60 research outputs found
A Drosophila melanogaster model for TMEM43-related arrhythmogenic right ventricular cardiomyopathy type 5
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a severe cardiac disease that leads to heart failure or sudden cardiac death (SCD). For the pathogenesis of ARVC, various mutations in at least eight different genes have been identified. A rare form of ARVC is associated with the mutation TMEM43 p.S358L, which is a fully penetrant variant in male carriers. TMEM43 p.S358 is homologous to CG8111 p.S333 in Drosophila melanogaster. We established CRISPR/Cas9-mediated CG8111 knock-out mutants in Drosophila, as well as transgenic fly lines carrying an overexpression construct of the CG8111 p.S333L substitution. Knock-out flies developed normally, whereas the overexpression of CG8111 p.S333L caused growth defects, loss of body weight, cardiac arrhythmias, and premature death. An evaluation of a series of model mutants that replaced S333 by selected amino acids proved that the conserved serine is critical for the physiological function of CG8111. Metabolomic and proteomic analyses revealed that the S333 in CG8111 is essential to proper energy homeostasis and lipid metabolism in the fly. Of note, metabolic impairments were also found in the murine Tmem43 disease model, and fibrofatty replacement is a hallmark of human ARVC5. These findings contribute to a more comprehensive understanding of the molecular functions of CG8111 in Drosophila, and can represent a valuable basis to assess the aetiology of the human TMEM43 p.S358L variant in more detail. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00018-022-04458-0
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Histone deacetylase inhibitors induce apoptosis in myeloid leukemia by suppressing autophagy
Histone deacetylase (HDAC)-inhibitors (HDACis) are well characterized anti-cancer agents with promising results in clinical trials. However, mechanistically little is known regarding their selectivity in killing malignant cells while sparing normal cells. Gene expression-based chemical genomics identified HDACis as being particularly potent against Down syndrome associated myeloid leukemia (DS-AMKL) blasts. Investigating the anti-leukemic function of HDACis revealed their transcriptional and posttranslational regulation of key autophagic proteins, including ATG7. This leads to suppression of autophagy, a lysosomal degradation process that can protect cells against damaged or unnecessary organelles and protein aggregates. DS-AMKL cells exhibit low baseline autophagy due to mTOR activation. Consequently, HDAC inhibition repressed autophagy below a critical threshold, which resulted in accumulation of mitochondria, production of reactive oxygen species, DNA-damage and apoptosis. Those HDACi-mediated effects could be reverted upon autophagy activation or aggravated upon further pharmacological or genetic inhibition. Our findings were further extended to other major acute myeloid leukemia subgroups with low basal level autophagy. The constitutive suppression of autophagy due to mTOR activation represents an inherent difference between cancer and normal cells. Thus, via autophagy suppression, HDACis deprive cells of an essential pro-survival mechanism, which translates into an attractive strategy to specifically target cancer cells
Recessive <i>HYDIN</i> mutations cause primary ciliary dyskinesia without randomization of left-right body asymmetry
Primary ciliary dyskinesia (PCD) is a genetically heterogeneous
recessive disorder characterized by defective cilia and flagella
motility. Chronic destructive-airway disease is caused by
abnormal respiratory-tract mucociliary clearance. Abnormal
propulsion of sperm flagella contributes to male infertility.
Genetic defects in most individuals affected by PCD cause
randomization of left-right body asymmetry; approximately half
show situs inversus or situs ambiguous. Almost 70 years after
the hy3 mouse possessing Hydin mutations was described as a
recessive hydrocephalus model, we report HYDIN mutations in PCD-
affected persons without hydrocephalus. By homozygosity mapping,
we identified a PCD-associated locus, chromosomal region 16q21-
q23, which contains HYDIN. However, a nearly identical 360 kb
paralogous segment (HYDIN2) in chromosomal region 1q21.1
complicated mutational analysis. In three affected German
siblings linked to HYDIN, we identified homozygous c.3985G>T
mutations that affect an evolutionary conserved splice acceptor
site and that subsequently cause aberrantly spliced transcripts
predicting premature protein termination in respiratory cells.
Parallel whole-exome sequencing identified a homozygous nonsense
HYDIN mutation, c.922A>T (p.Lys307( *)), in six individuals from
three Faroe Island PCD-affected families that all carried an 8.8
Mb shared haplotype across HYDIN, indicating an ancestral
founder mutation in this isolated population. We demonstrate by
electron microscopy tomography that, consistent with the effects
of loss-of-function mutations, HYDIN mutant respiratory cilia
lack the C2b projection of the central pair (CP) apparatus;
similar findings were reported in Hydin-deficient Chlamydomonas
and mice. High-speed videomicroscopy demonstrated markedly
reduced beating amplitudes of respiratory cilia and stiff sperm
flagella. Like the hy3 mouse model, all nine PCD-affected
persons had normal body composition because nodal cilia function
is apparently not dependent on the function of the CP
apparatus
Schwamm drĂŒber: Mal schnell mit Wasser und SpĂŒli ĂŒber die Arbeitsplatte wischen, reicht das fĂŒr ein reines Gewissen? Oder mĂŒssen hĂ€rtere GeschĂŒtze her? Zwei Experten erklĂ€ren in sieben Schritten, wie man richtig putzt
Chemical surface modification of silica nanoparticles for the labeling of DNA in lipoplexes
Les nanoparticules de silice sont des plateformes idĂ©ales pour la conception dâoutils de bioimagerie afin dâĂ©tudier les mĂ©canismes de transfert de gĂšnes par des lipoplexes. Lâobjectif de notre Ă©tude est le dĂ©veloppement dâune modification chimique de surface permettant dâobtenir des colloĂŻdes de silice chargĂ©s positivement susceptible de lier de lâADN par des interactions Ă©lectrostatiques. Deux stratĂ©gies pour la gĂ©nĂ©ration de groupements ammonium quaternaires sur des nanoparticules de silice sont prĂ©sentĂ©es a) une silanisation directe par lâutilisation dâun agent de couplage silanique contenant un groupement ammonium quaternaire et b) un procĂ©dĂ© en deux Ă©tapes mettant en jeu une modification de surface chimique par des aminosilanes primaires et secondaires suivie dâune alkylation des amines par lâiodomethane. DiffĂ©rentes mĂ©thodes physico-chimiques (essais de cosĂ©dimentation, des expĂ©riences de microbalance Ă cristal de quartz avec mesure de dissipation et dâimagerie MET et Cryo-MET) ont Ă©tĂ© utilisĂ©es pour mettre en Ă©vidence et caractĂ©riser les interactions entre les biomolĂ©cules et les surfaces quaternisĂ©es. Des Ă©tudes prĂ©liminaires ont montrĂ©es les capacitĂ©s de marquage de lipoplexes par de telles nanoparticules.Silica nanoparticles are ideal platforms for the conception of bioimaging tools serving for the elucidation of the mechanisms of gene transfection via lipoplex structures. The purpose of the present study is the development of a chemical surface modification for the generation of quaternary ammonium groups on silica nanoparticles permitting the obtainment of highly positively charged silica colloids which strongly attract DNA by electrostatic interactions. Two modification strategies to generate quaternary ammonium groups on silica are presented a) a direct silanization using quaternary ammonium groups containing silane derivatives and b) a modification of silica nanoparticles via a first modification with an amine group containing silane derivative and a subsequent quaternization of the amine groups via an alkylation with iodomethane. Different physicochemical methods were employed (cosedimentation assays, quartz crystal microbalance with dissipation monitoring measurements, TEM and Cryo-TEM imaging) to analyze interactions between quaternized surfaces, DNA and lipids. A preliminary study was carried out which shows the capacity of the synthesized nanoparticles to label DNA in lipoplexes
Chemical surface modification of silica nanoparticles for the labeling of DNA in lipoplexes
Les nanoparticules de silice sont des plateformes idĂ©ales pour la conception dâoutils de bioimagerie afin dâĂ©tudier les mĂ©canismes de transfert de gĂšnes par des lipoplexes. Lâobjectif de notre Ă©tude est le dĂ©veloppement dâune modification chimique de surface permettant dâobtenir des colloĂŻdes de silice chargĂ©s positivement susceptible de lier de lâADN par des interactions Ă©lectrostatiques. Deux stratĂ©gies pour la gĂ©nĂ©ration de groupements ammonium quaternaires sur des nanoparticules de silice sont prĂ©sentĂ©es a) une silanisation directe par lâutilisation dâun agent de couplage silanique contenant un groupement ammonium quaternaire et b) un procĂ©dĂ© en deux Ă©tapes mettant en jeu une modification de surface chimique par des aminosilanes primaires et secondaires suivie dâune alkylation des amines par lâiodomethane. DiffĂ©rentes mĂ©thodes physico-chimiques (essais de cosĂ©dimentation, des expĂ©riences de microbalance Ă cristal de quartz avec mesure de dissipation et dâimagerie MET et Cryo-MET) ont Ă©tĂ© utilisĂ©es pour mettre en Ă©vidence et caractĂ©riser les interactions entre les biomolĂ©cules et les surfaces quaternisĂ©es. Des Ă©tudes prĂ©liminaires ont montrĂ©es les capacitĂ©s de marquage de lipoplexes par de telles nanoparticules.Silica nanoparticles are ideal platforms for the conception of bioimaging tools serving for the elucidation of the mechanisms of gene transfection via lipoplex structures. The purpose of the present study is the development of a chemical surface modification for the generation of quaternary ammonium groups on silica nanoparticles permitting the obtainment of highly positively charged silica colloids which strongly attract DNA by electrostatic interactions. Two modification strategies to generate quaternary ammonium groups on silica are presented a) a direct silanization using quaternary ammonium groups containing silane derivatives and b) a modification of silica nanoparticles via a first modification with an amine group containing silane derivative and a subsequent quaternization of the amine groups via an alkylation with iodomethane. Different physicochemical methods were employed (cosedimentation assays, quartz crystal microbalance with dissipation monitoring measurements, TEM and Cryo-TEM imaging) to analyze interactions between quaternized surfaces, DNA and lipids. A preliminary study was carried out which shows the capacity of the synthesized nanoparticles to label DNA in lipoplexes
Chemical surface modification of silica nanoparticles for the labeling of DNA in lipoplexes
Les nanoparticules de silice sont des plateformes idĂ©ales pour la conception dâoutils de bioimagerie afin dâĂ©tudier les mĂ©canismes de transfert de gĂšnes par des lipoplexes. Lâobjectif de notre Ă©tude est le dĂ©veloppement dâune modification chimique de surface permettant dâobtenir des colloĂŻdes de silice chargĂ©s positivement susceptible de lier de lâADN par des interactions Ă©lectrostatiques. Deux stratĂ©gies pour la gĂ©nĂ©ration de groupements ammonium quaternaires sur des nanoparticules de silice sont prĂ©sentĂ©es a) une silanisation directe par lâutilisation dâun agent de couplage silanique contenant un groupement ammonium quaternaire et b) un procĂ©dĂ© en deux Ă©tapes mettant en jeu une modification de surface chimique par des aminosilanes primaires et secondaires suivie dâune alkylation des amines par lâiodomethane. DiffĂ©rentes mĂ©thodes physico-chimiques (essais de cosĂ©dimentation, des expĂ©riences de microbalance Ă cristal de quartz avec mesure de dissipation et dâimagerie MET et Cryo-MET) ont Ă©tĂ© utilisĂ©es pour mettre en Ă©vidence et caractĂ©riser les interactions entre les biomolĂ©cules et les surfaces quaternisĂ©es. Des Ă©tudes prĂ©liminaires ont montrĂ©es les capacitĂ©s de marquage de lipoplexes par de telles nanoparticules.Silica nanoparticles are ideal platforms for the conception of bioimaging tools serving for the elucidation of the mechanisms of gene transfection via lipoplex structures. The purpose of the present study is the development of a chemical surface modification for the generation of quaternary ammonium groups on silica nanoparticles permitting the obtainment of highly positively charged silica colloids which strongly attract DNA by electrostatic interactions. Two modification strategies to generate quaternary ammonium groups on silica are presented a) a direct silanization using quaternary ammonium groups containing silane derivatives and b) a modification of silica nanoparticles via a first modification with an amine group containing silane derivative and a subsequent quaternization of the amine groups via an alkylation with iodomethane. Different physicochemical methods were employed (cosedimentation assays, quartz crystal microbalance with dissipation monitoring measurements, TEM and Cryo-TEM imaging) to analyze interactions between quaternized surfaces, DNA and lipids. A preliminary study was carried out which shows the capacity of the synthesized nanoparticles to label DNA in lipoplexes
Modification chimique de surface de nanoparticules de silice pour le marquage d'ADN dans des lipoplexes
Silica nanoparticles are ideal platforms for the conception of bioimaging tools serving for the elucidation of the mechanisms of gene transfection via lipoplex structures. The purpose of the present study is the development of a chemical surface modification for the generation of quaternary ammonium groups on silica nanoparticles permitting the obtainment of highly positively charged silica colloids which strongly attract DNA by electrostatic interactions. Two modification strategies to generate quaternary ammonium groups on silica are presented a) a direct silanization using quaternary ammonium groups containing silane derivatives and b) a modification of silica nanoparticles via a first modification with an amine group containing silane derivative and a subsequent quaternization of the amine groups via an alkylation with iodomethane. Different physicochemical methods were employed (cosedimentation assays, quartz crystal microbalance with dissipation monitoring measurements, TEM and Cryo-TEM imaging) to analyze interactions between quaternized surfaces, DNA and lipids. A preliminary study was carried out which shows the capacity of the synthesized nanoparticles to label DNA in lipoplexes.Les nanoparticules de silice sont des plateformes idĂ©ales pour la conception dâoutils de bioimagerie afin dâĂ©tudier les mĂ©canismes de transfert de gĂšnes par des lipoplexes. Lâobjectif de notre Ă©tude est le dĂ©veloppement dâune modification chimique de surface permettant dâobtenir des colloĂŻdes de silice chargĂ©s positivement susceptible de lier de lâADN par des interactions Ă©lectrostatiques. Deux stratĂ©gies pour la gĂ©nĂ©ration de groupements ammonium quaternaires sur des nanoparticules de silice sont prĂ©sentĂ©es a) une silanisation directe par lâutilisation dâun agent de couplage silanique contenant un groupement ammonium quaternaire et b) un procĂ©dĂ© en deux Ă©tapes mettant en jeu une modification de surface chimique par des aminosilanes primaires et secondaires suivie dâune alkylation des amines par lâiodomethane. DiffĂ©rentes mĂ©thodes physico-chimiques (essais de cosĂ©dimentation, des expĂ©riences de microbalance Ă cristal de quartz avec mesure de dissipation et dâimagerie MET et Cryo-MET) ont Ă©tĂ© utilisĂ©es pour mettre en Ă©vidence et caractĂ©riser les interactions entre les biomolĂ©cules et les surfaces quaternisĂ©es. Des Ă©tudes prĂ©liminaires ont montrĂ©es les capacitĂ©s de marquage de lipoplexes par de telles nanoparticules
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