Biology subjects

Ferreira, J. C.

Publications and source records attributed to Ferreira, J. C..

7 recordsLinked to original sources

bioRxiv2026

Caloric Restriction Promotes Ischemia/Reperfusion Cardioprotection Through Increased Mitochondrial Na+/Ca2+ Exchange

Caloric restriction (CR) protects against cardiac ischemia/reperfusion (I/R) injury, but the underlying mechanisms remain incompletely understood. Since mitochondrial Ca2+ overload and redox imbalance is a major driver of cardiac damage during reperfusion, we investigated if enhanced mitochondrial Ca2+ efflux contributes toward CR-induced cardioprotection. Rats were subjected to 16 weeks of ad libitum (AL) feeding or 40% caloric restriction. CR significantly increased mitochondrial Ca2+ retention capacity when Na+ ions were present, reduced H2O2 release, and increased the expression of proteins related to mitochondrial Ca2+ extrusion. In cardiomyocytes exposed to serum from CR rats, Ca2+ retention capacity also markedly increased, as well as Ca2+ efflux and the expression of extrusion proteins NCLX and TMEM65. Following I/R, CR hearts exhibited improved functional recovery accompanied by enhanced retention and increased mitochondrial Ca2+ efflux activity, as well as reduced H2O2 release compared to AL controls. Inhibition of mitochondrial Na+/Ca2+ exchange abolished the mitochondrial adaptive effects of CR, eliminating its protection against damage in cardiomyocytes and perfused hearts. These findings demonstrate that CR protects the heart from I/R injury by enhancing CGP-sensitive Na+-dependent mitochondrial Ca2+ efflux, preserving mitochondrial function, limiting redox imbalance, and improving post-ischemic cardiac recovery.

biochemistry↗

bioRxiv2023

Discovery of Novel Allosteric Sites of SARS-CoV-2 Papain-Like Protease (PLpro)

Coronaviruses such as SARS-CoV-2 encode a conserved papain-like protease (PLpro) that is crucial for viral replication and immune evasion, making it a prime target for antiviral drug development. In this study, three surface pockets on SARS-CoV-2 PLpro that may function as sites for allosteric inhibition were computationally identified. To evaluate the effects of these pockets on proteolytic activity, 52 residues were separately mutated to alanine. In Pocket 1, located between the Ubl and thumb domains, the introduction of alanine at T10, D12, T54, Y72, or Y83 reduced PLpro activity to <12% of that of WT. In Pocket 2, situated at the interface of the thumb, fingers, and palm domains, Q237A, S239A, H275A, and S278A inactivated PLpro. Finally, introducing alanine at five residues in Pocket 3, between the fingers and palm domains, inactivated PLpro: S212, Y213, Y251, K254, and Y305. Pocket 1 has a higher druggability score than Pockets 2 and 3. MD simulations showed that interactions within and between domains play critical roles in PLpro activity and thermal stability. The essential residues in Pockets 1 and 2 participate in a combination of intra- and inter-domain interactions. By contrast, the essential residues in Pocket 3 predominantly participate in inter-domain interactions. The most promising targets for therapeutic development are Pockets 1 and 3, which have the highest druggability score and the largest number of essential residues, respectively. Non-competitive inhibitors targeting these pockets may be antiviral agents against COVID-19 and related coronaviruses.

biochemistry↗

bioRxiv2023

Cardiac Troponin I Directly Binds and Inhibits Mitochondrial ATP Synthase: a Noncanonical Role in the Post-Ischemic Heart

Cardiac troponin I (cTnI) is a sarcomeric protein critical to myocyte contraction. Unexpectedly, we found that some cTnI localized to the mitochondrial matrix in the heart, inhibited mitochondrial functions when stably expressed in non-cardiac cells and increased opening of the mitochondrial permeability transition pore under oxidative stress. Direct, specific, and saturable binding of cTnI to ATP synthase was demonstrated in vitro, using immune-captured ATP synthase, and in cells using proximity ligation assay. cTnI binding doubled F1F0 ATPase activity, whereas skeletal troponin I and several human mutant cTnI variants associated with familial hypertrophic cardiomyopathy did not. A rationally-designed ten amino acid peptide, P888, inhibited cTnI binding to ATP synthase, inhibited cTnI-induced increase in ATPase activity in vitro, and reduced cardiac injury following transient ischemia in vivo. We therefore suggest that mitochondria-associated cTnI may inhibit cardiac ATP synthase under basal conditions; pharmacological agents that release this inactivating effect of cTnI and thus preventing ATP hydrolysis during cardiac ischemia may increase the reservoir of functional mitochondria to reduce cardiac injury. Significance StatementCardiac troponin I (cTnI) is a key sarcomeric protein involved in the regulation of myocardial contractility. We found that some cTnI is present in the mitochondrial matrix where it binds to ATP synthase, disrupting mitochondrial function; inhibition of the cTnI-ATP synthase interaction with a selective peptide inhibitor reduces cardiac dysfunction following ischemia and reperfusion injury. Several pathogenic cTnI mutations associated with hypertrophic cardiomyopathy do not affect ATP synthase activity, suggesting a potential mechanism that contributes to the diverse pathologies associated with these mutations.

cell biology↗

bioRxiv2022

Hexokinase 1b is a novel target for non-small-cell lung cancer

Deregulation of glycolysis is common in non-small cell lung cancer (NSCLC). Hexokinase (HK) enzymes catalyze the phosphoryl-group-transfer in glucose metabolism. There are a very few studies that have begun to reveal the connections between glucose metabolism and splicing programs. Unlike HK2 gene, which is expressed as a single transcript, there are several transcripts of the HK1 gene due to alternative splicing. However, the functional differential roles of HK1 isoforms in glucose metabolism and tumor progression are still elusive. Here, we show that primary NSCLC patient tumor cells metabolically differ from the normal lung epithelium where they display predominant expression of one of the HK1 transcripts, hexokinase1b (HK1b). We utilized CRISPR-Cas9 system to selectively target specific HK1b isoform in NSCLC and show that silencing HK1b in NSCLC cells inhibits tumorigenesis through diminishing glycolysis and proliferation. Our findings constitute the first demonstration of the first biochemical distinction between the HK1 splice variants. Finally, HK1b deletion sensitizes NSCLC cells to standard-of-care, cisplatin treatment, and the combination therapy synergistically increases both apoptotic cell death by cisplatin and autophagic cell death by increased formation of LC3-II associated autophagic vesicles and myelinoid bodies. Notably, loss of HK1b leads to cellular DNA damage, further combination with cisplatin therapy showed significantly increased levels of DNA damage. Importantly, we showed that glycolysis and cisplatin resistance can be restored by adding-back HK1b in HK1b knock-out cells. Our findings reveal that targeting HK1b isoform alone or in combination with cisplatin may represent a novel strategy for NSCLC patients.

cancer biology↗

bioRxiv2022

Characterization of Arabian Peninsula whole exomes: exploring high inbreeding features

The exome (WES) capture enriched for UTRs on 90 Arabian Peninsula (AP) populations contributed nearly 20,000 new variants from a total over 145,000 total variants. Almost half of these variants were in UTR3, reflecting the low effort we have dedicated to cataloguing these regions, which can bear an important proportion of functional variants, as being discovered in genome-wide association studies. By applying several pathogenic predicting tools, we have demonstrated the high burden in potentially deleterious variants (especially in nonsynonymous and UTR variants located in genes that have been associated mainly with neurologic disease and congenital malformations) contained in AP WES, and the burden was as high as the consanguinity level (inferred as sum of runs of homozygosity, SROH) increased. Arabians had twice SROH values in relation to Europeans and East Asians, and within AP, Saudi Arabia had the highest values and Oman the lowest. We must pursuit cataloguing diversity in populations with high consanguinity, as the potentially pathogenic variants are not eliminated by genetic drift as much as in less consanguineous populations.

genetics↗

bioRxiv2021

Cannabidiol (CBD) repurposing as antibacterial: promising therapy of CBD plus polymyxin B against superbugs

Abstract Multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacteria are a major worldwide public health problem. In the last decades, resistance to last-resort antibiotics such as polymyxin B (PB) have been increasingly observed among these superbugs, compromising the effectiveness of antimicrobial therapy. The present study aimed (i) to assess the ultrapure Cannabidiol (CBD) antibacterial activity against a broad diversity of Gram-negative (GN) and Gram-positive (GP) bacteria (44 different species, 95 strains), comprising standard strains and clinical isolates, and (ii) to investigate the antibacterial activity of the combination CBD + PB against GN bacteria, including chromosomal- and plasmid-acquired PB-resistant and intrinsically PB-resistant GNB. We evaluated CBD in vitro antibacterial activity using the standard broth microdilution method, and the antibacterial activity of the combination CBD + PB was screened using the standard broth microdilution and confirmed by checkerboard assay. CBD exhibited antibacterial activity against different GP bacterial species, lipooligosaccharide (LOS)-expressing GN diplococcus (GND) (Neisseria gonorrhoeae, Neisseria meningitidis, and Moraxella catarrhalis), and Mycobacterium tuberculosis. The combination CBD + PB exhibited antibacterial activity against PB-resistant GNB (e.g., Klebsiella pneumoniae) as well as additive and/or synergistic effect against LOS-expressing GND. The antibacterial activity of the combination CBD + PB against Pseudomonas aeruginosa and plasmid-mediated colistin-resistant (MCR-1) E. coli strains could be only demonstrated in the presence of phenylalanine-arginine-{beta}-naphthylamide (PA{beta}N). In conclusion, our results show promising translational potential of the combination CBD + PB against MDR and XDR GNB, including PB-resistant K. pneumoniae, highlighting its potential as a rescue treatment for life-threatening infections caused by these superbugs. One Sentence SummaryPromising combination of cannabidiol (CBD) + polymyxin B (PB) against superbugs (e.g., PB-resistant Gram-negative bacilli): Repurposing CBD

microbiology↗

bioRxiv2021

Projecting ancient ancestry in modern-day Arabians and Iranians: a key role of the past exposed Arabo-Persian Gulf on human migrations

Arabian Peninsula is strategic for investigations centred on the structuring of the modern human population in the three main groups, in the awake of the out-of-Africa migration. Despite the poor climatic conditions for recovery of ancient DNA human evidence in Arabia, the availability of genomic data from neighbouring ancient specimens and of informative statistical tools allow better modelling the ancestry of these populations. We applied this approach to a dataset of 741,000 variants screened in 291 Arabians and 78 Iranians, and obtained insightful evidence. The west-east axis was a strong forcer of population structure in the Peninsula, and, more importantly, there were clear continuums throughout time linking west Arabia with Levant, and east Arabia with Iran and Caucasus. East Arabians also displayed the highest levels of the basal Eurasian lineage of all tested modern-day populations, a signal that was maintained even after correcting for possible bias due to recent sub-Saharan African input in their genomes. Not surprisingly, east Arabians were also the ones with higher similarity with Iberomaurusians, who were so far the best proxy for the basal Eurasians amongst the known ancient specimens. The basal Eurasian lineage is the signature of ancient non-Africans that diverged from the common European-East Asian pool before 50 thousand years ago, and before the later interbred with Neanderthals. Our results are strong evidence to include the exposed basin of the Arabo-Persian Gulf as possible home of basal Eurasians, to be investigated further on namely by searching ancient Arabian human specimens.

genetics↗