PhotonSABER: new tool shedding light on endocytosis and learning mechanisms in vivo

Figures & data

Figure 1. PhotonSABER de-acidifies the luminal pH of endosomes upon light stimulation.

(a) PhotonSABER de-acidifies the luminal pH of endosomes upon light stimulation.The luminal pH is acidified by the coordinated activities of vacuolar-type H⁺-adenosine triphosphatase, chloride channels, and Na⁺/H⁺ exchangers (NHEs) in early to late endosomes in wild-type neurons. (b) The action of PhotonSABER in endosomes. The endosomal H⁺ is transported to the cytoplasm by light stimulation, and endosomal pH is elevated. Under this condition, endocytosis from the plasma membrane is severely impaired. (c) The function of NHEs is impaired in certain neurological disorders, leading to hyper-acidification of endosomes. (d) PhotonSABER is a useful tool for clarifying the pathogenesis of neurological disorders associated with defective NHEs. PhotonSABER is expected to rectify hyper-acidified endosomes and its associated phenotypes in neuronal cells derived from induced pluripotent stem cells from patients or from disease model mice.

Figure 2. Light stimulation inhibits epidermal growth factor (EGF) endocytosis in HeLa cells expressing PhotonSABER.

Light stimulation reduces colocalization of EGF and Rab7-green fluorescent protein (Rab7-GFP) in HeLa cells. HeLa cells expressing hemagglutinin-tagged PhotonSABER and Rab7-GFP were incubated with biotinylated EGF for 60 min. The regions marked by white squares are magnified in the bottom panels. Arrows indicate the colocalization of Rab7-GFP with EGF. The bar represents 10 μm.