Loss of PIKfyve drives the spongiform degeneration in prion diseases.

Brain-matter vacuolation is a defining trait of all prion diseases, yet its cause is unknown. Here, we report that prion infection and prion-mimetic antibodies deplete the phosphoinositide kinase PIKfyve-which controls endolysosomal maturation-from mouse brains, cultured cells, organotypic brain slices, and brains of Creutzfeldt-Jakob disease victims. We found that PIKfyve is acylated by the acyltransferases zDHHC9 and zDHHC21, whose juxtavesicular topology is disturbed by prion infection, resulting in PIKfyve deacylation and rapid degradation, as well as endolysosomal hypertrophy and activation of TFEB-dependent lysosomal enzymes.

The rod signaling pathway in marsupial retinae.

The retinal rod pathway, featuring dedicated rod bipolar cells (RBCs) and AII amacrine cells, has been intensely studied in placental mammals. Here, we analyzed the rod pathway in a nocturnal marsupial, the South American opossum Monodelphis domestica to elucidate whether marsupials have a similar rod pathway. The retina was dominated by rods with densities of 338,000-413,000/mm².