Biology subjects

Saiyed, T.

Publications and source records attributed to Saiyed, T..

3 recordsLinked to original sources

bioRxiv2021

Therapeutic role of Filarial HSP70 in murine models of polymicrobial sepsis and H1N1 Influenza

Nematodes characteristically modulate effector immune responses by synthesizing and releasing both anti-inflammatory as well as proinflammatory molecules in infected hosts. Pre-clinical studies suggest that immuno-modulatory molecules and synthetic small molecules that mimic parasite products could have therapeutic value to ameliorate tissue damage found in inflammatory diseases. We report here identification of a glycoprotein from filarial parasite, a homologue of mammalian Heat Shock Protein 70 with immunostimulatory attributes. The purified native glycoprotein designated as FHSP70 and its recombinant protein moiety, WFL were found to be TLR2 and TLR4 agonists in vitro in human myeloid cells and induce systemic inflammatory cytokines in vivo. Cecal ligation and puncture (CLP) performed in mice which leads to onset of poly microbial sepsis and mortality could be treated by therapeutic administration of a single dose of FHSP70, along with antibiotics, suggesting its potential as a immunotherapeutic adjuvant for clinical management of Sepsis. Intra-nasal administration of WFL to mice followed by challenge with virulent human Influenza-A virus resulted in decreased viral growth as well as improved survival. The protective effect was demonstrable by both prophylactic as well as therapeutic intranasal administration of WFL. Further, therapeutic administration of WFL by intraperitoneal route 5 days post viral challenge also resulted in significant decrease in viral load in the respiratory tract. One sentence SummarySystemic administration of a Filarial HSP70 acts as an adjuvant therapy, through immuno-modulation, for improved survival against murine Polymicrobial Sepsis and Viral Infection while its intra nasal administration protects mice prophylactically as well as therapeutically against H1N1 Influenza viral challenge.

immunology↗

bioRxiv2021

Inhibition of HIV-1 immune modulation by small molecules targeting viral Nef-host CD80 interface

HIV-1 causes diverse immunomodulatory responses in the host, including the down-regulation of co-stimulatory proteins CD80/86, mediated by HIV-1 protein Nef, blunting T-cell activation. Using a screening cascade of biochemical and cell-based assays, we identified potent small molecules representing three chemical scaffolds namely amino pyrimidine, phenoxy acetamide and bi-aryl heteroaryl carbamate which target the protein-protein interaction interface of CD80/86 and Nef with sub-micromolar potency. These molecules restore CD80/86 surface levels in HIV-1-Nef infected antigen presenting cells and T-cell activation. Nef-CD80 interface and small molecule binding sites were mapped by using computational docking and structural studies, followed by validation by mutational analysis. This analysis resulted in the identification of two key residues, K99 and R111, which were associated with down-modulation of CD80 surface levels by Nef and important for small molecule binding. Targeting these interacting residues disabled Nef-mediated down-modulation of CD80 surface levels, consequently restoring T-cell activation. Thus, we validate a new target, the Nef-CD80/86 protein-protein interaction interface, with a potential to develop new inhibitors to counteract the immunomodulatory consequences of HIV-1.

microbiology↗

bioRxiv2020

PDIP38 is a novel adaptor-like modulator of the mitochondrial AAA+ protease CLPXP

Polymerase {delta} interacting protein of 38 kDa (PDIP38) was originally identified in a yeast two hybrid screen as an interacting protein of DNA polymerase delta, more than a decade ago. Since this time several subcellular locations have been reported and hence its function remains controversial. Our current understanding of PDIP38 function has also been hampered by a lack of detailed biochemical or structural analysis of this protein. Here we show, that human PDIP38 is directed to the mitochondrion, where it resides in the matrix compartment, together with its partner protein CLPX. PDIP38 is a bifunctional protein, composed of two conserved domains separated by an -helical hinge region (or middle domain). The N-terminal (YccV-like) domain of PDIP38 forms an SH3-like {beta}-barrel, which interacts specifically with CLPX, via the adaptor docking loop within the N-terminal Zinc binding domain (ZBD) of CLPX. In contrast, the C-terminal (DUF525) domain forms an Immunoglobin-like {beta}-sandwich fold, which contains a highly conserved hydrophobic groove. Based on the physicochemical properties of this groove, we propose that PDIP38 is required for the recognition (and delivery to CLPXP) of proteins bearing specific hydrophobic degrons, potentially located at the termini of the target protein. Significantly, interaction with PDIP38 stabilizes the steady state levels of CLPX in vivo. Consistent with these data, PDIP38 inhibits the LONM-mediated turnover of CLPX in vitro. Collectively, our findings shed new light on the mechanistic and functional significance of PDIP38, indicating that in contrast to its initial identification as a nuclear protein, PIDP38 is a bona fide mitochondrial adaptor protein for the CLPXP protease.

biochemistry↗