Molecular tuning of sensory systems in octopus

All organisms sense and adapt to changes in their environment. Alterations in organismal state can lead to epigenetic changes that dramatically influence how an animal interacts with its environment. How organisms acutely alter sensation based on their behavioral state is not well understood. Octopuses are incredible sensory

specialists that use ‘taste by touch’ chemotactile sensation to interact with their environment. This sensory system is mediated by specialized chemotactile receptors (CRs) that detect poorly soluble molecules, such as those secreted by prey. If prey is unavailable for prolonged periods, do octopuses adapt to become more

sensitive predators? One mechanism octopus might deploy to adapt is epigenetic adenosine to inosine (A-to-I) editing. Octopuses readily diversify their proteomes through editing mRNA transcripts by swapping adenosine for inosine, which is interpreted as a guanosine during translation. This process allows a single gene to produce

multiple different translated proteins with potentially new functions. I will test the hypothesis that manipulation of organismal state biases preferential A-to-I editing to transiently alter protein sequence and function and modulate the detection of environmental signals most salient to the specific organismal state. Such a mechanism could

tune the unique octopus chemotactile sensory system to be more sensitive to prey molecules when hungry. This project will utilize a multifaceted approach spanning from RNA biology to animal behavior, providing me with ample opportunity to learn new concepts, techniques, and establish an independent trajectory following my

postdoctoral training. My diverse advisory team will provide expert guidance in cell physiology (Nicholas Bellono), RNA biology (Amy Lee), channel structure-function (Ryan Hibbs), and animal behavior (Venkatesh Murthy). In these studies, I will use molecular and biochemical approaches to identify which CRs are targets of RNA editing

or are preferentially translated in response to distinct organismal states, such as starved versus fed (Aim 1). Our preliminary data demonstrate that octopuses edit protein-coding regions of CRs during periods of starvation. After identifying the spectrum of CR variants, I will characterize the biophysical properties of recoded CRs against

unedited CRs to determine the functional consequences of state-dependent editing (Aim 2). I will focus my analysis on ligand sensitivity and ion permeation, which could account for increased sensitivity to prey molecules or altered neural signaling. Finally, I will leverage these discoveries to understand how the acute editing of

individual proteins affects adaptive organismal sensation (Aim 3). I will carry out behavioral assays to test whether specific changes in protein function correlate with altered behavior across starved and fed octopuses. For example, if starvation-induced RNA editing of CRs alters sensitivity to prey molecules to enhance prey

detection, I will test the threshold for chemically induced arm movement in behaving octopuses. Investigating how organisms can acutely regulate protein structure and function to alter behavior is novel and will provide fundamental insight into mechanisms of translation, signal transduction, and evolution.