Seminars & Symposia
Regulation of Lipid Homeostasis at Inter-Organelle Membrane Contact Sites by Nir Proteins
2022-12-27 11:00 ~ 2022-12-27 12:00
Venue: IBC R209
Speaker: Dr. Jen Liou
Current Position: Associate Professor, Sowell Family Scholar in Medical Research, Department of Physiology, UT Southwestern Medical Center, USA
Speaker Website: https://profiles.utsouthwestern.edu/profile/111270/jen-liou.html
Host: Dr. Ruey-Hwa Chen
Abstract:
Phosphatidylinositol 4,5-bisphosphate (PIP2) in the plasma membrane is a critical lipid molecule that regulates nearly all functional processes occurring at the cell surface. Additionally, PIP2 is hydrolyzed following receptor-induced activation of phospholipase C to generate second messengers for signal transduction. It is crucial to quickly replenish PIP2 in the plasma membrane following receptor-induced hydrolysis to sustain signaling outputs and to maintain PIP2-dependent cellular functions. Replenishment of plasma membrane PIP2 in receptor-stimulated cells involves transport of phosphatidylinositol (PI) from the endoplasmic reticulum (ER) to the plasma membrane for PIP2 re-synthesis. ER-plasma membrane contact sites are subcellular loci characterized by the close apposition of the ER to the plasma membrane. Recent findings revealed that the PI transfer proteins, Nir2 and Nir3, dynamically localize at ER-plasma membrane contacts to mediate replenishment of PIP2 hydrolyzed following receptor stimulation. Deficiency in Nir2 and Nir3 suppressed replenishment of PIP2 in the plasma membrane and Ca2+ signaling in receptor-stimulated cells. A third mammalian Nir protein, Nir1, has been linked to several human diseases including retinal dystrophy. Unlike Nir2 and Nir3, Nir1 lacks a PI transfer protein domain and readily localizes at ER-plasma membrane contacts in resting cells. The presence of Nir1 promotes Nir2 localization at ER-plasma membrane contacts to mediate PIP2 replenishment following receptor stimulation. Together, Nir proteins maintain plasma membrane PIP2 homeostasis at ER-plasma membrane contacts to support cell signaling and plasma membrane functions in receptor-stimulated cells.
Contact person: Ms. Nancy Liu
Tel: 27855696#2061
Email: liukchun@gate.sinica.edu.tw