FKBP14 is a gene which codes for a structural protein named FKBP prolyl isomerase 14. [1] [2] This protein is believed to aid in the process of procollagen folding and is located in the endoplasmic reticulum that functions to process and transport proteins. Procollagens are collagen precursors located in the extracellular matrix that give tissues elasticity, strength, and support. This gene is involved in patterning the collagen structure. FKBP prolyl isomerase 14 may also be involved in altering other factors in the extracellular matrix. Mutations of this gene are associated with the kyphoscoliotic type of Ehlers-Danlos syndrome. [3] This condition is characterized by a high range of joint movement, muscle atrophy, curved spine, and delicate cardiovascular vessels. These symptoms are brought about by a loss of the protein which results in a disruption of endoplasmic reticulum activities and extracellular matrix organization. FKBP14 mRNA levels are found higher in ovarian cancer tissues than healthy ovarian tissue and knocked down expression of FKBP14 by lentiviral shRNA leads to an impaired proliferative ability of ovarian cancer cells. [4]
Collagen is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole-body protein content. Collagen consists of amino acids bound together to form a triple helix of elongated fibril known as a collagen helix. It is mostly found in connective tissue such as cartilage, bones, tendons, ligaments, and skin.
Ehlers–Danlos syndromes (EDS) are a group of 13 genetic connective-tissue disorders in the current classification, with a 14th type discovered in 2018. Symptoms include loose joints, joint pain, stretchy velvety skin, and abnormal scar formation. These may be noticed at birth or in early childhood. Complications may include aortic dissection, joint dislocations, scoliosis, chronic pain, or early osteoarthritis.
In biology, the extracellular matrix (ECM), also called intercellular matrix, is a three-dimensional network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide structural and biochemical support to surrounding cells. Because multicellularity evolved independently in different multicellular lineages, the composition of ECM varies between multicellular structures; however, cell adhesion, cell-to-cell communication and differentiation are common functions of the ECM.
Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to which the glycosaminoglycan is joined through a tetrasaccharide bridge. The Ser residue is generally in the sequence -Ser-Gly-X-Gly-, although not every protein with this sequence has an attached glycosaminoglycan. The chains are long, linear carbohydrate polymers that are negatively charged under physiological conditions due to the occurrence of sulfate and uronic acid groups. Proteoglycans occur in connective tissue.
A disintegrin and metalloproteinase with thrombospondin motifs 2 (ADAM-TS2) also known as procollagen I N-proteinase is an enzyme that in humans is encoded by the ADAMTS2 gene.
Collagen, type I, alpha 1, also known as alpha-1 type I collagen, is a protein that in humans is encoded by the COL1A1 gene. COL1A1 encodes the major component of type I collagen, the fibrillar collagen found in most connective tissues, including cartilage.
Lysyl hydroxylases are alpha-ketoglutarate-dependent hydroxylases enzymes that catalyze the hydroxylation of lysine to hydroxylysine. Lysyl hydroxylases require iron and vitamin C as cofactors for their oxidation activity. It takes place following collagen synthesis in the cisternae (lumen) of the rough endoplasmic reticulum (ER). There are three lysyl hydroxylases (LH1-3) encoded in the human genome, namely: PLOD1, PLOD2 and PLOD3. From PLOD2 two splice variant can be expressed, where LH2b differs from LH2a by incorporating the small exon 13A. LH1 and LH3 hydroxylate lysyl residues in the collagen triple helix, whereas LH2b hydroxylates lysyl residues in the telopeptides of collagen. In addition to its hydroxylation activity, LH3 has glycosylation activity that produces either monosaccharide (Gal) or disaccharide (Glc-Gal) attached to collagen hydroxylysines.
Type III Collagen is a homotrimer, or a protein composed of three identical peptide chains (monomers), each called an alpha 1 chain of type III collagen. Formally, the monomers are called collagen type III, alpha-1 chain and in humans are encoded by the COL3A1 gene. Type III collagen is one of the fibrillar collagens whose proteins have a long, inflexible, triple-helical domain.
A member of the tenascin family, tenascin X (TN-X) also known as flexillin or hexabrachion-like protein is a 450kDa glycoprotein that is expressed in connective tissues. TN-X possesses a modular structure composed, from the N- to the C-terminal part by a Tenascin assembly domain (TAD), a series of 18.5 repeats of epidermal growth factor (EGF)-like motif, a high number of Fibronectin type III (FNIII) module, and a fibrinogen (FBG)-like globular domain. In humans, tenascin X is encoded by the TNXB gene.
Collagen alpha-1(V) chain is a protein that in humans is encoded by the COL5A1 gene.
Collagen alpha-2(V) chain is a protein that in humans is encoded by the COL5A2 gene.
Procollagen-proline dioxygenase, commonly known as prolyl hydroxylase, is a member of the class of enzymes known as alpha-ketoglutarate-dependent hydroxylases. These enzymes catalyze the incorporation of oxygen into organic substrates through a mechanism that requires alpha-Ketoglutaric acid, Fe2+, and ascorbate. This particular enzyme catalyzes the formation of (2S, 4R)-4-hydroxyproline, a compound that represents the most prevalent post-translational modification in the human proteome.
Peptidyl-prolyl cis-trans isomerase B is an enzyme that is encoded by the PPIB gene. As a member of the peptidyl-prolyl cis-trans isomerase (PPIase) family, this protein catalyzes the cis-trans isomerization of proline imidic peptide bonds, which allows it to regulate protein folding of type I collagen. Generally, PPIases are found in all eubacteria and eukaryotes, as well as in a few archaebacteria, and thus are highly conserved.
Protein disulfide-isomerase, also known as the beta-subunit of prolyl 4-hydroxylase (P4HB), is an enzyme that in humans encoded by the P4HB gene. The human P4HB gene is localized in chromosome 17q25. Unlike other prolyl 4-hydroxylase family proteins, this protein is multifunctional and acts as an oxidoreductase for disulfide formation, breakage, and isomerization. The activity of P4HB is tightly regulated. Both dimer dissociation and substrate binding are likely to enhance its enzymatic activity during the catalysis process.
Procollagen-lysine,2-oxoglutarate 5-dioxygenase 3 is an enzyme that in humans is encoded by the PLOD3 gene.
Peptidyl-prolyl cis-trans isomerase C (PPIC) is an enzyme that in humans is encoded by the PPIC gene on chromosome 5. As a member of the peptidyl-prolyl cis-trans isomerase (PPIase) family, this protein catalyzes the cis-trans isomerization of proline imidic peptide bonds, which allows it to facilitate folding or repair of proteins. In addition, PPIC participates in many biological processes, including mitochondrial metabolism, apoptosis, redox, and inflammation, as well as in related diseases and conditions, such as ischemic reperfusion injury, AIDS, and cancer.
FK506-binding protein 10 is a protein that in humans is encoded by the FKBP10 gene.
Cranio-lenticulo-sutural dysplasia is a neonatal/infancy disease caused by a disorder in the 14th chromosome. It is an autosomal recessive disorder, meaning that both recessive genes must be inherited from each parent in order for the disease to manifest itself. The disease causes a significant dilation of the endoplasmic reticulum in fibroblasts of the host with CLSD. Due to the distension of the endoplasmic reticulum, export of proteins from the cell is disrupted.
Bruck syndrome is characterized as the combination of arthrogryposis multiplex congenita and osteogenesis imperfecta. Both diseases are uncommon, but concurrence is extremely rare which makes Bruck syndrome very difficult to research. Bruck syndrome is thought to be an atypical variant of osteogenesis imperfecta most resembling type III, if not its own disease. Multiple gene mutations associated with osteogenesis imperfecta are not seen in Bruck syndrome. Many affected individuals are within the same family, and pedigree data supports that the disease is acquired through autosomal recessive inheritance. Bruck syndrome has features of congenital contractures, bone fragility, recurring bone fractures, flexion joint and limb deformities, pterygia, short body height, and progressive kyphoscoliosis. Individuals encounter restricted mobility and pulmonary function. A reduction in bone mineral content and larger hydroxyapatite crystals are also detectable Joint contractures are primarily bilateral and symmetrical, and most prone to ankles. Bruck syndrome has no effect on intelligence, vision, or hearing.
Daniel S. Greenspan is an American biomedical scientist, academic and researcher. He is Kellett professor of Cell and Regenerative Biology at the University of Wisconsin-Madison School of Medicine and Public Health. He has authored over 120 publications. His research has mainly focused on genes encoding proteins of the extracellular space and possible links between defects in such genes and human development and disease.