title: High-density lipoprotein contribute to G0-G1/S transition in Swiss NIH/3T3 fibroblasts.
abstract: High density lipoproteins (HDLs) play a crucial role in removing excess cholesterol from peripheral tissues. Although their concentration is lower during conditions of high cell growth rate (cancer and infections), their involvement during cell proliferation is not known. To this aim, we investigated the replicative cycles in synchronised Swiss 3T3 fibroblasts in different experimental conditions: i) contact-inhibited fibroblasts re-entering cell cycle after dilution; ii) scratch-wound assay; iii) serum-deprived cells induced to re-enter G1 by FCS, HDL or PDGF. Analyses were performed during each cell cycle up to quiescence. Cholesterol synthesis increased remarkably during the replicative cycles, decreasing only after cells reached confluence. In contrast, cholesteryl ester (CE) synthesis and content were high at 24 h after dilution and then decreased steeply in the successive cycles. Flow cytometry analysis of DiO-HDL, as well as radiolabeled HDL pulse, demonstrated a significant uptake of CE-HDL in 24 h. DiI-HDL uptake, lipid droplets (LDs) and SR-BI immunostaining and expression followed the same trend. Addition of HDL or PDGF partially restore the proliferation rate and significantly increase SR-BI and pAKT expression in serum-deprived cells. In conclusion, cell transition from G0 to G1/S requires CE-HDL uptake, leading to CE-HDL/SR-BI pathway activation and CEs increase into LDs.
authors.affiliation: Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Angius
authors.affiliation: Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Spolitu
authors.affiliation: Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Uda
authors.affiliation: Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Deligia
authors.affiliation: Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Frau
authors.affiliation: Divisions of Physiology, University of Cagliari, Cagliari, Italy.
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Banni
authors.affiliation: Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Collu
authors.affiliation: Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy.
authors.forename: Simonetta
authors.initials: S
authors.lastname: Accossu
authors.affiliation: Department of Biomedical Sciences, Department of Medical Sciences "Mario Aresu", University of Cagliari, Cagliari, Italy.
authors.forename: Clelia
authors.initials: C
authors.lastname: Madeddu
authors.affiliation: Department of Biomedical Sciences, Department of Medical Sciences "Mario Aresu", University of Cagliari, Cagliari, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Serpe
authors.affiliation: Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Batetta
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D049109:Cell Proliferation / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism; D002788:Cholesterol Esters / Q000378:metabolism; D003260:Contact Inhibition / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D005434:Flow Cytometry; D005453:Fluorescence; D016193:G1 Phase; D008075:Lipoproteins, HDL / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D010766:Phosphorylation / Q000187:drug effects; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051116:Receptors, Scavenger / Q000378:metabolism; D016192:Resting Phase, Cell Cycle; D014280:Triglycerides / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D002788:Cholesterol Esters; C059714:HDL cholesteryl ester; D008075:Lipoproteins, HDL; D010982:Platelet-Derived Growth Factor; D051116:Receptors, Scavenger; D014280:Triglycerides; D002784:Cholesterol; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases