BDNF and HIV-1 infection: Tat uptake into neurons induces miR-132 expression through CREB phosphorylation, down-regulates MecP2 and BDNF expression in neurons, and impairs neurite outgrowth and neuron survival; alternatively, Tat expression in astrocytes resulting from HIV-1 infection or Tat uptake into astrocytes induces miR-132 expression through CREB phosphorylation and down-regulates BDNF expression.