NCBI Summary:
The protein encoded by this gene belongs to the perilipin family, members of which coat intracellular lipid storage droplets. This protein is associated with the lipid globule surface membrane material, and maybe involved in development and maintenance of adipose tissue. However, it is not restricted to adipocytes as previously thought, but is found in a wide range of cultured cell lines, including fibroblasts, endothelial and epithelial cells, and tissues, such as lactating mammary gland, adrenal cortex, Sertoli and Leydig cells, and hepatocytes in alcoholic liver cirrhosis, suggesting that it may serve as a marker of lipid accumulation in diverse cell types and diseases. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Mar 2011]
General function
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Cellular localization
Plasma membrane
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Ovarian function
Oocyte maturation, Early embryo development
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Expression of Perilipin 2 (PLIN2) in Porcine Oocytes During Maturation. Zhang R 2014 et al.
Perilipins have been reported to limit the interaction of lipases with neutral lipids within the droplets, thereby regulating neutral lipid accumulation and utilization. This study aimed to identify the location and expression of PLIN1 and PLIN2 in porcine oocytes during maturation. Quantitative real-time polymerase chain reaction (qRT-PCR), immunostaining and Western blot methods were used to characterize the expression and distribution patterns of PLIN1 and PLIN2 in porcine oocytes. The results showed that PLIN1 was not detectable in porcine oocytes. PLIN2 and BODIPY 493/503-detected neutral lipid droplets appeared identical distribution patterns and extensive colocalization in both GV and MII porcine oocytes. PLIN2 protein expression was higher in GV oocytes than that in MII oocytes (p?Sastre D 2013 et al.
In vitro-produced embryos store high lipid content in cytoplasmic lipid droplets (LD), and reduction or removal of LD has been demonstrated to improve freeze-thaw viability. The Perilipin Adipophilin Tail-interacting Protein of 47 kD (PAT) family of proteins is involved in the formation and regulation of LD in many cell types, but their presence has not been addressed either in cattle oocytes or preimplantation embryos. Therefore, this study aimed to detect the expression of PAT family transcripts ,Perilipin-2 ,PLIN2 and Perilipin-3 ,PLIN3, in immature and in?vitro-matured (IVM) oocytes, and in in?vitro-produced embryos at the stages of two to four cells, eight to 16 cells, morulae (MO), and blastocyst (BL). The expression of PLIN3 was downregulated in response to IVM, and PLIN2 was comparatively more expressed than PLIN3 in IVM oocytes (P < 0.001). During the early stages of embryo development, PLIN2 expression reached its peak at the MO stage (P < 0.001) and decreased again at the BL stage. In contrast, PLIN3 was expressed in low levels during the earliest stages of development, slightly upregulated at the MO stage (P < 0.05), and greatly increased its expression at the BL stage (15-fold; P < 0.001). PLIN3 was comparatively more expressed than PLIN2 during embryo culture in most stages analyzed (P < 0.05), except in eight- to 16-cell embryos. These results indicate that PLIN2 might be involved in the maintenance of lipid stocks necessary to support embryo development after fertilization of IVM oocytes. Also, we hypothesize that PLIN3 is the main PAT protein responsible for stabilization of LD formed in consequence of the acute lipid load seen during embryo development. We confirmed the presence of both PLIN2 and PLIN3 proteins in BL at Day 7 using immunocytochemistry: these PAT proteins colocalized with LD stained with BODIPY. PLIN3 seemed to be more ubiquitously spread out in the cytoplasm than PLIN2, consistent with the pattern seen in adipocytes. These findings suggest that both elderly (bigger) and newly formed (smaller) LD, positive for PLIN2 and PLIN3 respectively, coexist in blastocysts. To our knowledge this is the first report showing that transcripts of the PAT family are present in cattle oocytes and embryos.
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Genomic assessment of human cumulus cell marker genes as predictors of oocyte developmental competence: impact of various experimental factors. Feuerstein P et al. Single embryo transfer (SET) is the most successful way to reduce the frequency of multiple pregnancies following in vitro fertilisation. However, selecting the embryo for SET with the highest chances of pregnancy remains a difficult challenge since morphological and kinetics criteria provide poor prediction of both developmental and implantation ability. Partly through the expression of specific genes, the oocyte-cumulus interaction helps the oocyte to acquire its developmental competence. Our aim was therefore to identify at the level of cumulus cells (CCs) genes related to oocyte developmental competence.
Expression regulated by
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Ovarian localization
Oocyte, Cumulus, Granulosa
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Lipid Droplets and Steroidogenic Cells. Shen WJ et al. (2015) Lipid droplets (LDs) in steroidogenic tissues have a cholesteryl ester (CE) core surrounded by a phospholipid monolayer that is coated with associated proteins. Compared with other tissues, they tend to be smaller in size and more numerous in numbers. These LDs are enriched with PLIN1c, PLIN2 and PLIN3. Both CIDE A and B are found in mouse ovary. Free cholesterol (FC) released upon hormone stimulation from LDs is the preferred source of cholesterol substrate for steroidogenesis, and HSL is the major neutral cholesterol esterase mediating the conversion of CEs to FC. Through the interaction of HSL with vimentin and StAR, FC is translocated to mitochondria for steroid hormone production. Proteomic analyses of LDs isolated from loaded primary ovarian granulosa cells, mouse MLTC-1 Leydig tumor cells and mouse testes revealed LD associated proteins that are actively involved in modulating lipid homeostasis along with a number of steroidogenic enzymes. Microscopy analysis confirmed the localization of many of these proteins to LDs. These studies broaden the role of LDs to include being a platform for functional steroidogenic enzyme activity or as a port for transferring steroidogenic enzymes and/or steroid intermediates, in addition to being a storage depot for CEs.//////////////////
Fatty acid synthesis and oxidation in cumulus cells support oocyte maturation in bovine. Sanchez-Lazo L 2014 et al.
Oocyte meiotic maturation requires energy from various substrates including glucose, amino acids and lipids. Mitochondrial fatty acid (FA) beta-oxidation (FAO) in the oocyte is required for meiotic maturation, which is accompanied by differential expression of numerous genes involved in FA metabolism in surrounding cumulus cells (CC) in vivo. The objective was to elucidate components involved in FA metabolism in CC during oocyte maturation. Twenty-seven genes related to lipogenesis, lipolysis, FA transport and FAO were chosen from comparative transcriptome analysis of bovine CC before and after maturation in vivo. Using real time PCR, 22 were significantly up-regulated at different times of in vitro maturation (IVM) in relation to oocyte meiosis progression from germinal vesicle (GV) breakdown to metaphase-II. Proteins FA synthase, acetyl-Co-A carboxylase, carnitine palmitoyltransferase CPT1, perilipin 2 and FA binding protein FABP3 were detected by western blot and immunolocalized to CC and oocyte cytoplasm, with FABP3 concentrated around oocyte chromatin. By mass spectrometry, CC lipid profiling was shown to be different before and after IVM. FAO inhibitors etomoxir and mildronate dose-dependently decreased oocyte maturation rate in vitro. In terms of viability, cumulus enclosed oocytes were more sensitive to etomoxir than denuded oocytes. In CC, etomoxir (150? M) led to down-regulation of lipogenesis genes and up-regulated lipolysis and FAO genes. Moreover, the number of lipid droplets decreased whereas several lipid species were more abundant compared to non-treated CC after IVM. In conclusion, FA metabolism in CC is important to maintain metabolic homeostasis and may influence meiosis progression and survival of enclosed oocytes.
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Identification of Perilipin-2 as a lipid droplet protein regulated in oocytes during maturation. Yang X et al. Lipid droplet proteins regulate the storage and utilisation of intracellular lipids. Evidence is emerging that oocyte lipid utilisation impacts embryo development, but lipid droplet proteins have not been studied in oocytes. The aim of the present study was to characterise the size and localisation of lipid droplets in mouse oocytes during the periovulatory period and to identify lipid droplet proteins as potential biomarkers of oocyte lipid content. Oocyte lipid droplets, visualised using a novel method of staining cumulus-oocyte complexes (COCs) with BODIPY 493/503, were small and diffuse in oocytes of preovulatory COCs, but larger and more centrally located after maturation in response to ovulatory human chorionic gonadotrophin (hCG) in vivo, or FSH + epidermal growth factor in vitro. Lipid droplet proteins Perilipin, Perilipin-2, cell death-inducing DNA fragmentation factor 45-like effector (CIDE)-A and CIDE-B were detected in the mouse ovary by immunohistochemistry, but only Perilipin-2 was associated with lipid droplets in the oocyte. In COCs, Perilipin-2 mRNA and protein increased in response to ovulatory hCG. IVM failed to induce Perilipin-2 mRNA, yet oocyte lipid content was increased in this context, indicating that Perilipin-2 is not necessarily reflective of relative oocyte lipid content. Thus, Perilipin-2 is a lipid droplet protein in oocytes and its induction in the COC concurrent with dynamic reorganisation of lipid droplets suggests marked changes in lipid utilisation during oocyte maturation.
Follicle stages
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MALDI Mass Spectrometry Imaging of Lipids and Gene Expression Reveals Differences in Fatty Acid Metabolism between Follicular Compartments in Porcine Ovaries. Uzbekova S et al. (2015) In mammals, oocytes develop inside the ovarian follicles; this process is strongly supported by the surrounding follicular environment consisting of cumulus, granulosa and theca cells, and follicular fluid. In the antral follicle, the final stages of oogenesis require large amounts of energy that is produced by follicular cells from substrates including glucose, amino acids and fatty acids (FAs). Since lipid metabolism plays an important role in acquiring oocyte developmental competence, the aim of this study was to investigate site-specificity of lipid metabolism in ovaries by comparing lipid profiles and expression of FA metabolism-related genes in different ovarian compartments. Using MALDI Mass Spectrometry Imaging, images of porcine ovary sections were reconstructed from lipid ion signals for the first time. Cluster analysis of ion spectra revealed differences in spatial distribution of lipid species among ovarian compartments, notably between the follicles and interstitial tissue. Inside the follicles analysis differentiated follicular fluid, granulosa, theca and the oocyte-cumulus complex. Moreover, by transcript quantification using real time PCR, we showed that expression of five key genes in FA metabolism significantly varied between somatic follicular cells (theca, granulosa and cumulus) and the oocyte. In conclusion, lipid metabolism differs between ovarian and follicular compartments.//////////////////