3.2 Overexpression of Lf in astrocytes promotes the Lf secretion into neurons
To uncover the mechanism of decreased Aβ burden in APP/PS1/Lf mice, we examined the expression levels of Lf in different gene-type mice. Immunoblotting showed that although the expressions of Lf in WT mouse brains and APP/PS1 mouse brains remain similar (Fig. 2A), the Lf content in APP/PS1/Lf mouse brains was significantly elevated compared to that in APP/PS1 mouse brains (Fig. 2B). Furthermore, the mouse primary astrocytes from Astro-Lf mice exhibited significant increases in Lf expression and Lf secretion compared to the primary astrocytes from WT mice (Fig. 2C), suggesting that overexpression of Lf in astrocytes promoted the Lf secretion from astrocytes. Similarly, the robust expression of human Lf was observed in the APP/PS1/Lf mouse brains (Fig. 2D), which was accompanied by strong immunostaining of human Lf in the NeuN-positive cells (Fig. 2E), suggesting that overexpression of Lf in astrocytes promoted the Lf secretion into neurons.