Biology subjects

Sharif, M.

Publications and source records attributed to Sharif, M..

4 recordsLinked to original sources

bioRxiv2025

Cereblon Promotes Influenza Virus Replication through AMPK Ubiquitination

Influenza A and B viruses (IAV and IBV) continually threaten global health, with IAV posing a risk of emerging pandemics. Rapid viral evolution makes current treatments less effective, highlighting the urgent need for broad-spectrum antivirals. Targeting host factors essential for viral replication may offer a highly promising broad-spectrum antiviral strategy. In this context, cereblon (CRBN), a substrate adaptor of the CRL4 E3 ubiquitin ligase complex, is found to promote both IAV and IBV replication as a key pro-viral host factor. Mechanistically, CRBN targets and degrades AMP-activated protein kinase (AMPK) via the proteasome. This CRBN-driven degradation shifts the metabolism of the infected cells toward anabolism, promoting lipid droplet (LD) formation and creating a microenvironment favorable for viral replication. Genetic depletion or inhibition of CRBN stabilizes AMPK, significantly reduces LD formation, and effectively suppresses the replication of various IAV and IBV strains in vivo, demonstrating its broad-spectrum potential. Notably, Crbn knockout mice show marked resistance to lethal IAV infection. CRBN inhibition with immunomodulatory imide drugs--known CRBN inhibitors--significantly decreases IAV replication in vivo. This research underscores CRBN as a crucial regulator of host metabolism during viral infection, revealing the CRBN-AMPK axis as a promising target for host-directed pan-influenza antiviral development. Author SummaryInfluenza A and B viruses are response for recurring seasonal epidemics and occasional pandemics that pose serious global health challenges. Current antiviral drugs often lose effectiveness as influenza viruses rapidly develop resistance through genetic mutations. To overcome this limitation, our study focused on a host factor targeted by influenza viruses-the ubiquitin E3 ligase substrate adaptor cereblon (CRBN). We discovered that influenza viruses exploit CRBN to enhance their replication by altering host cell metabolism. Specifically, CRBN binds to a key energy sensor - AMPK and induces the ubiquitination and degradation of AMPK{gamma}. Consequently, the AMPK suppression shifts the cellular environment from catabolism to anabolism, activating lipogenic enzymes and promoting lipid droplets formation which provide a favorable environment for viral growth. Our study highlight that blocking CRBN either genetically or chemical inhibition (immunomodulatory imide drugs) of CRBN reduces LD formation and strongly suppresses diverse influenza strains replication in vitro and in vivo. These findings reveal not only how viruses hijack host metabolism via the CRBN-AMPK pathway but also present a potential therapeutic for novel broad-spectrum anti-influenza.

microbiology↗

bioRxiv2024

Multifunctional Roles of Sec13 Paralogues in the Euglenozoan Trypanosoma brucei

Secretory cargos are exported from the ER via COPII coated vesicles that have an inner matrix of Sec23/Sec24 heterotetramers and an outer cage of Sec13/Sec31 heterotetramers. In addition to COPII, Sec13 is part of the nuclear pore complex (NPC) and the regulatory SEA/GATOR complex in eukaryotes, which typically have one Sec13 orthologue. The kinetoplastid parasite Trypanosoma brucei has two paralogues: TbSec13.1, an accepted component of both COPII and the NPC, and TbSec13.2. Little is known about TbSec13.2, but others have proposed that it, and its orthologue in the distantly related diplonemid Paradiplonema papillatum, operate exclusively in the SEA/GATOR complex, and that this represents an evolutionary diversification of function unique to the euglenozoan protists (doi.org/10.1098/rsob.220364). Using RNAi silencing in trypanosomes we show both TbSec13s are essential. Knockdown of each dramatically and equally delays transport of GPI-anchored secretory cargo, indicating roles for both in COPII-mediated trafficking from the ER. Immunofluorescence and proximity labeling studies confirm that both TbSec13.1 and TbSec13.2 co-localize with TbSec24.1 to ER exit sites, and thus are functional components of the COPII machinery. Our findings indicate that TbSec13.2 function is not restricted to the SEA/GATOR complex in trypanosomes.

cell biology↗

bioRxiv2023

Diagnostic efficacy of hand-held digital refractometer for determining total serum protein in indigenous sheep of Pakistan

The study was designed to ascertain the diagnostic efficacy of hand-held digital refractometer in determining total protein. The Sipli sheep (n=141) were grouped as per gender (females=99, males=29) and age (G1=up till 1 year, G2=from 1 to 2 years, G3=above 2 years). The results regarding the overall mean ({+/-}SE) values and RIs for the TPs attained through serum chemistry analyzer (TP1) and hand-held digital refractometer (TP2) were non-significantly (P[≤]0.05) different (59.2{+/-}1.6g/L and 59.8{+/-}0.5g/L, respectively). However, the RIs were quite different between the two TPs being 45.1-95.7g/L and 57.0-67.0g/L for TP1 and TP2, respectively. Similar results were seen for gender-wise and group-wise results. On the contrary, the results regarding correlation coefficient and logilinear regression showed a negative correlation between the two TPs (r=-0.0244) with an adjusted r-square of 0.059 (5.9% probability). Furthermore, the results for Cronbach alpha and intraclass correlation coefficient between TP1 and TP2 showed that the values for single measure and average values were lower between TP1 and TP2 being - 0.135 and -0.313. Bland and Altman test between TP1 and TP2 also showed a weak level of agreement between the two methods of detecting TP. A proportional bias on the distribution of data around the mean difference line was noticed between TP1 and TP2 (Mean= 0.5; 95% CI= 39.8 to -40.9) with a standard deviation of biasness being 20.58. In a nutshell, the hand-held digital refractometer cannot be used as an on-farm POCT device for determining serum TP in sheep. However, certain other models of refractometers with higher sensitivity and specificity may be utilized in future studies to establish these conclusions for other species of livestock.

zoology↗

bioRxiv2017

MCE domain proteins: conserved inner membrane lipid-binding proteins required for outer membrane homeostasis

Bacterial proteins with MCE domains were first described as being important for Mammalian Cell Entry. More recent evidence suggests they are components of lipid ABC transporters. In Escherichia coli, the single-domain protein MlaD is known to be part of an inner membrane transporter that is important for maintenance of outer membrane lipid asymmetry. Here we describe two multi MCE domain-containing proteins in Escherichia coli, PqiB and YebT, the latter of which is an orthologue of MAM-7 that was previously reported to be an outer membrane protein. We show that all three MCE domain-containing proteins localise to the inner membrane. Bioinformatic analyses revealed that MCE domains are widely distributed across bacterial phyla but multi MCE domain-containing proteins evolved in Proteobacteria from single-domain proteins. Mutants defective in mlaD, pqiAB and yebST were shown to have distinct but partially overlapping phenotypes, but the primary functions of PqiB and YebT differ from MlaD. Complementing our previous findings that all three proteins bind phospholipids, results presented here indicate that multi-domain proteins evolved in Proteobacteria for specific functions in maintaining cell envelope homeostasis.

microbiology↗