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Apr 2020 DOI 10.14302/issn.2832-4048.jsm-20-3211
Papaconstantinou JohnCorresponding author
The Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston Texas 77555-0643
Aging mammalian skeletal muscle satellite cells (MuSCs) undergo a decline of stem cell/progenitor cell proliferative and regenerative capacity, and the development of a physiological milieu characteristic of a state of chronic sterile inflammation. p38αMAPK and ERK1/2 are two major signaling pathways that regulate the age-associated decline of MuSC proliferative capacity. In this review we propose the following mechanism that links the p38αMAPK pathway to the decline of self-renewal and regenerative capacity of aged MuSCs: a) the HS-FGF-2-FGFR1-p38αMAPK-Axis, a tightly linked homeostatic signaling complex, is in synchrony with the autoinhibition of FGFR1; b) autoinhibition contributes to the Axis’ regulation of the homeostasis of P-p38αMAPK activity in juvenile MuSC; c) this combination of protein-protein interactions is characteristic of a juvenile cytoplasmic milieu of beneficial P-p38αMAPK activity and d) includes Sprouty1 inhibition that supports the stimulation of FGF-2 --> miR-29a; e) the miR29a dismantles the basement membrane in preparation for the initiation of replication; f) an age-associated impaired, dysregulated, over-sulfated heparan sulfate ligand (HS)-FGF-2 fails to activate FGFR1 in aged MuSCs; g) this uncouples its regulation of p38αMAPK and ERK1/2 pathways and results in desensitization of FGFR1; h) desensitization of FGFR1 and Sprouty1 interaction in aged MuSC uncouples their regulation of P-p38αMAPK in the aged MuSCs; i) this enables a state of chronic sterile inflammation to promote and sustain an increased level of P-p38αMAPK activity; and, j) the increased activity of P-p38αMAPK in aged MuSC stimulates the production of cell cycle inhibitors, miR-1 and miR-133, thereby attenuating the expression of the cell cycle regulators, SP1 and cyclin D1, resulting in a G1/S arrest; j) the increased level of p38αMAPK activity promotes the apoptosis of the aged activated MuSCs. This mechanism involves the synergistic interactions of HS-FGF2-FGFR-1, Sprouty (spry1), miR-1, miR-133 and miR-29a that unify the extracellular niche and intracellular milieu for the juvenile vs age-associated regulation of proliferative capacity of the MuSC. Our hypothesis unifies these interactions with the role of the extracellular niche and intracellular milieu in the stimulation of juvenile proliferation vs age-associated decline of skeletal muscle satellite cell self-renewal and regenerative proliferation. Word Count = 344
Jan 2019 DOI 10.14302/issn.2643-0282.imsj-18-2448
Santiago Freitas e Silva KleberCorresponding author
Biological Sciences Institute, Federal University of Goiás, Brazil
Fungal infections increased substantially in the last years, becoming a relevant public health problem. Many of these infections account for high rates of morbidity and mortality. The emergence of resistant fungal clinical isolates have also motivate studies to find new antifungal therapies. Candida albicans is an oportunistic pathogen and affects a great number of immunocompromised patients worldwide. The marine ecosystem has been considered a rich source of bioactive metabolites due to the complexity and originality of its structures. Proteins and peptides from marine organisms have been shown to have antiviral, anti-inflammatory, antimalarial, anticancer, antimicrobial and antifungal properties. Arenicins are antimicrobial peptides isolated from the marine lugworm Arenicola marina with 21 amino acid residues in a β-hairpin structure. Dihydrofolate reductase, exo-b-(1,3)-glucanase and sterol 14α-demethylase are essential C. albincas enzymes that take part in DNA, cell wall and membrane metabolism, respectively. The present study evaluates the interaction of arenicin with important enzymes of C. albicans related to cell wall, ergosterol and DNA metabolism in order to elucidate possible molecular targets. We showed through an in silico approach, that a single compound from a marine worm (A. marina), can bind to three C. albicans essential proteins. The interaction occurs in regions inside the active site or at least near, with amino acid residues evaluated as hot spots. Arenicin is a new promising antifugal drug. The next step is to investigate protein-protein interactions performed by DHFR, EBG and CYP51 and assess whether arenicin is able to disrupt essential interaction or not.
Dec 2012 DOI 10.14302/issn.2326-0793.jpgr-12-100
Li ShitaoCorresponding author
Department of Microbiology & Immunobiology, Harvard Medical School, Boston, Massachusetts, 02115, USA.
Defining protein-protein interactions is essential for understanding the mechanisms by which cells regulate basic functions, such as metabolism, transcription, and signal transduction. Affinity purification followed by tandem mass spectrometry (AP-MS) has application for discovery of new interactors regulating various cellular processes. Here we optimize the purification method for AP-MS and develop a simplified unbiased analytical tool, Z-score plus prey occurrence and reproducibility (ZSPORE) for data analysis. Using this pipeline we achieve a higher efficiency of AP-MS and enhanced identification of high confidence interacting proteins (HCIP) in mammalian cells. When applied to analysis of the innate immune interactome, these methods enhanced HCIP identification. In addition, we investigated the GRB2 complex, which is associated with signal transduction and cell growth. Twenty-four known GRB2 interacting proteins were identified plus 26 new GRB2 binding partners. Thus, these straightforward methods recapitulate known protein interactions, discover novel complexes, and allow mapping of protein interaction networks.