RESUMEN
Whereas prion replication involves structural rearrangement of cellular prion protein (PrP(C)), the existence of conformational epitopes remains speculative and controversial, and PrP transformation is monitored by immunoblot detection of PrP(27-30), a protease-resistant counterpart of the pathogenic scrapie form (PrP(Sc)) of PrP. We now describe the involvement of specific amino acids in conformational determinants of novel monoclonal antibodies (mAbs) raised against randomly chimeric PrP. Epitope recognition of two mAbs depended on polymorphisms controlling disease susceptibility. Detection by one, referred to as PRC5, required alanine and asparagine at discontinuous mouse PrP residues 132 and 158, which acquire proximity when residues 126-218 form a structured globular domain. The discontinuous epitope of glycosylation-dependent mAb PRC7 also mapped within this domain at residues 154 and 185. In accordance with their conformational dependence, tertiary structure perturbations compromised recognition by PRC5, PRC7, as well as previously characterized mAbs whose epitopes also reside in the globular domain, whereas conformation-independent epitopes proximal or distal to this region were refractory to such destabilizing treatments. Our studies also address the paradox of how conformational epitopes remain functional following denaturing treatments and indicate that cellular PrP and PrP(27-30) both renature to a common structure that reconstitutes the globular domain.
Asunto(s)
Epítopos/genética , Proteínas PrPC/genética , Proteínas PrPSc/genética , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales de Origen Murino/biosíntesis , Anticuerpos Monoclonales de Origen Murino/aislamiento & purificación , Bovinos , Secuencia Conservada , Ciervos , Evolución Molecular Dirigida , Mapeo Epitopo , Epítopos/química , Epítopos/inmunología , Humanos , Hibridomas , Ratones , Ratones Transgénicos , Modelos Moleculares , Datos de Secuencia Molecular , Oxidación-Reducción , Proteínas PrPC/química , Proteínas PrPC/inmunología , Proteínas PrPSc/química , Proteínas PrPSc/inmunología , Unión Proteica , Estructura Terciaria de Proteína , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/inmunología , Saimiri , Eliminación de Secuencia , OvinosRESUMEN
Leukotriene B(4)-12-hydroxydehydrogenase/15-oxo-prostaglandin 13-reductase (LTBDH/PGR) is a bifunctional enzyme capable of inactivating leukotriene B(4) (LTB(4)) and 15-oxo-prostaglandins (15-PGs). Its role in growth suppressive functions in lung cancer was studied in in vitro and in vivo systems. The LTBDH/PGR gene was expressed in lung cancer cell lines through recombinant adenovirus infection, and through a tetracycline-inducible expression system. After restoration of LTBDH/PGR expression in LTBDH/PGR-negative (H1299) or -low (A549) lung cancer cell lines, the restored enzyme induced apoptosis and growth inhibition in vitro. Ectopic expression of LTBDH/PGR caused also suppression of tumorigenicity of A549 cells in nude mice. In contrast, LTBDH/PGR over-expression in LTBDH/PGR-positive (H157) lung cancer cell line induced little apoptosis and growth inhibition. This study indicates that restoration of LTBDH/PGR expression is effective in preventing lung cancer growth in vitro and in vivo.
