Extended Data Fig. 1 |. A schematic summary of substance transport processes carried by proximal tubular epithelial cells (PTECs).

PTECs can secrete substances from the blood into the tubular lumen and the urine through transporter-mediated influx- and efflux-processes (green arrow line), reabsorb substances from the lumen back into the bloodstream through transcytosis or transporter-mediated efflux after lysosomal degradation (yellow arrow line). In addition, this newly discovered organelle extrusion of PTECs represents another route to remove the endocytosed and even biotransformed substances back into the tubular lumen for further renal clearance (red arrow line), along with elimination of other intracellular organelles. Since organelle extrusion also happens in healthy proximal tubules without AuNP injection, the physiological function is believed to self-renew intracellular contents and remove wastes to maintain homeostasis without cell division.