bims-celmim 2026-08-30 papers

bims-celmim

Biomed News

on Cellular and mitochondrial metabolism

Issue of 2026–08–30
fourteen papers selected by
Marc Segarra Mondejar, AINA

Consumption of Fructose by Cultured Primary Rat Astrocytes.
IP3R2-mediated inter-organelle calcium signaling suppresses melanosome degradation.
Lipid-manager autophagy proteins ATG2 and ATG9 regulate extracellular vesicle secretion via amphisome biogenesis and cell lipidome modulation.
Calcium Imaging in H4IIE Liver Cells and Primary Rodent Hepatocytes: A Cost-Effective Protocol for Use With Fura-2 AM Ca2+ Indicator.
Excess glutamine rewires endothelial cell metabolism.
Propionic Acid Remodels Mitochondrial Metabolism in SH-SY5Y Cells.
Prohibitin controls MRS2-Mediated mitochondrial Mg2+ uptake to Shape bioenergetics.
Roles of autophagy in brain homeostasis and disease.
All-optical multimodal mapping of single-cell-type-specific metabolic activities via REDCAT.
Fluorogenic Autophagic Vesicle-Engaging Probe Enables High-Contrast and Homogeneous Imaging of Autophagic Flux in Live Cells.
Mitophagy mitigates mitochondrial DNA-induced activation of cGAS-STING in autoimmune thyroiditis.
Excessive EFHD1-dependent ER-mitochondrial contacts drive a maladaptive antiviral response in metabolic liver disease.
The molecular basis of mitochondrial crista formation by the MIC10 complex.
A 3D human retina model reveals a non-cell-autonomous and non-neuronal mechanism of photoreceptor loss in a lysosomal storage disorder.

Neurochem Res. 2026 Aug 27. pii: 253. [Epub ahead of print]51(5):

Consumption of Fructose by Cultured Primary Rat Astrocytes.

Mariana Mesa-Leal, Ralf Dringen.

  Fructose has recently gained substantial interest in the context of diseases that are connected with sucrose-rich diets. Several studies have shown that astrocytes are able to metabolize fructose to some extent but less efficiently than glucose. To study whether and how fructose can fuel astrocytic energy metabolism, we used cultured primary astrocytes as model. These cells consumed fructose in a time- and concentration-dependent manner that followed apparent Michaelis-Menten type kinetics with a KM value of 2.8 ± 0.9 mM and a VMax value of 325 ± 32 nmol/(mg × h). Although the specific consumption of glucose and the production of lactate from glucose were around 4 times higher than the respective values for fructose, the loss of astrocytic cellular ATP during starvation was prevented by both fructose and glucose with similar concentration dependencies. However, severe differences were observed for fructose- and glucose-fed astrocytes, if the mitochondrial oxidative phosphorylation was impaired. For fructose-treated astrocytes the application of inhibitors of mitochondrial ATP regeneration almost doubled the low basal glycolytic lactate production, but this was insufficient to prevent a rapid and severe loss in cellular ATP content and subsequent cell toxicity. In contrast, for glucose-treated cells a strong upregulation of glycolysis was connected with a slow ATP loss and a delayed onset of toxicity. Although hexokinase in astrocytic cell lysates was found to have a high KM value for fructose (4.4 ± 1.1 mM), hardly any free fructose was found in astrocytic lysates even after exposure to 10 mM fructose, suggesting that not the phosphorylation but rather the uptake of fructose limits astrocytic fructose consumption. The data presented demonstrate that millimolar concentrations of fructose are required to make this hexose a suitable extracellular substrate for astrocytic metabolism and that fructose metabolism provides energy mainly by mitochondrial respiration.

Keywords:  ATP; Astrocytes; Fructose; Glycolysis; Metabolism; Respiration

DOI:  https://doi.org/10.1007/s11064-026-04873-w
PLoS Biol. 2026 Aug 25. 24(8): e3003971

IP3R2-mediated inter-organelle calcium signaling suppresses melanosome degradation.

Suman Saurav, Anuradha Jadon, Rajender K Motiani.

Organelle turnover is fundamental to cellular homeostasis and regulates both physiological processes and pathological outcomes. Skin pigmentation is determined by the balance between melanosome biogenesis and degradation. However, the mechanisms governing melanosome degradation, i.e., melanophagy remain largely unappreciated. Here, we reveal Inositol 1,4,5-trisphosphate receptor 2 (IP3R2) as a selective suppressor of melanophagy. To enable real-time monitoring of melanophagy, we developed and characterized two novel ratiometric live-cell imaging probes. Using a multi-pronged strategy combining live-cell imaging with the probes, biochemical studies, ultrastructural analyses, molecular approaches, and calcium imaging, we demonstrate that IP3R2 suppresses melanophagy. Importantly, in vivo studies in zebrafish model and meta-analysis of human skin microarrays substantiate the physiological relevance of IP3R2 in pigmentation. Mechanistically, IP3R2 depletion impairs mitochondrial Ca2+ uptake, elevates the ADP/ATP ratio and initiates melanophagy. Concurrently, IP3R2 loss enhances ER-lysosome contacts, increases lysosomal Ca2+ levels via TMEM165, and activates TRPML1 and nuclear translocation of TFEB. This in turn transcriptionally induces melanophagy receptor and E3 ligase. Collectively, IP3R2 acts as a critical determinant of melanophagy and a potential therapeutic target for pigmentary disorders and skin malignancies.

DOI: https://doi.org/10.1371/journal.pbio.3003971
Nat Commun. 2026 Jul 22. pii: 8948. [Epub ahead of print]17(1):

Lipid-manager autophagy proteins ATG2 and ATG9 regulate extracellular vesicle secretion via amphisome biogenesis and cell lipidome modulation.

Asmita Singh, Dylan J Johnson, Jeffrey Kuhn, Katina L Johnson, Jason G Williams, Ricardo Vancini, Deloris Sutton, Kedar Sharma, Jadranka Loncarek, Mario J Borgnia, Carlos M Guardia.

Autophagy intersects with endocytic trafficking to regulate extracellular vesicle (EV) biogenesis, but how upstream lipid-handling autophagy proteins influence this crosstalk is unclear. Here we show that the autophagy lipid-supply proteins ATG9A and ATG2A/B restrain small EV (sEV) secretion by promoting amphisome formation and controlling cellular lipid composition. Deletion of ATG9A or ATG2A/B in cells, which abolishes autophagosome biogenesis, causes a RAB27A-dependent increase in secretion of CD63-enriched, smaller sEVs, and accumulation of intraluminal vesicles within multivesicular endosomes. Under lysosomal inhibition, wild-type cells release LC3- and autophagy cargo receptor-positive sEVs, whereas ATG9A- and ATG2A/B-deficient cells, despite hypersecretion of sEVs, fail to load LC3 or canonical cargo receptors, indicating a block in amphisome-mediated export. Proteomics reveals selective depletion of autophagy receptors and ferritinophagy factors and enrichment of RNA-binding proteins and endosomal trafficking regulators in sEVs from ATG9A- and ATG2A/B-deficient cells. Whole-cell lipidomics uncovers extensive rewiring of the lipidome, with accumulation of ceramides and neutral lipids, altered phospholipid balance, and transcriptional remodeling of lipid metabolic enzymes, while neutral sphingomyelinase inhibition normalizes sEV output. These findings identify ATG9A and ATG2A/B as lipid-dependent gatekeepers that couple autophagosome and amphisome formation, regulating membrane partition between degradative autophagy and exosome-mediated secretion.

DOI: https://doi.org/10.1038/s41467-026-75742-x
Bio Protoc. 2026 Aug 20. 16(16): e5783

Calcium Imaging in H4IIE Liver Cells and Primary Rodent Hepatocytes: A Cost-Effective Protocol for Use With Fura-2 AM Ca2+ Indicator.

Lu Fang, Ahmed G K Habib, Marlee D Harris, Alex J Begley, Eunus S Ali.

  Calcium signaling is a universal, versatile process in which ionized or free calcium (Ca2+) acts as a second messenger to regulate various cellular activities, including hormone secretion, contraction, proliferation, gene expression, and apoptosis. Changes in the cytoplasmic free Ca2+ concentration ([Ca2+]cyt) in hepatocytes play a central role in mediating the actions of insulin, glucagon, catecholamines, and other hormones on carbohydrate, lipid, and protein metabolism in the liver. Ratiometric chemical Ca2+ indicators are fluorescent dyes that change their emission or excitation spectrum upon binding to calcium, allowing for precise, quantitative measurements of changes in the intracellular Ca2+ concentration. They enable calibration by calculating the ratio of two fluorescence intensities, correcting for artifacts such as uneven dye loading, photobleaching, and cell volume variations. Fura-2 acetoxymethyl ester (AM) (hereinafter referred to as Fura-2), a ratiometric and sensitive indicator dye, is a popular fluorescent Ca2+ reporter for measuring intracellular calcium. Here, we describe a comprehensive and detailed protocol for Ca2+ imaging of the H4IIE cell line and primary rodent hepatocytes in vitro via the chemical reporter Fura-2, which can also be employed on a wide variety of cell types. Unlike previously published protocols, this protocol addresses the challenge of facilitating the attachment of liver cell lines and primary hepatocytes to glass coverslips for imaging using an inverted fluorescence microscope. Our protocol describes two different loading/labeling strategies for Fura-2 dye: one is cost-effective but requires skillful pipettor handling, and the second one is easy but expensive as it needs a large volume of Krebs-Ringer HEPES (KRH)-Fura-2 solution. If the coverslips are handled properly, the cost-effective coverslip-only loading approach produces similar quality results as the large volume method. Finally, we describe a simple and user-friendly procedure to analyze Ca2+ signals over time using Microsoft Excel's functional equations. Key features • This protocol enables real-time monitoring of intracellular Ca2+ in living hepatocytes. • The method is based on fluorescence microscopy of hepatocytes loaded with Fura-2 fluorescent dye; moreover, the protocol can be extended to other mammalian cell lines. • We used this protocol to monitor the activity of store-operated Ca2+ channels or SERCA pumps, but it could also be extended to other intracellular phenomena. • If the Fura-2 loading strategy and incubation time are followed properly, this protocol produces highly reproducible imaging results.

Keywords:  Calcium signaling; Fura-2 AM; H4IIE liver cells; Hepatocytes; Single-cell imaging; Store-operated Ca2+ entry

DOI:  https://doi.org/10.21769/BioProtoc.5783
Metabolomics. 2026 Aug 22. pii: 143. [Epub ahead of print]22(5):

Excess glutamine rewires endothelial cell metabolism.

Marzyeh Kheradmand, Xinyao Zhou, Funke Okunrinboye, Ganesh Sriram, Alisa Morss Clyne.

INTRODUCTION: Glutamine, the most abundant amino acid in the body, is a key metabolic substrate for endothelial cells. Glutamine supplementation protects against cardiovascular disease in animal models and in humans; however, glutamine in vitro has inconsistent effects on endothelial function. Furthermore, little is known about how altered metabolite concentrations, for example excess glucose in hyperglycemia or excess glutamine in cell culture media, affect endothelial cell metabolism.
OBJECTIVES: The objective of this study was to determine how physiological and supplemented glutamine affect endothelial metabolism in normal and high glucose conditions.
METHODS: Primary human coronary artery endothelial cells were cultured in varied glutamine concentrations and in normal and high glucose. Glutamine uptake and glutamate secretion were measured using a YSI bioanalyzer; oxidative respiration was assessed using a Seahorse Metabolic Analyzer; and glutamine carbon incorporation into the TCA cycle, amino acids, antioxidants, and other pathways was evaluated via liquid chromatography-mass spectrometry.
RESULTS: As extracellular glutamine increased, endothelial cells took up more glutamine, but glutamate secretion saturated above 2 mM glutamine. Excess glutamine was primarily stored intracellularly, although increasing extracellular glutamine concentration did increase oxidative respiration and TCA cycle isotope enrichment. We also observed increased glutamine incorporation into glutathione, UDP-GlcNAc, and amino acids. When total metabolite abundance was examined, intracellular succinate, unsaturated fatty acids, and one-carbon metabolism-related metabolites decreased with increasing glutamine.
CONCLUSION: These findings demonstrate that excess extracellular glutamine reprograms endothelial metabolism, suggesting that glutamine supplementation should be used with caution in cardiovascular therapies and endothelial cell culture.

DOI: https://doi.org/10.1007/s11306-026-02515-4
Biology (Basel). 2026 Aug 18. pii: 1424. [Epub ahead of print]15(16):

Propionic Acid Remodels Mitochondrial Metabolism in SH-SY5Y Cells.

Caitlyn Mahony, Erin Buchanan, Colleen O'Ryan.

  Mitochondrial mechanisms are increasingly implicated in complex neurological conditions, including Autism Spectrum Disorder (ASD). Propionic acid (PPA) is widely used to study mitochondrial dysfunction in preclinical models of ASD. However, the molecular mechanisms that drive PPA-induced neurotoxicity are unresolved. Here, we examined mitochondrial remodeling under PPA-induced stress in neuroblastoma SH-SY5Y cells. PPA systemically altered the transcriptional regulation of mitochondrial dynamics and disrupted canonical proteins involved in mitochondrial fusion (L-OPA1, MFN2), fission (DRP1) and quality control (LC3-II). Confocal microscopy revealed an upregulation of both fission and fusion events and impairments to mitochondrial integrity, connectivity and turnover. Live-cell respirometry demonstrated consequent deficits in both oxidative and glycolytic energy production, while respiratory chain electron flow assays illustrated a shift in TCA cycle flux driven by a remodeling of mitochondrial substrate utilization. This work describes a molecular signature of metabolic stress in the SH-SY5Y system, providing novel insights into the mechanisms and manifestations of PPA-induced neurotoxicity.

Keywords:  autism spectrum disorder; confocal microscopy; inherited metabolic diseases; mitochondrial dysfunction; propionic acidemia; respirometry

DOI:  https://doi.org/10.3390/biology15161424
Cell Rep. 2026 Aug 27. pii: S2211-1247(26)00951-4. [Epub ahead of print]45(9): 117873

Prohibitin controls MRS2-Mediated mitochondrial Mg2+ uptake to Shape bioenergetics.

Soumya Maity, Manigandan Venkatesan, Adhishree Chidambaram, Sukanthathulse Uthayabalan, Louis Tung Faat Lai, Nicholas D Clark, Abhinaya Lakkureddi, Karthik Ramachandran, Kristen Bentz, Ravi Ramalingam, Sanjana Sen, Moeez Akram, Susan T Weintraub, Brij B Singh, David Gius, Joseph A Baur, Arianne L Theiss, Jeffrey Caplan, Doreen Matthies, Peter B Stathopulos, Muniswamy Madesh.

  Mitochondrial magnesium (mMg2+) is essential for cellular metabolism and bioenergetics, yet the mechanisms governing its transport remain poorly understood. Although MRS2 constitutes the pore of the mMg2+ channel, the molecular machinery regulating its function is unknown. Here, unbiased proteomics identified the prohibitin (PHB) complex as a prominent MRS2-interacting partner. Integrated biochemical and functional analyses demonstrate that the conserved coiled-coil domain mediates MRS2 homo-oligomerization, whereas the C-terminal region of MRS2 interacts with PHB1 to promote channel activity. Quantitative calibration of mitochondria-targeted MagFRET sensors revealed maximal mMg2+ uptake (∼15 mM), which was markedly reduced in Phb1-deficient hepatocytes. Complementary loss- and gain-of-function studies establish PHB1 as a positive regulator of MRS2-mediated mMg2+ uptake without affecting MCU-dependent Ca2+ transport. In vivo, hepatic Phb1 deletion attenuated mMg2+ uptake and enhanced cellular bioenergetics. These findings identify PHB1 as an activator of the MRS2, advancing our understanding of mMg2+ uptake machinery and its role in metabolic regulation.

Keywords:  CP: molecular biology; MCU; MRS2; PHB; bioenergetics; calcium; channel; endoplasmic reticulum; magnesium; metabolism; mitochondria; prohibitin; structure

DOI:  https://doi.org/10.1016/j.celrep.2026.117873
Nat Neurosci. 2026 Aug 24.

Roles of autophagy in brain homeostasis and disease.

Henry Kim, Edward S Wickstead, Xiaoting Zhou, Insup Choi, Zhenyu Yue.

Macroautophagy (autophagy) is a lysosome-dependent degradative pathway that encapsulates proteins and organelles within double-membraned vesicles and recycles the contents back into the cell. The interplay of autophagy with various membrane trafficking pathways is crucial for maintaining cellular homeostasis both under basal conditions and in response to environmental stress. In the CNS, neurons and glial cells rely on a spectrum of quality-control and recycling pathways, notably autophagy, to sustain the intricate functions of the brain. Genetic variants in autophagy genes are known to cause Mendelian disorders primarily affecting the human nervous system, underscoring the critical role of autophagy in brain function. We review the latest research delineating the landscape and network of autophagy in developing and mature neurons, elucidating how conserved autophagy pathways regulate neuronal homeostasis and functions at different ages. We examine the increasing evidence of dysfunctional autophagy that contributes to neurodevelopmental disorders, neurodegenerative diseases and psychiatric conditions. Recent insights into the dysregulation of autophagy provide valuable avenues for biomarker identification and therapeutic development, particularly targeting autophagy-lysosome pathways for neurological disorders.

DOI: https://doi.org/10.1038/s41593-026-02426-6
Nat Methods. 2026 Aug 27.

All-optical multimodal mapping of single-cell-type-specific metabolic activities via REDCAT.

Yajuan Li, Zhaojun Zhang, Archibald Enninful, Negin Farzad, Presha Rajbhandari, Hua Tian, Jungmin Nam, Xiaoyu Qin, Jorge Villazon, Anthony A Fung, Hongje Jang, Zhiliang Bai, Nancy R Zhang, Brent R Stockwell, Rong Fan, Mina L Xu, Zongming Ma, Lingyan Shi.

Metabolism is fundamental to cell function, yet its activities vary across tissue environments. Resolving these processes in situ at single-cell resolution is crucial for understanding physiology in health and disease. However, existing methods lack biochemical specificity or direct linkage to cell identity. Here we report a method, Raman Enhanced Delineation of Cell Atlases in Tissues (REDCAT), an all-optical platform integrating Raman scattering microscopy and high-plex immunofluorescence to co-map metabolism and cell types. REDCAT achieves subcellular profiling of protein, lipid, nuclear metabolites and redox metabolism in human tissues. In lymph nodes, it revealed cell-type-specific metabolic specialization. In lymphoma, REDCAT uncovered profound reprogramming and transitional states during tumor transformation. In the liver, it resolved zonation-dependent metabolic gradients. By linking cell identity to spatial metabolic states, REDCAT provides a framework for studying immunity and cancer, offering a path to deciphering the metabolic basis of disease.

DOI: https://doi.org/10.1038/s41592-026-03180-0
Chem Biomed Imaging. 2026 Aug 24. 4(8): 1740-1749

Fluorogenic Autophagic Vesicle-Engaging Probe Enables High-Contrast and Homogeneous Imaging of Autophagic Flux in Live Cells.

Ning Wang, Zhepei Lu, Yaping Lu, Xin Li.

  Autophagic flux is a highly dynamic process essential for cellular homeostasis, yet its reliable visualization in live cells remains challenging due to the limitations of transfection-based LC3 reporters. Here, we present ATP3, a fluorogenic and ratiometric chemical probe that directly engages autophagic vesicles to enable the high-contrast and homogeneous imaging of autophagic flux without genetic manipulation. ATP3 constitutes a guanine targeting moiety and a smart fluorophore, with the former facilitating autophagic vesicle engagement, while the latter is intrinsically quenched and environment-responsive. ATP3 exhibits minimal background fluorescence and robust signal amplification upon autophagy-dependent engagement. Side-by-side comparisons demonstrate that ATP3 outperforms the conventional mRFP-GFP-LC3 assay in imaging contrast and staining uniformity. Furthermore, ATP3 enables dynamic monitoring of autophagic responses in an oxygen-glucose deprivation model, revealing progressive enhancement of autophagic flux under ischemic stress. Together, ATP3 provides a robust and broadly applicable chemical tool for visualizing autophagy dynamics in physiologically and disease-relevant contexts.

Keywords:  autolysosome; autophagosome; autophagy; guanine; imaging; probe

DOI:  https://doi.org/10.1021/cbmi.5c00285
Nat Commun. 2026 Jul 24. pii: 9041. [Epub ahead of print]17(1):

Mitophagy mitigates mitochondrial DNA-induced activation of cGAS-STING in autoimmune thyroiditis.

Xiao-Chen Xie, Yang Guo, Ran Guo, Yong-Ze Li, Shan-Shan Wang, Xiao-You Jiang, Shuang Hao, Ye Zhang, Yu-Han Li, Xi-Yan Liu, Xiao-Xu Wu, Xin-Yue Zhang, Wen-Dong Guo, Yan-Ling Feng, Jia-Bin Li, Chen Liu, Liang Wang, Zhen-Hua Li, Wei-Ping Teng, Zhong-Yan Shan, Liu Cao, Qi-Qiang Guo.

Autoimmune thyroiditis arises from disrupted homeostasis of thyroid follicular epithelial cells and coordinated immune cell activation within the microenvironment. However, its pathogenesis is not fully understood. Here, we identify a mitochondrial (mt) DNA-cGAS-STING inflammatory axis as a driver of autoimmune thyroiditis in mice. By contrast, ubiquitin-dependent mitophagy mediated by PINK1 and Parkin was found to protect mice from disease. Mechanistically, mitochondrial dysfunction elevates mitochondrial reactive oxygen species levels, activating the ATM-CHK2 DNA damage response pathway, which in turn phosphorylates the autophagy adapter TAX1BP1 at Ser722. This modification promotes the recruitment of mitochondria to autophagosomes, thereby facilitating mitophagy. Impairing the ATM-CHK2-TAX1BP1 mitophagy pathway causes mtDNA leakage into the cytosol and triggers cGAS-STING-dependent inflammation. Notably, pharmacological inhibition of STING with C176 effectively slows autoimmune thyroiditis progression. Together, these findings define an mtDNA-driven pathogenic mechanism in autoimmune thyroiditis and identify STING as a potential therapeutic target.

DOI: https://doi.org/10.1038/s41467-026-76047-9
J Clin Invest. 2026 Sep 01. pii: e204023. [Epub ahead of print]

Excessive EFHD1-dependent ER-mitochondrial contacts drive a maladaptive antiviral response in metabolic liver disease.

David R Eberhardt, Emma C Rekate, Yasmin B Masini, Hannah E Duron, David Mollinedo, Adrian M Velarde, Devorah Stucki, Tara R Price, Sandra Hj Lee, Enrique Balderas, Neeraj K Rai, Ashley R Bratt, Anthony M Balynas, Chris J Stubben, Ryan Bia, Sudipa Maity, Nicolas Hartel, Xue Yin, Andrea Corbin, Anshu Kumari, Dung M Nguyen, Daisuke Shimura, Vu D Nguyen, Vishaka Vinod, Kamrul H Chowdhury, Francisco Verdeguer, Joel Zvick, Patrice N Mimche, Sihem Boudina, Stavros G Drakos, Ademuyiwa S Aromolaran, Sarah Franklin, Vivek Garg, Robin M Shaw, William L Holland, Scott A Summers, Marcus G Pezzolesi, Jared Rutter, Kimberley J Evason, Dipayan Chaudhuri.

  Metabolic-associated steatohepatitis (MASH) involves hepatocyte damage that cannot be explained solely by lipid accumulation. Here, to discover injury-specific pathways, we focused on a gene of uncertain function, EF-Hand Domain Family Member D1 (EFHD1), identified in human genome-wide association studies of liver injury but not liver fat. We show that EFHD1, a Ca2+-dependent actin crosslinker, stabilizes endoplasmic reticulum-mitochondria contact sites (ERMCS), detecting spatiotemporal coincidence of inter-organellar proximity and ER Ca2+ release. During MASH, EFHD1 upregulation drives pathological mitochondrial fragmentation via excessive contact persistence. This structural failure promotes mitochondrial double-stranded RNA escape and activation of a maladaptive antiviral PKR-associated stress response, a causal relationship also supported by Mendelian randomization in humans. Consequently, inhibiting EFHD1 in human and mouse models blunts hepatocyte damage. These findings identify EFHD1 as a Ca2+-dependent ERMCS stabilizer, reveal a hepatocyte-intrinsic injury pathway, and suggest EFHD1 inhibition as a therapeutic strategy.

Keywords:  Calcium signaling; Cell biology; Cellular immune response; Hepatology; Metabolism; Mitochondria

DOI:  https://doi.org/10.1172/JCI204023
Sci Adv. 2026 Aug 28. 12(35): eaee8657

The molecular basis of mitochondrial crista formation by the MIC10 complex.

Chelsea M Brown, Tsjerk A Wassenaar, Zachary Freyberg, Siewert J Marrink.

Mitochondrial cristae are essential for respiration, yet the molecular basis of how the high curvature of these membrane folds is maintained remains unclear. Using structure prediction tools and multiscale simulations, we examined the role of the MIC10 subcomplex of the mitochondrial contact site and cristae organizing system (MICOS). We found that the MIC10 proteins Mic10, Mic26, and Mic27 strongly recruit cardiolipin at conserved positive loop motifs, driving oligomerization of these subunits and resulting in the stabilization of curvature in model membranes. Reconstruction of the full MIC10 complex in a realistic crista junction setup shows its capability to maintain membrane bending, while intrinsically disordered regions may form a permeability barrier between cristae and the intermembrane space. These findings provide a mechanistic model for cristae curvature formation and suggest how MICOS components cooperate with cardiolipins to maintain mitochondrial architecture.

DOI: https://doi.org/10.1126/sciadv.aee8657
Sci Transl Med. 2026 Aug 26. 18(864): eady7616

A 3D human retina model reveals a non-cell-autonomous and non-neuronal mechanism of photoreceptor loss in a lysosomal storage disorder.

Jimin Han, Nathaniel Foley, Sonal Dalvi, Janet A H Tang, Fesahat Emira Dogrul, Amit Chatterjee, Lal Krishan Kumar, Chad A Galloway, Ajay Kumar Singh, Leah M Stein, Yashoda Subedi, Kevin C Ling, Alison Heffer, Xingxuan He, Vamsi K Gullapalli, Brent A Johnson, Richard T Libby, Danielle S W Benoit, Anthony L Cook, Vera L Bonilha, Edward H Schuchman, Jennifer J Hunter, Ruchira Singh.

Disruption of the photoreceptor-retinal pigment epithelium (RPE) interface, with loss of photoreceptor outer segments (POSs) in the retina, is a pathological hallmark of several neurodegenerative and retinal diseases, including lysosomal storage disorders like juvenile neuronal ceroid lipofuscinosis (CLN3) disease. However, in vitro stem cell models that enable investigation of the photoreceptor-RPE interface are lacking. Here, we developed a 3D human pluripotent stem cell-derived retina organoid-RPE (hPSC-RO-RPE) model to investigate the photoreceptor-RPE interface in healthy and diseased tissues. Using this 3D hPSC-RO-RPE retina model, we showed that the most common disease-causing CLN3 mutation (CLN3Δex7-8) leads to reduced levels of acid ceramidase (AC), sphingosine 1 phosphate, and POS loss. Furthermore, by analyzing control versus CLN3 mutant (CLN3Δex7-8) hPSC-derived RPE monoculture and hPSC-RO-RPE model, (i) we identified a pathogenic role of AC-mediated lysosomal sphingolipid metabolism in promoting CLN3 disease pathobiology, and (ii) we showed a cell autonomous role of the RPE dysfunction in promoting POS loss/retina degeneration in CLN3 disease. We validated the molecular and structural changes observed in the CLN3Δex7-8 hPSC-RO-RPE model in the CLN3 miniswine model (CLN3Δex7-8) and donor eyes from two patients with CLN3 disease. High-resolution retinal imaging of the living eye in two patients with CLN3 disease suggested decreased RPE autofluorescence in early-stage CLN3 disease. Treatment with recombinant human acid ceramidase (rhAC) ameliorated photoreceptor degeneration in both the CLN3 disease RO-RPE model and CLN3 miniswine eyes. These findings suggest that rhAC could be a therapeutic approach for retinal degeneration in CLN3 disease.

DOI: https://doi.org/10.1126/scitranslmed.ady7616