Abdalla Deiaa Mohamed Gamal Ahmed

All Publications

• Generation and characterization of a novel mouse model of Becker Muscular Dystrophy with a deletion of exons 52 to 55. Disease models & mechanisms Perillat, L. O., Wong, T. W., Maino, E., Ahmed, A., Scott, O., Hyatt, E., Delgado-Olguin, P., Visuvanathan, S., Ivakine, E. A., Cohn, R. D. 2024

  Abstract

  Becker Muscular Dystrophy (BMD) is a rare X-linked recessive neuromuscular disorder frequently caused by in-frame deletions in the DMD gene that result in the production of a truncated, yet functional, dystrophin protein. The consequences of BMD-causing in-frame deletions on the organism are difficult to predict, especially in regard to long-term prognosis. Here, we employed CRISPR-Cas9 to generate a new Dmd del52-55 mouse model by deleting exons 52-55, resulting in a BMD-like in-frame deletion. To delineate the long-term effects of this deletion, we studied these mice over 52 weeks by performing histology and echocardiography analyses and assessing motor functions. Our results suggest that a truncated dystrophin is sufficient to maintain wildtype-like muscle and heart histology and functions in young mice. However, the truncated protein appears insufficient to maintain normal muscle homeostasis and protect against exercise-induced damage at 52 weeks. To further delineate the effects of this exon52-55 in-frame deletion, we performed RNA-Seq pre- and post-exercise and identified several differentially expressed pathways that reflect the abnormal muscle phenotype observed at 52 weeks in the BMD model.

  View details for DOI 10.1242/dmm.050595

  View details for PubMedID 39099311

• Integrated small RNA, mRNA and protein omics reveal a miRNA network orchestrating metabolic maturation of the developing human heart BMC GENOMICS Aharon-Yariv, A., Wang, Y., Ahmed, A., Delgado-Olguin, P. 2023; 24 (1): 709

  Abstract

  As the fetal heart develops, cardiomyocyte proliferation potential decreases while fatty acid oxidative capacity increases in a highly regulated transition known as cardiac maturation. Small noncoding RNAs, such as microRNAs (miRNAs), contribute to the establishment and control of tissue-specific transcriptional programs. However, small RNA expression dynamics and genome-wide miRNA regulatory networks controlling maturation of the human fetal heart remain poorly understood.Transcriptome profiling of small RNAs revealed the temporal expression patterns of miRNA, piRNA, circRNA, snoRNA, snRNA and tRNA in the developing human heart between 8 and 19 weeks of gestation. Our analysis demonstrated that miRNAs were the most dynamically expressed small RNA species throughout mid-gestation. Cross-referencing differentially expressed miRNAs and mRNAs predicted 6200 mRNA targets, 2134 of which were upregulated and 4066 downregulated as gestation progressed. Moreover, we found that downregulated targets of upregulated miRNAs, including hsa-let-7b, miR-1-3p, miR-133a-3p, miR-143-3p, miR-499a-5p, and miR-30a-5p predominantly control cell cycle progression. In contrast, upregulated targets of downregulated miRNAs, including hsa-miR-1276, miR-183-5p, miR-1229-3p, miR-615-3p, miR-421, miR-200b-3p and miR-18a-3p, are linked to energy sensing and oxidative metabolism. Furthermore, integrating miRNA and mRNA profiles with proteomes and reporter metabolites revealed that proteins encoded in mRNA targets and their associated metabolites mediate fatty acid oxidation and are enriched as the heart develops.This study presents the first comprehensive analysis of the small RNAome of the maturing human fetal heart. Our findings suggest that coordinated activation and repression of miRNA expression throughout mid-gestation is essential to establish a dynamic miRNA-mRNA-protein network that decreases cardiomyocyte proliferation potential while increasing the oxidative capacity of the maturing human fetal heart. Our results provide novel insights into the molecular control of metabolic maturation of the human fetal heart.

  View details for DOI 10.1186/s12864-023-09801-8

  View details for Web of Science ID 001109107900003

  View details for PubMedID 37996818

  View details for PubMedCentralID PMC10668469

• Prevention of early-onset cardiomyopathy in Dmd exon 52-54 deletion mice by CRISPR-Cas9-mediated exon skipping. Molecular therapy. Methods & clinical development Rok, M., Wong, T. W., Maino, E., Ahmed, A., Yang, G., Hyatt, E., Lindsay, K., Fatehi, S., Marks, R., Delgado-Olguín, P., Ivakine, E. A., Cohn, R. D. 2023; 30: 246-258

  Abstract

  Duchenne muscular dystrophy (DMD) is a disease with a life-threatening trajectory resulting from mutations in the dystrophin gene, leading to degeneration of skeletal muscle and fibrosis of cardiac muscle. The overwhelming majority of mutations are multiexonic deletions. We previously established a dystrophic mouse model with deletion of exons 52-54 in Dmd that develops an early-onset cardiac phenotype similar to DMD patients. Here we employed CRISPR-Cas9 delivered intravenously by adeno-associated virus (AAV) vectors to restore functional dystrophin expression via excision or skipping of exon 55. Exon skipping with a solitary guide significantly improved editing outcomes and dystrophin recovery over dual guide excision. Some improvements to genomic and transcript editing levels were observed when the guide dose was enhanced, but dystrophin restoration did not improve considerably. Editing and dystrophin recovery were restricted primarily to cardiac tissue. Remarkably, our exon skipping approach completely prevented onset of the cardiac phenotype in treated mice up to 12 weeks. Thus, our results demonstrate that intravenous delivery of a single-cut CRISPR-Cas9-mediated exon skipping therapy can prevent heart dysfunction in DMD in vivo.

  View details for DOI 10.1016/j.omtm.2023.07.004

  View details for PubMedID 37545481

  View details for PubMedCentralID PMC10403712

• KDM8 epigenetically controls cardiac metabolism to prevent initiation of dilated cardiomyopathy. Nature cardiovascular research Ahmed, A., Syed, J. N., Chi, L., Wang, Y., Perez-Romero, C., Lee, D., Kocaqi, E., Caballero, A., Yang, J., Escalante-Covarrubias, Q., Ishimura, A., Suzuki, T., Aguilar-Arnal, L., Gonzales, G. B., Kim, K. H., Delgado-Olguín, P. 2023; 2 (2): 174-191

  Abstract

  Cardiac metabolism is deranged in heart failure, but underlying mechanisms remain unclear. Here, we show that lysine demethylase 8 (Kdm8) maintains an active mitochondrial gene network by repressing Tbx15, thus preventing dilated cardiomyopathy leading to lethal heart failure. Deletion of Kdm8 in mouse cardiomyocytes increased H3K36me2 with activation of Tbx15 and repression of target genes in the NAD+ pathway before dilated cardiomyopathy initiated. NAD+ supplementation prevented dilated cardiomyopathy in Kdm8 mutant mice, and TBX15 overexpression blunted NAD+-activated cardiomyocyte respiration. Furthermore, KDM8 was downregulated in human hearts affected by dilated cardiomyopathy, and higher TBX15 expression defines a subgroup of affected hearts with the strongest downregulation of genes encoding mitochondrial proteins. Thus, KDM8 represses TBX15 to maintain cardiac metabolism. Our results suggest that epigenetic dysregulation of metabolic gene networks initiates myocardium deterioration toward heart failure and could underlie heterogeneity of dilated cardiomyopathy.

  View details for DOI 10.1038/s44161-023-00214-0

  View details for PubMedID 38665902

  View details for PubMedCentralID PMC11041705

• Structure-Function Relationships of Human Milk Oligosaccharides on the Intestinal Epithelial Transcriptome in Caco-2 Cells and a Murine Model of Necrotizing Enterocolitis. Molecular nutrition & food research Wu, R. Y., Li, B., Horne, R. G., Ahmed, A., Lee, D., Robinson, S. C., Zhu, H., Cadete, M., Alganabi, M., Filler, R., Johnson-Henry, K. C., Delgado-Olguin, P., Pierro, A., Sherman, P. M. 2022; 66 (4): e2100893

  Abstract

  Necrotizing enterocolitis (NEC) is a devastating gastrointestinal emergency affecting preterm infants. Breastmilk protects against NEC, partly due to human milk oligosaccharides (HMOs). HMO compositions are highly diverse, and it is unclear if anti-NEC properties are specific to carbohydrate motifs. Here, this study compares intestinal epithelial transcriptomes of five synthetic HMOs (sHMOs) and examines structure-function relationships of HMOs on intestinal signaling.This study interrogates the transcriptome of Caco-2Bbe1 cells in response to five synthetic HMOs (sHMOs) using RNA sequencing: 2'-fucosyllactose (2'-FL), 3-fucosyllactose (3FL), 6'-siallyllactose (6'-SL), lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT). Protection against intestinal barrier dysfunction and inflammation occurred in an HMO-dependent manner. Each sHMO exerts a unique set of host transcriptome changes and modulated unique signaling pathways. There is clustering between HMOs bearing similar side chains, with little overlap in gene regulation which is shared by all sHMOs. Interestingly, most sHMOs protect pups against NEC, exerting divergent mechanisms on intestinal cell morphology and inflammation.These results demonstrate that while structurally distinct HMOs impact intestinal physiology, their mechanisms of action differ. This finding establishes the first structure-function relationship of HMOs in the context of intestinal cell signaling responses and offers a functional framework by which to screen and design HMO-like compounds.

  View details for DOI 10.1002/mnfr.202100893

  View details for PubMedID 34921749

• Treatment of necrotizing enterocolitis by conditioned medium derived from human amniotic fluid stem cells. PloS one O'Connell, J. S., Li, B., Zito, A., Ahmed, A., Cadete, M., Ganji, N., Lau, E., Alganabi, M., Farhat, N., Lee, C., Eaton, S., Mitchell, R., Ray, S., De Coppi, P., Patel, K., Pierro, A. 2021; 16 (12): e0260522

  Abstract

  Necrotizing enterocolitis (NEC) is one of the most distressing gastrointestinal emergencies affecting neonates. Amniotic fluid stem cells (AFSC) improve intestinal injury and survival in experimental NEC but are difficult to administer. In this study, we evaluated whether conditioned medium (CM) derived from human AFSC have protective effects.Three groups of C57BL/6 mice were studied: (i) breast-fed mice as control; (ii) experimental NEC mice receiving PBS; and (iii) experimental NEC mice receiving CM. NEC was induced between post-natal days P5 through P9 via: (A) gavage feeding of hyperosmolar formula four-time a day; (B) 10 minutes hypoxia prior to feeds; and (C) lipopolysaccharide administration on P6 and P7. Intra-peritoneal injections of either PBS or CM were given on P6 and P7. All mice were sacrificed on P9 and terminal ileum were harvested for analyses.CM treatment increased survival and reduced intestinal damage, decreased mucosal inflammation (IL-6; TNF-α), neutrophil infiltration (MPO), and apoptosis (CC3), and also restored angiogenesis (VEGF) in the ileum. Additionally, CM treated mice had increased levels of epithelial proliferation (Ki67) and stem cell activity (Olfm4; Lgr5) compared to NEC+PBS mice, showing restored intestinal regeneration and recovery during NEC induction. CM proteomic analysis of CM content identified peptides that regulated immune and stem cell activity.CM derived from human AFSC administered in experimental NEC exhibited various benefits including reduced intestinal injury and inflammation, increased enterocyte proliferation, and restored intestinal stem cell activity. This study provides the scientific basis for the use of CM derived from AFSC in neonates with NEC.

  View details for DOI 10.1371/journal.pone.0260522

  View details for PubMedID 34855833

  View details for PubMedCentralID PMC8638898

• Maternal obesity persistently alters cardiac progenitor gene expression and programs adult-onset heart disease susceptibility. Molecular metabolism Ahmed, A., Liang, M., Chi, L., Zhou, Y. Q., Sled, J. G., Wilson, M. D., Delgado-Olguín, P. 2021; 43: 101116

  Abstract

  Heart disease risk can be programmed by intrauterine exposure to obesity. Dysregulating key transcription factors in cardiac progenitors can cause subsequent adult-onset heart disease. In this study, we investigated the transcriptional pathways that are altered in the embryonic heart and linked to heart disease risk in offspring exposed to obesity during pregnancy.Female mice were fed an obesogenic diet and mated with males fed a control diet. Heart function and genome-wide gene expression were analyzed in adult offspring born to obese and lean mice at baseline and in response to stress. Cross-referencing with genes dysregulated genome-wide in cardiac progenitors from embryos of obese mice and human fetal hearts revealed the transcriptional events associated with adult-onset heart disease susceptibility.We found that adult mice born to obese mothers develop mild heart dysfunction consistent with early stages of disease. Accordingly, hearts of these mice dysregulated genes controlling extracellular matrix remodeling, metabolism, and TGF-β signaling, known to control heart disease progression. These pathways were already dysregulated in cardiac progenitors in embryos of obese mice. Moreover, in response to cardiovascular stress, the heart of adults born to obese dams developed exacerbated myocardial remodeling and excessively activated regulators of cell-extracellular matrix interactions but failed to activate metabolic regulators. Expression of developmentally regulated genes was altered in cardiac progenitors of embryos of obese mice and human hearts of fetuses of obese donors. Accordingly, the levels of Nkx2-5, a key regulator of heart development, inversely correlated with maternal body weight in mice. Furthermore, Nkx2-5 target genes were dysregulated in cardiac progenitors and persistently in adult hearts born to obese mice and human hearts from pregnancies affected by obesity.Obesity during pregnancy alters Nkx2-5-controlled transcription in differentiating cardiac progenitors and persistently in the adult heart, making the adult heart vulnerable to dysregulated stress responses.

  View details for DOI 10.1016/j.molmet.2020.101116

  View details for PubMedID 33212270

  View details for PubMedCentralID PMC7720025

• Human Milk Oligosaccharides Protect against Necrotizing Enterocolitis by Activating Intestinal Cell Differentiation. Molecular nutrition & food research Li, B., Wu, R. Y., Horne, R. G., Ahmed, A., Lee, D., Robinson, S. C., Zhu, H., Lee, C., Cadete, M., Johnson-Henry, K. C., Landberg, E., Alganabi, M., Abrahamsson, T., Delgado-Olguin, P., Pierro, A., Sherman, P. M. 2020; 64 (21): e2000519

  Abstract

  Necrotizing enterocolitis (NEC) is a devastating gastrointestinal emergency and currently the leading cause of mortality in preterm infants. Recent studies show that human milk oligosaccharides (HMOs) reduce the frequency and incidence of NEC; however, the molecular mechanisms for their protection are largely unexplored.To address this gap, a genome-wide profiling of the intestinal epithelial transcriptome in response to HMOs using RNA-sequencing is performed. It is found that HMOs alter the host transcriptome in 225 unique target genes pertaining to cell proliferation and differentiation, including upregulation of stem cell differentiation marker HMGCS2. To validate these results, differentiation in Caco-2Bbe1 (Caco-2) intestinal cells is verified by Alcian Blue staining and transepithelial electrical resistance (TER) recordings. Furthermore, an in vivo model of NEC is also employed whereby neonatal pups are gavage fed HMOs. Interestingly, HMOs-fed pups show enhanced cell MUC2 differentiation and HMGCS2 expression.These findings demonstrate HMOs protect against NEC in part by altering the differentiation of the crypt-villus axis. In addition, this study suggests that pooled HMOs directly induce a series of biological processes, which provide mechanistic insights to how HMOs protect the host intestine.

  View details for DOI 10.1002/mnfr.202000519

  View details for PubMedID 32926533

• A novel mouse model of Duchenne muscular dystrophy carrying a multi-exonic Dmd deletion exhibits progressive muscular dystrophy and early-onset cardiomyopathy. Disease models & mechanisms Wong, T. W., Ahmed, A., Yang, G., Maino, E., Steiman, S., Hyatt, E., Chan, P., Lindsay, K., Wong, N., Golebiowski, D., Schneider, J., Delgado-Olguín, P., Ivakine, E. A., Cohn, R. D. 2020; 13 (9)

  Abstract

  Duchenne muscular dystrophy (DMD) is a life-threatening neuromuscular disease caused by the lack of dystrophin, resulting in progressive muscle wasting and locomotor dysfunctions. By adulthood, almost all patients also develop cardiomyopathy, which is the primary cause of death in DMD. Although there has been extensive effort in creating animal models to study treatment strategies for DMD, most fail to recapitulate the complete skeletal and cardiac disease manifestations that are presented in affected patients. Here, we generated a mouse model mirroring a patient deletion mutation of exons 52-54 (Dmd Δ52-54). The Dmd Δ52-54 mutation led to the absence of dystrophin, resulting in progressive muscle deterioration with weakened muscle strength. Moreover, Dmd Δ52-54 mice present with early-onset hypertrophic cardiomyopathy, which is absent in current pre-clinical dystrophin-deficient mouse models. Therefore, Dmd Δ52-54 presents itself as an excellent pre-clinical model to evaluate the impact on skeletal and cardiac muscles for both mutation-dependent and -independent approaches.

  View details for DOI 10.1242/dmm.045369

  View details for PubMedID 32988972

  View details for PubMedCentralID PMC7522028

• Embryonic programming of heart disease in response to obesity during pregnancy. Biochimica et biophysica acta. Molecular basis of disease Ahmed, A., Delgado-Olguin, P. 2020; 1866 (2): 165402

  Abstract

  Obesity during pregnancy programs adult-onset heart disease in the offspring. Clinical studies indicate that exposure to an adverse environment in utero during early, as compared to late, gestation leads to a higher prevalence of adult-onset heart disease. This suggests that the early developing heart is particularly sensitive to an adverse environment. Accordingly, growing evidence from clinical studies and animal models demonstrates that obesity during pregnancy alters the function of the fetal heart, programming a higher risk of cardiovascular disease later in life. Moreover, gene expression patterns and signaling pathways that promote initiation and progression of cardiovascular disease are altered in the hearts in offspring born to obese mothers. However, the mechanisms mediating the long-term effects of an adverse environment in utero on the developing heart leading to adult-onset disease are not clear. Here, we review clinical and experimental evidence documenting the effects of maternal obesity during pregnancy on the fetal and post-natal heart and emphasize on the potential mechanisms of disease programming.

  View details for DOI 10.1016/j.bbadis.2019.01.028

  View details for PubMedID 30759362

• Formula feeding and immature gut microcirculation promote intestinal hypoxia, leading to necrotizing enterocolitis. Disease models & mechanisms Chen, Y., Koike, Y., Chi, L., Ahmed, A., Miyake, H., Li, B., Lee, C., Delgado-Olguín, P., Pierro, A. 2019; 12 (12)

  Abstract

  Major risk factors for necrotizing enterocolitis (NEC) are formula feeding and prematurity; however, their pathogenic mechanisms are unknown. Here, we found that insufficient arginine/nitric oxide synthesis limits blood flow in the intestinal microvasculature, leading to hypoxia, mucosal damage and NEC in the premature intestine after formula feeding. Formula feeding led to increased intestinal hypoxia in pups at postnatal day (P)1 and P5, but not in more mature pups at P9. Accordingly, blood flow in the intestinal microvasculature increased after formula feeding in P9 pups only. mRNA profiling revealed that regulators of arginine/nitric oxide synthesis are at higher levels in endothelial cells of the intestine in P9 than in P1 pups. Importantly, arginine supplementation increased intestinal microvasculature blood flow and prevented NEC, whereas an arginine antagonist exacerbated NEC. Our results suggest that balancing intestinal oxygen demand and supply in the premature intestine by modulating arginine/nitric oxide could be used to prevent NEC.This article has an associated First Person interview with the first author of the paper.

  View details for DOI 10.1242/dmm.040998

  View details for PubMedID 31704804

  View details for PubMedCentralID PMC6918740

• The transcriptional regulator CCCTC-binding factor limits oxidative stress in endothelial cells. The Journal of biological chemistry Roy, A. R., Ahmed, A., DiStefano, P. V., Chi, L., Khyzha, N., Galjart, N., Wilson, M. D., Fish, J. E., Delgado-Olguín, P. 2018; 293 (22): 8449-8461

  Abstract

  The CCCTC-binding factor (CTCF) is a versatile transcriptional regulator required for embryogenesis, but its function in vascular development or in diseases with a vascular component is poorly understood. Here, we found that endothelial Ctcf is essential for mouse vascular development and limits accumulation of reactive oxygen species (ROS). Conditional knockout of Ctcf in endothelial progenitors and their descendants affected embryonic growth, and caused lethality at embryonic day 10.5 because of defective yolk sac and placental vascular development. Analysis of global gene expression revealed Frataxin (Fxn), the gene mutated in Friedreich's ataxia (FRDA), as the most strongly down-regulated gene in Ctcf-deficient placental endothelial cells. Moreover, in vitro reporter assays showed that Ctcf activates the Fxn promoter in endothelial cells. ROS are known to accumulate in the endothelium of FRDA patients. Importantly, Ctcf deficiency induced ROS-mediated DNA damage in endothelial cells in vitro, and in placental endothelium in vivo Taken together, our findings indicate that Ctcf promotes vascular development and limits oxidative stress in endothelial cells. These results reveal a function for Ctcf in vascular development, and suggest a potential mechanism for endothelial dysfunction in FRDA.

  View details for DOI 10.1074/jbc.M117.814699

  View details for PubMedID 29610276

  View details for PubMedCentralID PMC5986204

• Isolating Embryonic Cardiac Progenitors and Cardiac Myocytes by Fluorescence-Activated Cell Sorting. Methods in molecular biology (Clifton, N.J.) Ahmed, A., Delgado-Olguin, P. 2018; 1752: 91-100

  Abstract

  Isolation of highly purified populations of embryonic cardiomyocytes enables the study of congenital cardiac phenotypes at the cellular level. Fluorescent-activated cell sorting (FACS) is normally used to isolate fluorescently tagged cells. Here we describe the isolation of differentiating mouse embryonic cardiac progenitors and cardiomyocytes at embryonic day (E) 9.5 and E13.5, respectively by FACS. Over 50,000 differentiating cardiac progenitors and 200,000 cardiomyocytes can be obtained in a single prep using the methods described.

  View details for DOI 10.1007/978-1-4939-7714-7_9

  View details for PubMedID 29564765

• Ezh2 is not required for cardiac regeneration in neonatal mice. PloS one Ahmed, A., Wang, T., Delgado-Olguin, P. 2018; 13 (2): e0192238

  Abstract

  The neonatal mouse heart has the remarkable capacity to regenerate lost myocardium within the first week of life. Neonatal cardiomyocytes re-express fetal genes that control cell proliferation after injury to promote regeneration. The loss of regenerative capacity of the heart one week after birth coincides with repression of a fetal transcriptional program coordinated by epigenetic regulators. The histone methyltransferase enhancer of zeste homolog 2 (Ezh2) is a repressor of fetal cardiac transcriptional programs and suppresses cardiomyocyte cell proliferation, suggesting a potential function in heart regeneration. However, it was recently demonstrated that Ezh2 is dispensable for heart regeneration in the neonatal heart. Here, we provide evidence supporting this finding and demonstrate that Ezh2 deficiency does not affect regeneration of the neonatal heart. We inactivated Ezh2 in differentiating embryonic cardiomyocytes, which led to depletion of histone H3 trimethylated at lysine 27 (H3K27me3). Ezh2 deficiency in cardiomyocytes did not affect clearance of the fibrotic scar in myocardial infarction (MI) and apical resection models of cardiac injury at post-natal day 1 (P1). Similarly, cardiomyocyte-specific loss of Ezh2 did not affect fibrotic scar size after MI or apical resection at P7, suggesting that it does not extend the regenerative time window. Our results demonstrate that Ezh2 is not required for innate neonatal cardiac regeneration.

  View details for DOI 10.1371/journal.pone.0192238

  View details for PubMedID 29466371

  View details for PubMedCentralID PMC5821314

• G9a controls placental vascular maturation by activating the Notch Pathway. Development (Cambridge, England) Chi, L., Ahmed, A., Roy, A. R., Vuong, S., Cahill, L. S., Caporiccio, L., Sled, J. G., Caniggia, I., Wilson, M. D., Delgado-Olguin, P. 2017; 144 (11): 1976-1987

  Abstract

  Defective fetoplacental vascular maturation causes intrauterine growth restriction (IUGR). A transcriptional switch initiates placental maturation, during which blood vessels elongate. However, the cellular mechanisms and regulatory pathways involved are unknown. We show that the histone methyltransferase G9a, also known as Ehmt2, activates the Notch pathway to promote placental vascular maturation. Placental vasculature from embryos with G9a-deficient endothelial progenitor cells failed to expand owing to decreased endothelial cell proliferation and increased trophoblast proliferation. Moreover, G9a deficiency altered the transcriptional switch initiating placental maturation and caused downregulation of Notch pathway effectors including Rbpj Importantly, Notch pathway activation in G9a-deficient endothelial progenitors extended embryonic life and rescued placental vascular expansion. Thus, G9a activates the Notch pathway to balance endothelial cell and trophoblast proliferation and coordinates the transcriptional switch controlling placental vascular maturation. Accordingly, G9A and RBPJ were downregulated in human placentae from IUGR-affected pregnancies, suggesting that G9a is an important regulator in placental diseases caused by defective vascular maturation.

  View details for DOI 10.1242/dev.148916

  View details for PubMedID 28455378

• RNA Silencing of Exocyst Genes in the Stigma Impairs the Acceptance of Compatible Pollen in Arabidopsis. Plant physiology Safavian, D., Zayed, Y., Indriolo, E., Chapman, L., Ahmed, A., Goring, D. R. 2015; 169 (4): 2526-38

  Abstract

  Initial pollen-pistil interactions in the Brassicaceae are regulated by rapid communication between pollen grains and stigmatic papillae and are fundamentally important, as they are the first step toward successful fertilization. The goal of this study was to examine the requirement of exocyst subunits, which function in docking secretory vesicles to sites of polarized secretion, in the context of pollen-pistil interactions. One of the exocyst subunit genes, EXO70A1, was previously identified as an essential factor in the stigma for the acceptance of compatible pollen in Arabidopsis (Arabidopsis thaliana) and Brassica napus. We hypothesized that EXO70A1, along with other exocyst subunits, functions in the Brassicaceae dry stigma to deliver cargo-bearing secretory vesicles to the stigmatic papillar plasma membrane, under the pollen attachment site, for pollen hydration and pollen tube entry. Here, we investigated the functions of exocyst complex genes encoding the remaining seven subunits, SECRETORY3 (SEC3), SEC5, SEC6, SEC8, SEC10, SEC15, and EXO84, in Arabidopsis stigmas following compatible pollinations. Stigma-specific RNA-silencing constructs were used to suppress the expression of each exocyst subunit individually. The early postpollination stages of pollen grain adhesion, pollen hydration, pollen tube penetration, seed set, and overall fertility were analyzed in the transgenic lines to evaluate the requirement of each exocyst subunit. Our findings provide comprehensive evidence that all eight exocyst subunits are necessary in the stigma for the acceptance of compatible pollen. Thus, this work implicates a fully functional exocyst complex as a component of the compatible pollen response pathway to promote pollen acceptance.

  View details for DOI 10.1104/pp.15.00635

  View details for PubMedID 26443677

  View details for PubMedCentralID PMC4677879

• Plasmacytoid variant of urothelial carcinoma: a report of a rare case. Pathology, research and practice Demellawy, D. E., Ahmed, A. D., Bora, B., Bonin, M. 2012; 208 (9): 561-4

  Abstract

  Plasmacytoid variant of urothelial bladder carcinoma is rare. We report a case with a detailed discussion of features that help characterize this variant. A 50-year-old man originally presented with gross hematuria. Resections at that time revealed a grade I-II superficial urothelial carcinoma. He did not return for follow-up until recently, three years later, when he presented with recurrent gross hematuria. An extensive tumor was identified on cystoscopy. Resection revealed a high-grade non-invasive papillary urothelial carcinoma. CT scan revealed a large urinary bladder solid mass with bilateral hydronephrosis. Metastatic workup was negative. The patient underwent a radical cystectomy with creation of ileal conduit. Final pathology revealed plasmacytoid variant of urothelial carcinoma with extensive vascular invasion and extension to the perivesical adipose tissue. We present a rare variant of urothelial carcinoma with comprehensive analysis of the morphological and immunophenotypic clues that characterize this variant.

  View details for DOI 10.1016/j.prp.2012.06.003

  View details for PubMedID 22854197

• Hemispheric extra-ventricular glioneurocytoma: a clinicopathological review with detailed immunohistochemical profile. Pathology, research and practice El Demellawy, D., Sur, M., Ahmed, A. D., Provias, J. 2012; 208 (8): 444-51

  Abstract

  Glioneuronal tumors have recently been recognized in the WHO Classification of Tumors of the Central Nervous System, 2007 [14]. However, the entities included in this category do not encompass all the glioneuronal tumors encountered during practice. We characterize a new entity called glioneurocytoma (GNC) showing distinct morphology with glial and neuronal differentiation. We reviewed 10 cases of glioneurocytomas diagnosed in our department during 2003 and 2004, with emphasis on clinicopathological features, immunohistochemical profile, genetic aberrations and prognosis. The cases included in the study showed equal gender distribution and age range of 23-40 years and mean age of 34.4 years at the time of initial presentation. Most of the tumors were centered in the frontal lobe. In our study, GFAP was the most sensitive and relatively specific marker for glial differentiation and remains the marker of choice for glial differentiation. CD56 and S100 protein were sensitive but non-specific. Vimentin, CD57 and NF were non-contributory in the immunohistochemical work up of glioneurocytomas. We concluded that the diagnosis of glioneurocytomas requires attention to morphological details and proper immunohistochemical assessment, using a panel of both glial and neuronal markers. Particular attention is recommended to the existence of the intermediate neurocytic cells which may be unique for these tumors. Future implication with full molecular analysis for gene expression profiling is suggested for proper and accurate identifying this entity.

  View details for DOI 10.1016/j.prp.2012.04.004

  View details for PubMedID 22710139