Search results

PLGF is a growth factor active in angiogenesis, and endothelial cell growth, stimulating their proliferation and migration. It binds to receptor vegfr-1/flt1.

Transferrin is the iron-transport protein of vertebrate serum and donates iron to cells through interaction with a specific membrane receptor, CD71. Transferrin appears to be indispensable for most cells growing in tissue culture.
It is referred to frequently as a growth factor because, in analogy to other growth factor-receptor interactions, proliferating cells express high numbers of transferrin receptors, and the binding of transferrin to their receptors is needed for cells to initiate and maintain their DNA synthesis. Apart from its role as an iron transport protein transferrin acts as a cytokine and has functions that may not be related to its iron-carrying capacity.

Hepatocyte Growth Factor (HGF) is a multifunctional growth factor which regulates both cell growth and cell motility. It exerts a strong mitogenic effect on hepatocytes and primary epithelial cells. HGF synergizes with Interleukin-3 and GM-CSF to stimulate colony formation of hematopoietic progenitor cells in vitro and may, therefore, also modulate hematopoiesis.

The cytokine Macrophage migration inhibitory factor (MIF) has been identified to be secreted by the pituitary gland and the monocyte/macrophage and to play an important role in endotoxic shock. MIF has the unique property of being released from macrophages and T cells in response to physiological concentrations of glucocorticoids. The secretion of MIF is tightly regulated and decreases at high, anti-inflammatory steroid concentration.

NAT6 is an enzyme that catalyzes the transfer of acetyl groups from acetyl-CoA to acrylamines. NAT6 is located mainly in the cytoplasm and its activity has been recognized by its feasibility to acetylate the N-terminus of proteins using a ping-pong-like mechanism and by its substrate specificity. Given that the NAT6 gene maps to the chromosomal region 3p21.3, which includes at least one tumor suppressor gene, the function of NAT6 plays an important role in cancer.

The gene for TNFRSF12A was initially recognized as a fibroblast growth factor inducible immediate early response gene Fn14 in mouse NIH 3T3 fibroblasts. Human TNFRSF12A cDNA encodes a 129 amino acid residue type I transmembrane protein with a 27 aa signal peptide, a 53 aa extracellular domain, a 21 aa transmembrane domain and a 28 aa cytoplasmic domain. Human and mouse TNFRSF12A hold 82% aa sequence identity. TNFRSF12 is the tiniest member of the TNF receptor superfamily and has only one cysteine rich region in its extracellular domain. The TNFRSF12A cytoplasmic domain holds one TRAF binding motif which binds TRAFs 1, 2, and 3. TNFRSF12A binds its ligand TWEAK/TNFSF12A with high affinity to initiate a signal transduction cascade which subject to the cell type, causes different cellular responses such as cell death, cell proliferation, and angiogenesis.

DFF is a heterodimeric protein of 40kDa (DFFB) and 45kDa (DFFA) subunits. DFFA (DNA fragmentation factor subunit alpha) is the substrate for caspase-3 and triggers DNA fragmentation during apoptosis. DFF is activated once DFFA is cleaved by caspase-3. The cleaved fragments of DFFA detach from DFFB (the active component of DFF), which in turn triggers DNA fragmentation as well as chromatin condensation during apoptosis. Apoptosis is accompanied by shrinkage and fragmentation of the cells and nuclei and degradation of the chromosomal DNA into nucleosomal units.
A reduced level of DFFA detected in ovarian endometriosis may be a part of an apoptosis-resistant mechanism enhancing the disease progression.
DFFA at chromosome 1 shows rare allelic variants in neuroblastoma tumors.

Nucleolin (NCL) which is a eukaryotic nucleolar phosphoprotein, involved in the synthesis and maturation of ribosomes. Nucleolin is the key nucleolar protein of growing eukaryotic cells. NCL is found linked with intranucleolar chromatin and pre-ribosomal particles. NCL induces chromatin decondensation by binding to histone H1. Nucleolin is assumed to have a role in pre-rRNA transcription and ribosome compilation. Nucleolin may also have a role in the process of transcriptional elongation. Nucleolin is located primarily in the dense fibrillar regions of the nucleolus. The Human NCL gene consists of 14 exons with 13 introns and spans approximately 11kb.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.

Transforming growth factor betas (TGF Betas) mediate many cell-cell interactions that occur during embryonic development. Three TGF Betas have been identified in mammals. TGF Beta 1, TGF Beta 2 and TGF Beta 3 are each synthesized as precursor proteins that are very similar in that each is cleaved to yield a 112 amino acid polypeptide that remains associated with the latent portion of the molecule.

FGF-basic is a member of the fibroblast growth factor (FGF) family. FGF family members bind heparin and possess broad mitogenic and angiogenic activities. This protein has been implicated in diverse biological processes, such as limb and nervous system development, wound healing, and tumor growth. The mRNA for this gene contains multiple polyadenylation sites, and is alternatively translated from AUG and non-AUG (CUG) initiation codons resulting in 5 different isoforms with distinct properties. The CUG-initiated isoforms are localized in the nucleus and are responsible for the intracrine effect, whereas, the AUG-initiated form is mostly cytosolic and is responsible for the paracrine and autocrine effects of this FGF.
The heparin-binding growth factors are angiogenic agents in vivo and are potent mitogens for a variety of cell types in vitro. there are differences in the tissue distribution and concentration of these 2 growth factors.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), and VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes. All VEGF-receptors have seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular split tyrosine kinase domain. VEGFR-2 has a lower affinity for VEGF than the Flt-1 receptor, but a higher signalling activity. Mitogenic activity in endothelial cells is mainly mediated by VEGFR-2 leading to their proliferation. Differential splicing of the flt-1 gene leads to the formation of a secreted, soluble variant of VEGFR-1 (sVEGFR-1). No naturally occurring, secreted forms of VEGFR-2 have so far been reported. The binding of VEGF165 to VEGFR-2 is dependent on heparin.

The cytokine Macrophage migration inhibitory factor (MIF) has been identified to be secreted by the pituitary gland and the monocyte/macrophage and to play an important role in endotoxic shock. MIF has the unique property of being released from macrophages and T cells in response to physiological concentrations of glucocorticoids. The secretion of MIF is tightly regulated and decreases at high, anti-inflammatory steroid concentration.

Prolactin is a lactogenic hormone secreted by the adenohypophysis .Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation.Prolactin has been shown also to have cytokine-like activities and to have important immunoregulatory activities. It contributes to the development of lymphoid tissues and the maintenance of physiological immune function and also modulates a variety of T-cell immune responses. Prolactin has been reported to activate cellular proliferation in nonreproductive tissue, such as liver, spleen, and thymus. It induces significant proliferation in aortic smooth muscle cells and also enhances proliferation of these cells induced by PDGF . Prolactin also appears to be directly mitogenic for pancreatic beta cells. Prolactin is also mitogenic for cultured astrocytes.

TNF Ligand Receptor Superfamily Member 25 (TNFRSF25) belongs to the TNF receptor superfamily that binds to the TNF-like protein TL1A. TNFRSF25 interacts directly with the adapter TRADD and regulates lymphocyte homeostasis. TNFRSF25 is also mediates activation of NF-kappa-B and induces apoptosis. TNFRSF25 signals are vital to exert T helper cell 2 effector activity in Th2-polarized CD4 cells and co-stimulate interleukin-13 production by glycosphingolipid-activated NKT cells.

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).

C3 is central to the activation of all 3 pathways of complement activation. Initiation of each pathway generates proteolytic enzyme complexes which binds the target surface. These enzymes cleave a peptide bond in C3 releasing the anaphylatoxin C3a and activating C3b. Most of the C3 activated during complement activation never attaches to the surface due to its thioester reaction with water forming fluid phase C3b which is rapidly inactivated by factors H and I forming iC3b. Surface-bound C3b is necessary in all 3 pathways for efficient activation of C5 and formation of C5b-9 complexes that lyse the target cell membrane.

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. Human 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 human 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 human VEGF-C is also a mitogen for vascular endothelial cells, it is much less potent than VEGF-A.

Filamin is a large (270kd) dimeric actin crosslinking protein from a variety of sources, which helps to stabilize the 3D cortical actin network. The fundamental structure of filamin is well conserved and consists of an actin binding domain at the N-terminus followed by a C-terminal rod domain consisting of numerous repeat segments ranging from 4 in C. elegans to 24 in mammalian cells. Each repeat in the rod domain consists of roughly 100 residues and forms an immunoglobulin like fold. Such immunoglobulin folds have been found in a variety of proteins and are responsible for protein-protein interactions. Filamin Human actin-binding protein (ABP), aka filamin, crosslinks actin filaments into orthogonal networks in cortical cytoplasm and participates in the anchoring of membrane proteins for the actin cytoskeleton. Mammalian filamin interacts directly with at least 30 proteins such as transmembrane receptors, second messenger-associated proteins, protein kinases, phosphatases and cytoskeletal proteins and these interactions have been shown to require one or more of the repeat elements in the rod domain.

NUTF2 assists in protein transport into the nucleus and interacts with the nucleoporin p62 and with Ran. NUTF2 plays a role at a relatively late stage of nuclear protein import, subsequent to the initial docking of nuclear import ligand at the nuclear envelope. NUTF2 is part of a multicomponent system of cytosolic factors that come together at the pore complex during nuclear import.

Epidermal growth factor has a profound effect on the differentiation of specific cells in vivo and is a potent mitogenic factor for a variety of cultured cells of both ectodermal and mesodermal origin. The EGF precursor is believed to exist as a membrane-bound molecule which is proteolytically cleaved to generate the 53-amino acid peptide hormone that stimulates cells to divide. EGF stimulates the growth of various epidermal and epithelial tissues in vivo and in vitro and of some fibroblasts in cell culture.

COAA is a member of the prokaryotic pantothenate kinase family and it is the first enzyme in the Coenzyme A biosynthetic pathway. COAA phosphorylates pantothenate (vitamin B5) to form 4'-phosphopantothenate. The key factor controlling the intracellular CoA concentration is the regulation of COAA activity by feedback inhibition.