The RNA Polymerase II Elongation Factor ELL: Mechanism of Action and its Cross Regulation by Leukemogenic Oncoproteins

Transcription by RNA polymerase II (pol II) is a complex multistep process that encompasses pre-initiation complex (PIC) assembly, initiation, elongation and termination. The eleven-nineteen lysine-rich leukemia protein (ELL) is a pol II elongation factor that was initially discovered as a chromosomal translocation partner of the histone methyltransferase mixed lineage leukemia protein (MLL) in acute leukemia patients. Although biochemical and morphological studies in yeast and Drosophila have demonstrated significant insights into the role of ELL in transcription, the mechanisms underlying ELL function in mammalian systems and how its translocation with MLL leads to the progression of leukemia remain unclear. By applying combinations of gene depletion, subcellular localization, immunopurification and genome location analyses this study revealed that ELL bridges dynamic interactions that define two distinct rate-limiting steps in transcription. The first is early targeting and stabilization of the PIC containing pol II and the histone acetyltransferase p300. The second is stabilization and recruitment of additional transcription elongation factors including the positive transcription elongation factor b (P-TEFb), the AF4/FMR2 family member 4 protein (AFF4) and the pol II associated factor 1 (PAF1) to facilitate processive elongation and mRNA maturation. Furthermore, this study investigated the effects of MLL-ELL fusion and the human T cell lymphotropic/leukemia virus type I (HTLV-1) Tax oncoproteins on the assembly of cellular transcription complexes containing ELL. The results indicated that ELL is a "shared" or common transcriptional target of both MLL-ELL fusion and HTLV-1 Tax proteins. Enforced expression of either MLL-ELL fusion or Tax oncoprotein led to differential targeting of PIC containing ELL and p300 or elongation complex comprised of ELL in association with P-TEFb and AFF4 that culminate with activation of specific genes that promote proliferation. These finding suggest that due to its critical role in bridging dynamic interactions within the RNA pol II transcription cycle, ELL may represent a common point of vulnerability in multiple disease processes that is useful as a potential interface to exploit through therapeutic interventions

Performance evaluation of improved mung bean (Vigna radiata (L.) Wilczek) varieties at low moisture areas East Shewa, Oromia, Ethiopia

Mung bean is a useful crop in drier areas and has a good potential for crop rotation and relay cropping with cereals using residual moisture. The experiment was conducted at Adami Tulu Agricultural Research Center (ATARC), Lume and Dugda during 2018 and 2019 with the objective to identify adaptable and high yielder mung bean varieties for East Shewa Zone and similar agro ecologies. Four released mung bean varieties Shewa robit, Beroda, N-26 and Arkebe used as planting material. The experiment was laid down in Randomized Complete Block Design (RCBD) with three replications. The plot size was 1.8m × 2.5 m (4.5 m2) having 6 rows and a spacing of 0.30 m between rows and 50 cm between replication, 1 m between blocks. Data’s like  height (cm), number of pods per plant, number of seeds per pod, days to days to flowering, days to maturity, grain yield (kg ha-1), 100 seed weight (g) were collected and analyzed using SAS software.  The combined analysis of variance showed that there was significant variation at (P≤0.05 and P≤0.01) among the studied varieties, locations, and year main effect. There were also significant interaction effect on location by year, varieties by year and location by varieties by year for grain yield and other yield components. But non-significant on varieties by location for all traits except plant height and indicated those varieties were performed similarly across the locations.  Shewa Robit variety had a higher grain yield (1607.4 kg ha-1) followed by N-26 (1542 kg ha-1) and Beroda (1466.1 kg ha-1). While Arkebe Variety had a lower grain yield (893.4 kg ha-1) as compared with other varieties. Therefore Shewa Robit and N-26 were recommended for the study area and similar agro-ecologies

Perceived Implementation of Teacher Education Curriculum in Ethiopia: A Look for Congruence between Intended Reform and Actual Practice

This study compared the teaching and assessment practices of 396 randomly selected teacher educators drawn from 8 Colleges of Teacher Education (N=234) and Universities (N=162) throughout five regional states in Ethiopia. Data were collected using a 42-item questionnaire. The questionnaire was divided into two subscales as teaching practice subscale (TPS) and Assessment Practice Subscale (APS). In addition, a classroom observation checklist with 30 items was used to collect qualitative data from four classrooms. Findings indicated that about 81.4% of college instructors witnessed the constructivist-oriented implementation of the teacher education curricula in their respective institutions, while none of those in the universities remained either pure behaviorist or constructivist in overall teaching practice. Teacher educators in the two types of institutions are inclined towards constructivism, but still, colleges are superior to the universities in formative continuous assessment practice. The study concludes that the constructivist reform effort is supported by college-level teacher educators while universities preferred an eclectic position. Their assessment practices are also in agreement with the reform agenda, but teacher educators at colleges proved to be superior to their university counterparts. It is recommended that university-level teacher educators revisit their instructional management and technology integration practices to catch up with the planned reform

Macrocyclic toolbox from epothilone fragment identifies a compound showing molecular interactions with actin and novel promoters of apoptosis in patient-derived brain tumor cells

A simple, practical stereoselective synthesis of the epothilone fragment is developed to obtain a diverse set of expanded 18-membered macrocyclic compounds. These macrocycles contain the C5–C8 sub-unit of epothilone and an additional amino acid moiety incorporated in the 18-membered macrocycle, which allows the synthesis of several analogs with a variation in the chiral side chain. The epothilone fragment was obtained by using an enantiopure epoxide, which was subjected to a regioselective opening, giving the key derivative. Finally, the synthesis of the 18-membered macrocyclic ring was achieved by employing two key steps: (i) acylation with an N-allylated amino acid moiety, and (ii) a ring-closing metathesis (RCM) approach. Computational studies of the macrocyclic compounds obtained from this study with actin give rise to the proposed molecular interactions with the target protein. Further, the screening of our chemical toolbox from this program (i.e., the final products and several intermediates) identified several compounds as promoters of apoptosis in patient-derived brain tumor glioma cells

Incidence and geographic distribution of retinoblastoma in Ethiopia

Abstract Introduction Retinoblastoma is the most frequent intraocular malignancy of the eye in children, occurring in early childhood. Based on global estimates, Ethiopia is expected to observe over 200 new retinoblastoma cases per year, however without a cancer registry, this number is difficult to confirm. Therefore, the goal of the study was to determine the incidence and geographic distribution of retinoblastoma in Ethiopia. Methods A retrospective medical chart review of clinically diagnosed new retinoblastoma patients between January 1, 2017 - December 31, 2020, in four public Ethiopian tertiary hospitals was performed. The incidence of retinoblastoma was calculated by a birth-cohort analysis. Results There were 221 retinoblastoma patients observed in the study period. The incidence of retinoblastoma was found to be 1 in 52,156 live births. Incidence varied among different regions of Ethiopia. Conclusion The incidence of retinoblastoma observed in this study is likely an underestimate. It is possible that patients were undercounted because they were seen outside of the 4 main retinoblastoma treatment facilities included in this facility, or they experienced barriers to accessing care. Our study suggests a need for a nationwide retinoblastoma registry and more retinoblastoma treatment centers in the country

Phenotypic Screen Identifies a Small Molecule Modulating ERK2 and Promoting Stem Cell Proliferation

Stem cells display a fundamentally different mechanism of proliferation control when compared to somatic cells. Uncovering these mechanisms would maximize the impact in drug discovery with a higher translational applicability. The unbiased approach used in phenotype-based drug discovery (PDD) programs can offer a unique opportunity to identify such novel biological phenomenon. Here, we describe an integrated phenotypic screening approach, employing a combination of in vitro and in vivo PDD models to identify a small molecule increasing stem cell proliferation. We demonstrate that a combination of both in vitro and in vivo screening models improves hit identification and reproducibility of effects across various PDD models. Using cell viability and colony size phenotype measurement we characterize the structure activity relationship of the lead molecule, and identify that the small molecule inhibits phosphorylation of ERK2 and promotes stem cell proliferation. This study demonstrates a PDD approach that employs combinatorial models to identify compounds promoting stem cell proliferation

Transcriptional Autoregulation by BRCA1

The BRCA1 gene product plays numerous roles in regulating genome integrity. Its role in assembling supermolecular complexes in response to DNA damage has been extensively studied; however, much less is understood about its role as a transcriptional coregulator. Loss or mutation is associated with hereditary breast and ovarian cancers, whereas altered expression occurs frequently in sporadic forms of breast cancer, suggesting that the control of BRCA1 transcription might be important to tumorigenesis. Here, we provide evidence of a striking linkage between the roles for BRCA1 as a transcriptional coregulator with control of its expression via an autoregulatory transcriptional loop. BRCA1 assembles with complexes containing E2F-1 and RB to form a repressive multicomponent transcriptional complex that inhibits BRCA1 promoter transcription. This complex is disrupted by genotoxic stress, resulting in the displacement of BRCA1 protein from the BRCA1 promoter and subsequent upregulation of BRCA1 transcription. Cells depleted of BRCA1 respond by upregulating BRCA1 transcripts, whereas cells overexpressing BRCA1 respond by downregulating BRCA1 transcripts. Tandem chromatin immmunoprecipitation studies show that BRCA1 is regulated by a dynamic coregulatory complex containing BRCA1, E2F1, and Rb at the BRCA1 promoter that is disrupted by DNA-damaging agents to increase its transcription. These results define a novel transcriptional mechanism of autoregulated homeostasis of BRCA1 that selectively titrates its levels to maintain genome integrity in response to genotoxic insult.Fil: de Siervi, Adriana. National Cancer Institute; Estados Unidos. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: de Luca, Paola. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Byun, Jung S.. National Cancer Institute; Estados UnidosFil: Di, Li Jun. National Cancer Institute; Estados UnidosFil: Fufa, Temesgen. National Cancer Institute; Estados UnidosFil: Haggerty, Cynthia M.. National Cancer Institute; Estados UnidosFil: Vazquez, Elba Susana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Moiola, Cristian Pablo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Longo, Dan L.. National Institute on Aging; Estados UnidosFil: Gardner, Kevin. National Cancer Institute; Estados Unido

Phenotypic Screen Identifies a Small Molecule Modulating ERK2 and Promoting Stem Cell Proliferation

Stem cells display a fundamentally different mechanism of proliferation control when compared to somatic cells. Uncovering these mechanisms would maximize the impact in drug discovery with a higher translational applicability. The unbiased approach used in phenotype-based drug discovery (PDD) programs can offer a unique opportunity to identify such novel biological phenomenon. Here, we describe an integrated phenotypic screening approach, employing a combination of in vitro and in vivo PDD models to identify a small molecule increasing stem cell proliferation. We demonstrate that a combination of both in vitro and in vivo screening models improves hit identification and reproducibility of effects across various PDD models. Using cell viability and colony size phenotype measurement we characterize the structure activity relationship of the lead molecule, and identify that the small molecule inhibits phosphorylation of ERK2 and promotes stem cell proliferation. This study demonstrates a PDD approach that employs combinatorial models to identify compounds promoting stem cell proliferation

A direct link between MITF, innate immunity, and hair graying

<div><p>Melanocyte stem cells (McSCs) and mouse models of hair graying serve as useful systems to uncover mechanisms involved in stem cell self-renewal and the maintenance of regenerating tissues. Interested in assessing genetic variants that influence McSC maintenance, we found previously that heterozygosity for the melanogenesis associated transcription factor, <i>Mitf</i>, exacerbates McSC differentiation and hair graying in mice that are predisposed for this phenotype. Based on transcriptome and molecular analyses of <i>Mitf</i>^{<i>mi-vga9/+</i>} mice, we report a novel role for MITF in the regulation of systemic innate immune gene expression. We also demonstrate that the viral mimic poly(I:C) is sufficient to expose genetic susceptibility to hair graying. These observations point to a critical suppressor of innate immunity, the consequences of innate immune dysregulation on pigmentation, both of which may have implications in the autoimmune, depigmenting disease, vitiligo.</p></div