Cytoplasmic and nuclear targeted delivery of peptides

Michelle L Brickner, Purdue University

Abstract

This research addressed the difficulties in targeting delivery of hydrophilic peptide agents to living cells. The delivery of large hydrophilic molecules has long been an obstacle in the targeted delivery of therapeutic agents. In this work, several delivery technologies have been examined. One means of delivering peptides addressed was the encapsulation of amphiphilic peptides into folate-targeted liposomes. This liposome delivery technology has the added challenge that following endocytosis, delivered agents are often trapped within endosomal compartments. The designed EALA3 peptide demonstrated a drastic conformational change, which when triggered by the acidic pH of the endosome, allowed for the cargo unloading of the liposomal contents. A lipid-based technology commonly used for the delivery of DNA in gene therapy applications was addressed as a means of delivering peptide inhibitors of the transcription factor Jun. A cationic lipofect reagent was successfully used to deliver Fos-derived interfacial peptide inhibitors that interacted with Jun's leucine zipper region and disrupted its dimerization ability. This prevented Jun from binding to DNA and activating transcription in an in vitro assay. A short peptide sequence derived from the transcription factor NF-κB was found to enter tumor cells in vitro through their polyamine uptake system. This peptide consists of NF-κB's nuclear localization sequence, therefore, upon entry into MCF7 breast cancer cells, this peptide was also shown to locate to the nucleus. This peptide might prove to be a means of delivering and shuttling covalently attached molecules to the nucleus of live cells. Initial attempts to exploit this mechanism of entry into cancer cells were made by conjugating a known cytotoxic drug, methotrexate, onto this peptide.

Degree

Ph.D.

Advisors

Chmielewski, Purdue University.

Subject Area

Biochemistry

COinS