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Lietzke AC, Bealer E, Crumley K, King J, Stendahl AM, Zhu J, Pearson GL, Levi-D'Ancona E, Henry-Kanarek B, Reck EC, Arnipalli M, Sidarala V, Walker EM, Pennathur S, Madsen JGS, Shea LD, Soleimanpour SA. Limitations in mitochondrial programming restrain the differentiation and maturation of human stem cell-derived β cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.26.605318. [PMID: 39211191 PMCID: PMC11361182 DOI: 10.1101/2024.07.26.605318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Pluripotent stem cell (SC)-derived islets offer hope as a renewable source for β cell replacement for type 1 diabetes (T1D), yet functional and metabolic immaturity may limit their long-term therapeutic potential. Here, we show that limitations in mitochondrial transcriptional programming impede the formation and maturation of SC-derived β (SC-β) cells. Utilizing transcriptomic profiling, assessments of chromatin accessibility, mitochondrial phenotyping, and lipidomics analyses, we observed that SC-β cells exhibit reduced oxidative and mitochondrial fatty acid metabolism compared to primary human islets that are related to limitations in key mitochondrial transcriptional networks. Surprisingly, we found that reductions in glucose- stimulated mitochondrial respiration in SC-islets were not associated with alterations in mitochondrial mass, structure, or genome integrity. In contrast, SC-islets show limited expression of targets of PPARIZ and PPARγ, which regulate mitochondrial programming, yet whose functions in β cell differentiation are unknown. Importantly, treatment with WY14643, a potent PPARIZ agonist, induced expression of mitochondrial targets, improved insulin secretion, and increased the formation and maturation of SC-β cells both in vitro and following transplantation. Thus, mitochondrial programming promotes the differentiation and maturation of SC-β cells and may be a promising target to improve β cell replacement efforts for T1D.
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Goswami MT, Weh E, Subramanya S, Weh KM, Durumutla HB, Hager H, Miller N, Chaudhury S, Andren A, Sajjakulnukit P, Besirli CG, Lyssiotis CA, Wubben TJ. Glutamine catabolism supports amino acid biosynthesis and suppresses the integrated stress response to promote photoreceptor survival. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.26.582525. [PMID: 38586045 PMCID: PMC10996599 DOI: 10.1101/2024.03.26.582525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Photoreceptor loss results in vision loss in many blinding diseases, and metabolic dysfunction underlies photoreceptor degeneration. So, exploiting photoreceptor metabolism is an attractive strategy to prevent vision loss. Yet, the metabolic pathways that maintain photoreceptor health remain largely unknown. Here, we investigated the dependence of photoreceptors on Gln catabolism. Gln is converted to glutamate via glutaminase (GLS), so mice lacking GLS in rod photoreceptors were generated to inhibit Gln catabolism. Loss of GLS produced rapid rod photoreceptor degeneration. In vivo metabolomic methodologies and metabolic supplementation identified Gln catabolism as critical for glutamate and aspartate biosynthesis. Concordant with this amino acid deprivation, the integrated stress response (ISR) was activated with protein synthesis attenuation, and inhibiting the ISR delayed photoreceptor loss. Furthermore, supplementing asparagine, which is synthesized from aspartate, delayed photoreceptor degeneration. Hence, Gln catabolism is integral to photoreceptor health, and these data reveal a novel metabolic axis in these metabolically-demanding neurons.
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Affiliation(s)
- Moloy T. Goswami
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Eric Weh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Shubha Subramanya
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Katherine M. Weh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Hima Bindu Durumutla
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
- Molecular and Developmental Biology Graduate Program, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Heather Hager
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Nicholas Miller
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Sraboni Chaudhury
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Anthony Andren
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109
| | - Peter Sajjakulnukit
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109
| | - Cagri G. Besirli
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
| | - Costas A. Lyssiotis
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of Michigan, Ann Arbor, MI 48109
- Rogel Cancer Center, University of Michigan, Ann Arbor, MI 48109
| | - Thomas J. Wubben
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105
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Li J, Zhu J, Deng Y, Reck EC, Walker EM, Sidarala V, Hubers DL, Pasmooij MB, Shin CS, Bandesh K, Motakis E, Nargund S, Kursawe R, Basrur V, Nesvizhskii AI, Stitzel ML, Chan DC, Soleimanpour SA. LONP1 regulation of mitochondrial protein folding provides insight into beta cell failure in type 2 diabetes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.03.597215. [PMID: 38895283 PMCID: PMC11185607 DOI: 10.1101/2024.06.03.597215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Proteotoxicity is a contributor to the development of type 2 diabetes (T2D), but it is unknown whether protein misfolding in T2D is generalized or has special features. Here, we report a robust accumulation of misfolded proteins within the mitochondria of human pancreatic islets in T2D and elucidate its impact on β cell viability. Surprisingly, quantitative proteomics studies of protein aggregates reveal that human islets from donors with T2D have a signature more closely resembling mitochondrial rather than ER protein misfolding. The matrix protease LonP1 and its chaperone partner mtHSP70 were among the proteins enriched in protein aggregates. Deletion of LONP1 in mice yields mitochondrial protein misfolding and reduced respiratory function, ultimately leading to β cell apoptosis and hyperglycemia. Intriguingly, LONP1 gain of function ameliorates mitochondrial protein misfolding and restores human β cell survival following glucolipotoxicity via a protease-independent effect requiring LONP1-mtHSP70 chaperone activity. Thus, LONP1 promotes β cell survival and prevents hyperglycemia by facilitating mitochondrial protein folding. These observations may open novel insights into the nature of impaired proteostasis on β cell loss in the pathogenesis of T2D that could be considered as future therapeutic targets.
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Grumbine MK, Kamat V, Bao K, Crupi T, Mokate K, Lim R, Chao JR, Robbings BM, Hass DT, Hurley JB, Sweet IR. Maintaining and Assessing Various Tissue and Cell Types of the Eye Using a Novel Pumpless Fluidics System. J Vis Exp 2023:10.3791/65399. [PMID: 37522735 PMCID: PMC10791547 DOI: 10.3791/65399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023] Open
Abstract
Many in vitro models used to investigate tissue function and cell biology require a flow of media to provide adequate oxygenation and optimal cell conditions required for the maintenance of function and viability. Toward this end, we have developed a multi-channel flow culture system to maintain tissue and cells in culture and continuously assess function and viability by either in-line sensors and/or collection of outflow fractions. The system combines 8-channel, continuous optical sensing of oxygen consumption rate with a built-in fraction collector to simultaneously measure production rates of metabolites and hormone secretion. Although it is able to maintain and assess a wide range of tissue and cell models, including islets, muscle, and hypothalamus, here we describe its operating principles and the experimental preparations/protocols that we have used to investigate bioenergetic regulation of isolated mouse retina, mouse retinal pigment epithelium (RPE)-choroid-sclera, and cultured human RPE cells. Innovations in the design of the system, such as pumpless fluid flow, have produced a greatly simplified operation of a multi-channel flow system. Videos and images are shown that illustrate how to assemble, prepare the instrument for an experiment, and load the different tissue/cell models into the perifusion chambers. In addition, guidelines for selecting conditions for protocol- and tissue-specific experiments are delineated and discussed, including setting the correct flow rate to tissue ratio to obtain consistent and stable culture conditions and accurate determinations of consumption and production rates. The combination of optimal tissue maintenance and real-time assessment of multiple parameters yields highly informative data sets that will have great utility for research in the physiology of the eye and drug discovery for the treatment of impaired vision.
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Affiliation(s)
| | - Varun Kamat
- UW Medicine Diabetes Institute, University of Washington
| | | | | | - Kedar Mokate
- UW Medicine Diabetes Institute, University of Washington
| | - Rayne Lim
- Department of Ophthalmology, University of Washington
| | | | | | - Daniel T Hass
- Department of Biochemistry, University of Washington
| | | | - Ian R Sweet
- EnTox Sciences, Inc; UW Medicine Diabetes Institute, University of Washington;
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