The Suv420h histone methyltransferases regulate PPAR-γ and energy expenditure in response to environmental stimuli.

Obesity and its associated metabolic abnormalities have become a global emergency with considerable morbidity and mortality. Epidemiologic and animal model data suggest an epigenetic contribution to obesity. Nevertheless, the cellular and molecular mechanisms through which epigenetics contributes to the development of obesity remain to be elucidated. Suv420h1 and Suv420h2 are histone methyltransferases responsible for chromatin compaction and gene repression. Through in vivo, ex vivo, and in vitro studies, we found that Suv420h1 and Suv420h2 respond to environmental stimuli and regulate metabolism by down-regulating peroxisome proliferator-activated receptor gamma (PPAR-γ), a master transcriptional regulator of lipid storage and glucose metabolism. Accordingly, mice lacking Suv420h proteins activate PPAR-γ target genes in brown adipose tissue to increase mitochondria respiration, improve glucose tolerance, and reduce adipose tissue to fight obesity. We conclude that Suv420h proteins are key epigenetic regulators of PPAR-γ and the pathways controlling metabolism and weight balance in response to environmental stimuli.

Assessment of the key regulatory genes and their Interologs for Turner Syndrome employing network approach.

Turner Syndrome (TS) is a condition where several genes are affected but the molecular mechanism remains unknown. Identifying the genes that regulate the TS network is one of the main challenges in understanding its aetiology. Here, we studied the regulatory network from manually curated genes reported in the literature and identified essential proteins involved in TS. The power-law distribution analysis showed that TS network carries scale-free hierarchical fractal attributes. This organization of the network maintained the self-ruled constitution of nodes at various levels without having centrality-lethality control systems. Out of twenty-seven genes culminating into leading hubs in the network, we identified two key regulators (KRs) i.e. KDM6A and BDNF. These KRs serve as the backbone for all the network activities. Removal of KRs does not cause its breakdown, rather a change in the topological properties was observed. Since essential proteins are evolutionarily conserved, the orthologs of selected interacting proteins in C. elegans, cat and macaque monkey (lower to higher level organisms) were identified. We deciphered three important interologs i.e. KDM6A-WDR5, KDM6A-ASH2L and WDR5-ASH2L that form a triangular motif. In conclusion, these KRs and identified interologs are expected to regulate the TS network signifying their biological importance.

Chemical exposure and infant leukaemia: development of an adverse outcome pathway (AOP) for aetiology and risk assessment research.

Infant leukaemia (<1 year old) is a rare disease of an in utero origin at an early phase of foetal development. Rearrangements of the mixed-lineage leukaemia (MLL) gene producing abnormal fusion proteins are the most frequent genetic/molecular findings in infant B cell-acute lymphoblastic leukaemia. In small epidemiological studies, mother/foetus exposures to some chemicals including pesticides have been associated with infant leukaemia; however, the strength of evidence and power of these studies are weak at best. Experimental in vitro or in vivo models do not sufficiently recapitulate the human disease and regulatory toxicology studies are unlikely to capture this kind of hazard. Here, we develop an adverse outcome pathway (AOP) based substantially on an analogous disease-secondary acute leukaemia caused by the topoisomerase II (topo II) poison etoposide-and on cellular and animal models. The hallmark of the AOP is the formation of MLL gene rearrangements via topo II poisoning, leading to fusion genes and ultimately acute leukaemia by global (epi)genetic dysregulation. The AOP condenses molecular, pathological, regulatory and clinical knowledge in a pragmatic, transparent and weight of evidence-based framework. This facilitates the interpretation and integration of epidemiological studies in the process of risk assessment by defining the biologically plausible causative mechanism(s). The AOP identified important gaps in the knowledge relevant to aetiology and risk assessment, including the specific embryonic target cell during the short and spatially restricted period of susceptibility, and the role of (epi)genetic features modifying the initiation and progression of the disease. Furthermore, the suggested AOP informs on a potential Integrated Approach to Testing and Assessment to address the risk caused by environmental chemicals in the future.

A structured assessment of motor function and behavior in patients with Kleefstra syndrome.

The present study aimed to further our understanding of Kleefstra syndrome, especially regarding motor function and behavioral characteristics. In total, four males and four females between two and 27 years of age with a genetically confirmed diagnosis of Kleefstra syndrome and their parents participated in this study. Four patients had 9q34.3 deletions that caused Euchromatin Histone Methyl Transferase 1 (EHMT1) haplo-insufficiency, and four patients harbored EHMT1 mutations. The motor function was evaluated via systematic observation. Standardized assessments such as the Vineland Adapted Behavior Scales II (VABS II), the Social Communication Questionnaire (SCQ) and the Child or Adult Behavior Checklist (CBCL, ABCL) were used for the behavioral assessment. All patients showed a delayed developmental status. Muscular hypotonia and its manifestations were present in all patients, regardless of their age. The mean values for all VABS II domains (communication, socialization, daily living skills, and motor skills) were significantly lower than the mean of the reference population (p < 0.001), but similar to other rare intellectual disabilities such as Smith-Magenis syndrome and Angelman syndrome. The results from the SCQ indicated that all patient values exceeded the cut-off value, suggesting the possibility of autism spectrum disorder. The behavioral and emotional problems assessed by CBCL and ABCL were less frequent. In conclusion, patients with Kleefstra syndrome present with a broad range of clinical problems in all age groups and are therefore in need of a multidisciplinary follow-up also after their transition into adulthood.

Assessment of MLL methyltransferase gene expression in larynx carcinoma.

Larynx cancer is the second most common type of cancer among all head and neck cancers. Deregulation of epigenetic effectors, including altered expression of histone methyltransferases from the MLL (mixed lineage leukemia) family, have been reported in many cancer types, yet little is known concerning their involvement in larynx cancer. Our objective was to determine the expression profile of MLL genes in larynx carcinoma and normal adjacent tissues and correlate this profile to tumor characteristics. We analyzed the expression profile of 5 MLL genes in 13 cases of larynx carcinoma and their adjacent non-tumor tissues using quantitative real-time PCR. MLL3 was significantly downregulated in tumor samples compared to their normal counterparts, and all MLL genes showed decreased expression in advanced tumors compared to tumors in the initial stage. Altered expression in a single MLL gene was associated with a similar alteration in the other MLL genes, revealing a strong correlation of expression in each individual patient. In conclusion, MLL genes may have similar transcriptional control, and decreased expression of these genes may contribute to larynx cancer progression.