[Molecular bases of diseases caused by mutations in genes encoding subunits of ATP synthase].

ATP synthase is the last enzyme of the OXPHOS system synthesizing ATP. Mutations in either mitochondrial or nuclear genes encoding subunits of this enzyme (17 polypeptides) cause neurodegenerative diseases. The ATP synthase subunits 8 (ATP8, alias A6L) and a (ATP6) are encoded by the MT-ATP8 and MT-ATP6 mitochondrial genes, respectively.

Friends, science and freedom-Can one ask for more.

The author describes her life in science, starting from 1945 in post II world war Warsaw to an enthusiastic and devoted member of the international yeast community, recalling her collaboration with laboratories from US through Australia to France and Germany where she met great scientists and great friends.

Hem12, an enzyme of heme biosynthesis pathway, is monoubiquitinated by Rsp5 ubiquitin ligase in yeast cells.

Heme biosynthesis pathway is conserved in yeast and humans and hem12 yeast mutants mimic porphyria cutanea tarda (PCT), a hereditary human disease caused by mutations in the UROD gene. Even though mutations in other genes also affect UROD activity and predispose to sporadic PCT, the regulation of UROD is unknown. Here, we used yeast as a model to study regulation of Hem12 by ubiquitination and involvement of Rsp5 ubiquitin ligase in this process.

Yeast as a system for modeling mitochondrial disease mechanisms and discovering therapies.

Mitochondrial diseases are severe and largely untreatable. Owing to the many essential processes carried out by mitochondria and the complex cellular systems that support these processes, these diseases are diverse, pleiotropic, and challenging to study. Much of our current understanding of mitochondrial function and dysfunction comes from studies in the baker's yeast Saccharomyces cerevisiae.

The portal theory supported by venous drainage-selective fat transplantation.

Objective: The "portal hypothesis" proposes that the liver is directly exposed to free fatty acids and cytokines increasingly released from visceral fat tissue into the portal vein of obese subjects, thus rendering visceral fat accumulation particularly hazardous for the development of hepatic insulin resistance and type 2 diabetes. In the present study, we used a fat transplantation paradigm to (artificially) increase intra-abdominal fat mass to test the hypothesis that venous drainage of fat tissue determines its impact on glucose homeostasis.

Research Design And Methods: Epididymal fat pads of C57Bl6/J donor mice were transplanted into littermates, either to the parietal peritoneum (caval/systemic venous drainage) or, by using a novel approach, to the mesenterium, which confers portal venous drainage.

Regulation of sporulation in the yeast Saccharomyces cerevisiae.

Sporulation of the budding yeast Saccharomyces cerevisiae — equivalent to gametogenesis in higher organisms, is a complex differentiation program induced by starvation of cells for nitrogen and carbon. Such environmental conditions activate coordinated, sequential changes in gene expression leading to production of haploid, stress-resistant spores. Sporulation comprises two rounds of meiosis coupled with spore morphogenesis and is tightly controlled to ensure viable progeny.

Mutants of the Saccharomyces cerevisiae VPS genes CCZ1 and YPT7 are blocked in different stages of sporulation.

The CCZ1 gene is a member of the class B VPS (vacuolar protein sorting) genes and it is engaged in the last stage of delivery of multiple kinds of cargo to the yeast vacuole. In the process of fusion of the multivesicular body (MVB) with the vacuole, Ccz1p forms a complex with Ypt7p. Both genes are non-essential for vegetative growth, but their deletions cause a complete block in spore formation.

Toll-like receptor 2-deficient mice are protected from insulin resistance and beta cell dysfunction induced by a high-fat diet.

Aims/hypothesis: Inflammation contributes to both insulin resistance and pancreatic beta cell failure in human type 2 diabetes. Toll-like receptors (TLRs) are highly conserved pattern recognition receptors that coordinate the innate inflammatory response to numerous substances, including NEFAs. Here we investigated a potential contribution of TLR2 to the metabolic dysregulation induced by high-fat diet (HFD) feeding in mice.

Deletion of Fas in adipocytes relieves adipose tissue inflammation and hepatic manifestations of obesity in mice.

Adipose tissue inflammation is linked to the pathogenesis of insulin resistance. In addition to exerting death-promoting effects, the death receptor Fas (also known as CD95) can activate inflammatory pathways in several cell lines and tissues, although little is known about the metabolic consequence of Fas activation in adipose tissue. We therefore sought to investigate the contribution of Fas in adipocytes to obesity-associated metabolic dysregulation.

Mutations in the Saccharomyces cerevisiae vacuolar fusion proteins Ccz1, Mon1 and Ypt7 cause defects in cell cycle progression in a num1Delta background.

The proteins Ccz1 and Mon1 are known to function together with the Rab-GTPase Ypt7 in membrane fusion reactions at the yeast vacuole. In a genome-wide analysis they have also been found to interact genetically with the nuclear-migration protein Num1. In this study we analyze these synthetic effects and we show that the mutants ccz1Delta num1Delta, mon1Delta num1Delta and ypt7Delta num1Delta exhibit severe defects in cell cycle progression.

The Saccharomyces cerevisiae protein Ccz1p interacts with components of the endosomal fusion machinery.

The yeast protein Ccz1p is necessary for vacuolar protein trafficking and biogenesis. In a complex with Mon1p, it mediates fusion of transport intermediates with the vacuole membrane by activating the small GTPase Ypt7p. Additionally, genetic data suggest a role of Ccz1p in earlier transport steps, in the Golgi.

Functional expression of human HMG-CoA reductase in Saccharomyces cerevisiae: a system to analyse normal and mutated versions of the enzyme in the context of statin treatment.

Aims: Statins - inhibitors of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase - are known to reduce blood cholesterol levels. In this paper, we present a Saccharomyces cerevisiae expression system, which enables quick evaluation of the sensitivity of the wild-type and/or mutant forms of human HMG-CoA reductase towards statins or other drugs.

Methods And Results: We analysed the sequence of the HMG-CoA reductase gene in DNA extracted from blood samples of 16 patients with cardiovascular disorders.

New in vitro colonic fermentation model for Salmonella infection in the child gut.

In this study, a new in vitro continuous colonic fermentation model of Salmonella infection with immobilized child fecal microbiota and Salmonella serovar Typhimurium was developed for the proximal colon. This model was then used to test the effects of two amoxicillin concentrations (90 and 180 mg day(-1)) on the microbial composition and metabolism of the gut microbiota and on Salmonella serovar Typhimurium during a 43-day fermentation. Addition of gel beads (2%, v/v) colonized with Salmonella serovar Typhimurium in the reactor resulted in a high and stable Salmonella concentration (log 7.

Basal lipolysis, not the degree of insulin resistance, differentiates large from small isolated adipocytes in high-fat fed mice.

Aims/hypothesis: Adipocytes in obesity are characterised by increased cell size and insulin resistance compared with adipocytes isolated from lean patients. However, it is not clear at present whether hypertrophy actually does drive adipocyte insulin resistance. Thus, the aim of the present study was to metabolically characterise small and large adipocytes isolated from epididymal fat pads of mice fed a high-fat diet (HFD).

A yeast model of the neurogenic ataxia retinitis pigmentosa (NARP) T8993G mutation in the mitochondrial ATP synthase-6 gene.

NARP (neuropathy, ataxia, and retinitis pigmentosa) and MILS (maternally inherited Leigh syndrome) are mitochondrial disorders associated with point mutations of the mitochondrial DNA (mtDNA) in the gene encoding the Atp6p subunit of the ATP synthase. The most common and studied of these mutations is T8993G converting the highly conserved leucine 156 into arginine. We have introduced this mutation at the corresponding position (183) of yeast Saccharomyces cerevisiae mitochondrially encoded Atp6p.

The yeast protein sorting pathway as an experimental model for lysosomal trafficking.

Lysosomes are conserved organelles that are present in all eukaryotic cells. They are part of a complicated network of intracellular trafficking routes - the lysosomal transport system. Lysosomes are necessary for the maintenance of cellular homeostasis and for many specialized functions, including the activity of many components of the mammalian immune system.

Yeast cells lacking the mitochondrial gene encoding the ATP synthase subunit 6 exhibit a selective loss of complex IV and unusual mitochondrial morphology.

Atp6p is an essential subunit of the ATP synthase proton translocating domain, which is encoded by the mitochondrial DNA (mtDNA) in yeast. We have replaced the coding sequence of Atp6p gene with the non-respiratory genetic marker ARG8m. Due to the presence of ARG8m, accumulation of rho-/rho0 petites issued from large deletions in mtDNA could be restricted to 20-30% by growing the atp6 mutant in media lacking arginine.

Fcf1p and Fcf2p are novel nucleolar Saccharomyces cerevisiae proteins involved in pre-rRNA processing.

The uncharacterized Saccharomyces cerevisiae proteins Fcf1 and Fcf2, encoded by the ORFs YDR339c and YLR051c, respectively, were identified in a tandem affinity purification experiment of the known 40S factor Faf1p. Most of the proteins associated with TAP-Faf1p are trans-acting factors involved in pre-rRNA processing and 40S subunit biogenesis, in agreement with the previously observed role of Faf1p in 18S rRNA synthesis. Fcf1p and Fcf2p are both essential and localize to the nucleolus.

Interplay between the cis-prenyltransferases and polyprenol reductase in the yeast Saccharomyces cerevisiae.

Dolichol formation is examined in three Saccharomyces cerevisiae strains with mutations in the ERG20 gene encoding farnesyl diphosphate synthase (mevalonic acid pathway) and/or the ERG9 gene encoding squalene synthase (sterol synthesis pathway) differing in the amount and chain length of the polyisoprenoids synthesized. Our results suggest that the activities of two yeast cis-prenyltransferases Rer2p and Srt1p and polyprenol reductase are not co-regulated and that reductase may be the rate-limiting enzyme in dolichol synthesis if the amount of polyisoprenoids synthesized exceeds a certain level. We demonstrate that reductase preferentially acts on typical polyprenols with 13-18 isoprene residues but can reduce much longer polyprenols with even 32 isoprene residues.

Pan1p, an actin cytoskeleton-associated protein, is required for growth of yeast on oleate medium.

Pan1p is a yeast actin cytoskeleton-associated protein localized in actin patches. It activates the Arp2/3 complex, which is necessary for actin polymerization and endocytosis. We isolated the pan1-11 yeast mutant unable to grow on oleate as a sole carbon source and, therefore, exhibiting the Oleate- phenotype.

The CHiPS Domain--ancient traces for the Hermansky-Pudlak syndrome.

Hermansky-Pudlak syndrome (HPS) is a rare disorder caused by malfunctions of lysosomes and specialized lysosome-related organelles, resulting primarily in oculocutaneous albinism and bleeding diathesis. The majority of the HPS genes have been described as novel, but herein we report the identification of a conserved protein family which includes human HPS4, as well as distant homologs for other HPS genes. Our results suggest that the cellular machinery involved in the HPS syndrome is ancient.

The bromodomain-containing protein Bdf1p acts as a phenotypic and transcriptional multicopy suppressor of YAF9 deletion in yeast.

It was observed previously that the deletion of the open reading frame YNL107w (YAF9) was highly pleiotropic in yeast and caused defective growth phenotypes in the presence of several unrelated inhibitors, including caesium chloride. We have selected multicopy extragenic suppressor genes, revealing that this phenotype can be suppressed by overdosing the transcription factors BDF1 and GAT1 in the yaf9Delta strain. We focused our analysis on suppression by BDF1 and performed a genome-wide transcript analysis on a yaf9Delta strain, compared with the wild-type and BDF1-suppressed strains.

Alpha-Ketoglutarate dehydrogenase and lipoic acid synthase are important for the functioning of peroxisomes of Saccharomyces cerevisiae.

A method was devised to search for yeast mutants impaired in peroxisome functioning, indicating cross-talk between metabolic pathways. Two mutants were isolated; they are impaired in oleate utilisation and carry mutations in the KGD1 and LIP5 genes encoding the E1 component of the mitochondrial alpha-ketoglutarate dehydrogenase complex and lipoic acid synthase, respectively. The results presented indicate that the Kgd1 and Lip5 proteins are important for the expression of genes encoding peroxisomal matrix proteins, although they are not necessary for the biogenesis of this cellular compartment.

Functional and physical interactions of Faf1p, a Saccharomyces cerevisiae nucleolar protein.

We report the discovery and characterisation of a novel nucleolar protein of Saccharomyces cerevisiae. We identified this protein encoded by ORF YIL019w, designated in SGD base as Faf1p, in a two hybrid interaction screen using the known nucleolar protein Krr1 as bait. The presented data indicate that depletion of the Faf1 protein has an impact on the 40S ribosomal subunit biogenesis resulting from a decrease in the production of 18S rRNA.