title: Beta-2-glycoprotein I is growth regulated and plays a role as survival factor for hepatocytes.
abstract: Beta-2-glycoprotein I (beta(2)GPI) is mainly produced by the liver and is found in plasma partially associated to lipoproteins. Although various properties have been attributed to this protein, its physiological role remains still unclear. We investigated its expression in cultured liver cells and in regenerating liver. Expression studies in HepG2 cells demonstrate that beta(2)GPI mRNA is regulated in a cell cycle-dependent manner, with very low expression in low cycling conditions and increasing levels in proliferating cells. p21 WAF-dependent growth arrest, induced by butyrate treatment, down-regulate beta(2)GPI mRNA levels. Immunolocalization in normal rat liver shows a non-homogeneous pattern, being mainly present in the centrolobular area; post-hepatectomy regenerating rat liver is uniformly immunostained and mitotic elements show the highest protein expression. Albumin gene expression, studies as control liver specific product, was not affected by sodium butyrate induced growth arrest. As previously reported for endothelial cells, beta(2)GPI behaves as survival factor for HepG2 cells: when increasing amounts of the protein (10-50 microg) have been added to serum deficient cultured liver cells a progressive reduced cell loss was observed. In conclusion, the present data demonstrate that beta(2)GPI gene expression is strictly related to the proliferative status of hepatic cells and that this protein could play a role in maintaining liver cells vitality when exposed to different stress factors such as regeneration after partial hepatectomy or growth factors depletion.
authors.affiliation: Department of Internal Medicine, University of Palermo, Via del Vespro 141, 90127 Palermo, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Averna
authors.forename: Gianluca
authors.initials: G
authors.lastname: Paravizzini
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Marino
authors.forename: Giovanni
authors.initials: G
authors.lastname: Emmanuele
authors.forename: Angelo Baldassare
authors.initials: AB
authors.lastname: Cefalù
authors.forename: Gaetano
authors.initials: G
authors.lastname: Magro
authors.forename: Giovanni
authors.initials: G
authors.lastname: Bartoloni
authors.forename: Maria
authors.initials: M
authors.lastname: Ragusa
authors.forename: Davide
authors.initials: D
authors.lastname: Noto
authors.forename: Carlo Maria
authors.initials: CM
authors.lastname: Barbagallo
authors.forename: Daniela
authors.initials: D
authors.lastname: Callari
authors.forename: Maria Clorinda
authors.initials: MC
authors.lastname: Mazzarino
authors.forename: Alberto
authors.initials: A
authors.lastname: Notarbartolo
authors.forename: Salvatore
authors.initials: S
authors.lastname: Travali
mesh_terms: D000418:Albumins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002087:Butyrates / Q000494:pharmacology; D018929:Cell Culture Techniques; D002470:Cell Survival; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D022781:Hepatocytes / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008099:Liver / Q000648:ultrastructure; D008115:Liver Regeneration; D051381:Rats; D017208:Rats, Wistar; D053482:beta 2-Glycoprotein I
chemical_list: D000418:Albumins; D002087:Butyrates; D006023:Glycoproteins; D053482:beta 2-Glycoprotein I