The minimal adipose phenotype of hormone-sensitive lipase (HSL)-null mice suggested that other hormonally responsive lipase(s) were present in adipocytes. Recent studies have characterized a new adipose tissue triglyceride lipase, ATGL/PNPLA2/destnutrin/iPLA2/ TTS2.2 (ATGL). We had previously cloned a novel adipose-enriched transcript by differential screening and recently determined its identity with murine ATGL. We report here on the regulation of ATGL by TNF-␣ and insulin in 3T3-L1 adipocytes and identify ATGL as a target for transcriptional activation by the key adipogenic transcription factor PPAR␥. Insulin at 100 nM resulted in a marked decrease in ATGL transcript that was effectively blocked by inhibitors for PI 3-kinase and p70 ribosomal protein S6 kinase. TNF-␣ treatment decreased ATGL transcript in a time-dependent manner that paralleled TNF-␣ downregulation of PPAR␥ with a maximal decrease noted by 6 h. TNF-␣ effects on ATGL were attenuated by pretreatment with PD-98059, LY-294002, or rapamycin, suggesting involvement of the p44/42 MAP kinase, PI 3-kinase, and p70 ribosomal protein S6 kinase signals. To study transcriptional regulation of ATGL, we cloned 2,979 bp of the murine ATGL 5Ј-flanking region. Compared with promoterless pGL2-Basic, the Ϫ2979/ϩ21 ATGL luciferase construct demonstrated 120-and 40-fold increases in activity in white and brown adipocytes, respectively. Luciferase reporter activities for a series of eight ATGL promoter deletions revealed that the Ϫ928/ϩ21, Ϫ1738/ϩ21, Ϫ1979/ϩ21, and Ϫ2979/ϩ21 constructs were transactivated by PPAR␥. Our findings identify the novel lipase ATGL to be a target gene for TNF-␣ and insulin action in adipocytes and reveal that it is subject to transcriptional control by PPAR␥-mediated signals.

It has been widely acknowledged that non-coding RNAs are master-regulators of genomic functions. However, the significance of the presence of ncRNA within introns has not received proper attention. ncRNA within introns are commonly produced through the post-splicing process and are specific signals of gene transcription events, impacting many other genes and modulating their expression. This study, along with the following discussion, details the association of thousands of ncRNAs—snoRNA, miRNA, siRNA, piRNA and long ncRNA—within human introns. We propose that such an association between human introns and ncRNAs has a pronounced synergistic effect with important implications for fine-tuning gene expression patterns across the entire genome.

MS, Smas CM.Functional analysis of FSP27 protein regions for lipid droplet localization, caspase-dependent apoptosis, and dimerization with CIDEA. Am J Physiol Endocrinol Metab 297: E1395-E1413, 2009. First published October 20, 2009 doi:10.1152/ajpendo.00188.2009.-The adipocytespecific protein FSP27, also known as CIDEC, is one of three cell death-inducing DFF45-like effector (CIDE) proteins. The first known function for CIDEs was promotion of apoptosis upon ectopic expression in mammalian cells. Recent studies in endogenous settings demonstrated key roles for CIDEs in energy metabolism. FSP27 is a lipid droplet-associated protein whose heterologous expression enhances formation of enlarged lipid droplets and is required for unilocular lipid droplets typical of white adipocytes in vivo. Here, we delineate relationships between apoptotic function and lipid droplet localization of FSP27. We demonstrate that ectopic expression of FSP27 induces enlarged lipid droplets in multiple human cell lines, which is indicative that its mechanism involves ubiquitously present, rather than adipocyte-specific, cellular machinery. Furthermore, promotion of lipid droplet formation in HeLa cells via culture in exogenous oleic acid offsets FSP27-mediated apoptosis. Using transient cotransfections and analysis of lipid droplets in HeLa cells stably expressing FSP27, we show that FSP27 does not protect lipid droplets from action of ATGL lipase. Domain mapping with eGFP-FSP27 deletion constructs indicates that lipid droplet localization of FSP27 requires amino acids 174 -192 of its CIDE C domain. The apoptotic mechanism of FSP27, which we show involves caspase-9 and mitochondrial cytochrome c, also requires this 19-amino acid region. Interaction assays determine the FSP27 CIDE C domain complexes with CIDEA, and Western blot reveals that FSP27 protein levels are reduced by coexpression of CIDEA. Overall, our findings demonstrate the function of the FSP27 CIDE C domain and/or regions thereof for apoptosis, lipid droplet localization, and CIDEA interaction.fat-specific protein 27; cell death-inducing DFF45-like effector A; adipose OBESITY AND ITS RELATED COMORBIDITIES are approaching epidemic levels (1, 9). The development of new therapeutic inroads to treat these conditions would be greatly facilitated by a full understanding of lipid homeostasis (35,36). Lipotoxicity is a highly detrimental outcome of the obese state, leading to derangement of cell function and/or cell death in various tissues (34,35,37). White adipocytes present in white adipose tissue are the major site storage of excess energy in the form of triacylglycerol, contained within intracellular lipid droplets (7,38). Efficient storage of excess fatty acids within adipocyte lipid droplets also serves to protect other cells and tissues from their lipotoxic effects (7, 38). Lipid droplets are highly dynamic organelles consisting of a neutral lipid core, a phospholipid monolayer, and a large number of lipid droplet-associated proteins (7, 38). The role for the vast majority ...

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