Search

AMP-activated protein kinase (AMPK) is a cellular energy sensor regulating metabolic homeostasis. In this study, we investigated the role of AMPK in response to human herpesvirus 6A (HHV-6A) infection. We show that HHV-6A infection significantly downregulates the active phosphorylated state of AMPK in infected T cells. Pharmacological activation of AMPK highly attenuated HHV-6A propagation. Mechanistically, we found that the activation of AMPK by AICAR blocked HHV-6-induced glycolysis by inhibiting glucose metabolism and lactate secretion, as well as decreasing expressions of key glucose transporters and glycolytic enzymes. In addition, mTOR signaling has been inactivated in HHV-6A infected T cells by AICAR treatment. We also showed that HHV-6A infection of human umbilical cord blood mononuclear cells (CBMCs) reduced AMPK activity whereas the activation of AMPK by metformin drastically reduced HHV-6A DNA replication and virions production. Taken together, this study demonstrates that AMPK is a promising antiviral therapeutic target against HHV-6A infection. • HHV-6A infection inhibits AMPK activity in infected T cells. • Pharmacological activation of AMPK reduces HHV-6A replication. • Activation of AMPK by AICAR blocks HHV-6-induced glycolysis and mTOR signaling. • AMPK is a promising antiviral therapeutic target against HHV-6A infection. [ABSTRACT FROM AUTHOR]

Human calcium sensing receptor (CaSR) senses calcium ion concentrations in vivo and is an important class of drug targets. Mutations in the receptor can lead to disorders of calcium homeostasis, including hypercalcemia and hypocalcemia. Here, 127 CaSR-targeted nanobodies were generated from camels, and four nanobodies with inhibitory function were further identified. Among these nanobodies, NB32 can effectively inhibit the mobilization of intracellular calcium ions (Ca2+ i) and suppress the G 12/13 and ERK 1/2 signaling pathways downstream of CaSR. Moreover, it enhanced the inhibitory effect of the calcilytics as a negative allosteric modulator (NAM). We determined the structure of complex and found NB32 bound to LB2 (Ligand-binding 2) domain of CaSR to prevent the interaction of LB2 domains of two protomers to stabilize the inactive state of CaSR. • 127 CaSR-targeting nanobodies were screened from camels. • NB32 effectively inhibit the mobilization of intracellular calcium ions. • NB32 enhanced the inhibitory effect of the calcilytics as a negative allosteric modulator (NAM). • Cryo-EM revealed that NB32 binds to the LB2 domain of CaSR. [ABSTRACT FROM AUTHOR]