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Nature Aug 2023Dominant optic atrophy is one of the leading causes of childhood blindness. Around 60-80% of cases are caused by mutations of the gene that encodes optic atrophy protein...
Dominant optic atrophy is one of the leading causes of childhood blindness. Around 60-80% of cases are caused by mutations of the gene that encodes optic atrophy protein 1 (OPA1), a protein that has a key role in inner mitochondrial membrane fusion and remodelling of cristae and is crucial for the dynamic organization and regulation of mitochondria. Mutations in OPA1 result in the dysregulation of the GTPase-mediated fusion process of the mitochondrial inner and outer membranes. Here we used cryo-electron microscopy methods to solve helical structures of OPA1 assembled on lipid membrane tubes, in the presence and absence of nucleotide. These helical assemblies organize into densely packed protein rungs with minimal inter-rung connectivity, and exhibit nucleotide-dependent dimerization of the GTPase domains-a hallmark of the dynamin superfamily of proteins. OPA1 also contains several unique secondary structures in the paddle domain that strengthen its membrane association, including membrane-inserting helices. The structural features identified in this study shed light on the effects of pathogenic point mutations on protein folding, inter-protein assembly and membrane interactions. Furthermore, mutations that disrupt the assembly interfaces and membrane binding of OPA1 cause mitochondrial fragmentation in cell-based assays, providing evidence of the biological relevance of these interactions.
Topics: Cryoelectron Microscopy; GTP Phosphohydrolases; Membrane Fusion; Mitochondria; Mitochondrial Dynamics; Mitochondrial Membranes; Mutation; Nucleotides; Protein Binding; Protein Domains; Protein Folding; Protein Multimerization; Protein Structure, Secondary; Humans
PubMed: 37612506
DOI: 10.1038/s41586-023-06462-1 -
ACS Nano Dec 2023The increasing understanding of ferroptosis has indicated its role and therapeutic potential in cancer; however, this knowledge has yet to be translated into effective...
The increasing understanding of ferroptosis has indicated its role and therapeutic potential in cancer; however, this knowledge has yet to be translated into effective therapies. Glioblastoma (GBM) patients face a bleak prognosis and encounter challenges due to the limited treatment options available. In this study, we conducted a genome-wide CRISPR-Cas9 screening in the presence of a ferroptosis inducer (RSL3) to identify the key driver genes involved in ferroptosis. We identified ALOX15, a key lipoxygenase (LOX), as an essential driver of ferroptosis. Small activating RNA (saRNA) was used to mediate the expression of ALOX15 promoted ferroptosis in GBM cells. We then coated saALOX15-loaded mesoporous polydopamine (MPDA) with Angiopep-2-modified macrophage membranes (MMs) to reduce the clearance by the mononuclear phagocyte system (MPS) and increase the ability of the complex to cross the blood-brain barrier (BBB) during specific targeted therapy of orthotopic GBM. These generated hybrid nanoparticles (NPs) induced ferroptosis by mediating mitochondrial dysfunction and rendering mitochondrial morphology abnormal. In vivo, the modified MM enabled the NPs to target GBM cells, exert a marked inhibitory effect on GBM progression, and promote GBM radiosensitivity. Our results reveal ALOX15 to be a promising therapeutic target in GBM and suggest a biomimetic strategy that depends on the biological properties of MMs to enhance the in vivo performance of NPs for treating GBM.
Topics: Humans; Glioblastoma; Biomimetics; Ferroptosis; Macrophages; Nanoparticles; Cell Line, Tumor; Brain Neoplasms
PubMed: 37991252
DOI: 10.1021/acsnano.3c07555 -
Nature Chemical Biology Jun 2024Ferroptosis is iron-dependent oxidative cell death. Labile iron and polyunsaturated fatty acid (PUFA)-containing lipids are two critical factors for ferroptosis...
Ferroptosis is iron-dependent oxidative cell death. Labile iron and polyunsaturated fatty acid (PUFA)-containing lipids are two critical factors for ferroptosis execution. Many processes regulating iron homeostasis and lipid synthesis are critically involved in ferroptosis. However, it remains unclear whether biological processes other than iron homeostasis and lipid synthesis are associated with ferroptosis. Using kinase inhibitor library screening, we discovered a small molecule named CGI1746 that potently blocks ferroptosis. Further studies demonstrate that CGI1746 acts through sigma-1 receptor (σR), a chaperone primarily located at mitochondria-associated membranes (MAMs), to inhibit ferroptosis. Suppression of σR protects mice from cisplatin-induced acute kidney injury hallmarked by ferroptosis. Mechanistically, CGI1746 treatment or genetic disruption of MAMs leads to defective Ca transfer, mitochondrial reactive oxygen species (ROS) production and PUFA-containing triacylglycerol accumulation. Therefore, we propose a critical role for MAMs in ferroptosis execution.
Topics: Ferroptosis; Receptors, sigma; Animals; Mice; Sigma-1 Receptor; Humans; Reactive Oxygen Species; Mitochondria; Mitochondrial Membranes; Mice, Inbred C57BL; Mitochondria Associated Membranes
PubMed: 38212578
DOI: 10.1038/s41589-023-01512-1 -
Nature Communications Oct 2023Mitochondrial function is vital for energy metabolism in thermogenic adipocytes. Impaired mitochondrial bioenergetics in brown adipocytes are linked to disrupted...
Mitochondrial function is vital for energy metabolism in thermogenic adipocytes. Impaired mitochondrial bioenergetics in brown adipocytes are linked to disrupted thermogenesis and energy balance in obesity and aging. Phospholipid cardiolipin (CL) and phosphatidic acid (PA) jointly regulate mitochondrial membrane architecture and dynamics, with mitochondria-associated endoplasmic reticulum membranes (MAMs) serving as the platform for phospholipid biosynthesis and metabolism. However, little is known about the regulators of MAM phospholipid metabolism and their connection to mitochondrial function. We discover that LCN2 is a PA binding protein recruited to the MAM during inflammation and metabolic stimulation. Lcn2 deficiency disrupts mitochondrial fusion-fission balance and alters the acyl-chain composition of mitochondrial phospholipids in brown adipose tissue (BAT) of male mice. Lcn2 KO male mice exhibit an increase in the levels of CLs containing long-chain polyunsaturated fatty acids (LC-PUFA), a decrease in CLs containing monounsaturated fatty acids, resulting in mitochondrial dysfunction. This dysfunction triggers compensatory activation of peroxisomal function and the biosynthesis of LC-PUFA-containing plasmalogens in BAT. Additionally, Lcn2 deficiency alters PA production, correlating with changes in PA-regulated phospholipid-metabolizing enzymes and the mTOR signaling pathway. In conclusion, LCN2 plays a critical role in the acyl-chain remodeling of phospholipids and mitochondrial bioenergetics by regulating PA production and its function in activating signaling pathways.
Topics: Animals; Male; Mice; Adipocytes, Brown; Adipose Tissue, Brown; Lipocalin-2; Mice, Inbred C57BL; Mice, Knockout; Mitochondria; Plasmalogens; Thermogenesis
PubMed: 37872178
DOI: 10.1038/s41467-023-42473-2 -
Nature Communications Jul 2023Glioblastoma (GBM) remains the most lethal malignant tumours. Gboxin, an oxidative phosphorylation inhibitor, specifically restrains GBM growth by inhibiting the...
Glioblastoma (GBM) remains the most lethal malignant tumours. Gboxin, an oxidative phosphorylation inhibitor, specifically restrains GBM growth by inhibiting the activity of FF ATPase complex V. However, its anti-GBM effect is seriously limited by poor blood circulation, the blood brain barrier (BBB) and non-specific GBM tissue/cell uptake, leading to insufficient Gboxin accumulation at GBM sites, which limits its further clinical application. Here we present a biomimetic nanomedicine (HM-NPs@G) by coating cancer cell-mitochondria hybrid membrane (HM) on the surface of Gboxin-loaded nanoparticles. An additional design element uses a reactive oxygen species responsive polymer to facilitate at-site Gboxin release. The HM camouflaging endows HM-NPs@G with unique features including good biocompatibility, improved pharmacokinetic profile, efficient BBB permeability and homotypic dual tumour cell and mitochondria targeting. The results suggest that HM-NPs@G achieve improved blood circulation (4.90 h versus 0.47 h of free Gboxin) and tumour accumulation (7.73% ID/g versus 1.06% ID/g shown by free Gboxin). Effective tumour inhibition in orthotopic U87MG GBM and patient derived X01 GBM stem cell xenografts in female mice with extended survival time and negligible side effects are also noted. We believe that the biomimetic Gboxin nanomedicine represents a promising treatment for brain tumours with clinical potential.
Topics: Humans; Female; Animals; Mice; Glioblastoma; Nanomedicine; Cell Line, Tumor; Mitochondrial Membranes; Blood-Brain Barrier; Mitochondria; Nanoparticles; Brain Neoplasms
PubMed: 37507371
DOI: 10.1038/s41467-023-40280-3 -
Cell Reports Dec 2023Apolipoproteins L1 and L3 (APOLs) are associated at the Golgi with the membrane fission factors phosphatidylinositol 4-kinase-IIIB (PI4KB) and non-muscular myosin 2A....
Apolipoproteins L1 and L3 (APOLs) are associated at the Golgi with the membrane fission factors phosphatidylinositol 4-kinase-IIIB (PI4KB) and non-muscular myosin 2A. Either APOL1 C-terminal truncation (APOL1Δ) or APOL3 deletion (APOL3-KO [knockout]) reduces PI4KB activity and triggers actomyosin reorganization. We report that APOL3, but not APOL1, controls PI4KB activity through interaction with PI4KB and neuronal calcium sensor-1 or calneuron-1. Both APOLs are present in Golgi-derived autophagy-related protein 9A vesicles, which are involved in PI4KB trafficking. Like APOL3-KO, APOL1Δ induces PI4KB dissociation from APOL3, linked to reduction of mitophagy flux and production of mitochondrial reactive oxygen species. APOL1 and APOL3, respectively, can interact with the mitophagy receptor prohibitin-2 and the mitophagosome membrane fusion factor vesicle-associated membrane protein-8 (VAMP8). While APOL1 conditions PI4KB and APOL3 involvement in mitochondrion fission and mitophagy, APOL3-VAMP8 interaction promotes fusion between mitophagosomal and endolysosomal membranes. We propose that APOL3 controls mitochondrial membrane dynamics through interactions with the fission factor PI4KB and the fusion factor VAMP8.
Topics: Apolipoprotein L1; Mitochondrial Membranes; Golgi Apparatus; Mitochondria; 1-Phosphatidylinositol 4-Kinase; Apolipoproteins; Mitochondrial Dynamics
PubMed: 38041817
DOI: 10.1016/j.celrep.2023.113528 -
Molecular Cell Feb 2024Organelle transporters define metabolic compartmentalization, and how this metabolite transport process can be modulated is poorly explored. Here, we discovered that...
Organelle transporters define metabolic compartmentalization, and how this metabolite transport process can be modulated is poorly explored. Here, we discovered that human SLC25A39, a mitochondrial transporter critical for mitochondrial glutathione uptake, is a short-lived protein under dual regulation at the protein level. Co-immunoprecipitation mass spectrometry and CRISPR knockout (KO) in mammalian cells identified that mitochondrial m-AAA protease AFG3L2 is responsible for degrading SLC25A39 through the matrix loop 1. SLC25A39 senses mitochondrial iron-sulfur cluster using four matrix cysteine residues and inhibits its degradation. SLC25A39 protein regulation is robust in developing and mature neurons. This dual transporter regulation, by protein quality control and metabolic sensing, allows modulating mitochondrial glutathione level in response to iron homeostasis, opening avenues for exploring regulation of metabolic compartmentalization. Neuronal SLC25A39 regulation connects mitochondrial protein quality control, glutathione, and iron homeostasis, which were previously unrelated biochemical features in neurodegeneration.
Topics: Animals; Humans; ATPases Associated with Diverse Cellular Activities; ATP-Dependent Proteases; Iron; Mitochondria; Mitochondrial Proteins; Homeostasis; Glutathione; Mammals; Mitochondrial Membrane Transport Proteins
PubMed: 38157846
DOI: 10.1016/j.molcel.2023.12.008 -
Nature Communications Sep 2023Abnormal distribution of cellular cholesterol is associated with numerous diseases, including cardiovascular and neurodegenerative diseases. Regulated transport of...
Abnormal distribution of cellular cholesterol is associated with numerous diseases, including cardiovascular and neurodegenerative diseases. Regulated transport of cholesterol is critical for maintaining its proper distribution in the cell, yet the underlying mechanisms remain unclear. Here, we show that lipid transfer proteins, namely ORP9, OSBP, and GRAMD1s/Asters (GRAMD1a/GRAMD1b/GRAMD1c), control non-vesicular cholesterol transport at points of contact between the ER and the trans-Golgi network (TGN), thereby maintaining cellular cholesterol distribution. ORP9 localizes to the TGN via interaction between its tandem α-helices and ORP10/ORP11. ORP9 extracts PI4P from the TGN to prevent its overaccumulation and suppresses OSBP-mediated PI4P-driven cholesterol transport to the Golgi. By contrast, GRAMD1s transport excess cholesterol from the Golgi to the ER, thereby preventing its build-up. Cells lacking ORP9 exhibit accumulation of cholesterol at the Golgi, which is further enhanced by additional depletion of GRAMD1s with major accumulation in the plasma membrane. This is accompanied by chronic activation of the SREBP-2 signalling pathway. Our findings reveal the importance of regulated lipid transport at ER-Golgi contacts for maintaining cellular cholesterol distribution and homeostasis.
Topics: Mitochondrial Membranes; Golgi Apparatus; trans-Golgi Network; Biological Transport; Cholesterol
PubMed: 37735529
DOI: 10.1038/s41467-023-41213-w -
Biomolecules Aug 2023Mitochondrial network architecture plays a critical role in cellular physiology. Indeed, alterations in the shape of mitochondria upon exposure to cellular stress can... (Review)
Review
Mitochondrial network architecture plays a critical role in cellular physiology. Indeed, alterations in the shape of mitochondria upon exposure to cellular stress can cause the dysfunction of these organelles. In this scenario, mitochondrial dynamics proteins and the phospholipid composition of the mitochondrial membrane are key for fine-tuning the modulation of mitochondrial architecture. In addition, several factors including post-translational modifications such as the phosphorylation, acetylation, SUMOylation, and o-GlcNAcylation of mitochondrial dynamics proteins contribute to shaping the plasticity of this architecture. In this regard, several studies have evidenced that, upon metabolic stress, mitochondrial dynamics proteins are post-translationally modified, leading to the alteration of mitochondrial architecture. Interestingly, several proteins that sustain the mitochondrial lipid composition also modulate mitochondrial morphology and organelle communication. In this context, pharmacological studies have revealed that the modulation of mitochondrial shape and function emerges as a potential therapeutic strategy for metabolic diseases. Here, we review the factors that modulate mitochondrial architecture.
Topics: Mitochondria; Mitochondrial Membranes; Acetylation; Mitochondrial Dynamics; Mitochondrial Proteins
PubMed: 37627290
DOI: 10.3390/biom13081225 -
Redox Biology Apr 2024To investigate the regulatory effect and mechanism of Vitamin D receptor (VDR) on mitochondrial function in renal tubular epithelial cell under diabetic status.
PURPOSE
To investigate the regulatory effect and mechanism of Vitamin D receptor (VDR) on mitochondrial function in renal tubular epithelial cell under diabetic status.
METHODS
The diabetic rats induced by streptozotocin (STZ) and HK-2 cells under high glocose(HG)/transforming growth factor beta (TGF-β) stimulation were used in this study. Calcitriol was administered for 24 weeks. Renal tubulointerstitial injury and some parameters of mitochondrial function including mitophagy, mitochondrial fission, mitochondrial ROS, mitochondrial membrane potential (MMP), mitochondrial ATP, Complex V activity and mitochondria-associated ER membranes (MAMs) integrity were examined. Additionally, paricalcitol, 3-MA (an autophagy inhibitor), VDR over-expression plasmid, VDR siRNA and Mfn2 siRNA were applied in vitro.
RESULTS
The expression of VDR, Pink1, Parkin, Fundc1, LC3II, Atg5, Mfn2, Mfn1 in renal tubular cell of diabetic rats were decreased significantly. Calcitriol treatment reduced the levels of urinary albumin, serum creatinine and attenuated renal tubulointerstitial fibrosis in STZ induced diabetic rats. In addition, VDR agonist relieved mitophagy dysfunction, MAMs integrity, and inhibited mitochondrial fission, mitochondrial ROS. Co-immunoprecipitation analysis demonstrated that VDR interacted directly with Mfn2. Mitochondrial function including mitophagy, mitochondrial membrane potential (MMP), mitochondrial Ca, mitochondrial ATP and Complex V activity were decreased dramatically in HK-2 cells under HG/TGF-β ambience. In vitro pretreatment of HK-2 cells with autophagy inhibitor 3-MA, VDR siRNA or Mfn2 siRNA negated the activating effects of paricalcitol on mitochondrial function. Pricalcitol and VDR over-expression plasmid activated Mfn2 and then partially restored the MAMs integrity. Additionally, VDR restored mitophagy was partially associated with MAMs integrity through Fundc1.
CONCLUSION
Activated VDR could contribute to restore mitophagy through Mfn2-MAMs-Fundc1 pathway in renal tubular cell. VDR could recover mitochondrial ATP, complex V activity and MAMs integrity, inhibit mitochondrial fission and mitochondrial ROS. It indicating that VDR agonists ameliorate renal tubulointerstitial fibrosis in diabetic rats partially via regulation of mitochondrial function.
Topics: Animals; Rats; Adenosine Triphosphate; Calcitriol; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Epithelial Cells; Fibrosis; Mitochondria; Reactive Oxygen Species; Receptors, Calcitriol; RNA, Small Interfering; Transforming Growth Factor beta
PubMed: 38320454
DOI: 10.1016/j.redox.2024.103062