GUCY1B3 Finally Accessible In Mandarin Chinese As Well As Romance Language!
To distinguish the effects of PrP(106�C126) on the two major chemical subclasses of DBB neurons, we performed GUCY1B3 single-cell RT-PCR analysis. Our data reveal that, of the chemical phenotypes in dissociated DBB cells, 50% of neurons are cholinergic and 29% are GABAergic, consistent with our previous results (Jhamandas et al., 2001). We were able to identify that both GABAergic and cholinergic neurons are affected by PrP(106�C126) and that both cell types were expressed with Kv4.2. Previous data had identified the gene encoding fast transient K+ channels (IA) in the rat somata and dendrite as Kv4.2 (Storm, 1990; Nerbonne et al., 2008). IA, which has been shown to play an important role in modulating neuronal excitability (Storm, 1990; Shen et al., 2008), is neuromodulated by acetylcholine (Nakajima et al., 1986) and GABA. Physiologically, IA produces this effect via increasing the rate of both action potential repolarization and accommodation (Viana et al., 1993; Zhang and McBain, 1995). Our studies indicated that PrP(106�C126) significantly reduces IA (22.0% decrease; P Pexidartinib duration in DBB neurons. In terms of cholinergic neurons, PrP(106�C126) may render cholinergic neurons hyperexcitable through loss of accommodation and prolonged depolarization, with a potential for eventual cell death from excessive Ca2+ influx. Studies have shown Kv4.2 expression in GABAergic interneurons as well as somata and dendrites of pyramidal cells (Burkhalter et al., 2006). Kv4.2 was expected to weaken inhibition of GABA during dendritic depolarization by back-propagating action potentials (Burkhalter et al., 2006). Hence, in our studies, a decrease potentiation of IA currents will result in a decreased inhibitory effect of GABA. As mentioned above, PrP(106�C126) has been shown to inhibit L-type VSCC in the rat cultured cerebellar granule cells (Thellung et al., 2000). Thellung et al. postulate that PrP(106�C126) impairs calcium homeostasis through its effects on a subset of voltage-sensitive calcium channels and, in BKM120 mouse turn, affects cell survival. Our studies suggest that an increase in excitability of DBB neurons may occur via an alternate mechanism, namely, that the PrP CR peptide PrP(106�C126) can cause a depression of a suite of potassium channels (IA, IK, and IA), which results in overall excitation of neurons. Although, in our study, PrP(106�C126) did not directly influence Ca2+ currents, prolonged depolarization resulting from blockade of K+ currents (in this case IK and/or IC) could lead to increased total Ca2+ influx through voltage-activated calcium channels.
