February 8, 2024
Katherine McJunkin to present Division of Biology Seminar
Submitted by Division of Biology
Katherine McJunkin, Stadtman tenure-track investigator at the National Institute of Diabetes and Digestive and Kidney Diseases, will present "The Hunter Becomes the Hunted: Mechanisms of MicroRNA Decay" as part of the Division of Biology Seminar Series at 3:30 p.m. Monday, Feb. 12, in 221 Ackert Hall.
MicroRNAs are crucial regulators of gene expression in all aspects of development and physiology. Though they are tiny — 22-23nt long — even within that length a tinier sub-set of bases, the 7-nt "seed" sequence at positions 2-8, contains most of the functional information for target recognition. Because of the importance of the seed, identifying real biochemical and biologically important microRNA-target relationships is exceedingly difficult.
McJunkin will share recent work on using functional genomics via CRISPR-based screens to identify phenotype-relevant microRNA-target pairs. Because they are so tiny, another important and elusive question is how microRNAs are targeted for degradation in a sequence-specific way.
We have recently identified a decay mechanism that targets a group of embryonically-expressed microRNAs — the mir-35 family — for degradation based on their seed sequence. This mechanism is related to target-directed microRNA degradation, or TDMD, a process in which extensive seed and non-seed interactions between a microRNA and a specialized TDMD-triggering RNA induce proteasomal decay of the microRNA's protective protein partner, Argonaute — and subsequent decay of the unprotected microRNA. The extent of the non-seed base pairing in TDMD was previously thought to induce a conformational change in the Argonaute-microRNA complex, driving downstream ubiquitination and decay. The lack of these non-seed interactions in the TDMD of mir-35 opens up the possibility that other unknown factors are actually responsible for driving decay downstream of microRNA interaction with functionally specialized TDMD-triggering RNAs.
If you would like to visit with McJunkin, please contact Anna Zinovyeva at zinovyeva@k-state.edu.