The inner-nuclear-envelope protein emerin regulates HIV-1 infectivity

Primate lentiviruses such as human immunodeficiency type 1 (HIV-1) have the capacity to infect non-dividing cells such as tissue macrophages. In the process, viral complementary DNA traverses the nuclear envelope to integrate within chromatin. Given the intimate association between chromatin and the nuclear envelope, we examined whether HIV-1 appropriates nuclear envelope components during infection. Here we show that emerin, an integral inner-nuclear-envelope protein, is necessary for HIV-1 infection. Infection of primary macrophages lacking emerin was abortive in that viral cDNA localized to the nucleus but integration into chromatin was inefficient, and conversion of viral cDNA to non-functional episomal cDNA increased. HIV-1 cDNA associated with emerin in vivo, and the interaction of viral cDNA with chromatin was dependent on emerin. Barrier-to-autointegration factor (BAF), the LEM (LAP, emerin, MAN) binding partner of emerin, was required for the association of viral cDNA with emerin and for the ability of emerin to support virus infection. Therefore emerin, which bridges the interface between the inner nuclear envelope and chromatin, may be necessary for chromatin engagement by viral cDNA before integration.     

HIV-1 Nef intersects the macrophage CD40L signalling pathway to promote resting-cell infection

All primate lentiviruses (HIV-1, HIV-2, SIV) encode Nef proteins, which are important for viral replication and pathogenicity in vivo. It is not known how Nef regulates these processes. It has been suggested that Nef protects infected cells from apoptosis and recognition by cytotoxic T lymphocytes. Other studies suggest that Nef influences the activation state of the infected cell, thereby enhancing the ability of that cell to support viral replication. Here we show that macrophages that express Nef or are stimulated through the CD40 receptor release a paracrine factor that renders T lymphocytes permissive to HIV-1 infection. This activity requires the upregulation of B-cell receptors involved in the alternative pathway of T-lymphocyte stimulation. T lymphocytes stimulated through this pathway become susceptible to viral infection without progressing through the cell cycle. We identify two proteins, soluble CD23 and soluble ICAM, that are induced from macrophages by Nef and CD40L, and which mediate their effects on lymphocyte permissivity. Our results reveal a mechanism by which Nef expands the cellular reservoir of HIV-1 by permitting the infection of resting T lymphocytes.     

Topography of soluble gliofibrillar protein (GFA) in aged human brain]

A great variation was observed in the amount of soluble GFA depending on the brain area. Large amounts were found in the chiasma and in the pons whereas the cortical grey matter was poor. It is suggested that soluble GFA represents a potentiality of defense of the nervous tissue.