Silencing Acetyl-CoA carboxylase A (ACACA) and Sterol Regulatory Element-binding Protein 1 (SREBP1) Genes Through RNAi Reduce Cholesterol Content in Serum and Eggs of Transgenic Chicken

2021 ◽  
Author(s):  
Athe Rajendra Prasad ◽  
Tarun Bhattacharya ◽  
RN Chatterjee ◽  
D Divya ◽  
SK Bhanja ◽  
...  
Keyword(s):  
Total Cholesterol ◽  
Biosynthetic Pathway ◽  
Ldl Cholesterol ◽  
De Novo ◽  
Regulatory Element ◽  
Cholesterol Content ◽  
Acetyl Coa Carboxylase ◽  
Transgenic Chicken ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

Abstract Cholesterol is synthesized in chicken through de novo lipid biosynthetic pathway where two most important genes viz. SREBP1 and ACACA play immense role. To minimize cholesterol synthesis, RNAi approach was adopted and accordingly, we developed transgenic chicken possessing ACACA and SREBP1 shRNA constructs, which showed lower level of ACACA and SREBP1 in serum. The serum total cholesterol and LDL cholesterol was significantly (P<0.05) lower by 26.8 and 31.3%, and 56.3 and 26.4%, respectively in ACACA and SREBP1 transgenic birds compared to the control. The egg total cholesterol and LDL cholesterol content was significantly (P<0.05) lower in both ACACA and SREBP1 transgenic birds by 14.3 and 13.2%, and 10.3 and 13.6%, respectively compared to the control. It is concluded that the protocol was perfected to develop transgenic chicken through RNAi for knocking down the expression of ACACA and SREBP1 proteins, which minimized the cholesterol and triglycerides contents in serum and eggs.

scholarly journals SCAP/SREBP pathway is required for the full steroidogenic response to cyclic AMP

2016 ◽  
Vol 113 (38) ◽  
pp. E5685-E5693 ◽  
Author(s):  
Masami Shimizu-Albergine ◽  
Brian Van Yserloo ◽  
Martin G. Golkowski ◽  
Shao-En Ong ◽  
Joseph A. Beavo ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Leydig Cells ◽  
De Novo ◽  
Regulatory Element ◽  
De Novo Synthesis ◽  
Intracellular Lipid ◽  
Element Binding Protein ◽  
Short Palindromic Repeat ◽  
Sterol Regulatory Element

Luteinizing hormone (LH) stimulates steroidogenesis largely through a surge in cyclic AMP (cAMP). Steroidogenic rates are also critically dependent on the availability of cholesterol at mitochondrial sites of synthesis. This cholesterol is provided by cellular uptake of lipoproteins, mobilization of intracellular lipid, and de novo synthesis. Whether and how these pathways are coordinated by cAMP are poorly understood. Recent phosphoproteomic analyses of cAMP-dependent phosphorylation sites in MA10 Leydig cells suggested that cAMP regulates multiple steps in these processes, including activation of the SCAP/SREBP pathway. SCAP [sterol-regulatory element-binding protein (SREBP) cleavage-activating protein] acts as a cholesterol sensor responsible for regulating intracellular cholesterol balance. Its role in cAMP-mediated control of steroidogenesis has not been explored. We used two CRISPR (clustered regularly interspaced short palindromic repeat)-Cas9 (CRISPR associated protein 9) knockout approaches to test the role of SCAP in steroidogenesis. Our results demonstrate that SCAP is required for progesterone production induced by concurrent inhibition of the cAMP phosphodiesterases PDE4 and PDE8. These inhibitors increased SCAP phosphorylation, SREBP2 activation, and subsequent expression of cholesterol biosynthetic genes, whereas SCAP deficiency largely prevented these effects. Reexpression of SCAP in SCAP-deficient cells restored SREBP2 protein expression and partially restored steroidogenic responses, confirming the requirement of SCAP–SREBP2 in steroidogenesis. Inhibitors of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase and isoprenylation attenuated, whereas exogenously provided cholesterol augmented, PDE inhibitor-induced steroidogenesis, suggesting that the cholesterol substrate needed for steroidogenesis is provided by both de novo synthesis and isoprenylation-dependent mechanisms. Overall, these results demonstrate a novel role for LH/cAMP in SCAP/SREBP activation and subsequent regulation of steroidogenesis.

scholarly journals Sterol Regulatory Element Binding Protein Regulates the Expression and Metabolic Functions of Wild-Type and OncogenicIDH1

2016 ◽  
Vol 36 (18) ◽  
pp. 2384-2395 ◽  
Author(s):  
Stéphane J. H. Ricoult ◽  
Christian C. Dibble ◽  
John M. Asara ◽  
Brendan D. Manning
Keyword(s):  
Carbon Flux ◽  
De Novo ◽  
Binding Protein ◽  
Regulatory Element ◽  
Lipid Synthesis ◽  
Reducing Power ◽  
Isocitrate Dehydrogenase 1 ◽  
Metabolic Functions ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

Sterol regulatory element binding protein (SREBP) is a major transcriptional regulator of the enzymes underlyingde novolipid synthesis. However, little is known about the SREBP-mediated control of processes that indirectly support lipogenesis, for instance, by supplying reducing power in the form of NAPDH or directing carbon flux into lipid precursors. Here, we characterize isocitrate dehydrogenase 1 (IDH1) as a transcriptional target of SREBP across a spectrum of cancer cell lines and human cancers. IDH1 promotes the synthesis of lipids specifically from glutamine-derived carbons. Neomorphic mutations in IDH1 occur frequently in certain cancers, leading to the production of the oncometabolite 2-hydroxyglutarate (2-HG). We found that SREBP induces the expression of oncogenic IDH1 and influences 2-HG production from glucose. Treatment of cells with 25-hydroxycholesterol or statins, which respectively inhibit or activate SREBP, further supports SREBP-mediated regulation of IDH1 and, in cells with oncogenic IDH1, carbon flux into 2-HG.

scholarly journals Oleanolic Acid Diminishes Liquid Fructose-Induced Fatty Liver in Rats: Role of Modulation of Hepatic Sterol Regulatory Element-Binding Protein-1c-Mediated Expression of Genes Responsible for De Novo Fatty Acid Synthesis

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Changjin Liu ◽  
Ying Li ◽  
Guowei Zuo ◽  
Wenchun Xu ◽  
Huanqing Gao ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Target Genes ◽  
Nuclear Protein ◽  
De Novo ◽  
Binding Protein ◽  
Regulatory Element ◽  
Acid Synthesis ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

Oleanolic acid (OA), contained in more than 1620 plants and as an aglycone precursor for naturally occurred and synthesized triterpenoid saponins, is used in China for liver disorders in humans. However, the underlying liver-protecting mechanisms remain largely unknown. Here, we found that treatment of rats with OA (25 mg/kg/day, gavage, once daily) over 10 weeks diminished liquid fructose-induced excess hepatic triglyceride accumulation without effect on total energy intake. Attenuation of the increased vacuolization and Oil Red O staining area was evident on histological examination of liver in OA-treated rats. Hepatic gene expression profile demonstrated that OA suppressed fructose-stimulated overexpression of sterol regulatory element-binding protein-(SREBP-) 1/1c mRNA and nuclear protein. In accord, overexpression of SREBP-1c-responsive genes responsible for fatty acid synthesis was also downregulated. In contrast, overexpressed nuclear protein of carbohydrate response element-binding protein and its target genes liver pyruvate kinase and microsomal triglyceride transfer protein were not altered. Additionally, OA did not affect expression of peroxisome proliferator-activated receptor-gamma- and -alpha and their target genes. It is concluded that modulation of hepatic SREBP-1c-mediated expression of the genes responsible for de novo fatty acid synthesis plays a pivotal role in OA-elicited diminishment of fructose-induced fatty liver in rats.

scholarly journals Effectors of Rapid Homeostatic Responses of Endoplasmic Reticulum Cholesterol and 3-Hydroxy-3-methylglutaryl-CoA Reductase

2007 ◽  
Vol 283 (3) ◽  
pp. 1445-1455 ◽  
Author(s):  
Yvonne Lange ◽  
Daniel S. Ory ◽  
Jin Ye ◽  
Michael H. Lanier ◽  
Fong-Fu Hsu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Endoplasmic Reticulum ◽  
Regulatory Element ◽  
Cholesterol Content ◽  
Cholesterol Levels ◽  
Element Binding Protein ◽  
Sterol Regulatory Element ◽  
Hmgr Activity ◽  
Coa Reductase ◽  
Cholesterol Precursors

The cholesterol content of the endoplasmic reticulum (ER) and the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) imbedded therein respond homeostatically within minutes to changes in the level of plasma membrane cholesterol. We have now examined the roles of sterol regulatory element-binding protein (SREBP)-dependent gene expression, side chain oxysterol biosynthesis, and cholesterol precursors in the short term regulation of ER cholesterol levels and HMGR activity. We found that SREBP-dependent gene expression is not required for the response to changes in cell cholesterol of either the pool of ER cholesterol or the rate of cholesterol esterification. It was also found that the acute proteolytic inactivation of HMGR triggered by cholesterol loading required the conversion of cholesterol to 27-hydroxycholesterol. High levels of exogenous 24,25-dihydrolanosterol drove the inactivation of HMGR; lanosterol did not. However, purging endogenous 24,25-dihydrolanosterol, lanosterol, and other biosynthetic sterol intermediates by treating cells with NB-598 did not greatly affect either the setting of their ER cholesterol pool or the inactivation of their HMGR. In summary, neither SREBP-regulated genes nor 27-hydroxycholesterol is involved in setting the ER cholesterol pool. On the other hand, 27-hydroxycholesterol, rather than cholesterol itself or biosynthetic precursors of cholesterol, stimulates the rapid inactivation of HMGR in response to high levels of cholesterol.

scholarly journals 4β-hydroxycholesterol is a pro-lipogenic factor that promotes SREBP1c expression and activity through Liver X-receptor

2020 ◽  
Author(s):  
Ofer Moldavski ◽  
Peter-James H. Zushin ◽  
Charles A. Berdan ◽  
Robert J. Van Eijkeren ◽  
Xuntian Jiang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
De Novo ◽  
Regulatory Element ◽  
Liver X Receptor ◽  
De Novo Lipogenesis ◽  
Primary Hepatocytes ◽  
Element Binding Protein ◽  
Sterol Regulatory Element ◽  
Derivatives Of ◽  
Oxidized Derivatives Of Cholesterol

Oxysterols are oxidized derivatives of cholesterol that play signaling roles in lipid biosynthesis and homeostasis. Here we show that 4β-hydroxycholesterol (4β-HC), a liver and serum abundant oxysterol of poorly defined function, is a potent and selective inducer of the master lipogenic transcription factor, Sterol Regulatory Element Binding Protein 1c (SREBP1c), but not the related steroidogenic transcription factor SREBP2. Mechanistically, 4β-HC acts as a putative agonist for Liver X receptor (LXR), a sterol sensor and transcriptional regulator previously linked to SREBP1c activation. Unique among the oxysterol agonists of LXR, 4β-HC induced expression of the lipogenic program downstream of SREBP1c, and triggered de novo lipogenesis both in primary hepatocytes and in mouse liver. 4β-HC-acted in parallel to insulin-PI3K-dependent signaling to stimulate triglyceride synthesis and lipid droplet accumulation. Thus, 4β-HC is an endogenous regulator of de novo lipogenesis through the LXR-SREBP1c axis.

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