Biology subjects

Azevedo, M. M.

Publications and source records attributed to Azevedo, M. M..

5 recordsLinked to original sources

bioRxiv2025

Mechanisms shaping the transcriptome of E. coli to non-lethal rifampicin stress

Rifampicin, by hampering transcription, perturbs bacteria even at non-lethal concentrations. In response, Escherichia coli adapts its phenotype to minimize mortality, which is followed by beneficial mutations. Most genome-wide transcriptional regulatory mechanisms controlling the adaptations remain unidentified. We studied the genome-wide, time-resolved, transcriptional program of susceptible E. coli cells under non-lethal rifampicin stress. Dynamically, the transcriptome widely diverged from the control, but later partially realigned. The mechanisms were changes in RNAP and Gyrase levels, promoter sequences, transcription factor network, intergenic distance, sensitivity to DNA supercoiling buildup, {sigma} factor specificity, (p)ppGpp, and a few global regulators. These results show that the genome-wide response dynamics to rifampicin is influenced by the structure of the gene regulatory network. Next, we compared the evolutionarily distant pathogen Mycobacterium tuberculosis. In both species, adjacent genes on the DNA exhibited similar response strengths. Also, the response strengths of orthologous genes were correlated, suggesting that both species implement similar (likely beneficial) phenotypic adaptations. In support, E. coli orthologs were enriched in the mechanisms identified as influential. Overall, E. coli, and likely other bacteria, have mechanisms influencing specific gene cohort responses to non-lethal rifampicin stress, which likely enhances survivability, thus facilitating the emergence of resistance.

systems biology↗

bioRxiv2025

Embryonic Spinocerebellar Ataxia Type 37 AUUUC Repeat RNA Causes Neurodevelopmental Defects in Zebrafish

Onset of many neurodegenerative and neuromuscular diseases usually starts in adulthood; however, recent advances point toward neurodevelopmental changes as drivers of late neurodegeneration. How early neuropathological features occur in these conditions remains unclear, which is critical for timely therapeutic intervention. Here, we provide evidence that neurodevelopmental axonal defects initiate a motor phenotype in a zebrafish model of spinocerebellar ataxia type 37 (SCA37), a degenerative hereditary condition caused by an ATTTC repeat in the DAB1 gene. We investigated neuronal defects triggered by the embryonic AUUUC repeat RNA and their effects later in life by transiently expressing this RNA in embryos and analyzing innervation and motor function. We found abnormalities in motor neuron axonal outgrowth and muscle innervation. We also discovered disrupted embryonic motor activity and reduced locomotor distance and velocity in late adult zebrafish, demonstrating motor impairment. Moreover, we showed that NOVA2 expression rescues axonal defects, indicating dysfunction of NOVA2-regulated neurodevelopmental processes. Overall, our results establish embryonic expression of the AUUUC repeat RNA as a driver of axonal and synaptic abnormalities, interfering with neuronal circuits and culminating in adult motor dysfunction.

neuroscience↗

bioRxiv2025

A transient mechanical crosstalk between Adherens Junctions and Focal Adhesions sustains cell proliferation in premalignant breast epithelial cells

The weakening of Adherens Junctions (AJs) and Focal Adhesions (FAs) adhesiveness has been proposed to enable the initiation and progression of several types of cancer. Here we report that, prior to disassembling AJs and acquiring malignant traits, premalignant mammary epithelial cells overactivating the Src proto-oncogene transiently enhance tensile forces at both AJs and FAs, thereby gaining a proliferative advantage. We show that AJs and FAs are transiently under higher tensile forces in premalignant Src-activated cells. Cells unable to increase tensile forces at FAs by knocking down PXN or inhibiting FAK activity fail to transiently build up tensile force at AJs and to grow. Conversely, preventing AJ strengthening using EGTA or small interference RNA against P-cadherin suppresses the transient increase in tensile forces at FAs, EGFR-ERK and MRTF-A-SRF activation and cell proliferation. Moreover, knocking down E-cadherin, the sole classical cadherin in Drosophila, inhibits Src-induce tissue overgrowth in vivo. Thus, prior to the loss of cell-cell and cell-matrix adhesiveness, strengthening of AJs and FAs may be an essential early step for mammary cells to gain a proliferative advantage and establish the mechanical and signaling conditions necessary for subsequent malignant transformation. Statement of SignificanceAlthough the weakening of cell-cell and cell-matrix adhesiveness is commonly associated with cancer initiation and progression, our findings reveal that an initial increase in adhesiveness enables proliferation and malignant progression.

cancer biology↗

bioRxiv2025

The Insertion of an ATTTC Repeat in an Alu Element Hyperactivates a Primate-Specific Neurodevelopmental Enhancer in Spinocerebellar Ataxia Type 37

Alu are evolutionarily very old primate-specific interspersed repeat elements that constitute [~]11% of the human genome. They are a source of short tandem repeats (STRs), which often expand in size and originate inherited neuromuscular and neurodegenerative disorders. How expanded STR insertion mutations within Alu STRs culminate in disease remains unknown. Here we report an Alu STR located in an intron of DAB1 that functions as a neurodevelopmental enhancer. We demonstrated that an ATTTC repeat insertion in this DAB1 Alu STR, known to cause spinocerebellar ataxia type 37 (SCA37), hyperactivates a neurodevelopmental DAB1 enhancer. Importantly, we showed that neurons derived from SCA37 subjects have higher levels of DAB1 expression and DAB1 overexpression causes abnormal axonal pathfinding in vivo. Overall, these results establish that neuronal dysregulation of a developmental DAB1 Alu STR enhancer contributes to SCA37 pathogenesis, an unexplored mechanism likely acting in many Alu STR diseases, potentially reshaping the therapeutic landscape.

genetics↗

bioRxiv2021

The proteome of remyelination is different from that of developmental myelination

Loss of myelin underlies the pathology of several neurological disorders of diverse etiology. CNS remyelination by adult oligodendrocyte progenitor cells (OPCs) can occur but it differs from developmental myelination carried out by neonatal OPCs. We asked whether the myelin proteome of remyelinated regions is changed. We compared the myelin proteome formed during development to the remyelination proteome attained after lysolecithin-induced demyelination in the mouse spinal cord. Mass-spectrometry analysis of iTRAQ labelled myelin protein lysates showed that the proteome of remyelination is different from that of developmental myelination, leading to profound changes in myelin protein content. Aside from known mediators of oligodendrocyte differentiation, we found proteome alterations included modulators of metabolism, cell signaling and actin cytoskeleton dynamics. Downregulating one candidate (FSCN1/Fascin1) was sufficient to partially hamper oligodendrocytes in-vitro. In summary, we identify the difference in the proteome of remyelinating oligodendrocytes as a novel potential contributor to the pathophysiology of demyelinating disorders, thus providing new potential therapeutic targets for future studies.

neuroscience↗