Research square最新文献

{"title":"\"Trust and suspicion\" Client and provider perspectives on the acceptability of medication for opioid use disorder among people who inject drugs in Kampala, Uganda.","authors":"Peter Mudiope, Nicholas Nanyeenya, Okurut Simon, Adelline Twimukye, Kibira Simon, Mutamba Byamah Brian, Joan Nangendo, Stella Alamo, Fredrick Makumbi, Rhoda Wanyenze, Joseph Kb Matovu","doi":"10.21203/rs.3.rs-6819472/v1","DOIUrl":"10.21203/rs.3.rs-6819472/v1","url":null,"abstract":"<p><strong>Background: </strong>Despite strong evidence supporting medication for opioid use disorder (MOUD), acceptability varies considerably across contexts. This study explored client and provider perspectives on MOUD acceptability among people who inject drugs (PWID) in Kampala, Uganda.</p><p><strong>Methods: </strong>We conducted a qualitative descriptive study during November and December 2023 in Kampala Capital City, Uganda. In-depth interviews with 20 PWID (10 enrolled, 10 not enrolled) and key informant interviews with 10 MOUD service providers were conducted. Data were analysed using thematic analysis, guided by the Theoretical Framework of Acceptability (TFA) and managed with ATLAS.ti software.</p><p><strong>Results: </strong>MOUD was highly acceptable among providers, enrolled and non-enrolled participants. Facilitators included comprehensive, person-centered services that addressed health and psychosocial needs, supportive family relationships, alignment with personal recovery goals, and the safety and effectiveness of supervised medication therapy. However, participants encountered significant barriers. Structural challenges such as high transport costs, limited clinic operating hours, and strict enrolment criteria impeded access and continuity. Fear of arrest due to drug criminalization and stigma, both societal and within healthcare settings, further discouraged engagement. Additionally, some participants questioned methadone's effectiveness relative to heroin and reported widespread reliance on traditional and spiritual healing practices, often coerced by family members. Social norms promoting mutual drug-sharing as a symbol of trust were disrupted by MOUD enrolment, resulting in peer resistance and social isolation.</p><p><strong>Conclusion: </strong>MOUD was highly acceptable among PWID and providers in Uganda, valued for its effectiveness in restoring health and stability. However, structural barriers, stigma, misinformation, and restrictive enrolment often drove PWID to non-evidence-based treatment. Flexible service models, simplified enrolment procedures, community sensitisation, and collaboration with abstinence-based providers and law enforcement are vital to improving MOUD acceptability.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204361/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Super-resolution microscopy reveals distinct epigenetic states regulated by estrogen receptor activity.","authors":"Myles Brown, Tara Akhshi, Shengen Shawn Hu, Esme Wheeler, Christian Hellriegel, Douglas S Richardson, Nicole Cayting, Wangu Mvula, Buraq Ahmed, Rinath Jeselsohn, Chongzhi Zang","doi":"10.21203/rs.3.rs-6804567/v1","DOIUrl":"10.21203/rs.3.rs-6804567/v1","url":null,"abstract":"<p><p>Changes in gene expression regulated by ligand-dependent transcription factors such as estrogen receptor-α (ERα) involves the recruitment of coactivators including p300 that acetylates histone H3 at lysine 27 (H3K27ac). While H3K27ac marks active enhancers, the detailed chromatin architecture of enhancers remains unclear. Using super-resolution microscopy, we reveal distinct structural states of H3K27ac modified chromatin in response to ERα activation. In estradiol (E2)-treated cells, H3K27ac modified chromatin adopts open, elongated structures associated with active enhancers, while ERα inhibition induces compact, spherical H3K27ac modified chromatin conformations linked to repression. A constitutively active ERα mutation linked to endocrine therapy resistance in breast cancer maintains open chromatin states independent of ligand, suggesting sustained transcriptional activity. Our findings provide the first direct visualization of H3K27ac associated chromatin structural dynamics, challenging the assumption that H3K27ac modification alone is sufficient to lead to enhancer activation. By demonstrating that H3K27ac architecture is dynamically regulated by ERα, we establish a new paradigm for understanding epigenetic regulation and highlight potential therapeutic targets for endocrine therapy resistant cancers.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204369/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GenomePAM directs PAM characterization and engineering of CRISPR-Cas nucleases using mammalian genome repeats.","authors":"Zongli Zheng, Miao Yu, Limei Ai, Bang Wang, Shifeng Lian, James Liu, Linxian Li, Shengdar Tsai, Benjamin Kleinstiver, Lawrence Ip","doi":"10.21203/rs.3.rs-4552906/v1","DOIUrl":"10.21203/rs.3.rs-4552906/v1","url":null,"abstract":"<p><p>Characterizing the protospacer adjacent motif (PAM) requirements of different Cas enzymes is a bottleneck in the discovery of Cas proteins and their engineered variants in mammalian cell contexts. To overcome this challenge and to enable more scalable characterization of PAM preferences, we develop a method named GenomePAM that allows for direct PAM characterization in mammalian cells. GenomePAM leverages genomic repetitive sequences as target sites and does not require protein purification or synthetic oligos. GenomePAM uses a 20-nt protospacer that occurs ~16,942 times in every human diploid cell and is flanked by nearly random sequences. We demonstrate that GenomePAM can accurately characterize the PAM requirement of type II and type V nucleases, including the minimal PAM requirement of the near-PAMless SpRY and extended PAM for CjCas9. Beyond PAM characterization, GenomePAM allows for simultaneous comparison of activities and fidelities among different Cas nucleases on thousands of match and mismatch sites across the genome using a single gRNA and provides insight into the genome-wide chromatin accessibility profiles in different cell types.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204363/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Longitudinal pharmacokinetic and safety studies for dose optimization of a brain- penetrating erythropoietin for Alzheimer's disease.","authors":"Rudy Chang, Devaraj V Chandrashekar, G Chuli Roules, Nataraj Jagadeesan, Emi Iwasaki, Adenike Oyegbesan, Hayk Davtyan, Rachita K Sumbria","doi":"10.21203/rs.3.rs-6874797/v1","DOIUrl":"10.21203/rs.3.rs-6874797/v1","url":null,"abstract":"<p><strong>Background: </strong>Erythropoietin (EPO) is a potential therapeutic for Alzheimer's disease (AD), but has limited brain penetration, requiring high systemic doses that lead to hematopoietic side effects. To overcome this, EPO was conjugated with a transferrin receptor monoclonal antibody (TfRMAb) to enhance blood-brain barrier transport. This study assessed the pharmacokinetics (PK), safety, and efficacy of this modified EPO after repeated dosing in mice.</p><p><strong>Methods: </strong>For the PK and safety study, a multidose design was employed with 10-week-old C57 male mice (n=4-5/dose) receiving low (1 mg/kg), mid (3 and 6 mg/kg), or high (20 mg/kg) doses SQ for 4 weeks, aimed to evaluate the dose-dependent plasma concentrations and biodistribution, and metabolic and hematologic safety of the modified EPO. The dose that resulted in the highest safety and sustained plasma exposure was then dosed SQ to 5.5-month-old male APP_SAA KI mice (n=6) for 14 weeks. Controls included vehicle-treated APP_SAA KI and APP wild-type mice (n=4-5/group). The effect of modified EPO on Aβ load by immunoassays and spatial memory via the Y-maze test were assessed.</p><p><strong>Results: </strong>The 1 mg/kg dose showed no adverse effects and sustained brain and plasma exposure following repeated dosing, making it suitable for longitudinal treatment. Mid and high doses reduced plasma and brain exposure, and altered hematocrit, TfR expression, and spleen weight; changes that were largely reversible upon treatment cessation. Reduced plasma exposure at mid and high doses was not completely explained by increased TfR expression, anti-drug antibodies, tissue sequestration, or EPO receptor expression. Subsequently, 5.5-month-old APP_SAA KI mice received 1 mg/kg TfRMAb-EPO SQ for 14 weeks. Modified EPO significantly reduced brain Aβ load (70-80%, p<0.001) and aggregated Aβ (p<0.05), and improved spatial memory, indicated by a higher discrimination index in the Y maze test (p<0.05).</p><p><strong>Conclusions: </strong>With the advancement of TfRMAb-based therapeutics into clinical trials for AD, these findings are particularly significant. They offer essential preclinical data to guide dose optimization in longitudinal studies using TfRMAb-based therapeutics, specifically modified-EPO, and show the robust therapeutic potential of low-dose brain-penetrating EPO in the APP_SAA KI AD mouse model.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204373/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic coupling between folding correctors and the first of dimerized nucleotide binding domains in CFTR.","authors":"Guangyu Wang","doi":"10.21203/rs.3.rs-6890276/v1","DOIUrl":"10.21203/rs.3.rs-6890276/v1","url":null,"abstract":"<p><p>The most common cystic fibrosis mutation is the F508del mutation in the human cystic fibrosis transmembrane conductance regulator (hCFTR), which causes misfolding of the first of two nucleotide binding domains (NBD1/2), preventing Mg/ATP-dependent NBD dimerization for normal function. Although folding correctors elexacaftor/VX-445 and lumacaftor/VX-809 have been combined to correct the NBD1 misfolding, the exact correction pathway is still unknown. In this study, the constrained tertiary noncovalent interaction networks or the thermoring structures of dimerized NBD1 in hCFTR/E1371Q with or without F508del were analyzed to identify the weakest noncovalent bridge as the final posttranslational tertiary folding of dimerized NBD1 in response to folding correctors. These computational analyses suggested that hCFTR may primarily use cooperative folding between α- and β-subdomains in dimerized NBD1 as the last step upon the binding of the potentiator ivacaftor/VX-770. However, the binding of folding correctors may allosterically protect the α-subdomain from misfolding until subsequent core formation. This thermodynamic protective mechanism, unlike the chaperone-based one in cotranslational NBD1 folding, may restore posttranslational NBD1 folding for tight Mg/ATP-mediated NBD dimerization in the F508del mutation, and also potentially apply to treating other cystic fibrosis patients with rare mutations.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204354/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanistic Design of Cell-Penetrating Disruptors for a Phospho-Dependent Interaction.","authors":"Vanda Gunning, Matthew Batchelor, Krista K Alexander, Martin Walko, Selena G Burgess, Stephen J Royle, Eileen J Kennedy, Richard Bayliss","doi":"10.21203/rs.3.rs-6862805/v1","DOIUrl":"10.21203/rs.3.rs-6862805/v1","url":null,"abstract":"<p><p>The complex formed by transforming acidic coiled coil 3 (TACC3) and clathrin heavy chain (CHC) enhances mitotic spindle stability and strength by cross-linking microtubules. The interaction is dependent on phosphorylation of TACC3 at S558 by Aurora-A. Previously, we elucidated the structural basis of the TACC3/CHC interaction, which is driven by hydrophobic residues on both proteins and the formation of an α-helix in TACC3 that docks into the helical repeats of CHC. Here we find that this phosphorylation event plays an unusual role in the protein-protein interaction; rather than direct bond formation, the phosphorylated residue acts by overcoming an inherent electrostatic repulsion between K507 of CHC and basic residues in TACC3. Leveraging this insight, we optimized the sequence using peptide arrays to develop a hydrocarbon-stapled peptide (SP TACC3) that binds CHC with over a hundred-fold higher affinity than the parental TACC3 peptide, effectively disrupting the native interaction. The crystal structure of the SP TACC3/CHC complex reveals the basis for the enhanced interaction and highlights the contribution of additional polar and hydrophobic interactions. SP TACC3 efficiently penetrates cells and displaces TACC3 from the mitotic spindle, causing a delay in mitotic progression in two out of three cancer cell lines. This work showcases the novel application of hydrocarbon-stapled peptides to disrupt the TACC3/CHC protein-protein interaction in a cellular context, highlighting the potential of targeting this interface for future cancer therapies.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204359/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tuning the interaction of a ParA-type ATPase with its partner separates bacterial organelle positioning from partitioning.","authors":"Anthony Vecchiarelli, Jordan Byrne, Hema Swasthi, Longhua Hu, Christopher Azaldegui, Jian Liu","doi":"10.21203/rs.3.rs-6728214/v1","DOIUrl":"10.21203/rs.3.rs-6728214/v1","url":null,"abstract":"<p><p>The maintenance of carboxysome distribution (Mcd) system comprises the proteins McdA and McdB, which spatially organize carboxysomes to promote efficient carbon fixation and ensure their equal inheritance during cell division. McdA, a member of the ParA/MinD family of ATPases, forms dynamic gradients on the nucleoid that position McdB-bound carboxysomes. McdB belongs to a widespread but poorly characterized class of ParA/MinD partner proteins, and the molecular basis of its interaction with McdA remains unclear. Here, we demonstrate that the N-terminal 20 residues of <i>H. neapolitanus</i> McdB are both necessary and sufficient for interaction with McdA. Within this region, we identify three lysine residues whose individual substitution modulates McdA binding and leads to distinct carboxysome organization phenotypes. Notably, lysine 7 (K7) is critical for McdA interaction: substitutions at this site result in the formation of a single carboxysome aggregate positioned at mid-nucleoid. This phenotype contrasts with that of an McdB deletion, in which carboxysome aggregates lose their nucleoid association and become sequestered at the cell poles. These findings suggest that weakened McdA-McdB interactions are sufficient to maintain carboxysome aggregates on the nucleoid but inadequate for partitioning individual carboxysomes across it. We propose that, within the ParA/MinD family of ATPases, cargo positioning and partitioning are mechanistically separable: weak interactions with the cognate partner can mediate positioning, whereas effective partitioning requires stronger interactions capable of overcoming cargo self-association forces.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204374/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fixel-Based Analysis Reveals Detailed White Matter Changes in Semantic Dementia.","authors":"Maria Luisa Mandelli, Yann Cobigo, Ilaria Perretti, Dana Leichter, Celina Alba, Rian Bogley, Nick Wellman, Siddarth Ramkrishnan, Zachary A Miller, Bruce L Miller, William W Seeley, Howard J Rosen, Maria Luisa Gorno-Tempini","doi":"10.21203/rs.3.rs-6874132/v1","DOIUrl":"10.21203/rs.3.rs-6874132/v1","url":null,"abstract":"<p><strong>Background and purpose: </strong>Accurately characterizing white matter (WM) microstructure is critical for understanding neurodegenerative diseases such as semantic dementia (SD). Regionally constrained techniques like tract-based spatial statistics (TBSS) rely on diffusion-tensor imaging (DTI) and assume a single fiber population per voxel, limiting their sensitivity to complex architecture. Fixel-based morphometry (FBM) overcomes this by assessing multiple fiber populations (fixels) within a single voxel. In this study, we compared TBSS and Fixel-based analysis (FBA) for detecting WM alterations in SD variants associated with anterior temporal lobe (ATL) atrophy.</p><p><strong>Methods: </strong>Multi-shell diffusion MRI from 16 left-lateralized semantic-variant PPA (svPPA) and 15 right-lateralized semantic-behavioral fronto-temporal dementia (sbvFTD) cases, plus 44 neurologically healthy controls, underwent both TBSS-DTI and whole-brain FBA. Fiber-specific metrics of fiber density and cross-section were contrasted with conventional DTI measures.</p><p><strong>Results: </strong>Both methods confirmed damage to ATL-connected tracts-the uncinate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and temporal projections of the arcuate fasciculus. FBA, however, revealed additional involvement of juxtacortical and other previously overlooked pathways, including the tapetum and anterior commissure, projections to the parahippocampal gyrus and amygdala, and longer-range parietal connections.</p><p><strong>Conclusions: </strong>By capturing fiber-specific micro- and macrostructural changes, FBA yields a more comprehensive map of WM degeneration in SD than TBSS. The ability to detect early alterations in commissural and mesial-temporal pathways refines our understanding of disease spread and highlights candidate targets for monitoring and intervention aimed at preserving cognitive function.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204362/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beyond the Headache: Autonomic Reflex Dysfunction and Sensory Hypersensitivity Contribute to Orthostatic Intolerance in Migraine.","authors":"Bridget R Mueller, Maya Campbell, Jihan Grant, Jasmin Jean, Marianna Vinokur, Michael Kaplan, Daniel Clauw, Jessica Robinson-Papp","doi":"10.21203/rs.3.rs-6847469/v1","DOIUrl":"10.21203/rs.3.rs-6847469/v1","url":null,"abstract":"<p><strong>Objective: </strong>We sought to determine: 1.) the relationship between headache frequency and autonomic reflexes, and 2.) mechanisms underlying orthostatic intolerance (OI) in patients with migraine.</p><p><strong>Methods: </strong>Adults with migraine (N = 30) underwent autonomic function tests summarized as the Composite Autonomic Severity Score (CASS) and vagal/adrenergic baroreflex sensitivity (BRS-V/A). Postural Orthostatic Tachycardia Syndrome (POTS) and orthostatic hypotension/hypertension were diagnosed during tilt table testing. A cold pressor test (CPT) evaluated sympathetic vasomotor function. Participants completed the Migraine Disability Assessment (MIDAS), the 2011 Fibromyalgia (FM) Survey Criteria, chronic overlapping pain condition (COPC) screener, and Compass-31.</p><p><strong>Results: </strong>Monthly headache days correlated with CASS (p = 0.001), BRS-V (p < 0.001), and the systolic blood pressure response to CPT (p = 0.003) in the expected direction with increasing ANS reflex dysfunction correlating to increasing number of headache days. During tilt testing, OI was prevalent (25/30; 83%) and reported by all patients with chronic migraine. An abnormal cardiovascular response to tilt was present in the majority (63%) of which POTS was the most common etiology (56.2%). Patients reporting OI during tilt table testing despite a <i>normal</i> cardiovascular response (33%) had higher FM scores (15.8 ± 3.6 vs. 7.5 ± 4.6; p < 0.01) and a greater prevalence of non-headache COPCs (88.8% versus 20.0%, p = 0.02), compared to participants who were asymptomatic during tilt.</p><p><strong>Conclusions: </strong>There are two etiologies of OI in patients with migraine: 1.) an abnormal cardiovascular response to tilt (concordant OI) and, 2.) sensory hypersensitivity (discordant OI).</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204353/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regulatory Role of Serine59 in the Oligomeric Dynamics and Chaperone Function of αB-Crystallin.","authors":"Tenzin Tender, Puttur Santhoshkumar, Leena Suleiman, Md Rejaul Hoq, K Krishna Sharma","doi":"10.21203/rs.3.rs-6787013/v1","DOIUrl":"10.21203/rs.3.rs-6787013/v1","url":null,"abstract":"<p><p>We previously demonstrated that deletion of the ₅₄FLRAPSW₆₁ sequence, containing the key phosphorylation site Serine 59 (S59), resulted in a two-fold reduction in oligomeric mass and a ten-fold enhancement of αB-crystallin's chaperone activity. This study examined whether targeted deletion (ΔS59) or phosphomimetic substitution (S59D) of S59 could replicate these effects. Using MALS analysis, we found that the average oligomeric mass decreased from 579 kDa in the wild type (αB-WT) to 556 kDa in ΔS59 and 434 kDa in S59D. Interestingly, the S59A variant had an increased mass of 611 kDa. All variants retained their chaperone function, but their efficiencies varied significantly. Specifically, S59D formed smaller, more polydisperse complexes that effectively suppressed aggregation when interacting with rapidly aggregating substrates. In contrast, ΔS59 and S59A created stable complexes with lysozyme, reducing precipitation and aggregate size. Zeta potential measurements indicated distinct surface charge profiles among the variants, but there was no clear correlation between these charges and their chaperone efficiency. Additionally, cytotoxicity assays conducted on ARPE-19 cells under oxidative stress showed that all S59 variants exhibited comparable protective effects against cell death relative to αB-WT. These results indicate that while S59 is not essential for oligomer formation or chaperone function, it plays an important role in modulating oligomer size and interactions with different substrates. Notably, the effects of S59D were measurable but did not replicate the enhanced functionality observed with the complete deletion of the 54-61 motif, reinforcing the significance of the N-terminal region.</p>","PeriodicalId":519972,"journal":{"name":"Research square","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12204343/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144532619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}