Browsing by Author "Kshirsagar, Sudhir (TTUHSC)"
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Item Amino acid transporter SLC38A5 is a tumor promoter and a novel therapeutic target for pancreatic cancer(2023) Sniegowski, Tyler (TTUHSC); Rajasekaran, Devaraja (TTUHSC); Sennoune, Souad R. (TTUHSC); Sunitha, Sukumaran (TTU); Chen, Fang (TTU); Fokar, Mohamed (TTU); Kshirsagar, Sudhir (TTUHSC); Reddy, P. Hemachandra (TTUHSC); Korac, Ksenija (TTUHSC); Mahmud Syed, Mosharaf (TTUHSC); Sharker, Tanima (TTUHSC); Ganapathy, Vadivel (TTUHSC); Bhutia, Yangzom D. (TTUHSC)Pancreatic ductal adenocarcinoma (PDAC) cells have a great demand for nutrients in the form of sugars, amino acids, and lipids. Particularly, amino acids are critical for cancer growth and, as intermediates, connect glucose, lipid and nucleotide metabolism. PDAC cells meet these requirements by upregulating selective amino acid transporters. Here we show that SLC38A5 (SN2/SNAT5), a neutral amino acid transporter is highly upregulated and functional in PDAC cells. Using CRISPR/Cas9-mediated knockout of SLC38A5, we show its tumor promoting role in an in vitro cell line model as well as in a subcutaneous xenograft mouse model. Using metabolomics and RNA sequencing, we show significant reduction in many amino acid substrates of SLC38A5 as well as OXPHOS inactivation in response to SLC38A5 deletion. Experimental validation demonstrates inhibition of mTORC1, glycolysis and mitochondrial respiration in KO cells, suggesting a serious metabolic crisis associated with SLC38A5 deletion. Since many SLC38A5 substrates are activators of mTORC1 as well as TCA cycle intermediates/precursors, we speculate amino acid insufficiency as a possible link between SLC38A5 deletion and inactivation of mTORC1, glycolysis and mitochondrial respiration, and the underlying mechanism for PDAC attenuation. Overall, we show that SLC38A5 promotes PDAC, thereby identifying a novel, hitherto unknown, therapeutic target for PDAC.Item Early Cellular, Molecular, Morphological and Behavioral Changes in the Humanized Amyloid-Beta-Knock-In Mouse Model of Late-Onset Alzheimer’s Disease(2022) Kshirsagar, Sudhir (TTUHSC); Alvir, Rainier Vladlen (TTUHSC); Hindle, Ashly (TTUHSC); Kumar, Subodh (TTUHSC); Vijayan, Murali (TTUHSC); Pradeepkiran, Jangampalli Adi (TTUHSC); Reddy, Arubala (TTU); Ramasubramanian, Bhagavathi (TTUHSC); Reddy, P. Hemachandra (TTUHSC)The purpose of our study is to investigate early cellular, molecular, morphological and behavioral changes in humanized amyloid-beta-knock-in (hAbKI) mice. Using seven-month-old homozygous hAbKI mice, we studied behavioral phenotype parameters, including spatial learning and memory (Morris Water Maze), locomotor activity (open field), working memory (Y-maze) and motor coordination (rotarod); mRNA abundance, protein levels, soluble amyloid-beta 40 and 42 levels and regional immunoreactivities of key markers of mitochondrial dynamics, mitochondrial biogenesis, synaptic health, mitophagy and autophagy; mitochondrial function and using transmission electron microscopy & Golgi–Cox staining, we assessed mitochondrial morphology and dendritic spines. Our extensive behavioral analysis revealed that seven-month-old hAbKI mice showed impairments in motor coordination, reduced locomotor and exploration activities, impairments in working memory and spatial learning and memory. Our mRNA and protein analyses revealed the increased expression of mitochondrial-fission genes and reduced expression of mitochondrial-fusion, mitochondrial-biogenesis, synaptic, autophagy and mitophagy genes in seven-month-old hAbKI mice. An immunofluorescence analysis revealed altered immunoreactivities and agreed with the immunoblot results. Transmission-electron-microscopy data revealed increased mitochondrial fragmentation and reduced mitochondrial length in both hippocampal and cortical tissues of seven-month-old hAbKI mice and mitochondrial function defective. A Golgi–Cox-staining analysis revealed reduced dendritic spines in both cerebral cortices and hippocampi of hAbKI mice. Soluble amyloid-beta (1–40 and 1–42) were detected in three-month-old hAbKI mice and progressively increased in seven-month-old mice. These observations suggest that the human amyloid-beta peptide is sufficient to cause behavioral, mitochondrial, synaptic and ultrastructural changes in seven-month-old hAbKI mice. Our study findings also suggest that hAbKI mice might serve as a model for preclinical studies of preventive therapies.Item Is Effective Recruitment Strategy Critical to Assess Brain Cognitive Function of Super Agers in Rural West Texas(2024) Brownell, Malcolm (TTUHSC); Sehar, Ujala (TTUHSC); Kshirsagar, Sudhir (TTUHSC); Reddy, P. Hemachandra (TTUHSC)Our commentary aims to elucidate the importance of participant recruitment strategy in healthy brain aging study, particularly in rural West Texas, where more than 50% of the population are Hispanics and Latinos. The objective of our health aging study is to investigate the possible influence of biological, sociodemographic, and lifestyle factors on the occurrence of chronic diseases and dementia in the aging populations of West Texas. The success of this initiative is, in large part, reliant on high-quality, effective recruitment of participants. To that end, we propose an increase in our strategic recruitment efforts for both healthy, cognitively superior agers as well as those with mild cognitive impairment and patients with Alzheimer's disease in rural west Texas. We discussed, multi-advertising approaches, including ads in the local newspapers, local TV Channels and poster boards in senior centers.Item Rlip Reduction Induces Oxidative Stress and Mitochondrial Dysfunction in Mutant Tau-Expressed Immortalized Hippocampal Neurons: Mechanistic Insights(2023) Reddy, P. Hemachandra (TTUHSC); Kshirsagar, Sudhir (TTUHSC); Bose, Chhanda (TTUHSC); Pradeepkiran, Jangampalli Adi (TTUHSC); Hindle, Ashly (TTUHSC); Singh, Sharda P. (TTUHSC); Reddy, Arubala P. (TTU); Baig, Javaria (TTUHSC)RalBP1 (Rlip) is a stress-activated protein that is believed to play a large role in aging and neurodegenerative diseases such as Alzheimer’s disease (AD) and other tauopathies. The purpose of our study was to understand the role of Rlip in mutant Tau-expressed immortalized hippocampal HT22 cells. In the current study, we used mutant Tau (mTau)-expressed HT22 neurons and HT22 cells transfected with Rlip-cDNA and/or silenced RNA, and studied the cell survival, mitochondrial respiration, mitochondrial function, immunoblotting, and immunofluorescence analysis of synaptic and mitophagy proteins and the colocalization of Rlip and mTau proteins. We found Rlip protein levels were reduced in mTau-HT22 cells, Rlip silenced HT22 cells, and mTau + Rlip RNA silenced HT22 cells; on the other hand, increased Rlip levels were observed in Rlip cDNA transfected HT22 cells. We found cell survival was decreased in mTau-HT22 cells and RNA-silenced HT22 cells. However, cell survival was increased in Rlip-overexpressed mTau-HT22 cells. A significantly reduced oxygen consumption rate (OCR) was found in mTau-HT22 cells and in RNA-silenced Rlip-HT22 cells, with an even greater reduction in mTau-HT22 + Rlip RNA-silenced HT22 cells. A significantly increased OCR was found in Rlip-overexpressed HT22 cells and in all groups of cells that overexpress Rlip cDNA. Mitochondrial function was defective in mTau-HT22 cells, RNA silenced Rlip in HT22 cells, and was further defective in mTau-HT22 + Rlip RNA-silenced HT22 cells; however, it was rescued in Rlip overexpressed in all groups of HT22 cells. Synaptic and mitophagy proteins were decreased in mTau-HT22 cells, and further reductions were found in RNA-silenced mTau-HT22 cells. However, these were increased in mTau + Rlip-overexpressed HT22 cells. An increased number of mitochondria and decreased mitochondrial length were found in mTau-HT22 cells. These were rescued in Rlip-overexpressed mTau-HT22 cells. These observations strongly suggest that Rlip deficiency causes oxidative stress/mitochondrial dysfunction and Rlip overexpression reverses these defects. Overall, our findings revealed that Rlip is a promising new target for aging, AD, and other tauopathies/neurological diseases.