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1. chinaXiv:201605.01452 [pdf]

Proteomic analysis of murine testes lipid droplets

Wang, Weiyi; Wei, Suning; Su, Xueying; Du, Congkuo; Li, Fengjuan; Geng, Bin; Xu, Guoheng; Li, Linghai; Liu, Pingsheng
Subjects: Biology >> Biophysics

Testicular Leydig cells contain abundant cytoplasmic lipid droplets (LDs) as a cholesteryl-ester store for releasing cholesterols as the precursor substrate for testosterone biosynthesis. Here, we identified the protein composition of testicular LDs purified from adult mice by using mass spectrometry and immunodetection. Among 337 proteins identified, 144 were previously detected in LD proteomes; 44 were confirmed by microscopy. Testicular LDs contained multiple Rab GTPases, chaperones, and proteins involved in glucuronidation, ubiquination and transport, many known to modulate LD formation and LD-related cellular functions. In particular, testicular LDs contained many members of both the perilipin family and classical lipase/esterase superfamily assembled predominately in adipocyte LDs. Thus, testicular LDs might be regulated similar to adipocyte LDs. Remarkably, testicular LDs contained a large number of classical enzymes for biosynthesis and metabolism of cholesterol and hormonal steroids, so steroidogenic reactions might occur on testicular LDs or the steroidogenic enzymes and products could be transferred through testicular LDs. These characteristics differ from the LDs in most other types of cells, so testicular LDs could be an active organelle functionally involved in steroidogenesis.

submitted time 2016-05-12 Hits218Downloads149 Comment 0

2. chinaXiv:201605.01235 [pdf]

Lipid droplet remodeling and interaction with mitochondria in mouse brown adipose tissue during cold treatment

Yu, Jinhai; Zhang, Shuyan; Cui, Liujuan; Na, Huimin; Zhu, Xiaotong; Yang, Fuquan; Liu, Pingsheng; Yu, Jinhai; Na, Huimin; Zhu, Xiaotong; Wang, Weiyi; Xu, Guoheng; Li, Linghai; Christian, Mark; Cui, Liujuan
Subjects: Biology >> Biophysics >> Biochemistry & Molecular Biology

Brown adipose tissue (BAT) maintains animal body temperature by non-shivering thermogenesis, which is through uncoupling protein 1 (UCP1) that uncouples oxidative phosphorylation and utilizes beta-oxidation of fatty acids released from triacylglycerol (TAG) in lipid droplets (LDs). Increasing BAT activity and "browning" other tissues such as white adipose tissue (WAT) can enhance the expenditure of excess stored energy, and in turn reduce prevalence of metabolic diseases. Although many studies have characterized the biology of BAT and brown adipocytes, BAT LDs especially their activation induced by cold exposure remain to be explored. We have isolated LDs from mouse interscapular BAT and characterized the full proteome using mass spectrometry. Both morphological and biochemical experiments showed that the LDs could tightly associate with mitochondria. Under cold treatment mouse BAT started expressing LD structure protein PLIN-2/ADRP and increased expression of PLIN1 Both hormone sensitive lipase (HSL) and adipose TAG lipase (ATGL) were increased in LDs. In addition, isolated BAT LDs showed increased levels of the mitochondrial protein UCP1, and prolonged cold exposure could stimulate BAT mitochondrial cristae biogenesis. These changes were in agreement with the data from transcriptional analysis. Our results provide the BAT LD proteome for the first time and show that BAT LDs facilitate heat production by coupling increasing TAG hydrolysis through recruitment of ATGL and HSL to the organelle and expression of another LD resident protein PLIN2/ADRP, as well as by tightly associating with activated mitochondria. These findings will benefit the study of BAT activation and the interaction between LDs and mitochondria. (C) 2015 Elsevier B.V. All rights reserved.

submitted time 2016-05-11 Hits400Downloads242 Comment 0

3. chinaXiv:201605.00723 [pdf]

Comparative proteomics reveals abnormal binding of ATGL and dysferlin on lipid droplets from pressure overload-induced dysfunctional rat hearts

Li, Linghai; Zhang, Huina; Li, Linghai; Zhang, Huina; Wang, Jifeng; Zhang, Shuyan; Xu, Shimeng; Shu, Qingbo; Yang, Fuquan; Liu, Pingsheng; Wang, Weiyi; Hong, Yun; Zheng, Min; Xu, Shimeng; Shu, Qingbo; Li, Juanfen; Qian, Zongjie;
Subjects: Biology >> Biophysics

Excessive retention of neutral lipids in cardiac lipid droplets (LDs) is a common observation in cardiomyopathy. Thus, the systematic investigation of the cardiac LD proteome will help to dissect the underlying mechanisms linking cardiac steatosis and myocardial dysfunction. Here, after isolation of LDs from normal and dysfunctional Sprague-Dawley rat hearts, we identified 752 heart-associated LD proteins using iTRAQ quantitative proteomic method, including 451 proteins previously unreported on LDs. The most noteworthy finding was the identification of the membrane resealing protein, dysferlin. An analysis of dysferlin truncation mutants indicated that its C2 domain was responsible for its LD localization. Quantitative proteomic results further determined that 27 proteins were increased and 16 proteins were decreased in LDs from post pressure overload-induced dysfunctional hearts, compared with normal hearts. Notably, adipose triacylglycerol lipase (ATGL) was dramatically decreased and dysferlin was substantially increased on dysfunctional cardiac LDs. This study for the first time reveals the dataset of the heart LD proteome in healthy tissue and the variation of it under cardiac dysfunction. These findings highlight an association between the altered LD protein localization of dysferlin and ATGL and myocardial dysfunction.

submitted time 2016-05-05 Hits364Downloads215 Comment 0

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