Percorrer por autor "Barros, Patricia"
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- Dissecting the impact of SHC-1 inhibitors in enhancing the plasma membrane abundance of the CFTR channel across epithelial cell modelsPublication . Barros, Patricia; Pereira, Mariana F.L.; Tomilov, Alexey; Cortopassi, Gino; Jordan, Peter; Matos, PauloPlasma membrane (PM) ion transport depends on tightly regulated trafficking and activation of ion channels. For the cystic fibrosis transmembrane conductance regulator (CFTR), dysregulation caused by tobacco smoke or chronic inflammation contributes to diseases such as chronic obstructive pulmonary disease (COPD). We previously showed that phosphorylation of CFTR at tyrosine 512 (Y512) by spleen tyrosine kinase promotes its internalization via the MAPK/SHC-1 pathway in CFBE airway cells. Here, we investigated whether this mechanism is conserved in other epithelial models and whether inhibition of SHC-1 increased CFTR abundance at the PM. CFTR surface levels were assessed in CFBE, 16HBE, and Caco-2 cells using biotinylation and immunoblotting after treatment with MEK inhibitor selumetinib, SHC-1 inhibitor idebenone (IDE), or its novel inhibitor 110#3. MAPK activity was evaluated by ERK phosphorylation. We found that MAPK/SHC-1-dependent CFTR internalization was conserved in 16HBE and Caco-2 cells. In CFBE cells, treatment with IDE or 110#3 increased PM CFTR levels, but also unrelated PM proteins (GLUT1 and E-cadherin). No significant effects were observed in 16HBE or Caco-2 cells. These findings suggest CFBE cells may not fully recapitulate endogenous CFTR trafficking and raise the possibility that selective SHC-1/pY512-CFTR inhibitors may modulate CFTR trafficking in COPD and other CFTR-related diseases.
- Rac1 signalling modulates a STAT5/BCL-6 transcriptional switch on cell-cycle-associated target gene promotersPublication . Barros, Patricia; Lam, Eric; Jordan, Peter; Matos, PauloGene expression depends on binding of transcriptional regulators to gene promoters, a process controlled by signalling pathways. The transcriptional repressor BCL-6downregulates genes involved in cell cycle progression and becomes inactivated following phosphorylation by the Rac1 GTPase activated protein kinase PAK1.Interestingly, the DNA motifs recognized by BCL-6 and STAT5 are similar. Because STAT5 stimulation in epithelial cells can also be triggered by Rac1 signalling, weasked whether both factors have opposing roles in transcriptional regulation and whether Rac1 signalling may coordinate a transcription factor switch. We usedchromatin immunoprecipitation to show that active Rac1 promotes release of the repressor BCL-6 while increasing binding of STAT5A to a BCL-6-regulated reportergene. We further show in colorectal cell lines that the endogenous activation status of the Rac1/PAK1 pathway correlated with the phosphorylation status of BCL-6and STAT5A. Three cellular genes (cyclin D2, p15INK4B, SUMO1) were identified to be inversely regulated by BCL-6 and STAT5A and responded to Rac1 signalling withincreased expression and corresponding changes in promoter occupancy. Together, our data show that Rac1 signalling controls a group of target genes that arerepressed by BCL-6 and activated by STAT5A, providing novel insights into the modulation of gene transcription by GTPase signalling.
- Stimulation of RAC1/PAK1 signalling upregulates DNA damage repair genes via STAT5 stimulation of BCL6 repressed lociPublication . Barros, Patricia; Amaral, Andreia; Abrantes, Leonor; Oliveira, Tiago; Louro, Henriqueta; Silva, Maria joão; Jordan, Peter; Gama-Carvalho, Margarida; Matos, PauloColorectal cancer is one of the most prevalent types of cancer worldwide. The GTPase RAC1 and its effector PAK1 have been found overexpressed or hyperactivated in colorectal cancers, particularly those with more aggressive and invasive features, leading to unfavourable clinical prognosis, often resulting from chemoresistance.
- Upregulation of RAC1/PAK1 signalling promotes DNA damage repair in colorectal cancer cellsPublication . Barros, Patricia; Amaral, Andreia; Abrantes, Leonor; Oliveira, Tiago; Louro, Henriqueta; Silva, Maria Joâo; Jordan, Peter; Gama Carvalho, Margarida; Matos, PauloIntroduction: Colorectal cancer is one of the most prevalent types of cancer worldwide. The GTPase RAC1 and its effector PAK1 have been found overexpressed or hyperactivated in this type of cancers, particularly those with more aggressive and invasive features, which is frequently correlated with resistance to chemotherapeutics and unfavourable clinical prognosis. Previously, we described a new signalling pathway in which activation of RAC1/PAK1 signalling promotes a transcriptional switch between the BCL6 repressor and the STAT5 transcriptional activator at a restricted subset of gene promoters.