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Peroxisomal Biogenesis Factor 26 (PEX26) which is a part of the peroxin-26 gene family is probably required for protein import into peroxisomes. PEX26 attaches PEX1 and PEX6 to peroxisome membranes to form heteromeric AAA ATPase complexes needed for the import of proteins into peroxisomes. Deficiencies in this gene are the cause of peroxisome biogenesis disorder complementation group 8. PBD is a group of peroxisomal disorders evolving from a failure of protein import into the peroxisomal membrane or matrix.

PEX19 is vital for peroxisome biogenesis in Saccharomyces cerevisiae. PEX19 is limited to the outer surface of peroxisomes in liver cells and is has a part in the early stage of peroxisome membrane assembly, prior to the import of matrix protein.

The peroxisome proliferator activated receptors (PPARs) are ligandactivated transcription factors within the nuclear receptor superfamily, which play important roles in adipogenesis, glucose homeostasis andinflammation. Three different isotypes can be distinguished; alpha, beta and gamma. PPARg, is mainly expressed in adipose tissue and to lesser extent in colon, the immune system and the retina. Whereas PPARg operates in the catabolism of fatty acids in the liver, PPARg influences the storage of fatty acids in the adipose tissue and plays a role in adipocyte differentiation. PPARg binds to DNA as a heterodimer with retinoid X receptor (RXR), activating expression of target genes after binding ligand.

PECI is an enzyme that localized to the peroxisomal matrix and encloses one ACB (acyl-CoA-binding) domain. PECI is expressed abundantly in liver, heart and skeletal muscle. PECI functions to catalyze the isomerization of both 3-cis and 3-trans double bonds into the 2-trans form in an array of enoyl-CoA species. PECI takes part in the beta-oxidation of unsaturated fatty acids.

Peroxisome proliferators are non-genotoxic carcinogens which are purported to exert their effect on cells through their interaction with members of the nuclear hormone receptor family termed peroxisome proliferators activated receptors (PPARs). Nuclear hormone receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate ligand. Studies indicate that PPARs are activated by peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643, as well as by some fatty acids.

PECR is the main enzyme for a projected peroxisomal chain elongation pathway and is primarily expressed in kidney and liver.

PRDX5 belongs to the peroxiredoxin family of antioxidant enzymes, which reduce hydrogen peroxide and alkyl hydroperoxides with reducing equivalents supplied through the thioredoxin system. PRDX5 has an antioxidant protective function in different tissues under normal conditions and during inflammatory processes. Peroxiredoxin-5 interacts with peroxisome receptor 1 and is involved in intracellular redox signaling. PRDX5 is involved in intracellular redox signaling. Peroxiredoxin-5 is a significant antioxidant protein of lung epithelial cells for its expression in the human lung increases during inflammation. PRDX5 expression is upregulated in osteoarthritis. PRDX5 may be significant in mitochondrial genome stability. Peroxiredoxin-5 has a protective role in human tendon cells against oxidative stress by reducing apoptosis and upholding collagen synthesis.

PRDX2 is part of the peroxiredoxin family of antioxidant enzymes, which reduce hydrogen peroxide and alkyl hydroperoxides. PRDX2 takes part as an antioxidant protective role in cells, and contributes to the antiviral activity of CD8(+) T-cells. PRDX2 has proliferative effect in cancer development or progression.
If PRDX2 protection is insufficient against peroxidases, the DNA damage results in neurological disease such as Alzheimer's or DNA damage leading to cancer.

Peroxisome proliferators are non-genotoxic carcinogens which are purported to exert their effect on cells through their interaction with members of the nuclear hormone receptor family termed peroxisome proliferators activated receptors (PPARs). Nuclear hormone receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate ligand. Studies indicate that PPARs are activated by peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643, as well as by some fatty acids.

ECH1 is a member of the hydratase/isomerase superfamily. ECH1 demonstrates high sequence similarity to enoyl-coenzyme A (CoA) hydratases of more than a few species, mostly within a conserved domain characteristic of these proteins. ECH1 contains a C-terminal peroxisomal targeting sequence, localizes to both the peroxisome and the mitochondria. peroxisomal takes part in the auxiliary step of the fatty acid beta-oxidation pathway specifically functioning to catalyze the isomerization of 3-trans, 5-cis-dienoyl-CoA to 2-trans, 4-transdienoyl-CoA.

PRDX2 is part of the peroxiredoxin family of antioxidant enzymes, which reduce hydrogen peroxide and alkyl hydroperoxides. PRDX2 takes part as an antioxidant protective role in cells, and contributes to the antiviral activity of CD8(+) T-cells. PRDX2 has proliferative effect in cancer development or progression.
If PRDX2 protection is insufficient against peroxidases, the DNA damage results in neurological disease such as Alzheimer's or DNA damage leading to cancer.

PRDX1 is part of the peroxiredoxin family of antioxidant enzymes, which reduce hydrogen peroxide and alkyl hydroperoxides. PRDX1 is an important protector of red blood cells against reactive oxygen species and in tumor prevention. PRDX1 is antioxidant protective in cells, and contributes to the antiviral activity of CD8(+) T-cells. PRDX1 has a proliferative effect and is involved in cancer development or progression. Peroxiredoxin-1 is plays a role in redox regulation of the cell. Peroxiredoxin decreases peroxides with reducing equivalents provided through the thioredoxin system but not from glutaredoxin. Peroxiredoxin is involved in eliminating peroxides generated during metabolism. Peroxiredoxin participates in the signaling cascades of growth factors and TNF-alpha by regulating the intracellular concentrations of h(2)o(2).

Peroxiredoxin 6 (PRDX6) belongs to the thiol-specific antioxidant protein family. PRDX6 is a bifunctional enzyme with 2 distinct active sites. PRDX6 is involved in redox regulation of the cell and can reduce Hydrogen peroxide and short chain organic, fatty acid, and phospholipid hydroperoxides. PRDX6 may have a role in the regulation of phospholipid turnover as well as in protection against oxidative injury. Furthermore, PRDX6 eases the oxidative stress and TGF-beta-induced abnormalities of human trabecular meshwork cells. In addition, PRDX6 is necessary for blood vessel integrity in injured skin.
At acidic pH, PRDX6 binds to reduced phospholipids, however at cytosolic pH PRDX6 binds only to phospholipids that are oxidized which is compatible with the role for PRDX6 in the repair of peroxidized cell membranes. Hydrogen peroxide-mediated hyperoxidation of PRDX6 induces cell cycle arrest at the G2/M transition via up-regulation of iPLA2 activity. Overexpression of PRDX6 is linked to oligodendroglioma.

PRDX3 is part of the peroxiredoxin family of antioxidant enzymes, that reduces hydrogen peroxide and alkyl hydroperoxides. PRDX3 is particularly located in the mitochondria and involved in the regulation of cellular redox status by serving as a primary line of defense against H2O2 produced during respiration. PRDX3 is a significant regulator of the abundance of mitochondrial H(2)O(2), which itself promotes apoptosis in cooperation with other mediators of apoptotic signaling. PRDX3 mitochondrial protein is significantly decreased in Alzheimer Disease and Down Syndrome.

Proteasome subunit beta type-2 (PSMB2) belongs to the proteasome T1B family, which is a 20S core beta subunit. The proteasome is a multicatalytic proteinase complex with a highly ordered ring-shaped 20S core structure. Proteasomes are spread throughout eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. A crucial function of a modified proteasome, the immunoproteasome, is the processing of class I MHC peptides. PSMB2 is up-regulated in ovarian cancer cell lines.

Periostin is a disulfide linked 90 kDa, 811 amino acid protein originally isolated as a osteoblast-specific factor that functions as a cell adhesion molecule for preosteoblasts and is thought to be involved in osteoblast recruitment, attachment and spreading. Additionally, periostin expression has previously been shown to be significantly increased by both transforming growth factor beta-1(TGFbeta1) and bone morphogenetic protein (BMP-2). OSF-2 has a typical signal sequence, followed by a cysteine-rich domain, a fourfold repeated domain and a C-terminal domain. The fourfold repeated domain of OSF-2 shows homology with the insect protein fasciclin
Periostin mRNA is expressed in the developing mouse embryonic and fetal heart, and that it is localized to the endocardial cushions that ultimately divide the primitive heart tube into a four-chambered heart.

Dehydrogenase/reductase SDR family member 4 (DHRS4) is a member of the short-chain dehydrogenases/reductases (SDR) family. DHRS4 reduces all trans retinal and 9-cis retinal. In addition, the DHRS4 protein can catalyze the oxidation of all trans retinol with NADP as cofactor, but with a much lower efficiency. Furthermore, DHRS4 reduces alkyl phenyl ketones and alpha dicarbonyl compounds with aromatic rings, such as pyrimidine 4 aldehyde, 3 benzoylpyridine, 4 benzoylpyridine, menadione and 4 hexanoylpyridine.

The proteasome is a multicatalytic proteinase complex with an extremely organized ring-shaped 20S core structure. The core structure consists of 4 rings of 28 non-identical subunits; 2 rings consist of 7 alpha subunits and 2 rings consist of 7 beta subunits. Proteasomes are spread all over the eukaryotic cells in large quantities and cleave peptides in an ATP/ubiquitin-dependent procedure in a non-lysosomal pathway. A vital role of a modified proteasome, the immunoproteasome, is the handling of class I MHC peptides.

Placental Growth Factor (PLGF) which is a member of the VEGF sub-family, is a growth factor active in angiogenesis, and endothelial cell growth, stimulating their proliferation and migration. PLGFmainly plays a role in trophoblast growth and differentiation and binds to receptor vegfr-1/flt1.

Phosphopantothenate-cysteine ligase (PPCS) catalyzes the first step in the biosynthesis of coenzyme A (CoA) from pantothenic acid (vitamin B5), which is a vital universal pathway in prokaryotes and eukaryotes. PPCS, being one of the last enzymes in this pathway, converts phosphopantothenate to phosphopantothenoylcysteine.

Connective Tissue Growth Factor is a part of the CCN family of proteins. The CCN family presently consists of six members in human also known as: Cyr61 (Cystein rich 61), CTGF, Nov (Nephroblastoma Overexpressed gene), WISP-1, 2 and 3 (Wnt-1 Induced Secreted Proteins). CCN proteins are matricellular proteins which are involved in the regulation of various cellular functions including: proliferation, differentiation, survival, adhesion and migration. They are expressed in derivatives of the three embryonic sheets and are implicated in the development of kidney, nervous system, muscle, bone marrow, cartilage and bone. During adulthood, they are implicated in wound healing, bone fracture repair, and pathologies such as: tumorigenesis,fibrosis and vascular ailments. Full length secreted CCN proteins can show an antiproliferative activity, whereas truncated isoforms are likely to stimulate proliferation and behave as oncogenes.
The full length protein consists of 4 modules: Module I shares partial identity with the N-terminal part of the Insulin-like Growth Factor Binding Proteins (IGFBPs).
Module II includes a stretch of 70amino acid residues – which shares sequence identity with the Von Willebrand Factor Type C repeat (VWC).
Module III contains sequences sharing identity with the Thrombospondin type 1 repeat (TSP1) (WSXCSXXCG), which is thought to be implicated in the binding of sulfated glycoconjugates and to be important for cell adhesion.
Module IV, also designated CT, is encoded by exon5. It is the leasts conserved one of the four domains at the level of nucleotide sequence, but it appears to be critical for several of the biological functions attributed to the CCN proteins.
Proteolysis of the secreted full-length CCN proteins that has been reported in the case of CCN2 and CCN3 might result in the production of CCN-derived peptides with high affinity for ligands that full-length CNN proteins bind only poorly. Amino-truncated CCN2 isoforms were biologically active whereas no specific biological activity has been attributed to the truncated CCN3. Although the molecular processes underlying the production of these secreted isoforms is presently unknown, it is important to note that proteolysis occur at the same amino acid residues in both CCN2 and CCN3. An elevated expression of CCN2 has also been detected by Northern blotting in human invasive mammary ductal carcinomas, dermatofibromas, pyogenic granuloma, endothelial cells of angiolipomas and angioleiomyomas, and in pancreatic tumors. A study performed with chondrosarcomas representative of various histological grades established that CCN2 expression was closely correlated with increasing levels of malignancy.
In agreement with CCN2 playing a role in brain tumor angiogenesis, immunocytochemistry studies indicated that both glioblastoma tumor cells and proliferating endothelial cells stained positive for CCN2. In astrocytomas, CCN2 expression was particularly elevated in high grade tumors, with a marked effect of CCN2 on cell proliferation. Downregulation of CCN2 expression in these cells was associated with a growth arrest at the G1/S transition while over-expression of CCN2 induced a two-fold increase of the number of cells in the G1 phase. Gene profiling analysis allowed to identify a set of about 50 genes whose expression might account for the proliferative activity of CCN2 in these cells.
CCN2 was seen in a higher proportion of mononuclear cells of patients with acute lymphoblastic leukemia.

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-3and GM-CSFto stimulate colony formation of hematopoietic progenitor cells in vitro and may, therefore, also modulate hematopoiesis.

PEDF is a neurotrophic protein that induces extensive neuronal differentiation in retinoblastoma cells. SerpinF1 is a potent inhibitor of angiogenesis. EPC1 doesn’t undergo the stressed to relaxed conformation transition characteristic as of the active serpins since it exhibits no serine protease inhibitory activity.
Aqueous humour level of asymmetric dimethylarginine is correlated with PEDF in humans. ADMA and PEDF levels are increased in response to inflammation in uveitis.
Lack of PEDF expression is a potent factor for the enhancement of tumor growth and angiogenesis in breast cancer.
PEDF & VEGF genes contribute to the development of diabetic retinopathy.
PEDF and VEGF structural changes in blood vessel wall play an important role in the pathophysiology of PD patients.
PEDF-overexpressing tumors exhibited reduced intratumoral angiogenesis.
SerpinF1 is a new promising approach for the treatment of osteosarcoma.
Levels of the natural ocular anti-angiogenic factor SentrinF1 (PEDF) is associated with proliferative retinopathy.
VEGF secreted by retinal pigment epithelial cells upregulates PEDF expression via VEGFR-1 in an autocrine manner.
Sentrin-F1 concentration in the aqueous humor of diabetic patients predicts who will develop progression of retinopathy.
PEDF blocks angiogenic effects of leptin through its anti-oxidative properties.