Scientific work presentation:Speaker: Huang Hua (from Soong Tuck Wah’s group)
1st short talk title: Evolutionary conservation and physiological roles of A-to-I RNA editing in CaV1.3 channels
Abstract:
We have reported that voltage gated calcium channel CaV1.3 undergoes ADAR2 mediated A-to-I RNA editing in a developmental and tissue selective fashion. Our recent paper demonstrated such editing is dictated by an intronic editing complementary sequence (ECS) that forms RNA duplex structure with the edited exon 41. Intriguingly, in silico alignment in the encode database demonstrated high conservation of ECS and exonic sequence across vertebrates. Correlatingly, editing of CaV1.3 mRNA was observed in most of experimental animal models such as rodents, pig, zebra fishes and macaque. Further tissues profiling of zebra fishes reports lack of editing in peripheral tissues such as muscle and testis, a trend similarly observed in rodents and human. Behaviour study showed mice lack of editing of Cav1.3 displayed longer retention of fear memory. We have similarly deleted the ECS sequence in zebra fish. Experiments are underway to understand the physiological roles of such molecular event in evolution.

2nd short talk title: Identification of tandem pore domain potassium channel KCNK5 as a novel target in Ph+ CML
Abstract:
Potassium channels are pore-forming transmembrane proteins that regulate a variety of cellular processes via controlling the potassium flow across biological membrane. Accumulating data implicates the dysregulation of potassium channel expression in different types of cancer. In the present study, quantitative real-time PCR reported overexpression of KCNK5 mRNA in K562 cells and Ph+ CML bone marrow samples as compared to normal bone marrow. Moreover, the expression of the KCNK5 mRNA and protein in K562 cells are sensitive to imatinib that blocks BCR-ABL tyrosine-kinase activity. In silico analysis of the Chip-seq database revealed strong interaction of c-MYC and Max binding to the promoter region of KCNK5, suggesting that BCR-ABL induced ectopic expression of the channel via Jak2 and c-MYC pathway. Sub-cellular fractionation experiment detects enrichment of KCNK5 channels in the lysosomal fraction, suggesting the potential function of the channels in regulating cellular metabolism. KCNK5 specific blocker clofilium inhibits channel function and proliferation of K562 cells. CRISPR/Cas9 mediated gene knockout (KO) in K562 cells suppresses tumor formation in mouse xenograft model. By tail vein injection, mice engrafted with KO cells survived significantly longer than mice transplanted with control cells. Taken together the study reports identification of KCNK5 potentially as a novel target in Ph+ CML.