Harbour Victoria, Casillas Candice, Siddiqui Zain, Sarkar Biplab, Sanyal Sreya, Nguyen Peter, Kim Ka Kyung, Roy Abhishek, Iglesias-Montoro Patricia, Patel Saloni, Podlaski Frank, Tolias Peter, Windsor William, Kumar Vivek
Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States.
ACS Appl Bio Mater. 2020 Dec 21;3(12):8978-8988. doi: 10.1021/acsabm.0c01229. Epub 2020 Dec 2.
High levels of serum low-density lipoprotein (LDL) cholesterol contribute to atherosclerosis, a key risk factor of cardiovascular diseases. PCSK9 is a circulatory enzyme that downregulates expression of hepatic LDL receptors, concomitantly increasing serum LDL-C. This work investigates a small, self-assembling peptide, EPep2-8, as a peptide inhibitor of PCSK9. EPep2-8 is a multidomain peptide comprising a self-assembling domain, E2, conjugated to a bioactive domain, Pep2-8, previously shown to inhibit PCSK9. The E2 domain facilitates self-assembly of EPep2-8 into long, nanofibrous polymers with an underlying supramolecular β-sheet secondary structure. Intermolecular interactions between nanofibers drive EPep2-8 to form a thixotropic and cytocompatible hydrogel in aqueous and charge-neutral solutions. These properties enable EPep2-8 to be delivered as an in situ depot for regulation of lipoprotein homeostasis. In surface plasmon resonance studies, EPep2-8 bound specifically to PCSK9 with an apparent, noncovalent, and irreversible dissociation, significantly improving the binding affinity of Pep2-8 alone ( = 667 ± 48 nM). Increased binding affinity of EPep2-8 is primarily due to the superstoichiometric interaction of the peptide with PCSK9. Promisingly, EPep2-8 retains bioactivity , engendering dose-dependent uptake of LDL-C in hepatocytes. This mechanism of self-assembly on a target site may be a simple method to improve the affinity of peptide inhibitors.
高水平的血清低密度脂蛋白（LDL）胆固醇会导致动脉粥样硬化，这是心血管疾病的一个关键危险因素。前蛋白转化酶枯草溶菌素9（PCSK9）是一种循环酶，可下调肝脏LDL受体的表达，从而使血清LDL-C水平升高。本研究考察了一种小型自组装肽EPep2-8作为PCSK9的肽类抑制剂的效果。EPep2-8是一种多结构域肽，由一个自组装结构域E2与一个生物活性结构域Pep2-8偶联而成，此前研究表明Pep2-8可抑制PCSK9。E2结构域有助于EPep2-8自组装成长的纳米纤维聚合物，其具有潜在的超分子β-折叠二级结构。纳米纤维之间的分子间相互作用促使EPep2-8在水性和电荷中性溶液中形成触变性且细胞相容性良好的水凝胶。这些特性使EPep2-8能够作为原位储存库用于调节脂蛋白稳态。在表面等离子体共振研究中，EPep2-8与PCSK9特异性结合，呈现出明显的、非共价且不可逆的解离，显著提高了单独Pep2-8的结合亲和力（ = 667 ± 48 nM）。EPep2-8结合亲和力的提高主要归因于该肽与PCSK9的超化学计量相互作用。令人鼓舞的是，EPep2-8保留了生物活性，在肝细胞中引起LDL-C的剂量依赖性摄取。这种在靶位点的自组装机制可能是提高肽类抑制剂亲和力的一种简单方法。
