Lipid Cross-Linking


Cross-linking locally stabilizes meta-stable states that are vital for signal transduction.  My group has also investigated the effects of cross-linking lipids, mimicking the B cell interaction between the membrane-bound B cell receptor (BCR) and foreign antigens.  We model this specific interaction using two-phase vesicles to represent slow (Lo; liquid-ordered) and fast diffusion (Ld; liquid-disordered) regions on a cell membrane.  The cross-linking occurs within the Ld region or domain, and we have found a marked increase in multidomain vesicles, suggesting that the energetic cost of the boundary has decreased.  These multidomain vesicles are quite long lasting, implying that cross-linking in a biological system, such as the BCR example, stabilizes a local region.  Our model of this common membrane response to a simple cross-linking event demonstrates the ease of inducing lateral heterogenities and nonideal mixing within a lipid bilayer.  We expect to further elucidate these findings by investigating the effects of cross-linking at the cusp of a two-phase boundary region and the lipid diffusion perturbations in forthcoming papers.

An example of a cross-linked two-phase (Ld/Lo, Ld labeled) vesicle with multiple domains.  The movie scrolls through the three dimensional vesicle.

An example of a polka-dotted two-phase (Ld/Lo, Ld labeled) vesicle.  The image is a three-dimensional rendering of a z-stack.  See ref [1].

[1] M.S. Kessler, R.L. Samuel, S.D. Gillmor, Polka-Dotted Vesicles: Lipid Bilayer Dynamics and Cross-Linking Effects, Langmuir, 29 (2013) 2982-2991. (abstract)

[2] R.L. Samuel, M.S. Kessler, S.D. Gillmor, in prep, (2015).