mechanisms of age-dependent olfactory loss

Age-related olfactory sensory decay, including smell loss and defective odor-discrimination, during normal and pathological aging is a prominent phenomenon in older organisms. Age-related olfactory impairments are a comprehensive consequence of the dysfunction of various components of the olfactory system that occur in both olfactory sensory neurons (OSNs) and interneurons in C. elegans. Using specific genetic manipulation, patch-clamp recording, fluorescence imaging and chemotaxis assays, we aim to characterize the physiological properties of sensory neurons and interneurons with age. The project will then assess alternations in intracellular signaling cascades and different ONSs’ neurotransmitter release. Since OSNs’ glutamate and neuropeptide release is controlled by different exocytosis mechanisms, it is possible that there is a unique decay rate for each neurotransmitter release. Finally, we will perform temporal RNAi to assess age-related abnormality in the neuropeptide feedback loop of the C. elegans olfactory system. Our lab will combine single cell genetic assay with traditional functional assessment to address the fundamental question: how do olfactory neurons change during the aging process? Recently, next-generation transcript sequencing (RNA-seq) has been employed to evaluate transcriptome profiles with single cell resolution, which offers a powerful tool to understand functional alteration in aging neurons at the genetic level. Since each individual neuron in C. elegans has a specialized function and specific molecular signatures changing with age, combining physiological function analysis with genetic fingerprinting may hold the key to the fundamental questions of aging. However, how to link transcriptome profiles with physiological function in a signal cell is still a demanding technical challenge. To resolve the problem, we are developing a novel “Single Cell Patch-Clamp RNA-seq” (SCPR-seq) technique, which allows us to simultaneously carry out in vivo functional analyses and whole transcriptome analyses in a single olfactory cell at any specific developmental phase and with distinctive genetic backgrounds. In brief, a single target olfactory neuron in a dissected worm is physiologically characterized with patch-clamp recording. It is then isolated and collected for RNA sequence analysis with recording pipettes. The molecular heterogeneity analysis together with functional testing of neurons in young and aged worms will provide clear answers to the questions behind olfactory aging and identify unknown critical genes that regulate the aging process.