Short-term transcriptomic response to plasma membrane injury

Multi-Omics of Familial Thoracic Aortic Aneurysm and Dissection: Calcium Transport Impairment Predisposes Aortas to Dissection

Several genetic defects, including a mutation in myosin heavy chain 11 (Myh11), are reported to cause familial thoracic aortic aneurysm and dissection (FTAAD). We recently showed that mice lacking K1256 of Myh11 developed aortic dissection when stimulated with angiotensin II, despite the absence of major pathological phenotypic abnormalities prior to stimulation. In this study, we used a comprehensive, data-driven, unbiased, multi-omics approach to find underlying changes in transcription and metabolism that predispose the aorta to dissection in mice harboring the Myh11 K1256del mutation. Pathway analysis of transcriptomes showed that genes involved in membrane transport were downregulated in homozygous mutant (Myh11ΔK/ΔK) aortas. Furthermore, expanding the analysis with metabolomics showed that two mechanisms that raise the cytosolic Ca2+ concentration-multiple calcium channel expression and ADP-ribose synthesis-were attenuated in Myh11ΔK/ΔK aortas. We suggest that the impairment of the Ca2+ influx attenuates aortic contraction and that suboptimal contraction predisposes the aorta to dissection.

Wrangling Actin Assemblies: Actin Ring Dynamics during Cell Wound Repair

To cope with continuous physiological and environmental stresses, cells of all sizes require an effective wound repair process to seal breaches to their cortex. Once a wound is recognized, the cell must rapidly plug the injury site, reorganize the cytoskeleton and the membrane to pull the wound closed, and finally remodel the cortex to return to homeostasis. Complementary studies using various model organisms have demonstrated the importance and complexity behind the formation and translocation of an actin ring at the wound periphery during the repair process. Proteins such as actin nucleators, actin bundling factors, actin-plasma membrane anchors, and disassembly factors are needed to regulate actin ring dynamics spatially and temporally. Notably, Rho family GTPases have been implicated throughout the repair process, whereas other proteins are required during specific phases. Interestingly, although different models share a similar set of recruited proteins, the way in which they use them to pull the wound closed can differ. Here, we describe what is currently known about the formation, translocation, and remodeling of the actin ring during the cell wound repair process in model organisms, as well as the overall impact of cell wound repair on daily events and its importance to our understanding of certain diseases and the development of therapeutic delivery modalities.

Cellular and molecular mechanisms underlying plasma membrane functionality and integrity

The plasma membrane not only protects the cell from the extracellular environment, acting as a selective barrier, but also regulates cellular events that originate at the cell surface, playing a key role in various biological processes that are essential for the preservation of cell homeostasis. Therefore, elucidation of the mechanisms involved in the maintenance of plasma membrane integrity and functionality is of utmost importance. Cells have developed mechanisms to ensure the quality of proteins that inhabit the cell surface, as well as strategies to cope with injuries inflicted to the plasma membrane. Defects in these mechanisms can lead to the development or onset of several diseases. Despite the importance of these processes, a comprehensive and holistic perspective of plasma membrane quality control is still lacking. To tackle this gap, in this Review, we provide a thorough overview of the mechanisms underlying the identification and targeting of membrane proteins that are to be removed from the cell surface, as well as the membrane repair mechanisms triggered in both physiological and pathological conditions. A better understanding of the mechanisms underlying protein quality control at the plasma membrane can reveal promising and unanticipated targets for the development of innovative therapeutic approaches.