Perforin Promotes Amyloid Beta Internalisation in Neurons

Abstract

Studies on the mechanisms of neuronal amyloid-β (Aβ) internalisation are crucial for understanding the neuropathological progression of Alzheimer's disease (AD). We here investigated how extracellular Aβ peptides are internalised and focused on three different pathways: (i) via endocytic mechanisms, (ii) via the receptor for advanced glycation end products (RAGE) and (iii) via the pore-forming protein perforin. Both Aβ and Aβ were internalised in retinoic acid differentiated neuroblastoma (RA-SH-SY5Y) cells. A higher concentration was required for Aβ (250 nM) compared with Aβ (100 nM). The internalised Aβ showed a dot-like pattern of distribution whereas Aβ accumulated in larger and distinct formations. By confocal microscopy, we showed that Aβ and Aβ co-localised with mitochondria, endoplasmic reticulum (ER) and lysosomes. Aβ treatment of human primary cortical neurons (hPCN) confirmed our findings in RA-SH-SY5Y cells, but hPCN were less sensitive to Aβ; therefore, a 20 (Aβ) and 50 (Aβ) times higher concentration was needed for inducing uptake. The blocking of endocytosis completely inhibited the internalisation of Aβ peptides in RA-SH-SY5Y cells and hPCN, indicating that this is a major pathway by which Aβ enters the cells. In addition, the internalisation of Aβ, but not Aβ, was reduced by 55 % by blocking RAGE. Finally, for the first time we showed that pore formation in cell membranes by perforin led to Aβ internalisation in hPCN. Understanding how Aβ is internalised sheds light on the pathological role of Aβ and provides further ideas of inhibitory strategies for preventing Aβ internalisation and the spreading of neurodegeneration in AD.

Evidence that Brain-Reactive Autoantibodies Contribute to Chronic Neuronal Internalization of Exogenous Amyloid-β1-42 and Key Cell Surface Proteins During Alzheimer’s Disease Pathogenesis

“…It also binds to many other proteins (albeit with lower affinities) found elsewhere in the blood and brain. Under conditions of BBB leak, the influx of vascular A␤ 42 into the brain leads to the formation of A␤ 42 -␣7nAChR complexes on neuronal cell surfaces, which are subsequently internalized, presumably via endocytosis, and accumulate readily within the lysosomal compartment of these cells [35,36]. Mechanisms driving internalization of A␤ 42 and intraneuronal accumulation remain poorly understood.…”

Glycosyl chains and 25‐hydroxycholesterol contribute to the intracellular transport of amyloid beta (Aβ‐42) in Jurkat T cells

“…Lana et al . demonstrated that Aβ‐42 colocalizes with ER, lysosome, and mitochondria of differentiated SH‐SY5Y cells. Since in the depolymerized state of microtubules, Aβ‐42 resided only at the surface of membrane, thus depolymerization of microtubules possibly disturbs the endocytic transport of the peptides.…”

“…Thus, microtubules carry Ab peptides from the vicinity of plasma membrane to its destination which can be ER, mitochondria, Golgi bodies, or other cell organelle. Lana et al [4] demonstrated that Ab-42 colocalizes with ER, lysosome, and mitochondria of differentiated SH-SY5Y cells. Since in the depolymerized state of microtubules, Ab-42 resided only at the surface of membrane, thus depolymerization of microtubules possibly disturbs the endocytic transport of the peptides.…”

“…Recent studies have suggested different mechanisms for the internalization of Aβ, such as endocytic mechanisms, the pore‐forming protein perforin, and receptor‐mediated pathways . Endocytic transport or endocytosis is a membrane phenomenon and the basic structure of the membrane is a lipid bilayer, which is largely composed of cholesterol, sphingolipids, and glycerophospholipids .…”

Shared cerebral metabolic pathology in non-transgenic animal models of Alzheimer's and Parkinson's disease

“…Unlike STZ, exogenous (similar to endogenous) Aβ peptide fragments seem to lack selectivity towards membrane molecular targets since the intracellular intake of Aβ peptides is not operated via a selective transporter. Instead, three different pathways of its internalization have been proposed; for both Aβ 1-40 and Aβ 1-42 endocytic mechanisms seem to be the major ones although both could enter a neuron via the pore-forming protein perforin, while only Aβ 1-42 was shown to enter via the receptor for advanced glycation end products (RAGE) (Lana et al 2017). Endocytosis is two times more efficient for soluble Aβ 1-42 than for soluble Aβ 1-40 but both are predominantly taken up via clathrin-and dynaminindependent mechanisms (Wesen et al 2017).…”