Death by glia

Abstract

No longer underestimated as only passive and supportive cells in the nervous system, glia have been shown to actively participate in synaptic transmission and information processing. Now, a collection of European researchers have highlighted some pathologic consequences of such signaling between astrocytes, microglia and neurons. Chemokines acting at CXCR4 receptors on astrocytes causes them to release tumor necrosis factor-α (TNFα); TNFα on these astrocytes triggers the formation of prostaglandins, which signals the astrocytes to release glutamate in a calcium-dependent manner. Reactive microglia potentiate this pathway and cause neuronal cell death by releasing two factors: (1) more TNFα, which akes astrocytes release higher — and potentially toxic – levels of glutamate and (2) the HIV coat protein gp120, which interacts with CXCR4 receptors on neurons to induce apoptosis. These complicated and deleterious cellular communications are published in the July issue of Nat. Neurosci.