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result(s) for
"Nemer, Georges"
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Beauvericin potentiates the activity of pesticides by neutralizing the ATP-binding cassette transporters in arthropods
2021
Multi-drug resistance is posing major challenges in suppressing the population of pests. Many herbivores develop resistance, causing a prolonged survival after exposure to a previously effective pesticide. Consequently, resistant pests reduce the yield of agricultural production, causing significant economic losses and reducing food security. Therefore, overpowering resistance acquisition of crop pests is a must. The ATP binding cassette transporters (ABC transporters) are considered as the main participants to the pesticide efflux and their neutralization will greatly contribute to potentiate failed treatments. Real-Time PCR analysis of 19 ABC transporter genes belonging to the ABCB, ABCC, ABCG, and ABCH revealed that a broad range of efflux pumps is activated in response to the exposure to pesticides. In this study, we used beauvericin (BEA), a known ABC transporters modulator, to resensitize different strains of
Tetranychus urticae
after artificial selection for resistance to cyflumetofen, bifenazate, and abamectin. Our results showed that the combinatorial treatment of pesticide (manufacturer’s recommended doses) + BEA (sublethal doses: 0.15 mg/L) significantly suppressed the resistant populations of
T. urticae
when compared to single-drug treatments. Moreover, after selective pressure for 40 generations, the LC
50
values were significantly reduced from 36.5, 44.7, and 94.5 (pesticide) to 8.3, 12.5, and 23.4 (pesticide + BEA) for cyflumetofen, bifenazate, and abamectin, respectively. While the downstream targets for BEA are still elusive, we demonstrated hereby that it synergizes with sub-lethal doses of different pesticides and increases their effect by inhibiting ABC transporters. This is the first report to document such combinatorial activity of BEA against higher invertebrates paving the way for its usage in treating refractory cases of resistance to pesticides. Moreover, we demonstrated, for the first time, using in silico techniques, the higher affinity of BEA to ABC transformers subfamilies when compared to xenobiotics; thus, elucidating the pathway of the mycotoxin.
Journal Article
Thalidomide-Revisited: Are COVID-19 Patients Going to Be the Latest Victims of Yet Another Theoretical Drug-Repurposing?
by
Kamar, Amina
,
Nemer, Georges
,
Khalil, Athar
in
Animals
,
Anti-inflammatory agents
,
Anti-Inflammatory Agents, Non-Steroidal - therapeutic use
2020
The coronavirus disease 2019 (COVID-19) pandemic is a worldwide threatening health issue. The progression of this viral infection occurs in the airways of the lungs with an exaggerated inflammatory response referred to as the \"cytokine storm\" that can lead to lethal lung injuries. In the absence of an effective anti-viral molecule and until the formulation of a successful vaccine, anti-inflammatory drugs might offer a complementary tool for controlling the associated complications of COVID-19 and thus decreasing the subsequent fatalities. Drug repurposing for several molecules has emerged as a rapid temporary solution for COVID-19. Among these drugs is Thalidomide; a historically emblematic controversial molecule that harbors an FDA approval for treating erythema nodosum leprosum (ENL) and multiple myeloma (MM). Based on just one-case report that presented positive outcomes in a patient treated amongst others with Thalidomide, two clinical trials on the efficacy and safety of Thalidomide in treating severe respiratory complications in COVID-19 patients were registered. Yet, the absence of substantial evidence on Thalidomide usage in that context along with the discontinued studies on the efficiency of this drug in similar pulmonary diseases, might cause a significant obstacle for carrying out further clinical evaluations. Herein, we will discuss the theoretical effectiveness of Thalidomide in attenuating inflammatory complications that are encountered in COVID-19 patients while pinpointing the lack of the needed evidences to move forward with this drug.
Journal Article
Turicibacter and Catenibacterium as potential biomarkers in autism spectrum disorders
2024
Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by social, behavioral, and cognitive impairments. Several comorbidities, including gastrointestinal (GI) dysregulations, are frequently reported in ASD children. Although studies in animals have shown the crucial role of the microbiota in key aspects of neurodevelopment, there is currently no consensus on how the alteration of microbial composition affects the pathogenesis of ASD. Moreover, disruption of the gut–brain axis (GBA) has been reported in ASD although with limited studies conducted on the Mediterranean population. In our study, we aimed to investigate gut microbiota composition in Lebanese ASD subjects, their unaffected siblings, and a control group from various regions in Lebanon using the 16 S-rRNA sequencing (NGS). Our study revealed a lower abundance of
Turicibacter
and a significant enrichment on
Proteobacteria
in the ASD and siblings’ groups compared to the controls, indicating that gut microbiota is probably affected by dietary habits, living conditions together with host genetic factors. The study also showed evidence of changes in the gut microbiome of ASD children compared to their siblings and the unrelated control.
Bacteroidetes
revealed a lower abundance in the ASD group compared to controls and siblings, conversely,
Catenibacterium
and
Tenericutes
revealed an increased abundance in the ASD group. Notably, our study identifies alterations in the abundance of
Turicibacter
and
Catenibacterium
in ASD children suggesting a possible link between these bacterial taxa and ASD and contributing to the growing body of evidence linking the microbiome to ASD.
Journal Article
Mutational signatures in GATA3 transcription factor and its DNA binding domain that stimulate breast cancer and HDR syndrome
2021
Transcription factors (TFs) play important roles in many biochemical processes. Many human genetic disorders have been associated with mutations in the genes encoding these transcription factors, and so those mutations became targets for medications and drug design. In parallel, since many transcription factors act either as tumor suppressors or oncogenes, their mutations are mostly associated with cancer. In this perspective, we studied the
GATA3
transcription factor when bound to
DNA
in a crystal structure and assessed the effect of different mutations encountered in patients with different diseases and phenotypes. We generated all missense mutants of
GATA3
protein and DNA within the adjacent and the opposite
GATA3:DNA
complex models. We mutated every amino acid and studied the new binding of the complex after each mutation. Similarly, we did for every
DNA
base. We applied Poisson-Boltzmann electrostatic calculations feeding into free energy calculations. After analyzing our data, we identified amino acids and DNA bases keys for binding. Furthermore, we validated those findings against experimental genetic data. Our results are the first to propose in silico modeling for
GATA:DNA
bound complexes that could be used to score effects of missense mutations in other classes of transcription factors involved in common and genetic diseases.
Journal Article
Targeting ceramide metabolism to restore hypoxia-induced apoptosis in p53-deficient colon cancer cells
by
Fakhry, Maya
,
Younes, Hicham
,
Mechleb, Karen
in
Analysis
,
Apoptosis
,
Apoptosis - drug effects
2026
Hypoxic stress in solid tumors triggers growth arrest and apoptosis through p53 activation and stabilization. This environment inactivates p53 and drives the expansion of p53-mutant clones, which accentuate tumor aggressiveness. Ceramide, a signaling sphingolipid, was previously identified as a downstream collaborator with p53 in the stress-induced apoptosis and cell cycle arrest. Among sphingolipids, the balance between pro- and anti-apoptotic products, dictated by the expression and activity of appropriate enzymes, helps determine cell fate in response to hypoxia. The current study aimed to understand the role of ceramide in HCT116 human colon cancer cells response to hypoxia in the presence or absence of p53, and to determine whether the modulation of ceramide metabolism could sensitize the resistant p53-deficient cells to hypoxia-induced cell death. We observed that HCT116 p53-deficient cells were resistant to hypoxic cell death. We explored the role of ceramide in this response by screening for different sphingolipid metabolites through liquid-chromatography-mass spectrometry, and by measuring the expression of key enzymes involved in ceramide biosynthesis and breakdown. We also evaluated the changes in the cellular response to hypoxia associated with introduction of sphingolipid metabolites or with modulating the activity of related sphingolipid-metabolizing enzymes. In hypoxic p53-deficient cells, ceramide was synthesized via the de novo pathway through the action of ceramide synthases and dihydroceramide desaturase (DEGS1) driving the evasion of hypoxia-induced apoptosis. Among the accumulating ceramide species in p53 deficient cells, C24-ceramide was the most abundant and possibly contributing to their resistance. Tipping the sphingolipid balance in favor of pro-apoptotic sphingolipids, through the addition of C6 ceramide or sphingosine, or through the combined pharmacologic inhibition of DEGS1 and sphingosine kinase 1, helped circumvent the cellular resistance to hypoxia-induced apoptosis in cells lacking p53. Therefore, modulating sphingolipid metabolism may be a viable approach in the treatment of solid tumors with hypoxic regions.
Journal Article
Familial Hypercholesterolemia: The Lipids or the Genes?
by
Fahed, Akl C
,
Nemer, Georges M
in
Cardiovascular diseases
,
Care and treatment
,
Clinical Nutrition
2011
Familial Hypercholesterolemia (FH) is a common cause of premature cardiovascular disease and is often undiagnosed in young people. Although the disease is diagnosed clinically by high LDL cholesterol levels and family history, to date there are no single internationally accepted criteria for the diagnosis of FH. Several genes have been shown to be involved in FH; yet determining the implications of the different mutations on the phenotype remains a hard task. The polygenetic nature of FH is being enhanced by the discovery of new genes that serve as modifiers. Nevertheless, the picture is still unclear and many unknown genes contributing to the phenotype are most likely involved. Because of this evolving polygenetic nature, the diagnosis of FH by genetic testing is hampered by its cost and effectiveness.
In this review, we reconsider the clinical versus genetic nomenclature of FH in the literature. After we describe each of the genetic causes of FH, we summarize the known correlation with phenotypic measures so far for each genetic defect. We then discuss studies from different populations on the genetic and clinical diagnoses of FH to draw helpful conclusions on cost-effectiveness and suggestions for diagnosis.
Journal Article
Computational Applications: Beauvericin from a Mycotoxin into a Humanized Drug
by
Nemer, Nabil
,
Thoumi, Sergio
,
Rahy, Kelven
in
Animal models
,
Antimicrobial agents
,
Arthropods
2024
Drug discovery was initially attributed to coincidence or experimental research. Historically, the traditional approaches were complex, lengthy, and expensive, entailing costly random screening of synthesized compounds or natural products coupled with in vivo validation largely depending on the availability of appropriate animal models. Currently, in silico modeling has become a vital tool for drug discovery and repurposing. Molecular docking and dynamic simulations are being used to find the best match between a ligand and a molecule, an approach that could help predict the biomolecular interactions between the drug and the target host. Beauvericin (BEA) is an emerging mycotoxin produced by the entomopathogenic fungus Beauveria bassiana, being originally studied for its potential use as a pesticide. BEA is now considered a molecule of interest for its possible use in diverse biotechnological applications in the pharmaceutical industry and medicine. In this manuscript, we provide an overview of the repurposing of BEA as a potential therapeutic agent for multiple diseases. Furthermore, considerable emphasis is given to the fundamental role of in silico techniques to (i) further investigate the activity spectrum of BEA, a secondary metabolite, and (ii) elucidate its mode of action.
Journal Article
A HAND to TBX5 Explains the Link Between Thalidomide and Cardiac Diseases
2017
Congenital heart disease is the leading cause of death in the first year of life. Mutations only in few genes have been linked to some cases of CHD. Thalidomide was used by pregnant women for morning sickness but was removed from the market because it caused severe malformations including CHDs. We used both in silico docking software, and
in vitro
molecular and biochemical methods to document a novel interaction involving Thalidomide, TBX5, and HAND2. Thalidomide binds readily to TBX5 through amino acids R81, R82, and K226 all implicated in DNA binding. It reduces TBX5 binding to DNA by 40%, and suppresses TBX5 mediated activation of the NPPA and VEGF promoters by 70%. We documented a novel interaction between TBX5 and HAND2, and showed that a p.G202V HAND2 variant associated with CHD and coronary artery diseases found in a large Lebanese family with high consanguinity, drastically inhibited this interaction by 90%. Similarly, thalidomide inhibited the TBX5/HAND2 physical interaction, and the in silico docking revealed that the same amino acids involved in the interaction of TBX5 with DNA are also involved in its binding to HAND2. Our results establish a HAND2/TBX5 pathway implicated in heart development and diseases.
Journal Article
Deciphering the role of IL17RA in psoriasis and chronic mucocutaneous candidiasis: shared pathways and distinct manifestations
2025
Psoriasis and chronic mucocutaneous candidiasis (CMC), although distinct in their clinical manifestations, often coexist within specific patient cohorts. Despite this intriguing clinical observation, their genetic etiologies have been studied separately, neglecting the shared inflammatory mediator, interleukin 17A-F (IL17A-F). Consequently, the immunogenetic foundations underlying these conditions have remained enigmatic.
In this study, we analyzed the case of a 5-year-old female born to consanguineous parents who presented with concomitant psoriasis and CMC phenotypes. Utilizing whole exome and transcriptomic sequencing, we meticulously investigated the genetic underpinnings and molecular pathways underlying these complex pathologies. RNA sequencing was performed on a skin biopsy to confirm transcriptomic profiles associated with these conditions.
We identified a novel bi-allelic variant (NM_014339.6, c.1173C>G A) within the interleukin 17 receptor type A (IL17RA) gene, resulting in a premature stop codon (p. Tyr391Ter). Despite the truncation, our investigations revealed that this variant produces a fully functional IL17RA protein. This was evident from the presence of IL17RA in the patient's peripheral blood mononuclear cells (PBMCs) and the ability of the mutant IL17RA to dimerize with both wild-type protein and its partners IL17RC and IL17RD. Transcriptomic analysis of the skin biopsy showed a distinct psoriasis-associated signature intertwined with inflammatory pathways, including responses to fungal infections.
This report unveils an unprecedented genetic link serving as a common denominator for psoriasis and CMC. The novel IL17RA variant highlights the pivotal role of this receptor in the shared inflammatory pathways underlying these conditions. Our findings bridge a critical knowledge gap and provide insights into the molecular mechanisms connecting these diseases. This discovery not only advances our understanding of their pathophysiology but also lays the groundwork for personalized therapeutic strategies, heralding a new era of precision medicine for patients with intertwined psoriasis and CMC.
Journal Article
NKX2-5 Mutations in an Inbred Consanguineous Population: Genetic and Phenotypic Diversity
by
DePalma, Steven R.
,
Arabi, Mariam
,
Refaat, Marwan M.
in
45/23
,
631/208/1397
,
631/208/2489/144
2015
NKX2-5
mutations are associated with different forms of congenital heart disease. Despite the knowledge gained from molecular and animal studies, genotype-phenotype correlations in humans are limited by the lack of large cohorts and the incomplete assessment of family members. We hypothesized that studying the role of
NKX2-5
in inbred populations with homogeneous genetic backgrounds and high consanguinity rates such as Lebanon could help closing this gap. We sequenced
NKX2-5
in 188 index CHD cases (25 with ASD). Five variants (three segregated in families) were detected in eleven families including the previously documented p.R25C variant, which was found in seven patients from different families and in one healthy individual. In 3/5 familial dominant ASD cases, we identified an
NKX2-5
mutation. In addition to the heterogeneity of
NKX2-5
mutations, a diversity of phenotypes occurred within the families with predominant ASD and AV block. We did in fact identify a large prevalence of Sudden Cardiac Death (SCD) in families with truncating mutations and two patients with coronary sinus disease.
NKX2-5
is thus responsible for dominant familial ASD even in consanguineous populations and a wide genetic and phenotypic diversity is characteristic of
NKX2-5
mutations in the Lebanese population.
Journal Article