RESUMO
Calcium (Ca2+) release from the endoplasmic reticulum plays an important role in many cell-fate defining cellular processes. Traditionally, this Ca2+ release was associated with the ER Ca2+ release channels, inositol 1,4,5triphosphate receptor (IP3R) and ryanodine receptor (RyR). Lately, however, other calcium conductances have been found to be intracellularly localized and to participate in cell fate regulation. Nonetheless, molecular identity and functional properties of the ER Ca2+ release mechanisms associated with multiple diseases, e.g. prostate cancer, remain unknown. Here we identify a new family of transient receptor potential melastatine 8 (TRPM8) channel isoforms as functional ER Ca2+ release channels expressed in mitochondria-associated ER membranes (MAMs). These TRPM8 isoforms exhibit an unconventional structure with 4 transmembrane domains (TMs) instead of 6 TMs characteristic of the TRP channel archetype. We show that these 4TM-TRPM8 isoforms form functional channels in the ER and participate in regulation of the steady-state Ca2+ concentration ([Ca2+]) in mitochondria and the ER. Thus, our study identifies 4TM-TRPM8 isoforms as ER Ca2+ release mechanism distinct from classical Ca2+ release channels.
Assuntos
Cálcio/metabolismo , Retículo Endoplasmático/metabolismo , Mitocôndrias/metabolismo , Neoplasias da Próstata/metabolismo , Canais de Cátion TRPM/genética , Canais de Cátion TRPM/metabolismo , Idoso , Processamento Alternativo , Linhagem Celular Tumoral , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Próstata/citologia , Próstata/metabolismo , Neoplasias da Próstata/genética , Domínios Proteicos , Canais de Cátion TRPM/químicaRESUMO
Prion diseases are fatal neurodegenerative and infectious disorders for which effective pharmacological tools are not yet available. This unmet challenge and the recently proposed interplay between prion diseases and Alzheimer's have led to a more urgent demand for new antiprion agents. Herein, we report the identification of a novel bifunctional diketopiperazine (DKP) derivative 1 d, which exhibits activity in the low micromolar range against prion replication in ScGT1 cells, while showing low cytotoxicity. Supported by properly addressed molecular modeling studies, we hypothesized that a planar conformation is the major determinant for activity in this class of compounds. Moreover, studies aimed at assessing the mechanism-of-action at the molecular level showed that 1 d might interact directly with recombinant prion protein (recPrP) to prevent its conversion to the pathogenic misfolded prion protein (PrP(Sc))-like form. This investigation suggests that DKP based antiprion compounds can serve as a promising lead scaffold in developing new drugs to combat prion diseases.