Precision in situ cryogenic correlative light and electron microscopy of optogenetically positioned organelles.

Unambiguous targeting of cellular structures for in situ cryo-electron microscopy in the heterogeneous, dense and compacted environment of the cytoplasm remains challenging. Here, we have developed a cryogenic correlative light and electron microscopy (cryo-CLEM) workflow that utilizes thin cells grown on a mechanically defined substratum for rapid analysis of organelles and macromolecular complexes by cryo-electron tomography (cryo-ET). We coupled these advancements with optogenetics to redistribute perinuclear-localised organelles to the cell periphery, allowing visualisation of organelles that would otherwise be positioned in cellular regions too thick for cryo-ET.

The desmosome-intermediate filament system facilitates mechanotransduction at adherens junctions for epithelial homeostasis.

Epithelial homeostasis can be critically influenced by how cells respond to mechanical forces, both local changes in force balance between cells and altered tissue-level forces. Coupling of specialized cell-cell adhesions to their cytoskeletons provides epithelia with diverse strategies to respond to mechanical stresses. Desmosomes confer tissue resilience when their associated intermediate filaments (IFs) stiffen in response to strain, while mechanotransduction associated with the E-cadherin apparatus at adherens junctions (AJs) actively modulates actomyosin by RhoA signaling.

Single molecule visualization of tropomyosin isoform organization in the mammalian actin cytoskeleton.

The actin cytoskeleton is composed of both branched and unbranched actin filaments. In mammals, the unbranched actin filaments are primarily copolymers of actin and tropomyosin. Biochemical and imaging studies indicate that different tropomyosin isoforms are segregated to different actin filament populations in cells and tissues, providing isoform-specific functionality to the actin filament.

The Biology of Lipids.

Lipids are the defining features of cellular membranes. They act collectively to form a variety of different structures, and understanding their complex behavior represents an early example of systems biology. A multidisciplinary approach is needed to analyse the functions of lipids in biological systems, and new work is providing fascinating insights into their roles in membrane biology, metabolism, signaling, subcellular dynamics and various disease processes.