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Posts Tagged ‘SREBP2 antibody’

SREBP: Gatekeeper of Cholesterol Homeostasis

Monday, July 29th, 2013

SREBP1 (sterol-regulatory-element-binding protein 2) is a basic-helix-loop-helix-leucine zipper (bHLH-ZIP) transcription factor. It regulates sterol and cholesterol homeostasis by controlling enzymes involved in cholesterol synthesis and uptake, e.g. HMG-CoA. The SREBP1 antibody was used in fundamental studies to dissect SREBP1 domains and downstream signaling (1). These studies identified domains for membrane attachment, DNA binding and transcriptional activation of effectors like the sterol regulatory element-1 (SRE-1) and Max, another bHLH-ZIP protein. SREBP1 modulates expression of the transmembrane protein ABCA1 (ATP-binding cassette transporter-A1) that is responsible for managing cellular cholesterol efflux.  ABCA1 mediates transport of lipids between the Golgi body and plasma membrane, as well as cholesterol and phospholipid efflux to the ApoA1 and ApoE apolipoproteins in the formation of high-density lipoprotein (HDL). Work with SREBP1 antibody in liver, adipose tissue, and skeletal muscle studied the involvement of SREBP-1 during fasting and refeeding and found that SREBP-1 is involved not only in lipid metabolism but glucose metabolism and energy homeostasis (2). Researchers have used the SREBP1 antibody to identify genes responsible for transcriptional regulation through both SREBP2 and SREBP1 (3). Biochemical studies with SREBP1 antibody found that   cholesterol regulates the rate-limiting fatty acid synthesis pathway enzyme stearoyl-CoA desaturase (SCD) gene family independently of SREBP-1 maturation (4). The accessory protein Insig-2, found in the endoplasmic reticulum (ER), inhibits the escort of SREBPs to the Golgi in a sterol-dependent fashion (5).  This feedback regulation adds a level of fine-tuning to the cholesterol homeostasis system.

  1. PMID: 8006035
  2. PMID: 15627654
  3. PMID: 7862668
  4. PMID: 12364560
  5. PMID: 12242332

SREBP2: From Cholesterol Homeostasis to Cancer Invasion

Wednesday, June 6th, 2012

Sterol-regulatory-element-binding protein 2 (SREBP2) is a transcription factor that regulates cholesterol homeostasis by controlling enzymes involved in cholesterol synthesis and uptake, e.g. HMG-CoA. Along with another transcription factor LXR, SREBP2 modulates expression of the transmembrane protein ABCA1, which is responsible for managing cellular cholesterol efflux. ABCA1 mediates transport of lipids between the Golgi body and plasma membrane, as well as cholesterol and phospholipid efflux to the ApoA1 and ApoE apolipoproteins in the formation of HDL. Studies with SREBP antibodies have shown that other SREBP family isoforms have different roles in lipid synthesis – SREBP2 however, is relatively specific to cholesterol synthesis1.

Immunocytochemistry/Immunofluorescence: SREBP2 Antibody

Recent work with SREBP antibodies in smooth muscle cells studied the effects of adhesion on HMG-CoA reductase as the rate-limiting step within the cholesterol biosynthesis pathway2. Exciting and new chromatin immunuprecipitation studies with SREBP2 antibody found that cholesterol synthesis signal transduction pathways (like that of SREBP) may have a strong role in cancer invasion3. Specifically, HDAC5 was found to be a downstream SREBP2 target that not only upregulates oxysterol binding proteins but is associated with tumor invasion and poor prognosis in pancreatic cancer patients. miRNAs have been shown to play an important role in cholesterol homeostasis by post-transcriptional regulation of a number of lipid metabolism genes, with SREBP antibody studies showing ABCA1 inhibition through a powerful ntronic miRNA named miR-33 that affects several other lipids 4.

  1. PMID: 15589694
  2. PMID: 19608976
  3. PMID: 20128820
  4. PMID: 20732877

Novus Biologicals offers SREBP2 reagents for your research needs including:

ABCA1 Expression is Down-Regulated by SREBP microRNA

Friday, March 18th, 2011

The ABCA1 (ATP-binding cassette transporter-A1) gene encodes a transmembrane protein, which plays a major role in phospholipid homeostasis by regulating cholesterol efflux from the cell. ABCA1 antibody studies have shown ABCA1 expression is up/down regulated by the transcription factors LXR and SREBP2 respectively. Now, new evidence points to microRNA (mRNA) being integral to SREBP2 down-regulation of ABCA1. We at Novus Biologicals have a large number of LXR, SREBP2 and ABCA1 antibody products in our antibody catalog.

ABCA1 is expressed on the Golgi body and plasma membrane. Expression is regulated by transcription factors in response to alterations in the cholesterol flux. Its role is to mediate transport of lipids between the two expression sites, and to moderate cholesterol and phospholipid efflux to the ApoA1 and ApoE apolipoproteins, for HDL (high-density lipoprotein) formation. The protein is expressed in high levels in the liver, gut and adipose tissue.

Immunocytochemistry/Immunofluorescence: ABCA1 Antibody

SREBP-2 (sterol-regulatory-element-binding protein 2) controls cholesterol homeostasis by upregulation of genes involved in cholesterol synthesis and uptake, e.g. HMG-CoA, while LXR upregulates expression of ABCA1 and other cholesterol efflux genes. Oxysterols (cholesterol derivatives) inhibit SREBP2 activation whilst acting as LXR ligands. ABCA1 antibody studies conducted by J.Wang have suggested SREBP2 controls ABCA1 expression by maintaining a supply of oxysterol ligands for LXR.

Recently, miRNAs have been shown to play an important role in cholesterol homeostasis by post-transcriptional regulation of a number of lipid metabolism genes, with ABCA1 antibody studies demonstrating ABCA1 inhibition by miRNA action. A study conducted in 2010 showed inhibition was achieved by two miRNAs embedded in the SREBP2 host gene. This exciting development has opened new avenues of research for our antibody catalog.

Novus Biologicals offers many ABCA1 reagents for your research needs including: