Biology subjects

Metwally, N. G.

Publications and source records attributed to Metwally, N. G..

3 recordsLinked to original sources

bioRxiv2024

Cytoadhesion of Plasmodium falciparum-infected red blood cells changes the expression of cytokine-, histone- and antiviral protein-encoding genes in brain endothelial cells

Malaria remains a significant global health problem, mainly due to Plasmodium falciparum, which is responsible for most fatal infections. Infected red blood cells (iRBCs) evade spleen clearance by adhering to endothelial cells (ECs), triggering capillary blockage, inflammation, endothelial dysfunction and altered vascular permeability, prompting an endothelial transcriptional response. The iRBCIT4var04/HBEC-5i model, where iRBCs present IT4var04 (VAR2CSA) on their surface, was used to analyse the effects of iRBC binding on ECs at different temperature (37{degrees}C vs. 40{degrees}C). Binding of non-infected RBCs (niRBCs) and fever alone altered the expression of hundreds of genes in ECs. Comparing the expression profile of HBEC-5i cells cultured either in the presence of iRBCs or in the presence of niRBCs revealed significant upregulation of genes linked to immune response, nucleosome assembly, NF-kappa B signaling, angiogenesis, and antiviral immune response/interferon-alpha/beta signaling. Raising the temperature to 40{degrees}C, simulating fever, led to further upregulation of many genes, particularly those involved in cytokine production and angiogenesis. In summary, the presence of iRBCs stimulates ECs, activating several immunological pathways and affecting antiviral (- parasitic) mechanisms and angiogenesis. Our data uncovered the induction of the interferon-alpha/beta signaling pathway in ECs in response to iRBCs.

microbiology↗

bioRxiv2023

Proteins differentially expressed between pathogenic and non-pathogenic Entamoeba histolytica clones influence pathogenicity by different mechanisms

Recently, two genes involved in pathogenicity in a mouse model of amoebic liver abscess were identified based on their differential expression between non-pathogenic (A1np) and pathogenic (B2p) clones of the Entamoeba histolytica isolate HM:1-IMSS. While overexpression of a gene encoding the metallopeptidase EhMP8-2 decreases the virulence of the pathogenic clone B2p, overexpression of the gene ehi_127670 (ehhp127), encoding a hypothetical protein, increases the virulence of the non-pathogenic clone A1np, while silencing this gene in B2p decreases virulence. To understand the role of both molecules in determining the pathogenicity of E. histolytica, silencing and overexpression transfectants were characterized in detail. Silencing of ehmp8-2, of the homologous gene ehmp8-1, or of both together in A1np trophozoites significantly altered the transcript levels of 60-350 genes. This strong change in the expression profile caused by the silencing of ehmp8-1 and/or ehmp8-2 implies that these peptidases regulate expression of numerous genes. Consequently, numerous phenotypic characteristics including cytopathic, hemolytic and cysteine peptidase activity were changed in response to their silencing. Silencing of ehhp127 in B2p trophozoites did not affect other genes, whereas overexpression in A1np trophozoites results in an altered expression of approximately 140 genes. EhHP127 appears to be important for trophozoite movement, as silencing negatively affects and overexpression positively affects trophozoite motility. Interestingly, the specific silencing of ehhp127 also impairs cytopathic activity, cysteine peptidase and hemolytic activity. All three molecules of interest, namely EhMP8-1, EhMP8-2, and EhHP127 can be detected in amoeba vesicles. Our results clearly show that the proteins studied here influence the pathogenicity of amoebae in different ways and use entirely different mechanisms to do so. Author summaryThe human pathogen Entamoeba histolytica can live asymptomatically in the intestine or become invasive and cause fatal liver abscesses. Approximately 15,000 people die each year as a result of an amoebic infection. Recently, two clones with different pathogenicity (A1np: non-pathogenic; B2p: pathogenic) derived from the E. histolytica isolate HM:1-IMSS were compared at the transcriptome level. Two highly differentially expressed genes (ehhp127 encoding a hypothetical protein and ehmp8-2 encoding a metallopeptidase) were identified. Analysis of E. histolytica transfectants showed that silencing of ehhp127 and overexpression of ehmp8-2 in B2p trophozoites reduced amoebic liver abscess formation in the mouse model. In this study, we characterized E. histolytica silencing and overexpression transfectants of ehmp8-2, as well as of the homologous gene ehmp8-1 and of ehhp127. It was shown that the altered expression of the metallopeptidase genes has a strong influence on the expression of a large number of genes and that the phenotype is strongly altered as a result. Silencing of ehhp127 does not affect the overall expression profile. However, specific silencing has a negative effect on motility, cysteine peptidase, hemolytic and cytopathic activity. All three molecules were shown to be localized in trophozoite vesicles.

cell biology↗

bioRxiv2021

An unusual trafficking domain in MSRP6 defines a complex needed for Maurer's clefts anchoring and maintenance in P. falciparum infected red blood cells

Intracellular malaria blood stage parasites remodel their host cell, a process essential for parasite survival and a cause of pathology in malaria infections. Host cell remodeling depends on the export of different classes of exported parasite proteins into the infected red blood cell (RBC). Here we show that members of a recently discovered group of difficult to predict exported proteins harbor an N-terminal export domain, similar to other classes of exported proteins, indicating that this is a common theme among all classes of exported proteins. For one such protein, MSRP6 (MSP-7 related protein 6), we identified a second, untypical export-mediating domain that corresponded to its MSP7-like region. In addition to its function in export, this domain also mediated attachment to the Maurers clefts, prominent parasite-induced structures in the host cell where MSRP6 is located. Using BioID with the Maurers clefts attachment domain of MSRP6 to identify interactors and compartment neighbors in live parasites we discovered a novel complex of proteins at the Maurers clefts. We show that this complex is necessary for the anchoring and maintaining the structural integrity of the Maurers clefts. The Maurers clefts are believed to be involved in the transport of the major virulence factor PfEMP1 to the host cell surface where it mediates cytoadherence of infected RBCs to endothelial cells, a main reason for the importance of host cell modifications for parasite virulence in the human host. Taking advantage of MSRP6 complex mutants and IT4 parasites that we modified to express only one specific PfEMP1 we find that abolishing Maurers clefts anchoring was neither needed for PfEMP1 transport to the host cell surface nor for cytoadherence. Altogether, this work reveals parasite proteins involved in Maurers clefts anchoring and maintenance and unexpectedly finds that these functions seem to be dispensable for virulence factor transport and surface display.

microbiology↗