 recordsLinked to original sources

bioRxiv2026

Dietary Sodium Deprivation Remodels the Serum Lipidome and Reveals Systemic Metabolic Adaptation in Rats

BackgroundDietary sodium restriction is a common nutritional and physiological challenge that activates electrolyte-conserving endocrine pathways, but its impact on systemic lipid metabolism remains incompletely defined. We examined whether short-term dietary sodium deprivation alters the circulating lipidome and identifies lipid signatures of metabolic adaptation. MethodsMale Sprague-Dawley rats were maintained on sodium-sufficient (NaS) or sodium-deprived (NaD) diets for 7 days (n=3 per group). Serum lipids were profiled by untargeted LC-MS/MS in positive and negative ion modes. Lipidomic differences were evaluated using class-level and species-level analyses, principal component analysis, volcano plots, heatmaps, and pathway-oriented interpretation. ResultsNaD rats exhibited a distinct serum lipidomic profile compared with NaS controls, indicating global remodeling of circulating lipid composition. Sodium deprivation produced class-specific and species-resolved changes, including selective depletion of subsets of neutral lipid species, prominent wax ester remodeling, increased phosphatidylcholine and lysophosphatidylcholine abundance, and altered acylcarnitine profiles. These signatures are consistent with coordinated changes in lipid storage, membrane phospholipid turnover, and mitochondrial fatty-acid handling. ConclusionsDietary sodium deprivation induces coordinated serum lipidome remodeling in rats, supporting the concept that nutritional electrolyte status can influence systemic lipid metabolism. These exploratory findings identify sodium deprivation as a metabolic stressor linked to neutral lipid mobilization, phospholipid remodeling, and altered mitochondrial substrate handling, and provide a foundation for future mechanistic studies.

physiology↗

bioRxiv2026

Dietary Sodium Restriction Reprograms Gut Microbial Fermentation and Reduces Host Energy Harvest

Diet is a major determinant of gut microbiome structure and function, yet the role of dietary electrolytes--particularly sodium--remains poorly defined. Here, we identify dietary sodium availability as a key regulator of gut microbial fermentation and host energy harvest. Using a controlled sodium-sufficient versus sodium-deprived dietary intervention in rats, we integrated shotgun metagenomic sequencing, functional pathway analysis, targeted short-chain fatty acid (SCFA) quantification, and host physiological phenotyping. Sodium deprivation induced a coordinated restructuring of the gut microbiome, characterized by depletion of classical saccharolytic Firmicutes, including multiple Lactobacillus species, and enrichment of stress-tolerant, metabolically flexible taxa. Functional profiling revealed a shift away from growth-associated metabolic programs toward stress-adaptive and nutrient-scavenging pathways. Consistent with these changes, fecal concentrations of key SCFAs--including acetate, butyrate, hexanoate, and valerate--were significantly reduced, indicating impaired microbial fermentative capacity. These microbiome-level alterations translated into measurable host phenotypes, including reduced cecal mass and attenuated weight gain, consistent with decreased microbial energy harvest. Together, these findings establish a functional link between luminal sodium availability, microbial metabolic efficiency, and host energy balance, extending the framework of diet-microbiome interactions beyond macronutrients to include dietary electrolytes. This work identifies sodium as a previously underappreciated ecological constraint shaping gut microbial metabolism and suggests that modulation of dietary sodium intake may influence host metabolic outcomes through microbiome-mediated mechanisms.

microbiology↗

bioRxiv2024

Aberrant Lipid Accumulation leads to Retinal Pigmental Epithelium Dysfunction and Photoreceptor Degeneration in Prcd-deficient mice

Progressive Rod-Cone Degeneration (PRCD) is an integral membrane protein found in photoreceptor outer segment (OS) disc membranes and its function remains unknown. Mutations in Prcd are implicated in Retinitis pigmentosa (RP) in humans and multiple dog breeds. PRCD-deficient models exhibit decreased levels of cholesterol in the plasma. However, potential changes in the retinal cholesterol remain unexplored. In addition, impaired phagocytosis observed in these animal models points to potential deficits in the retinal pigment epithelium (RPE). Here, using a Prcd-/-murine model we investigated the alterations in the retinal cholesterol levels and impairments in the structural and functional integrity of the RPE. Lipidomic and immunohistochemical analyses show a 5-fold increase in the levels of cholesteryl esters (C.Es) and accumulation of neutral lipids in the PRCD-deficient retina, respectively, indicating alterations in total retinal cholesterol. Longitudinal fundus and spectral domain optical coherence tomography (SD-OCT) examinations showed focal lesions and RPE hyperreflectivity. Strikingly, the RPE of Prcd-/- mice exhibited age-related pathological features such as neutral lipid deposits, lipofuscin accumulation, Bruchs membrane (BrM) thickening and drusenoid focal deposits, mirroring an Age-related Macular Degeneration (AMD)-like phenotype. We propose that the extensive lipofuscin accumulation likely impairs lysosomal function, leading to the defective phagocytosis observed in Prcd-/-mice. Our findings support the dysregulation of retinal cholesterol homeostasis in the absence of PRCD. Further, we demonstrate that progressive photoreceptor degeneration in Prcd-/-mice is accompanied by progressive structural and functional deficits in the RPE, which likely exacerbates vision loss over time.

cell biology↗

bioRxiv2022

Dual Palmitoylation of PRCD, a Photoreceptor-Specific Protein Linked to RP, Alters Protein Stability and Subcellular Localization

Progressive rod-cone degeneration (PRCD) is a photoreceptor outer segment (POS) disc-specific protein essential for maintaining outer segment (OS) structures, while also contributing to rhodopsin packaging densities and distribution in the disc membranes. Previously, we showed PRCD undergoing palmitoylation at the sole cysteine (Cys2), where a mutation is found linked with retinitis pigmentosa (RP) that is crucial for protein stability and trafficking to POS. PRCD has several predicted structural domains with unknown significance, such as the polybasic region (PBR) where an Arg17Cys (R17C) mutation is linked with RP. In this study, we demonstrate that a mutation in the PBR augments additional palmitoyl lipid modification observed through acyl-RAC in the mutant cysteine (R17C). Immunolocalization of transiently expressed R17C protein in hRPE1 cells depicts similar characteristics to wild type (WT); however, a double mutant lacking endogenous palmitoylation at the Cys2 position is comparable to the C2Y protein as both are likely aggregated and mislocalized in the mitochondria. Subretinal injection of C2Y, R17C, and R17C/C2Y mutants followed by electroporation in murine retina exhibit mislocalization in the inner segment compared to WT PRCD. Our results in the R17C mutant show palmitoylation transpires at two different locations. Despite being dually palmitoylated and demonstrating membrane association, the mutation in the PBR affects protein stability and trafficking to the OS. Moreover, palmitoylation within the PBR alone does not compensate for protein stability or trafficking, revealing the PBR domain is indispensable and any defects likely lead to dysregulation of PRCD protein associated with blinding diseases.

biochemistry↗

bioRxiv2021

NMNAT1 facilitates energy metabolism and gene regulation in developing retinal neurons

Despite mounting evidence that the mammalian retina is exceptionally reliant on proper NAD+ homeostasis for health and function, the specific roles of subcellular NAD+ pools in retinal development, maintenance, and disease remain obscure. Here, we show that deletion of the nuclear-localized NAD+ synthase nicotinamide mononucleotide adenylyltransferase-1 (NMNAT1) in the developing murine retina causes early and severe degeneration of photoreceptors and select inner retinal neurons via multiple distinct cell death pathways. This severe phenotype is associated with disruptions to retinal central carbon metabolism, purine nucleotide synthesis, and amino acid pathways. Furthermore, large-scale transcriptomics reveals dysregulation of a collection of photoreceptor and synapse-specific genes in NMNAT1 knockout retinas prior to detectable morphological or metabolic alterations. Collectively, our study reveals previously unrecognized complexity in NMNAT1-associated retinal degeneration and suggests a yet-undescribed role for NMNAT1 in gene regulation during photoreceptor terminal differentiation.

molecular biology↗