Etienne Boulter

French Institute of Health and Medical Research | Inserm · Institute of Research on Cancer and Ageing of Nice

LEGO® is a brand of toys that have entertained generations of children. Beyond amusement, LEGO® bricks also constitute a building ecosystem of their own that creators from the general public, as well as scientists and engineers, can use to design and assemble devices for all purposes, including scientific research and biotechnology. We describe sev...

Mechanical signals are essential for the regulation of many biological processes. Therefore, it has become paramount to account for these mechanical parameters when exploring biological processes. Here, we describe a protocol to apply cyclic uniaxial stretch on cells in culture using a LEGO®-based mechanical stretcher and a flexible custom-made pol...

Mechanical cues are essential for the regulation of cell and tissue physiology. Hence, it has become an utmost necessity for cell biologists to account for those mechanical parameters when investigating biological processes and they need devices to manipulate cells accordingly. Here, we report a simple mechanical cell-stretching system that can gen...

Mechanical and metabolic cues independently contribute to the regulation of cell and tissue homeostasis. However, how they cross-regulate each other during this process remains largely unknown. Here, we show that cellular metabolism can regulate integrin rigidity-sensing via the sphingolipid metabolic pathway controlled by the amino acid transporte...

Dysregulation of extracellular matrix (ECM) deposition and cellular metabolism promotes tumor aggressiveness by sustaining the activity of key growth, invasion, and survival pathways. Yet mechanisms by which biophysical properties of ECM relate to metabolic processes and tumor progression remain undefined. In both cancer cells and carcinoma-associa...

Skin homeostasis relies on fine tuning of epidermis/dermis interactions and is affected by aging. While extracellular matrix (ECM) proteins, such as integrins, are involved in aging, the molecular basis of the skin changes need to be further investigated. Here, we showed that integrin co-receptor, SLC3A2, required for cell proliferation, is express...

Mitochondria are more than just the powerhouse of cells; they dictate if a cell dies or survives. Mitochondria are dynamic organelles that constantly undergo fusion and fission in response to environmental conditions. We showed previously that mitochondria of cells in a low oxygen environment (hypoxia) hyperfuse to form enlarged or highly interconn...

CD98hc (SLC3A2) is the heavy chain component of the dimeric transmembrane glycoprotein CD98, which comprises the large neutral amino acid transporter LAT1 (SLC7A5) in cells. Overexpression of CD98hc occurs widely in cancer cells, and is associated with poor prognosis clinically, but its exact contributions to tumorigenesis are uncertain. In this st...

Skin aging is linked to reduced epidermal proliferation and general extracellular matrix atrophy. This involves factors such as the cell adhesion receptors integrins and amino acid transporters. CD98hc (SLC3A2), a heterodimeric amino acid transporter, modulates integrin signaling in vitro. We unravel CD98hc functions in vivo in skin. We report that...

Rho proteins are small GTPases of the Ras superfamily that regulate a wide variety of biological processes, ranging from gene expression to cell migration. Mechanistically, the major Rho GTPases function as molecular switches cycling between an inactive GDP-bound and an active GTP-bound conformation, although several Rho proteins spontaneously exch...

RhoGDI1 is one of the three major regulators of the Rho switch along with RhoGEFs and RhoGAPs. RhoGDI1 extracts prenylated Rho proteins from lipid membranes, sequesters them in the cytosol, and prevents nucleotide exchange or hydrolysis. In addition, RhoGDI1 protects prenylated Rho proteins from degradation. Here, we describe techniques to monitor...

The 'invisible hand' is a term originally coined by Adam Smith in The Theory of Moral Sentiments to describe the forces of self-interest, competition and supply and demand that regulate the resources in society. This metaphor continues to be used by economists to describe the self-regulating nature of a market economy. The same metaphor can be used...

Rho GTPases control many cellular processes, including cell survival, gene expression and migration. Rho proteins reside mainly in the cytosol and are targeted to the plasma membrane (PM) upon specific activation by guanine nucleotide exchange factors (GEFs). Accordingly, most GEFs are also cytosolic or associated with the PM. However, Net1, a RhoA...

Regulation of the Rho switch has been typically centered on their main regulators, RhoGEFs and RhoGAPs. On the side, RhoGDI proteins have been considered mostly as passive regulators devoid of catalytic activity simply holding Rho proteins in the cytosol. In the May issue of Nature Cell Biology,1 we describe a novel evolutionary conserved function...

At steady state, most Rho GTPases are bound in the cytosol to Rho guanine nucleotide dissociation inhibitors (RhoGDIs). RhoGDIs have generally been considered to hold Rho proteins passively in an inactive state within the cytoplasm. Here we describe an evolutionarily conserved mechanism by which RhoGDI1 controls the homeostasis of Rho proteins in e...

Focal adhesions have been intensely studied ever since their discovery in 1971. The last three decades have seen major advances in understanding the structure of focal adhesions and the functions they serve in cellular adhesion, migration, and other biological processes. In this chapter, we begin with a historical perspective of focal adhesions, pr...

During trans-endothelial migration (TEM), leukocytes use adhesion receptors such as intercellular adhesion molecule-1 (ICAM1) to adhere to the endothelium. In response to this interaction, the endothelium throws up dynamic membrane protrusions, forming a cup that partially surrounds the adherent leukocyte. Little is known about the signaling pathwa...

Extracellular matrix (ECM) receptors of the integrin family initiate changes in cell shape and motility by recruiting signaling components that coordinate these events. Integrin-linked kinase (ILK) is one such partner of beta1 integrins that participates in dynamic rearrangement of cell-matrix adhesions and cell spreading by mechanisms that are not...

Integrin-linked kinase (ILK) represents a key component of integrin signaling complexes that functions in concert with multiple binding partners to transmit cues from the extracellular matrix environment to the actin cytoskeleton. Both gain- and loss-of-function approaches to study ILK have confirmed the essential role of this protein in regulating...

Integrins play a key role in regulating endothelial cell survival, migration and differentiated function during angiogenic blood-vessel remodeling. Integrin-linked kinase (ILK) is a multidomain protein that interacts with the cytoplasmic tail of integrin beta subunits and is thought to participate in integrin-mediated signal transduction. We report...

Soluble mediators such as thrombin and sphingosine-1-phosphate regulate morphological changes in endothelial cells that affect vascular permeability and new blood vessel formation. Although these ligands activate a similar set of heterotrimeric G proteins, thrombin causes cell contraction and rounding whereas sphingosine-1-phosphate induces cell sp...