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1.
Acad Med ; 99(7): 810, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38574246
2.
Leukemia ; 38(4): 865-876, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38388647

ABSTRACT

Racial and socioeconomic disparities impact outcomes after chemotherapy and limit access to allogeneic hematopoietic cell transplantation (HCT) in acute myeloid leukemia (AML), yet studies have yielded mixed results on the influence of disparities on post-HCT outcomes. Therefore, we studied 1024 adults with AML who underwent allogeneic HCT between 5/2006 and 10/2021 at a single large university-affiliated cancer center. Collected data included non-biologic and demographic characteristics (including race/ethnicity, marital status, distance traveled, and household size), transplant- and disease-related characteristics, and area-level and individual-level socioeconomic factors (i.e., area deprivation index and occupational status). After multivariable adjustment, no socioeconomic- or non-biologic factors were associated with non-relapse mortality (NRM), overall survival (OS), relapse-free survival (RFS), or relapse except being married (associated with improved NRM: hazard ratio [HR] = 0.7 [0.50-0.97]) and having no insurance (associated with worse OS: HR = 1.49 [1.05-2.12] and RFS: HR = 1.41 [1.00-1.98]). Despite a relatively racially homogenous cohort, Asian race was associated with improved NRM (HR = 0.47 [0.23-0.93]) and American Indian/Alaskan Native race was associated with higher relapse risk (HR = 2.45 [1.08-5.53]). In conclusion, in our retrospective analysis, socioeconomic-, demographic-, and non-biologic factors had limited impact on post-HCT outcomes in AML patients allografted in morphologic remission. Further research is needed to investigate disparities among HCT-eligible patients.


Subject(s)
Hematopoietic Stem Cell Transplantation , Leukemia, Myeloid, Acute , Adult , Humans , Retrospective Studies , Socioeconomic Disparities in Health , Hematopoietic Stem Cell Transplantation/methods , Recurrence , Transplantation Conditioning/methods
3.
Childs Nerv Syst ; 38(8): 1497-1504, 2022 08.
Article in English | MEDLINE | ID: mdl-35588333

ABSTRACT

PURPOSE: To describe the design, implementation, and adoption of a simplified electronic medical record (EMR) and its use in documenting pediatric central nervous system (CNS) tumors at a tertiary care referral hospital in South-East Asia. METHODS: A novel EMR, cataloguing pediatric CNS tumors was used to collect data from August 2017 to March 2020 at National Institute of Neurosciences and Hospital (NINS&H) in Dhaka, Bangladesh. RESULTS: Two hundred forty-nine pediatric patients with a CNS tumor were admitted to NINS&H. Fifty-eight percent of patients were male, and the median age was 8 years. A total of 188/249 patients (76%) underwent surgery during their index admission. Radiographic locations were known for 212/249 (85%) of cases; the most common radiographic locations were infratentorial (81/212; 38%), suprasellar (45/212; 21%), and supratentorial (29/212; 14%). A histopathological classification was reported on 156/249 (63%) of patients' cytology. The most common infratentorial pathologies were medulloblastoma (22/47; 47%) and pilocytic astrocytoma (14/47; 30%). The median time between admission and surgery was 36 days, while the median post-operation stay was 19.5 days. CONCLUSIONS: The feasibility of a basic EMR platform for a busy pediatric neurosurgery department in a lower-middle income country is demonstrated, and preliminary clinical data is reviewed. A wide variety of pediatric CNS tumors were observed, spanning the spectrum of anatomic locations and histopathologic subtypes. Surgical intervention was performed for the majority of patients. Barriers to care include limited molecular diagnostics and unavailable data on adjuvant therapy. Future targets include improvement of clinical documentation in the pre-operative and post-operative period.


Subject(s)
Astrocytoma , Central Nervous System Neoplasms , Cerebellar Neoplasms , Bangladesh , Central Nervous System Neoplasms/diagnostic imaging , Central Nervous System Neoplasms/surgery , Child , Electronic Health Records , Female , Humans , Male
4.
R I Med J (2013) ; 104(7): 42-45, 2021 Sep 01.
Article in English | MEDLINE | ID: mdl-34437665

ABSTRACT

We report a 73-year-old male with recurrent amelanotic malignant melanoma of the left foot with in-transit metastases to the left thigh. In-transit metastatic melanoma can often represent a diagnostic and therapeutic challenge for physicians. This patient was treated with talimogene laherparepvec injections (T-VEC; Imlygic) in the left inguinal and the left plantar region every two weeks for one year as oncolytic viral therapy for advanced non- operable malignant melanoma. He then received consistent follow-up including blood work and PET scans every four months, and he also required further lymph node surgical dissection. To date, our patient has survived 3 years and 11 months, which is 27 months longer than the esti- mated median survival of 1 year 8 months for patients diagnosed with in-transit metastatic melanoma.


Subject(s)
Melanoma , Oncolytic Virotherapy , Skin Neoplasms , Aged , Humans , Male , Melanoma/therapy , Skin Neoplasms/therapy
5.
J Biol Chem ; 297(2): 100947, 2021 08.
Article in English | MEDLINE | ID: mdl-34270961

ABSTRACT

Transcription factors (TFs) harboring broad-complex, tramtrack, and bric-a-brac (BTB) domains play important roles in development and disease. These BTB domains are thought to recruit transcriptional modulators to target DNA regions. However, a systematic molecular understanding of the mechanism of action of this TF family is lacking. Here, we identify the zinc finger BTB-TF Zbtb2 from a genetic screen for regulators of exit from pluripotency and demonstrate that its absence perturbs embryonic stem cell differentiation and the gene expression dynamics underlying peri-implantation development. We show that ZBTB2 binds the chromatin remodeler Ep400 to mediate downstream transcription. Independently, the BTB domain directly interacts with nucleosome remodeling and deacetylase and histone chaperone histone regulator A. Nucleosome remodeling and deacetylase recruitment is a common feature of BTB TFs, and based on phylogenetic analysis, we propose that this is a conserved evolutionary property. Binding to UBN2, in contrast, is specific to ZBTB2 and requires a C-terminal extension of the BTB domain. Taken together, this study identifies a BTB-domain TF that recruits chromatin modifiers and a histone chaperone during a developmental cell state transition and defines unique and shared molecular functions of the BTB-domain TF family.


Subject(s)
Repressor Proteins , Transcription Factors , BTB-POZ Domain , Histone Chaperones , Humans , Phylogeny , Zinc Fingers
6.
Case Rep Endocrinol ; 2021: 5571524, 2021.
Article in English | MEDLINE | ID: mdl-34194850

ABSTRACT

BACKGROUND: Growth hormone (GH) treatment increases the adult height of short children born small for gestational age (SGA). Catch-up growth is associated with a younger age, shorter height, and prepubertal status at the onset of GH treatment. We report a 12 11/12-year-old girl born SGA who received GH for 5 years without catch-up growth and was diagnosed with Noonan Syndrome (NS). RESULTS: A 5-year-and-9-month-old 46, XX girl born SGA was started on GH treatment at a dose of 0.32 mg/kg/week. Her midparental target height is 158.6 cm. Endocrine work up showed an IGF-1 level 69 ng/ml (Normal (N): 55-238 ng/ml), IGFBP3 2.6 mg/L (N: 1.9-5.2 mg/L), TSH 3.2 mIU/L (N: 0.35-5.5 mIU/L), and a normal skeletal survey. Height was 96 cm (0.1%; Ht SDS -2.9), weight 14 kgs (1%; Wt SDS -2.3), and Tanner 1 breast and pubic hair were observed. Due to the poor catch-up growth on GH treatment, she was referred to Genetics to elucidate genetic or syndromic causes of short stature. She was noted to have posteriorly rotated ears and slight down slanting of the palpebral fissures. Genetic findings showed a heterozygous pathogenic variant in PTPN11 (c.922A > G (p.Asn308Asp)) diagnostic for NS. This finding is de novo given negative parental testing. She was noted to have a heterozygous missense variant of unknown significance (VUS) in FGFR3: c.746C > A (p.Ser249Tyr). FGFR3 is associated with multiple skeletal dysplasias including thanatophoric dysplasia, achondroplasia, and Crouzon syndrome and hypochondroplasia. Clinical correlation is poor for these syndromes. CONCLUSION: Diminished catch-up growth and response to GH treatment in a child born SGA led to the diagnosis of NS. The concomitant diagnosis of SGA and NS may have affected the responsiveness of this child to the growth promoting effect of GH treatment.

8.
EMBO J ; 40(12): e106818, 2021 06 15.
Article in English | MEDLINE | ID: mdl-33909924

ABSTRACT

Mouse embryonic stem cells (mESCs) are biased toward producing embryonic rather than extraembryonic endoderm fates. Here, we identify the mechanism of this barrier and report that the histone deacetylase Hdac3 and the transcriptional corepressor Dax1 cooperatively limit the lineage repertoire of mESCs by silencing an enhancer of the extraembryonic endoderm-specifying transcription factor Gata6. This restriction is opposed by the pluripotency transcription factors Nr5a2 and Esrrb, which promote cell type conversion. Perturbation of the barrier extends mESC potency and allows formation of 3D spheroids that mimic the spatial segregation of embryonic epiblast and extraembryonic endoderm in early embryos. Overall, this study shows that transcriptional repressors stabilize pluripotency by biasing the equilibrium between embryonic and extraembryonic lineages that is hardwired into the mESC transcriptional network.


Subject(s)
DAX-1 Orphan Nuclear Receptor , Histone Deacetylases , Mouse Embryonic Stem Cells/cytology , Animals , Cell Differentiation , Cells, Cultured , DAX-1 Orphan Nuclear Receptor/genetics , DAX-1 Orphan Nuclear Receptor/metabolism , Female , GATA6 Transcription Factor/genetics , Histone Deacetylases/genetics , Histone Deacetylases/metabolism , Male , Mice , RNA, Small Interfering/genetics , Receptors, Cytoplasmic and Nuclear/genetics , Receptors, Cytoplasmic and Nuclear/metabolism , Receptors, Estrogen/genetics , Receptors, Estrogen/metabolism
9.
Clin Exp Ophthalmol ; 49(4): 347-356, 2021 May.
Article in English | MEDLINE | ID: mdl-33751766

ABSTRACT

BACKGROUND: Transnational ophthalmic partnerships exist between high-income countries (HICs) and low- and middle-income countries (LMICs) in varying capacities. We analyzed partnership stakeholders to better understand and address disparities in ophthalmic surgical care. METHODS: An international Web search was conducted to identify surgeons, foundations or organisations participating in ophthalmic delivery and/or capacity building from 2010 to 2019. Partnerships were defined through clinical activities, education and training and/or research support. Descriptive data on current ophthalmic partnerships were collected from published reports, literature reviews and information on stakeholder webpages. Partnerships were classified by the extent of engagement and training: grade I 'engagement' represented documented partnerships of at least 1 year and grade I 'training' limited or poorly defined skills transfer programmes, while grade III 'engagement' represented partnerships with well-documented fiscal investment and/or research productivity and grade III 'training' established training programmes. Data were analysed using descriptive statistics and geospatially depicted on Tableau (Mountain View, CA) and ArcMap software (Redlands, CA). RESULTS: In total, 209 unique HIC-LMIC partnerships encompassing 92 unique countries were described. The most common HIC partners were from North America (123; 59%), followed by Europe (75; 36%). The most common LMIC partners were from Africa (102; 49%), followed by Asia-Pacific (54; 26%) and Latin America (44; 21%). Additionally, partnerships most frequently provided services in cataract (48%), glaucoma (25%) and diabetic retinopathy (25%). The most common 'engagement' classifications were grade I (36%) or II (40%); the most common 'training' classifications were grade I (61%) or II (23%). CONCLUSION: Transnational ophthalmic partnerships exist with varying degrees of both engagement and training. Partnerships are stronger in research collaboration and direct services, and weaker in LMIC-directed training programmes.


Subject(s)
Capacity Building , Income , Asia , Developing Countries , Humans
10.
11.
12.
World Neurosurg ; 144: e898-e907, 2020 12.
Article in English | MEDLINE | ID: mdl-32992055

ABSTRACT

OBJECTIVE: To evaluate the presence, extent, and temporality of transnational neurosurgical partnerships, to understand and inform measures to address neurosurgical deficiencies in low- and middle-income countries (LMICs). METHODS: A Web search was conducted to identify actors from high-income countries (HICs) participating in neurosurgical delivery and/or capacity-building with LMICs from 2010 to 2018. Descriptive data on current neurosurgical partnerships were collected from published case reports, literature reviews, reports from academic institutions, and information on stakeholder Web pages. The level of training and engagement of each partnership was separately graded based on prespecified criteria, in which grade 3 represented partnerships that have most extensive training and engagement, and grade 1, the least extent. Data were analyzed using descriptive statistics and geospatially depicted on ArcMap GIS software. RESULTS: A total of 123 unique HIC-LMIC partnerships were described. Of these partnerships, 85 (69%) are derived from HICs in North America, followed by Europe, with 23 (19%). The most common LMIC partners were from Africa (n = 56, 45%) and Latin America (n = 32, 26%). In addition, most partnerships provided services in pediatric neurosurgery (88%). The most frequent engagement classifications were grade 2 (35%) or 1 (36%). Similarly, for training, the most common classifications were grade 1 (40%) or 2 (30%). CONCLUSIONS: A robust network of HIC-LMIC partnerships exists with varying degrees of engagement and training activities. Several regions are particularly suitable for growth and development. Systematic consolidation and indexing of transnational neurosurgical partnerships aim to enhance resource allocation and present opportunities for future partnership.


Subject(s)
Developing Countries/statistics & numerical data , Neurosurgery/education , Neurosurgical Procedures/education , Capacity Building , Humans , World Health Organization
13.
Parasit Vectors ; 13(1): 379, 2020 Jul 29.
Article in English | MEDLINE | ID: mdl-32727610

ABSTRACT

BACKGROUND: Understanding local Anopheles species compositions and bionomic traits are vital for an effective malaria vector intervention strategy. Though eight malaria vectors, including species complexes, have been documented across the island of Sulawesi, Indonesia, a comprehensive survey linking morphological and molecular species identification has not been conducted in this global hotspot of biodiversity. RESULTS: Eighteen distinct species of Anopheles were molecularly identified in a 1 km2 area in Karama village, West Mamuju Province, Sulawesi. Known species included An. aconitus, An. karwari, An. peditaeniatus, An. vagus, An. barbirostris, An. tessellatus, An. nigerrimus, An. crawfordi, An. maculatus, An. flavirostris and An. kochi. Of the 18 distinct sequence groups identified through both ribosomal DNA internal transcribed spacer region 2, and mitochondrial DNA cytochrome c oxidase subunit 1 loci, 8 could not be identified to species through comparison to published sequences. The comparison of morphological and molecular identities determined that interpretations of local species compositions for primary and expected species in Karama (An. barbirostris and An. vagus) had the highest rate of accuracy (92.1% and 87.6%, respectively) when compared to molecular analysis. However, the remaining distinct sequences molecularly identified to species were identified correctly by morphological methods less frequently, from 0 to 83%. CONCLUSIONS: Karama, Indonesia has a high diversity of Anopheles spp. The unexpected high number of Anopheles species in a small area points to possible complex transmission dynamics and limitations with vector control based on possible varying behaviors and interactions with both humans and interventions. Morphological identification of Anopheles spp. in this study was more accurate for primary and expected species than secondary or unexpected species. Finally, the inability to identify seven sequence groups to species with consensus sequences implies that future studies employing sequencing are required to clarify species compositions in the Nigerrimus Subgroup, among others, as well as their distribution and vector status. Use of molecular methods in conjunction with morphological investigations for analysis of species composition, population dynamics and bionomic characteristics is directly implicated in understanding drivers of malaria transmission, intervention effectiveness, and the pursuit of malaria elimination.


Subject(s)
Anopheles , Biodiversity , Animals , Anopheles/anatomy & histology , Anopheles/classification , Anopheles/genetics , Classification , DNA, Ribosomal Spacer/genetics , Electron Transport Complex IV/genetics , Genes, Insect , Humans , Indonesia , Malaria/transmission , Mosquito Vectors/anatomy & histology , Mosquito Vectors/classification , Mosquito Vectors/genetics
14.
Mil Med ; 185(7-8): e972-e976, 2020 08 14.
Article in English | MEDLINE | ID: mdl-32412083

ABSTRACT

INTRODUCTION: Glaucoma surgical practice patterns are not well described in the United States (US). This study aims to evaluate the indications for and potential barriers to glaucoma surgery in the Veterans Health Administration (VHA). MATERIALS AND METHODS: An anonymous 10-question survey using REDCap (Nashville, TN) software was sent by mail (with web link) and email to ophthalmology chiefs at the 86 academically affiliated Veterans Affairs Medical Centers (VAMCs). Academic-affiliated VAMCs were selected because of their patient range and role in ophthalmic education. Non-responders received two reminder e-mails and two phone calls; the survey was closed after 6 weeks. The data were analyzed using descriptive statistics. RESULTS: The response rate was 45% (39/86). Most respondents (92%) worked in an integrated eye clinic with both ophthalmology and optometry services. Almost half of the respondents (49%; 19/39) believed that laser trabeculoplasty (LTP) was an option for initial glaucoma therapy. Noncompliance was a commonly reported indication for LTP (95%), tube shunt procedures (65%), micro-invasive glaucoma surgery (59%), and trabeculectomy (48.7%). One third of the respondents believed that there were delays in glaucoma care. The respondents noted that significant barriers in access to surgery included lack of transportation (69%), scheduling challenges (62%), and delayed referral (62%). CONCLUSION: This survey of glaucoma surgery practice patterns highlights the growing role of LTP and suggests that non-compliance and access remain significant barriers to glaucoma surgical care within the VHA.


Subject(s)
Glaucoma , Trabeculectomy , Veterans Health , Glaucoma/surgery , Humans , Ophthalmology , Surveys and Questionnaires , United States
15.
Cell Stem Cell ; 24(2): 257-270.e8, 2019 02 07.
Article in English | MEDLINE | ID: mdl-30595499

ABSTRACT

Self-renewal and differentiation of pluripotent murine embryonic stem cells (ESCs) is regulated by extrinsic signaling pathways. It is less clear whether cellular metabolism instructs developmental progression. In an unbiased genome-wide CRISPR/Cas9 screen, we identified components of a conserved amino-acid-sensing pathway as critical drivers of ESC differentiation. Functional analysis revealed that lysosome activity, the Ragulator protein complex, and the tumor-suppressor protein Folliculin enable the Rag GTPases C and D to bind and seclude the bHLH transcription factor Tfe3 in the cytoplasm. In contrast, ectopic nuclear Tfe3 represses specific developmental and metabolic transcriptional programs that are associated with peri-implantation development. We show differentiation-specific and non-canonical regulation of Rag GTPase in ESCs and, importantly, identify point mutations in a Tfe3 domain required for cytoplasmic inactivation as potentially causal for a human developmental disorder. Our work reveals an instructive and biomedically relevant role of metabolic signaling in licensing embryonic cell fate transitions.


Subject(s)
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors/metabolism , Cell Differentiation , Lysosomes/metabolism , Signal Transduction , Alleles , Animals , Cell Self Renewal , Female , GTP Phosphohydrolases/metabolism , Genome , Humans , Male , Mice , Mouse Embryonic Stem Cells/cytology , Mouse Embryonic Stem Cells/metabolism , Neural Stem Cells/cytology , Neural Stem Cells/metabolism , Phosphorylation , Point Mutation/genetics , Protein Binding , Transcription, Genetic
16.
Nat Commun ; 8(1): 2120, 2017 12 14.
Article in English | MEDLINE | ID: mdl-29242515

ABSTRACT

Regeneration-capable flatworms are informative research models to study the mechanisms of stem cell regulation, regeneration, and tissue patterning. However, the lack of transgenesis methods considerably hampers their wider use. Here we report development of a transgenesis method for Macrostomum lignano, a basal flatworm with excellent regeneration capacity. We demonstrate that microinjection of DNA constructs into fertilized one-cell stage eggs, followed by a low dose of irradiation, frequently results in random integration of the transgene in the genome and its stable transmission through the germline. To facilitate selection of promoter regions for transgenic reporters, we assembled and annotated the M. lignano genome, including genome-wide mapping of transcription start regions, and show its utility by generating multiple stable transgenic lines expressing fluorescent proteins under several tissue-specific promoters. The reported transgenesis method and annotated genome sequence will permit sophisticated genetic studies on stem cells and regeneration using M. lignano as a model organism.


Subject(s)
Gene Transfer Techniques , Genome, Helminth/genetics , Platyhelminths/genetics , Regeneration/genetics , Animals , Animals, Genetically Modified , Embryo, Nonmammalian/embryology , Embryo, Nonmammalian/metabolism , Female , Gene Expression Profiling , Gene Expression Regulation, Developmental , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Male , Organ Specificity/genetics , Ovary/metabolism , Platyhelminths/embryology , Platyhelminths/physiology , Promoter Regions, Genetic/genetics , Testis/metabolism , Transgenes/genetics
17.
Mol Cell ; 47(6): 954-69, 2012 Sep 28.
Article in English | MEDLINE | ID: mdl-22902557

ABSTRACT

In animal gonads, PIWI proteins and their bound 23-30 nt piRNAs guard genome integrity by the sequence specific silencing of transposons. Two branches of piRNA biogenesis, namely primary processing and ping-pong amplification, have been proposed. Despite an overall conceptual understanding of piRNA biogenesis, identity and/or function of the involved players are largely unknown. Here, we demonstrate an essential role for the female sterility gene shutdown in piRNA biology. Shutdown, an evolutionarily conserved cochaperone collaborates with Hsp90 during piRNA biogenesis, potentially at the loading step of RNAs into PIWI proteins. We demonstrate that Shutdown is essential for both primary and secondary piRNA populations in Drosophila. An extension of our study to previously described piRNA pathway members revealed three distinct groups of biogenesis factors. Together with data on how PIWI proteins are wired into primary and secondary processing, we propose a unified model for piRNA biogenesis.


Subject(s)
Argonaute Proteins/metabolism , Drosophila Proteins/metabolism , HSP90 Heat-Shock Proteins/metabolism , Molecular Chaperones/metabolism , RNA, Small Interfering/genetics , Animals , Cells, Cultured , DNA Transposable Elements , Drosophila Proteins/genetics , Drosophila melanogaster/genetics , Drosophila melanogaster/metabolism , RNA Interference , RNA, Small Interfering/metabolism
18.
EMBO J ; 30(19): 3977-93, 2011 Aug 23.
Article in English | MEDLINE | ID: mdl-21863019

ABSTRACT

PIWI proteins and their bound PIWI-interacting RNAs (piRNAs) form the core of a gonad-specific small RNA silencing pathway that protects the animal genome against the deleterious activity of transposable elements. Recent studies linked the piRNA pathway to TUDOR biology as TUDOR domains of various proteins bind symmetrically methylated Arginine residues in PIWI proteins. We systematically analysed the Drosophila TUDOR protein family and identified four previously not characterized TUDOR domain-containing proteins (CG4771, CG14303, CG11133 and CG31755) as essential piRNA pathway factors. We characterized CG4771 (Vreteno) in detail and demonstrate a critical role for this protein in primary piRNA biogenesis. Vreteno physically and/or genetically interacts with the primary pathway components Piwi, Armitage, Yb and Zucchini. Vreteno also interacts with the Tdrd12 orthologues CG11133 (Brother of Yb) and CG31755 (Sister of Yb), which are essential for the primary piRNA pathway in the germline and probably replace the function of the related but soma-specific factor Yb.


Subject(s)
Drosophila Proteins/metabolism , Membrane Transport Proteins/metabolism , Alleles , Animals , Crosses, Genetic , DNA Transposable Elements , Drosophila melanogaster , Female , Green Fluorescent Proteins/metabolism , Male , Ovary/metabolism , Protein Structure, Tertiary , RNA/metabolism , RNA Interference , RNA, Small Interfering/genetics
19.
EMBO J ; 29(19): 3301-17, 2010 Oct 06.
Article in English | MEDLINE | ID: mdl-20818334

ABSTRACT

In Drosophila, PIWI proteins and bound PIWI-interacting RNAs (piRNAs) form the core of a small RNA-mediated defense system against selfish genetic elements. Within germline cells, piRNAs are processed from piRNA clusters and transposons to be loaded into Piwi/Aubergine/AGO3 and a subset of piRNAs undergoes target-dependent amplification. In contrast, gonadal somatic support cells express only Piwi, lack signs of piRNA amplification and exhibit primary piRNA biogenesis from piRNA clusters. Neither piRNA processing/loading nor Piwi-mediated target silencing is understood at the genetic, cellular or molecular level. We developed an in vivo RNAi assay for the somatic piRNA pathway and identified the RNA helicase Armitage, the Tudor domain containing RNA helicase Yb and the putative nuclease Zucchini as essential factors for primary piRNA biogenesis. Lack of any of these proteins leads to transposon de-silencing, to a collapse in piRNA levels and to a failure in Piwi-nuclear accumulation. We show that Armitage and Yb interact physically and co-localize in cytoplasmic Yb bodies, which flank P bodies. Loss of Zucchini leads to an accumulation of Piwi and Armitage in Yb bodies, indicating that Yb bodies are sites of primary piRNA biogenesis.


Subject(s)
Drosophila Proteins/metabolism , Drosophila/genetics , Endoribonucleases/metabolism , Ovarian Follicle/metabolism , RNA Helicases/metabolism , RNA Interference , RNA, Small Interfering/biosynthesis , Active Transport, Cell Nucleus/physiology , Animals , Cells, Cultured , DNA Primers/genetics , DNA Transposable Elements/genetics , Female , Immunohistochemistry , Immunoprecipitation , Luciferases , Polymerase Chain Reaction
20.
EMBO J ; 29(10): 1688-98, 2010 May 19.
Article in English | MEDLINE | ID: mdl-20400939

ABSTRACT

MicroRNAs (miRNAs) have been implicated in cell-cycle regulation and in some cases shown to have a role in tissue growth control. Depletion of miRNAs was found to have an effect on tissue growth rates in the wing primordium of Drosophila, a highly proliferative epithelium. Dicer-1 (Dcr-1) is a double-stranded RNAseIII essential for miRNA biogenesis. Adult cells lacking dcr-1, or with reduced dcr-1 activity, were smaller than normal cells and gave rise to smaller wings. dcr-1 mutant cells showed evidence of being susceptible to competition by faster growing cells in vivo and the miRNA machinery was shown to promote G(1)-S transition. We present evidence that Dcr-1 acts by regulating the TRIM-NHL protein Mei-P26, which in turn regulates dMyc protein levels. Mei-P26 is a direct target of miRNAs, including the growth-promoting bantam miRNA. Thus, regulation of tissue growth by the miRNA pathway involves a double repression mechanism to control dMyc protein levels in a highly proliferative and growing epithelium.


Subject(s)
Drosophila Proteins/metabolism , MicroRNAs/metabolism , Proto-Oncogene Proteins c-myc/metabolism , RNA Helicases/metabolism , Ribonuclease III/metabolism , Animals , Cell Cycle , Cell Proliferation , Drosophila melanogaster , E2F Transcription Factors/metabolism , Epithelium/metabolism , Female , G1 Phase , Genotype , Male , Models, Biological , S Phase , Wings, Animal/metabolism
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