scholarly journals SEIPIN: A Key Factor for Nuclear Lipid Droplet Generation and Lipid Homeostasis

2020 ◽  
Vol 21 (21) ◽  
pp. 8208
Author(s):  
Yi Jin ◽  
Yanjie Tan ◽  
Pengxiang Zhao ◽  
Zhuqing Ren
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Droplet ◽  
Normal Cell ◽  
Single Layer ◽  
Lipid Homeostasis ◽  
Cell Physiology ◽  
Phospholipid Membrane ◽  
Key Factor

Lipid homeostasis is essential for normal cell physiology. Generally, lipids are stored in a lipid droplet (LD), a ubiquitous organelle consisting of a neutral lipid core and a single layer of phospholipid membrane. It is thought that LDs are generated from the endoplasmic reticulum and then released into the cytosol. Recent studies indicate that LDs can exist in the nucleus, where they play an important role in the maintenance of cell phospholipid homeostasis. However, the details of nuclear lipid droplet (nLD) generation have not yet been clearly characterized. SEIPIN is a nonenzymatic protein encoded by the Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) gene. It is associated with lipodystrophy diseases. Many recent studies have indicated that SEIPIN is essential for LDs generation. Here, we review much of this research in an attempt to explain the role of SEIPIN in nLD generation. From an integrative perspective, we conclude by proposing a theoretical model to explain how SEIPIN might participate in maintaining homeostasis of lipid metabolism.

scholarly journals Lipid perturbation-activated IRE-1 modulates autophagy and lipolysis during endoplasmic reticulum stress

2018 ◽  
Author(s):  
Jhee Hong Koh ◽  
Lei Wang ◽  
Caroline Beaudoin-Chabot ◽  
Guillaume Thibault
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Lipid Droplet ◽  
Metabolic Diseases ◽  
Phospholipid Composition ◽  
Emerging Diseases ◽  
Lipid Homeostasis ◽  
Dependent Manner ◽  
Proteotoxic Stress

ABSTRACTMetabolic disorders such as obesity and nonalcoholic fatty liver disease (NAFLD) are emerging diseases that affect the global population. One facet of these disorders is attributed to the disturbance of membrane lipid composition. Perturbation of endoplasmic reticulum (ER) homeostasis through changes in membrane phospholipid composition results in activation of the unfolded protein response (UPR) and causes dramatic translational and transcriptional changes in the cell. To restore cellular homeostasis, the three highly conserved UPR transducers ATF6, IRE1, and PERK mediate cellular processes upon ER stress. The role of the UPR in proteotoxic stress caused by the accumulation of misfolded proteins is well understood but much less so under lipid perturbation-induced UPR (UPRLP). We found that genetically disrupted phosphatidylcholine synthesis in C. elegans causes, lipid perturbation, lipid droplet accumulation, and induced ER stress, all hallmarks of NAFLD. Transcriptional profiling of UPRLP animals shows a unique subset of genes modulated in an UPR-dependent manner that is unaffected by proteotoxic stress (UPRPT). Among these, we identified autophagy genes bec-1 and lgg-1 and the lipid droplet-associated lipase atgl-1 to be modulated by IRE-1. Considering the important role of lipid homeostasis and how its impairment contributes to the pathology of metabolic diseases, our data uncovers the indispensable role of a fully functional UPR program in regulating lipid homeostasis in the face of chronic ER stress and lipotoxicity.

scholarly journals Promethin Is a Conserved Seipin Partner Protein

Cells ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 268 ◽  
Author(s):  
Inês Castro ◽  
Michal Eisenberg-Bord ◽  
Elisa Persiani ◽  
Justin Rochford ◽  
Maya Schuldiner ◽  
...  
Keyword(s):  
Human Health ◽  
Lipid Droplet ◽  
Storage Disease ◽  
Human Protein ◽  
Partner Protein ◽  
Evolutionarily Conserved ◽  
Key Factor ◽  
Related Proteins

Seipin (BSCL2/SPG17) is a key factor in lipid droplet (LD) biology, and its dysfunction results in severe pathologies, including the fat storage disease Berardinelli-Seip congenital lipodystrophy type 2, as well as several neurological seipinopathies. Despite its importance for human health, the molecular role of seipin is still enigmatic. Seipin is evolutionarily conserved from yeast to humans. In yeast, seipin was recently found to cooperate with the lipid droplet organization (LDO) proteins, Ldo16 and Ldo45, two structurally-related proteins involved in LD function and identity that display remote homology to the human protein promethin/TMEM159. In this study, we show that promethin is indeed an LD-associated protein that forms a complex with seipin, and its localization to the LD surface can be modulated by seipin expression levels. We thus identify promethin as a novel seipin partner protein.

Role of mTOR1 and mTOR2 complexes in MEG-01 cell physiology

2015 ◽  
Vol 114 (11) ◽  
pp. 969-981 ◽  
Author(s):  
Esther López ◽  
Alejandro Berna-Erro ◽  
Javier J. López ◽  
María P. Granados ◽  
Nuria Bermejo ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Mammalian Target Of Rapamycin ◽  
Target Of Rapamycin ◽  
Cell Physiology ◽  
Cell Stimulation ◽  
Intracellular Location ◽  
Macromolecular Complexes

SummaryThe function of the mammalian target of rapamycin (mTOR) is upregulated in response to cell stimulation with growing and differentiating factors. Active mTOR controls cell proliferation, differentiation and death. Since mTOR associates with different proteins to form two functional macromolecular complexes, we aimed to investigate the role of the mTORI and mTOR2 complexes in MEG-01 cell physiology in response to thrombopoietin (TPO). By using mTOR antagonists and overexpressing FKBP38, we have explored the role of both mTOR complexes in proliferation, apoptosis, maturation-like mechanisms, endoplasmic reticulum-stress and the intracellular location of both active mTOR complexes during MEG-01 cell stimulation with TPO. The results demonstrate that mTOR1 and mTOR2 complexes play different roles in the physiology of MEG-01 cells and in the maturation-like mechanisms; hence, these findings might help to understand the mechanism underlying generation of platelets.

scholarly journals Genes and Diet in the Prevention of Chronic Diseases in Future Generations

2020 ◽  
Vol 21 (7) ◽  
pp. 2633 ◽  
Author(s):  
Marica Franzago ◽  
Daniele Santurbano ◽  
Ester Vitacolonna ◽  
Liborio Stuppia
Keyword(s):  
Human Health ◽  
Dietary Intervention ◽  
Nutrient Requirements ◽  
Metabolic Disturbances ◽  
Transgenerational Transmission ◽  
Key Factor ◽  
Dietary Components ◽  
Diabetes Gestational

Nutrition is a modifiable key factor that is able to interact with both the genome and epigenome to influence human health and fertility. In particular, specific genetic variants can influence the response to dietary components and nutrient requirements, and conversely, the diet itself is able to modulate gene expression. In this context and the era of precision medicine, nutrigenetic and nutrigenomic studies offer significant opportunities to improve the prevention of metabolic disturbances, such as Type 2 diabetes, gestational diabetes, hypertension, and cardiovascular diseases, even with transgenerational effects. The present review takes into account the interactions between diet, genes and human health, and provides an overview of the role of nutrigenetics, nutrigenomics and epigenetics in the prevention of non-communicable diseases. Moreover, we focus our attention on the mechanism of intergenerational or transgenerational transmission of the susceptibility to metabolic disturbances, and underline that the reversibility of epigenetic modifications through dietary intervention could counteract perturbations induced by lifestyle and environmental factors.

scholarly journals Chemistry-Assisted Proteomic Profiling of O-GlcNAcylation

2021 ◽  
Vol 9 ◽  
Author(s):  
Qiang Zhu ◽  
Wen Yi
Keyword(s):  
Mass Spectrometry ◽  
Neurodegenerative Diseases ◽  
Normal Cell ◽  
Functional Role ◽  
Human Diseases ◽  
Cell Physiology ◽  
Proteomic Profiling ◽  
Detection Technologies

The modification on proteins with O-linked N-acetyl-β-D-glucosamine (O-GlcNAcylation) is essential for normal cell physiology. Dysregulation of O-GlcNAcylation leads to many human diseases, such as cancer, diabetes and neurodegenerative diseases. Recently, the functional role of O-GlcNAcylation in different physiological states has been elucidated due to the booming detection technologies. Chemical approaches for the enrichment of O-GlcNAcylated proteins combined with mass spectrometry-based proteomics enable the profiling of protein O-GlcNAcylation in a system-wide level. In this review, we summarize recent progresses on the enrichment and proteomic profiling of protein O-GlcNAcylation.

scholarly journals Role of Nutrient and Energy Sensors in the Development of Type 2 Diabetes

2021 ◽  
Author(s):  
Verónica Hurtado-Carneiro ◽  
Ana Pérez-García ◽  
Elvira Álvarez ◽  
Carmen Sanz
Keyword(s):  
Type 2 Diabetes ◽  
Nutrient Availability ◽  
Energy Demand ◽  
Metabolic Response ◽  
Whole Body ◽  
Key Factor ◽  
Control Food ◽  
Control Food Intake

Cell survival depends on the constant challenge to match energy demands with nutrient availability. This process is mediated through a highly conserved network of metabolic fuel sensors that orchestrate both a cellular and whole-body energy balance. A mismatch between cellular energy demand and nutrient availability is a key factor in the development of type 2 diabetes, obesity, metabolic syndrome, and other associated pathologies; thus, understanding the fundamental mechanisms by which cells detect nutrient availability and energy demand may lead to the development of new treatments. This chapter reviews the role of the sensor PASK (protein kinase with PAS domain), analyzing its role in the mechanisms of adaptation to nutrient availability and the metabolic response in different organs (liver, hypothalamus) actively cooperating to control food intake, maintain glycaemia homeostasis, and prevent insulin resistance and weight gain.

scholarly journals Seipin-Mediated Contacts as Gatekeepers of Lipid Flux at the Endoplasmic Reticulum–Lipid Droplet Nexus 

Contact ◽  
2020 ◽  
Vol 3 ◽  
pp. 251525642094582
Author(s):  
Veijo T. Salo ◽  
Maarit Hölttä-Vuori ◽  
Elina Ikonen
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Metabolism ◽  
Recent Work ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Intimate Relationship

Lipid droplets (LDs) are dynamic cellular hubs of lipid metabolism. While LDs contact a plethora of organelles, they have the most intimate relationship with the endoplasmic reticulum (ER). Indeed, LDs are initially assembled at specialized ER subdomains, and recent work has unraveled an increasing array of proteins regulating ER-LD contacts. Among these, seipin, a highly conserved lipodystrophy protein critical for LD growth and adipogenesis, deserves special attention. Here, we review recent insights into the role of seipin in LD biogenesis and as a regulator of ER-LD contacts. These studies have also highlighted the evolving concept of ER and LDs as a functional continuum for lipid partitioning and pinpointed a role for seipin at the ER-LD nexus in controlling lipid flux between these compartments.

scholarly journals Lkb1 suppresses amino acid-driven gluconeogenesis in the liver

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Pierre-Alexandre Just ◽  
Sara Charawi ◽  
Raphaël G. P. Denis ◽  
Mathilde Savall ◽  
Massiré Traore ◽  
...  
Keyword(s):  
Amino Acid ◽  
Glucose Production ◽  
Whole Body ◽  
Postprandial Period ◽  
Key Factor ◽  
Liver Kinase B1 ◽  
Whole Body Metabolism ◽  
Specific Deletion

AbstractExcessive glucose production by the liver is a key factor in the hyperglycemia observed in type 2 diabetes mellitus (T2DM). Here, we highlight a novel role of liver kinase B1 (Lkb1) in this regulation. We show that mice with a hepatocyte-specific deletion of Lkb1 have higher levels of hepatic amino acid catabolism, driving gluconeogenesis. This effect is observed during both fasting and the postprandial period, identifying Lkb1 as a critical suppressor of postprandial hepatic gluconeogenesis. Hepatic Lkb1 deletion is associated with major changes in whole-body metabolism, leading to a lower lean body mass and, in the longer term, sarcopenia and cachexia, as a consequence of the diversion of amino acids to liver metabolism at the expense of muscle. Using genetic, proteomic and pharmacological approaches, we identify the aminotransferases and specifically Agxt as effectors of the suppressor function of Lkb1 in amino acid-driven gluconeogenesis.

scholarly journals The yeast FIT2 homologs are necessary to maintain cellular proteostasis and membrane lipid homeostasis

2020 ◽  
Vol 133 (21) ◽  
pp. jcs248526 ◽  
Author(s):  
Wei Sheng Yap ◽  
Peter Shyu ◽  
Maria Laura Gaspar ◽  
Stephen A. Jesch ◽  
Charlie Marvalim ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Lipid Droplets ◽  
Membrane Lipid ◽  
Model System ◽  
Lipid Homeostasis ◽  
Compensatory Mechanism ◽  
Unfolded Protein ◽  
Protein Response

ABSTRACTLipid droplets (LDs) are implicated in conditions of lipid and protein dysregulation. The fat storage-inducing transmembrane (FIT; also known as FITM) family induces LD formation. Here, we establish a model system to study the role of the Saccharomyces cerevisiae FIT homologues (ScFIT), SCS3 and YFT2, in the proteostasis and stress response pathways. While LD biogenesis and basal endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) remain unaltered in ScFIT mutants, SCS3 was found to be essential for proper stress-induced UPR activation and for viability in the absence of the sole yeast UPR transducer IRE1. Owing to not having a functional UPR, cells with mutated SCS3 exhibited an accumulation of triacylglycerol within the ER along with aberrant LD morphology, suggesting that there is a UPR-dependent compensatory mechanism that acts to mitigate lack of SCS3. Additionally, SCS3 was necessary to maintain phospholipid homeostasis. Strikingly, global protein ubiquitylation and the turnover of both ER and cytoplasmic misfolded proteins is impaired in ScFITΔ cells, while a screen for interacting partners of Scs3 identifies components of the proteostatic machinery as putative targets. Together, our data support a model where ScFITs play an important role in lipid metabolism and proteostasis beyond their defined roles in LD biogenesis.This article has an associated First Person interview with the first author of the paper.

scholarly journals The role of adipokines in β-cell failure of type 2 diabetes

2012 ◽  
Vol 216 (1) ◽  
pp. T37-T45 ◽  
Author(s):  
Simon J Dunmore ◽  
James E P Brown
Keyword(s):  
Type 2 Diabetes ◽  
Β Cells ◽  
Β Cell ◽  
Beneficial Effects ◽  
Published Evidence ◽  
Key Factor ◽  
Excessive Adiposity ◽  
Factor Α

β-Cell failure coupled with insulin resistance is a key factor in the development of type 2 diabetes. Changes in circulating levels of adipokines, factors released from adipose tissue, form a significant link between excessive adiposity in obesity and both aforementioned factors. In this review, we consider the published evidence for the role of individual adipokines on the function, proliferation, death and failure of β-cells, focusing on those reported to have the most significant effects (leptin, adiponectin, tumour necrosis factor α, resistin, visfatin, dipeptidyl peptidase IV and apelin). It is apparent that some adipokines have beneficial effects whereas others have detrimental properties; the overall contribution to β-cell failure of changed concentrations of adipokines in the blood of obese pre-diabetic subjects will be highly dependent on the balance between these effects and the interactions between the adipokines, which act on the β-cell via a number of intersecting intracellular signalling pathways. We emphasise the importance, and comparative dearth, of studies into the combined effects of adipokines on β-cells.

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