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Activins are homodimers or heterodimers of the different β subunit isoforms, part of the TGFβ family. Mature Activin A has two 116 amino acids residues βA subunits (βA-βA). Activin displays an extensive variety of biological activities, including mesoderm induction, neural cell differentiation, bone remodelling, haematopoiesis, and reproductive physiology. Activins takes part in the production and regulation of hormones such as FSH, LH, GnRH and ACTH. Cells that are identified to express Activin A include fibroblasts, endothelial cells, hepatocytes, vascular smooth muscle cells, macrophages, keratinocytes, osteoclasts, bone marrow monocytes, prostatic epithelium, neurons, chondrocytes, osteoblasts, Leydig cells, Sertoli cells, and ovarian granulosa cells.

SDF-1 (stromal cell-derived factor-1) is small cytokine belonging to the chemokine family that is officially designated Chemokine (C-X-C motif) ligand 12 (CXCL12). It is produced in two forms, SDF-1?/CXCL12a and SDF-1?/CXCL12b, by alternate splicing of the same gene. Chemokines are characterized by the presence of four conserved cysteines, which form two disulfide bonds. The CXCL12 proteins belong to the group of CXC chemokines, whose initial pair of cysteines are separated by one intervening amino acid. CXCL12 is strongly chemotactic for lymphocytes and has been implicated as an important cell co-ordinator during development. During embryogenesis it directs the migration of hematopoietic cells from foetal liver to bone marrow. Mice which were knocked-out for CXCL12 gene were lethal before the birth or within just 1 hour of life. As another role, CXCL12a alters also the electrophysiology of neurons. CXCL12 was shown to be expressend in many tissues in mice (including brain, thymus, heart, lung, liver, kidney, spleen and bone marrow).
The receptor for this chemokine is CXCR4, which was previously called fusin. This CXCL12-CXCR4 interaction used to be considered exclusive (unlike for other chemokines and their receptors), but recently it was suggested that CXCL12 is also bound by CXCR7 receptor. The gene for CXCL12 is located on human chromosome 10. In human and mouse both CXCL12 and CXCR4 show high identity of sequence: 99% and 90%, respectively.

HPCAL1, participates in neuron-specific calcium-binding proteins family found in the retina and brain. HPCAL1 is extremely comparable to human hippocalcin protein and almost equal to the rat and mouse hippocalcin like-1 proteins. HPCAL1 takes part in the calcium-dependent regulation of rhodopsin phosphorylation and can have importance in neuronal signalling in the central nervous system.

Apolipoprotein-D is mainly associated with high density lipoproteins in human plasma. Apolipoprotein-D is an atypical apolipoprotein and, based on its primary structure, Apolipoprotein-D is a member of the lipocalin family. Lipocalins adopt a beta-barrel tertiary structure and transport small hydrophobic ligands. Apolipoprotein-D binds cholesterol, progesterone, pregnenolone, bilirubin and arachidonic acid.
Apolipoprotein-D is expressed in numerous tissues having high levels of expression in spleen, testes and brain. Apolipoprotein-D is present at high concentrations in the cyst fluid of women with gross cystic disease of the breast, a condition associated with increased risk of breast cancer. Apolipoprotein-D accumulates in regenerating peripheral nerves and in the cerebrospinal fluid of patients with neurodegenerative conditions, such as Alzheimer's disease. Apolipoprotein-D participates in maintenance and repair within the central and peripheral nervous systems. Apolipoprotein-D is a multi-ligand, multi-functional transporter and transports a ligand from 1 cell to another within an organ, scavenge a ligand within an organ for transport to the blood or could transport a ligand from the circulation to specific cells within a tissue.

SIRT6 is part of the sirtuin family of proteins (Class IV), homologs to the yeast Sir2 protein. SIRT6 is characterized by a sirtuin core domain. Yeast sirtuin proteins are recognized by their ability to regulate epigenetic gene silencing and suppress recombination of rDNA. SIRT6, a chromatin-associated protein is involved in DNA repair. Human Sirtuins function as intracellular regulatory proteins with mono-ADP-ribosyltransferase activity.

ECSIT homolog (ECSIT) is a ubiquitously expressed protein which has a vital role as an adaptor protein in the cytosolic signal transduction cascade events triggered by Toll receptor activation. ECSIT promotes proteolytic activation of MAP3K1. ECSIT is also involved in the BMP signaling pathway. ECSIT is essential for normal embryonic development. ECSIT was originally classified as a cytoplasmic protein interacting specifically with TNF receptor associated factor (TRAF)-6 in the TLR pathway. ECSIT gene knockdown results in gravely impaired complex I assembly and disrupted mitochondrial function.

SPRY domain-containing SOCS box protein 1 (SPSB1) belongs to the SOCS box protein subfamily. SPSB1 includes a central SPRY domain and a C-terminal SOCS box. Even though, some of the SOCS protein subfamilies function as adaptors for a large family of ubiquitin-protein isopeptide ligases to regulate certain signaling pathways, the function of the SSB subfamily remains to be determined. SPSB1 may have an imperative role in enhancing the HGF-induced Erk-Elk-1-SRE pathway. SPSB1 overexpression exhibited no effect on the basal level or epidermal growth factor-induced SRE-luciferase activity.

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.

ETF is a heterodimer composed of alpha and beta subunit. ETFB protein is electron-transfer-flavoprotein, beta polypeptide that transports electrons between primary flavoprotein dehydrogenases involved in mitochondrial fatty acid and amino acid catabolism and the membrane-bound electron transfer flavoprotein ubiquinone oxidoreductase.

Chromosome 19 Open Reading Frame 80 (C19ORF80) is a significant new regulator of lipid metabolism which regulates serum triglyceride levels, possibly by promoting ANGPTL3 cleavage. C19ORF80 belongs to the ANGPTL protein family. C19ORF80 is a hormone which specifically promotes pancreatic beta cell proliferation and beta cell mass expansion, thus improving glucose tolerance. C19ORF80 is mainly expressed in the liver; it is also expressed in adipose tissues. C19ORF80 is expressed in response to food intake and stimulated by insulin.

Prohibitin (PHB) is an evolutionarily conserved gene that is ubiquitously expressed and which Mutations have been linked to sporadic breast cancer. PHB is thought to be a negative regulator of cell proliferation and may be a tumor suppressor. Prohibitin is expressed as two transcripts with changeable lengths of 3' untranslated region. The longer transcript is present at higher levels in proliferating tissues and cells, proposing that this longer 3' untranslated region functions as a trans-acting regulatory RNA.

Phosphatidylinositol-5-Phosphate 4-Kinase, Type II, Beta (PIP4K2B) belongs to the phosphatidylinositol-4-phosphate 5-kinase family.PIP4K2B catalyzes the phosphorylation of phosphatidylinositol-4-phosphate on the 5th hydroxyl of the myo-inositol ring to form phosphatidylinositol-4,5-bisphosphate. PIP4K2B amino acid sequence does not show resemblance to another kinases although PIP4K2B presents kinase activity.PIP4K2B also interacts with p55 TNF receptor.

CD2 which is also known as E-rosette receptor, T11 and lymphocytefunction antigen-2 (LFA-2) is expressed on T cells, thymocytes, and subset of natural killer cells. Human CD2 functions as the receptor for sheep erythrocytes, human CD58 (LFA-3), and CD15s (Sialyl Lewis X). p56lck, p59fyn, CD3eta and CD3epsilon are tyrosine-phosphorylated after CD2 stimulation. CD2 plays a role in T cell activation, T- or NK-cell-mediated cytolysis, apoptosis in activated peripheral T cells, and regulation of T cell anergy.

Kell blood group glycoprotein homolog or KEL, is an enzyme, part of the zinc endopeptidase of the neprilysin (NEP) group of proteins. KEL has a crucial part in the production of the potent bioactive ET-3, which also includes enzymes that are endothelin convertingenzymes (PEX, XCE, DINE &various NEP-like proteins). KEL uses a single disulfide bond to XK, a gated membranal transporter. The Kell antigen system that includes two proteins, is very crucial among blood group systems.

CD9 which is found on the surface of exosomes is a cell surface glycoprotein which is interacts with integrins and various transmembrane superfamily proteins. CD9 is involved in platelet activation and aggregation and also regulates paranodal junction formation. CD9 takes part in cell adhesion and migration and also promotes muscle cell fusion. CD9 is necessary for the egg-sperm fusion during mammalian fertilization.

TRIM21 is a member of the tripartite motif (TRIM) family. The TRIM motif includes three zinc-binding domains, a RING, a B-box type 1 and a B-box type 2, and a coiled-coil region. The 52 kDa Ro protein is part of the RoSSA ribonucleoprotein, which includes a single polypeptide and one of four small RNA molecules. The RoSSA particle localizes to both the cytoplasm and the nucleus. Ro/SSA interacts with autoantigens in patients with Sjogren syndrome and systemic lupus erythematosus. Ribonucleoprotein particle is composed of a single polypeptide and one of four small RNA molecules. The RoSSA is present in all mammalian cells studied but has no known function. At least 2 isoforms are present in nucleated and red blood cells, and tissue specific differences in Ro/SSA proteins were identified.

Gastric Inhibitory Polypeptide (GIP) which is a significant hormone of the enteroinsular axis has a functional profile of possible therapeutic value for type 2 diabetes. GIP is an important incretin hormone released into the circulation from endocrine K-cells of the duodenum and jejunum after ingestion of food1. GIP was evaluated for his ability to elevate cellular cAMP production. GIP promotes plasma triglyceride clearance in response to oral fat loading.

TSLP protein is a hemopoietic cytokine which signals throughout a heterodimeric receptor complex composed of the thymic stromal lymphopoietin receptor & the Interleukin-7 receptor alpha chain. TSLP impacts myeloid cells thus induces the discharge of T cell-attracting chemokines from monocytes & increases the growth of CD11c(+) dendritic cells. TSLP is mainly expressed in the heart, liver and prostate. TSLP is related in its biological activities with IL-7 and binds with the heterodimeric receptor complex consisting of the Interleukin-7 receptor alpha chain & the TSLPR. Similar to IL-7, TSLP enhances phosphorylation of STAT3 and STAT5, though uses kinases excluding JAKs for its activation. TSLP induces the release of T cell-attracting chemokines such asTARC & MDC from monocytes & triggers CD11c(+) dendritic cells. TSLP activated dendritic cells primes naive T cells to manufacture pro-allergic cytokines such as Iinterleukin-4, Interleukin-5, Interleukin-13 and TNF-alpha whereas down-regulating Interleukin-10 and IFN-gamma play a role in the initiation of allergic inflammation.

Matrix metalloproteinases are a family of zinc and calcium-dependent endopeptidases that break down extracellular matrix proteins. The MMP9 is secreted as a 92kDa zymogen. Cleavage of ProMMP-9 results in the active enzyme, having a molecular weight of approximately 82kDa. MMP9 is composed of the following domains: a gelatin-binding domain consisting of three fibronectin type II units, a catalytic domain containing the zinc-binding site, a proline-rich type V collagen-homologous domain and a hemopexin-like domain. MMP9 is produced by the several cell types: monocytes, macrophages, neutrophils, keratinocytes, fibroblasts, osteoclasts and endothelial cells. MMP9 is involved in inflammatory responses, tissue remodeling, wound healing, tumor growth and metastasis. MMP9 may also play an important part in local proteolysis of the extracellular matrix and in leukocyte migration, as well as in bone osteoclastic resorption. MMP9 cleaves type IV and type V collagens into large C-terminal three quarter fragments and shorter N-terminal one quarter fragments. MMP9 can also degrade fibronectin but not laminin or Pz-peptide.
MMP9 defects may be a cause of susceptibility to intervertebral disc disease (IDD), also known as lumbar disk herniation (LDH).

Chromgranin-A is part of the neuroendocrine secretory protein family. CHGA is located in secretory vesicles of neurons and endocrine cells. Chromgranin-A is a precursor to three biologically active peptides; vasostatin, pancreastatin, and parastatin. These peptides act as autocrine or paracrine negative modulators of the neuroendocrine system. Other peptides, including chromostatin, beta-granin, WE-14 and GE-25, are also derived from the full-length protein. Chromgranin-A has numerous biological activities on some tissues and organs and exerts a large spectrum of homeostatic actions, including antifungal and antimicrobial effect, modulation of cell adhesion, and inhibition of parathyroid hormone secretion.

Glycophorin C, also known as GYPC, is an integral membrane glycoprotein. GYPC is a minor species which is carried by human erythrocytes, however plays an important role in regulating the mechanical stability of red cells. Numeral glycophorin C mutations have been described. The Gerbich and Yus phenotypes are due to deletion of exon 3 & 2, respectively. The Webb & Duch antigens, also identified as glycophorin D, result from single point mutations of the glycophorin C gene. The glycophorin C protein has very slight homology with glycophorins A & B.

Vascular endothelial growth factor is an important signaling protein involved in both vasculogenesis and angiogenesis. As its name implies, VEGF activity has been mostly studied on cells of the vascular endothelium, although it does have effects on a number of other cell types (e.g. stimulation monocyte/ macrophagemigration, neurons, cancer cells, kidney epithelial cells ).VEGF mediates increased vascular permeability, induces angiogenesis, vasculogenesis and endothelial cell growth, promotes cell migration, and inhibits apoptosis. In vitro, VEGF has been shown to stimulate endothelial cell mitogenesisand cell migration. VEGF is also a vasodilator and increases microvascular permeability and was originally referred to as vascular permeability factor.
Elevated levels of this protein are linked to POEMS syndrome, also known as Crow-Fukase syndrome. Mutations in this gene have been associated with proliferative and nonproliferative diabetic retinopathy.

VEGF-C152S is a point mutant generated by the replacement of the second conserved Cys residue of the recombinant processed VEGF-C by a Ser residue. VEGF-C 152S is analog to the human VEGF-C 156S mutant and only active toward VEGFR-3/FLT-4 but, unlike wild type VEGF-C, is unable to bind to and to activate signaling through VEGFR-2/KDR. VEGF-C152S was inactive in the vascular permeability assay and did not increase migration of the capillary endothelial cells, indicating that these VEGF-like effects of VEGF-C require VEGFR-2 binding. VEGF-C, also known as Vascular Endothelial Growth Factor Related Protein (VRP), is a recently discovered VEGF growth factor family member that is most closely related to VEGF-D. The rat VEGF-C cDNA encodes a pre-pro-protein of 416 amino acids residues. It is almost identical to the mouse VEGF-C protein. Similar to VEGF-D, VEGF-C has a VEGF homology domain spanning the middle third of the precursor molecule and long N- and C-terminal extensions. In adults, VEGF-C is highly expressed in heart, placenta, ovary and small intestine. Recombinant rat VEGF-C, lacking the N- and C-terminal extensions and containing only the middle VEGF homology domain, forms primarily non-covalently linked dimers. This protein is a ligand for both VEGFR-2/KDR and VEGFR-3/FLT -4. Since VEGFR-3 is strongly expressed in lymphatic endothelial cells, it has been postulated that VEGF-C is involved in the regulation of the growth and/or differentiation of lymphatic endothelium. Although recombinant rat VEGF-C is also a mitogen for vascular endothelial cells, it is much less potent than VEGF-A.

Thrombopoietin or TPO or MGDF, is a protein (glycoprotein hormone) that can be found in the liver and kidney tissues. TPO regulates the creation of platelets. The protein enhances the production & differentiation of cells such as megakaryocytes that are part of the bone marrow cells that secretes a wide number of platelets. The cellular development process that ends up in the production of platelet calls (Megakaryocytopoiesis). Humoral growth factor is needed for the megakaryocyte proliferation & maturation of megakaryocyte, not apart from thrombopoiesis.