ABSTRACT
Neuropeptide Y (NPY) is abundantly expressed in the nervous system and acts on target cells through NPY receptors. The human adrenal cortex and adrenal tumors express NPY receptor subtype Y1, but its function is unknown. We studied Y1-mediated signaling, steroidogenesis and cell proliferation in human adrenal NCI-H295R cells. Radioactive ligand binding studies showed that H295R cells express Y1 receptor specifically. NPY treatment of H295R cells stimulated the MEK/ERK1/2 pathway, confirming that H295R cells express functional Y1 receptors. Studies of the effect of NPY and related peptide PYY on adrenal steroidogenesis revealed a decrease in 11-deoxycortisol production. RIA measurements of cortisol from cell culture medium confirmed this finding. Co-treatment with the Y1 antagonist BIBP2336 reversed the inhibitory effect of NPY on cortisol production proving specificity of this effect. At mRNA level, NPY decreased HSD3B2 and CYP21A2 expression. However NPY revealed no effect on cell proliferation. Our data show that NPY can directly regulate human adrenal cortisol production.
Subject(s)
Adrenal Glands/cytology , Neuropeptide Y/metabolism , Receptors, Neuropeptide Y/metabolism , Adrenal Glands/drug effects , Adrenal Glands/metabolism , Aldosterone/biosynthesis , Cell Line , Cell Proliferation/drug effects , Extracellular Signal-Regulated MAP Kinases/metabolism , Humans , Hydrocortisone/biosynthesis , Hydroxysteroid Dehydrogenases/genetics , Hydroxysteroid Dehydrogenases/metabolism , MAP Kinase Kinase Kinases/metabolism , Neuropeptide Y/genetics , Neuropeptide Y/pharmacology , Peptide YY/metabolism , Radioimmunoassay , Receptors, Neuropeptide Y/genetics , Signal Transduction/physiology , Testosterone/biosynthesisABSTRACT
The function of vitamin E has been attributed to its capacity to protect the organism against the attack of free radicals by acting as a lipid based radical chain breaking molecule. More recently, alternative non-antioxidant functions of vitamin E have been proposed and in particular that of a "gene regulator". Effects of vitamin E have been observed at the level of mRNA or protein and could be consequent to regulation of gene transcription, mRNA stability, protein translation, protein stability and post-translational events. Given the high priority functions assigned to vitamin E, it can be speculated that it would be inefficient to consume it as a radical scavenger. Rather, it would be important to protect vitamin E through a network of cellular antioxidant defences, similarly to what occurs with proteins, nucleic acids and lipids.
Subject(s)
Antioxidants/metabolism , alpha-Tocopherol/metabolism , Animal Diseases/prevention & control , Animals , Arteriosclerosis/prevention & control , Ataxia/prevention & control , Cardiovascular Diseases/epidemiology , Cardiovascular Diseases/prevention & control , Free Radicals/metabolism , Gene Expression Regulation , Humans , Male , Prostatic Neoplasms/prevention & control , Protein Processing, Post-Translational , Proteins/metabolism , RNA, Messenger/metabolism , Signal Transduction , Transcription, Genetic , gamma-Tocopherol/metabolismABSTRACT
The effect of the expression of murine Bax protein on growth and vitality was examined in Saccharomyces cerevisiae and compared with the effect of Bax in mutant cells lacking functional mitochondria. The cytotoxic effect of Bax on yeast does not require functional oxidative phosphorylation, respiration, or mitochondrial proteins (ADP/ATP carriers) implicated in the formation of the permeability transition pore in mammalian mitochondria. In the wild type S. cerevisiae the expression of Bax does not result in a severe effect on mitochondrial membrane potential and respiration. On the basis of Bax induced differences in the fluorescence of green fluorescent protein fused to mitochondrial proteins, it is proposed that Bax may interfere with one essential cellular process in yeast: the mitochondrial protein import pathway that is specific for the proteins of the mitochondrial carrier family.
