Biology:Perilipin-2
 Generic protein structure example |
Adipose differentiation-related protein, also known as perilipin 2 , ADRP or adipophilin, is a protein which belongs from PAT family of cytoplasmic lipid droplet(CLD) binding protein.[1] In humans it is encoded by the ADFP gene.[2] This protein surrounds the lipid droplet along with phospholipids and are involved in assisting the storage of neutral lipids within the lipid droplets.[3]
Discovery
The adipose differentiation related protein (ADRP) was first characterized as an mRNA molecule that express early in adipocyte differentiation.[4] The full length cDNA was cloned by rapid amplification of cDNA ends method and sequence analysis results in a protein with 425 amino acids that is unique and similar sequences had not previously been reported.[4]
Gene location
In humans, the gene for adipose differentiation related protein is located at short p arm of chromosome 9 at region 22 band 1 from base pair 19108391 to 19127606 (GRCh38.p7) (map).[5]
Protein structure
The proposed models for adipose differentiation related protein (perilipin 2) is maintained by the protein model portal.[6] It is based on homology modelling and no models were found with greater than 90 percent homology. Perlipin 2 has three different functional domains . 1-115 amino acid sequences at N-terminal is highly similar with other perlipin family proteins and is required for stabilization of lipid droplets, 103-215 mid- region is needed for binding at lipid droplets while the C-terminal sequence from 220-437 forms four helix bundles.[7]
Function
Perilipin 2 was thought to be expressed only in adipose tissues previously.[8] However, later on it was found to be expressed in all types of cells including many non-adipose tissues.[8] The function of perilipin 2 involves the formation of lipid droplets, formation of fatty liver by increasing uptake of fatty acids etc. Decreased expression of perilipin 2 decreases the fatty liver while increase expression of perilipin is associated with several metabolic diseases like type 2 diabetes, insulin resistance, heart diseases. Moreover, its expression was also found to be linked with other age related diseases.[3] This protein is associated with the globule surface membrane material and is major constituent of the globule surface. Increase in mRNA levels is one of the earliest indications of adipocyte differentiation.[2]
Pre-adipocytes are undifferentiated fibroblasts that can be stimulated to form adipocytes. Studies have shed light into potential molecular mechanisms in the fate determination of pre-adipocytes although the exact lineage of adipocyte is still unclear.[9]
Mutation
In humans, a substitution mutation at the C-terminal region of perlipin 2 was shown to affect both the structure and function of the protein.[7] At 251 position , serine residue was substituted by proline which results in the disruption of predicted alpha helical structure of the protein as well as reduction in the plasma triglycerides and lipolysis.[10] Thus, mutation in perlipin 2 may influence the development of different human metabolic diseases.
In vitro and animal studies
Metabolic disorders and liver diseases
Conditions like obesity, type 2 diabetes are related with metabolic disorders. It involves increase accumulation of lipid due to impaired fatty acid metabolism. Alcoholic liver diseases and non-alcoholic fatty liver disease are two types of conditions associated with liver lipid accumulation.[11] Obesity is related with increase accumulation of lipid droplets in non-adipose tissues causing lipotoxicity. The expression of perlipin 2 at normal level appears necessary to induce obesity in mouse model. Increased activity of perlipin 2 increases the resistance to insulin thereby promoting type 2 diabetes.[11]
Cardiovascular diseases
Age related diseases like atherosclerosis, hypertension accounts many deaths in elderly people.[12] Accumulation of lipid droplets induce the modification of macrophages to foam cells. Lysis of foam cells resulted in Atherosclerotic plaques and such plaques rupture and blocked the thrombotic vessel.[12] Perlipin 2 protein around the macrophages and foam cells was found to play important role in formation of atheroma. Downregulation of perlipin 2 inhibits the lipid droplet accumulation and decreases the likelihood to convert macrophages to foam cells.[13]
Cancer
Another factor which increases the risk for cancer is aging process.[14] Analysis of body fluids like urine and blood from circulation from different types of cancer for example colorectal cancer, Burkitt cancer, lung adenocarcinoma showed increase level of Perlipin 2.[15] Perlipin 2 can also serve as a biomarker for early detection of some type of cancer.[16]
References
- ↑ "Multiple functions encoded by the N-terminal PAT domain of adipophilin". Journal of Cell Science 121 (Pt 17): 2921–9. September 2008. doi:10.1242/jcs.026153. PMID 18697835.
- ↑ 2.0 2.1 "Entrez Gene: ADFP adipose differentiation-related protein". https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=123.
- ↑ 3.0 3.1 "Perilipin 2 and Age-Related Metabolic Diseases: A New Perspective". Trends in Endocrinology and Metabolism 27 (12): 893–903. September 2016. doi:10.1016/j.tem.2016.09.001. PMID 27659144.
- ↑ 4.0 4.1 "Isolation and characterization of a full-length cDNA coding for an adipose differentiation-related protein". Proceedings of the National Academy of Sciences of the United States of America 89 (17): 7856–60. September 1992. doi:10.1073/pnas.89.17.7856. PMID 1518805. Bibcode: 1992PNAS...89.7856J.
- ↑ "Homo sapiens (human) Annotation Release 107 (Current)". https://www.ncbi.nlm.nih.gov/mapview/maps.cgi?taxid=9606&chr=9&query=uid(-1699938614,-1699938061,-1263434864,-2146583539)&QSTR=123%5Bgene%5Fid%5D&maps=gene_set&cmd=focus.
- ↑ "Q99541". UniProt. http://www.proteinmodelportal.org/query/uniprot/Q99541.
- ↑ 7.0 7.1 "The minor allele of the missense polymorphism Ser251Pro in perilipin 2 (PLIN2) disrupts an α-helix, affects lipolysis, and is associated with reduced plasma triglyceride concentration in humans". FASEB J. 27 (8): 3090–9. August 2013. doi:10.1096/fj.13-228759. PMID 23603836.
- ↑ 8.0 8.1 "Adipose differentiation-related protein is an ubiquitously expressed lipid storage droplet-associated protein". Journal of Lipid Research 38 (11): 2249–63. November 1997. doi:10.1016/S0022-2275(20)34939-7. PMID 9392423.
- ↑ "Mathematical modeling of preadipocyte fate determination". Journal of Theoretical Biology 265 (1): 87–94. July 2010. doi:10.1016/j.jtbi.2010.03.047. PMID 20385145. Bibcode: 2010JThBi.265...87C.
- Lay summary in: "Scientists closer to finding what causes the birth of a fat cell". ScienceDaily (Press release). August 18, 2010.
- ↑ "The perilipin 2 (PLIN2) gene Ser251Pro missense mutation is associated with reduced insulin secretion and increased insulin sensitivity in Italian obese subjects". Diabetes Metab. Res. Rev. 32 (6): 550–6. September 2016. doi:10.1002/dmrr.2751. PMID 26443937.
- ↑ 11.0 11.1 "Absence of perilipin 2 prevents hepatic steatosis, glucose intolerance and ceramide accumulation in alcohol-fed mice". PLOS ONE 9 (5): e97118. 2014. doi:10.1371/journal.pone.0097118. PMID 24831094. Bibcode: 2014PLoSO...997118C.
- ↑ 12.0 12.1 "Enhanced atheroprotection and lesion remodelling by targeting the foam cell and increasing plasma cholesterol acceptors". Cardiovascular Research 109 (2): 294–304. February 2016. doi:10.1093/cvr/cvv241. PMID 26487692.
- ↑ "Adipophilin increases triglyceride storage in human macrophages by stimulation of biosynthesis and inhibition of beta-oxidation". FEBS J. 273 (15): 3498–510. August 2006. doi:10.1111/j.1742-4658.2006.05357.x. PMID 16884492.
- ↑ "Identification of adipophilin as a potential plasma biomarker for colorectal cancer using label-free quantitative mass spectrometry and protein microarray". Cancer Epidemiology, Biomarkers & Prevention 20 (10): 2195–203. October 2011. doi:10.1158/1055-9965.EPI-11-0400. PMID 21828233.
- ↑ "Identification of adipophilin as a potential diagnostic tumor marker for lung adenocarcinoma". International Journal of Clinical and Experimental Medicine 7 (4): 1190–6. 2014. PMID 24955208.
- ↑ "Mass spectrometry in cancer biomarker research: a case for immunodepletion of abundant blood-derived proteins from clinical tissue specimens". Biomarkers in Medicine 8 (2): 269–86. 2014. doi:10.2217/bmm.13.101. PMID 24521024.
External links
- Human PLIN2 genome location and PLIN2 gene details page in the UCSC Genome Browser.
Further reading
- "Perilipin 2 improves insulin sensitivity in skeletal muscle despite elevated intramuscular lipid levels". Diabetes 61 (11): 2679–90. November 2012. doi:10.2337/db11-1402. PMID 22807032.
- "Adipocyte differentiation-related protein is secreted into milk as a constituent of milk lipid globule membrane". The Biochemical Journal 320 (3): 1025–30. December 1996. doi:10.1042/bj3201025. PMID 9003395.
- "Adipophilin is a specific marker of lipid accumulation in diverse cell types and diseases". Cell and Tissue Research 294 (2): 309–21. November 1998. doi:10.1007/s004410051181. PMID 9799447.
- "Role of adipocyte differentiation-related protein in surfactant phospholipid synthesis by type II cells". American Journal of Physiology. Lung Cellular and Molecular Physiology 283 (2): L288–96. August 2002. doi:10.1152/ajplung.00204.2001. PMID 12114189.
- "Mitogen-inducible gene 6 (MIG-6), adipophilin and tuftelin are inducible by hypoxia". FEBS Letters 530 (1–3): 186–90. October 2002. doi:10.1016/S0014-5793(02)03475-0. PMID 12387890.
- "Live cell analysis and targeting of the lipid droplet-binding adipocyte differentiation-related protein". The Journal of Biological Chemistry 278 (18): 15998–6007. May 2003. doi:10.1074/jbc.M211289200. PMID 12591929.
- "The lipid droplet-associated protein adipophilin is expressed in human trophoblasts and is regulated by peroxisomal proliferator-activated receptor-gamma/retinoid X receptor". The Journal of Clinical Endocrinology and Metabolism 88 (12): 6056–62. December 2003. doi:10.1210/jc.2003-030628. PMID 14671211.
- "Adipophilin enhances lipid accumulation and prevents lipid efflux from THP-1 macrophages: potential role in atherogenesis". Arteriosclerosis, Thrombosis, and Vascular Biology 24 (3): 504–10. March 2004. doi:10.1161/01.ATV.0000115638.27381.97. PMID 14707038.
- "ADRP is dissociated from lipid droplets by ARF1-dependent mechanism". Biochemical and Biophysical Research Communications 322 (3): 957–65. September 2004. doi:10.1016/j.bbrc.2004.08.010. PMID 15336557.
- "Spatial integration of TIP47 and adipophilin in macrophage lipid bodies". The Journal of Biological Chemistry 280 (7): 5789–94. February 2005. doi:10.1074/jbc.M407194200. PMID 15545278.
- "ADRP/adipophilin is degraded through the proteasome-dependent pathway during regression of lipid-storing cells". Journal of Lipid Research 47 (1): 87–98. January 2006. doi:10.1194/jlr.M500170-JLR200. PMID 16230742.
- "Regulation of ADRP expression by long-chain polyunsaturated fatty acids in BeWo cells, a human placental choriocarcinoma cell line". Journal of Lipid Research 47 (4): 815–23. April 2006. doi:10.1194/jlr.M500527-JLR200. PMID 16391323.
- "PPARalpha activators and fasting induce the expression of adipose differentiation-related protein in liver". Journal of Lipid Research 47 (5): 931–43. May 2006. doi:10.1194/jlr.M500459-JLR200. PMID 16489205.
- "Recruitment of TIP47 to lipid droplets is controlled by the putative hydrophobic cleft". Biochemical and Biophysical Research Communications 347 (1): 279–87. August 2006. doi:10.1016/j.bbrc.2006.06.074. PMID 16808905.
- "Role of adipose differentiation-related protein in lung surfactant production: a reassessment". Journal of Lipid Research 47 (11): 2367–73. November 2006. doi:10.1194/jlr.M600157-JLR200. PMID 16936283.
- "Expression of adipose differentiation-related protein: a predictor of cancer-specific survival in clear cell renal carcinoma". Clinical Cancer Research 13 (1): 152–60. January 2007. doi:10.1158/1078-0432.CCR-06-1877. PMID 17200350.
- "Predominance of a proinflammatory phenotype in monocyte-derived macrophages from subjects with low plasma HDL-cholesterol". Arteriosclerosis, Thrombosis, and Vascular Biology 27 (5): 1115–22. May 2007. doi:10.1161/ATVBAHA.106.138990. PMID 17322100.
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