LSRE-LCM - Artigos em Revistas Nacionais e de Circulação Internacional
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Percorrer LSRE-LCM - Artigos em Revistas Nacionais e de Circulação Internacional por Domínios Científicos e Tecnológicos (FOS) "Ciências Médicas::Outras Ciências Médicas"
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- Are There Lipid Membrane-Domain Subtypes in Neurons with Different Roles in Calcium Signaling?Publication . Samhan-Arias, Alejandro K.; Poejo, Joana; Marques-da-Silva, Dorinda; Martínez-Costa, Oscar H.; Gutierrez-Merino, CarlosLipid membrane nanodomains or lipid rafts are 10–200 nm diameter size cholesterol- and sphingolipid-enriched domains of the plasma membrane, gathering many proteins with different roles. Isolation and characterization of plasma membrane proteins by differential centrifugation and proteomic studies have revealed a remarkable diversity of proteins in these domains. The limited size of the lipid membrane nanodomain challenges the simple possibility that all of them can coexist within the same lipid membrane domain. As caveolin-1, flotillin isoforms and gangliosides are currently used as neuronal lipid membrane nanodomain markers, we first analyzed the structural features of these components forming nanodomains at the plasma membrane since they are relevant for building supramolecular complexes constituted by these molecular signatures. Among the proteins associated with neuronal lipid membrane nanodomains, there are a large number of proteins that play major roles in calcium signaling, such as ionotropic and metabotropic receptors for neurotransmitters, calcium channels, and calcium pumps. This review highlights a large variation between the calcium signaling proteins that have been reported to be associated with isolated caveolin-1 and flotillin-lipid membrane nanodomains. Since these calcium signaling proteins are scattered in different locations of the neuronal plasma membrane, i.e., in presynapses, postsynapses, axonal or dendritic trees, or in the neuronal soma, our analysis suggests that different lipid membrane-domain subtypes should exist in neurons. Furthermore, we conclude that classification of lipid membrane domains by their content in calcium signaling proteins sheds light on the roles of these domains for neuronal activities that are dependent upon the intracellular calcium concentration. Some examples described in this review include the synaptic and metabolic activity, secretion of neurotransmitters and neuromodulators, neuronal excitability (long-term potentiation and long-term depression), axonal and dendritic growth but also neuronal cell survival and death.
- Autosomal recessive hypotrichosis with loose anagen hairs associated with TKFC mutations*Publication . Onoufriadis, A.; Cabezas, A.; Ng, J. C. F.; Canales, J.; Costas, M. J.; Ribeiro, J. M.; Rodrigues, J. R.; McAleer, M. A.; Castelo‐Soccio, L.; Simpson, M. A.; Fraternali, F.; Irvine, A. D.; Cameselle, J. C.; McGrath, J. A.Background: Loose anagen hair is a rare form of impaired hair anchorage in which anagen hairs that lack inner and outer root sheaths can be gently and painlessly plucked from the scalp. This condition usually occurs in children and is often self-limiting. A genetic basis for the disorder has been suggested but not proven. A better understanding the aetiology of loose anagen hair may improve prevention and treatment strategies. Objectives: To identify a possible genetic basis of loose anagen hair using next-generation DNA sequencing and functional analysis of variants identified. Methods: In this case study, whole-exome sequencing analysis of a pedigree with one affected individual with features of loose anagen hair was performed. Results: The patient was found to be compound heterozygous for two single-nucleotide substitutions in TKFC resulting in the following missense mutations: c.574G> C (p.Gly192Arg) and c.682C> T (p.Arg228Trp). Structural analysis of human TKFC showed that both mutations are located near the active site cavity. Kinetic assays of recombinant proteins bearing either of these amino acid substitutions showed almost no dihydroxyacetone kinase or D-glyceraldehyde kinase activity, and FMN cyclase activity reduced to just 10% of wildtype catalytic activity. Conclusions: TKFC missense mutations may predispose to the development of loose anagen hairs. Identification of this new biochemical pathobiology expands the metabolic and genetic basis of hypotrichosis.