Role of Lamina-associated polypeptide 2 alpha in striated muscle differentiation and regeneration

Lamina-assoziiertes Polypeptid 2 alpha (LAP2 alpha) ist ein nucleoplasmatisches Protein, welches spezifisch in Säugerzellen expremiert wird. Durch die Interaktion mit A-Typ Laminen und dem Retinoblastoma Protein ist es in die Regulation des Zellzyklus involviert. Mutationen in Lamin A/C und LAP2 alpha können zu Krankheiten im Menschen führen, die Laminopathien genannt werden und bei welchen am häufigsten die quergestreifte Muskulatur betroffen ist. Ich habe die strukturellen und funktionellen Eigenschaften von Herz-und Skelettmuskulatur in kompletten sowie gewebsspezifisch-konditionellen LAP2 alpha knockout Mäusen analysiert, um einen Einblick in die molekularen Mechanismen zu bekommen, die den Erkrankungen zu Grunde liegen. Das Fehlen von LAP2 alpha in Mäusen verursachte einen ähnlichen Phenotyp, wie die Mutation des Genes im Menschen. Die Mäuse weisen eine verminderte Funktionalität des Herzens und eine erhöhte Anfälligkeit für Fibrose im Myokard im vorangeschrittenen Alter auf. Auf molekularer Ebene führte das Fehlen von LAP2 alpha zu einer Deregulation der für die Herzentwicklung wichtigen Transkriptionsfaktoren GATA4 und MEF2c, sowie deren Zielgene. Die Aktivierung von Kompensationsmechanismen im Herz der Lap2 alpha-/- Maus hatte eine verminderte Aktivität des beta-adrenergen Rezeptors zur Folge. Die dadurch herbeigeführte reduzierte beta-adrenerge Stimulationsfähigkeit des Myokards verhinderte eine weitere Progression der Hypertrophie, welche andernfalls zum Versagen der Herztätigkeit geführt hätte. Andererseits führte eine Dystrophin-Defizienz in einem genetischen “Mdx“ Hintergrund zu einer transienten Aufhebung des LAP2 alpha-null Phenotyps. Die Morphologie, Funktion und Regeneration der Skelettmuskulatur in der Lap2 alpha-/- Maus zeigte in vivo keine offensichtlichen Veränderungen. Nichtsdestotrotz führte das Fehlen von LAP2 alpha zu einer erhöhten Anzahl von Muskelfaser-assoziierten Stammzellen, welche eine verzögerte myogene in vitro Differenzierung aufwiesen. Zusätzlich verschob sich durch die Abwesenheit von LAP2 alpha das Verhältnis der unterschiedlichen Muskelfasertypen von langsamen zu schnellen Fasertypen. Zusammenfassend weisen diese Ergebnisse auf eine neue Rolle von LAP2 alpha in der Erhaltung der physiologischen Funktionen des Herzens unter Stress- und Normalbedingungen hin. Im Weiteren zeigen die erhaltenen Daten eine weitere Funktion von LAP2 alpha in der Skelettmuskulatur, speziell in der Homöostase der Satellitenzellen und der frühen myogenen Differenzierung, sowie in der Determinierung des Muskelfasertyps und der Muskelremodellierung.Lamina-associated polypeptide 2 alpha (LAP2 alpha) is a mammalian nucleoplasmic protein implicated in cell cycle regulation through its interaction with A-type lamins and the retinoblastoma protein (pRb). Mutations in lamin A/C and LAP2 alpha cause a variety of pathological human conditions, collectively termed laminopathies. One of the tissues most frequently affected by changes in genes encoding lamin A/C and LAP2 alpha is striated muscle. To elucidate the molecular mechanisms underlying these severe conditions and study the role of LAP2 alpha in striated muscle tissue, I analyzed the structural and functional properties of heart and skeletal muscle in complete and conditional tissue-specific LAP2 alpha knockout mice. Similar to the human condition caused by a mutation in LAP2 alpha, complete knockout of the gene impaired heart function in mice and rendered the myocardium more susceptible to fibrosis with advancing age. At the molecular level, loss of LAP2 alpha caused a deregulation of major cardiac transcription factors GATA4 and MEF2c, as well as their tissue-specific target genes. Activation of compensatory pathways in LAP2 alpha-deficient hearts resulted in downregulation of beta-adrenergic receptor signaling and reduced responsiveness of the myocardium to chronic beta-adrenergic stimulation, stalling the progression from cardiac hypertrophy towards heart failure. On the other hand, dystrophin deficiency in an Mdx background resulted in a transient rescue of the Lap2 alpha-/- phenotype. Skeletal muscle of LAP2 alpha-deficient mice showed no overt defects in muscle morphology, function and regeneration in vivo. Nevertheless, the absence of LAP2 alpha caused an increase in the murine myofiber-associated muscle stem cell pool, which showed an enhanced stem cell-like phenotype and delayed myogenic differentiation in vitro. In addition, loss of LAP2 alpha shifted the myofiber type ratios of adult slow muscles towards fast fiber types. Altogether, these data suggest a novel role of LAP2 alpha in maintenance of cardiac function under normal and stress conditions and demonstrate a dual function of the protein in skeletal muscle tissue, namely in satellite cell maintenance and early myogenic differentiation, as well as myofiber type-specification and muscle remodeling

The effect of ultrafine WO3 nanoparticles on the organization of thylakoids enriched in photosystem II and energy transfer in photosystem II complexes

In this work, a new approach to construct self-assembled hybrid systems based on natural PSII-enriched thylakoid membranes (PSII BBY) is demonstrated. Superfine m-WO3 NPs (≈1–2 nm) are introduced into PSII BBY. Transmission electron microscopy (TEM) measurements showed that even the highest concentrations of NPs used did not degrade the PSII BBY membranes. Using atomic force microscopy (AFM), it is shown that the organization of PSII BBY depends strongly on the concentration of NPs applied. This proved that the superfine NPs can easily penetrate the thylakoid membrane and interact with its components. These changes are also related to the modified energy transfer between the external light-harvesting antennas and the PSII reaction center, shown by absorption and fluorescence experiments. The biohybrid system shows stability at pH 6.5, the native operating environment of PSII, so a high rate of O2 evolution is expected. In addition, the light-induced water-splitting process can be further stimulated by the direct interaction of superfine WO3 NPs with the donor and acceptor sides of PSII. The water-splitting activity and stability of this colloidal system are under investigation

Frequency of Aberrant Promoter Methylation of P15(Ink4b) and O-6-Methylguanine-Dna Methyltransferase Genes in B-Cell Non-Hodgkin Lymphoma: a Pilot Study

The methylation status of the target promoter sequences of p15(INK4B) (p15) and O-6-methylguanine-DNA methyltransferase (MGMT) genes was studied by methylation-specific PCR in 10 adult patients with de novo B-cell non-Hodgkin lymphoma (B-NHL). The aberrant hypermethylation of the p15 gene was more frequent (50%) compared to the hypermethylation of the MGMT gene (30%), and was detected in different types of B-NHL in both genes. Hypermethylation of the MGMT gene occurred exclusively in association with the hypermethylation of the p15 gene. All lymphoma patients with hypermethylation of the p15 and/or MGMT genes had a higher clinical stage of the disease (IV - V). We show the association of anemia and/or thrombocytopenia with the hypermethylation of the p15 gene, ascribing the p15 gene as a potential prognostic marker in B-NHL. Comethylation of MGMT with the p15 gene represents a novel finding and presents both genes as candidates for future studies of the hypermethylation profiles of B-NHL

Serum proteome profiling of naturally acquired Babesia rossi infection in dogs

DATA AVAILABILITY : The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE78 partner repository with the dataset identifier PXD039022 (https://www.ebi.ac.uk/pride/archive).Babesiosis is a disease of significant medically and veterinary importance with worldwide distribution. It is caused by intra-erythrocyte protozoal parasites, with Babesia rossi causing the most severe clinical signs of all the large Babesia parasites infecting dogs. The disease can be clinically classified into uncomplicated and complicated forms with a wide range of clinical presentations from a mild, subclinical illness to complicated forms and death. The aim of this study was to assess serum proteomic profiles from dogs with babesiosis and healthy dogs using a label-based proteomics approach. Altogether 32 dogs naturally infected with B. rossi (subdivided into 18 uncomplicated cases and 14 complicated cases of babesiosis) and 20 healthy dogs were included. There were 78 proteins with significantly different abundances between the three groups of dogs. Elucidation of proteins and pathways involved in canine babesiosis caused by B. rossi have revealed key differences associated with haemostasis, innate immune system, lipid metabolism and inflammation. Shotgun proteomic profiling allowed identification of potential serum biomarkers for differentiation of disease severity in canine babesiosis caused by B. rossi. These findings may be applicable to the study of host-parasite interactions and the development of novel therapeutic targets.The European Regional Development Fund.https://www.nature.com/srepam2024Companion Animal Clinical StudiesSDG-03:Good heatlh and well-bein

Differential expansion of circulating human MDSC subsets in patients with cancer, infection and inflammation

Background Myeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that includes myeloid cells with immune suppressive properties. The presence of MDSC has been reported in the peripheral blood of patients with several malignant and non-malignant diseases. So far, direct comparison of MDSC across different diseases and Centers is hindered by technical pitfalls and a lack of standardized methodology. To overcome this issue, we formed a network through the COST Action Mye-EUNITER (www.mye-euniter.eu) with the goal to standardize and facilitate the comparative analysis of human circulating MDSC in cancer, inflammation and infection. In this manuscript, we present the results of the multicenter study Mye-EUNITER MDSC Monitoring Initiative, that involved 13 laboratories and compared circulating MDSC subsets across multiple diseases, using a common protocol for the isolation, identification and characterization of these cells. Methods We developed, tested, executed and optimized a standard operating procedure for the isolation and immunophenotyping of MDSC using blood from healthy donors. We applied this procedure to the blood of almost 400 patients and controls with different solid tumors and non-malignant diseases. The latter included viral infections such as HIV and hepatitis B virus, but also psoriasis and cardiovascular disorders. Results We observed that the frequency of MDSC in healthy donors varied substantially between centers and was influenced by technical aspects such as the anticoagulant and separation method used. Expansion of polymorphonuclear (PMN)-MDSC exceeded the expansion of monocytic MDSC (M-MDSC) in five out of six solid tumors. PMN-MDSC expansion was more pronounced in cancer compared with infection and inflammation. Programmed death-ligand 1 was primarily expressed in M-MDSC and e-MDSC and was not upregulated as a consequence of disease. LOX-1 expression was confined to PMN-MDSC. Conclusions This study provides improved technical protocols and workflows for the multi-center analysis of circulating human MDSC subsets. Application of these workflows revealed a predominant expansion of PMN-MDSC in solid tumors that exceeds expansion in chronic infection and inflammation

Functional evolution of nuclear structure

The evolution of the nucleus, the defining feature of eukaryotic cells, was long shrouded in speculation and mystery. There is now strong evidence that nuclear pore complexes (NPCs) and nuclear membranes coevolved with the endomembrane system, and that the last eukaryotic common ancestor (LECA) had fully functional NPCs. Recent studies have identified many components of the nuclear envelope in living Opisthokonts, the eukaryotic supergroup that includes fungi and metazoan animals. These components include diverse chromatin-binding membrane proteins, and membrane proteins with adhesive lumenal domains that may have contributed to the evolution of nuclear membrane architecture. Further discoveries about the nucleoskeleton suggest that the evolution of nuclear structure was tightly coupled to genome partitioning during mitosis