Biology subjects

Robles, A.

Publications and source records attributed to Robles, A..

4 recordsLinked to original sources

bioRxiv2023

FASlpr gene dosage tunes the extent of lymphoproliferation and T cell differentiation in lupus

Sle1 and Faslpr are two lupus susceptibility loci that lead to manifestations of systemic lupus erythematosus. To evaluate dosage effects of FASlpr in determining cellular and serological phenotypes associated with lupus, we developed a new C57BL/6 (B6) congenic lupus strain, B6.Sle1/Sle1.Faslpr/+ (sle1homo.lprhet) and compared it with B6.Faslpr/lpr(lprhomo), B6.Sle1/Sle1 (sle1homo), and B6.Sle1/Sle1.Faslpr/lpr (sle1homo.lprhomo) strains. Whereas Sle1homo.lprhomo mice exhibited profound lymphoproliferation and early mortality, sle1homo.lprhet mice had a lifespan comparable to B6 mice, with no evidence of splenomegaly or lymphadenopathy. Compared to B6 monogenic lupus strains, sle1homo.lprhet mice exhibited significantly elevated serum anti-dsDNA antibodies and increased proteinuria. Additionally, Sle1homo.lprhet T cells had an increased propensity to differentiate into Th1 cells. Gene dose effects of Faslpr were noted in upregulating serum IL-1, IL-2, and IL-27. Taken together, sle1homo.lprhet mice emerge as a more faithful model of human SLE, ideal for genetic studies, autoantibody repertoire investigation, and for exploring Th1 effector cell skewing.

immunology↗

bioRxiv2022

Nanoscale dynamics of streptococcal adhesion to AGE-modified collagen

The adhesion of initial colonizers such as Streptococcus mutans to collagen is critical for dentinal and root caries progression. One of the most described pathological and aging-associated changes in collagen - including dentinal collagen - is the generation of advanced glycation end-products (AGEs) such as methylglyoxal (MGO)-derived AGEs. Despite previous reports suggesting that AGEs alter bacterial adhesion to collagen, the biophysics driving oral streptococcal attachment to MGO-modified collagen remains largely understudied. Thus, the aim of this work was to unravel the dynamics of the initial adhesion of S. mutans to type-I collagen in the presence and absence of MGO-derived AGEs, by employing bacterial cell force-spectroscopy with atomic force microscopy (AFM). Type-I collagen gels were treated with 10mM MGO to induce AGE formation, which was characterized with microscopy and ELISA. Subsequently, AFM cantilevers were functionalized with living S. mutans UA 159 or S. sanguinis SK 36 cells and probed against collagen surfaces to obtain force-curves displaying bacterial attachment in real-time, from which the adhesion force, number of events, Poisson analysis, and contour and rupture lengths for each individual detachment event were computed. Furthermore, in-silico docking studies between the relevant S. mutans UA 159 collagen-binding protein SpaP and collagen were computed, in the presence and absence of MGO. Overall, results showed that MGO modification increased both the number and adhesion force of single-unbinding events between S. mutans and collagen, without altering the contour or rupture lengths. Both experimental and in-silico simulations suggest that this effect is due to increased specific and non-specific forces and interactions between S. mutans UA 159 and MGO-modified collagen substrates. In summary, these results suggest that collagen alterations due to glycation and AGE formation may play a role in early bacterial adherence to oral tissues, associated with conditions such as aging or chronic hyperglycemia, amongst others.

microbiology↗

bioRxiv2022

DNA Double Strand Breaks cause chromosome loss through sister chromatid tethering in human embryos

Summary paragraphGenome editing by DNA double-strand breaks (DSB) is currently being investigated as a tool to treat or even prevent heritable diseases1. However, DNA repair mechanisms in the human embryo remain poorly understood and DSBs may result in chromosome loss 2,3. Here we provide evidence of whole and segmental chromosome loss in over one third of chromosomes 16, 17 and X targeted by CRISPR/Cas9-induced DNA DSB, including pericentromeric and mid-arm sites. Chromosomal changes were asymmetric relative to the Cas9 cut site: segmental losses occurred on both centric as well as acentric chromosome arms, while gains were exclusively found on acentric arms, suggesting that centromeres in broken chromosomes continued to mediate sister chromatid separation. Using this pattern of chromosomal errors, we were able to define new genomic coordinates of the active centromere on chromosome 16. Asymmetry was also found in the attrition of gDNA at the break site: attrition occurred centromeric of the DSB, while telomeric to the break, chromosomal ends were protected. Thus, spindle forces at centromeres and end tethering and protection at DSBs are antagonistic forces that interfere with accurate segregation of sister chromatids. Thereby, a single DSB is sufficient to result in the loss of a chromosome from the embryo. These results highlight the risks of aneuploidy in CRISPR/Cas9 genome editing, while also providing a mechanism for mitotically acquired aneuploidy caused by DNA breaks in human embryos.

developmental biology↗

bioRxiv2020

American mammals susceptibility to dengue according to geographical, environmental and phylogenetic distances

Many human emergent and re-emergent diseases have a sylvatic cycle. Yet, little effort has been put into discovering and modeling the wild mammal reservoirs of dengue (DENV), particularly in the Americas. Here, we show a species-level susceptibility prediction to dengue of wild mammals in the Americas as a function of the three most important biodiversity dimensions (ecological, geographical, and phylogenetic spaces), using machine learning protocols. Model predictions showed that different species of bats would be highly susceptible to DENV infections, where susceptibility mostly depended on phylogenetic relationships among hosts and their environmental requirement. Mammal species predicted as highly susceptible coincide with sets of species that have been reported infected in field studies, but it also suggests other species that have not been previously considered or that have been captured in low numbers. Also, the environment (i.e., the distance between the species optima in bioclimatic dimensions) in combination with geographic and phylogenetic distance is highly relevant in predicting susceptibility to DENV in wild mammals. Our results agree with previous modeling efforts indicating that temperature is an important factor determining DENV transmission, and provide novel insights regarding other relevant factors and the importance of considering wild reservoirs. This modeling framework will aid in the identification of potential DENV reservoirs for future surveillance efforts.

ecology↗