• Molecules and Cells
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• v.43 no.8
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• pp.686-693
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• 2020

Autophagy is an intracellular degradation system that breaks down damaged organelles or damaged proteins using intracellular lysosomes. Recent studies have also revealed that various forms of selective autophagy play specific physiological roles under different cellular conditions. Lipid droplets, which are mainly found in adipocytes and hepatocytes, are dynamic organelles that store triglycerides and are critical to health. Lipophagy is a type of selective autophagy that targets lipid droplets and is an essential mechanism for maintaining homeostasis of lipid droplets. However, while processes that regulate lipid droplets such as lipolysis and lipogenesis are relatively well known, the major factors that control lipophagy remain largely unknown. This review introduces the underlying mechanism by which lipophagy is induced and regulated, and the current findings on the major roles of lipophagy in physiological and pathological status. These studies will provide basic insights into the function of lipophagy and may be useful for the development of new therapies for lipophagy dysfunction-related diseases.

• Applied Microscopy
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• v.22 no.1
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• pp.15-32
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• 1992

This study was an attempt to investigate and compare the fine structure of small cells in the space of Disse of various animal livers. All animal livers contained small cells with or without lipid droplets and the one with lipid droplet seemed to be more developed and show an abundance of activity in function. The fine structure of the small cells observed in the nonmammals was similar to that of Ito cell in the mammal. The electron density of the small cells was similar to that of other cell types in the same animal liver. The cisternal dilation of rough endoplasmic reticulum and Golgi apparatus was more predominant in the mammalian Ito cells. In the nonmammalian, aquatic vertebrates, however, lysosomes and filaments are much more abundant in the Ito cell and its abundant cytoplasmic processes rich in filaments were usually extended between the parenchymal cells. The disparity in size of organelles and numbers of lipid droplets in the small cells showed a tendency similar to those of other cell types in the same animal. From these results, it is considered that the small cells in the space of Disse is a Ito cell and the Ito cell without lipid droplets differentiates into the one containing lipid droplets according to the characteristics of the different animals respectively, and that the Ito cells in the mammals are more active in metabolic function, while those in the nonmammalian aquatic vertebrates are abundant in support of parenchyme.

• Nutrition Research and Practice
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• v.16 no.3
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• pp.314-329
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• 2022

BACKGROUND/OBJECTIVES: Oocyte lipid droplets play a crucial role in meiosis and embryo development. Biotin is associated with fatty acid synthesis and is the coenzyme for acetyl-CoA carboxylase (ACC). The effects of a biotin deficiency on the oocyte lipid metabolism remain unknown. This study examined the effects of a biotin deficiency and its replenishment on murine 1) oocyte lipid droplet levels, 2) ovary lipid metabolism, and 3) oocyte meiosis. MATERIALS/METHODS: Mice were divided into 3 groups: control, biotin deficient (BD), and recovery groups. The control and BD groups were fed a control diet or BD diet (0.004 or 0 g biotin/kg), respectively. The recovery group mice were fed a BD diet until day 21, and were then fed the control diet from days 22 to 64. This study then quantified the oocyte lipid droplet levels, assessed the oocyte mitochondrial function, and examined the ability of oocytes to undergo meiosis. Ovarian phosphorylated ACC (p-ACC), lipogenesis, β-oxidation, and ATP production-related genes were evaluated. RESULTS: The BD group showed a decrease in lipid droplets and mitochondrial membrane potential and increased p-ACC levels. In the recovery group, the hepatic biotin concentration, ovarian p-ACC levels, and mitochondrial membrane potential were restored to the control group levels. On the other hand, the quantity of lipid droplets in the recovery group was not restored to the control levels. Furthermore, the percentage of oocytes with meiotic abnormalities was higher in the recovery group than in the control group. CONCLUSIONS: A biotin deficiency reduced the oocyte lipid droplet levels by downregulating lipogenesis. The decreased lipid droplets and increased oocyte meiosis failure were not fully restored, even though the biotin nutrition status and gene expression of lipid metabolism was resumed. These results suggest that a biotin deficiency remains robust and can be long-lasting. Biotin might play a crucial role in maintaining the oocyte quality.

• Journal of Korean Neurosurgical Society
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• v.65 no.3
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• pp.430-438
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• 2022

Objective : Dermoid cysts are uncommon in spinal cord tumors, and the phenomenon of their spontaneous rupture into the syrinx cavity is quite rare. We aimed to analyze the imaging characteristics and etiologies, and propose some surgical strategies, for this uncommon phenomenon. Methods : We retrospectively reviewed 14 cases with spinal dermoid cysts that ruptured into the cervical and thoracic syrinx cavity. There were six male and eight female cases, aged 21 to 46 years, who had lipid droplets in the syrinx cavity from C1 to L3. The dermoid cysts were always located at the conus. Based on patients' complaints, clinical manifestations, and imaging results, we adopted tumor excision and/or syrinx cavity aspiration in one stage or multiple stages. Results : Three patients had only a syrinx cavity aspiration surgery due to a history of dermoid cyst excision. Eight patients had dermoid cyst resection and syrinx cavity aspiration in one stage. One patient was operated upon in two stages due to the development of new symptoms at nine months follow-up. Two patients underwent only tumor resection since they did not show similar symptoms or signs caused by the cervicothoracic syrinx. The axial magnetic resonance imaging indicated that the lipid droplets were always not at the center but were eccentric. The clinical effect was satisfactory during the follow-up period in this group. Conclusion : The lipid droplets filled the spinal syrinx cavity, not entirely confined to the central canal. Based on the chief complaints and associated signs, we adopted different surgical strategies and had satisfactory clinical results.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.242-242
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• 2004

This study was conducted to investigate the effects of various supplements added into maturation medium of immature porcine oocytes on quantity of cytoplasmic lipid droplets(LD), subsequent fertilization and development to the blastocyst stage in vitro. The basic maturation medium was TCM 199 + 1 ㎍/㎖ FSH, 0.57 mM cystein, 10 ng/㎖ EGF and was supplemented various supplements(10% FBS, 10% pFF, 0.4% BSA, 1.0% BSA, 0.4% PVP, 1.0% PVP). (omitted)

• BMB Reports
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• v.50 no.7
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• pp.367-372
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• 2017

Monoacylglycerol acyltransferase 1 (MGAT) is a microsomal enzyme that catalyzes the synthesis of diacylglycerol (DAG) and triacylglycerol (TAG). However, the subcellular localization and catalytic function domain of this enzyme is poorly understood. In this report, we identified that murine MGAT1 localizes to the endoplasmic reticulum (ER) under normal conditions, whereas MGAT1 co-localize to the lipid droplets (LD) under conditions of enriching fatty acids, contributing to TAG synthesis and LD expansion. For the enzyme activity, both the N-terminal transmembrane domain and catalytic HPHG motif are required. We also show that the transmembrane domain of MGAT1 consists of two hydrophobic regions in the N-terminus, and the consensus sequence FLXLXXXn, a putative neutral lipid-binding domain, exists in the first transmembrane domain. Finally, MGAT1 interacts with DGAT2, which serves to synergistically increase the TAG biosynthesis and LD expansion, leading to enhancement of lipid accumulation in the liver and fat.

• Animal cells and systems
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• v.15 no.3
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• pp.211-218
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• 2011

Fragmentation in human pre-implantation embryos has been suggested as the process of apoptosis. We have previously demonstrated a direct relationship between the increased reactive oxygen species (ROS) and apoptosis in human pre-implantation embryos. ROS is known to suppress the function of mitochondria in which steroidogenic acute regulatory protein (StAR) and peripheral-type benzodiazepine receptor (PBR) are presented. Therefore, the purpose of this study was to examine the expression of StAR and PBR in human pre-implantation embryos and to evaluate whether reduction of these proteins is associated with apoptosis. Apoptosis was detected by annexin V-fluorescein isothiocyanate (FITC) and mitochondrial membrane potential was measured by 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-benzimidazolyl-carbocyanine iodide (JC-1). Immunofluorescence staining and Western blotting were applied to examine the expression of StAR and PBR in the embryos. Lipid droplets in the embryos were stained with Oil Red O. The fragmented pre-implantation embryos were stained with annexin V-FITC, but not the normal ones. The mitochondria with active membrane potential were present less in the fragmented embryos compared with the non-fragmented embryos. We also confirmed that both StAR and PBR were expressed in the embryos and their expression levels were lower in the fragmented ones. In addition, the number and size of lipid droplets were increased in the fragmented embryos. The present study provides evidence that reduction of StAR and PBR in human pre-implantation embryos is associated with an increase in the lipid droplets leading to apoptosis.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2004.10a
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• pp.114-114
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• 2004

• Journal of Pharmaceutical Investigation
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• v.37 no.1
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• pp.51-55
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• 2007

Solid lipid nanoparticles (SLNs) have been regarded to behave similar to the vegetable oil emulsions because emulsions of lipid melts are formed before lipid droplets being solidified to turn into SLNs. Compared to lipid emulsion, however, it has been more difficult to obtain stable SLNs and needs more extensive considerations on stabilizer and manufacturing process. In the present study, we tried to prepare phosphatidylcholine-based trymyristin (TM) SLNs using high pressure homogenization method and optimize the manufacturing variables such as homogenization pressure, number of homogenization cycles, cooling temperature, co-stabilizer and freeze-drying with cryoprotectants. Nano-sized TM particles could be Prepared using egg Phosphatidylcholine and pegylated phospholipids ($PEG_{2000}$PE) as stabilizers. Based on the optimization study, the dispersion was manufactured by homogenization under the pressure of 100 MPa for more than 5 cycles, and solidifying the intermediately formed lipid melt droplets by dipping in liquid nitrogen followed by thawing at room temperature. In addition, TM SLNs could be freeze-dried and then redispersed easily without significant particle size changes after freeze drying with 10% and 12.5% sucrose or trehalose. The TM SLNs established in this study can be used as delivery system for drugs and cosmetics.

• The Journal of Traditional Korean Medicine
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• v.15 no.1
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• pp.77-82
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• 2006

Lavandula vera is indispensable member of the herb family, used for perfumes and potpourri. Androgens have profound effects on the physiology of the sebaceous gland. Sebum is secreted due to the effect of androgen, which starts to be secreted at puberty. Using the human sebocyte cell line SZ95. the author investigated the inhibitory effect of Lavandula vera on the lipid production. Light microscopic finding were examined numerous cytoplasmic lipid droplets SZ95 cells by Oil red staining and lipid droplets were increased markedly by testosterone. On the other hand, combined treatment with Lavandula vera and testosterone resulted in a lower lipid droplets than with testosterone alone in a dose-dependent manner. These findings indicate that Lavandula vera acts antagonistically to testosterone and inhibits the lipid synthesis of SZ95 cells at the cellular level.