Skeletal muscle adapts differently to specific modes of exercise, where resistance training results in muscle growth and endurance training induces mitochondrial biogenesis. These are results of molecular events that occur after each exercise session, increasing the expression of specific genes and the rate of both synthesis and breakdown of protein. The rate of protein synthesis is controlled by the mTORC1 signaling pathway, which is potently stimulated by resistance exercise and amino acid, and their combined effect is needed for muscle growth. The essential amino acids (EAA) are responsible for the stimulation of protein synthesis and here leucine has been attributed specific attention, but its particular role among the EAA, and the involvement of the other branched-chain amino acids (BCAA) is unclear. Endurance exercise activates the protein AMPK which, in animal models, has been shown to inhibit mTORC1 signaling and protein synthesis.  Suggesting that concurrent endurance and resistance exercise could restrain muscle growth, but it is unknown if this mechanism is relevant in exercising human muscle. Little is known about the regulation of protein breakdown and although much attention has been given the proteins MuRF-1 and MAFbx which target proteins for degradation, their role requires further investigation. The aim of thesis was to address the mentioned uncertainties by examining how different modes of exercise and amino acids affect mTORC1 signaling, protein synthesis and markers of protein breakdown in human muscle. In study I, the influence of high intensity endurance exercise on subsequent resistance exercised induced mTORC1 signaling was examined. Despite robust activation of AMPK by the endurance exercise there was no inhibition of mTORC1 signaling or protein synthesis during recovery from resistance exercise. Study II utilized a similar set up, but with the difference that resistance exercise was performed with the triceps. The cycling exercise reduced the resistance exercise stimulated mTORC1 signaling immediately after the exercise, but during the recovery period mTORC1 signaling and protein synthesis was similar between trials. Concurrent exercise induced the mRNA expression of MuRF-1 and that of PGC-1α, the master regulator of mitochondrial biogenesis, in both studies, despite that the exercise modes in study II were separated between legs and arms. In study III, the effect of an EAA supplement with or without leucine, in the stimulation of mTORC1 signaling in connection with resistance exercise was examined. Intake of EAA robustly stimulated mTORC1 signaling after exercise, but this was only minor when leucine was excluded from the supplement. In study IV, subjects were supplied with leucine, BCAA, EAA or placebo in a randomized fashion during four sessions of resistance exercise. Leucine alone stimulated mTORC1 signaling after the exercise, but both the amplitude and extent of stimulation was substantially greater with EAA, an effect that was largely mediated by the BCAA as a group. In conclusion, endurance exercise prior to resistance exercise using the leg or arm muscles does not affect mTORC1 signaling or protein synthesis during the three hour recovery period from exercise, supporting compatibility between resistance- and endurance exercise induced signaling. Concurrent exercise increases the expression of the proteolytic marker MuRF-1 compared to resistance exercise only, which could indicate both and increased demand of cellular adaptive remodeling or a more direct detrimental proteolytic effect. Leucine is crucial among the EAA in the stimulation of mTORC1 signaling after exercise, its effect is however potentiated by intake of the remaining EAA. As a supplement a mixture of EAA must be regarded preferable, although the effect is largely mediated by the BCAA as a group.

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O transtorno do espectro do autismo (TEA) constitui um grupo heterogêneo e altamente prevalente de doenças do neurodesenvolvimento. Análises genômicas recentes têm revelado um grande número de variantes genéticas potencialmente deletérias nos pacientes com TEA, a maioria rara ou privada. Um enorme desafio atual é determinar quais dentre essas variantes são as que de fato estão envolvidas na etiologia do transtorno nos pacientes, e quantas variantes patogênicas são necessárias para a penetrância completa do TEA em cada paciente. Recentemente, por meio do sequenciamento completo do exoma de um subgrupo de pacientes com TEA não-sindrômico - nos quais observamos hiperfuncionamento da via de sinalização intracelular mTORC1 - identificamos que um dos pacientes (referido como F2688) é heterozigoto composto para variantes de substituição de aminoácidos raras e potencialmente deletérias no gene ELN. Este gene codifica Relina, uma grande glicoproteína de matriz extracelular que, por meio da ativação da proteína Dab1 e de diferentes vias de sinalização intracelular, controla a migração e o posicionamento dos neurônios, a arborização de neuritos, e o funcionamento das sinapses em várias regiões do encéfalo, tanto no desenvolvimento embrionário como na vida adulta. Estudos anteriores já haviam descrito variantes em heterozigose potencialmente de perda de função no gene RELN em pacientes com TEA; contudo, nenhum desses estudos investigou disfunção da sinalização Relina-Dab1 nos pacientes e, portanto, os efeitos moleculares e celulares de tais variantes sobre células neurais humanas ainda são poucos explorados. Neste trabalho, utilizando células neuroprogenitoras (NPCs) derivadas de células-tronco pluripotentes induzidas do paciente F2688, de outros pacientes com TEA sem mutação em RELN (n=5) e de indivíduos controles (n=5), nós descrevemos que as NPCs do paciente F2688 apresentam: i) disfunção da via de sinalização Relina-Dab1; ii) hiperfuncionamento da via de sinalização mTORC1; iii) crosstalk anormal entre as vias de sinalização Relina-Dab1 e mTORC1, o qual é atenuado com o uso da rapamicina, um inibidor específico de mTORC1. Portanto, nossos resultados sugerem, pela primeira vez, uma relação anormal entre as vias de sinalização Relina-Dab1 e mTORC1 em TEA não-sindrômico / Autism Spectrum Disorder (ASD) is a heterogeneous and highly prevalent group of neurodevelopmental disorders. Whole-genome-based approaches have generated catalogues of thousands of rare and potentially deleterious genetic variants in ASD patients. However, the challenge now is to identify genuine disease-causing/risk variants among the multitude of variants discovered in each exome/genome and how many variants are required to cause the disease. Recently, we performed whole-exome sequencing in a subgroup of ASD patients - in whom we found mTORC1 signaling hyperfunction - and identified rare and potentially deleterious compound heterozygous variants in the RELN gene in one patient (called as F2688). The RELN gene encodes Reelin, a large secreted glycoprotein that controls neuronal migration, layer formation, neurite outgrowth, and plasticity of synapses in both the developing and the adult brain. Evidence from previous studies suggests that certain potential loss-of-function variants in RELN gene can contribute to ASD susceptibility; however, few studies today have directly demonstrated impairment of the Reelin signal transduction cascade in ASD patients and therefore, the molecular and cellular effects of these variants in human neuronal cells are still poorly explored. Here, by using induced pluripotent stem cells derived neuronal progenitor cells from F2688 patient, from other ASD patients who do not carry RELN disrupting variants (n=5) and from control individuals (n=5), we have demonstrated that F2688-derived NPCs show: i) impaired Reelin-Dab1 signaling; ii) overactive mTORC1 signaling; iii) and abnormal crosstalk between mTORC1 and Reelin-Dab1 signaling pathways, which it attenuated by rapamycin (a specific mTORC1 inhibitor). Taken together, our results point to an abnormal interplay between mTORC1 and Reelin-Dab1 networks in nonsyndromic ASD