Bio2000 Lectures

Handout for Lipids, Cell Membranes and Ion Homeostasis  (December 12 and 14 in Shanghai; December 15 and 16 in Beijing) Jianjie Ma, Ph.D. Department of Physiology and Biophysics Robert Wood Johnson Medical School Piscataway, NJ 08854 732-235-4494 (Phone), 732-235-4483 (Fax), [email protected] A.

Fundamental functions of biological membrane Barrier Catalyst Battery Signal relay

B.

Fluid mosaic model of membrane Lipid bilayer Asymmetry Membrane protein Motion and fluidity Why bilayers? Application in biotechnology: liposome-mediated gene transfection and drug delivery coating of medical devices lung surfactant

C.

Classes of membrane proteins Receptors Transporters Ion channels How to isolate and purify membrane proteins? detergent and critical micelle concentration (CMC) manipulations to avoid denaturation of purified protein

D.

Membrane potential Charge separation and voltage Capacitance: C = εoε A/d, εo = 8.85x10-12 CV-1m-1 Ion movements and resting membrane potential: Nernst equation

Remember: only small change in ion movement is sufficient to generate large electrical signal. E.

Membrane excitability Permeability Permeability change and action potential Patch clamp and single channel measurement

Why different types of ion channels? channelopathies and genetic diseases F.

Channelopathy of Cystic Fibrosis CFTR as a PKA and ATP-dependent Cl channel Different ways of mutation can affect channel function Structure-function studies of ion channels

G.

Specialized membrane structures Rafts and caveolae Subcellular organelles Mitochondria and endoplasmic reticulum Junctional membrane coupling

A.

An Example – membranes and proteins involved in regulation of [Ca]I T-tubule and sacroplasmic reticulum in muscle Forward signal transduction – surface excitation to intracellular Ca release Backward signal transduction – store Ca depletion to capacitative Ca entry Junctophilin, novel membrane protein with essential role in membrane coupling What can we learn from Ca sparks measurement? Question: the essence of keeping low intracellular [Ca]?

H.

Ca and cardiovascular diseases – therapeutics and drug discovery Membrane-membrane coupling and progression of heart hypertrophy to failure Targeting intracellular Ca release in sudden death with Ca antagonists Ameliorating the cardiotoxic effect of doxorubicin with natural products Targeting alpha-kinase in reperfusion-mediated injury of cardiac myocytes

I.

Ca and apoptosis Ca signaling in cytochrome c release and apoptosis Ca-inducible genes in resistance to apoptosis of cancer cells Synergistic movements of Ca and Bax in apoptosis of cancer cells

key to class participation: a) take very good notes b) participate in class discussion c) think together with the lecturer

reading materials: Alberts et at., “Cell Biology” Hille: “Ionic Channels of Excitable Membranes”

discussion paper: White et al. (2005) The endoplasmic reticulum gateway to apoptosis by Bcl-xL modulation of the InsP3R. Nat Cell Biol. 7: 1021-1028.