The distribution of melanopsin (OPN4) protein in the human brain.

Until now, melanopsin (OPN4) - a specialized photopigment being responsive especially to blue light wavelengths - has not been found in the human brain at protein level outside the retina. More specifically, OPN4 has only been found in about 2% of retinal ganglion cells (i.e.

Role of AMACR (α-methylacyl-CoA racemase) and MFE-1 (peroxisomal multifunctional enzyme-1) in bile acid synthesis in mice.

Cholesterol is catabolized to bile acids by peroxisomal β-oxidation in which the side chain of C27-bile acid intermediates is shortened by three carbon atoms to form mature C24-bile acids. Knockout mouse models deficient in AMACR (α-methylacyl-CoA racemase) or MFE-2 (peroxisomal multifunctional enzyme type 2), in which this β-oxidation pathway is prevented, display a residual C24-bile acid pool which, although greatly reduced, implies the existence of alternative pathways of bile acid synthesis. One alternative pathway could involve Mfe-1 (peroxisomal multifunctional enzyme type 1) either with or without Amacr.

Peroxisomal membrane channel Pxmp2 in the mammary fat pad is essential for stromal lipid homeostasis and for development of mammary gland epithelium in mice.

To understand the functional role of the peroxisomal membrane channel Pxmp2, mice with a targeted disruption of the Pxmp2 gene were generated. These mice were viable, grew and bred normally. However, Pxmp2(-/-) female mice were unable to nurse their pups.

Lung cancer-associated myofibroblasts reveal distinctive ultrastructure and function.

Background: Cancer-associated stromal cells interact with carcinoma cells and thus participate in tumor growth. Our aim was to characterize the ultrastructure and contractile properties of stromal cells in collagen gel cultured from lung cancer of various histological types and from tumor-free lung.

Methods: Cells cultured from lung cancer (13 adenocarcinomas, six squamous cell carcinomas, one adenosquamous carcinoma, and one pleomorphic carcinoma) and tumor-free lung were analyzed by transmission electron microscopy and three-dimensional collagen gel contraction assays.

Transmembrane prostatic acid phosphatase (TMPAP) interacts with snapin and deficient mice develop prostate adenocarcinoma.

The molecular mechanisms underlying prostate carcinogenesis are poorly understood. Prostatic acid phosphatase (PAP), a prostatic epithelial secretion marker, has been linked to prostate cancer since the 1930's. However, the contribution of PAP to the disease remains controversial.

Myofibroblast expression in airways and alveoli is affected by smoking and COPD.

Background: Chronic obstructive pulmonary disease (COPD) is characterized by structural changes in alveoli and airways. Our aim was to analyse the numbers of alpha-smooth muscle actin (α-SMA) positive cells, as a marker of myofibroblasts, in different lung compartments in non-smokers and smokers with normal lung function or COPD.

Methods: α-SMA, tenascin-C (Tn-C) and EDA-fibronectin in alveolar level and airways were assayed by immunohistochemistry and quantified by image analysis.

Myofibroblasts in interstitial lung diseases show diverse electron microscopic and invasive features.

The characteristic features of myofibroblasts in various lung disorders are poorly understood. We have evaluated the ultrastructure and invasive capacities of myofibroblasts cultured from small volumes of diagnostic bronchoalveolar lavage (BAL) fluid samples from patients with different types of lung diseases. Cells were cultured from samples of BAL fluid collected from 51 patients that had undergone bronchoscopy and BAL for diagnostic purposes.

Myocardial overexpression of Mecr, a gene of mitochondrial FAS II leads to cardiac dysfunction in mouse.

It has been recently recognized that mammalian mitochondria contain most, if not all, of the components of fatty acid synthesis type II (FAS II). Among the components identified is 2-enoyl thioester reductase/mitochondrial enoyl-CoA reductase (Etr1/Mecr), which catalyzes the NADPH-dependent reduction of trans-2-enoyl thioesters, generating saturated acyl-groups. Although the FAS type II pathway is highly conserved, its physiological role in fatty acid synthesis, which apparently occurs simultaneously with breakdown of fatty acids in the same subcellular compartment in mammals, has remained an enigma.

Pxmp2 is a channel-forming protein in Mammalian peroxisomal membrane.

Background: Peroxisomal metabolic machinery requires a continuous flow of organic and inorganic solutes across peroxisomal membrane. Concerning small solutes, the molecular nature of their traffic has remained an enigma.

Methods/principal Findings: In this study, we show that disruption in mice of the Pxmp2 gene encoding Pxmp2, which belongs to a family of integral membrane proteins with unknown function, leads to partial restriction of peroxisomal membrane permeability to solutes in vitro and in vivo.

Channel-forming activities of peroxisomal membrane proteins from the yeast Saccharomyces cerevisiae.

Highly-purified peroxisomes from the yeast Saccharomyces cerevisiae grown on oleic acid were investigated for the presence of channel (pore)-forming proteins in the membrane of these organelles. Solubilized membrane proteins were reconstituted in planar lipid bilayers and their pore-forming activity was studied by means of multiple-channel monitoring or single-channel analysis. Two abundant pore-forming activities were detected with an average conductance of 0.

UK114, a YjgF/Yer057p/UK114 family protein highly conserved from bacteria to mammals, is localized in rat liver peroxisomes.

Mammalian UK114 belongs to a highly conserved family of proteins with unknown functions. Although it is believed that UK114 is a cytosolic or mitochondrial protein there is no detailed study of its intracellular localization. Using analytical subcellular fractionation, electron microscopic colloidal gold technique, and two-dimensional gel electrophoresis of peroxisomal matrix proteins combined with mass spectrometric analysis we show here that a large portion of UK114 is present in rat liver peroxisomes.

Localization of a portion of the liver isoform of fatty-acid-binding protein (L-FABP) to peroxisomes.

The liver isoform of fatty-acid-binding protein (L-FABP) facilitates the cellular uptake, transport and metabolism of fatty acids and is also involved in the regulation of gene expressions and cell differentiation. Consistent with these functions, L-FABP is predominantly present in the cytoplasm and to a lesser extent in the nucleus; however, a significant portion of this protein has also been detected in fractions containing different organelles. More recent observations, notably on L-FABP-deficient mice, indicated a possible direct involvement of L-FABP in the peroxisomal oxidation of long-chain fatty acids.

The rat liver peroxisomal membrane forms a permeability barrier for cofactors but not for small metabolites in vitro.

The functional role of the peroxisomal membrane as a permeability barrier to metabolites has been a matter of controversy for more than four decades. The initial conception, claiming free permeability of the membrane to small solute molecules, has recently been challenged by several observations suggesting that the peroxisomal membrane forms a closed compartment. We have characterized in vitro the permeability of rat liver peroxisomal membrane.

Htd2p/Yhr067p is a yeast 3-hydroxyacyl-ACP dehydratase essential for mitochondrial function and morphology.

Among the recently recognized aspects of mitochondrial functions, in yeast as well as humans, is their ability to synthesize fatty acids in a malonyl-CoA dependent manner. We describe here the identification of the 3-hydroxyacyl-ACP dehydratase involved in mitochondrial fatty acid synthesis. A colony-colour-sectoring screen was applied in Saccharomyces cerevisiae in a search for mutants that, when grown on a non-fermentable carbon source, were unable to lose a plasmid that carried a chimeric construct coding for mitochondrially localized bacterial analogue.

The behavior of peroxisomes in vitro: mammalian peroxisomes are osmotically sensitive particles.

It has been known for a long time that mammalian peroxisomes are extremely fragile in vitro. Changes in the morphological appearance and leakage of proteins from purified particles demonstrate that peroxisomes are damaged during isolation. However, some properties of purified peroxisomes, e.

Cell-specific regulation of gamma-glutamylcysteine synthetase in human interstitial lung diseases.

The pathogenesis of interstitial lung diseases (ILDs) is known to be associated with reactive oxygen and nitrogen metabolites and increased oxidant stress. One of the major antioxidants in human lung is glutathione (GSH) and enzymes linked to its synthesis. The rate-limiting enzyme of GSH synthesis is gamma-glutamylcysteine synthetase (gamma-GCS) containing catalytically active heavy (gamma-GCSh) and regulatory light (gamma-GCSl) subunits.

A mouse model for alpha-methylacyl-CoA racemase deficiency: adjustment of bile acid synthesis and intolerance to dietary methyl-branched lipids.

alpha-Methylacyl-CoA racemase (Amacr) deficiency in humans leads to sensory motor neuronal and liver abnormalities. The disorder is recessively inherited and caused by mutations in the AMACR gene, which encodes Amacr, an enzyme presumed to be essential for bile acid synthesis and to participate in the degradation of methyl-branched fatty acids. To generate a model to study the pathophysiology in Amacr deficiency we inactivated the mouse Amacr gene.

Characterization of 2-enoyl thioester reductase from mammals. An ortholog of YBR026p/MRF1'p of the yeast mitochondrial fatty acid synthesis type II.

A data base search with YBR026c/MRF1', which encodes trans-2-enoyl thioester reductase of the intramitochondrial fatty acid synthesis (FAS) type II in yeast (Torkko, J. M., Koivuranta, K.

Structure-function analysis of enoyl thioester reductase involved in mitochondrial maintenance.

Candida tropicalis enoyl thioester reductase Etr1p and the Saccharomyces cerevisiae homologue Mrf1p catalyse the NADPH-dependent reduction of trans-2-enoyl thioesters in mitochondrial fatty acid synthesis (FAS). Unlike prokaryotic enoyl thioester reductases (ETRs), which belong to the short-chain dehydrogenases/reductases (SDR), Etr1p and Mrf1p represent structurally distinguishable ETRs that belong to the medium-chain dehydrogenases/reductases (MDR) superfamily, indicating independent origin of two separate classes of ETRs. The crystal structures of Etr1p, the Etr1p-NADPH complex and the Etr1Y79Np mutant were refined to 1.