Receptor for advanced glycation end products is subjected to protein ectodomain shedding by metalloproteinases

The receptor for advanced glycation end products (RAGE) is a 55-kDa type I membrane glycoprotein of the immunoglobulin superfamily. Ligand-induced up-regulation of RAGE is involved in various pathophysiological processes, including late diabetic complications and Alzheimer disease. Application of recombinant soluble RAGE has been shown to block RAGE-mediated pathophysiological conditions. After expression of full-length RAGE in HEK cells we identified a 48-kDa soluble RAGE form (sRAGE) in the culture medium. This variant of RAGE is smaller than a 51-kDa soluble version derived from alternative splicing. The release of sRAGE can be induced by the phorbol ester PMA and the calcium ionophore calcimycin via calcium-dependent protein kinase C subtypes. Hydroxamic acid-based metalloproteinase inhibitors block the release of sRAGE, and by RNA interference experiments we identified ADAM10 and MMP9 to be involved in RAGE shedding. In protein biotinylation experiments we show that membrane-anchored full-length RAGE is the precursor of sRAGE and that sRAGE is efficiently released from the cell surface. We identified cleavage of RAGE to occur close to the cell membrane. Ectodomain shedding of RAGE simultaneously generates sRAGE and a membrane-anchored C-terminal RAGE fragment (RAGE-CTF). The amount of RAGE-CTF increases when RAGE-expressing cells are treated with a gamma-secretase inhibitor, suggesting that RAGE-CTF is normally further processed by gamma-secretase. Identification of these novel mechanisms involved in regulating the availability of cell surface-located RAGE and its soluble ectodomain may influence further research in RAGE-mediated processes in cell biology and pathophysiology.     

Lats2/Kpm is required for embryonic development, proliferation control and genomic integrity

The Drosophila melanogaster warts/lats tumour suppressor has two mammalian counterparts LATS1/Warts-1 and LATS2/Kpm. Here, we show that mammalian Lats orthologues exhibit distinct expression profiles according to germ cell layer origin. Lats2(-/-) embryos show overgrowth in restricted tissues of mesodermal lineage; however, lethality ultimately ensues on or before embryonic day 12.5 preceded by defective proliferation. Lats2(-/-) mouse embryonic fibroblasts (MEFs) acquire growth advantages and display a profound defect in contact inhibition of growth, yet exhibit defective cytokinesis. Lats2(-/-) embryos and MEFs display centrosome amplification and genomic instability. Lats2 localizes to centrosomes and overexpression of Lats2 suppresses centrosome overduplication induced in wild-type MEFs and reverses centrosome amplification inherent in Lats2(-/-) MEFs. These findings indicate an essential role of Lats2 in the integrity of processes that govern centrosome duplication, maintenance of mitotic fidelity and genomic stability.     

Synthesis and pharmacological assessment of derivatives of isoxazolo[4,5-d]pyrimidine

A series of new 5-alkyl and 5-arylisoxazolo[4,5-d]pyrimidinones (5a-g, 6-8) were prepared from 4-amino-3-oxo-isoxazolidine-5-carboxylic acid amide. Some of the aryl derivatives of isoxazolo[4,5-d]pyrimidine were tested pharmacologically in comparison with Diazepam. Compounds 5b-d and 7 demonstrated interesting anxiolytic activity.     

ADAM and ADAMTS family proteins and their role in the colorectal cancer etiopathogenesis

The ADAM and ADAMTS families, also called adamalysins belong to an important group of extracellular matrix proteins. The ADAMs family belong to both the transmembrane and secreted proteins, while ADAMTS family only contains secreted forms. Adamalysins play an important role in the cell phenotype regulation via their activities in signaling pathways, cell adhesion and migration. The human proteome contains 21 ADAM, and 19 ADAMTS proteins, which are involved in extracellular matrix remodeling, shedding of various substrates such as: adhesion ligands, growth factors, their receptors and diverse cytokines. Recent studies provide evidence that adamalysins play a crucial role in colorectal cancer (CRC) etiopathogenesis. It seems possible that adamalysins might be used as CRC prediction markers or potential pharmaceutical targets. [BMB Reports 2013; 46(3): 139-150]     

Mitochondrial protein import in plants – Signals,Sorting, Targeting,Processing and Regulation

Plant Molecular Biology - Mitochondrial biogenesis requires a coordinated expression of both the nuclear and the organellar genomes and specific intracellular protein trafficking, processing and...     

Activation of DNA-PK by Ionizing Radiation Is Mediated by Protein Phosphatase 6

DNA-dependent protein kinase (DNA-PK) plays a critical role in DNA damage repair, especially in non-homologous end-joining repair of double-strand breaks such as those formed by ionizing radiation (IR) in the course of radiation therapy. Regulation of DNA-PK involves multisite phosphorylation but this is incompletely understood and little is known about protein phosphatases relative to DNA-PK. Mass spectrometry analysis revealed that DNA-PK interacts with the protein phosphatase-6 (PP6) SAPS subunit PP6R1. PP6 is a heterotrimeric enzyme that consists of a catalytic subunit, plus one of three PP6 SAPS regulatory subunits and one of three ankyrin repeat subunits. Endogenous PP6R1 co-immunoprecipitated DNA-PK, and IR enhanced the amount of complex and promoted its import into the nucleus. In addition, siRNA knockdown of either PP6R1 or PP6 significantly decreased IR activation of DNA-PK, suggesting that PP6 activates DNA-PK by association and dephosphorylation. Knockdown of other phosphatases PP5 or PP1γ1 and subunits PP6R3 or ARS-A did not reduce IR activation of DNA-PK, demonstrating specificity for PP6R1. Finally, siRNA knockdown of PP6R1 or PP6 but not other phosphatases increased the sensitivity of glioblastoma cells to radiation-induced cell death to a level similar to DNA-PK deficient cells. Our data demonstrate that PP6 associates with and activates DNA-PK in response to ionizing radiation. Therefore, the PP6/PP6R1 phosphatase is a potential molecular target for radiation sensitization by chemical inhibition.     

The monoclonal antibody combination REGEN-COV protects against SARS-CoV-2 mutational escape in preclinical and human studies

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Identifying critical migratory bottlenecks and high‐use areas for an endangered migratory soaring bird across three continents

Migrant birds face a number of threats throughout their annual cycle, including persecution, collision with energy infrastructure, and habitat and climate change. A key challenge for the conservation of migrants is the identification of important habitat, including migratory concentration areas, because species survival rates may be determined by events in geographically very limited areas. Remote‐tracking technology is facilitating the identification of such critical habitat, although the strategic identification of important sites and incorporation of such knowledge in conservation planning remains limited. We tracked 45 individuals of an endangered, soaring migrant (Egyptian vulture Neophron percnopterus), over 75 complete migrations that traversed three continents along the Red Sea Flyway. We summarize and contextualize migration statistics by season and age class, including migration start, midpoint, and end dates, as well as linear and cumulative migration distance, migration duration and speed, and route straightness. Then, using dynamic Brownian bridge movement models, we quantified space use to identify the most important migratory bottlenecks and high‐use areas on the flyway. These areas each accounted for < 5% of the overall movement range of the tracked birds, yet > 20% of all tracks passed through bottlenecks, and > 50% of the overall vulture time spent on migration fell within high‐use areas. The most important sites were located at the southeastern Red Sea coast and Bab‐el‐Mandeb Strait (Saudi Arabia, Yemen, Djibouti), the Suez Canal zone (Egypt), and the Gulf of Iskenderun (Turkey). Discouragingly however, none of the area within the major migratory bottlenecks was protected and < 13% of the high‐use areas were protected. This demonstrates a very concerning gap in the protected area network for migratory soaring birds along the Red Sea Flyway. Because reducing threats at migratory concentrations can be a very efficient approach to protect populations, our work provides clear guidelines where conservation investment is urgently needed to benefit as many as 35 migratory soaring‐bird species that regularly use the Red Sea Flyway.