The nuclear envelope (NE) is the central organizing unit of the eukaryotic cell serving as a genome protective barrier and mechanotransduction interface between the cytoplasm and the nucleus. The NE ...is mainly composed of a nuclear lamina and a double membrane connected at specific points where the nuclear pore complexes (NPCs) form. Physiological aging might be generically defined as a functional decline across lifespan observed from the cellular to organismal level. Therefore, during aging and premature aging, several cellular alterations occur, including nuclear‐specific changes, particularly, altered nuclear transport, increased genomic instability induced by DNA damage, and telomere attrition. Here, we highlight and discuss proteins associated with nuclear transport dysfunction induced by aging, particularly nucleoporins, nuclear transport factors, and lamins. Moreover, changes in the structure of chromatin and consequent heterochromatin rearrangement upon aging are discussed. These alterations correlate with NE dysfunction, particularly lamins’ alterations. Finally, telomere attrition is addressed and correlated with altered levels of nuclear lamins and nuclear lamina‐associated proteins. Overall, the identification of molecular mechanisms underlying NE dysfunction, including upstream and downstream events, which have yet to be unraveled, will be determinant not only to our understanding of several pathologies, but as here discussed, in the aging process.
Growing evidence has drawn attention to the nuclear envelope dysfunction as a hallmark of the aging process. Indeed, during aging and premature aging, several cellular alterations occur, including nuclear‐specific changes, particularly alterations in nuclear transport, chromatin organization, and telomere maintenance. Therefore, nuclear protein alterations are essential determinants of physiological and premature aging and may provide biomarkers for aging status and other pathologies like cancer.
Aging is a complex process which leads to progressive loss of fitness/capability/ability, increasing susceptibility to disease and, ultimately, death. Regardless of the organism, there are some ...features common to aging, namely, the loss of proteostasis and cell senescence. Mammalian cell lines have been used as models to study the aging process, in particular, cell senescence. Thus, the aim of this study was to characterize the senescence-associated metabolic profile of a long-term culture of human fibroblasts using Fourier Transform Infrared and Nuclear Magnetic Resonance spectroscopy. We sub-cultivated fibroblasts from a newborn donor from passage 4 to passage 17 and the results showed deep changes in the spectroscopic profile of cells over time. Late passage cells were characterized by a decrease in the length of fatty acid chains, triglycerides and cholesterol and an increase in lipid unsaturation. We also found an increase in the content of intermolecular β-sheets, possibly indicating an increase in protein aggregation levels in cells of later passages. Metabolic profiling by NMR showed increased levels of extracellular lactate, phosphocholine and glycine in cells at later passages. This study suggests that spectroscopy approaches can be successfully used to study changes concomitant with cell senescence and validate the use of human fibroblasts as a model to monitor the aging process.
ABSTRACT
The production of highly specialized spermatozoa from undifferentiated spermatogonia is a strictly organized and programmed process requiring extensive restructuring of the entire cell. One ...of the most remarkable cellular transformations accompanying the various phases of spermatogenesis is the profound remodelling of the nuclear architecture, in which the nuclear envelope (NE) seems to be crucially involved. In recent years, several proteins from the distinct layers forming the NE (i.e. the inner and outer nuclear membranes as well as the nuclear lamina) have been associated with meiosis and/or spermiogenesis in different mammalian species. Among these are A‐ and B‐type lamins, Dpy‐19‐like protein 2 (DPY19L2), lamin B receptor (LBR), lamina‐associated polypeptide 1 (LAP1), LAP2/emerin/MAN1 (LEM) domain‐containing proteins, spermatogenesis‐associated 46 (SPATA46) and diverse elements of the linker of nucleoskeleton and cytoskeleton (LINC) complex, namely Sad‐1/UNC‐84 homology (SUN) and Klarsicht/ANC‐1/Syne‐1 homology (KASH) domain‐containing proteins. Herein, we summarize the current state of the art on the cellular and subcellular distribution of NE proteins expressed during mammalian spermatogenesis, and discuss the latest research developments regarding their testis‐specific functions. This review provides a comprehensive and innovative overview of the NE network as a regulatory platform and as an essential determinant of efficient meiotic chromosome recombination as well as spermiogenesis‐associated nuclear remodelling and differentiation in mammalian male germline cells. Thus, this review provides important novel insights on the biological relevance of NE proteins for male fertility.
Neurons have a membrane periodic skeleton (MPS) composed of actin rings interconnected by spectrin. Here, combining chemical and genetic gain- and loss-of-function assays, we show that in rat ...hippocampal neurons the MPS is an actomyosin network that controls axonal expansion and contraction. Using super-resolution microscopy, we analyzed the localization of axonal non-muscle myosin II (NMII). We show that active NMII light chains are colocalized with actin rings and organized in a circular periodic manner throughout the axon shaft. In contrast, NMII heavy chains are mostly positioned along the longitudinal axonal axis, being able to crosslink adjacent rings. NMII filaments can play contractile or scaffolding roles determined by their position relative to actin rings and activation state. We also show that MPS destabilization through NMII inactivation affects axonal electrophysiology, increasing action potential conduction velocity. In summary, our findings open new perspectives on axon diameter regulation, with important implications in neuronal biology.
biomass, either from forest exploitation or from the management of invasive species, can be a strategic topic, namely as a source of high-value compounds. In this sense, the present study aimed at ...the detailed characterization of the lipophilic components of different morphological parts of
and the evaluation of their cytotoxicity in cells representative of different mammals' tissues. The chemical composition of lipophilic extracts from
bark, wood and leaves was evaluated using gas chromatography-mass spectrometry (GC-MS). Terpenic compounds (representing 50.2%-68.4% of the total bark and leaves extracts, respectively) and sterols (60.5% of the total wood extract) were the main components of these extracts. Other constituents, such as fatty acids, long-chain aliphatic alcohols, monoglycerides, and aromatic compounds were also detected in the studied extracts. All the extracts showed low or no cytotoxicity in the different cells tested, demonstrating their safety profile and highlighting their potential to be used in nutraceutical or pharmaceutical applications. This study is therefore an important contribution to the valorization of
, demonstrating the potential of this species as a source of high value lipophilic compounds.
Myotonic dystrophy type 1 (DM1) is a hereditary and multisystemic disease characterized by myotonia, progressive distal muscle weakness and atrophy. The molecular mechanisms underlying this disease ...are still poorly characterized, although there are some hypotheses that envisage to explain the multisystemic features observed in DM1. An emergent hypothesis is that nuclear envelope (NE) dysfunction may contribute to muscular dystrophies, particularly to DM1. Therefore, the main objective of the present study was to evaluate the nuclear profile of DM1 patient-derived and control fibroblasts and to determine the protein levels and subcellular distribution of relevant NE proteins in these cell lines. Our results demonstrated that DM1 patient-derived fibroblasts exhibited altered intracellular protein levels of lamin A/C, LAP1, SUN1, nesprin-1 and nesprin-2 when compared with the control fibroblasts. In addition, the results showed an altered location of these NE proteins accompanied by the presence of nuclear deformations (blebs, lobes and/or invaginations) and an increased number of nuclear inclusions. Regarding the nuclear profile, DM1 patient-derived fibroblasts had a larger nuclear area and a higher number of deformed nuclei and micronuclei than control-derived fibroblasts. These results reinforce the evidence that NE dysfunction is a highly relevant pathological characteristic observed in DM1.
Human ATP-binding cassette (ABC) transporters mediate a critical function in the cell, namely the transport of molecules across lipid membranes. Associated to their ubiquitous tissue distribution, ...they are key players in cellular homeostasis but also potential causative or contributing factors for many pathologies, including Alzheimer's disease (AD). In the central nervous system (CNS), numerous ABC transporters are present throughout the brain parenchyma and especially at the blood-brain barrier (BBB). AD is a neurodegenerative disorder mainly characterized by extracellular deposition of amyloid-β (Aβ) peptides and intracellular accumulation of hyperphosphorylated forms of tau protein. Besides being degraded via proteolytic and phagocytic processes mediated by brain parenchymal cells, a major mechanism for eliminating cerebral Aβ is through its transport across the BBB into the peripheral blood. In fact, many AD cases are associated with impaired Aβ clearance. Consistently, several studies have recently uncovered important roles for ABC transporters in AD pathophysiology. Hence, this review focuses on the relevance of ABC transporters in CNS homeostasis by highlighting AD as a strong example of the deleterious consequences that might result from the former's altered expression and/or activity in the brain. The potentiality of human ABC transporters as novel pharmacological targets for both the diagnosis and therapeutics of AD is emphasized.
Lamina-associated polypeptide 1 (LAP1) is a nuclear envelope (NE) protein whose function remains poorly characterized. In a recent LAP1 protein interactome study, a putative regulatory role in the ...DNA damage response (DDR) has emerged and telomeric repeat-binding factor 2 (TRF2), a protein intimately associated with this signaling pathway, was among the list of LAP1 interactors. To gain insights into LAP1's physiological properties, the interaction with TRF2 in human cells exposed to DNA-damaging agents was investigated. The direct LAP1:TRF2 binding was validated in vitro by blot overlay and in vivo by co-immunoprecipitation after hydrogen peroxide and bleomycin treatments. The regulation of this protein interaction by LAP1 phosphorylation was demonstrated by co-immunoprecipitation and mass spectrometry following okadaic acid exposure. The involvement of LAP1 and TRF2 in the DDR was confirmed by their increased nuclear protein levels after bleomycin treatment, evaluated by immunoblotting, as well as by their co-localization with DDR factors at the NE and within the nucleoplasm, assessed by immunocytochemistry. Effectively, we showed that the LAP1:TRF2 complex is established during a cellular response against DNA damage. This work proposes a novel functional role for LAP1 in the DDR, revealing a potential biological mechanism that may be disrupted in LAP1-associated pathologies.
Lamina-associated polypeptide 1 (LAP1), a ubiquitously expressed nuclear envelope protein, appears to be essential for the maintenance of cell homeostasis. Although rare, mutations in the human ...LAP1-encoding TOR1AIP1 gene cause severe diseases and can culminate in the premature death of affected individuals. Despite there is increasing evidence of the pathogenicity of TOR1AIP1 mutations, the current knowledge on LAP1's physiological roles in humans is limited; hence, investigation is required to elucidate the critical functions of this protein, which can be achieved by uncovering the molecular consequences of LAP1 depletion, a topic that remains largely unexplored. In this work, the proteome of patient-derived LAP1-deficient fibroblasts carrying a pathological TOR1AIP1 mutation (LAP1 E482A) was quantitatively analyzed to identify global changes in protein abundance levels relatively to control fibroblasts. An in silico functional enrichment analysis of the mass spectrometry-identified differentially expressed proteins was also performed, along with additional in vitro functional assays, to unveil the biological processes that are potentially dysfunctional in LAP1 E482A fibroblasts. Collectively, our findings suggest that LAP1 deficiency may induce significant alterations in various cellular activities, including DNA repair, messenger RNA degradation/translation, proteostasis and glutathione metabolism/antioxidant response. This study sheds light on possible new functions of human LAP1 and could set the basis for subsequent in-depth mechanistic investigations. Moreover, by identifying deregulated signaling pathways in LAP1-deficient cells, our work may offer valuable molecular targets for future disease-modifying therapies for TOR1AIP1-associated nuclear envelopathies.
Display omitted
•Proteome analysis of LAP1-deficient patient's cells reveals dysfunctional processes.•DNA repair, translation, proteostasis and oxidative stress response are deregulated.•LAP1 is required for the maintenance of genome integrity in a physiological state.•Potential therapeutic targets for LAP1-associated diseases are uncovered.
leaves have been mainly exploited for essential oil recovery or for energy generation in industrial pulp mills, neglecting the abundance of valuable families of extractives, namely, triterpenic ...acids, that might open new ways for the integrated valorization of this biomass. Therefore, this study highlights the lipophilic characterization of
leaves before and after hydrodistillation, aiming at the integrated valorization of both essential oils and triterpenic acids. The lipophilic composition of
leaves after hydrodistillation is reported for the first time. Extracts were obtained by dichloromethane Soxhlet extraction and analyzed by gas chromatography-mass spectrometry. In addition, their cytotoxicity on different cell lines representative of the innate immune system, skin, liver, and intestine were evaluated. Triterpenic acids, such as betulonic, oleanolic, betulinic and ursolic acids, were found to be the main components of these lipophilic extracts, ranging from 30.63-37.14 g kg
of dry weight (dw), and representing 87.7-89.0%
/
of the total content of the identified compounds. In particular, ursolic acid was the major constituent of all extracts, representing 46.8-50.7%
/
of the total content of the identified compounds. Other constituents, such as fatty acids, long-chain aliphatic alcohols and
-sitosterol were also found in smaller amounts in the studied extracts. This study also demonstrates that the hydrodistillation process does not affect the recovery of compounds of greatest interest, namely, triterpenic acids. Therefore, the results establish that this biomass residue can be considered as a promising source of value-added bioactive compounds, opening new strategies for upgrading pulp industry residues within an integrated biorefinery context.
PDF
