Protein-Labeling Fluorescent Probe for Folate Receptor α

Abstract

GPI-anchored folate receptor α (FRα) is an attractive anticancer drug target and diagnosis marker in fundamental biology and medical research due to its significant expression on many cancer cells. Currently, analyses of FRα expression levels are usually achieved using immunological methods. Due to the continual FRα synthesis and degradation, immunological methods are not suitable for studying real-time dynamic activities of FRα in living cells. In this paper, we introduce a rapid and specific FRα protein-labeling fluorescent probe, FR1, to facilitate the study of the dynamics of expression and degradation processes of endogenous FRα in living cells. With this labeling probe, insights on FRα protein lifetime and shedding from the cell surface can be obtained using fluorescence live-cell imaging and electrophoresis techniques. We revealed that FRα undergoes soluble domain release and endocytosis degradation simultaneously. Imaging results showed that most of the membrane FRα are transported to the lysosomes after 2 h of incubation. Furthermore, we also showed that the secretion of a FRα soluble domain into the environment is most likely accomplished by phospholipase. We believe that this protein-labeling approach can be an important tool for analyzing various dynamic processes involving FRα.

Expression of the Folate Receptor Proteins FOLR1 and FOLR2 in Correlation With Clinicopathological Variables of Gastric Cancer

“…Folates are required for single carbon transfer processes in eukaryotic cells, including the conversion of homocysteine to methionine and a variety of steps in de novo nucleotide synthesis [ 6 ]. Folate receptors (FRs) are cysteine-rich glycosylphosphatidylinositol (GPI)-anchored glycoprotein present on the cell surface, comprising three isoforms in humans that encode functional folate receptors namely FOLR1, FOLR2, and FOLR3 (also known as hFRα, hFRβ, and hFRγ, respectively) [ 7 ]. FRs are expressed in relatively low concentrations in normal cells but are mostly overexpressed on the cell surface of cancer cells, to compensate for folate requirements of rapidly proliferating cells.…”

Affinity-Switchable Interaction of Biotin and Streptavidin for the Signal-ON Detection of Small Molecules

“…To facilitate lateral flow detection, the biotin probes were conjugated to a carrier protein (SNAP-tag protein or rabbit IgG antibody) on the gold nanoparticles to generate Au@ASB-SFM and Au@ASB-TMP , respectively (Figure S1). − These two ASLFA gold nanoparticles were mixed with their respective binding protein (human carbonic anhydrase II for Au@ASB-SFM and dihydrofolate reductase for Au@ASB-TMP ) for the rapid and “Signal-ON” detection of various primary sulfonamides and trimethoprim drug.…”