A cellular chemical probe targeting the chromodomains of Polycomb repressive complex 1

We report the design and characterization of UNC3866, a potent antagonist of the methyllysine (Kme) reading function of the Polycomb CBX and CDY families of chromodomains. Polycomb CBX proteins regulate gene expression by targeting Polycomb repressive complex 1 (PRC1) to sites of H3K27me3 via their chromodomains. UNC3866 binds the chromodomains of CBX4 and CBX7 most potently, with a K d of â ∼1/4100 nM for each, and is 6-to 18-fold selective as compared to seven other CBX and CDY chromodomains while being highly selective over >250 other protein targets. X-ray crystallography revealed that UNC3866's interactions with the CBX chromodomains closely mimic those of the methylated H3 tail. UNC4195, a biotinylated derivative of UNC3866, was used to demonstrate that UNC3866 engages intact PRC1 and that EED incorporation into PRC1 is isoform dependent in PC3 prostate cancer cells. Finally, UNC3866 inhibits PC3 cell proliferation, consistent with the known ability of CBX7 overexpression to confer a growth advantage, whereas UNC4219, a methylated negative control compound, has negligible effects

Erratum: Addendum: A cellular chemical probe targeting the chromodomains of Polycomb repressive complex 1 (Nature chemical biology (2016) 12 3 (180-187))

[No abstract available

Lysine methylation-dependent binding of 53BP1 to the pRb tumor suppressor.

The retinoblastoma tumor suppressor protein pRb is a key regulator of cell cycle progression and mediator of the DNA damage response. Lysine methylation at K810, which occurs within a critical Cdk phosphorylation motif, holds pRb in the hypophosphorylated growth-suppressing state. We show here that methyl K810 is read by the tandem tudor domain containing tumor protein p53 binding protein 1 (53BP1). Structural elucidation of 53BP1 in complex with a methylated K810 pRb peptide emphasized the role of the 53BP1 tandem tudor domain in recognition of the methylated lysine and surrounding residues. Significantly, binding of 53BP1 to methyl K810 occurs on E2 promoter binding factor target genes and allows pRb activity to be effectively integrated with the DNA damage response. Our results widen the repertoire of cellular targets for 53BP1 and suggest a previously unidentified role for 53BP1 in regulating pRb tumor suppressor activity

Lysine methylation-dependent binding of 53BP1 to the pRb tumor suppressor.

The retinoblastoma tumor suppressor protein pRb is a key regulator of cell cycle progression and mediator of the DNA damage response. Lysine methylation at K810, which occurs within a critical Cdk phosphorylation motif, holds pRb in the hypophosphorylated growth-suppressing state. We show here that methyl K810 is read by the tandem tudor domain containing tumor protein p53 binding protein 1 (53BP1). Structural elucidation of 53BP1 in complex with a methylated K810 pRb peptide emphasized the role of the 53BP1 tandem tudor domain in recognition of the methylated lysine and surrounding residues. Significantly, binding of 53BP1 to methyl K810 occurs on E2 promoter binding factor target genes and allows pRb activity to be effectively integrated with the DNA damage response. Our results widen the repertoire of cellular targets for 53BP1 and suggest a previously unidentified role for 53BP1 in regulating pRb tumor suppressor activity

Mineral Availability and Dietary Fiber Characteristics of Moringa oleifera

Abstract Background: There is an increasing awareness on the potential of Moringa Oleifera (Malunggay) as a high-value agricultural crop because of its high dietary fiber and nutrient contents. Objective: The study determined mineral availability and dietary fiber characteristics of Moringa Oleifera. Materials and Methods: Malunggay leaves and fruit from Metro Manila and two suppliers were analyzed. Proximate composition, minerals, phytic/tannic acid, total/soluble/insoluble fiber were analysed and subjected for mineral availability and dietary fiber fermentation in vitro. Results: All samples were good sources of protein (46.4 g/100g), ash (11.5 g/100 g) and beta-carotene (45172 µg/100g). Mineral content of malunggay leaves powder were: calcium (1.3±0.1-2.0± 0.0 g/100g) > iron (5.7±0.2-7.8± 0.0mg/100g) > zinc (3.4±0.1-4.8±0.0 mg/100g; P<0.05). The fruit powder contained 4.1±0.1 mg iron, 3.2±0.0 mg zinc and 0.4±0.0 g calcium per 100 g. Phytic acid (368±06 -576±72 mg/100 g sample) and tannic acid (1280±24-1956±09 mg/100 g) from leaves and fruits were high. All products were good sources of total (24.3±0.2-39.9±0.2 g/100g), insoluble (19.6±0.2-34.9±0.2 g/100g) and soluble (3.1±0.2-5.0±0.2 g/100g) dietary fiber. Zinc availability (59.5±0.1-93.8±0.1%) from malunggay leaves was significantly greater than that of calcium (25.0±0.1-53.8± 0.2%) and iron (7.0±0.1-19.5±0.1%; (P<0.05). Similar trend was observed from malunggay fruit. Dietary fiber fermentation of malunggay leaves produced short chain fatty acids, propionate (161.8±5.0-210.7±13.1 mg/g) > acetate (1.4±0.1 -21.7±0.1 mg/g) > butyrate (3.0±0.1-7.7±2.3 mg/g; P<0.05). Conclusions: Malunggay leaves and fruits are good sources of iron, zinc and calcium and moderate to highly available for absorption regardless of the high content of phytic and tannic acid. Malunggay leaves are excellent sources of dietary fiber, fermentable and produce short chain fatty acids with greater amounts of propionate shown to inhibit cholesterol synthesis

Iron Bioavailability from Ferrous Ammonium Phosphate, Ferrous Sulfate, and Ferric Pyrophosphate in an Instant Milk Drink—A Stable Isotope Study in Children

Ferrous ammonium phosphate (FAP) is an iron salt that has been developed for the fortification of food matrices sensitive to color and flavor changes. The objective of the study was to measure iron absorption from FAP in young children and compare it to a previous evaluation of FAP in young women. A double-blind randomized crossover study with two parallel arms was used to evaluate the iron absorption from FAP added to reconstituted milk powder in comparison to that from ferrous sulfate (FeSO4 ) and ferric pyrophosphate (FePP). Iron absorption was measured in 39 children aged 3-to 6-years-old using erythrocyte incorporation of stable Fe isotopes (57Fe,58Fe). The geometric mean iron absorption in iron replete children from FAP, FeSO4 and FePP from milk was 8.3%, 7.6% and 2.1%, respectively. Iron absorption from FAP and FeSO4 fortified milk was not significantly different (p = 0.199); however, it was significantly higher than from FePP fortified milk (p < 0.001). Iron bioavailability from FAP and FePP relative to FeSO4 (relative bioavailability (RBV)) was 110% and 33%, respectively. The RBV of FAP (110%) in iron replete children was higher than previously reported RBV (71%) in mainly iron deficient women. The difference in iron status between the children and women in the respective studies may explain the different RBV values and is discussed.ISSN:2072-664

Forensic DNA evidence and the death penalty in the Philippines

The death penalty remains a contentious issue even though it has been abolished in countries such as Australia, New Zealand, Canada, European Union member nations and some Asian countries such as Cambodia, East Timor and Nepal. Many argue that the irrevocability of the death penalty, in the face of potential erroneous convictions, can never justify its imposition. The Philippines, the first Asian country that abolished the death penalty in 1987, held the record for the most number of mandatory death offenses (30 offenses) and death eligible offenses (22 offenses) after it was re-imposed in 1994. Majority of death penalty convictions were decided based on testimonial evidence. While such cases undergo automatic review by the Supreme Court, the appellate process in the Philippines is not structured to accept post-conviction evidence, including DNA evidence. Because of the compelling nature of post-conviction DNA evidence in overturning death penalty convictions in the United States, different groups advocated its use in the Philippines. In one such case, People v Reynaldo de Villa, the defendant was charged with raping his 13-year-old niece that supposedly led to birth of a female child, a situation commonly known as \u27criminal paternity\u27. This paper reports the results of the first post-conviction DNA test using 16 Short Tandem Repeat (STR) DNA markers in a criminal paternity case (People v Reynaldo de Villa) and discusses the implications of these results in the Philippine criminal justice system

Arginine methylation-dependent reader-writer interplay governs growth control by E2F-1

The mechanisms that underlie and dictate the different biological outcomes of E2F-1 activity have yet to be elucidated. We describe the residue-specific methylation of E2F-1 by the asymmetric dimethylating protein arginine methyltransferase 1 (PRMT1) and symmetric dimethylating PRMT5 and relate the marks to different functional consequences of E2F-1 activity. Methylation by PRMT1 hinders methylation by PRMT5, which augments E2F-1-dependent apoptosis, whereas PRMT5-dependent methylation favors proliferation by antagonizing methylation by PRMT1. The ability of E2F-1 to prompt apoptosis in DNA damaged cells coincides with enhanced PRMT1 methylation. In contrast, cyclin A binding to E2F-1 impedes PRMT1 methylation and augments PRMT5 methylation, thus ensuring that E2F-1 is locked into its cell-cycle progression mode. The Tudor domain protein p100-TSN reads the symmetric methylation mark, and binding of p100-TSN downregulates E2F-1 apoptotic activity. Our results define an exquisite level of precision in the reader-writer interplay that governs the biological outcome of E2F-1 activity. © 2013 Elsevier Inc