Browsing by Author "Mohallem, Rodrigo"

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    Alkynyl nicotinamides show antileukemic activity in drug-resistant acute myeloid leukemia
    (The American Society for Clinical Investigation, 2024-06-17) Ramdas, Baskar; Dayal, Neetu; Pandey, Ruchi; Larocque, Elizabeth; Kanumuri, Rahul; Pasupuleti, Santhosh Kumar; Liu, Sheng; Kanellopoulou, Chrysi; Chu, Elizabeth Fei Yin; Mohallem, Rodrigo; Virani, Saniya; Chopra, Gaurav; Aryal, Uma K.; Lapidus, Rena; Wan, Jun; Emadi, Ashkan; Haneline, Laura S.; Holtsberg, Frederick W.; Aman, M. Javad; Sintim, Herman O.; Kapur, Reuben; Pediatrics, School of Medicine
    Activating mutations of FLT3 contribute to deregulated hematopoietic stem and progenitor cell (HSC/Ps) growth and survival in patients with acute myeloid leukemia (AML), leading to poor overall survival. AML patients treated with investigational drugs targeting mutant FLT3, including Quizartinib and Crenolanib, develop resistance to these drugs. Development of resistance is largely due to acquisition of cooccurring mutations and activation of additional survival pathways, as well as emergence of additional FLT3 mutations. Despite the high prevalence of FLT3 mutations and their clinical significance in AML, there are few targeted therapeutic options available. We have identified 2 novel nicotinamide-based FLT3 inhibitors (HSN608 and HSN748) that target FLT3 mutations at subnanomolar concentrations and are potently effective against drug-resistant secondary mutations of FLT3. These compounds show antileukemic activity against FLT3ITD in drug-resistant AML, relapsed/refractory AML, and in AML bearing a combination of epigenetic mutations of TET2 along with FLT3ITD. We demonstrate that HSN748 outperformed the FDA-approved FLT3 inhibitor Gilteritinib in terms of inhibitory activity against FLT3ITD in vivo.
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    Proteomic analysis of murine kidney proximal tubule sub-segment derived cell lines reveals preferences in mitochondrial pathway activity
    (Elsevier, 2023) Ferreira, Ricardo Melo; de Almeida, Rita; Culp, Clayton; Witzmann, Frank; Wang, Mu; Kher, Rajesh; Nagami, Glenn T.; Mohallem, Rodrigo; Andolino, Chaylen Jade; Aryal, Uma K.; Eadon, Michael T.; Bacallao, Robert L.; Medicine, School of Medicine
    The proximal tubule (PT) is a nephron segment that is responsible for the majority of solute and water reabsorption in the kidney. Each of its sub-segments have specialized functions; however, little is known about the genes and proteins that determine the oxidative phosphorylation capacity of the PT sub-segments. This information is critical to understanding kidney function and will provide a comprehensive landscape of renal cell adaptations to injury, physiologic stressors, and development. This study analyzed three immortalized murine renal cell lines (PT S1, S2, and S3 segments) for protein content and compared them to a murine fibroblast cell line. All three proximal tubule cell lines generate ATP predominantly by oxidative phosphorylation while the fibroblast cell line is glycolytic. The proteomic data demonstrates that the most significant difference in proteomic signatures between the cell lines are proteins known to be localized in the nucleus followed by mitochondrial proteins. Mitochondrial metabolic substrate utilization assays were performed using the proximal tubule cell lines to determine substrate utilization kinetics thereby providing a physiologic context to the proteomic dataset. This data will allow researchers to study differences in nephron-specific cell lines, between epithelial and fibroblast cells, and between actively respiring cells and glycolytic cells. SIGNIFICANCE: Proteomic analysis of proteins expressed in immortalized murine renal proximal tubule cells was compared to a murine fibroblast cell line proteome. The proximal tubule segment specific cell lines: S1, S2 and S3 are all grown under conditions whereby the cells generate ATP by oxidative phosphorylation while the fibroblast cell line utilizes anaerobic glycolysis for ATP generation. The proteomic studies allow for the following queries: 1) comparisons between the proximal tubule segment specific cell lines, 2) comparisons between polarized epithelia and fibroblasts, 3) comparison between cells employing oxidative phosphorylation versus anaerobic glycolysis and 4) comparisons between cells grown on clear versus opaque membrane supports. The data finds major differences in nuclear protein expression and mitochondrial proteins. This proteomic data set will be an important baseline dataset for investigators who need immortalized renal proximal tubule epithelial cells for their research.
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    Sulfotransferase 1C2 Increases Mitochondrial Respiration by Converting Mitochondrial Membrane Cholesterol to Cholesterol Sulfate
    (American Chemical Society, 2024) Kolb, Alexander J.; Corridon, Peter; Ullah, Mahbub; Pfaffenberger, Zechariah J.; Xu, Wei Min; Winfree, Seth; Sandoval, Ruben H.; Hato, Takeshi; Witzmann, Frank A.; Mohallem, Rodrigo; Franco, Jackeline; Aryal, Uma K.; Atkinson, Simon J.; Basile, David P.; Bacallao, Robert L.; Biology, School of Science
    Hypothesis: In this communication, we test the hypothesis that sulfotransferase 1C2 (SULT1C2, UniProt accession no. Q9WUW8) can modulate mitochondrial respiration by increasing state-III respiration. Methods and results: Using freshly isolated mitochondria, the addition of SULT1C2 and 3-phosphoadenosine 5 phosphosulfate (PAPS) results in an increased maximal respiratory capacity in response to the addition of succinate, ADP, and rotenone. Lipidomics and thin-layer chromatography of mitochondria treated with SULT1C2 and PAPS showed an increase in the level of cholesterol sulfate. Notably, adding cholesterol sulfate at nanomolar concentration to freshly isolated mitochondria also increases maximal respiratory capacity. In vivo studies utilizing gene delivery of SULT1C2 expression plasmids to kidneys result in increased mitochondrial membrane potential and confer resistance to ischemia/reperfusion injury. Mitochondria isolated from gene-transduced kidneys have elevated state-III respiration as compared with controls, thereby recapitulating results obtained with mitochondrial fractions treated with SULT1C2 and PAPS. Conclusion: SULT1C2 increases mitochondrial respiratory capacity by modifying cholesterol, resulting in increased membrane potential and maximal respiratory capacity. This finding uncovers a unique role of SULT1C2 in cellular physiology and extends the role of sulfotransferases in modulating cellular metabolism.