Pathways to decoding the clinical potential of stress response FOXO-interaction networks for Huntington's disease: of gene prioritization and context dependence

The FOXO family of transcription factors is central to the regulation of organismal longevity and cellular survival. Several studies have indicated that FOXO factors lie at the center of a complex network of upstream pathways, cofactors and downstream targets (FOXO-interaction networks), which may have developmental and post-developmental roles in the regulation of chronic-stress response in normal and diseased cells. Noticeably, FOXO factors are important for the regulation of proteotoxicity and neuron survival in several models of neurodegenerative disease, suggesting that FOXO-interaction networks may have therapeutic potential. However, the status of FOXO-interaction networks in neurodegenerative disease remains largely unknown. Systems modeling is anticipated to provide a comprehensive assessment of this question. In particular, interrogating the context-dependent variability of FOXO-interaction networks could predict the clinical potential of cellular-stress response genes and aging regulators for tackling brain and peripheral pathology in neurodegenerative disease. Using published transcriptomic data obtained from murine models of Huntington's disease (HD) and post-mortem brains, blood samples and induced-pluripotent-stem cells from HD carriers as a case example, this review briefly highlights how the biological status and clinical potential of FOXO-interaction networks for HD may be decoded by developing network and entropy based feature selection across heterogeneous datasets.

A microwave interferometer for small and tenuous plasma density measurements

The non-intrusive density measurement of the thin plasma produced by a mini-helicon space thruster (HPH.com project) is a challenge, due to the broad density range (between 10(16) m(-3) and 10(19) m(-3)) and the small size of the plasma source (2 cm of diameter). A microwave interferometer has been developed for this purpose. Due to the small size of plasma, the probing beam wavelength must be small (λ = 4 mm), thus a very high sensitivity interferometer is required in order to observe the lower density values. A low noise digital phase detector with a phase noise of 0.02° has been used, corresponding to a density of 0.5 × 10(16) m(-3).

Higher protein intake strategies in human milk fortification for preterms infants feeding. Auxological and neurodevelopmental outcome

Postnatal growth restriction and failure to thrive still remain a major problem in Extremely Low Birth Weight (ELBW) infants . The goal for the nutritional care of these infants is to achieve rate of growth similar to those of the fetus in utero at the equivalent gestational age. Human milk fortified remains the best food for all these preterms. Two groups of preterm of weight 580-1250 g and gestational age 23-32 wk, were fed with different protein intake in the human/maternal milk fortified ( 3,5 g Kg-1 per day and 4,8 g Kg-1 per day in the control and intervention group respectively).The feeding tolerance, intrahospital growth, neurological outcome and anthropometric data until 12 months of corrected age, were evaluated. The protein supplemented group (PSG) showed an intrahospital highter growth rate ( mostly in head circumference, p 0,02, and length growth, p 0,04) only in the preterms with 580-980 g and 23-30 wk. In the same preterms, Griffith Development Mental Score at 3 and 12 months corrected age showed higher score than in the control group in the Performance (p 0,04) and Hearing/Language (p 0,03) items. The auxological evaluation in the postdischarge period showed in the PSG group mean z-score values for length higher than those in the control group at 9 (p 0,04) months of corrected age.

Large-scale functional RNAi screen in C. elegans identifies genes that regulate the dysfunction of mutant polyglutamine neurons

BACKGROUND

A central goal in Huntington's disease (HD) research is to identify and prioritize candidate targets for neuroprotective intervention, which requires genome-scale information on the modifiers of early-stage neuron injury in HD.

RESULTS

Here, we performed a large-scale RNA interference screen in C. elegans strains that express N-terminal huntingtin (htt) in touch receptor neurons. These neurons control the response to light touch. Their function is strongly impaired by expanded polyglutamines (128Q) as shown by the nearly complete loss of touch response in adult animals, providing an in vivo model in which to manipulate the early phases of expanded-polyQ neurotoxicity. In total, 6034 genes were examined, revealing 662 gene inactivations that either reduce or aggravate defective touch response in 128Q animals. Several genes were previously implicated in HD or neurodegenerative disease, suggesting that this screen has effectively identified candidate targets for HD. Network-based analysis emphasized a subset of high-confidence modifier genes in pathways of interest in HD including metabolic, neurodevelopmental and pro-survival pathways. Finally, 49 modifiers of 128Q-neuron dysfunction that are dysregulated in the striatum of either R/2 or CHL2 HD mice, or both, were identified.

CONCLUSIONS

Collectively, these results highlight the relevance to HD pathogenesis, providing novel information on the potential therapeutic targets for neuroprotection in HD.

Role and Therapeutic Potential of the Pro-Longevity Factor FOXO and Its Regulators in Neurodegenerative Disease

Studies in simple model organisms have yielded crucial insights into the genetic and molecular aspects of longevity. FOXO, which is most notable for its association with longevity, and its upstream regulators such as sirtuins have received particular attention in translational research because these genes modulate cell survival in several models of neurodegenerative diseases. There is a large amount of knowledge on the pathways that regulate FOXO activity and genes that may be regulated by FOXO. However, for the same reason that the FOXO network is a complex stress response system, its therapeutic potential to develop disease-modifying strategies requires further examination. Although the FOXO network contains druggable genes such as sirtuins and AMPK, whether they should be activated or inhibited and whether protection against the early or late phases of neuronal cell decline might require opposite therapeutic strategies remains unclear. Additionally, the mode of action of small compound molecules believed to act on FOXO network targets was questioned. This review recapitulates essential facts and questions about the promises of FOXO and its interactors in neurodegenerative disease.

Absence of effects of Sir2 overexpression on lifespan in C. elegans and Drosophila

Overexpression of sirtuins (NAD(+)-dependent protein deacetylases) has been reported to increase lifespan in budding yeast (Saccharomyces cerevisiae), Caenorhabditis elegans and Drosophila melanogaster. Studies of the effects of genes on ageing are vulnerable to confounding effects of genetic background. Here we re-examined the reported effects of sirtuin overexpression on ageing and found that standardization of genetic background and the use of appropriate controls abolished the apparent effects in both C. elegans and Drosophila. In C. elegans, outcrossing of a line with high-level sir-2.1 overexpression abrogated the longevity increase, but did not abrogate sir-2.1 overexpression. Instead, longevity co-segregated with a second-site mutation affecting sensory neurons. Outcrossing of a line with low-copy-number sir-2.1 overexpression also abrogated longevity. A Drosophila strain with ubiquitous overexpression of dSir2 using the UAS-GAL4 system was long-lived relative to wild-type controls, as previously reported, but was not long-lived relative to the appropriate transgenic controls, and nor was a new line with stronger overexpression of dSir2. These findings underscore the importance of controlling for genetic background and for the mutagenic effects of transgene insertions in studies of genetic effects on lifespan. The life-extending effect of dietary restriction on ageing in Drosophila has also been reported to be dSir2 dependent. We found that dietary restriction increased fly lifespan independently of dSir2. Our findings do not rule out a role for sirtuins in determination of metazoan lifespan, but they do cast doubt on the robustness of the previously reported effects of sirtuins on lifespan in C. elegans and Drosophila.

Meclizine is neuroprotective in models of Huntington's disease

Defects in cellular energy metabolism represent an early feature in a variety of human neurodegenerative diseases. Recent studies have shown that targeting energy metabolism can protect against neuronal cell death in such diseases. Here, we show that meclizine, a clinically used drug that we have recently shown to silence oxidative metabolism, suppresses apoptotic cell death in a murine cellular model of polyglutamine (polyQ) toxicity. We further show that this protective effect extends to neuronal dystrophy and cell death in Caenorhabditis elegans and Drosophila melanogaster models of polyQ toxicity. Meclizine's mechanism of action is not attributable to its anti-histaminergic or anti-muscarinic activity, but rather, strongly correlates with its ability to suppress mitochondrial respiration. Since meclizine is an approved drug that crosses the blood-brain barrier, it may hold therapeutic potential in the treatment of polyQ toxicity disorders, such as Huntington's disease.

[Analysis of the evolution to defined connective tissue diseases of patients with "early unidifferentiated connective tissue diseases (UCTD)"]

The term undifferentiated connective tissue diseases (UCTD) is used to identify systemic autoimmune diseases not fulfilling classificative criteria for defined connective tissue diseases (CTD). Aim of the present study was to evaluate the evolution to defined CTD of an historical cohort of 91 UCTD patients followed at our Unit and to describe clinical and serological characteristics of stable UCTD patients with a disease duration of more than 5 years. Patients, previously described, were selected for having an undifferentiated profile after 1 year of follow up. These patients have been regularly followed at our Unit and their diagnosis has been reassessed annually based on the existing classificative criteria. Seven UCTD patients with a follow up of less than 5 years have been excluded from the study, therefore 84 patients (F: 81, M: 3) have been analysed. During the follow up 28 patients (33%) developed a defined CTD. In particular 22 patients developed systemic lupus erythematosus (SLE), while the remaining 6 patients developed other CTDs (2 primary Sjögren's syndrome, 2 overlap syndromes, 1 Systemic Sclerosis, 1 rheumatoid arthritis). The evolution to a defined CTD occurred after a mean disease duration of 80.6+/- 66.8 months (min 14, max 336, median 72); the evolution to SLE occurred after a mean disease duration of 66.8+/-43.3 months (min 17, max 216, median 57). Anti-cardiolipin antibodies were the only variable correlated with the evolution to SLE (p<0.05). Stable UCTD were characterized by a simplified clinical picture with no major organ involvement and by a simplified autoantibody profile (anti-Ro/SSA antibodies and anti-RNP antibodies were the single antibody specificities observed in 22% and 13% of patients respectively). These results confirm previous data showing that about 30% of UCTD patients will develop a defined CTD, the predictive role of anti-cardiolipin antibodies for the evolution to SLE, and the existence of stable UCTD, distinct clinical entities with a simplified clinico-serological profile. The early identification of stable UCTD is very important both from a clinical and a research point of view. Future research is needed to define a new set of classification criteria.

Undifferentiated connective tissue diseases (UCTD)

The term undifferentiated connective tissue diseases is used to define conditions characterized by the presence of signs and symptoms suggestive of a systemic autoimmune disease that do not satisfy the classificative criteria for defined connective tissue diseases (CTD) such as systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), rheumatoid arthritis (RA) and others. A small percentage of patients presenting with an undifferentiated profile will develop during the first year follow up of a full blown CTD, however an average of 75% will maintain an undifferentiated clinical course. These patients may be defined as having a stable undifferentiated connective tissue diseases (UCTD). The most characteristic symptoms of UCTD are represented by arthritis and arthralgias, Raynaud's phenomenon, leukopenia, while neurological and kidney involvement are virtually absent. Eighty percent of these patients have a single autoantibody specificity, more frequently anti-Ro and anti-RNP antibodies. Stable UCTD are considered as distinct clinical entities and therefore it has been proposed to define those conditions as UCTD. Classificative criteria have also been proposed and a work to better define them is still under way.

Quantitation of fetal DNA in maternal serum during the first trimester of pregnancy by the use of a DAZ repetitive probe

Cell-free fetal DNA in maternal plasma or serum is at present widely investigated as a source of fetal genetic material, both in studies of pregnancy-related disorders and in planning strategies for non-invasive prenatal diagnosis. Despite the number of trials already performed on the quantitation of fetal DNA, data about the amount of DNA at the beginning of pregnancy, in particular in the first trimester, remain limited. A new probe mapping on the deleted in azoospermia (DAZ) repetitive region of the Yq chromosome was designed for an early assessment of fetal DNA concentration in maternal serum. Among 57 pregnant women prospectively studied in their first trimester, fetal DNA was detected already by the 5th gestational week, with the analysis becoming reliable by the 8th week of gestation when a 100% accuracy in fetal sex determination was achieved. Moreover, in the three cases of pregnancy ending in fetal loss, the amount of fetal DNA apparently decreased before the abortion was diagnosed, whereas it consistently showed an increasing trend in normal pregnancies. Real-time PCR with the use of DAZ multilocus probe can efficiently quantitate free fetal DNA in the maternal serum at the beginning of pregnancy.