Search

Clinical exome sequencing has the potential to identify pathogenic variants unrelated to the purpose of the study (secondary findings, SFs). Data describing actual choices of SFs in participants in a clinical setting and factors influencing their decision are virtually non-existant in Europe. In this work, we report the acceptance rate of SFs, calculate their prevalence and study factors associated with the decision in a cohort of patients affected with a rare genetic disorder in a Spanish Hospital. Finally, we re-examine the presence of previously non reported family history in positive cases. We retrospectively reviewed informed consent choices and SF results from 824 unrelated probands affected with rare genetic disorders who underwent whole-genome or exome sequencing. Ninety percent of families (740/824) affected with rare disorders wished to be informed of SFs. Declining SFs was associated with a prenatal setting (30% vs. 8.7%, p = 0.025), consanguinity (19% vs. 8.7%, p = 0.013), male gender (10.6% vs. 1.5%, p = 0.00865) and the proband being a minor (10.6% vs. 1.5%, p = 0.014). Overall, 27 pathogenic or likely pathogenic variants were identified in 27 individuals, with an SF prevalence of 3.6%. Disclosure of SFs increased the percentage of positive family histories and resulted in early diagnosis or changes in the management of 10 individuals from five families. We show that the acceptance of SFs in Spain is high and the disclosure of SFs leads to a clinically meaningful change in the medical management of individuals.

Left ventricular noncompaction (LVNC) is a heterogeneous entity with uncertain prognosis. This study sought to develop and validate a prediction model of major adverse cardiovascular events (MACE) and to identify LVNC cases without events during long-term follow-up. This is a retrospective longitudinal multicenter cohort study of consecutive patients fulfilling LVNC criteria by echocardiography or cardiovascular magnetic resonance. MACE were defined as heart failure (HF), ventricular arrhythmias (VAs), systemic embolisms, or all-cause mortality. A total of 585 patients were included (45 ± 20 years of age, 57% male). LV ejection fraction (LVEF) was 48% ± 17%, and 18% presented late gadolinium enhancement (LGE). After a median follow-up of 5.1 years, MACE occurred in 223 (38%) patients: HF in 110 (19%), VAs in 87 (15%), systemic embolisms in 18 (3%), and 34 (6%) died. LVEF was the main variable independently associated with MACE (P < 0.05). LGE was associated with HF and VAs in patients with LVEF >35% (P < 0.05). A prediction model of MACE was developed using Cox regression, composed by age, sex, electrocardiography, cardiovascular risk factors, LVEF, and family aggregation. C-index was 0.72 (95% confidence interval: 0.67-0.75) in the derivation cohort and 0.72 (95% confidence interval: 0.71-0.73) in an external validation cohort. Patients with no electrocardiogram abnormalities, LVEF ≥50%, no LGE, and negative family screening presented no MACE at follow-up. LVNC is associated with an increased risk of heart failure and ventricular arrhythmias. LVEF is the variable most strongly associated with MACE; however, LGE confers additional risk in patients without severe systolic dysfunction. A risk prediction model is developed and validated to guide management. The project was partially funded by a grant from the Catalan Society of Cardiology (Barcelona, Spain). Hospital Universitario Virgen de la Arrixaca (Murcia, Spain) was supported by a grant from the Foundation Marató TV3 (218/C/2015) (Barcelona, Spain). Hospital Universitario y Politécnico La Fe (Valencia, Spain) was partially supported by Fondo Europeo de Desarrollo Regional (“Unión Europea, Una forma de hacer Europa”) (Madrid, Spain) and the Instituto de Salud Carlos III (La Fe Biobank PT17/0015/ 0043) (Madrid, Spain). Dr Guala was supported by funding from the Spanish Ministry of Science, Innovation and Universities (IJC2018-037349-I) (Madrid, Spain). Dr La Mura was supported by a research grant from the Cardiopath PhD program (Naples, Italy). Prof de la Pompa was supported by grants PID2019-104776RB-I00 and CB16/11/00399 (CIBER CV) from the Spanish Ministry of Science, Innovation and Universities. Dr Bayes-Genis was supported by grants from CIBER Cardiovascular (CB16/11/00403 and 16/11/00420) (Madrid, Spain) and AdvanceCat 2014-2020 (Barcelona, Spain); and has received advisory board and lecture fees from Novartis, Boehringer Ingelheim, Vifor, Roche Diagnostics, and Critical Diagnostics. Dr Pontone has received speaker honorarium and/or institutional research grants from GE Healthcare, Bracco, Boehringer Ingelheim, and HeartFlow. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Sí

Research has drawn attention to the stigma and high rates of victimization among people with intellectual disabilities (ID) and an overlap between bias and non-bias victimization. However, studies of bias events or hate crime involving persons with ID are scarce. Using a self-report measure, we analyze lifetime bias victimization in a sample of 260 adults diagnosed with ID (age M = 41.7, SD = 12.0; 59.2% men), of whom 92 experienced bias victimization (age M = 41.2, SD = 11.9; 54.3% men), and compare the number of different types of victimization and the poly-victimization status between bias and non-bias victims. We also examine the following features: the victim, offender(s), victim–offender relationship, and location. Results show that bias victims experience a higher number of different types of victimization than non-bias victims ( M = 7.74 and 4.96, respectively; p rb=.37, ξ=.42) and are four times more likely to be poly-victims than non-bias victims (odds ratio [ OR] = 4.37; 95% CI, p

BackgroundA proportion of de novo variants in patients affected by genetic disorders, particularly those with autosomal dominant (AD) inheritance, could be the consequence of somatic mosaicism in one of the progenitors. There is growing evidence that germline and somatic mosaicism are more common and play a greater role in genetic disorders than previously acknowledged. In Marfan syndrome (MFS), caused by pathogenic variants in the fibrillin-1 gene (FBN1) gene, approximately 25% of the disease-causing variants are reported as de novo. Only a few cases of parental mosaicism have been reported in MFS.MethodsEmploying an amplicon-based deep sequencing (ADS) method, we carried out a systematic analysis of 60 parents of 30 FBN1 positive, consecutive patients with MFS with an apparently de novo pathogenic variant.ResultsOut of the 60 parents studied (30 families), the majority (n=51, 85%) had a systemic score of 0, seven had a score of 1 and two a score of 2, all due to minor criteria common in the normal population. We detected two families with somatic mosaicism in one of the progenitors, with a rate of 6.6% (2/30) of apparently de novo cases.ConclusionsThe search for parental somatic mosaicism should be routinely implemented in de novo cases of MFS, to offer appropriate genetic and reproductive counselling as well as to reveal masked, isolated clinical signs of MFS in progenitors that may require specific follow-up.

Spinal muscular atrophy (SMA) is a severe neuromuscular disorder caused by biallelic loss or pathogenic variants in the

Cerebellofaciodental syndrome (MIM #616202) is an autosomal recessive condition characterized by intellectual disability, microcephaly, cerebellar hypoplasia, dysmorphic features, and short stature. To date, eight patients carrying biallelic BRF1 variants have been reported. Here, we describe two siblings with congenital microcephaly and corpus callosum hypoplasia, pre and postnatal growth retardation, congenital heart defect and severe global developmental delay. We also detected additional findings not previously reported in this syndrome, including bilateral sensorineural hearing impairment and inner ear malformation. Whole exome sequencing identified a novel homozygous missense variant (c.654G>C, p.[Trp218Cys]) in BRF1, predicted to affect the protein structure. Expression assessment showed extremely low BRF1 protein expression caused by the identified variant, supporting its causal involvement. The description of new patients with cerebellofaciodental syndrome is essential to better delineate the phenotypic and genotypic spectrum of the disease.

People with intellectual disabilities appear to be more vulnerable to victimization. However, few studies have assessed victimization in these groups and those that do exist are highly heterogeneous and tend to focus only on specific forms of violence. This study attempts to shed light on the phenomenon of victimization among adults with intellectual disabilities by assessing victimization and poly-victimization throughout their life course. The sample consisted of 260 adults (154 men and 106 women) with an intellectual disability diagnosis, recruited from the Catalan Federation for People with Intellectual Disabilities (DINCAT) in Spain. They ranged in age from 20 to 71 years ( M = 41.69, SD = 12.05). Victimization experiences were assessed by means of an adaptation of the retrospective version of the Juvenile Victimization Questionnaire (JVQ). The results showed that 96.9% of the participants had suffered some kind of victimization throughout their lives. With respect to the types of victimization, the most frequent were common victimization (87.7%), witnessing and indirect victimization (67.3%), victimization by caregivers (59.2%), sexual victimization (35%), and electronic victimization (23.5%). Women and early adults tended to experience higher rates of victimization. The poly-victimized group experienced 13 or more incidents of victimization throughout their lives. This study highlights the elevated rates of lifetime victimization among people with intellectual disabilities. It adds to previous evidence that special protection programs are required to address this issue and emphasizes the need for prevention and intervention measures in this particularly vulnerable group.

This study examines the prevalence and characteristics of sexual victimization experiences suffered by people with intellectual disabilities (ID). The sample consisted of 260 adults with an ID diagnosis (154 men and 106 women), ranging in age from 20 to 71 years (M = 41.69, SD = 12.05). The results showed that 35% of the sample had been sexually victimized at some point in their life. Being a woman, being declared legally incapable, and having comorbid mental health diagnoses were the most relevant characteristics of sexual victims with ID. Fondling was the most reported victimization, and rape showed the greatest gender differences, with a higher risk for women with ID of being raped compared to their male counterparts (odds ratio = 4.28, p < .05). The offender was generally a known male adult, and the percentage of incidents reported to the authorities was very low (7.4%). The psychological consequences of abuse were general distress, anxiety, and depressive symptomatology. Intervention and prevention programs targeting this population, as well as the training of professionals and caregivers, are essential to deal with sexual victimization and to protect and ensure the quality of life of people with ID.

Acute myocarditis is an inflammatory disease of the myocardium, and it can present as severe heart failure in children. Differential diagnosis with genetic cardiomyopathy can be difficult. The objective of this study is to identify patterns of clinical presentation and to assess invasive and non-invasive measures to differentiate patients with acute myocarditis from patients with dilated genetic cardiomyopathy. We performed a retrospective descriptive study of all paediatric patients (0–16 years old) that presented with new-onset heart failure with left ventricle ejection fraction

espanolLa explotacion sexual comercial infantil y adolescente (ESCIA) es un problema especialmente frecuente en ninos, ninas y adolescentes con medidas juridicas de proteccion. Esta forma de victimizacion sexual, que recoge otras multiples formas de violencia, no solo esta presente en paises en vias de desarrollo. En Espana, unicamente contamos con los datos obtenidos por la Comision de Expertos de Mallorca en 2020. Se presentan las respuestas de 67 adolescentes, entre 13 y 18 anos, en centros residenciales del sistema de proteccion, sobre sus conocimientos y experiencias respecto a la ESCIA. Los resultados indican que se trata de un problema conocido y ante el cual demandan mas educacion y proteccion. Aluden a motivos diversos para implicarse en el, pero todos ellos pueden situarse dentro de la piramide del sexo por supervivencia. El uso de las TIC aparece como un importante factor de riesgo a tener en cuenta en programas de prevencion. EnglishCommercial sexual exploitation of children (CSEC) is a problem that is highly prevalent in children and adolescents under legal protection. However, this form of sexual victimization, which includes multiple other forms of violence, is not only present in developing countries. In Spain we only have the data obtained by the Expert Commission from Mallorca in 2020. The responses of a sample of 67 adolescents between 13 and 18 years old from residential centers in Mallorca about their knowledge and experiences regarding CSEC are presented. The results indicate that CSEC is a known problem. These adolescents also demand more education and protection. They allude to various reasons for engaging in this type of behavior, although all of them can be placed in the pyramid of survival sex. The use of ICT appears as an important risk factor to take into account in prevention programs.

A proportion of de novo variants in patients affected by genetic disorders, particularly those with autosomal dominant (AD) inheritance, could be the consequence of somatic mosaicism in one of the progenitors. There is growing evidence that germline and somatic mosaicism are more common and play a greater role in genetic disorders than previously acknowledged. In Marfan syndrome (MFS), caused by pathogenic variants in the fibrillin-1 gene (Employing an amplicon-based deep sequencing (ADS) method, we carried out a systematic analysis of 60 parents of 30Out of the 60 parents studied (30 families), the majority (n=51, 85%) had a systemic score of 0, seven had a score of 1 and two a score of 2, all due to minor criteria common in the normal population. We detected two families with somatic mosaicism in one of the progenitors, with a rate of 6.6% (2/30) of apparently de novo cases.The search for parental somatic mosaicism should be routinely implemented in de novo cases of MFS, to offer appropriate genetic and reproductive counselling as well as to reveal masked, isolated clinical signs of MFS in progenitors that may require specific follow-up.

In the last years the total energy consumption of data centre industry has experienced a rapid increase due to the vast growth in internet usage. This phenomenon has aroused the interest for both, data centre industry and researchers in energy consumption and carbon footprint mitigation. Data centres operational expenses are also a key parameter for the productivity and competitiveness of the industry. In the present work, the implementation and optimization of thermal energy storage (TES) into a real data centre is presented. To the knowledge of the authors this is the first time that a methodology based on TraNsient System Simulation (TRNSYS), GenOpt and the application of Hooke and Jeeves optimization algorithm is used to study the implementation of TES, in particular water storage tanks, in data centres. A sensitivity analysis on the TES system cost is performed in function of the available literature information. The results show that the operating temperature of the chillers should be as lower as the system allows and therefore this open the possibility to study ice storage system. Regarding the economic analysis, the data centre electricity expenses can be reduced annually up to 3%. The uncertainty of the electricity price in the future is a major issue and it is also discussed.

Funding this work was funded by grants from the Spanish Ministry of economy and competiveness (FiS Pi16/00369 and Pi1302481 cofunded by FeDer, and 'Programa de excelencia María de Maeztu' MDM-2014-0370), and the generalitat de catalunya (2017Srg01974 and icrea-acadèmia program). Mc-r had a predoctoral fellowship of Ministry of education, culture and Sport (FPU16/06907) and DP-g had a predoctoral fellowship from the instituto de Salud carlos iii (Fi11/00656). Background The hallmark of the neurobehavioural phenotype of Williams-Beuren syndrome (WBS) is increased sociability and relatively preserved language skills, often described as opposite to autism spectrum disorders (ASD). However, the prevalence of ASD in WBS is 6-10 times higher than in the general population. We have investigated the genetic factors that could contribute to the ASD phenotype in individuals with WBS. Methods We studied four males and four females with WBS and a confirmed diagnosis of ASD by the Autism Diagnostic Interview-Revised. We performed a detailed molecular characterisation of the deletion and searched for genomic variants using exome sequencing. Results A de novo deletion of 1.55 Mb (6 cases) or 1.83 Mb (2 cases) at 7q11.23 was detected, being in 7/8 patients of paternal origin. No common breakpoint, deletion mechanism or size was found. Two cases were hemizygous for the rare T allele at rs12539160 in MLXIPL, previously associated with ASD. Inherited rare variants in ASD-related or functionally constrained genes and a de novo nonsense mutation in the UBR5 gene were identified in six cases, with higher burden in females compared with males (p=0.016). Conclusions The increased susceptibility to ASD in patients with WBS might be due to additive effects of the common WBS deletion, inherited and de novo rare sequence variants in ASD-related genes elsewhere in the genome, with higher burden of deleterious mutations required for females, and possible hypomorphic variants in the hemizygous allele or cis-acting mechanisms on imprinting.

Engelken, Johannes et al., Essential trace elements possess vital functions at molecular, cellular, and physiological levels in health and disease, and they are tightly regulated in the human body. In order to assess variability and potential adaptive evolution of trace element homeostasis, we quantified 18 trace elements in 150 liver samples, together with the expression levels of 90 genes and abundances of 40 proteins involved in their homeostasis. Additionally, we genotyped 169 single nucleotide polymorphism (SNPs) in the same sample set. We detected significant associations for 8 protein quantitative trait loci (pQTL), 10 expression quantitative trait loci (eQTLs), and 15 micronutrient quantitative trait loci (nutriQTL). Six of these exceeded the false discovery rate cutoff and were related to essential trace elements: 1) one pQTL for GPX2 (rs10133290); 2) two previously described eQTLs for HFE (rs12346) and SELO (rs4838862) expression; and 3) three nutriQTLs: The pathogenic C282Y mutation at HFE affecting iron (rs1800562), and two SNPs within several clustered metallothionein genes determining selenium concentration (rs1811322 and rs904773). Within the complete set of significant QTLs (which involved 30 SNPs and 20 gene regions), we identified 12 SNPs with extreme patterns of population differentiation (FST values in the top 5% percentile in at least one HapMap population pair) and significant evidence for selective sweeps involving QTLs at GPX1, SELENBP1, GPX3, SLC30A9, and SLC39A8. Overall, this detailed study of various molecular phenotypes illustrates the role of regulatory variants in explaining differences in trace element homeostasis among populations and in the human adaptive response to environmental pressures related to micronutrients., This work was supported by Ministerio de Ciencia e Innovación, Spain (grants BFU2008-01046 and SAF2011-29239) and by Direcció General de Recerca, Generalitat de Catalunya (2009SGR-1101 and 2014SGR-866). The CRG/UPF Proteomics Unit is part of the “Plataforma de Recursos Biomoleculares y Bioinformáticos (ProteoRed)” supported by grant PT13/0001 of the Instituto de Salud Carlos III (ISCIII). J.E. was supported by a Postdoctoral scholarship from the Volkswagenstiftung (Az: I/85 198).

Primary cultures of rainbow trout skeletal muscle cells were used to examine the role of insulin-like growth factor II (IGF-II) in fish muscle metabolism and growth, and to compare its main signal transduction pathways with those of IGF-I. IGF-II stimulated 2-deoxy-d-glucose (2-DG) uptake in trout myocytes at concentrations of between 5 and 100 nM, with similar maximal effects and temporal pattern to IGF-I (100 nM). The results of incubation with inhibitors (Wortmannin and CKB) indicated that IGF-II stimulates glucose uptake through the same mechanisms as IGF-I. In addition, IGF-II stimulated myoblast DNA synthesis (measured by thymidine incorporation) at relatively low concentrations (0.1-10 nM), with the maximum increase at 1 nM (167+/-17% with respect to control values). The cells were immunoreactive against ERK 1/2 MAPK and Akt/PKB, components of the two main signal transduction pathways for the IGF-I receptor. IGF-II stimulated the phosphorylation of the protein MAPK, especially at the proliferation stage (increases of up to 125.7+/-16.9% and 125.3+/-3.3% with respect to control in IGF-II- and IGF-I-treated cells, respectively). In contrast, the effects of both IGFs on the activation of the PI3K/Akt pathway were stronger in fully differentiated myocytes and in early-formed fibres (up to 359+/-18.5% in IGF-II-treated cells with respect to control). These results indicate that IGF-II has both mitogenic and metabolic effects in trout muscle cells, which are equivalent to those found in response to IGF-I. Both IGFs exert these effects though the same signalling pathways (MAPK and PI3K/Akt).

Myogenesis of skeletal muscles in vertebrates is controlled by extracellular signalling molecules together with intracellular transcription factors. Among the transcriptional factors, the members of the myogenic regulatory family, including MyoD, Myf5, Myogenin and MRF4, play important roles regulating skeletal muscle development and growth. To characterize the gene structure and expression of fish myogenin, we have isolated the myogenin genomic gene and cDNA from gilthead seabream (Sparus aurata) and analyzed the genomic structure, pattern of expression and the regulation of muscle-specific expression. Sequence analysis revealed that the seabream myogenin shares a similar gene structure with other fish myogenins, with three exons, two introns and the highly conserved bHLH domain. Expression studies demonstrated that myogenin is expressed in both slow and fast muscles as well as in muscle cells in primary culture. In situ hybridization showed that myogenin was specifically expressed in developing somites of seabream embryos. Promoter activity analysis demonstrated that the myogenin promoter could drive green fluorescence protein expression in muscle cells of zebrafish embryos, as well as in myofibers of adult zebrafish and juvenile seabream. Deletion analysis demonstrated that this muscle-specific activity depends on the presence of a MEF2 and a MEF3 binding site within the 550 bp myogenin promoter sequence.

The focus of this review is the response of insulin and glucagon to various experimental and physiological conditions in fish. Circulating levels of insulin and glucagon have been analyzed in several fish species, principally salmonids. It is generally accepted that, in fish, the insulin secretion in response to amino acids is stronger than to glucose, although this information has been obtained mainly from carnivorous species. Studies of other species demonstrate that the alimentary pattern affect hormonal secretion and should be taken into account when the effects of secretagogues are analyzed. There are few studies of glucagon secretion, even in salmonids, although it is known that amino acids also stimulate its release. The level of this response and its relationship to insulin secretion depends upon the species of fish. We will discuss the significance of these observations, while also considering other important factors, including the influence of neuropeptides and interactions with other pancreatic and gastro-intestinal hormones. Finally, seasonal, temperature and reproductive stage effects will be discussed, all of which should be taken into account when attempting to understand the role of pancreatic hormones in fish. This short review will not cover the action of these hormones on their target tissues.

The aim of this study was to characterise a primary cell culture isolated from fast skeletal muscle of the gilthead sea bream. Gene expression profiles during culture maturation were compared with those obtained from a fasting-refeeding model which is widely used to modulate myogenesis in vivo. Myogenesis is controlled by numerous extracellular signals together with intracellular transcriptional factors whose coordinated expression is critical for the appropriate development of muscle fibres. Full-length cDNAs for the transcription factors Myf5, Mrf4, Pax7 and Sox8 were cloned and sequenced for gilthead sea bream. Pax7, sox8, myod2 and myf5 levels were up-regulated during the proliferating phase of the myogenic cultures coincident with the highest expression of proliferating cell nuclear antigen (PCNA). In contrast, myogenin and mrf4 transcript abundance was highest during the differentiation phase of the culture when myotubes were present, and was correlated with increased myosin heavy chain (mhc) and desmin expression. In vivo, 30days of fasting resulted in muscle fibre atrophy, a reduction in myod2, myf5 and igf1 expression, lower number of Myod-positive cells, and decreased PCNA protein expression, whereas myogenin expression was not significantly affected. Myostatin1 (mstn1) and pax7 expression were up-regulated in fasted relative to well-fed individuals, consistent with a role for Pax7 in the reduction of myogenic cell activity with fasting. The primary cell cultures and fasting-feeding experiments described provide a foundation for the future investigations on the regulation of muscle growth in gilthead sea bream.

The chondroitin sulfate proteoglycan core protein aggrecan is the major protein constituent of cartilage aside from collagen, and is largely responsible for its distinctive mechanical properties. Aggrecan is required both for proper cartilage formation in development and maintenance of mature cartilage. Prominent Acan transcription is a conserved feature of vertebrate cartilage, although little is known about its specific transcriptional regulation. We examined the genomic interval containing human ACAN for transcriptional enhancers directing expression to cartilage, using a functional assay in transgenic zebrafish. We tested 24 conserved non-coding sequences, representing ~6% of the total sequence in the interval, and identified eleven independently capable of regulating reporter gene expression in cartilage. These enhancers were widely spaced, from >100 kb upstream of the gene to within the first intron. While the majority displayed broad cartilage expression in zebrafish larvae, several were restricted to a subset of cartilage cells in the craniofacial skeleton. In older fish, the enhancers displayed differential activity; some maintained expression, either in all cartilage or preferentially in articular cartilage at the joints, while others were not active. This remarkable degree of overlapping regulatory control has been highly conserved; we identified clear orthologues of six enhancers at the chicken ACAN locus, arranged in the same order relative to the gene. These were also functional in directing expression to cartilage in transgenic zebrafish. Several enhancers contain potential binding sites for Sox9, consistent with its described role as an upstream regulator of Acan expression. However, others lacked Sox9 consensus binding sites, implicating additional pathways and transcription factors as regulators of Acan expression in cartilage, either in development or adult tissue. Our identification of these enhancer sequences is the necessary first step in detailed examination of the upstream regulators of Acan expression.

Inspired by studies demonstrating the potential for new myocyte formation within adult mammalian hearts, an ongoing explosion of research is elucidating the biology of cardiac myogenesis and angiogenesis. Multiple lines of research suggest that disease-associated activation of endogenous cardiac repair processes are often insufficient to overcome the cell death resulting from myocardial infarction and chronic heart failure. In this context, this review highlights current evidence supporting endogenous cardiac repair mechanisms in human hearts, recent progress with clinical application of myocardial cell therapy, and complementary efforts to manipulate endogenous myocardial repair processes using a variety of tissue engineering strategies. The goal of this overview is to demonstrate that the insights and opportunities derived from each of these lines of inquiry are mutually complementary for ultimately achieving the goal of therapeutic cardiac regeneration.

In this study, primary cultures of trout skeletal muscle cells were used to investigate the main signal transduction pathways of insulin and IGF-I receptors in rainbow trout muscle. At different stages of in vitro development (myoblasts on day 1, myocytes on day 4, and fully developed myotubes on day 11), we detected in these cells the presence of immunoreactivity against ERK 1/2 MAPK and Akt/PKB proteins, components of the MAPK and the phosphatidylinositol 3-kinase-Akt pathways, respectively, two of the main intracellular transduction pathways for insulin and IGF-I receptors. Both insulin and IGF-I activated both pathways, although the latter provoked higher immunoreactivity of phosphorylated MAPKs and Akt proteins. At every stage, increases in total MAPK immunoreactivity levels were observed when cells were stimulated with IGF-I or insulin, while total Akt immunoreactivity levels changed little under stimulation of peptides. Total Akt and total MAPK levels increased as skeletal muscle cells differentiated in culture. Moreover, when cells were incubated with IGF-I or insulin, MAPK-P immunoreactivity levels showed greater increases over the basal levels on days 1 and 4, with no effect observed on day 11. Although Akt-P immunoreactivity displayed improved responses on days 1 and 4 as well, a stimulatory effect was still observed on day 11. In addition, the present study demonstrates that purified trout insulin receptors possess higher phosphorylative activity per unit of receptor than IGF-I receptors. In conclusion, these results indicate that trout skeletal muscle culture is a suitable model to study the insulin and IGF-I signal transduction molecules and that there is a different regulation of MAPK and Akt pathways depending on the developmental stage of the muscle cells.

The relative function of IGF-I and insulin on fish muscle metabolism and growth has been investigated by the isolation and culture at different stages (myoblasts at day 1, myocytes at day 4, and myotubes at day 10) of rainbow trout muscle cells. This in vitro model avoids interactions with endogenous peptides, which could interfere with the muscle response. In these cells, the effects of IGF-I and insulin on cell proliferation, 2-deoxyglucose (2-DG), and l-alanine uptake at different development stages, and the use of inhibitors were studied and quantified. Insulin (10-1,000 nM) and IGF-I (10-100 nM) stimulated 2-DG uptake in trout myocytes at day 4 in a similar manner (maximum of 124% for insulin and of 142% for IGF-I), and this stimulation increased when cells differentiated to myotubes (maximum for IGF-I of 193%). When incubating the cells with PD-98059 and especially cytochalasin B, a reduction in 2-DG uptake was observed, suggesting that glucose transport takes place through specific facilitative transporters. IGF-I (1-100 nM) stimulated the l-alanine uptake in myocytes at day 4 (maximum of 239%), reaching higher values of stimulation than insulin (100-1,000 nM) (maximum of 160%). This stimulation decreased when cells developed to myotubes at day 10 (118% for IGF-I and 114% for insulin). IGF-I (0.125-25 nM) had a significant effect on myoblast proliferation, measured by thymidine incorporation (maximum of 170%), and required the presence of 2-5% fetal serum (FBS) to promote thymidine uptake. On the other hand, insulin was totally ineffective in stimulating thymidine uptake. We conclude that IGF-I is more effective than insulin in stimulating glucose and alanine uptake in rainbow trout myosatellite cells and that the degree of stimulation changes when cells differentiate to myotubes. IGF-I stimulates cell proliferation in this model of muscle in vitro and insulin does not. These results indicate the important role of IGF-I on growth and metabolism of fish muscle.