Human seven-ß-strand (METTL) methyltransferases - conquering the universe of protein lysine methylation.

Lysine methylation is an abundant posttranslational modification, which has been most intensively studied in the context of histone proteins, where it represents an important epigenetic mark. Lysine methylation of histone proteins is primarily catalyzed by SET-domain methyltransferases (MTases). However, it has recently become evident that also another MTase family, the so-called seven-ß-strand (7BS) MTases, often denoted METTLs (methyltransferase-like), contains several lysine (K)-specific MTases (KMTs). These enzymes catalyze the attachment of up to three methyl groups to lysine residues in specific substrate proteins, using S-adenosylmethionine (AdoMet) as methyl donor. About a decade ago, only a single human 7BS KMT was known, namely the histone-specific DOT1L, but 15 additional 7BS KMTs have now been discovered and characterized. These KMTs typically target a single nonhistone substrate that, in most cases, belongs to one of the following three protein groups: components of the cellular protein synthesis machinery, mitochondrial proteins, and molecular chaperones. This article provides an extensive overview and discussion of the human 7BS KMTs and their biochemical and biological roles.

A cell competition-based small molecule screen identifies a novel compound that induces dual c-Myc depletion and p53 activation.

Breakpoint Cluster Region-Abelson kinase (BCR-Abl) is a driver oncogene that causes chronic myeloid leukemia and a subset of acute lymphoid leukemias. Although tyrosine kinase inhibitors provide an effective treatment for these diseases, they generally do not kill leukemic stem cells (LSCs), the cancer-initiating cells that compete with normal hematopoietic stem cells for the bone marrow niche. New strategies to target cancers driven by BCR-Abl are therefore urgently needed. We performed a small molecule screen based on competition between isogenic untransformed cells and BCR-Abl-transformed cells and identified several compounds that selectively impair the fitness of BCR-Abl-transformed cells. Interestingly, systems-level analysis of one of these novel compounds, DJ34, revealed that it induced depletion of c-Myc and activation of p53. DJ34-mediated c-Myc depletion occurred in a wide range of tumor cell types, including lymphoma, lung, glioblastoma, breast cancer, and several forms of leukemia, with primary LSCs being particularly sensitive to DJ34. Further analyses revealed that DJ34 interferes with c-Myc synthesis at the level of transcription, and we provide data showing that DJ34 is a DNA intercalator and topoisomerase II inhibitor. Physiologically, DJ34 induced apoptosis, cell cycle arrest, and cell differentiation. Taken together, we have identified a novel compound that dually targets c-Myc and p53 in a wide variety of cancers, and with particularly strong activity against LSCs.

Cdk1 gates cell cycle-dependent tRNA synthesis by regulating RNA polymerase III activity.

tRNA genes are transcribed by RNA polymerase III (RNAPIII). During recent years it has become clear that RNAPIII activity is strictly regulated by the cell in response to environmental cues and the homeostatic status of the cell. However, the molecular mechanisms that control RNAPIII activity to regulate the amplitude of tDNA transcription in normally cycling cells are not well understood. Here, we show that tRNA levels fluctuate during the cell cycle and reveal an underlying molecular mechanism. The cyclin Clb5 recruits the cyclin dependent kinase Cdk1 to tRNA genes to boost tDNA transcription during late S phase. At tDNA genes, Cdk1 promotes the recruitment of TFIIIC, stimulates the interaction between TFIIIB and TFIIIC, and increases the dynamics of RNA polymerase III in vivo. Furthermore, we identified Bdp1 as a putative Cdk1 substrate in this process. Preventing Bdp1 phosphorylation prevented cell cycle-dependent recruitment of TFIIIC and abolished the cell cycle-dependent increase in tDNA transcription. Our findings demonstrate that under optimal growth conditions Cdk1 gates tRNA synthesis in S phase by regulating the RNAPIII machinery, revealing a direct link between the cell cycle and RNAPIII activity.

Lack of Correlation Between Natural Pelvic Tilt Angle with Hip Range of Motion, and Hip Muscle Torque Ratio.

Excessive anterior and posterior pelvic tilts (PT) angles are associated with overuse injuries of the lower limbs and of the lumbo-pelvic-hip complex. There is a lack of evidence that correlates anterior and posterior PT angles with limited hip internal rotation (IR) and external rotation (ER), and hip muscles torque ratios. The purpose of this study was to examine the correlation between averaged anterior/posterior PT angle in standing position and hip IR and ER range of motion (ROM), hip adductors and abductors (Add/Abd) torque ratio, and hip flexors and extensors (Flexor/Extensor) torque ratio. Twenty-six healthy participants participated in this study, fifteen females (22.0 ± 2.8 yrs, 163.5 ± 7.5 cm, 65.9 ± 10.4 kg) and eleven males (22.0 ± 2.2 yrs, 178.5 ± 4.5 cm, 78.4 ± 8.7 kg). Hip muscle torques were collected with an isokinetic dynamometer, five trials at 30 degrees per second (deg· s-1) and at 60 deg· s-1. The measurement of PT in standing natural position and hip IR and ER ROM in functional weight-bearing lunge position were recorded, using a 3D Motion Analysis System. There were no significant correlations between PT angle and hip IR and ER (p ≥ 0.05), no significant correlations between PT angle and hip Add/Abd torque ratio (p > 0.05), and no significant correlations between PT angle and hip Flexor/Extensor torque ratio (p > 0.05). The measurement of PT angle in standing natural position was not associated with hip IR and ER ROM and hip Add/Abd and Flexor/Extensor torque ratios, in healthy population.

[Medication prescription and transcription errors in a neonatal unit]. / Errores en la prescripción y transcripción de medicación en una unidad neonatal.

BACKGROUND: Medication errors occur because of pitfalls in one or more of the steps involved in the process of drug administration and should be considered as system errors. They should never be considered as human errors with assignment of responsibility. Rather, their causes should be analyzed to prevent repetition. The ultimate aim should be to improve working procedures to avoid these errors. PATIENTS AND METHODS: A total of 122 prescriptions were prospectively analyzed, along with their corresponding transcription to the nursing notes. Their legibility, dose, units, route of administration, and administration interval were evaluated. Units per kilogram of body weight and the use of generic names were also recorded. RESULTS: Prescription errors were detected in 35.2 % of the prescriptions reviewed. The most frequent errors were related to dosing (16.4 %). Analysis of the quality of the prescriptions revealed that 61.5 % of the drugs were prescribed by their generic name, but only 4.1 % specified the dose per kilogram of body weight. Errors were detected in 21.3 % of transcriptions, the most frequent being the absence of the administration route (7.4 %). The generic name was used in 57.4 % of the transcriptions. CONCLUSIONS: In the busy and complex environment of neonatal units, medication errors can be frequent. However, most of these errors are trivial and do not harm patients. Medication errors are indicators of the quality of the healthcare provided. Therefore, their detection and systematic analysis of their causes can contribute to their systematic prevention, thus improving the healthcare delivery process.

[Do neonates have the same pharmacotherapeutic opportunities as adults?]. / Tienen los recién nacidos las mismas oportunidades farmacoterapéuticas que los adultos?

INTRODUCTION: The use of drugs in pediatrics, specially in neonates, poses two main problems: the legal conditions for their use in this population and the lack of commercial formulations suitable for pediatric dosing. PATIENTS AND METHODS: We reviewed the drug prescriptions of all patients admitted to our neonatal intensive care unit over 46 days, chosen at random between September and November 2005. RESULTS: A total of 2,558 drug prescriptions were issued, corresponding to 62 different drugs. Overall, 5.2 % of prescriptions were for drugs not authorized for use in pediatric patients. In neonates, this percentage increased to 8.4 %. A total of 22.6 % of the drugs were not authorized for use in neonates. Formulations prepared by the hospital pharmacists were required in 17.2 % of drug prescriptions. CONCLUSIONS: In the last few years, information on drugs in pediatric patients has increased. However, continued efforts are required in this field so that drugs with proven clinical efficacy in pediatric patients become authorized for use in this population. Because of the lack of suitable commercial formulations for use in pediatric patients, preparation of formulations by the hospital pharmacist and the use of drug dilutions at the bedside are mandatory, both of which are a source of possible preparation and administration errors.