A Role for Sp1 in Transcriptional Regulation of Phosphatidylethanolamine N-Methyltransferase in Liver and 3T3-L1 Adipocytes

Cole, Laura K.; Vance, Dennis E.

doi:10.1074/jbc.m110.109843

Cited by 25 publications

(20 citation statements)

References 58 publications

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“…High Fat Challenge Induces PEMT Expression in Adipose Tissue-Recent results have demonstrated that PEMT expression in 3T3-L1 adipocytes gradually increases in a time-dependent manner during adipocyte differentiation, starting at day 5 and reaching a maximum at day 7 (40). Consistent with these findings, Fig.…”

Section: Ld Monolayer Compared With Cellular Membranes Contains Pc supporting

confidence: 80%

“…7A). In line with a recent report (40), PEMT mRNA levels increased markedly between days 5 and 9 of 3T3-L1 differentiation, whereas the signal was virtually absent from undifferentiated cells (day 0). Expression of PS synthase-1 mRNA, which produces PS by exchange of choline in PC for serine (47), was unchanged at day 5 and was moderately higher at day 9.…”

Section: Regulatory Loop Between Pe-synthesizing and Pe-convertingsupporting

confidence: 77%

“…In liver, about onethird of PC is produced by this reaction (18). Because expression of PEMT has recently been described in differentiating 3T3-L1 adipocytes (40), this pathway was assessed during adipocyte differentiation by measuring the incorporation of [ 14 C]dimethylethanolamine into phosphatidyldimethylethanolamine and PC (Fig. 2C).…”

Section: Phospholipid Pattern Changes Profoundly At the Onset Of Adipmentioning

confidence: 99%

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Sequential Synthesis and Methylation of Phosphatidylethanolamine Promote Lipid Droplet Biosynthesis and Stability in Tissue Culture and in Vivo

Hörl

Wagner

Cole

et al. 2011

Journal of Biological Chemistry

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103

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Triacylglycerols are stored in eukaryotic cells within lipid droplets (LD).The LD core is enwrapped by a phospholipid monolayer with phosphatidylcholine (PC), the major phospholipid, and phosphatidylethanolamine (PE), a minor component. We demonstrate that the onset of LD formation is characterized by a change in cellular PC, PE, and phosphatidylserine (PS). With induction of differentiation of 3T3-L1 fibroblasts into adipocytes, the cellular PC/PE ratio decreased concomitant with LD formation, with the most pronounced decline between confluency and day 5. The mRNA for PS synthase-1 (forms PS from PC) and PS decarboxylase (forms PE from PS) increased after day 5. Activity and protein of PE N-methyltransferase (PEMT), which produces PC by methylation of PE, are absent in 3T3-L1 fibroblasts but were induced at day 5. High fat challenge induced PEMT expression in mouse adipose tissue. PE, produced via PS decarboxylase, was the preferred substrate for methylation to PC. A PEMT-GFP fusion protein decorated the periphery of LD. PEMT knockdown in 3T3-L1 adipocytes correlated with increased basal triacylglycerol hydrolysis. Pemt ؊/؊ mice developed desensitization against adenosine-mediated inhibition of basal hydrolysis in adipose tissue, and adipocyte hypotrophy was observed in Pemt ؊/؊ animals on a high fat diet. Knock-out of PEMT in adipose tissue down-regulated PS synthase-1 mRNA, suggesting coordination between PE supply and converting pathways during LD biosynthesis. We conclude that two consecutive processes not previously related to LD biogenesis, (i) PE production via PS and (ii) PE conversion via PEMT, are implicated in LD formation and stability.Cytosolic neutral lipid droplets (LD) 7 within eukaryotic cells represent intracellular storage compartments for triacylglycerols (TG) and cholesteryl esters to bridge alimentary or metabolic gaps (1). Adipocytes are the body's primary depots for efficient TG storage. Upon defined stimulation of adipocytes (2), fatty acids are released from TG droplets to supply energy or to provide essential components for the synthesis of biological membranes. Given these important functions, LD of all cell types are considered as dynamic organelles that represent fundamental components of intracellular lipid homeostasis (3).It is generally accepted that LD originate from the cytosolic leaflet of the endoplasmic reticulum (ER), contain a core of neutral lipids, and are surrounded by a phospholipid (PL) monolayer (4, 5). The finding that cytosolic LD in adipocytes contain at their periphery minor amounts of ER proteins such as BiP (6) and calnexin might reflect their site of origin in the ER. The primary LD proteins are so-called cage proteins, which not only stabilize LD but also protect their neutral lipid cores from unregulated degradation (7). Several other proteins contributing to the regulation of intracellular vesicle trafficking or targeting (3), and components of the intermediate filament protein machinery, have also been shown to be associated with intracellular LD (8, 9).D...

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Section: Ld Monolayer Compared With Cellular Membranes Contains Pc supporting

confidence: 80%

Section: Regulatory Loop Between Pe-synthesizing and Pe-convertingsupporting

confidence: 77%

Section: Phospholipid Pattern Changes Profoundly At the Onset Of Adipmentioning

confidence: 99%

See 1 more Smart Citation

Sequential Synthesis and Methylation of Phosphatidylethanolamine Promote Lipid Droplet Biosynthesis and Stability in Tissue Culture and in Vivo

Hörl

Wagner

Cole

et al. 2011

Journal of Biological Chemistry

Self Cite

103

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“…Recently, transcriptional regulation of two additional phospholipid biosynthetic genes was explored: phosphatidylethanolamine N-methyltransferase, which methylates phosphatidylethanolamine to generate phosphatidylcholine, and CTP:phosphoethanolamine cytidylyltransferase, which catalyzes the ratelimiting step of phosphatidylethanolamine synthesis via the CDP-ethanolamine pathway. Interestingly, both genes are negatively regulated by Sp1 during cell differentiation (62,63). The present studies identify PSS1 as another phospholipid biosynthetic activity that is transcriptionally regulated.…”

Section: Discussionmentioning

confidence: 74%

N-Myc and SP Regulate Phosphatidylserine Synthase-1 Expression in Brain and Glial Cells

Tasseva¹,

Cole

Vance³

2011

Journal of Biological Chemistry

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Phosphatidylserine (PS) is an essential constituent of biological membranes and plays critical roles in apoptosis and cell signaling. Because no information was available on transcriptional mechanisms that regulate PS biosynthesis in mammalian cells, we investigated the regulation of expression of the mouse PS synthase-1 (Pss1) gene. The Pss1 core promoter was characterized in vitro and in vivo through gel shift and chromatin immunoprecipitation assays. Transcription factor-binding sites, such as a GC-box cluster that binds Sp1/Sp3/Sp4 and N-Myc, and a degenerate E-box motif that interacts with Tal1 and E47, were identified. Pss1 transactivation was higher in brain of neonatal mice than in other tissues, consistent with brain being a major site of expression of Pss1 mRNA and PSS1 activity. Enzymatic assays revealed that PSS1 activity is enriched in primary cortical astrocytes compared with primary cortical neurons. Site-directed mutagenesis of binding sites within the Pss1 promoter demonstrated that Sp and N-Myc synergistically activate Pss1 expression in astrocytes. Chromatin immunoprecipitation indicated that Sp1, Sp3, and Sp4 interact with a common DNA binding site on the promoter. Reduction in levels of Sp1, Sp3, or N-Myc proteins by RNA interference decreased promoter activity. In addition, disruption of Sp/DNA binding with mithramycin significantly reduced Pss1 expression and PSS1 enzymatic activity, underscoring the essential contribution of Sp factors in regulating PSS1 activity. These studies provide the first analysis of mechanisms that regulate expression of a mammalian Pss gene in brain. Phosphatidylserine (PS)2 is an anionic phospholipid that accounts for 5-11% of phospholipids in mammalian cells (reviewed in Ref. 1). PS contributes to the physical properties of membranes and activates signaling enzymes such as protein kinase C (2), diacylglycerol kinase (3), c-Raf-1 protein kinase (4), and nitric-oxide synthase (5). PS also modulates the binding of some ligands to their receptors (6), and intriguingly, the anionic nature of PS targets positively charged proteins to endocytic/phagosomal membranes (7). In the plasma membrane of mammalian cells PS is normally highly enriched in the cytosolic leaflet but becomes exposed on the cell surface during several crucial physiological processes such as initiation of the blood-clotting cascade (reviewed in Ref. 8), sperm maturation (9), and apoptosis (10).In higher eukaryotes, PS is synthesized by a calcium-dependent base-exchange reaction in which the head group of an existing phospholipid is exchanged for L-serine (11). Mammalian cells contain two distinct serine exchange enzymes: PS synthase-1 (PSS1) uses phosphatidylcholine, whereas PS synthase-2 (PSS2) uses phosphatidylethanolamine (12). PSS1 and PSS2 are largely absent from the bulk of endoplasmic reticulum membranes but are highly enriched in mitochondriaassociated membranes (13), a specialized endoplasmic reticulum domain that facilitates PS import into mitochondria for decarboxylation to phosphatidyleth...

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“…In support of this finding, the expression of Sp1 has been shown to decrease upon differentiation of 3T3-L1 preadipocytes. 33) Sp1 belongs to Sp transcription factor family with C 2 H 2 -type zinc finger and is involved in the regulation of the housekeeping genes. 34) IBMX, which is a cAMP phosphodiesterase inhibitor and one of the differentiation inducers, suppressed the expression of Sp1 by increasing the cellular cAMP level.…”

Section: )mentioning

confidence: 99%

Mechanism for Decreased Gene Expression of β4-Galactosyltransferase 5 upon Differentiation of 3T3-L1 Mouse Preadipocytes to Adipocytes

Ishii

Miyauchi

Nitta

et al. 2018

Biological & Pharmaceutical Bulletin

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SummaryUpon differentiation of cells, remarkable changes in the structures of glycans linked to lipids on cell surface have been observed. Lactosylceramide (Lac-Cer) serves as a common precursor for a series of glycosphingolipids with diverse structures. In the present study, we examined the underlying mechanism for the biosynthesis of Lac-Cer upon differentiation of 3T3-L1 mouse preadipocytes to adipocytes. TLC analysis showed that the amounts of Lac-Cer decrease in 3T3-L1 adipocytes compared to 3T3-L1 preadipocytes. In accordance with this change, the gene expression level of β4-galactosyltransferase (β4GalT) 5, which was identified as Lac-Cer synthase, decreased drastically upon differentiation of 3T3-L1preadipocytes. The analysis of the transcriptional mechanism of the β4GalT5 gene demonstrated that the core promoter region is identified between nucleotides -299 and -1 relative to the translational start site. During adipocyte differentiation, the expression levels and promoter activities of the β4GalT5 gene decreased dramatically. Since the Specificity protein 1 (Sp1)-binding sites in the promoter region were critical for the promoter activity, it is suggested that Sp1 plays an important role for the expression of the β4GalT5 gene in 3T3-L1 cells. The gene and protein expression of Sp1 decreased significantly upon differentiation of 3T3-L1 preadipocytes. Taken together, the present study suggest that the expression of the β4GalT5 gene decreases through reduced expression of the Sp1 gene and protein upon differentiation of 3T3-L1 peradipocytes to adipocytes, which may lead to the decreased amounts of Lac-Cer in 3T3-L1 adipocytes.

show abstract

A Role for Sp1 in Transcriptional Regulation of Phosphatidylethanolamine N-Methyltransferase in Liver and 3T3-L1 Adipocytes

Cited by 25 publications

References 58 publications

Sequential Synthesis and Methylation of Phosphatidylethanolamine Promote Lipid Droplet Biosynthesis and Stability in Tissue Culture and in Vivo

Sequential Synthesis and Methylation of Phosphatidylethanolamine Promote Lipid Droplet Biosynthesis and Stability in Tissue Culture and in Vivo

N-Myc and SP Regulate Phosphatidylserine Synthase-1 Expression in Brain and Glial Cells

Mechanism for Decreased Gene Expression of β4-Galactosyltransferase 5 upon Differentiation of 3T3-L1 Mouse Preadipocytes to Adipocytes

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