Liu, S.-S. | Search bioRxiv

bioRxiv2021

Presynaptic HCN channels constrain GABAergic synaptic transmission in pyramidal cells of the medial prefrontal cortex

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are widely expressed in neurons in the central nervous system. It has been documented that HCN channels regulate the intrinsic excitability of pyramidal cells in the medial prefrontal cortex (mPFC) of rats. Here, we report that HCN channels limited GABAergic transmission onto pyramidal cells in the mPFC. Pharmacological block of HCN channels resulted in a significant increase in the frequency of both spontaneous and miniature inhibitory postsynaptic currents (IPSCs) in mPFC pyramidal cells. Such facilitation effect on mIPSCs required presynaptic Ca2+ influx and reversed by high-dose cAMP. Such facilitation did not exist in the presence of the T-type Ca2+ channel selective blockers. Immunofluorescence staining revealed that HCN channels expressed in presynaptic GABAergic terminals, as well as in both soma and neurite of parvalbumin-expressing (PV-expressing) basket cells in the mPFC. The present results indicate that HCN channels in GABAergic interneurons, most likely PV-expressing basket cells, constrain inhibitory control over layer 5-6 pyramidal cells through restricting presynaptic Ca2+ entry.

neuroscience↗

bioRxiv2020

Gut expressed vitellogenin is hijacked by a virus to facilitate its spread

Insect vitellogenin (Vg) has been considered to be synthesized in the female fat body, secreted into hemolymph, and taken up by developing oocytes to serve as nutrition for embryo development. However, the expression and function of Vg in other tissues are largely unknown. Here, we show that Vg is expressed in the whitefly midgut epithelial cells and secreted into gut lumen where it binds to the microvillar membrane. Furthermore, we find that the midgut expressed Vg is hijacked by Tomato yellow leaf curl virus to facilitate the movement of virus crossing the midgut wall. Silencing of Vg or immune-blocking the interaction between viral coat protein and midgut Vg inhibited virus movement across the midgut wall and decreased virus transmission. Our findings show possession of functional Vg in the midgut of an insect, and reveal a novel mechanism involved in the movement of virus crossing the midgut barrier of vector insect.

microbiology↗