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BioRxiv : the Preprint Server For... Jul 2023TorsinA is an atypical ATPase that lacks intrinsic activity unless it is bound to its activators lamina-associated polypeptide 1 (LAP1) in the perinuclear space or...
TorsinA is an atypical ATPase that lacks intrinsic activity unless it is bound to its activators lamina-associated polypeptide 1 (LAP1) in the perinuclear space or luminal domain-like LAP1 (LULL1) throughout the endoplasmic reticulum. However, the interaction of torsinA with LAP1 and LULL1 has not yet been shown to modulate a defined physiological process in mammals . We previously demonstrated that depletion of torsinA from mouse hepatocytes leads to reduced liver triglyceride secretion and marked steatosis, whereas depletion of LAP1 had more modest similar effects. We now show that depletion of LULL1 alone does not significantly decrease liver triglyceride secretion or cause steatosis. However, simultaneous depletion of both LAP1 and LULL1 from hepatocytes leads to defective triglyceride secretion and marked steatosis similar to that observed with depletion of torsinA. Our results demonstrate that torsinA and its activators dynamically regulate a physiological process in mammals .
PubMed: 37547008
DOI: 10.1101/2023.06.21.545957 -
Experimental Medicine and Surgery 1963
Topics: Cell Biology; Enzymes; Golgi Apparatus; Guinea Pigs; Histocytochemistry; Myocardium; Nuclear Envelope; Rats; Research
PubMed: 14121000
DOI: No ID Found -
Archives of Virology Dec 2001The exact intracellular site of hepatitis A virus (HAV) production is unknown, possibly due to its usually slow and inefficient replication. Using immunocytochemistry...
The exact intracellular site of hepatitis A virus (HAV) production is unknown, possibly due to its usually slow and inefficient replication. Using immunocytochemistry and in-situ RT-PCR, we show that in cells infected with the rapidly replicating HAV strain HAS-15, viral proteins and RNA are scattered throughout the cytoplasm and accumulate in the perinuclear cytoplasmic area. Various ultrastructural alterations were found in infected cells, such as large polyribosomes, swelling of the perinuclear space and the ER, and dilatation of Golgi cisternae. In addition, HAV infection induced the formation of large arrays of annulate lamellae. Direct visualization of HAV particles was scarce. The various ultrastructural alterations described here might represent different phases of the replicative cycle of HAV that is asynchronous in the infected cell layer.
Topics: Animals; Cell Line; Cytoplasm; Endoplasmic Reticulum; Golgi Apparatus; Hepatitis A virus; Immunohistochemistry; Kidney; Microscopy, Electron; Organelles; Polyribosomes; RNA, Viral; Reverse Transcriptase Polymerase Chain Reaction; Viral Proteins; Virion; Virus Replication
PubMed: 11811680
DOI: 10.1007/s007050170003 -
Mass Spectrometry (Tokyo, Japan) 2023Aberrant glycosylation of membrane proteins is a hallmark of cancer and a useful molecular marker for the diagnosis of breast cancer (BC). However, the molecular...
Aberrant glycosylation of membrane proteins is a hallmark of cancer and a useful molecular marker for the diagnosis of breast cancer (BC). However, the molecular mechanisms by which altered glycosylation affects the malignant transformations associated with BC are poorly understood. Accordingly, we performed comparative membrane -glycoproteomics using the human BC cell line pair, Hs578T, and its syngeneic normal cell line, Hs578Bst. A total of 359 -glycoforms derived from 113 proteins were identified in both cell lines, of which 27 were found only in Hs578T cells. Significant changes in -glycosylation were found in the lysosome-associated membrane protein 1 (LAMP1), the integrin family, and laminin. Confocal immunofluorescence microscopy images revealed the accumulation of lysosomes in the perinuclear space in cancer cells, which could be associated with marked changes in LAMP1 glycosylation, such as a decreased level of polylactosamine chains. Overall, the alterations in glycosylation may be involved in changes in the adhesion and degradation of BC cells.
PubMed: 37250596
DOI: 10.5702/massspectrometry.A0117 -
Cellular and Molecular Bioengineering Jun 2016Mechanical forces generated by nuclear-cytoskeletal coupling through the LINC (linker of nucleoskeleton and cytoskeleton) complex, an evolutionarily conserved molecular...
Mechanical forces generated by nuclear-cytoskeletal coupling through the LINC (linker of nucleoskeleton and cytoskeleton) complex, an evolutionarily conserved molecular bridge in the nuclear envelope (NE), are critical for the execution of wholesale nuclear positioning events in migrating and dividing cells, chromosome dynamics during meiosis, and mechanotransduction. LINC complexes consist of outer (KASH (, and homology)) and inner (SUN ()) nuclear membrane proteins. KASH proteins interact with the cytoskeleton in the cytoplasm and SUN proteins in the perinuclear space of the NE. In the nucleoplasm, SUN proteins interact with A-type nuclear lamins and chromatin-binding proteins. Recent structural insights into the KASH-SUN interaction have generated several questions regarding how LINC complex assembly and function might be regulated within the perinuclear space. Here we discuss potential LINC regulatory mechanisms and focus on the potential role of AAA+ (ATPases associated with various cellular activities) protein, torsinA, as a LINC complex regulator within the NE. We also examine how defects in LINC complex regulation by torsinA may contribute to the pathogenesis of the human neurological movement disorder, DYT1 dystonia.
PubMed: 27499815
DOI: 10.1007/s12195-016-0432-0 -
Surgical Pathology Clinics Mar 2023CDC73 alterations are associated with three main parathyroid lesions according to the World Health Organization (WHO) classification of tumors of the endocrine system.... (Review)
Review
CDC73 alterations are associated with three main parathyroid lesions according to the World Health Organization (WHO) classification of tumors of the endocrine system. These include hyperparathyroidism-jaw tumor (HPT-JT) syndrome-associated adenomas, atypical parathyroid tumors (APTs), and parathyroid carcinomas (PCs). The loss of nuclear parafibromin expression, which serves as a surrogate marker for the underlying CDC73 alteration, encompasses these tumors under the term parafibromin-deficient parathyroid tumors. They have distinct morphologic features of more abundant eosinophilic cytoplasm with perinuclear clearing surrounding a large nucleus as well as prominent dilated branching "hemangiopericytoma-like" vasculature and a thick capsule as well as variably sized cystic spaces. These tumors include cases that show unequivocal histologic features fulfilling the criteria for PCs with growing data indicating a higher rate of recurrence or metastasis compared with parafibromin intact PCs. More importantly, the loss of parafibromin expression can be used in clinical practice to recognize APTs that fall short of a conclusive diagnosis of PCs, but clinically behave akin to them. Moreover, recognizing these tumors can lead to an underlying germline mutation and a diagnosis of HPT-JT, which impacts long-term treatment and surveillance for patients and close family.
Topics: Humans; Parathyroid Neoplasms; Tumor Suppressor Proteins; Hyperparathyroidism; Jaw Neoplasms; Neoplastic Syndromes, Hereditary; Transcription Factors
PubMed: 36739170
DOI: 10.1016/j.path.2022.09.009 -
Chromosome Research : An International... Dec 2010Specific nuclear domains are nonrandomly positioned within the nuclear space, and this preferential positioning has been shown to play an important role in genome...
Specific nuclear domains are nonrandomly positioned within the nuclear space, and this preferential positioning has been shown to play an important role in genome activity and stability. Well-known examples include the organization of repetitive DNA in telomere clusters or in the chromocenter of Drosophila and mammalian cells, which may provide a means to control the availability of general repressors, such as the heterochromatin protein 1 (HP1). We have specifically characterized the intranuclear positioning of in vivo fluorescence of the Caenorhabditis elegans HP1 homologue HPL-2 as a marker for heterochromatin domains in developing embryos. For this purpose, the wavelet transform modulus maxima (WTMM) segmentation method was generalized and adapted to segment the small embryonic cell nuclei in three dimensions. The implementation of a radial distribution algorithm revealed a preferential perinuclear positioning of HPL-2 fluorescence in wild-type embryos compared with the diffuse and homogeneous nuclear fluorescence observed in the lin-13 mutants. For all other genotypes analyzed, the quantitative analysis highlighted various degrees of preferential HPL-2 positioning at the nuclear periphery, which directly correlates with the number of HPL-2 foci previously counted on 2D projections. Using a probabilistic 3D cell nuclear model, we found that any two nuclei having the same number of foci, but with a different 3D probabilistic positioning scheme, can have significantly different counts in the 2D maximum projection, thus showing the deceptive limitations of using techniques of 2D maximum projection foci counts. By this approach, a strong perinuclear positioning of HPL-2 foci was brought into light upon inactivation of conserved chromatin-associated proteins, including the HAT cofactor TRAPP.
Topics: Animals; Caenorhabditis elegans; Cell Nucleus; Chromobox Protein Homolog 5; Chromosomal Proteins, Non-Histone; Embryonic Development; Heterochromatin; Imaging, Three-Dimensional; Models, Biological; Wavelet Analysis
PubMed: 21116703
DOI: 10.1007/s10577-010-9175-2 -
Biochemical Society Transactions Dec 2011Providing a stable physical connection between the nucleus and the cytoskeleton is essential for a wide range of cellular functions and it could also participate in... (Review)
Review
Providing a stable physical connection between the nucleus and the cytoskeleton is essential for a wide range of cellular functions and it could also participate in mechanosensing by transmitting intra- and extra-cellular mechanical stimuli via the cytoskeleton to the nucleus. Nesprins and SUN proteins, located at the nuclear envelope, form the LINC (linker of nucleoskeleton and cytoskeleton) complex that connects the nucleus to the cytoskeleton; underlying nuclear lamins contribute to anchoring LINC complex components at the nuclear envelope. Disruption of the LINC complex or loss of lamins can result in disturbed perinuclear actin and intermediate filament networks and causes severe functional defects, including impaired nuclear positioning, cell polarization and cell motility. Recent studies have identified the LINC complex as the major force-transmitting element at the nuclear envelope and suggest that many of the aforementioned defects can be attributed to disturbed force transmission between the nucleus and the cytoskeleton. Thus mutations in nesprins, SUN proteins or lamins, which have been linked to muscular dystrophies and cardiomyopathies, may weaken or completely eliminate LINC complex function at the nuclear envelope and result in impaired intracellular force transmission, thereby disrupting critical cellular functions.
Topics: Animals; Biomechanical Phenomena; Cell Nucleus; Cytoskeleton; Humans; Intracellular Space; Membrane Proteins; Multiprotein Complexes
PubMed: 22103516
DOI: 10.1042/BST20110686 -
Cellular and Molecular Neurobiology Nov 2023Isolated exposure to intermittent hypoxia and permissive hypercapnia activates signaling mechanisms that induce ultrastructural changes in mitochondria and endoplasmic...
Isolated exposure to intermittent hypoxia and permissive hypercapnia activates signaling mechanisms that induce ultrastructural changes in mitochondria and endoplasmic reticulum, accompanied by the development of maximal ischemic tolerance in neurons under the combined influence of these factors. However, there are a lack of data on the combined impact of these factors on the ultrastructure of neuronal organelles. The present study aims to comparatively assess the ultrastructural changes in neurons following isolated and combined exposure to hypoxia and hypercapnia, as well as to correlate these changes with the neuroprotective potential previously observed for these factors. Following a 15-session course of 30-min exposures to permissive hypercapnia (P ≈ 50 mmHg) and/or normobaric hypoxia (P ≈ 150 mmHg), morphometric assessment was conducted to evaluate the extent of ultrastructural changes in hippocampal neurons (mitochondria, perinuclear space, and granular endoplasmic reticulum). It was found that in hippocampal neurons from the CA1 region, permissive hypercapnia resulted in increased mitochondrial size, expansion of membranous compartments of the granular endoplasmic reticulum, and perinuclear space. Normobaric hypoxia affected only mitochondrial size, while hypercapnic hypoxia specifically widened the perinuclear space. These ultrastructural changes objectively reflect varying degrees of the influence of hypoxia and hypercapnia on organelles responsible for energy metabolism, anti-apoptotic, and synthetic functions of neurons. This confirms the effect of potentiation of their neuroprotective effects under combined exposure and highlights the dominant role of the hypercapnic component in this mechanism.
Topics: Humans; Hypercapnia; Hypoxia; Neurons; Cerebral Cortex; Hippocampus
PubMed: 37716927
DOI: 10.1007/s10571-023-01407-8 -
Experimental Medicine and Surgery 1965
Topics: Animals; Fishes; Histology, Comparative; In Vitro Techniques; Microscopy, Electron; Myocardium; Sharks
PubMed: 5843915
DOI: No ID Found