ULK2 Ser 1027 Phosphorylation by PKA Regulates Its Nuclear Localization Occurring through Karyopherin Beta 2 Recognition of a PY-NLS Motif

Uncoordinated 51-like kinase 2 (ULK2), a member of the serine/threonine kinase family, plays an essential role in the regulation of autophagy in mammalian cells. Given the role of autophagy in normal cellular homeostasis and in multiple diseases, improved mechanistic insight into this process may result in the development of novel therapeutic approaches. Here, we present evidence that ULK2 associates with karyopherin beta 2 (Kapβ2) for its transportation into the nucleus. We identify a potential PY-NLS motif (⁷⁷⁴gpgfgssppGaeaapslRyvPY⁷⁹⁵) in the S/P space domain of ULK2, which is similar to the consensus PY-NLS motif (R/K/H)X _2–5PY. Using a pull-down approach, we observe that ULK2 interacts physically with Kapβ2 both in vitro and in vivo. Confocal microscopy confirmed the co-localization of ULK2 and Kapβ2. Localization of ULK2 to the nuclear region was disrupted by mutations in the putative Kapβ2-binding motif (P794A). Furthermore, in transient transfection assays, the presence of the Kapβ2 binding site mutant (the cytoplasmic localization form) was associated with a substantial increase in autophagy activity (but a decrease in the in vitro serine-phosphorylation) compared with the wild type ULK2. Mutational analysis showed that the phosphorylation on the Ser1027 residue of ULK2 by Protein Kinase A (PKA) is the regulatory point for its functional dissociation from Atg13 and FIP 200, nuclear localization, and autophagy. Taken together, our observations indicate that Kapβ2 interacts with ULK2 through ULK2’s putative PY-NLS motif, and facilitates transport from the cytoplasm to the nucleus, depending on its Ser1027 residue phosphorylation by PKA, thereby reducing autophagic activity.     

Differential Expression of Programmed Cell Death on the Follicular Development in Normal and Miniature Pig Ovary

Follicles are important in oocyte maturation. Successful estrous cycle requires remodeling of follicular cells, and proper execution of programmed cell death is crucial for normal follicular development. The objectives of the present study were to understand programmed cell death during follicle development, to analyze the differential follicle development patterns, and to assess the patterns of apoptosis and autophagy expression during follicle development in normal and miniature pigs. Through the analysis of differential patterns of programmed cell death during follicular development in porcine, MAP1LC3A, B and other autophagy-associated genes (ATG5, mTOR, Beclin-1) were found to increase in normal pigs, while it decreased in miniature pigs. However, for the apoptosis-associated genes, progression of genes during follicular development increased in miniature pigs, while it decreased in normal pigs. Thus, results show that normal and miniature pigs showed distinct patterns of follicular remodeling manifesting that programmed cell death largely depends on the types of pathway during follicular development (Type II or autophagy for normal pigs and Type I or apoptosis for miniature pigs).     

Natural,semisynthetic and synthetic tyrosinase inhibitors

Tyrosinase plays a pivotal role in the synthesis of melanin pigment synthesis on skin utilizing tyrosine as a substrate. Melanin is responsible for the protection against harmful ultraviolet irradiation, which can cause significant pathological conditions, such as skin cancers. However, it can also create esthetic problems when accumulated as hyperpigmented spots. Various skin-whitening ingredients which inhibit tyrosinase activity have been identified. Some of them, especially ones with natural product origins, possess phenolic moiety and have been employed in cosmetic products. Semi-synthetic and synthetic inhibitors have also been developed under inspiration of the natural inhibitors yet some of which have no phenolic groups. In this review, tyrosinase inhibitors with natural, semi-synthetic and synthetic origins are listed up with their structures, activities and characteristics. Further, a recent report on the adverse effect of a natural melanin synthesis inhibitor which was included in skin-whitening cosmetics is also briefly discussed.     

Orthogonal arrays are absent from the membranes of human glioblastomatous tissues

Human astrocytic gliomas were studied with the freeze fracture technique. Orthogonal arrays of particles were noted in the plasma membranes of low-grade astrocytoma tissues. However, no such arrays were found in the plasma membranes of anaplastic glioma or glioblastoma tissues. Gap junctions were rarely seen in the membranes of these higher-grade gliomas; when seen, they consisted of relatively few particles in poorly organized plaques. These plasma membranes were dominated by randomly distributed single particles. These findings constitute aspects of the loss of differentiation in these malignant tumors.     

Molecular Dynamics Simulation Studies of Zeolite-A. IV. Structure and Dynamics of NH4 + ions in a Rigid Dehydrated Zeolite-A

Abstract

In recent papers [1–3] we reported molecular dynamics simulation studies of ions and water molecules adsorbed in a rigid zeolite-A framework using a simple Lennard-Jones potential plus Coulomb potential with Ewald summation to investigate the structure and dynamics of the adsorbates. In the present paper the same technique is applied to study the local structure and dynamics of NH₄ ⁺ ions in a rigid dehydrated zeolite-A. During the preliminary equilibration, the unstable NH₄(4) type ion (the 12th ion) is pushed down to near a more stable 6-ring position in the α-cage that is already associated with an NH₄(1) type ion (the 1st) in the β-cage, which moves to another 6-ring position in the β-cage that is already associated with an NH₄(2) type ion (the 7th) in the α-cage. Calculated x, y, and z coordinates of some NH₄ ⁺ ions are in good agreement with those obtained from an X-ray diffraction experiment except that no NH₄(4) type ion is found and there are six NH₄(2) type ions instead of 0.5 and 5.5 occupancy. The analyses of calculated interatomic distances and time correlation functions of these ions indicate that the NH₄(1 – 1) and NH₄(3) type ions are associated loosely with only one O (3) atom of the 6-ring and with only one O (1) atom of the 8-ring windows, respectively, while the NH₄(1–2) and NH₄(2) type ions are associated strongly with two or three O (3) atoms of the 6-ring windows in the α- and β-cages, respectively. The analysis of hydrogen bond time correlation functions of these ions indicate that about one, two or three, three, and one hydrogen bond of each NH₄(1–1), NH₄(1–2), NH₄(2) and NH₄(3) type ion is kept for 1.4, 21, 75, and 1.4 ps, respectively, before breakup of the hydrogen bond occurs and significant exchange of O atom hydrogen-bonded to the ion.     

Extraction behavior of caffeine and EGCG from green and black tea

A dipping method was developed to extract the catechins (EGCG) and alkaloids (caffeine) from green tea (Korea) and black tea (Sri Lanka). The effects of the solvent composition (water vs. ethanol), extraction time, temperatures, and solvent pH on the amount of catechins (EGCG) and alkaloids (caffeine) extracted from green and black tea were investigated. Reversedphase high-performance liquid chromatography (RP-HPLC) was used to analyze the catechins (EGCG) and alkaloids (caffeine) extracted. The content of EGCG and caffeine in green tea extracts was in the range of 2.04∼0.30 and 10.22∼0.85 mg/g, respectively. The amount of EGCG and caffeine in black tea extracts was in the range of 0.32∼0.24 and 5.26∼1.01 mg/g, respectively. The amount of caffeine extracted from green and black tea was greater than the amount of EGCG. Pure water is the best solvent for extracting EGCG and caffeine from green tea. The amount of caffeine extracted from green and black tea increased as the temperature, extraction time, and hydrogen ion concentration of the solvent increased. Although the amount of EGCG extracted from green tea increased as the temperature increased, the amount of EGCG extracted from black tea was not affected by temperature. The extraction of EGCG from both green and black tea was not affected by the hydrogen ion concentration of the solvent.