Selective Interaction of Syntaxin 1A with KCNQ2: Possible Implications for Specific Modulation of Presynaptic Activity

KCNQ2/KCNQ3 channels are the molecular correlates of the neuronal M-channels, which play a major role in the control of neuronal excitability. Notably, they differ from homomeric KCNQ2 channels in their distribution pattern within neurons, with unique expression of KCNQ2 in axons and nerve terminals. Here, combined reciprocal coimmunoprecipitation and two-electrode voltage clamp analyses in Xenopus oocytes revealed a strong association of syntaxin 1A, a major component of the exocytotic SNARE complex, with KCNQ2 homomeric channels resulting in a ∼2-fold reduction in macroscopic conductance and ∼2-fold slower activation kinetics. Remarkably, the interaction of KCNQ2/Q3 heteromeric channels with syntaxin 1A was significantly weaker and KCNQ3 homomeric channels were practically resistant to syntaxin 1A. Analysis of different KCNQ2 and KCNQ3 chimeras and deletion mutants combined with in-vitro binding analysis pinpointed a crucial C-terminal syntaxin 1A-association domain in KCNQ2. Pull-down and coimmunoprecipitation analyses in hippocampal and cortical synaptosomes demonstrated a physical interaction of brain KCNQ2 with syntaxin 1A, and confocal immunofluorescence microscopy showed high colocalization of KCNQ2 and syntaxin 1A at presynaptic varicosities. The selective interaction of syntaxin 1A with KCNQ2, combined with a numerical simulation of syntaxin 1A's impact in a firing-neuron model, suggest that syntaxin 1A's interaction is targeted at regulating KCNQ2 channels to fine-tune presynaptic transmitter release, without interfering with the function of KCNQ2/3 channels in neuronal firing frequency adaptation

Nuclear poly(ADP-ribose) activity is a therapeutic target in amyotrophic lateral sclerosis

Abstract Amyotrophic lateral sclerosis (ALS) is a devastating and fatal motor neuron disease. Diagnosis typically occurs in the fifth decade of life and the disease progresses rapidly leading to death within ~ 2–5 years of symptomatic onset. There is no cure, and the few available treatments offer only a modest extension in patient survival. A protein central to ALS is the nuclear RNA/DNA-binding protein, TDP-43. In > 95% of ALS patients, TDP-43 is cleared from the nucleus and forms phosphorylated protein aggregates in the cytoplasm of affected neurons and glia. We recently defined that poly(ADP-ribose) (PAR) activity regulates TDP-43-associated toxicity. PAR is a posttranslational modification that is attached to target proteins by PAR polymerases (PARPs). PARP-1 and PARP-2 are the major enzymes that are active in the nucleus. Here, we uncovered that the motor neurons of the ALS spinal cord were associated with elevated nuclear PAR, suggesting elevated PARP activity. Veliparib, a small-molecule inhibitor of nuclear PARP-1/2, mitigated the formation of cytoplasmic TDP-43 aggregates in mammalian cells. In primary spinal-cord cultures from rat, Veliparib also inhibited TDP-43-associated neuronal death. These studies uncover that PAR activity is misregulated in the ALS spinal cord, and a small-molecular inhibitor of PARP-1/2 activity may have therapeutic potential in the treatment of ALS and related disorders associated with abnormal TDP-43 homeostasis

Waste sourced bio-based substances for solar-driven wastewater remediation: Photodegradation of emerging pollutants

The effect of soluble bio-based organic substances (SBO) isolated from urban wastes on photochemical wastewater treatments was investigated using a mixture of six emerging pollutants (EPs), namely acetaminophen, caffeine, acetamiprid, clofibric acid, carbamazepine and amoxicillin. Solar simulated experiments showed that although SBO were able to enhance the indirect photolysis of the EPs, they could not compensate for the light screening effect produced by these colored materials. In contrast, SBO were able to enhance photo-Fenton at slightly acidic conditions (pH = 5.2), most probably increasing iron availability. In the later case, the order of reactivity (amoxicillinPcarbamazepine Pclofibric acid > caffeine > acetaminophen > acetamiprid) was similar to that of the rate constants determined for all six EPs with OH. Finally, experiments performed at pilot plant scale with real sunlight at pH = 5.2 and SBO showed that 5 of the EPs were removed in only 25 min and only acetamiprid was more resistant to the process. The overall results show not only how we can use waste to clean out wastes, but also contribute to the studies which show how wastes can become a source of revenue through the industrial exploitation of their chemical value.The authors want to thank the financial support of the European Union (PIRSES-GA-2010-269128, EnvironBOS) and Spanish Ministerio de Economia y Competitividad (CTQ2012-38754-C03-02). L. Carlos wishes to acknowledge CONICET (Argentina) and D.O. Martire to CIC (Provincia de Buenos Aires, Argentina). Part of this work was carried also with the Italian Ministero delle Politiche Agricole funds within the Agrienergia project. The authors are grateful to the following private and/or public Italian institutions: (a) Acea Pinerolese Spa in Pinerolo (TO) for supplying the SBO sourcing biowastes; (b) Studio Chiono ed Associati in Rivarolo Canavese (TO) for making available pilot equipment and services for the production of SBO.Gomis Vicens, J.; Prevot, AB.; Montoneri, E.; Gonzalez, MC.; Amat Payá, AM.; Martire, DO.; Arques Sanz, A.... (2014). Waste sourced bio-based substances for solar-driven wastewater remediation: Photodegradation of emerging pollutants. Chemical Engineering Journal. 235:236-243. https://doi.org/10.1016/j.cej.2013.09.009S23624323