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He Y, Fan Y, Ahmadpoor X, Wang Y, Li ZA, Zhu W, Lin H. Targeting lysosomal quality control as a therapeutic strategy against aging and diseases. Med Res Rev 2024. [PMID: 38711187 DOI: 10.1002/med.22047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 04/04/2024] [Accepted: 04/21/2024] [Indexed: 05/08/2024]
Abstract
Previously, lysosomes were primarily referred to as the digestive organelles and recycling centers within cells. Recent discoveries have expanded the lysosomal functional scope and revealed their critical roles in nutrient sensing, epigenetic regulation, plasma membrane repair, lipid transport, ion homeostasis, and cellular stress response. Lysosomal dysfunction is also found to be associated with aging and several diseases. Therefore, function of macroautophagy, a lysosome-dependent intracellular degradation system, has been identified as one of the updated twelve hallmarks of aging. In this review, we begin by introducing the concept of lysosomal quality control (LQC), which is a cellular machinery that maintains the number, morphology, and function of lysosomes through different processes such as lysosomal biogenesis, reformation, fission, fusion, turnover, lysophagy, exocytosis, and membrane permeabilization and repair. Next, we summarize the results from studies reporting the association between LQC dysregulation and aging/various disorders. Subsequently, we explore the emerging therapeutic strategies that target distinct aspects of LQC for treating diseases and combatting aging. Lastly, we underscore the existing knowledge gap and propose potential avenues for future research.
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Affiliation(s)
- Yuchen He
- Department of Orthopaedics, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
- Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Yishu Fan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xenab Ahmadpoor
- Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Yumin Wang
- Department of Otolaryngology Head and Neck Surgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhong Alan Li
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
- Center for Neuromusculoskeletal Restorative Medicine, Hong Kong Science Park, Shatin, NT, Hong Kong SAR, China
| | - Weihong Zhu
- Department of Orthopaedics, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
- Department of Orthopaedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Hang Lin
- Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, Pennsylvania, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Pan Y, Xin W, Wei W, Tatenhorst L, Graf I, Popa-Wagner A, Gerner ST, Huber SE, Kilic E, Hermann DM, Bähr M, Huttner HB, Doeppner TR. Knockdown of NEAT1 prevents post-stroke lipid droplet agglomeration in microglia by regulating autophagy. Cell Mol Life Sci 2024; 81:30. [PMID: 38212456 PMCID: PMC10784396 DOI: 10.1007/s00018-023-05045-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/06/2023] [Accepted: 11/09/2023] [Indexed: 01/13/2024]
Abstract
BACKGROUND Lipid droplets (LD), lipid-storing organelles containing neutral lipids like glycerolipids and cholesterol, are increasingly accepted as hallmarks of inflammation. The nuclear paraspeckle assembly transcript 1 (NEAT1), a long non-coding RNA with over 200 nucleotides, exerts an indispensable impact on regulating both LD agglomeration and autophagy in multiple neurological disorders. However, knowledge as to how NEAT1 modulates the formation of LD and associated signaling pathways is limited. METHODS In this study, primary microglia were isolated from newborn mice and exposed to oxygen-glucose-deprivation/reoxygenation (OGD/R). To further explore NEAT1-dependent mechanisms, an antisense oligonucleotide (ASO) was adopted to silence NEAT1 under in vitro conditions. Studying NEAT1-dependent interactions with regard to autophagy and LD agglomeration under hypoxic conditions, the inhibitor and activator of autophagy 3-methyladenine (3-MA) and rapamycin (RAPA) were used, respectively. In a preclinical stroke model, mice received intraventricular injections of ASO NEAT1 or control vectors in order to yield NEAT1 knockdown. Analysis of readout parameters included qRT-PCR, immunofluorescence, western blot assays, and behavioral tests. RESULTS Microglia exposed to OGD/R displayed a temporal pattern of NEAT1 expression, peaking at four hours of hypoxia followed by six hours of reoxygenation. After effectively silencing NEAT1, LD formation and autophagy-related proteins were significantly repressed in hypoxic microglia. Stimulating autophagy in ASO NEAT1 microglia under OGD/R conditions by means of RAPA reversed the downregulation of LD agglomeration and perilipin 2 (PLIN2) expression. On the contrary, application of 3-MA promoted repression of both LD agglomeration and expression of the LD-associated protein PLIN2. Under in vivo conditions, NEAT1 was significantly increased in mice at 24 h post-stroke. Knockdown of NEAT1 significantly alleviated LD agglomeration and inhibited autophagy, resulting in improved cerebral perfusion, reduced brain injury and increased neurological recovery. CONCLUSION NEAT1 is a key player of LD agglomeration and autophagy stimulation, and NEAT1 knockdown provides a promising therapeutic value against stroke.
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Affiliation(s)
- Yongli Pan
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Wenqiang Xin
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Wei Wei
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Lars Tatenhorst
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Irina Graf
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Aurel Popa-Wagner
- Department of Neurology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Stefan T Gerner
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Sabine E Huber
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Ertugrul Kilic
- Department of Physiology, Faculty of Medicine, Istanbul Medeniyet University, Istanbul, Turkey
| | - Dirk M Hermann
- Department of Neurology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Mathias Bähr
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Hagen B Huttner
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Thorsten R Doeppner
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany.
- Department of Neurology, University of Giessen Medical School, Giessen, Germany.
- Department of Anatomy and Cell Biology, Medical University of Varna, Varna, Bulgaria.
- Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Giessen, Germany.
- Research Institute for Health Sciences and Technologies (SABITA), Medipol University, Istanbul, Turkey.
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Wei W, Zhang L, Xin W, Pan Y, Tatenhorst L, Hao Z, Gerner ST, Huber S, Juenemann M, Butz M, Huttner HB, Bähr M, Fitzner D, Jia F, Doeppner TR. TREM2 regulates microglial lipid droplet formation and represses post-ischemic brain injury. Biomed Pharmacother 2024; 170:115962. [PMID: 38042110 DOI: 10.1016/j.biopha.2023.115962] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/14/2023] [Accepted: 11/27/2023] [Indexed: 12/04/2023] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane receptor protein predominantly expressed in microglia within the central nervous system (CNS). TREM2 regulates multiple microglial functions, including lipid metabolism, immune reaction, inflammation, and microglial phagocytosis. Recent studies have found that TREM2 is highly expressed in activated microglia after ischemic stroke. However, the role of TREM2 in the pathologic response after stroke remains unclear. Herein, TREM2-deficient microglia exhibit an impaired phagocytosis rate and cholesteryl ester (CE) accumulation, leading to lipid droplet formation and upregulation of Perilipin-2 (PLIN2) expression after hypoxia. Knockdown of TREM2 results in increased lipid synthesis (PLIN2, SOAT1) and decreased cholesterol clearance and lipid hydrolysis (LIPA, ApoE, ABCA1, NECH1, and NPC2), further impacting microglial phenotypes. In these lipid droplet-rich microglia, the TGF-β1/Smad2/3 signaling pathway is downregulated, driving microglia towards a pro-inflammatory phenotype. Meanwhile, in a neuron-microglia co-culture system under hypoxic conditions, we found that microglia lost their protective effect against neuronal injury and apoptosis when TREM2 was knocked down. Under in vivo conditions, TREM2 knockdown mice express lower TGF-β1 expression levels and a lower number of anti-inflammatory M2 phenotype microglia, resulting in increased cerebral infarct size, exacerbated neuronal apoptosis, and aggravated neuronal impairment. Our work suggests that TREM2 attenuates stroke-induced neuroinflammation by modulating the TGF-β1/Smad2/3 signaling pathway. TREM2 may play a direct role in the regulation of inflammation and also exert an influence on the post-ischemic inflammation and the stroke pathology progression via regulation of lipid metabolism processes. Thus, underscoring the therapeutic potential of TREM2 agonists in ischemic stroke and making TREM2 an attractive new clinical target for the treatment of ischemic stroke and other inflammation-related diseases.
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Affiliation(s)
- Wei Wei
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Lin Zhang
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenqiang Xin
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Yongli Pan
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Lars Tatenhorst
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Zhongnan Hao
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Stefan T Gerner
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Sabine Huber
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Martin Juenemann
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Marius Butz
- Heart and Brain Research Group, Kerckhoff Heart and Thorax Center, Bad Nauheim, Germany
| | - Hagen B Huttner
- Department of Neurology, University of Giessen Medical School, Giessen, Germany
| | - Mathias Bähr
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - Dirk Fitzner
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany.
| | - Feng Jia
- Department of Neurosurgery, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Neurosurgery, Nantong First People's Hospital, Affiliated Hospital 2 of Nantong University, Nantong, China.
| | - Thorsten R Doeppner
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany; Department of Neurology, University of Giessen Medical School, Giessen, Germany; Department of Anatomy and Cell Biology, Medical University of Varna, Varna, Bulgaria; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University Giessen, Giessen, Germany; Research Institute for Health Sciences and Technologies (SABITA), Medipol University, Istanbul, Turkey.
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Xin W, Pan Y, Wei W, Gerner ST, Huber S, Juenemann M, Butz M, Bähr M, Huttner HB, Doeppner TR. TGF-β1 Decreases Microglia-Mediated Neuroinflammation and Lipid Droplet Accumulation in an In Vitro Stroke Model. Int J Mol Sci 2023; 24:17329. [PMID: 38139158 PMCID: PMC10743979 DOI: 10.3390/ijms242417329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/05/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
Hypoxia triggers reactive microglial inflammation and lipid droplet (LD) accumulation under stroke conditions, although the mutual interactions between these two processes are insufficiently understood. Hence, the involvement of transforming growth factor (TGF)-β1 in inflammation and LD accumulation in cultured microglia exposed to hypoxia were analyzed herein. Primary microglia were exposed to oxygen-glucose deprivation (OGD) injury and lipopolysaccharide (LPS) stimulation. For analyzing the role of TGF-β1 patterns under such conditions, a TGF-β1 siRNA and an exogenous recombinant TGF-β1 protein were employed. Further studies applied Triacsin C, an inhibitor of LD formation, in order to directly assess the impact of LD formation on the modulation of inflammation. To assess mutual microglia-to-neuron interactions, a co-culture model of these cells was established. Upon OGD exposure, microglial TGF-β1 levels were significantly increased, whereas LPS stimulation yielded decreased levels. Elevating TGF-β1 expression proved highly effective in suppressing inflammation and reducing LD accumulation in microglia exposed to LPS. Conversely, inhibition of TGF-β1 led to the promotion of microglial cell inflammation and an increase in LD accumulation in microglia exposed to OGD. Employing the LD formation inhibitor Triacsin C, in turn, polarized microglia towards an anti-inflammatory phenotype. Such modulation of both microglial TGF-β1 and LD levels significantly affected the resistance of co-cultured neurons. This study provides novel insights by demonstrating that TGF-β1 plays a protective role against microglia-mediated neuroinflammation through the suppression of LD accumulation. These findings offer a fresh perspective on stroke treatment, suggesting the potential of targeting this pathway for therapeutic interventions.
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Affiliation(s)
- Wenqiang Xin
- Department of Neurology, University of Göttingen Medical School, 37075 Goettingen, Germany; (W.X.); (Y.P.); (W.W.); (M.B.)
| | - Yongli Pan
- Department of Neurology, University of Göttingen Medical School, 37075 Goettingen, Germany; (W.X.); (Y.P.); (W.W.); (M.B.)
| | - Wei Wei
- Department of Neurology, University of Göttingen Medical School, 37075 Goettingen, Germany; (W.X.); (Y.P.); (W.W.); (M.B.)
| | - Stefan T. Gerner
- Department of Neurology, University of Giessen Medical School, 35392 Giessen, Germany; (S.T.G.); (M.J.); (M.B.); (H.B.H.)
- Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University, 35032 Giessen, Germany
| | - Sabine Huber
- Department of Neurology, University of Giessen Medical School, 35392 Giessen, Germany; (S.T.G.); (M.J.); (M.B.); (H.B.H.)
| | - Martin Juenemann
- Department of Neurology, University of Giessen Medical School, 35392 Giessen, Germany; (S.T.G.); (M.J.); (M.B.); (H.B.H.)
| | - Marius Butz
- Department of Neurology, University of Giessen Medical School, 35392 Giessen, Germany; (S.T.G.); (M.J.); (M.B.); (H.B.H.)
- Heart and Brain Research Group, Kerckhoff Heart and Thorax Center, 61231 Bad Nauheim, Germany
| | - Mathias Bähr
- Department of Neurology, University of Göttingen Medical School, 37075 Goettingen, Germany; (W.X.); (Y.P.); (W.W.); (M.B.)
| | - Hagen B. Huttner
- Department of Neurology, University of Giessen Medical School, 35392 Giessen, Germany; (S.T.G.); (M.J.); (M.B.); (H.B.H.)
| | - Thorsten R. Doeppner
- Department of Neurology, University of Göttingen Medical School, 37075 Goettingen, Germany; (W.X.); (Y.P.); (W.W.); (M.B.)
- Department of Neurology, University of Giessen Medical School, 35392 Giessen, Germany; (S.T.G.); (M.J.); (M.B.); (H.B.H.)
- Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus Liebig University, 35032 Giessen, Germany
- Department of Anatomy and Cell Biology, Medical University of Varna, 9238 Varna, Bulgaria
- Research Institute for Health Sciences and Technologies (SABITA), Medipol University, 100098 Istanbul, Turkey
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