A TRUNCATED FORM OF THE SOYBEAN 7S GLOBULIN ALFA PRIME SUBUNIT UP‐REGULATES LDL RECEPTORS IN HEP G2 CELLS

Abstract

7S soy globulin and its alfa prime subunit have been shown to positively modulate the LDL receptor activity both in vitro and in vivo. The aim of the study was to evaluate the effect of a truncated form of alfa prime subunit (t alfa prime), obtained by a biotechnological approach, on cell cholesterol homeostasis. Hep G2 cells were incubated in the presence/absence of the whole alfa prime subunit (3.5×10−6M) or the t alfa prime at concentration of 10−5 M and 10−6M. A dose‐dependent increase (P<0.05) in the up‐regulation of the LDL receptor was detected in cells exposed to t alfa prime versus that found in controls. Moreover, the LDL uptake (+ 185%) and degradation (+ 156%) of cells tested to the higher dose of t alfa prime (8×10−6M) was similar to that found in cells incubated with 1 M simvastatin. These results were confirmed by a dose‐dependent increase in the SREBP2, PCSK9 and LDL‐R mRNAs. Hep G2 cells exposed to t alfa prime for 24 h showed an increased uptake of fluorescent LDL versus both whole alfa prime and controls, as detected by fluorescente microscopy: the fuorescence intensity was proportional to the amount of LDL uptaked by the cells as confirmed by FACS analysis. These findings open new prospects in the studies aimed at identifying the regulatory peptide/s from soybean proteins and the mechanism/s involved in this biological response, in view of their potential utilization as nutraceutics.