Sheddase

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Diagram of an ectodomain shedding ADAM metalloprotease. Ectodomain shedding en.svg
Diagram of an ectodomain shedding ADAM metalloprotease.

Sheddases are membrane-bound enzymes that cleave extracellular portions of transmembrane proteins, releasing the soluble ectodomains from the cell surface. Many sheddases are members of the ADAM or aspartic protease (BACE) protein families. [1]

Contents

These enzymes can activate a transmembrane protein if it is a receptor (e.g., HER2), or cut off the part of the transmembrane protein which has already bound an agonist (e.g., in the case of EGFR), allowing this agonist to go and stimulate a receptor on another cell. Hence, sheddases demultiply[ clarification needed ] the yield of agonists. Sheddase inhibitors active on ADAM10 and ADAM17 can potentiate anti-cancer therapy. [2]

Functions

It has been postulated that the activity of sheddases occurs in relation to the amount of general enzymatic activity. Research indicates that sheddases are instead related to phosphatidylserine exposure. When PSA-3 cells' ability to synthesize phosphatidylserine was repressed, sheddase activity decreased, and the sheddase activity returned to normal levels when the cells were again able to synthesize phosphatidylserine. This led researchers to conclude that phosphatidyserine exposure is necessary for cells to exhibit sheddase activity. [3]

Uses

Due to the nature of the mechanisms and functions of sheddase enzymes, they have been studied on the basis of discovering possible uses in medicine. One such use is in the treatment of allergic responses and other processes of the immune system. ADAM10 is responsible for the shedding of the CD23 Immunoglobulin receptor, which releases soluble sCD23. [4] sCD23 present in the blood serum contributes to immune response and, to some, the onset of inflammatory disease such as asthma. Given that ADAM10 sheddase cleaves CD23 and increases the levels of sCD23, possible treatments for these diseases may center around the inhibition of sheddase function.

Tumor necrosis factor alpha converting enzyme (TACE) is a sheddase protein that has been observed in many types of cancer and could serve as an important Biomarker (medicine) used in the detection of cancer. [5] While the expression of TACE does not directly correlate with particular stages of cancer, the shedding activity of the enzyme is significantly more prominent in head and neck cancer cells compared to normal cultured cells. [5]

See also

Related Research Articles

Tumor necrosis factor

Tumor necrosis factor is a cytokine, i.e. a small protein used by the immune system for cell signaling. If macrophages detect an infection, they release TNF in order to alert other cells of the immune system as well as cells of other tissues, leading to inflammation.

Fas ligand

Fas ligand is a type-II transmembrane protein that belongs to the tumor necrosis factor (TNF) family. Its binding with its receptor induces apoptosis. Fas ligand/receptor interactions play an important role in the regulation of the immune system and the progression of cancer.

ICAM-1

ICAM-1 also known as CD54 is a protein that in humans is encoded by the ICAM1 gene. This gene encodes a cell surface glycoprotein which is typically expressed on endothelial cells and cells of the immune system. It binds to integrins of type CD11a / CD18, or CD11b / CD18 and is also exploited by rhinovirus as a receptor for entry into respiratory epithelium.

ADAM (protein)

ADAMs are a family of single-pass transmembrane and secreted metalloendopeptidases. All ADAMs are characterized by a particular domain organization featuring a pro-domain, a metalloprotease, a disintegrin, a cysteine-rich, an epidermal-growth factor like and a transmembrane domain, as well as a C-terminal cytoplasmic tail. Nonetheless, not all human ADAMs have a functional protease domain, which indicates that their biological function mainly depends on protein–protein interactions. Those ADAMs which are active proteases are classified as sheddases because they cut off or shed extracellular portions of transmembrane proteins. For example, ADAM10 can cut off part of the HER2 receptor, thereby activating it. ADAM genes are found in animals, choanoflagellates, fungi and some groups of green algae. Most green algae and all land plants likely lost ADAM proteins.

TNF receptor superfamily

The tumor necrosis factor receptor superfamily (TNFRSF) is a protein superfamily of cytokine receptors characterized by the ability to bind tumor necrosis factors (TNFs) via an extracellular cysteine-rich domain. With the exception of nerve growth factor (NGF), all TNFs are homologous to the archetypal TNF-alpha. In their active form, the majority of TNF receptors form trimeric complexes in the plasma membrane. Accordingly, most TNF receptors contain transmembrane domains (TMDs), although some can be cleaved into soluble forms, and some lack a TMD entirely. In addition, most TNF receptors require specific adaptor protein such as TRADD, TRAF, RIP and FADD for downstream signalling. TNF receptors are primarily involved in apoptosis and inflammation, but they can also take part in other signal transduction pathways, such as proliferation, survival, and differentiation. TNF receptors are expressed in a wide variety of tissues in mammals, especially in leukocytes.

Fas receptor

The Fas receptor, also known as Fas, FasR, apoptosis antigen 1, cluster of differentiation 95 (CD95) or tumor necrosis factor receptor superfamily member 6 (TNFRSF6), is a protein that in humans is encoded by the FAS gene. Fas was first identified using a monoclonal antibody generated by immunizing mice with the FS-7 cell line. Thus, the name Fas is derived from FS-7-associated surface antigen.

Death-inducing signaling complex

The death-inducing signaling complex or DISC is a multi-protein complex formed by members of the "death receptor" family of apoptosis-inducing cellular receptors. A typical example is FasR, which forms the DISC upon trimerization as a result of its ligand (FasL) binding. The DISC is composed of the death receptor, FADD, and caspase 8. It transduces a downstream signal cascade resulting in apoptosis.

ADAM17

ADAM metallopeptidase domain 17 (ADAM17), also called TACE, is a 70-kDa enzyme that belongs to the ADAM protein family of disintegrins and metalloproteases.

Growth hormone-binding protein (GHBP) is a soluble carrier protein for growth hormone (GH). The function of GHBP is still unknown. Current research suggests that the protein is associated with regulation of the GH supply in the circulatory system as well as GH receptor function.

Alpha secretase

Alpha secretases are a family of proteolytic enzymes that cleave amyloid precursor protein (APP) in its transmembrane region. Specifically, alpha secretases cleave within the fragment that gives rise to the Alzheimer's disease-associated peptide amyloid beta when APP is instead processed by beta secretase and gamma secretase. The alpha-secretase pathway is the predominant APP processing pathway. Thus, alpha-secretase cleavage precludes amyloid beta formation and is considered to be part of the non-amyloidogenic pathway in APP processing. Alpha secretases are members of the ADAM family, which are expressed on the surfaces of cells and anchored in the cell membrane. Several such proteins, notably ADAM10, have been identified as possessing alpha-secretase activity. Upon cleavage by alpha secretases, APP releases its extracellular domain - a fragment known as APPsα - into the extracellular environment in a process known as ectodomain shedding.

Syndecan

Syndecans are single transmembrane domain proteins that are thought to act as coreceptors, especially for G protein-coupled receptors. More specifically, these core proteins carry three to five heparan sulfate and chondroitin sulfate chains, i.e. they are proteoglycans, which allow for interaction with a large variety of ligands including fibroblast growth factors, vascular endothelial growth factor, transforming growth factor-beta, fibronectin and antithrombin-1. Interactions between fibronectin and some syndecans can be modulated by the extracellular matrix protein tenascin C.

CD27

CD27 is a member of the tumor necrosis factor receptor superfamily. It is currently of interest to immunologists as a co-stimulatory immune checkpoint molecule.

Lymphotoxin alpha

Lymphotoxin-alpha (LT-α) or tumor necrosis factor-beta (TNF-β) is a protein that in humans is encoded by the LTA gene. Belonging to the hematopoietic cell line, LT-α exhibits anti-proliferative activity and causes the cellular destruction of tumor cell lines. As a cytotoxic protein, LT-α performs a variety of important roles in immune regulation depending on the form that it is secreted as. Unlike other members of the TNF superfamily, LT-α is only found as a soluble homotrimer, when found at the cell surface it is found only as a heterotrimer with LTβ.

CD163

CD163 is a protein that in humans is encoded by the CD163 gene. CD163 is the high affinity scavenger receptor for the hemoglobin-haptoglobin complex and in the absence of haptoglobin - with lower affinity - for hemoglobin alone. It also is a marker of cells from the monocyte/macrophage lineage. CD163 functions as innate immune sensor for gram-positive and gram-negative bacteria. The receptor was discovered in 1987.

ADAM10

A Disintegrin and metalloproteinase domain-containing protein 10, also known as ADAM10 or CDw156 or CD156c is a protein that in humans is encoded by the ADAM10 gene.

PTPRK

Receptor-type tyrosine-protein phosphatase kappa is an enzyme that in humans is encoded by the PTPRK gene. PTPRK is also known as PTPkappa and PTPκ.

Angiogenesis is the process of forming new blood vessels from existing blood vessels. It is a highly complex process involving extensive interplay between cells, soluble factors, and the extracellular matrix (ECM). Angiogenesis is critical during normal physiological development, but it also occurs in adults during inflammation, wound healing, ischemia, and in pathological conditions such as rheumatoid arthritis, hemangioma, and tumor growth. Proteolysis has been indicated as one of the first and most sustained activities involved in the formation of new blood vessels. Numerous proteases including matrix metalloproteases (MMPs), a disintegrin and metalloprotease domain (ADAM), a disintegrin and metalloprotease domain with throbospondin motifs (ADAMTS), and cysteine and serine proteases are involved in angiogenesis. This article focuses on the important and diverse roles that these proteases play in the regulation of angiogenesis.

ADAM 17 endopeptidase is an enzyme. This enzyme catalyses the following chemical reaction

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Soluble tumor necrosis factor receptors (sTNFR) are the cleaved-off extracellular domains of transmembrane TNF receptors. They are proposed to enter the bloodstream either via shedding by the enzyme TACE or through exocytosis of the full-length receptor in exosome-like vesicles. Elevated levels of sTNFR are seen in inflammatory processes such as infection, malignancy and autoimmune diseases.

References

  1. R&D Systems (Winter 2006). "Need help at the cell surface? Ask your local sheddase". Cytokine Bulletin.
  2. Healthvalue: Sheddases and ADAMs
  3. Sommer, Anselm; Kordowski, Felix; Büch, Joscha; Maretzky, Thorsten; Evers, Astrid; Andrä, Jörg; Düsterhöft, Stefan; Michalek, Matthias; Lorenzen, Inken (2016-05-10). "Phosphatidylserine exposure is required for ADAM17 sheddase function". Nature Communications. 7. doi:10.1038/ncomms11523. ISSN   2041-1723. PMC   4866515 . PMID   27161080.
  4. "ADAM10 is a principal 'sheddase' of the low-affinity immunoglobulin E receptor CD23" (PDF). Retrieved November 5, 2016.
  5. 1 2 "Sheddase Activity of Tumor Necrosis Factor- Converting Enzyme Is Increased and Prognostically Valuable in Head and Neck Cancer" . Retrieved 2016-11-05.