Inhibition of human 3-hydroxy-3-methylglutaryl CoA reductase by peptides leading to cholesterol homeostasis through SREBP2 pathway in HepG2 cells.

Authors:
Varun Kumar
Varun Kumar
Jaypee University of Information Technology
Waknaghat | India
P Sharma
P Sharma
University of Houston
United States
S Sharma
S Sharma
Rural Medical College
India

Biochim Biophys Acta Proteins Proteom 2019 Jun 4;1867(6):604-615. Epub 2019 Apr 4.

Department of Protein Chemistry and Technology, CSIR-Central Food Technological Research Institute, Mysuru, 570020, India; Academy of Scientific and Innovative Research, New Delhi, India. Electronic address:

In mammalian cells, human 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), a rate-limiting endoplasmic reticulum (ER) bonded enzyme, plays a central role in the cholesterol homeostasis via the negative feedback mechanism. The present study indicates that the interactions of novel peptides with the catalytic domain of HMGCR, provides an alternative therapeutic candidate for reducing cholesterol. The potential natural origin of HMGCR peptide inhibitors were filtered from the peptide library using the molecular docking, which revealed three strong candidates for inhibition. This information was used for synthesizing peptides, which were evaluated for inhibition against HMGCR. The stronger docking interactions were confirmed by experimental dissociation constant (K) values of 9.1 × 10 M, 1.4 × 10 M and 1.2 × 10 M for peptides NALEPDNRIESEGG (Pep-1), NALEPDNRIES (Pep-2) and PFVKSEPIPETNNE (Pep-3) respectively. The immunological based interactions show a strong evidence of peptide-HMGCR complexes. The LDL uptake showed enhancements after treatments with peptides in the extracellular environment of HepG2 cells, which was further, corroborated through increase in the immunofluorescence signal of the localized LDL-R protein expression on the cell membrane. The results showed that the mRNA and protein expression of transcription factors were significantly up-regulated showing regulation of cholesterol biosynthesis in peptide treated HepG2 cells. The binding of transcription factors, sterol regulatory element (SRE) and cAMP-response element (CRE) on HMGCR promotor further confirms the cholesterol biosynthesis regulation. All the above results suggested a key role of peptide/s in alleviating cholesterol accumulation in tissue via inhibition of rate-limiting HMGCR enzyme.

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http://dx.doi.org/10.1016/j.bbapap.2019.04.002DOI Listing
June 2019
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