Cēsis (Latvian pronunciation: [tseːsis]), (German: Wenden, Livonian: Venden, Estonian: Võnnu, Polish: Kieś, Russian: Цесис Tsesis) is a town in Latvia located in the northern part of the Central Vidzeme Upland. Cēsis is on the Gauja River valley, and is built on a series of ridges above the river overlooking the woods below. Cēsis was one of the candidate cites for the title of European Capital of Culture 2014 (Riga was the Latvian city that won the title).
The oldest settlement in Cēsis is the hill fort on Riekstu hill, a fortified wooden castle built by a tribe known as the Vends. The 18 m (59.06 ft) high mound with its partly preserved fortification system can still be seen in the Castle Park. This settlement was located near major trade routes from west to east and dominated the regional countryside.
Platelet-derived growth factor subunit B is a protein that in humans is encoded by the PDGFB gene.
The protein encoded by this gene is a member of the platelet-derived growth factor family. The four members of this family are mitogenic factors for cells of mesenchymal origin and are characterized by a motif of eight cysteines. This gene product can exist either as a homodimer (PDGF-BB) or as a heterodimer with the platelet-derived growth factor alpha (PDGFA) polypeptide (PDGF-AB), where the dimers are connected by disulfide bonds.
Mutations in this gene are associated with meningioma. Reciprocal translocations between chromosomes 22 and 17, at sites where this gene and that for COL1A1 are located, are associated with a particular type of skin tumor called dermatofibrosarcoma protuberans resulting from unregulated expression of growth factor. Two splice variants have been identified for this gene.
Platelet-derived growth factor (PDGF) is one of the numerous growth factors, or proteins that regulate cell growth and division. In particular, it plays a significant role in blood vessel formation (angiogenesis), the growth of blood vessels from already-existing blood vessel tissue. Uncontrolled angiogenesis is a characteristic of cancer. In chemical terms, platelet-derived growth factor is a dimeric glycoprotein composed of two A (-AA) or two B (-BB) chains or a combination of the two (-AB).
PDGF is a potent mitogen for cells of mesenchymal origin, including fibroblasts, smooth muscle cells and glial cells. In both mouse and human, the PDGF signalling network consists of four ligands, PDGFA-D, and two receptors, PDGFRalpha and PDGFRbeta. All PDGFs function as secreted, disulphide-linked homodimers, but only PDGFA and B can form functional heterodimers.
Though PDGF is synthesized, stored (in the alpha granules of platelets), and released by platelets upon activation, it is also produced by a plethora of cells including smooth muscle cells, activated macrophages, and endothelial cells