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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.

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.

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.

PPARGC1A is transcriptional coactivator for steroid receptors and nuclear receptors which increases the transcriptional activity of PPARG and thyroid hormone receptor on the uncoupling protein promoter. PPARGC1A regulates main mitochondrial genes that contribute to the program of adaptive thermogenesis and plays an important role in metabolic reprogramming in response to dietary availability through coordination of the expression of many genes participate in glucose and fatty acid metabolism. PPARGC1A induces the expression of PERM1 in the skeletal muscle and takes part in the integration of the circadian rhythms and energy metabolism.

PDRG1 is a 133 amino acid protein that localizes to the cytoplasm and belongs to the prefoldin subunit beta family. PDRG1 is expressed primarily in normal testicular tissue, it is functionally induced by ultraviolet light and is thought to have a role in chaperone-mediated protein folding, possibly having a role in cellular degradation. PDRG1 is linked to Creutzfeldt-Jakob disease, amyotrophic lateral sclerosis, spinal muscular atrophy, ring chromosome 20 epilepsy syndrome and Alagille syndrome.

The fasting-induced adipose factor (FIAF, ANGPTL4, PGAR, HFARP) was identified as an adipocytokine up-regulated by fasting, by peroxisome proliferator-activated receptor agonists, and by hypoxia. At the protein level, in human and mouse blood plasma, FIAF was found to be present both as a native protein and in a truncated form. Differentiation of mouse 3T3-L1 adipocytes was associated with the production of truncated FIAF, whereas in human white adipose tissue and SGBS adipocytes, only the native FIAF could be detected. Interestingly, the truncated FIAF was produced by human liver.
Experimental data suggest that FIAF is mainly presented in human blood plasma in a truncated form (FIAF-S2), whose level is increased by fenofibrate treatment. Levels of both truncated and native FIAF showed marked inter individual variation but were not associated with body mass index and were not influenced by prolonged semistarvation.

FIAF (fasting-induced adipose factor) a.k.a ANGPTL4 or PGAR or HFARP is an adipocytokine up-regulated by fasting, by peroxisome proliferator-activated receptor agonists, and by hypoxia. ANGPTL4 is found in human and mouse blood plasma both as a native protein and in a truncated form. In human white adipose tissue and SGBS adipocytes, only the native form of ANGPTL4 could be detected, whereas in mice the differentiation of mouse 3T3-L1 adipocytes is associated with the production of truncated ANGPTL4. However, the truncated ANGPTL4 is produced by human liver. In human blood plasma FIAF is mainly presented in a truncated form (FIAF-S2), whose levels treatment increases (as shown by experimental data). There is an inter individual variation in ANGPTL4 levels of both the truncated and the native form, however those levels were not influenced by prolonged semistarvation and are not associated with body mass index.

Inorganic pyrophosphatase (ppa) is a member of the Ppase family. PPA is an enzyme which catalyzes the conversion of one molecule of pyrophosphate to two phosphate ions. Since this is a highly exergonic reaction, it can therefore be coupled to unfavorable biochemical transformations in order to drive these transformations to completion. The role of the PPA enzyme is a critical one in the lipid metabolism (including lipid synthesis and degradation), calcium absorption and bone formation, DNA synthesis, as well as other biochemical transformations.

Inorganic pyrophosphatase (ppa) is a member of the Ppase family. PPA is an enzyme which catalyzes the conversion of one molecule of pyrophosphate to two phosphate ions. Since this is a highly exergonic reaction, it can therefore be coupled to unfavorable biochemical transformations in order to drive these transformations to completion. The role of the PPA enzyme is a critical one in the lipid metabolism (including lipid synthesis and degradation), calcium absorption and bone formation, DNA synthesis, as well as other biochemical transformations.

PMSG Hormone is a well know used hormone together with progestogen to increase ovulation just before to artificial insemination. PMSG hormone is a placental glycoprotein produced from the serum of pregnant mares. PMSG comprises of an alfa subunit and a beta subunit. PMSG hormone is secreted from endometrial cups within the pregnant mare uterus aging from 40 to 130 days into their maturation, and once extracted, it can been used to promote artificially estrus in female animals. These assemblies produce PMSG hormone to induce mare's ovarian and repsouctive structures. PMSG can induce the growth of follicles by ovaries and results in ovulatation. PMSG hormone has an about a 4 day half-life of bioactivity in species other than horses. The extended biological activity can cause ovarian stimulation and ovulation. However, PMSG use alone often causes cystic ovarian disease because of the unrestrained ovarian stimulation and due to the sugar molecules which decrease clearance of the hormone. PMSG is more likely to be used than other pituitary hormones due to the extended circulatory half-life. PMSG solely exhibits luteinizing hormone like activity, however in other animal classes it has FSH & LH like activity.

Platelet-derived growth factor receptor beta (PDGFRB), belongs to the class III subfamily of receptor tyrosine kinases (RTK) which also consist of the receptors for Flt3-ligand, SCF and M-CSF. PDGFRB takes a vital part in blood vessel development by promoting growth, migration as well as recruitment of pericytes and smooth muscle cells to endothelial cells. PDGFRB helps in rearrangement of the actin cytoskeleton in addition the formation of membrane ruffles. PDGFRB phosphorylates, NCK1, PIK3R1, PTPN11, CBL, SHC1, RASA1/GAP and PLCG1.

Prostaglandin Reductase 2 (PTGR2) is a member of the medium-chain dehydrogenase/reductase superfamily. PTGR2 is an enzyme involved in the metabolism of prostaglandins. PTGR2 catalyzes an NADPH-dependent reduction of the conjugated alpha, beta-unsaturated double bond of 15-keto-PGE(2), which is a fundamental step in terminal inactivation of prostaglandins and suppression of PPARgamma-mediated adipocyte differentiation. PTGR2 may also be involved in controlling activation of the peroxisome proliferator-activated receptor.

Small nuclear ribonucleoprotein polypeptide G (SNRPG) is a member of the snRNP Sm proteins family. There are at least 7 isoforms, B/B, E, F, G, D1, D2, and D3. This class of common proteins has a vital role in the biogenesis of the snRNPs. The human Sm G genes are mapped to chromosomes 2. Furthermore, these proteins represent the major targets for the supposed anti-Sm auto-antibodies which are diagnostic for SLE (systemic lupus erythematosus). One class of these autoantibodies reacts specifically with native Sm E-F-G complexes.

Acyl-CoA synthetase family member 2, also known as ACSF2 is a member of the ATP-dependent AMP-binding enzyme family. Acyl-CoA synthetases are a family of enzymes which catalyze the thioesterification of fatty acids with coenzymeA to form activated intermediates, which play a basic part in lipid metabolism as well as homeostasis of lipid-related processes. ACSF2 is required for the complex of lipid synthesis, energy production via beta-oxidation, protein acylation and fatty-acid dependent transcriptional regulation. Moreover, ACSF2 is required for fatty acid import into cells by the process of vectorial acylation.

PDGFRa is a cell surface tyrosine kinase receptor for PDGF family members. PDGFRa binds to both A and B subunits of PDGF. It is known that PDGFRa is vital for kidney development since mice heterozygous for the receptor display defective kidney phenotypes.

Prostaglandin Reductase 1 (PTGR1) is a member of the NADP-dependent oxidoreductase L4BD family. PTGR1 catalyzes the conversion of leukotriene B4 into its biologically less active metabolite, 12-oxo-leukotriene B4, thus being a primary step of metabolic inactivation of leukotriene B4. PTGR1 is highly expressed in the kidney, liver, and intestine but not in leukocytes.

Pregnancy Specific Beta-1-Glycoprotein 1 (PSG1) is a member of a subgroup of transcription factors which are phosphorylated upon binding to promoter sequences. PSGs belong to the carcinoembryonic antigen (CEA) family and function as early biochemical markers of syncytiotrophoblast formation. Furthermore, PSG1 is assumed to mediate placental vascular morphogenesis by enhancing VEGF-A production and endothelial tube formation. PSG1 is a major product of the syncytiotrophoblast, reaching concentrations of 100- 290 mg/l at term in the serum of pregnant women.

The PARK7 is a ubiquitously expressed protein involved in various cellular processes including spermatogenesis and fertilization, cancer, RNA-binding, androgen-receptor signaling and oxidative stress. Mutations in the PARK7 are the cause of autosomal recessive early-onset Parkinson’s disease 7 (Park7).

PDGF-BB 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 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 7, 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.

PA2G4 belongs to the peptidase M24C family and functions as an RNA-binding protein involved in cellular proliferation and differentiation processes. PA2G4 is a component of pre-ribosomal ribonucleoprotein complexes, participating in ribosome assembly and regulating the later steps of rRNA processing. Also, PA2G4 interacts with ErbB-3 and may function as a modulator of the ErbB-3 mediated signal transduction pathway by regulating the effects of Neuregulin-1. Furthermore, PA2G4 is a transcriptional co-repressor of androgen receptor-regulated genes and other cell cycle regulatory genes through its interactions with histone deacetylases. PA2G4 is implicated in growth inhibition and the induction of differentiation of human cancer cells. In addition, PA2G4 mediates cap-independent translation of specific viral IRESs (internal ribosomal entry site). PA2G4 associates with 28S, 18S and 5.8S mature rRNAs, several rRNA precursors and probably U3 small nucleolar RNA.

Glucagon receptor is part of the glucagon receptor family which also contains GLP-1, GLP-2, GHRH and GIP receptors. GCGR regulates blood glucose levels and is mainly expressed in the pancreas, liver and kidneys. Mutations in GCGR are a cause of non-insulin-dependent diabetes mellitus.

Acyl-CoA synthetase family member 2, also known as ACSF2 is a member of the ATP-dependent AMP-binding enzyme family. Acyl-CoA synthetases are a family of enzymes which catalyze the thioesterification of fatty acids with coenzymeA to form activated intermediates, which play a basic part in lipid metabolism as well as homeostasis of lipid-related processes. ACSF2 is required for the complex of lipid synthesis, energy production via beta-oxidation, protein acylation and fatty-acid dependent transcriptional regulation. Moreover, ACSF2 is required for fatty acid import into cells by the process of vectorial acylation.

Melanoregulin (MREG) takes part in membrane fusion and in regulating the biogenesis of disk membranes of photoreceptor rods. MREG is expressed in photoreceptor cells as two isoforms as a result of alternative splicing. MREG interacts with Peripherin-2, a photoreceptor specific tetraspanin protein which is required to preserve normal cell structure during the renewal process of membrane fusion. Moreover, MREG plays a part in the incorporation of pigments into hair.

Signal-Regulatory Protein Gamma (SIRPG) belongs to the signal-regulatory protein (SIRP) family whose members are receptor-type transmembrane glycoproteins which negatively regulate the receptor tyrosine kinase-coupled signaling processes. SIRPG is also a part of the immunoglobulin superfamily.