Chromatin insulator mechanisms ensure accurate gene expression by controlling overall 3D genome organization.

Chromatin insulators are DNA-protein complexes that promote specificity of enhancer-promoter interactions and maintain distinct transcriptional states through control of 3D genome organization. In this review, we highlight recent work visualizing how mammalian CCCTC-binding factor acts as a boundary to dynamic DNA loop extrusion mediated by cohesin. We also discuss new studies in both mammals and Drosophila that elucidate biological redundancy of chromatin insulator function and interplay with transcription with respect to topologically associating domain formation. Finally, we present novel concepts in spatiotemporal regulation of chromatin insulator function during differentiation and development and possible consequences of disrupted insulator activity on cellular proliferation.

Steroid hormone signaling synchronizes cell migration machinery, adhesion and polarity to direct collective movement.

Migratory cells - either individually or in cohesive groups - are critical for spatiotemporally regulated processes such as embryonic development and wound healing. Their dysregulation is the underlying cause of formidable health problems such as congenital abnormalities and metastatic cancers. Border cell behavior during Drosophila oogenesis provides an effective model to study temporally regulated, collective cell migration in vivo. Developmental timing in flies is primarily controlled by the steroid hormone ecdysone, which acts through a well-conserved, nuclear hormone receptor complex. Ecdysone signaling determines the timing of border cell migration, but the molecular mechanisms governing this remain obscure. We found that border cell clusters expressing a dominant-negative form of ecdysone receptor extended ineffective protrusions. Additionally, these clusters had aberrant spatial distributions of E-cadherin (E-cad), apical domain markers and activated myosin that did not overlap. Remediating their expression or activity individually in clusters mutant for ecdysone signaling did not restore proper migration. We propose that ecdysone signaling synchronizes the functional distribution of E-cadherin, atypical protein kinase C (aPKC), Discs large (Dlg1) and activated myosin post-transcriptionally to coordinate adhesion, polarity and contractility and temporally control collective cell migration.

Mind bomb 2 promotes cell migration and epithelial structure by regulating adhesion complexes and the actin cytoskeleton.

Cell migration is essential in animal development and co-opted during metastasis and inflammatory diseases. Some cells migrate collectively, which requires them to balance epithelial characteristics such as stable cell-cell adhesions with features of motility like rapid turnover of adhesions and dynamic cytoskeletal structures. How this is regulated is not entirely clear but important to understand. While investigating Drosophila oogenesis, we found that the putative E3 ubiquitin ligase, Mind bomb 2 (Mib2), is required to promote epithelial stability and the collective cell migration of border cells. Through biochemical analysis, we identified components of Mib2 complexes, which include E-cadherin and α- and ß-catenins, as well as actin regulators. We also found that three Mib2 interacting proteins, RhoGAP19D, Supervillin, and Myosin heavy chain-like, affect border cell migration. mib2 mutant main body follicle cells have drastically reduced E-cadherin-based adhesion complexes and diminished actin filaments. We conclude that Mib2 acts to stabilize E-cadherin-based adhesion complexes and promote a robust actin cytoskeletal network, which is important for maintenance of epithelial integrity. The interaction with cadherin adhesion complexes and other cytoskeletal regulators contribute to its role in collective cell migration. Since Mib2 is well conserved, it may have similar functional significance in other organisms.

Pretreatment of Leucaena leucocephala wood by acidified glycerol: optimization, severity index and correlation analysis.

In this study, Leucaena leucocephala wood was pretreated with aqueous glycerol having H2SO4 as the catalyst. Response surface methodology (RSM) and artificial neural network (ANN) were used to optimize the process parameters, catalyst concentration (1-3%), duration (120-300 min) and temperature (100-150 °C). ANN gave more accurate predictions for total reducing sugar yield than RSM. ANN also had lower values for error functions. Severity index (SI) was calculated based on the temperature, duration and catalyst concentration. Increase in SI from 0.21 * 103 to 2.06 * 103 increased total reducing sugar (TRS) production from 39.97 g/kg to 321.8 g/kg. Further increase in SI reduced the TRS and this change positively correlates with the loss of cellulose content. Correlation analysis showed that severity index can also be used to describe pretreatment process.

Ciprofloxacin treatment in preterm neonates in Bangladesh: lack of effects on growth and development.

BACKGROUND: Quinolone-induced arthropathic toxicity in weight-bearing joints observed in juvenile animals during preclinical testing has largely restricted the routine use of ciprofloxacin in the pediatric age group. As histopathologic, radiologic and magnetic resonance imaging monitoring evidence has gathered supporting the safety of fluoroquinolones in children, many pediatricians have started to prescribe quinolones to some patients on a compassionate basis. OBJECTIVE: The objective of this study was to ascertain the safety of ciprofloxacin in preterm neonates <33 weeks gestational age treated at Dhaka Shishu (Children) Hospital in Bangladesh. METHODS: Long-term follow up was done to monitor the growth and development of preterm infants who were administered intravenous ciprofloxacin in the neonatal period. Ciprofloxacin was used only as a life-saving therapy in cases of sepsis produced by bacterial agents resistant to other antibiotics. Another group of preterm neonates with septicemia who were not exposed to ciprofloxacin, but effectively treated with other antibiotics and followed up, were matched with cases for gender, gestational age and birth weight and included as a comparison group. Forty-eight patients in the ciprofloxacin group and 66 patients in the comparison group were followed up for a mean of 24.7 +/- 18.5 months and 21.6 +/- 18.8 months, respectively. RESULTS: No osteoarticular problems or joint deformities were observed in the ciprofloxacin group during treatment or follow up. No differences in growth and development between the groups were found. CONCLUSIONS: Ciprofloxacin is a safe therapeutic option for newborns with sepsis produced by multiply resistant organisms.

Neurodevelopmental outcomes of preterm infants in Bangladesh.

OBJECTIVES: The purpose of this work was to determine neurodevelopmental outcomes of preterm infants followed by a multidisciplinary team in a tertiary hospital in Bangladesh. METHODS: Infants <33 weeks' gestational age were serially assessed for neurodevelopment by physicians and developmental psychologists. An estimate of "low," "moderate," or "high" risk for neurodevelopmental impairments was made at the first visit. At later assessments, neurodevelopmental impairments were graded by severity as "none," "mild," or "serious." RESULTS: Of the 159 enrolled children, 65% survived, 16% died, and 19% were lost to follow-up. Family income was lowest among those who died, and maternal and paternal literacy was highest among the survivors. At a mean age of 31 months, developmental status of the 85 children followed-up for > or = 12 months was normal in 32%; 45% had mild and 23% had serious neurodevelopmental impairments. Cognitive impairment was the most common deficit (60%). Final outcome was significantly better than estimated initially. Most serious (85%) but fewer mild (37%) problems were identified independently by both child health physicians and psychologists. CONCLUSIONS: Parental education and family income had significant influence on postdischarge mortality. Two thirds of infants demonstrated neurodevelopmental impairments. Most mild cognitive impairments would have been missed had either physicians or psychologists alone done the assessments. Preterm infants in this low-resource setting are at high risk for neurodevelopmental impairments, which need to be identified early, preferably by a multidisciplinary team of professionals.