Catalan beauty and the transnational beast: Barcelona on screen

This article explores the case of Barcelona as paradigmatic global city in such transnational productions as Vicky Cristina Barcelona by Woody Allen (2008) and Biutiful by Alejandro González Iñárritu (2010). Allen"s film shows the extreme dilution that national and linguistic identity undergoes under foreign eyes in its rendition of a"hip Barcelona" for tourists"invaded" by transnational subjects in search of bourgeois pleasures. Maybe in pursuit of a more"real" city, Iñárritu"s Biutiful moves to the Barcelona of the immigrants and the undocumented, a transnational and paradoxical location inhabited by those who need to cross borders in order to survive. Through reference to the work of Manuel Castells, Saskia Sassen, Neil Smith and Michel De Certeau among others, we argue that neither of these representations of the city is more real or unreal than the other. In their drastically divergent ways, both films contribute their external perspectives to the imaginary construction of Barcelona as a fascinating global city and can be seen as a dyptich of a transnational Barcelona. Further, they contribute to the ongoing debate about the polarization between the local and the global, the construction of urban boarders inside cities through gentrification, the transformation of the places we (would like to) inhabit, and the translation of all these into visual terms.

Notch signaling is a direct determinant of keratinocyte growth arrest and entry into differentiation.

The role of Notch signaling in growth/differentiation control of mammalian epithelial cells is still poorly defined. We show that keratinocyte-specific deletion of the Notch1 gene results in marked epidermal hyperplasia and deregulated expression of multiple differentiation markers. In differentiating primary keratinocytes in vitro endogenous Notch1 is required for induction of p21WAF1/Cip1 expression, and activated Notch1 causes growth suppression by inducing p21WAF1/Cip1 expression. Activated Notch1 also induces expression of 'early' differentiation markers, while suppressing the late markers. Induction of p21WAF1/Cip1 expression and early differentiation markers occur through two different mechanisms. The RBP-Jkappa protein binds directly to the endogenous p21 promoter and p21 expression is induced specifically by activated Notch1 through RBP-Jkappa-dependent transcription. Expression of early differentiation markers is RBP-Jkappa-independent and can be induced by both activated Notch1 and Notch2, as well as the highly conserved ankyrin repeat domain of the Notch1 cytoplasmic region. Thus, Notch signaling triggers two distinct pathways leading to keratinocyte growth arrest and differentiation.

The peroxisome proliferator-activated receptors at the cross-road of diet and hormonal signalling.

The peroxisome proliferator-activated receptors (PPARs) are members of the steroid/thyroid nuclear receptor superfamily of ligand-activated transcription factors. To date, three isotypes have been identified, alpha, beta and gamma, encoded by three different genes. The alpha isotype is expressed at high levels in the liver where it has a role in lipid oxidation. Its expression and activity follow a diurnal rhythm that parallels the circulating levels of corticosterone in the bloodstream. The gamma isotype on the other hand, is mainly expressed in adipose tissue and has a critical role in adipocyte differentiation and lipid storage. The function of the ubiquitously expressed isotype, PPAR beta, remains to be determined. Besides fulfilling different roles in lipid metabolism, the different PPAR isotypes also have different ligand specificities. A new approach to identify ligands was developed based on the ligand-dependent interaction of PPAR with the recently characterized co-activator SRC-1. This so-called CARLA assay has allowed the identification of fatty acids and eicosanoids as PPAR ligands. Although the evidence clearly links PPAR isotypes to distinct functions, the molecular basis for this isotype-specificity is still unclear. All three isotypes are able to bind the same consensus response element, formed by a direct repeat of two AGGTCA hexamers separated by one base, though with different affinities. We recently demonstrated that besides the core DR-1 element, the 5' flanking sequence should be included in the definition of a PPRE. Interestingly, the presence of this flanking sequence is of particular importance in the context of PPAR alpha binding. Moreover, it reflects the polarity of the PPAR-RXR heterodimer on DNA, with PPAR binding to the 5' half-site and RXR binding to the 3' half-site. This unusual polarity may confer unique properties to the bound heterodimer with respect to ligand binding and interaction with co-activators and corepressors.

Silencing of both beta-TrCP1 and HOS (beta-TrCP2) is required to suppress human immunodeficiency virus type 1 Vpu-mediated CD4 down-modulation.

The human immunodeficiency virus type 1 (HIV-1) Vpu protein interacts with CD4 within the endoplasmic reticula of infected cells and targets CD4 for degradation through interaction with beta-TrCP1. Mammals possess a homologue of beta-TrCP1, HOS, which is also named beta-TrCP2. We show by coimmunoprecipitation experiments that beta-TrCP2 binds Vpu and is able to induce CD4 down-modulation as efficiently as beta-TrCP1. In two different cell lines, HeLa CD4+ and Jurkat, Vpu-mediated CD4 down-modulation could not be reversed through the individual silencing of endogenous beta-TrCP1 or beta-TrCP2 but instead required the two genes to be silenced simultaneously.

Mutation patterns of amino acid tandem repeats in the human proteome

Background: Amino acid tandem repeats are found in nearly one-fifth of human proteins. Abnormal expansion of these regions is associated with several human disorders. To gain further insight into the mutational mechanisms that operate in this type of sequence, we have analyzed a large number of mutation variants derived from human expressed sequence tags (ESTs).Results: We identified 137 polymorphic variants in 115 different amino acid tandem repeats. Of these, 77 contained amino acid substitutions and 60 contained gaps (expansions or contractions of the repeat unit). The analysis showed that at least about 21% of the repeats might be polymorphic in humans. We compared the mutations found in different types of amino acid repeats and in adjacent regions. Overall, repeats showed a five-fold increase in the number of gap mutations compared to adjacent regions, reflecting the action of slippage within the repetitive structures. Gap and substitution mutations were very differently distributed between different amino acid repeat types. Among repeats containing gap variants we identified several disease and candidate disease genes.Conclusion: This is the first report at a genome-wide scale of the types of mutations occurring in the amino acid repeat component of the human proteome. We show that the mutational dynamics of different amino acid repeat types are very diverse. We provide a list of loci with highly variable repeat structures, some of which may be potentially involved in disease.

Comparative analysis of amino acid repeats in rodents and humans

Amino acid tandem repeats, also called homopolymeric tracts, are extremely abundant in eukaryotic proteins. To gain insight into the genome-wide evolution of these regions in mammals, we analyzed the repeat content in a large data set of rat-mouse-human orthologs. Our results show that human proteins contain more amino acid repeats than rodent proteins and that trinucleotide repeats are also more abundant in human coding sequences. Using the human species as an outgroup, we were able to address differences in repeat loss and repeat gain in the rat and mouse lineages. In this data set, mouse proteins contain substantially more repeats than rat proteins, which can be at least partly attributed to a higher repeat loss in the rat lineage. The data are consistent with a role for trinucleotide slippage in the generation of novel amino acid repeats. We confirm the previously observed functional bias of proteins with repeats, with overrepresentation of transcription factors and DNA-binding proteins. We show that genes encoding amino acid repeats tend to have an unusually high GC content, and that differences in coding GC content among orthologs are directly related to the presence/absence of repeats. We propose that the different GC content isochore structure in rodents and humans may result in an increased amino acid repeat prevalence in the human lineage.

Dissecting the role of low-complexity regions in the evolution of vertebrate proteins

Low-complexity regions (LCRs) in proteins are tracts that are highly enriched in one or a few aminoacids. Given their high abundance, and their capacity to expand in relatively short periods of time through replication slippage, they can greatly contribute to increase protein sequence space and generate novel protein functions. However, little is known about the global impact of LCRs on protein evolution. We have traced back the evolutionary history of 2,802 LCRs from a large set of homologous protein families from H.sapiens, M.musculus, G.gallus, D.rerio and C.intestinalis. Transcriptional factors and other regulatory functions are overrepresented in proteins containing LCRs. We have found that the gain of novel LCRs is frequently associated with repeat expansion whereas the loss of LCRs is more often due to accumulation of amino acid substitutions as opposed to deletions. This dichotomy results in net protein sequence gain over time. We have detected a significant increase in the rate of accumulation of novel LCRs in the ancestral Amniota and mammalian branches, and a reduction in the chicken branch. Alanine and/or glycine-rich LCRs are overrepresented in recently emerged LCR sets from all branches, suggesting that their expansion is better tolerated than for other LCR types. LCRs enriched in positively charged amino acids show the contrary pattern, indicating an important effect of purifying selection in their maintenance. We have performed the first large-scale study on the evolutionary dynamics of LCRs in protein families. The study has shown that the composition of an LCR is an important determinant of its evolutionary pattern.

Experience-dependent plasticity in the mouse barrel cortex

Abstract : Host-Cell Factor 1 (HCF-1) was first discovered in the study of the herpes simplex virus (HSV) infection. HCF-1 is one of the two cellular proteins that compose the VP16-induced complex, a key activator of HSV lytic infection. lncleed, when HSV infects human cells, it is able to enter two modes of infection: lytic or latent. The V`P16-induced complex promotes the lytic mode and in so doing the virus targets important cellular regulatory proteins, such as HCF-1, to manipulate the status of the infected cell. Indeed, HCF-1 regulates human cell proliferation and the cell cycle at different steps. In human, HCF-1 is unusual in that it undergoes a process of proteolytic maturation that results from cleavages at six centrally located 26 amino acid repeats called HCF-1pro repeats. This generates a heterodimeric complex of stably associated amino- (HCF-1n) and carboxy- (HCF-1c) terminal subunits. The absence of the HCF-1 N or HCF-1; subunit leads predominantly to either G1 or M phase defects, respectively. We have hypothesized that HCF-1 forms a heterodimeric complex to permit communication between the two subunits of HCF-1 involved in regulating different phases of the cell cycle. Indeed, there is evidence for such inter-subunit communication because a point mutation called P134S in the HCF-1N subunit in the temperature-sensitive hamster cell line tsBN67 causes, addition to G1- phase defects associated with the HCF-1n subunit, M-phase defects similar to the defects seen upon loss of HCF-1 function. Furthermore, inhibition of the proteolytic maturation of HCF-1 by deletion of the six HCF-1pro repeats (HCF-1Aimo) also leads to M-phase defects, specifically cytokinesis defects leading to binucleation, indicating that there is loss of HCF-15 function in the absence of HCF-1 maturation. I demonstrate that individual point mutations in each of the six HCF-1pro repeats that prevent HCF-1 proteolytic maturation also lead to binucleation; however, this defect can be latgely rescued by the presence of just one HCF-1pRO sequence in I-ICF»1. These results argue that processing itself is important for the HCF-1g function. In fact, until now, the hypothesis was that the proteolytic processing per se is more important for HCF-1C function than the proteolytic processing region. But I show that processing per se is not sufticient to rescue multinucleation, but that the HCF-lpm sequence itself is crucial. This discovery leads to the conclusion that the I-ICF-1pRO repeats have an additional function important for HCF-le function. From the studies of others, one potential function of the HCF-lrxo tepeats is as a binding site for O-link NAcetyl glycosamine tansferase (OGT) to glycosylate an HCF-1n-sunbunit region called the Basic region. This new function suggests the Basic region of HCF-1n is also implicated in the communication between the two subunits. This inter-subunit communication was analyzed in more detail with the studies of the Pl34S mutation and the residues 382-450 region of HCF-l that when removed prevents HCF-l subunit association. I demonstrate that the point mutation also leads to a binucleation defect in Hela cells as well as in the tsBN67 cells. In addition, the effect of this mutation on the regulation of HCF-1c activity seems to interfere with that of the HCF-lpgg repeats because the sum of the deletion of the proteolytic processing region and the point mutation surprisingly leads to re-establishment of correct cytokinesis. The study of the 382-450 HCF-lN region also yielded surprising results. This region important for the association of the two subunits is also important for both HCF-1c function in M phase and G1 phase progression. Thus, I have discovered two main functions of this region: its role in the regulation of HCF-lc function in M phase and its involvement in the regulation of G1/S phase ?- an HCF-1n function. These results support the importance of inter-subunit communication in HCF-1 functions. My research illuminates the understanding of the interaction of the two subunits by showing that the whole HCF-1n subunit is involved in the inter-subunit communication in order to regulate HCF-1c function. For this work, I was concentrated on the study of cytokinesis; the first phenotype showing the role of HCF-1c in the M phase. Then, I extended the study of the M phase with analysis of steps earlier to cytokinesis. Because some defects in the chromosome segregation was already described in the absence of HCF-1, I decided to continue the study of M phase by checking effects on the chromosome segregation. I showed that the HCF-1n subunit and HCF-1pro repeats are both important for this key step of M phase. I show that the binucleation phenotype resulting from deletion or mutation in HCF-1pro repeats, Pl34S point mutation or the lack of the region 382-450 are correlated with micronuclei, and chromosome segregation and alignment defects. This suggests that HCF«lç already regulates M phase during an early step and could be involved in the complex regulation of chromosome segregation. Because one of the major roles of HCF-1 is to be a transcription regulator, I also checked the capacity of HCF-1 to bind to the chromatin in my different cell lines. All my recombinant proteins can bind the chromatin, except for, as previously described, the HCF-1 with the P134S point mutation, This suggests that the binding of HCF-1 to the chromatin is not dependant to the Basic and proteolytic regions but more to the Kelch domain. Thus, if the function of HCF-ig in M phase is dependant to its chromatin association, the intercommunication and the proteolytic region are not involved in the ability to bind to the chromatin but more to bind to the right place of the chromatin or to be associated with the co-factors. Résumé : L'étude de l'infection par le virus Herpes Simplex (HSV) a permis la découverte de la protéine HCF-1 (Host-Cell Factor). HCF-1 est une des protéines cellulaires qui font partie du complexe induit par VP16 ; ce complexe est la clef pour l'activation de la phase lytique de HSV. Afin de manipuler les cellules infectées, le complexe induit pas le VPIG devrait donc cibler les protéines importantes pour la régulation cellulaire, telles que la protéine HCF-1. Cette dernière s'avère donc être un senseur pour la cellule et devrait également jouer un rôle de régulation lors des différentes phases du cycle cellulaire. Chez l'humain, HCF-1 a la particularité de devoir passer par une phase de maturation pour devenir active. Lors de cette maturation, la protéine subit une coupure protéolytique au niveau de six répétitions composées de 26 acides aminés, appelé HCF-1pro repeats. Cette coupure engendre la formation d'un complexe formé de deux sous-unités, HCF-1n et HCF-1c, associées l'une à l'autre de façon stable. Enlever la sous-unité HCF-IN ou C entraîne respectivement des défauts dans la phase G1 et M. Nous pensons donc que HCF-1 forme un complexe hétérodimérique afin de permettre la communication entre les molécules impliquées dans la régulation des différentes phases du cycle cellulaire. Cette hypothèse est déduite suite à deux études: l'une réalisée sur la lignée cellulaire tsBN67 et l'autre portant sur l'inhibition de la maturation protéolytique. La lignée cellulaire tsBN67, sensible à la température, porte la mutation Pl 345 dans la sous-unité HCF-1n. Cette mutation, en plus d'occasionner des défauts dans la phase G1 (défauts liés à la sous-unité HCF-1N), a aussi pour conséquence d'entrainer des défauts dans la phase M, défauts similaires à ceux dus a la perte de la sous-unité HCF-1c. Quant à la maturation protéolytique, l'absence de la région de la protéolyse provoque la binucléation, défaut lié à la cytokinèse, indiquant la perte de la fonction de la sous-unité HCF-1c. Au cours de ma thèse, j'ai démontré que des mutations dans les HCF-1=no repeats, qui bloquent la protéolyse, engendrent la binucléation ; cependant ce défaut peut être corrigé pas l'ajout d'un HCF-1pro repeat dans un HCF-1 ne contenant pas la région protéolytique. Ces résultats soutiennent l'idée que la région protéolytique est importante pour le bon fonctionnement de HCF-1c. En réalité jusqu'a maintenant on supposait que le mécanisme de coupure était plus important que la région impliquée pour la régulation de la fonction de HCF-1;. Mais mon étude montre que la protéolyse n'est pas suffisante pour éviter la binucléation ; en effet, les HCF-1pro repeats semblent jouer le rôle essentiel dans le cycle cellulaire. Cette découverte conduit à la conclusion que les HCF-1pro repeats ont sûrement une fonction autre qui serait cruciale pour la foncton de HCF-1c. Une des fonctions possibles est d'être le site de liaison de l'O-linked N-acetylglucosamine transférase (OGT) qui glycosylerait la région Basique de HCF-1n. Cette nouvelle fonction suggère que la région Basique est aussi impliquée dans la communication entre les deux sous- unités. L'intercommunication entre les deux sous-unités ai été d'ailleurs analysée plus en détail dans mon travail à travers l'étude de la mutation Pl34S et de la région 382-450, essentielle pour l'association des deux sous»unités. J'ai ainsi démontré que la mutation P134S entraînait aussi des défauts dans la cytokinése dans la lignée cellulaire Hela, de plus, son influence sur HCF-1c semble interférer avec celle de la région protéolytique. En effet, la superposition de ces deux modifications dans HCF-1 conduit au rétablissement d'une cytokinése correcte. Concernant la région 382 à 450, les résultats ont été assez surprenants, la perte de cette région provoque l'arrêt du cycle en G1 et la binucléation, ce qui tend à prouver son importance pour le bon fonctionnement de HCF-1n et de HCF-1c. Cette découverte appuie par conséquent l'hypotl1èse d'une intercommunicatzion entre les deux sous-unités mettant en jeu les différentes régions de HCF-1n. Grâce à mes recherches, j'ai pu améliorer la compréhension de l'interaction des deux sous-unités de HCF-1 en montrant que toutes les régions de HCF-1n sont engagées dans un processus d'intercommunication, dont le but est de réguler l'action de HCF-1c. J'ai également mis en évidence une nouvelle étape de la maturation de HCF-1 qui représente une phase importante pour l'activation de la fonction de HCF-1c. Afin de mettre à jour cette découverte, je me suis concentrée sur l'étude de l'impact de ces régions au niveau de la cytokinése qui fut le premier phénotype démontrant le rôle de HCF-1c dans la phase M. A ce jour, nous savons que HCF-1c joue un rôle dans la cytokinèse, nous ne connaissons pas encore sa fonction précise. Dans le but de cerner plus précisément cette fonction, j'ai investigué des étapes ultérieures ai la cytokinèse. Des défauts dans la ségrégation des chromosomes avaient déjà été observés, ai donc continué l'étude en prouvant que HCF-1n et les HCF-1pro repeats sont aussi importants pour le bon fonctionnement de cette étape clef également régulée par HCF-1c. J' ai aussi montré que la région 382-450 et la mutation P134S sont associées à un taux élevé de micronoyaux, de défauts dans la ségrégation des chromosomes. L'une des fonctions principales de HCF-1 étant la régulation de la transcription, j'ai aussi contrôlé la capacité de HCF-1 à se lier à la chromatine après insertion de mutations ou délétions dans HCF-1n et dans la région protéolytique. Or, à l'exception des HCF-1 contenant la mutation P134S, la sous-unité HCF-1c des HCF-1 tronquées se lie correctement à la chromatine. Cette constatation suggère que la liaison entre HCF-1c et chromatine n'est pas dépendante de la région Basique ou Protéolytique mais peut-être vraisemblablement de la région Kelch. Donc si le rôle de HCF-1c est dépendant de sa capacité â activer la transcription, l'intercommunication entre les deux sous-unités et la région protéolytique joueraient un rôle important non pas dans son habileté à se lier à la chromatine, mais dans la capacité de HCF-1 à s'associer aux co-facteurs ou à se placer sur les bonnes régions du génome.

Role of reactive hyperreninemia in blood pressure changes induced by sodium depletion in patients with refractory hypertension

Sixteen patients with refractory hypertension were submitted to vigorous sodium depletion while cardiovascular homeostasis was monitored with measurements of hormonal and hemodynamic parameters and repeat saralasin tests. This regimen resulted in a negative sodium balance by an average of 300 mEq. The loss of sodium closely correlated to the decrease of body weight (r = 0.70, p less than 0.005). Blood pressure (BP) decreased from 176/166 +/- 8/3 to 155/109 +/-6/3 mm Hg. There was a significant correlation between percent increments in plasma renin activity (PRA) and the rise in plasma norepinephrine (r = 0.68, p less than 0.05) and a close negative correlation between percent increase in PRA and the ratio of fall in mean blood pressure (MAP) per unit of weight loss (r = -0.73, p less than 0.005). Thus, patients with the least percent increase in PRA demonstrated the greatest fall in BP per unit of weight loss, indicating that relative rather than absolute elevation of renin may be the factor limiting antihypertensive efficacy of sodium depletion. Sodium depletion induced increase in peripheral resistance and decrease in cardiac output, both mostly attributable to relative hyperreninemia. Indeed, the adverse hemodynamic changes were reversed by angiotensin inhibition, during which BP normalized. It is concluded that vigorous sodium depletion complemented by angiotensin blockade or suppression with sympatholytic agents improves management of otherwise refractory hypertension.

Molecular cloning of a novel human I-mfa domain-containing protein that differently regulates human T-cell leukemia virus type I and HIV-1 expression.

Regulation of viral genome expression is the result of complex cooperation between viral proteins and host cell factors. We report here the characterization of a novel cellular factor sharing homology with the specific cysteine-rich C-terminal domain of the basic helix-loop-helix repressor protein I-mfa. The synthesis of this new factor, called HIC for Human I-mfa domain-Containing protein, is controlled at the translational level by two different codons, an ATG and an upstream non-ATG translational initiator, allowing the production of two protein isoforms, p32 and p40, respectively. We show that the HIC protein isoforms present different subcellular localizations, p32 being mainly distributed throughout the cytoplasm, whereas p40 is targeted to the nucleolus. Moreover, in trying to understand the function of HIC, we have found that both isoforms stimulate in T-cells the expression of a luciferase reporter gene driven by the human T-cell leukemia virus type I-long terminal repeat in the presence of the viral transactivator Tax. We demonstrate by mutagenesis that the I-mfa-like domain of HIC is involved in this regulation. Finally, we also show that HIC is able to down-regulate the luciferase expression from the human immunodeficiency virus type 1-long terminal repeat induced by the viral transactivator Tat. From these results, we propose that HIC and I-mfa represent two members of a new family of proteins regulating gene expression and characterized by a particular cysteine-rich C-terminal domain.

Protection against Plasmodium falciparum challenge induced in Aotus monkeys by liver-stage antigen-3-derived long synthetic peptides.

The vaccine potential of Plasmodium falciparum liver stage antigen-3 (LSA3) was investigated in Aotus monkeys using two long synthetic peptides corresponding respectively to an N-terminal non-repeat peptide (NRP) and repeat 2 (R2) region of the LSA3, adjuvanted by ASO2. Both 100-222 (NRP) and 501-596 repeat peptides induced effector B- and T-cell responses in terms of antigen-driven antibodies and/or specific IFN-gamma secretion. Animals challenged with P. falciparum sporozoites were protected following immunization with either the NRP region alone or the NRP combined with the R2 repeat region, as compared with controls receiving the adjuvant alone. These results indicate that the NRP may be sufficient to induce full, sterile protection and confirm the vaccine potential of LSA3 previously demonstrated in chimpanzees and in Aotus.

Association between bipolar disorder and monoamine oxidase A gene polymorphisms: results of a multicenter study

OBJECTIVE: Although genetic factors have been implicated in the etiology of bipolar disorder, no specific gene has been conclusively identified. Given the link between abnormalities in serotonergic neurotransmission and bipolar disorder, a candidate gene association approach was applied to study the involvement of the monoamine oxidase A (MAOA) gene, which codes for a catabolic enzyme of serotonin, in the susceptibility to bipolar disorder. METHOD: In France and Switzerland, 272 patients with bipolar disorder and 122 healthy subjects were typed for three polymorphic markers of the MAOA gene: the MAOA-CA repeat, the MAOA restriction fragment length polymorphism (RFLP), and a repeat directly adjacent to the variable number of tandem repeats (VNTR) locus. RESULTS: A significant difference in the distribution of the alleles for the MAOA-CA repeat was observed between the female bipolar patients and comparison group. CONCLUSIONS: The results obtained in the French and Swiss population confirm findings from two studies conducted in the United Kingdom.

A pathogenic mechanism in Huntington"s disease involves small CAG-repeated RNAs with neurotoxic activity

Huntington's disease (HD) is an autosomal dominantly inherited disorder caused by the expansion of CAG repeats in the Huntingtin (HTT) gene. The abnormally extended polyglutamine in the HTT protein encoded by the CAG repeats has toxic effects. Here, we provide evidence to support that the mutant HTT CAG repeats interfere with cell viability at the RNA level. In human neuronal cells, expanded HTT exon-1 mRNA with CAG repeat lengths above the threshold for complete penetrance (40 or greater) induced cell death and increased levels of small CAG-repeated RNAs (sCAGs), of ≈21 nucleotides in a Dicer-dependent manner. The severity of the toxic effect of HTT mRNA and sCAG generation correlated with CAG expansion length. Small RNAs obtained from cells expressing mutant HTT and from HD human brains significantly decreased neuronal viability, in an Ago2-dependent mechanism. In both cases, the use of anti-miRs specific for sCAGs efficiently blocked the toxic effect, supporting a key role of sCAGs in HTT-mediated toxicity. Luciferase-reporter assays showed that expanded HTT silences the expression of CTG-containing genes that are down-regulated in HD. These results suggest a possible link between HD and sCAG expression with an aberrant activation of the siRNA/miRNA gene silencing machinery, which may trigger a detrimental response. The identification of the specific cellular processes affected by sCAGs may provide insights into the pathogenic mechanisms underlying HD, offering opportunities to develop new therapeutic approaches

Seleção tradicional e associada a marcadores moleculares na avaliação genética animal

O objetivo deste trabalho foi comparar a seleção, utilizando valores genéticos preditos pelo BLUP clássico (BLUP), BLUP marcadores (BLUPM) e pela seleção individual (SI), usando simulação com o programa Genesys. Para obter a matriz de similaridade genética utilizada no BLUPM, foram simulados cem marcadores moleculares do tipo microssatélite (SSR - Simple Sequence Repeat), por meio de um coeficiente de similaridade correspondente à distância euclideana média para dados quantitativos. A fim de comparar os diferentes métodos, utilizaram-se populações com tamanho efetivo de 66,66 e média de 30 repetições, avaliando-se os valores fenotípicos médios. Os ganhos ao longo das 20 gerações de seleção foram maiores para o BLUP em relação ao BLUPM, e este foi superior à SI. Quanto ao ganho obtido nas cinco primeiras gerações, o BLUPM apresentou ganhos semelhantes ao BLUP e superiores à SI. Diferentes sistemas de acasalamento dos reprodutores selecionados não revelaram diferenças em ganho genético nos métodos baseados no BLUP.

Telomere fluorescence measurements in granulocytes and T lymphocyte subsets point to a high turnover of hematopoietic stem cells and memory T cells in early childhood.

To study telomere length dynamics in hematopoietic cells with age, we analyzed the average length of telomere repeat sequences in diverse populations of nucleated blood cells. More than 500 individuals ranging in age from 0 to 90 yr, including 36 pairs of monozygous and dizygotic twins, were analyzed using quantitative fluorescence in situ hybridization and flow cytometry. Granulocytes and naive T cells showed a parallel biphasic decline in telomere length with age that most likely reflected accumulated cell divisions in the common precursors of both cell types: hematopoietic stem cells. Telomere loss was very rapid in the first year, and continued for more than eight decades at a 30-fold lower rate. Memory T cells also showed an initial rapid decline in telomere length with age. However, in contrast to naive T cells, this decline continued for several years, and in older individuals lymphocytes typically had shorter telomeres than did granulocytes. Our findings point to a dramatic decline in stem cell turnover in early childhood and support the notion that cell divisions in hematopoietic stem cells and T cells result in loss of telomeric DNA.