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- New fluorescent probes based on gallium(III) corrole complexes for the recognition of hydrogen sulfide: a journey from solution to intracellular sitePublication . Santos, Carla I.M.; Santiago, Ana M.; Araújo, Ana R.L.; Pinto, Sandra; Agostinho, Rafaela; Simão, Sónia; Azevedo, Tomás Pais de; Antunes, Catarina; Faustino, M. Amparo F.; Araujo, Ines; Neves, M. Graça P.M.S.; Martinho, José M.G.; Maçôas, Ermelinda M.S.In this work, three fluorescent probes for detection of hydrogen sulfide (H2S) where prepared based on gallium (III) corrole complexes bearing nitro groups at beta-pyrrolic positions. Two of the compounds selected, the 3-nitro5,10,15- tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-NO2) and the 3,17-dinitro-5,10,15-tris (pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-2NO2) present one and two nitro groups directly linked to the beta-pyrrolic position. The third compound, the (E)-3-(2-nitroprop-1-en-1-yl)-5,10,15-tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-EtNO2), has a carbon-carbon double bond spacer between the corrole unit and the nitro group. All these derivatives were obtained from 5,10,15-tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa). The precursor CGa and the derivative CGa-EtNO2 behaved as turn-OFF probes, while compound CGa-NO2 responded as a turn-ON probe in the presence of H2S in the pH range of 5-9. Mechanistic studies show that the interaction of H2S with the probes involves its coordination with gallium(III) and in some cases the reduction of the nitro group to a new aminated corrole. While the formation of the coordination complex with H2S is almost immediate, the kinetics of the reduction is slow. Interestingly, for CGaNO2 the two processes can be explored in a ratiometric sensing of H2S in a non-aqueous solution showing a good linearity over an extended concentration range (5-200 mu M). The response of the corroles to H2S in intracellular medium was studied in 2D cultured cells (HeLa).
- Regulation of Ras signaling by S-NitrosylationPublication . S, Simão; Agostinho, Rafaela; Martínez-Ruiz, Antonio; Araújo, Inês MariaRas are a family of small GTPases that function as signal transduction mediators and are involved in cell proliferation, migration, differentiation and survival. The significance of Ras is further evidenced by the fact that Ras genes are among the most mutated oncogenes in different types of cancers. After translation, Ras proteins can be targets of post-translational modifications (PTM), which can alter the intracellular dynamics of the protein. In this review, we will focus on how S-nitrosylation of Ras affects the way these proteins interact with membranes, its cellular localization, and its activity. S-Nitrosylation occurs when a nitrosyl moiety of nitric oxide (NO) is covalently attached to a thiol group of a cysteine residue in a target protein. In Ras, the conserved Cys118 is the most surface-exposed Cys and the preferable residue for NO action, leading to the initiation of transduction events. Ras transduces the mitogen-activated protein kinases (MAPK), the phosphoinositide-3 kinase (PI3K) and the RalGEF cellular pathways. S-Nitrosylation of elements of the RalGEF cascade remains to be identified. On the contrary, it is well established that several components of the MAPK and PI3K pathways, as well as different proteins associated with these cascades, can be modified by S-nitrosylation. Overall, this review presents a better understanding of Ras S-nitrosylation, increasing the knowledge on the dynamics of these proteins in the presence of NO and the underlying implications in cellular signaling.
- Unraveling the potential of gasotransmitters as neurogenic and neuroprotective molecules: focus on Alzheimer's and Parkinson's diseases.Publication . Simao, Sonia; Filipa Santos, Daniela; Teixeira, Mariana; Ribeiro Agostinho, Rafaela; Rodrigues, Joana; Vitorino, Marta; Pombinho de Araújo, Inês MariaAlzheimer's disease and Parkinson's disease are the two most prevalent neurodegenerative disorders worldwide, both characterized by progressive neuronal loss. Despite distinct pathophysiological features, they share cellular dysfunctions such as abnormal protein aggregation, oxidative stress, and neuroinflammation, research into which might be beneficial for developing novel therapeutic strategies that could tackle both conditions. This review highlights the emerging role of the gasotransmitters nitric oxide, carbon monoxide and hydrogen sulfide as modulators of adult neurogenesis and neuroprotection in Alzheimer's disease and Parkinson's disease. We have gathered recent evidence demonstrating that these endogenous gases exert anti-inflammatory, antioxidant, and anti-apoptotic effects, and, critically, promote neurogenesis - suggesting a dual neuroprotective and neuroregenerative therapeutic potential. The unique physicochemical features of these gasotransmitters, including their ability to cross the blood-brain barrier and diffuse rapidly throughout the neural tissue, further support their suitability as candidates for innovative neuroregenerative treatments. While clinical translation remains challenging, harnessing the neurogenic and neuroprotective actions of these gasotransmitters may offer transformative avenues for addressing the increasing burden of Alzheimer's disease and Parkinson's disease.