Roles of Cross-Membrane Transport and Signaling in the Maintenance of Cellular Homeostasis

Abstract

Organelles allow specialized functions within cells to be localized, contained and independently regulated. This separation is oftentimes achieved by selectively permeable membranes, which enable control of molecular transport, signaling between compartments and containment of stress-inducing factors. Here we consider the role of a number of membrane systems within the cell: the plasma membrane, that of the endoplasmic reticulum, and then focusing on the nucleus, depository for chromatin and regulatory centre of the cell. Nuclear pores allow shuttling of ions, metabolites, proteins and mRNA to and from the nucleus. The activity of transcription factors and signaling molecules is also modulated by translocation across the nuclear envelope. Many of these processes require ‘active transportation’ against a concentration gradient and may be regulated by the nuclear pores, Ran-GTP activity and the nuclear lamina. Cells must respond to a combination of biochemical and physical inputs and we discuss too how mechanical signals are carried from outside the cell into the nucleus through integrins, the cytoskeleton and the ‘linker of nucleo- and cyto-skeletal’ (LINC) complex which spans the nuclear envelope. Regulation and response to signals and stresses, both internal and external, allow cells to maintain homeostasis within functional tissue.

An immortalised mesenchymal stem cell line maintains mechano-responsive behaviour and can be used as a reporter of substrate stiffness

“…Translocation of TFs between cytoplasm and nucleoplasm is a common motif within mechanosensing pathways, allowing TF activity to be modulated and thus providing control over specific transcriptionally regulated programs, such as lineage selection 41 , 42 . Regulation of the subcellular localization of TFs YAP1 and MKL1 as a function of substrate stiffness was found to be maintained in the immortalised MSCs (Fig.…”

Candida albicans—The Virulence Factors and Clinical Manifestations of Infection

“…It is synthesized on the endoplasmic reticulum and lipid bodies [ 14 ]. In the cell membrane, there is a phospholipid bilayer containing proteins with the role of receptors, but also some whose role is transport and also signal transduction [ 15 ].…”

Biophysical characterization of lutein or beta carotene-loaded cationic liposomes

“…On the other hand, they selectively allow the permeation of ions and other small molecules to facilitate cellular signaling and promote cell homeostasis. [1][2][3] Furthermore, they have the ability to selectivity degrade toxins (such as free radicals) that pass into the cell, which can result in damage to DNA and other cellular components. Carotenoids (plant natural pigments) have been found to support membrane defense through direct quenching and modulation of its physical properties.…”