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Neurobiology of Disease Oct 1999Peripheral myelin protein 22 (PMP22) is a 22-kDa glycoprotein mainly expressed by Schwann cells (SCs). Duplication or deletion of the PMP22 gene locus is associated with...
Peripheral myelin protein 22 (PMP22) is a 22-kDa glycoprotein mainly expressed by Schwann cells (SCs). Duplication or deletion of the PMP22 gene locus is associated with heritable peripheral neuropathies suggesting that the correct level of PMP22 protein is essential for SC functioning. Previously we reported that in SCs the majority (80%) of newly synthesized PMP22 is rapidly degraded, possibly due to inefficient folding. Here we show that inhibition of the proteasome pathway results in a marked accumulation of PMP22 in the perinuclear cytoplasm. Double immunolabeling with an anti-ubiquitin antibody and various organelle markers indicates that the accumulated PMP22 is found in unique intracellular inclusions, called aggresomes. Moreover, overexpression of PMP22 in SCs can induce perinuclear accumulation of the protein. Together, these studies suggest that the proteasome pathway is critical for the regulation of PMP22 protein levels and raise the possibility that aggresomes may be involved in the pathogenesis of PMP22-associated peripheral neuropathies.
Topics: Animals; Animals, Newborn; Cells, Cultured; Charcot-Marie-Tooth Disease; Membrane Proteins; Myelin and Lymphocyte-Associated Proteolipid Proteins; Nerve Tissue Proteins; Organelles; Peripheral Nervous System Diseases; Proteolipids; Rats; Schwann Cells; Sciatic Nerve; Ubiquitins; Vimentin
PubMed: 10527811
DOI: 10.1006/nbdi.1999.0274 -
The Journals of Gerontology. Series A,... Jan 2021Fortetropin is a proteo-lipid complex made from fertilized egg yolk and, in young men, has been shown to increase lean body mass. (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Fortetropin is a proteo-lipid complex made from fertilized egg yolk and, in young men, has been shown to increase lean body mass.
METHODS
The purpose of this study was to examine the effects of 21 days of Fortetropin supplementation on the fractional synthetic rate (FSR) of muscle protein in 10 healthy, older men and 10 women (66.4 ± 4.5 y). We used 2H2O labeling to measure FSR of multiple muscle protein ontologies. D3-creatine dilution was used to determine muscle mass at baseline. Subjects ingested 70% 2H2O for 21 day and saliva samples were collected to determine body 2H2O enrichment. A microbiopsy was obtained from the m. vastus lateralis on Day 21. Subjects were randomly assigned to Fortetropin (19.8 g/d) or placebo (cheese powder, 19.8 g/d).
RESULTS
Restricting kinetic data to proteins with ≥2 peptides measured in at least 4 subjects per group resulted in 117 proteins meeting these criteria. The mean FSR for a majority of proteins in several muscle gene ontologies was higher in the Fortetropin group compared to placebo (32/38 myofibril proteins, 33/44 sarcoplasmic proteins, and 12/17 mitochondrial proteins) and this proportion was significantly different between groups using a binomial test and were independent of sex or baseline muscle mass.
CONCLUSIONS
The overall magnitude of the difference in muscle protein FSR of Fortetropin from placebo was 18%, with multiple gene ontologies affected. While these results should be confirmed in larger cohorts, they suggest that Fortetropin supplementation is effective for promoting muscle protein synthesis in older people.
Topics: Aged; Double-Blind Method; Female; Humans; Male; Middle Aged; Muscle Proteins; Proteolipids; Time Factors
PubMed: 32598445
DOI: 10.1093/gerona/glaa162 -
Current Biology : CB Nov 2020Cell vertices in epithelia comprise specialized tricellular junctions (TCJs) that seal the paracellular space between three adjoining cells [1, 2]. Although TCJs play...
Cell vertices in epithelia comprise specialized tricellular junctions (TCJs) that seal the paracellular space between three adjoining cells [1, 2]. Although TCJs play fundamental roles in tissue homeostasis, pathogen defense, and in sensing tension and cell shape [3-5], how they are assembled, maintained, and remodeled is poorly understood. In Drosophila, the transmembrane proteins Anakonda (Aka [6]) and Gliotactin (Gli [7]) are TCJ components essential for epithelial barrier formation. Additionally, the conserved four-transmembrane-domain protein M6, the only myelin proteolipid protein (PLP) family member in Drosophila, localizes to TCJs [8, 9]. PLPs associate with cholesterol-rich membrane domains and induce filopodia formation [10, 11] and membrane curvature [12], and Drosophila M6 acts as a tumor suppressor [8], but its role in TCJ formation remained unknown. Here, we show that M6 is essential for the assembly of tricellular, but not bicellular, occluding junctions, and for barrier function in embryonic epithelia. M6 and Aka localize to TCJs in a mutually dependent manner and are jointly required for TCJ localization of Gli, whereas Aka and M6 localize to TCJs independently of Gli. Aka acts instructively and is sufficient to direct M6 to cell vertices in the absence of septate junctions, while M6 is required permissively to maintain Aka at TCJs. Furthermore, M6 and Aka are mutually dependent for their accumulation in a low-mobility pool at TCJs. These findings suggest a hierarchical model for TCJ assembly, where Aka and M6 promote TCJ formation through synergistic interactions that demarcate a distinct plasma membrane microdomain at cell vertices.
Topics: Animals; Animals, Genetically Modified; Cell Membrane; Drosophila Proteins; Drosophila melanogaster; Embryo, Nonmammalian; Epithelial Cells; Female; Fluorescence Recovery After Photobleaching; Intravital Microscopy; Male; Membrane Proteins; Myelin Proteins; Myelin Proteolipid Protein; Nerve Tissue Proteins; Proteolipids; Receptors, Scavenger; Tight Junctions
PubMed: 32857972
DOI: 10.1016/j.cub.2020.08.003 -
Molecular Biology Reports Dec 2023The Proteolipid Protein 2 (PLP2), a protein in the Endoplasmic Reticulum (ER) membrane, has been reported to be highly expressed in various tumors. Previous studies have...
BACKGROUND
The Proteolipid Protein 2 (PLP2), a protein in the Endoplasmic Reticulum (ER) membrane, has been reported to be highly expressed in various tumors. Previous studies have demonstrated that the reduced PLP2 can induce apoptosis and autophagy through ER stress-related pathways, leading to a decreased proliferation and aggressiveness. However, there is no research literature on the role of PLP2 in Acute Myeloid Leukemia (AML).
METHODS
PLP2 expression, clinical data, genetic mutations, and karyotype changes from GEO, TCGA, and timer2.0 databases were analyzed through the R packages. The possible functions and pathways of cells were explored through GO, KEGG, and GSEA enrichment analysis using the clusterProfiler R package. Immuno-infiltration analysis was conducted using the Cibersort algorithm and the Xcell R package. RT-PCR and western blot techniques were employed to identify the PLP2 expression, examine the knockdown effects in THP-1 cells, and assess the expression of genes associated with endoplasmic reticulum stress and apoptosis. Flow cytometry was utilized to determine the apoptosis and survival rates of different groups.
RESULTS
PLP2 expression was observed in different subsets of AML and other cancers. Enrichment analyses revealed that PLP2 was involved in various tumor-related biological processes, primarily apoptosis and lysosomal functions. Additionally, PLP2 expression showed a strong association with immune cell infiltration, particularly monocytes. In vitro, the knockdown of PLP2 enhanced endoplasmic reticulum stress-related apoptosis and increased drug sensitivity in THP-1 cells.
CONCLUSIONS
PLP2 could be a novel therapeutic target in AML, in addition, PLP2 is a potential endoplasmic reticulum stress regulatory gene in AML.
Topics: Humans; Apoptosis; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Leukemia, Myeloid, Acute; Proteolipids
PubMed: 38085372
DOI: 10.1007/s11033-023-08994-1 -
The Journal of Heredity Jun 2018Antimicrobial peptides (AMPs) are a class of natural peptides with varying numbers of amino acids. They are principal components of innate immunity in vertebrates,...
Antimicrobial peptides (AMPs) are a class of natural peptides with varying numbers of amino acids. They are principal components of innate immunity in vertebrates, encoding natural antibiotics and providing a protective response against a broad range of microbes including those responsible for tuberculosis, an important disease in bison. NK-lysins are AMPs that have been described in various organisms and are coded by a single gene in several mammalian species, including human. Recently, we described a family of 4 NK-lysin genes in cattle. Here, we examined NK-lysin genes in bison and identified 4 bison paralogs (NK1, NK2A, NK2B, and NK2C), although the current bison genome assembly annotates only 2 (NK1 and NK2). Sequence and phylogenetic analysis support the triplication of NK2 prior to the most recent common ancestor of bison and cattle. Comparative mapping of bison and cattle paralogs indicates that the NK-lysin family is located on bison chromosome 11 with well-conserved synteny of flanking genes relative to cattle. The 3 bison NK-lysin2 genes share high sequence similarity with each other. RNA-seq analysis demonstrates that NK2A, NK2B, and NK2C are expressed primarily in the lung, whereas NK1 is expressed at low levels in all tissues studied. This tissue expression pattern differs from that previously reported for cattle, suggesting some divergence in function since the evolutionary separation of the 2 species.
Topics: Amino Acid Sequence; Animals; Bison; Chromosome Mapping; Gene Expression; Genome; Proteolipids; Sequence Homology, Amino Acid
PubMed: 29718298
DOI: 10.1093/jhered/esy022 -
Methods (San Diego, Calif.) Apr 2018Oriented sample solid-state NMR (OS-ssNMR) spectroscopy is uniquely suited to determine membrane protein topology at the atomic resolution in liquid crystalline bilayers...
Oriented sample solid-state NMR (OS-ssNMR) spectroscopy is uniquely suited to determine membrane protein topology at the atomic resolution in liquid crystalline bilayers under physiological temperature. However, the inherent low sensitivity of this technique has hindered the throughput of multidimensional experiments necessary for resonance assignments and structure determination. In this work, we show that doping membrane protein bicelle preparations with paramagnetic ion chelated lipids and exploiting paramagnetic relaxation effects it is possible to accelerate the acquisition of both 2D and 3D multidimensional experiments with significant saving in time. We demonstrate the efficacy of this method for a small membrane protein, sarcolipin, reconstituted in DMPC/POPC/DHPC oriented bicelles. In particular, using Cu-DMPE-DTPA as a dopant, we observed a decrease of H T of sarcolipin by 2/3, allowing us to reduce the recycle delay up to 3 times. We anticipate that these new developments will enable the routine acquisition of multidimensional OS-ssNMR experiments.
Topics: Animals; Humans; Membrane Proteins; Muscle Proteins; Nuclear Magnetic Resonance, Biomolecular; Protein Conformation; Proteolipids
PubMed: 29274874
DOI: 10.1016/j.ymeth.2017.12.017 -
Journal of Dental Research Nov 1980The purpose of this research was to examine the requirements for proteolipid initiation of calcification in culture. Proteolipid from a calcifiable microorganism,... (Comparative Study)
Comparative Study
The purpose of this research was to examine the requirements for proteolipid initiation of calcification in culture. Proteolipid from a calcifiable microorganism, Bacterionema matruchotii, was compared with proteolipid isolated from a non-calcifiable microorganism, Actinomyces naeslundii. Although A. naeslundii does not calcify in culture, lyophilized cells and proteolipid-containing extracts do initiate apatite formation. A. naeslundii proteolipid (ANN) differs from B. matruchotii (BMN) in concentration, apoprotein polarity, and phospholipid composition. These differences may alter the ability of ANN to nucleate apatite in the intact cell.
Topics: Actinomyces; Actinomycetaceae; Apatites; Calcification, Physiologic; Phospholipids; Proteolipids
PubMed: 6933191
DOI: 10.1177/00220345800590111801 -
American Journal of Respiratory Cell... Feb 1991Exposure of adult rats to 85% ambient oxygen increased the content of surfactant proteins SP-A, SP-B, and SP-C recovered from alveolar lavage. The surfactant proteins...
Exposure of adult rats to 85% ambient oxygen increased the content of surfactant proteins SP-A, SP-B, and SP-C recovered from alveolar lavage. The surfactant proteins increased during 1 to 7 d of oxygen exposure. The increased surfactant protein was associated with increased relative abundance of mRNA encoding each of the proteins in lung tissue. Exposure to hyperoxia progressively increased the amounts of the surfactant proteins in alveolar lavage fluid as estimated by immunoblot analysis after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The mRNAs encoding SP-A (1.7 and 1.0 kb), SP-B (1.6 kb), and SP-C (0.9 kb) increased significantly after oxygen exposure for 5 d. The present findings support the concept that oxygen exposure mediates surfactant protein expression at a pretranslational level.
Topics: Animals; Blotting, Northern; Blotting, Western; Bronchoalveolar Lavage Fluid; Cattle; Densitometry; Male; Oxygen; Proteolipids; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants; RNA, Messenger; Rats; Rats, Inbred Strains
PubMed: 1991071
DOI: 10.1165/ajrcmb/4.2.102 -
Analytical Chemistry Jul 2012We have developed a microfluidic flow cell where stepwise enzymatic digestion is performed on immobilized proteoliposomes and the resulting cleaved peptides are analyzed...
We have developed a microfluidic flow cell where stepwise enzymatic digestion is performed on immobilized proteoliposomes and the resulting cleaved peptides are analyzed with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The flow cell channels consist of two parallel gold surfaces mounted face to face with a thin spacer and feature an inlet and an outlet port. Proteoliposomes (50-150 nm in diameter) obtained from red blood cells (RBC), or Chinese hamster ovary (CHO) cells, were immobilized on the inside of the flow cell channel, thus forming a stationary phase of proteoliposomes. The rate of proteoliposome immobilization was determined using a quartz crystal microbalance with dissipation monitoring (QCM-D) which showed that 95% of the proteoliposomes bind within 5 min. The flow cell was found to bind a maximum of 1 μg proteoliposomes/cm(2), and a minimum proteoliposome concentration required for saturation of the flow cell was determined to be 500 μg/mL. Atomic force microscopy (AFM) studies showed an even distribution of immobilized proteoliposomes on the surface. The liquid encapsulated between the surfaces has a large surface-to-volume ratio, providing rapid material transfer rates between the liquid phase and the stationary phase. We characterized the hydrodynamic properties of the flow cell, and the force acting on the proteoliposomes during flow cell operation was estimated to be in the range of 0.1-1 pN, too small to cause any proteoliposome deformation or rupture. A sequential proteolytic protocol, repeatedly exposing proteoliposomes to a digestive enzyme, trypsin, was developed and compared with a single-digest protocol. The sequential protocol was found to detect ~65% more unique membrane-associated protein (p < 0.001, n = 6) based on peptide analysis with LC-MS/MS, compared to a single-digest protocol. Thus, the flow cell described herein is a suitable tool for shotgun proteomics on proteoliposomes, enabling more detailed characterization of complex protein samples.
Topics: Animals; CHO Cells; Chromatography, Liquid; Collagenases; Cricetinae; Equipment Design; Erythrocytes; Humans; Hydrodynamics; Immobilized Proteins; Microfluidic Analytical Techniques; Peptide Hydrolases; Peptides; Proteolipids; Tandem Mass Spectrometry
PubMed: 22656064
DOI: 10.1021/ac300519q -
Microscopy Research and Technique Mar 2001During myelin formation, membrane-associated proteins have to be sorted and transported in specified membrane regions such as compact and non-compact myelin membranes....
During myelin formation, membrane-associated proteins have to be sorted and transported in specified membrane regions such as compact and non-compact myelin membranes. One protein that may be involved in such a process is the Myelin and Lymphocyte protein MAL (VIP17/ MVP17). MAL was identified as a novel myelin membrane component expressed by oligodendrocytes and Schwann cells. Since MAL has been shown to be important in the apical sorting machinery of polarized cells, we have started to investigate the possible functional role of MAL in sorting myelin membrane-associated molecules. In this study, we have generated cDNA constructs with green fluorescent protein (GFP) either at the N- or C-terminus of MAL. Transfection experiments showed that GFP-MAL expression resembles that of normal MAL, whereas the MAL-GFP fusion construct was not properly transported within the cell. Furthermore, we could demonstrate that GFP-MAL is enriched in detergent insoluble glycolipid-enriched microdomains as already seen for untagged MAL. As a prerequisite for the generation of transgenic mice expressing GFP-MAL under the control of its own regulatory elements, we have generated a cDNA construct with an 8-kb MAL promotor fragment fused to GFP-MAL. Transfection experiments of the Oli-neu oligodendrocyte cell line showed that GFP-MAL was expressed, but only in cells, which were stimulated for differentiation with cAMP. In summary, the results confirm that the fusion protein GFP-MAL is incorporated into detergent-insoluble complexes and the 8-kb MAL promotor fragment is sufficient to be activated in oligodendrocytes.
Topics: Animals; COS Cells; Cell Line; Chlorocebus aethiops; Fluorescent Antibody Technique; Green Fluorescent Proteins; Luminescent Proteins; Membrane Microdomains; Membrane Transport Proteins; Myelin Proteins; Myelin and Lymphocyte-Associated Proteolipid Proteins; Oligodendroglia; Proteolipids; Rats; Recombinant Fusion Proteins
PubMed: 11276117
DOI: 10.1002/jemt.1049