Hydrogen Peroxide Probes Directed to Different Cellular Compartments

Background: Controlled generation and removal of hydrogen peroxide play important roles in cellular redox homeostasis and signaling. We used a hydrogen peroxide biosensor HyPer, targeted to different compartments, to examine these processes in mammalian cells. Principal Findings: Reversible responses were observed to various redox perturbations and signaling events. HyPer expressed in HEK 293 cells was found to sense low micromolar levels of hydrogen peroxide. When targeted to various cellular compartments, HyPer occurred in the reduced state in the nucleus, cytosol, peroxisomes, mitochondrial intermembrane space and mitochondrial matrix, but low levels of the oxidized form of the biosensor were also observed in each of these compartments, consistent with a low peroxide tone in mammalian cells. In contrast, HyPer was mostly oxidized in the endoplasmic reticulum. Using this system, we characterized control of hydrogen peroxide in various cell systems, such as cells deficient in thioredoxin reductase, sulfhydryl oxidases or subjected to selenium deficiency. Generation of hydrogen peroxide could also be monitored in various compartments following signaling events. Conclusions: We found that HyPer can be used as a valuable tool to monitor hydrogen peroxide generated in different cellular compartments. The data also show that hydrogen peroxide generated in one compartment could translocate to other compartments. Our data provide information on compartmentalization, dynamics and homeostatic control of hydrogen peroxide in mammalian cells

Elternschlaf bei kindlichen Schlafbeschwerden - ein Überblick

Schlarb A, Kreienborg A-K, Peveling LS, Schneiders J, Bihlmaier I, Lollies F. Elternschlaf bei kindlichen Schlafbeschwerden - ein Überblick. Pädiatrische Praxis. Zeitschrift für Kinder- und Jugendmedizin in Klinik und Praxis. 2016;86(1):163-174

Biosynthetic Gene Cluster for the Polyenoyltetramic Acid α-Lipomycin

The gram-positive bacterium Streptomyces aureofaciens Tü117 produces the acyclic polyene antibiotic α-lipomycin. The entire biosynthetic gene cluster (lip gene cluster) was cloned and characterized. DNA sequence analysis of a 74-kb region revealed the presence of 28 complete open reading frames (ORFs), 22 of them belonging to the biosynthetic gene cluster. Central to the cluster is a polyketide synthase locus that encodes an eight-module system comprised of four multifunctional proteins. In addition, one ORF shows homology to those for nonribosomal peptide synthetases, indicating that α-lipomycin belongs to the classification of hybrid peptide-polyketide natural products. Furthermore, the lip cluster includes genes responsible for the formation and attachment of d-digitoxose as well as ORFs that resemble those for putative regulatory and export functions. We generated biosynthetic mutants by insertional gene inactivation. By analysis of culture extracts of these mutants, we could prove that, indeed, the genes involved in the biosynthesis of lipomycin had been cloned, and additionally we gained insight into an unusual biosynthesis pathway

Biosynthetic Gene Cluster of Simocyclinone, a Natural Multihybrid Antibiotic

The entire simocyclinone biosynthetic cluster (sim gene cluster) from the producer Streptomyces antibioticus Tü6040 was identified on six overlapping cosmids (1N1, 5J10, 2L16, 2P6, 4G22, and 1K3). In total, 80.7 kb of DNA from these cosmids was sequenced, and the analysis revealed 49 complete open reading frames (ORFs). These ORFs include genes responsible for the formation and attachment of four different moieties originating from at least three different pools of primary metabolites. Also in the sim gene cluster, four ORFs were detected that resemble putative regulatory and export functions. Based on the putative function of the gene products, a model for simocyclinone D8 biosynthesis was proposed. Biosynthetic mutants were generated by insertional gene inactivation experiments, and culture extracts of these mutants were analyzed by high-performance liquid chromatography. Production of simocyclinone D8 was clearly detectable in the wild-type strain but was not detectable in the mutant strains. This indicated that indeed the sim gene cluster had been cloned

The Level of ALR is Regulated by the Quantity of Mitochondrial DNA.

Augmenter of liver regeneration (ALR) contributes to mitochondrial biogenesis, maintenance and to the physiological operation of mitochondria. The depletion of ALR has been widely studied and had serious consequences on the mitochondrial functions. However the inverse direction, the effect of the depletion of mitochondrial electron transfer chain and mtDNA on ALR expression has not been investigated yet. Thus mtDNA depleted, rho0 cell line was prepared to investigate the role of mitochondrial electron transfer chain and mtDNA on ALR expression. The depletion of mtDNA has not caused any difference at mRNA level, but at protein level the expression of ALR has been markedly increased. The regulatory role of ATP and ROS levels could be ruled out because the treatment of the parental cell line with different respiratory inhibitors and uncoupling agent could not provoke any changes in the protein level of ALR. The effect of mtDNA depletion on the protein level of ALR has been proved not to be liver specific, since the phenomenon could be observed in the case of two other, non-hepatic cell lines. It seems the level of mtDNA and/or its products may have regulatory role on the protein level of ALR. The up-regulation of ALR can be a part of the adaptive response in rho0 cells that preserves the structural integrity and the transmembrane potential despite the absence of protein components encoded by the mtDNA