response to fluid shear stress

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a fluid shear stress stimulus. Fluid shear stress is the force acting on an object in a system where the fluid is moving across a solid surface. [GOC:sl]

Fluid shear stress (FSS) is a mechanical force exerted by the flow of fluids, such as blood, on the surfaces of cells and tissues. It is a ubiquitous physical stimulus in biological systems, particularly in the cardiovascular system, where blood flow constantly exerts FSS on the inner lining of blood vessels, known as the endothelium. This mechanical force plays a crucial role in regulating a wide range of cellular and physiological processes, including vascular homeostasis, angiogenesis (formation of new blood vessels), and inflammation.

The response to FSS is a complex and multifaceted process that involves a cascade of signaling events within the cell, ultimately leading to changes in gene expression, protein synthesis, and cell behavior. The process begins with the detection of FSS by mechanosensitive proteins on the cell surface. These proteins, such as integrins, cadherins, and ion channels, directly sense the mechanical force and initiate downstream signaling pathways.

One of the key signaling pathways activated by FSS is the PI3K/Akt pathway. This pathway is involved in cell survival, growth, and metabolism. Upon FSS stimulation, the PI3K/Akt pathway is activated, leading to phosphorylation of Akt, a protein kinase involved in a variety of cellular processes. Activated Akt promotes cell survival and inhibits apoptosis (programmed cell death), thereby contributing to the maintenance of vascular integrity.

Another important pathway activated by FSS is the MAPK pathway. This pathway is involved in cell proliferation, differentiation, and inflammation. FSS activates MAPK kinases, such as ERK1/2, JNK, and p38, which in turn regulate the expression of genes involved in these processes. Activation of MAPK pathways can promote angiogenesis, a process that involves the formation of new blood vessels, which is essential for tissue repair and growth.

Furthermore, FSS can trigger the release of various signaling molecules, including nitric oxide (NO), prostaglandins, and growth factors, which contribute to the overall cellular response. NO, a potent vasodilator, is released by endothelial cells in response to FSS, leading to relaxation of blood vessels and improved blood flow. Prostaglandins, a class of lipids, are also released in response to FSS and contribute to the regulation of inflammation and blood vessel function.

The response to FSS is highly dynamic and depends on several factors, including the magnitude and duration of the force, the type of cells involved, and the presence of other signaling cues. For example, different levels of FSS can induce distinct responses in endothelial cells, with low levels promoting survival and growth, while high levels can trigger apoptosis.

In summary, response to fluid shear stress is a crucial biological process that plays a critical role in maintaining vascular health and regulating a wide range of cellular functions. It involves complex signaling pathways and the release of signaling molecules, ultimately leading to changes in gene expression, protein synthesis, and cell behavior. This dynamic process is essential for tissue development, repair, and homeostasis.'
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