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Neuregulin/Heregulin is a family of structurally related polypeptide growth factors which are stemmed from alternatively spliced genes (NRG1, NRG2, NRG3 and NRG4). Thus far, there are more than 14 soluble and transmembrane proteins derived from the NRG1 gene. Proteolytic processing of the extracellular domain of the transmembrane NRG1 isoforms release soluble growth factors. These isoforms contain the heregulins (HRGs), glial growth factors (GGFs) and sensory and motor neuron-derived factor (SMDF). All these factors have the Ig and EGF-like domain, and are able to bind to ErbB3 and ErbB4 receptor tyrosin kinases. This binding stimulates erb3 and erb4 heterodimerization with erb2, promoting intrinsic kinase activity, which results in tyrosine phosphorylation. NRG1 isoforms act to induce the growth and differentiation of epithelial, neuronal, glial, and other types of cells.

Osteopontin is a glycoprotein that was primarilyfound in osteoblasts and takes part in bone remodeling, immune functions in fibroblasts, macrophages, & lymphocytes during inflammation and wound healing. SPP1 highlybinds to hydroxyapatite. SPP1 forms an integral part of the mineralized matrix. SPP1 is vital to cell-matrix interaction.
Secreted Phosphoprotein-1 protects against cardiac ischemia-reperfusion injury through late preconditioning. Expression of Ostepontin and CD44 in hepatocellular carcinoma is linked to advanced tumor stage &leads to prognosis information. SPP1 is the most over-expressed gene in intrahepatic cholangiocarcinoma. Secreted Phosphoprotein-1 overexpression is related with interstitial lung diseases.

Interleukin-1 ra is a member of the interleukin 1 cytokine family. This protein inhibits the activities of interleukin 1, alpha (IL1A) and interleukin 1, beta (IL1B), and modulates a variety of interleukin 1 related immune and inflammatory responses. This gene and five other closely related cytokine genes form a gene cluster spanning approximately 400 kb on chromosome 2. A polymorphism of this gene is reported to be associated with increased risk of osteoporotic fractures and gastric cancer. Four alternatively spliced transcript variants encoding distinct isoforms have been reported.

Interleukin-1b is produced by activated macrophages, IL-1B stimulates thymocyte proliferation by inducing il-2 release, b-cell maturation and proliferation, and fibroblast growth factor activity. IL1B proteins are involved in the inflammatory response, being identified as endogenous pyrogens, and are reported to stimulate the release of prostaglandin and collagenase from synovial cells.

Factor IX is a glycoprotein, which is synthesized in the liver. The domain structure of factor IX is similar to that of the other vitamin K dependent coagulation factors. The NH2-terminal region contains 12 g-carboxyglutamic acid (gla) residues, which facilitate the calcium dependent binding of factor IX to negatively charged phospholipid surfaces. Two domains which are homologous to epidermal growth factor (EGF) span the region between the NH2-terminal gla domain and the activation peptide (Ala-146 to Arg-180). Factor IX is activated by either factor XIa or the factor VIIa/tissue factor/phospholipid complex. Cleavage at site A yields the intermediate IXa, which is subsequently converted to the fully active form IXab by cleavage at site B. The NH2-terminal light chain (GLA and EGF domains) remains covalently attached to the COOH-terminal heavy chain by a disulfide bond. The serine protease catalytic triad (Ser-365, His 221, Asp-269) is located in the heavy chain. Factor IXab is the catalytic component of the “intrinsic factor Xase complex” (factor VIIIa/IXa/Ca2+/phospholipid) which proteolytically activates factor X to factor Xa.

IFN-alpha is produced by macrophages, IFN-alpha has antiviral activities and stimulates the production of two enzymes: a protein kinase and an oligoadenylate synthetase.

Adiponectin is an important negative regulator in hematopoiesis and immune systems. It may be involved in ending inflammatory responses through its inhibitory functions. Inhibits endothelial nf-kappa-b signaling through a camp-dependent pathway. Inhibits tnf-alpha- induced expression of endothelial adhesion molecules. Involved in the control of fat metabolism and insulin sensitivity.

Antigen 85A is a member of the antigen 85 complex (Antigen 85A, B, C). The enzymes of the antigen 85 complex have mycolyltransferase activity and catalyze the synthesis of the very rich glycolipid of the mycobacterial cell wall, the cord factor (trehalose 6,6'-dimycolate, TDM). The cord factor is vital for the integrity of the mycobacterial cell wall and pathogenesis of the bacillus. TDM is synthesized from two molecules of trehalose-6'-monomycolate (TMM) by Antigen 85A.

The Argonaute protein is part of the RISC or RNA-induced silencing complex, as so, the protein has a key part in the slicing processes of RNA. The RNA interference (RNAi) is being held by RISC. Small non-coding RNA fragments bond to the Argonaute proteins, through base pairing, eventually leads to the cleavage of messenger RNA or translation suppression.

Melanoregulin (MREG) takes part in membrane fusion and in regulating the biogenesis of disk membranes of photoreceptor rods. MREG is expressed in photoreceptor cells as two isoforms as a result of alternative splicing. MREG interacts with Peripherin-2, a photoreceptor specific tetraspanin protein which is required to preserve normal cell structure during the renewal process of membrane fusion. Moreover, MREG plays a part in the incorporation of pigments into hair.

SCG5 also called 7B2 protein is localized in neuroendocrine tissues. SCG5 functions as a chaperone protein for the proprotein convertase PC2 and is essential for the production of an active PC2 enzyme.

There are several proteolytic fragments or specific domains of proteins that act as inhibitors of angiogenesis. These include fragments of plasminogen such as Angiostatin protein kringles 1-4 and kringles 1-5, Endostatin, Restin, PEX, the N-terminal fragment of prolactin, and the Nterminally truncated platelet factor. Angiostatin is a proteolytic protein fragment of plasminogen that is comprised of the first 4 kringle regions. Angiostatin k1-4 prevents the growth of endothelial cells, and its systemic administration inhibits the growth of primary carcinomas in mice. Angiostatin Kringles 1-3 segment has a larger inhibitory activity than the Angiostatin kringles 1-4 fragment. The protease-activated angiostatin kringles 1-5 is the most potent plasminogen fragment with over 50 times larger endothelial cell specific inhibitory activity. Angiostatin kringles 1-5 systemic administration inhibits growth of fibrosarcoma and significantly reduces neovascularization.
Angiostatin is an angiogenesis inhibitor in mouse serum and urine. Angiostatin is a 38 kDa protein fragment of the plasminogen composed of the 1st 4 kringle domains of plasminogen. Angiostatin K1-4 is also named plasminogen kringles 1-4 and PK1-4.
Angiostatin protein is manufactured by the protelytic cleavage of plasminogen by a serine protease from several prostate carcinoma cell lines. The manufacturing of angiostatin by pancreatic cancer cells can be inhibited by TGF-beta 1 along with plasminogen activator inhibitor type-1 (PAI1).

Sorting nexin-5 (SNX5) belongs to the sorting nexin family, whose members contains a phox (PX) domain, (which is a phosphoinositide binding domain) and are involved in intracellular trafficking. SNX5 protein is a component of the mammalian retromer complex, which facilitates cargo recovery from endosomes to the trans-Golgi network. SNX5 binds to the Fanconi anemia, complementation group A protein.

Pleckstrin homology-like domain family A member 2 (PHLDA2) is a cytoplasmic protein, which is involved in fetal and placental growth. PHLDA2 is an apoptosis-related protein, which acts as a negative growth regulator and is expressed during normal human development. PHLDA2 is imprinted on placenta, liver and fetal tissues during embryogenesis and is removed once development is complete. The PHLDA2 gene is one of a number of genes in the imprinted gene domain of 11p15.5 which is considered to be an important tumor suppressor gene region. Changes in this region may be linked to the Beckwith-Wiedemann syndrome, Wilms tumor, rhabdomyosarcoma, adrenocortical carcinoma, and lung, ovarian, and breast cancer. PHLDA2 is expressed in placenta (present in all cells of the villous cytotrophoblast) and adult prostate gland. Furthermore, PHLDA2 is expressed in adult brain and neuroblastoma, medullablastoma and glioblastoma cell lines and at low levels in adult liver and lung, and fetal liver.

Chemokine (C-X-C motif) ligand 10 (CXCL10) is a small cytokine belonging to the CXC chemokine family that is also known as 10 kDa interferon-gamma-induced protein (?-IP10 or IP-10). CXCL10 is secreted by several cell types in response to IFN-?. These cell types include monocytes, endothelial cellsand fibroblasts. CXCL10 has been attributed to several roles, such as chemoattraction for monocytesand T cells, promotion of T cell adhesion to endothelial cells, anti tumor activity, and inhibition of bone marrow colony formation and angiogenesis. The gene for CXCL10 is located on human chromosome 4in a cluster among several other CXC chemokines. This chemokine elicits its effects by binding to the cell surface chemokine receptor CXCR3. The three-dimensional crystal structure of this chemokine has been determined under 3 different conditions to a resolution of up to 1.92A.

All three VEGF receptors belong to the class III subfamily of receptor tyrosine kinases (RTKs) characterised by the seven immunoglobulin-like loops in the extracellular domain. The expression of VEGFR-1 to -3 is almost exclusively restricted to hematopoietic precursor cells, vascular and lymphatic endothelial cells and to the monocyte/macrophage lineage. They play key roles in vasculogenesis, hematopoiesis, angiogenesis and lymphangiogenesis. The FLT-4 cDNA encodes a 1298 amino acid (aa) residue precursor protein with a 23 aa residue signal peptide. Mature VEGFR-3/FLT-4 is composed of a 751 aa residue extracellular domain, a 22 aa transmembrane domain and a 482 aa residue cytoplasmic domain. Both VEGF family members VEGF-C and VEGF-D have been shown to bind and activate VEGFR-3/FLT-4. The Flt-4 gene is widely expressed in the early embryo but becomes restricted to the lymphatic endothelial a latter stages of development. It is important for lymphangiogenesis.

Fibronectin Type III Domain Containing 5 (Irisin) is a newly discovered hormone, secreted into circulation by muscle, which acts on white adipocytes and promotes WAT “browning”. r-Irisin can reduce body weight and cause induction of brown adipocyte in vivo, including a capacity for thermogenic energy expenditure mediated by uncoupling protein 1 (UCP-1). Irisin mature protein is comprised of 110 amino acid residues and two potential glycosylation sites. High levels of Irisin can be found in the heart whereas Very low expression is found in the colon, pancreas and spleen, if any.

Leucine Rich Repeats And Immunoglobulin Like Domains 1 or LRIG1 is a protein, acting as is a pan-negative regulator of EGFR signal transduction. When studied along with ErbB proteins and Met kinase, LRIG1 was found to have regulation activities such as ubiquitination and lysosomal degradation increment of the receptors. Therefore, LRIG1 acts as a suppressor for tumors via cell proliferation control via negative regulation of tyrosine kinase receptors that belongs to the EGF protein family. LRIG1 expression is downregulated in cancer, and acts a prognostic tool for cancer development.

PTX3 is part of the pentraxin family sharing the C-terminal domain with short pentraxins and containing a unique N-terminal domain. PTX3 is produced and released at inflammatory sites by various cell types including monocytes/macrophages, endothelial cells, vascular smooth muscle cells, fibroblasts, and adipocytes. PTX3 is involved in the regulation of innate resistance to pathogens, inflammatory reactions, possibly clearance of self-components and female fertility. PTX3 is used as a marker for disease activity of psoriasis. High serum PTX3 levels are associated with the disease severity of systemic sclerosis. Elevated serum PTX3 is associated with pulmonary fungal infections.

VCAM1 is a member of the Ig superfamily. It is a cell surface sialoglycoprotein expressed by cytokine activated endothelium. VCAM-1 contains 6 or 7 immunoglobulin domains, and is expressed on both large and small vessels only after the endothelial cells are stimulated by cytokines. The protein has a number of functions including the regulation of leukocyte migration, leukocyte endothelial cell adhesion and signal transduction and may play a role in a number of inflammatory diseases (artherosclerosis and rheumatoid arthritis).

Reg protein was shown to be stimulated during the regeneration of pancreatic islets. Since then, many Reg-related proteins have been identified in humans and other animals. In human, the four REG family genes, i.e., REG 1 alpha, REG 1 beta, REG-related sequence (RS) and HIP/PAP, have so far been isolated. These Reg-related proteins are classified into four subfamilies according to their amino-acid sequences, but they share a similar structure and physiological function. Reg protein is a growth factor for pancreatic beta cells and also suggests that the administration of Reg protein could be used as another therapeutic approach for diabetes mellitus. Human REG cDNA which encodes a 166-amino acid protein with a 22-amino acid signal peptide. The amino acid sequence of human REG protein has 68% homology to that of rat Reg protein.
Reg I was found to be expressed mainly in pancreatic beta and acinoductular cells as well as gastric fundic enterochromaffin-like (ECL) cells. Reg I production in ECL cells is stimulated by gastrin, as well as by the proinflammatory cytokine, cytokine-induced neutrophil chemoattractant (CINC)-2Beta. In patients with chronic hypergastrinemia, Reg production is stimulated, with the increased proliferation of gastric mucosal cells. Patients with Helicobacter pylori infection also showed increased Reg production in the gastric mucosa, partly via increased plasma gastrin concentration and partly via increased proinflammatory cytokine production. The serum concentration of the reg-protein was significantly higher in patients with various pancreatic diseases than in normal controls, and was also significantly higher in patients with acute pancreatitis or chronic relapsing pancreatitis than in patients with chronic pancreatitis. Furthermore, the serum PSP/reg-protein concentration was also significantly increased in liver cirrhosis, choledocholithiasis, and various cancers of the digestive system.

Resistin, a product of the RSTN gene, is a peptide hormone belonging to the class of cysteine-rich secreted proteins which is termed the RELM family, and is also described as ADSF (Adipose Tissue- Specific Secretory Factor) and FIZZ3 (Found in Inflammatory Zone). Human resistin contains 108 amino acids as a prepeptide, and its hydrophobic signal peptide is cleaved before its secretion. Resistin circulates in human blood as a dimeric protein consisting of two 92 amino acid polypeptides, which are disulfide-linked via Cys26.
Resistin may be an important link between obesity and insulin resistance. Mouse resistin, specifically produced and secreted by adipocyte, acts on skeletal muscle myocytes, hepatocytes and adipocytes themselves so that it reduces their sensitivity to insulin. Steppan et al. have suggested that resistin suppresses the ability of insulin to stimulate glucose uptake. They have also suggested that resistin is present at elevated levels in blood of obese mice, and is down regulated by fasting and antidiabetic drugs. Way et al., on the other hand, have found that resistin expression is severely suppressed in obesity and is stimulated by several antidiabetic drugs.
Other studies have shown that mouse resistin increases during the differentiation of adipocytes, but it also seems to inhibit adipogenesis. In contrast, the human adipogenic differentiation is likely to be associated with a down regulation of resistin gene expression.