Person: Porras Gallo, María Almudena
Loading...
First Name
María Almudena
Last Name
Porras Gallo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Farmacia
Department
Bioquímica y Biología Molecular
Area
Bioquímica y Biología Molecular
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item C3G, through its GEF activity, induces megakaryocytic differentiation and proplatelet formation(Cell communication and signaling, 2018) Ortiz Rivero, Sara; José María de Pereda; Anguita Mandly, Eduardo Luis; Porras Gallo, María Almudena; Guerrero, CarmenBackground: Megakaryopoiesis allows platelet formation, which is necessary for coagulation, also playing an important role in different pathologies. However, this process remains to be fully characterized. C3G, an activator of Rap1 GTPases, is involved in platelet activation and regulates several differentiation processes. Methods: We evaluated C3G function in megakaryopoiesis using transgenic mouse models where C3G and C3GΔCat (mutant lacking the GEF domain) transgenes are expressed exclusively in megakaryocytes and platelets. In addition, we used different clones of K562, HEL and DAMI cell lines with overexpression or silencing of C3G or GATA-1. Results: We found that C3G participates in the differentiation of immature hematopoietic cells to megakaryocytes. Accordingly, bone marrow cells from transgenic C3G, but not those from transgenic C3GΔCat mice, showed increased expression of the differentiation markers CD41 and CD61, upon thrombopoietin treatment. Furthermore, C3G overexpression increased the number of CD41+ megakaryocytes with high DNA content. These results are supported by data obtained in the different models of megakaryocytic cell lines. In addition, it was uncovered GATA-1 as a positive regulator of C3G expression. Moreover, C3G transgenic megakaryocytes from fresh bone marrow explants showed increased migration from the osteoblastic to the vascular niche and an enhanced ability to form proplatelets. Although the transgenic expression of C3G in platelets did not alter basal platelet counts, it did increase slightly those induced by TPO injection in vivo. Moreover, platelet C3G induced adipogenesis in the bone marrow under pathological conditions. Conclusions: All these data indicate that C3G plays a significant role in different steps of megakaryopoiesis, acting through a mechanism dependent on its GEF activity.Item Negative regulation of Akt activity by p38α MAP kinase in cardiomyocytes involves membrane localization of PP2A through interaction with caveolin-1(Cellular Signalling, 2007) Zuluaga, Susana; Álvarez-Barrientos, Alberto; Gutiérrez Uzquiza, Álvaro; Benito De Las Heras, Manuel R.; Nebreda, Angel R.; Porras, Almudena; Porras Gallo, María AlmudenaCardiomyocyte-derived cell lines deficient in p38α are more resistant to apoptosis owing to lower expression of the pro-apoptotic proteins Bax and Fas and upregulation of the ERK survival pathway. Here, we show that increased Akt activity also contributes to the enhanced survival of p38α-deficient cardiomyocytes. We found that the serine/threonine phosphatase PP2A can be targeted to caveolae through interaction with caveolin-1 in a p38α-dependent manner. In agreement with this, PP2A activity associated with caveolin-1 was higher in wild type than in p38α-deficient cells. Akt was also present in caveolae and incubation of wild-type cells with the PP2A inhibitor okadaic acid increases the levels of Akt activity. Thus, p38α-induced re-localization of PP2A to caveolae can lead to dephosphorylation and inhibition of Akt, which in turn would contribute to the decreased survival observed in wild type cells. However, cell detachment impairs the formation of the PP2A/caveolin-1 complex and, as a consequence, phospho-Akt levels and survival are no longer regulated by p38α in detached wild type cardiomyocytes. Our results suggest that p38α can negatively modulate Akt activity, independently of PI3K, by regulating the interaction between caveolin-1 and PP2A through a mechanism dependent on cell attachment.Item New and Old Key Players in Liver Cancer(International Journal of Molecular Sciences, 2023) Cuesta Martínez, Ángel; Palao, Nerea; Bragado Domingo, Paloma; Gutiérrez Uzquiza, Álvaro; Herrera González, Blanca María; Sánchez Muñoz, Aranzazu; Porras Gallo, María Almudena; Arechederra, Maria; Tarantino, Giovanni; Berasain, CarmenLiver cancer represents a major health problem worldwide with growing incidence and high mortality, hepatocellular carcinoma (HCC) being the most frequent. Hepatocytes are likely the cellular origin of most HCCs through the accumulation of genetic alterations, although hepatic progenitor cells (HPCs) might also be candidates in specific cases, as discussed here. HCC usually develops in a context of chronic inflammation, fibrosis, and cirrhosis, although the role of fibrosis is controversial. The interplay between hepatocytes, immune cells and hepatic stellate cells is a key issue. This review summarizes critical aspects of the liver tumor microenvironment paying special attention to platelets as new key players, which exert both pro- and anti-tumor effects, determined by specific contexts and a tight regulation of platelet signaling. Additionally, the relevance of specific signaling pathways, mainly HGF/MET, EGFR and TGF-β is discussed. HGF and TGF-β are produced by different liver cells and platelets and regulate not only tumor cell fate but also HPCs, inflammation and fibrosis, these being key players in these processes. The role of C3G/RAPGEF1, required for the proper function of HGF/MET signaling in HCC and HPCs, is highlighted, due to its ability to promote HCC growth and, regulate HPC fate and platelet-mediated actions on liver cancer.Item p38alpha MAPK can positively or negatively regulate Rac-1 activity depending on the presence of serum(FEBS Letters, 2007) Zuluaga, Susana; Gutiérrez Uzquiza, Álvaro; Bragado, Paloma; Alvarez-Barrientos, Alberto; Benito De Las Heras, Manuel R.; Nebreda, Angel R; Porras Gallo, María AlmudenaThe small GTP-ase Rac-1 can trigger p38 MAPK activation and, in turn, p38alpha can regulate signalling pathways that potentially impinge on Rac-1 activity. We have investigated the cross-talk between p38alpha and Rac-1 and found that p38alpha regulates the association between Rac-1 and caveolin-1 in serum-deprived cardiomyocytes. This interaction depends on cell attachment and correlates with higher levels of active Rac-1. Actin organization might regulate the formation of Rac-1-caveolin-1 complexes. In contrast, the Rac-1-caveolin-1 interaction is almost undetectable in the presence of serum, where Rac-1 activity is negatively regulated by p38alpha. Our results indicate that p38alpha can differentially contribute to Rac-1 activation depending on the presence of serum.Item C3G down-regulates p38 MAPK activity in response to stress by Rap-1 independent mechanisms: Involvement in cell death(Cellular Signalling, 2010) Gutiérrez Uzquiza, Álvaro; Arechederra, María; Molina, Isabel; Baños, Rocío; Maia, Vera; Benito De Las Heras, Manuel R.; Guerrero, Carmen; Porras Gallo, María AlmudenaWe present here evidences supporting a negative regulation of p38α MAPK activity by C3G in MEFs triggered by stress, which can mediate cell death or survival depending on the stimuli. Upon serum deprivation, C3G induces survival through inhibition of p38α activation, which mediates apoptosis. In contrast, in response to H2O2, C3G behaves as a pro-apoptotic molecule, as its knock-down or knock-out enhances survival through up-regulation of p38α activation, which plays an anti-apoptotic role under these conditions. Moreover, the C3G target, Rap-1, plays an opposite role, also through regulation of p38α MAPK activity. Our data also suggest that changes in the protein levels of some members of the Bcl-2 family could account for the regulation of cell death by C3G and/or Rap-1 through p38α MAPK. Bim/Bcl-xL ratio appears to be important in the regulation of cell survival, both upon serum deprivation and in response to H2O2. In addition, the increase in BNIP-3 levels induced by C3G knock-down in wt cells treated with H2O2 might play a role preventing cell death. Therefore, we can conclude that C3G is a negative regulator of p38α MAPK in MEFs, while Rap-1 is a positive regulator, but both, through the regulation of p38α activity, can promote cell survival or cell death depending on the stimuli.Item p38α Mediates Cell Survival in Response to Oxidative Stress via Induction of Antioxidant Genes(Journal of Biological Chemistry, 2012) Gutiérrez Uzquiza, Álvaro; Arechederra, María; Bragado Domingo, Paloma; Aguirre-Ghiso, Julio A.; Porras Gallo, María AlmudenaWe reveal a novel pro-survival role for mammalian p38α in response to H(2)O(2), which involves an up-regulation of antioxidant defenses. The presence of p38α increases basal and H(2)O(2)-induced expression of the antioxidant enzymes: superoxide-dismutase 1 (SOD-1), SOD-2, and catalase through different mechanisms, which protects from reactive oxygen species (ROS) accumulation and prevents cell death. p38α was found to regulate (i) H(2)O(2)-induced SOD-2 expression through a direct regulation of transcription mediated by activating transcription factor 2 (ATF-2) and (ii) H(2)O(2)-induced catalase expression through regulation of protein stability and mRNA expression and/or stabilization. As a consequence, SOD and catalase activities are higher in WT MEFs. We also found that this p38α-dependent antioxidant response allows WT cells to maintain an efficient activation of the mTOR/p70S6K pathway. Accordingly, the loss of p38α leads to ROS accumulation in response to H(2)O(2), which causes cell death and inactivation of mTOR/p70S6K signaling. This can be rescued by either p38α re-expression or treatment with the antioxidants, N-acetyl cysteine, or exogenously added catalase. Therefore, our results reveal a novel homeostatic role for p38α in response to oxidative stress, where ROS removal is favored by antioxidant enzymes up-regulation, allowing cell survival and mTOR/p70S6K activation.Item CRISPR/Cas9 screenings unearth protein arginine methyltransferase 7 as a novel essential gene in prostate cancer metastasis(Cancer Letters, 2024) Rodrigo Faus, María; Vincelle-Nieto, África; Vidal, Natalia; Puente, Javier; Saiz-Pardo Sanz, Melchor; López-García, Alejandra; Mendiburu-Eliçabe, Marina; Palao, Nerea; Baquero, Cristina; Linzoain-Agos, Paula; Cuesta Martínez, Ángel; Qu, Hui Qi; Hakonarson, Hakon; Musteanu, Mónica Andrea; Reyes Palomares, Armando Adolfo; Porras Gallo, María Almudena; Bragado Domingo, Paloma; Gutiérrez Uzquiza, ÁlvaroDue to the limited effectiveness of current treatments, the survival rate of patients with metastatic castration-resistant prostate cancer (mCRPC) is significantly reduced. Consequently, it is imperative to identify novel therapeutic targets for managing these patients. Since the invasive ability of cells is crucial for establishing and maintaining metastasis, the aim of this study was to identify the essential regulators of invasive abilities of mCRPC cells by conducting two independent high-throughput CRISPR/Cas9 screenings. Furthermore, some of the top hits were validated using siRNA technology, with protein arginine methyltransferase 7 (PRMT7) emerging as the most promising candidate. We demonstrated that its inhibition or depletion via genetic or pharmacological approaches significantly reduces invasive, migratory and proliferative abilities of mCRPC cells in vitro. Moreover, we confirmed that PRMT7 ablation reduces cell dissemination in chicken chorioallantoic membrane and mouse xenograft assays. Molecularly, PRMT7 reprograms the expression of several adhesion molecules by methylating various transcription factors, such as FoxK1, resulting in the loss of adhesion from the primary tumor and increased motility of mCRPC cells. Furthermore, PRMT7 higher expression correlates with tumor aggressivity and poor overall survival in prostate cancer patients. Thus, this study demonstrates that PRMT7 is a potential therapeutic target and potential biomarker for mPCa.