The Long and Winding Road to Real-Life Experiments: Remote Assessment of Executive Functions with Computerized Games-Results from 8 Years of Naturalistic Interventions.

Mate Marote is an open-access cognitive training software aimed at children between 4 and 8 years old. It consists of a set of computerized games specifically tailored to train and evaluate Executive Functions (EF), a class of processes critical for purposeful, goal-directed behavior, including working memory, planning, flexibility, and inhibitory control. Since 2008, several studies were performed with this software at children's own schools in interventions supervised in-person by cognitive scientists. After 2015, we incorporated naturalistic, yet controlled, interventions with children's own teachers' help. The platform includes a battery of standardized tests, disguised as games, to assess children's EF. The main question that emerges is whether the results, obtained with these traditional tasks but conducted without the presence of researchers, are comparable to those widely reported in the literature, that were obtained in more supervised settings. In this study, we were able to replicate the expected difficulty and age effects in at least one of the analyzed dependent variables of each employed test. We also report important discrepancies between the expected and the observed response time patterns, specifically for time-constrained tasks. We hereby discuss the benefits and setbacks of a new possible strategy for this type of assessment in naturalistic settings. We conclude that this battery of established EF tasks adapted for its remote usage is appropriate to measure the expected mental processes in naturalistic settings, enriching opportunities to upscale cognitive training interventions at schools. These types of tools can constitute a concerted strategy to bring together educational neuroscience research and real-life practice.

Socioeconomic status differences in children's affective decision-making: The role of awareness in the Children's Gambling Task.

Future-oriented decision-making is an important adaptive behavior. In the present study, we examined whether decision-making varies as a function of socioeconomic status (SES) using the Children's Gambling task (CGT). We administered the CGT to 227 children (49% female, 48% low SES) between the ages of 5 and 7 years. After completing the CGT, we assessed children's knowledge of the reward/loss contingencies. Data analysis was conducted through multilevel modeling. Fluid intelligence, as measured by the Test of Nonverbal Intelligence, was included as a covariate in the analysis. Overall performance differed between SES groups. Children from middle/high-SES backgrounds learned to choose more from the deck with higher future reward. In contrast, children in the low-SES group did not act in a full future-oriented manner. No differences were found in the level of explicit understanding of the task reached by the two SES groups. Whereas middle/high-SES children with higher knowledge of the game performed better on the last blocks of the task in comparison with their same-SES peers with no understanding, low-SES children with higher explicit knowledge did not exhibit an improvement in their decision-making strategy in comparison with their same-SES low-awareness counterparts. Fluid intelligence did not predict CGT performance, suggesting that SES differences were not mediated by reasoning capabilities. The finding that children from low-SES families continued exhibiting an immediate reward-oriented strategy despite being aware of deck contingencies fits with (although speculatively) the evolutionary-developmental framework. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Partial agreement between task and BRIEF-P-based EF measures depends on school socioeconomic status.

Executive functions (EF), either conceptualized as skills involved in regulation of cognition and emotion in service of goal-oriented behavior, or reductively as working memory, flexibility and inhibitory control, are commonly invoked constructs in developmental science. Two main traditions on EFs measurement prevail, one consisting of ratings obtained through questionnaires that inquire on behavior in common situations, the other based on performance in laboratory tasks. Whether both types of assessment actually refer to the same constructs is not consensual. Further, the role of school context in the degree of correspondence between both types of measures remains largely unexplored. Here, we show in a sample of over 220 children (age M = 5.6, SD = 0.4 years), by means of multilevel models, that whether EF tasks can predict BRIEF-P ratings and vice-versa, depends on the process considered and on the school SES. Inhibitory control, planning, and global executive functioning are associated with BRIEF-P ratings in all schools. In contrast, we found no association among measures of flexibility independently of school SES. For working memory, we found that questionnaire rating predicts span only in high SES schools, but span predicts behaviors across schools. Our findings contribute to a growing body of literature that proposes constructs assessed by questionnaires and tasks only partially overlap and suggests that school SES may be a relevant factor to consider when questionnaires are answered by teachers.

CD38 Dictates Age-Related NAD Decline and Mitochondrial Dysfunction through an SIRT3-Dependent Mechanism.

Nicotinamide adenine dinucleotide (NAD) levels decrease during aging and are involved in age-related metabolic decline. To date, the mechanism responsible for the age-related reduction in NAD has not been elucidated. Here we demonstrate that expression and activity of the NADase CD38 increase with aging and that CD38 is required for the age-related NAD decline and mitochondrial dysfunction via a pathway mediated at least in part by regulation of SIRT3 activity. We also identified CD38 as the main enzyme involved in the degradation of the NAD precursor nicotinamide mononucleotide (NMN) in vivo, indicating that CD38 has a key role in the modulation of NAD-replacement therapy for aging and metabolic diseases.

Food Restriction Ameliorates the Development of Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder characterized by the accumulation of kidney cysts that ultimately leads to loss of renal function and kidney failure. At present, the treatment for ADPKD is largely supportive. Multiple studies have focused on pharmacologic approaches to slow the development of the cystic disease; however, little is known about the role of nutrition and dietary manipulation in PKD. Here, we show that food restriction (FR) effectively slows the course of the disease in mouse models of ADPKD. Mild to moderate (10%-40%) FR reduced cyst area, renal fibrosis, inflammation, and injury in a dose-dependent manner. Molecular and biochemical studies in these mice indicate that FR ameliorates ADPKD through a mechanism involving suppression of the mammalian target of the rapamycin pathway and activation of the liver kinase B1/AMP-activated protein kinase pathway. Our data suggest that dietary interventions such as FR, or treatment that mimics the effects of such interventions, may be potential and novel preventive and therapeutic options for patients with ADPKD.

SIRT1-Activating Compounds (STAC) Negatively Regulate Pancreatic Cancer Cell Growth and Viability Through a SIRT1 Lysosomal-Dependent Pathway.

PURPOSE: Recent studies suggest that SIRT1-activating compounds (STAC) are a promising class of anticancer drugs, although their mechanism of action remains elusive. The main goal of this study is to determine the role of STACs as a potential therapy for pancreatic cancer. In addition, we also explored the mechanism by which these compounds affect pancreatic cancer. EXPERIMENTAL DESIGN: Using in vitro (cell culture experiments) and in vivo (xenograft experiments) approaches, we studied the role of SIRT1 agonists (STAC) in human pancreatic cancer cell viability and growth. RESULTS: We show that SIRT1 is highly expressed in pancreatic cancer cells and that the STACs SRT1720, SRT1460, and SRT3025 inhibited cell growth and survival of pancreatic cancer cells. STACs enhanced the sensitivity of pancreatic cells to gemcitabine and paclitaxel, indicating that these drugs could be used in combination with other chemotherapy drugs. We also show that STACs were very effective in inhibiting tumor xenograft growth. In mechanistic studies, we observed that STACs activated a SIRT1 lysosomal-dependent cell death. Furthermore, the effect of STACs on cell viability was also dependent on the expression of the endogenous SIRT1 inhibitor DBC1. CONCLUSIONS: Taken together, our results reveal an essential role for SIRT1 and lysosomes in the death pathway regulated by STACs in pancreatic cancer cells. Clin Cancer Res; 22(10); 2496-507. ©2015 AACR.

Cardiomyopathy and Worsened Ischemic Heart Failure in SM22-α Cre-Mediated Neuropilin-1 Null Mice: Dysregulation of PGC1α and Mitochondrial Homeostasis.

OBJECTIVE: Neuropilin-1 (NRP-1) is a multidomain membrane receptor involved in angiogenesis and development of neuronal circuits, however, the role of NRP-1 in cardiovascular pathophysiology remains elusive. APPROACH AND RESULTS: In this study, we first observed that deletion of NRP-1 induced peroxisome proliferator-activated receptor γ coactivator 1α in cardiomyocytes and vascular smooth muscle cells, which was accompanied by dysregulated cardiac mitochondrial accumulation and induction of cardiac hypertrophy- and stress-related markers. To investigate the role of NRP-1 in vivo, we generated mice lacking Nrp-1 in cardiomyocytes and vascular smooth muscle cells (SM22-α-Nrp-1 KO), which exhibited decreased survival rates, developed cardiomyopathy, and aggravated ischemia-induced heart failure. Mechanistically, we found that NRP-1 specifically controls peroxisome proliferator-activated receptor γ coactivator 1 α and peroxisome proliferator-activated receptor γ in cardiomyocytes through crosstalk with Notch1 and Smad2 signaling pathways, respectively. Moreover, SM22-α-Nrp-1 KO mice exhibited impaired physical activities and altered metabolite levels in serum, liver, and adipose tissues, as demonstrated by global metabolic profiling analysis. CONCLUSIONS: Our findings provide new insights into the cardioprotective role of NRP-1 and its influence on global metabolism.

Deleted in breast cancer 1 limits adipose tissue fat accumulation and plays a key role in the development of metabolic syndrome phenotype.

Obesity is often regarded as the primary cause of metabolic syndrome. However, many lines of evidence suggest that obesity may develop as a protective mechanism against tissue damage during caloric surplus and that it is only when the maximum fat accumulation capacity is reached and fatty acid spillover occurs into to peripheral tissues that metabolic diseases develop. In this regard, identifying the molecular mechanisms that modulate adipocyte fat accumulation and fatty acid spillover is imperative. Here we identify the deleted in breast cancer 1 (DBC1) protein as a key regulator of fat storage capacity of adipocytes. We found that knockout (KO) of DBC1 facilitated fat cell differentiation and lipid accumulation and increased fat storage capacity of adipocytes in vitro and in vivo. This effect resulted in a "healthy obesity" phenotype. DBC1 KO mice fed a high-fat diet, although obese, remained insulin sensitive, had lower free fatty acid in plasma, were protected against atherosclerosis and liver steatosis, and lived longer. We propose that DBC1 is part of the molecular machinery that regulates fat storage capacity in adipocytes and participates in the "turn-off" switch that limits adipocyte fat accumulation and leads to fat spillover into peripheral tissues, leading to the deleterious effects of caloric surplus.

Deleted in Breast Cancer 1 regulates cellular senescence during obesity.

Chronic obesity leads to inflammation, tissue dysfunction, and cellular senescence. It was proposed that cellular senescence during obesity and aging drives inflammation and dysfunction. Consistent with this, clearance of senescent cells increases healthspan in progeroid mice. Here, we show that the protein Deleted in Breast Cancer-1 (DBC1) regulates cellular senescence during obesity. Deletion of DBC1 protects preadipocytes against cellular senescence and senescence-driven inflammation. Furthermore, we show protection against cellular senescence in DBC1 KO mice during obesity. Finally, we found that DBC1 participates in the onset of cellular senescence in response to cell damage by mechanism that involves binding and inhibition of HDAC3. We propose that by regulating HDAC3 activity during cellular damage, DBC1 participates in the fate decision that leads to the establishment of cellular senescence and consequently to inflammation and tissue dysfunction during obesity.

Deleted in breast cancer 1 (DBC1) protein regulates hepatic gluconeogenesis.

Liver gluconeogenesis is essential to provide energy to glycolytic tissues during fasting periods. However, aberrant up-regulation of this metabolic pathway contributes to the progression of glucose intolerance in individuals with diabetes. Phosphoenolpyruvate carboxykinase (PEPCK) expression plays a critical role in the modulation of gluconeogenesis. Several pathways contribute to the regulation of PEPCK, including the nuclear receptor Rev-erbα and the histone deacetylase SIRT1. Deleted in breast cancer 1 (DBC1) is a nuclear protein that binds to and regulates both Rev-erbα and SIRT1 and, therefore, is a candidate to participate in the regulation of PEPCK. In this work, we provide evidence that DBC1 regulates glucose metabolism and the expression of PEPCK. We show that DBC1 levels decrease early in the fasting state. Also, DBC1 KO mice display higher gluconeogenesis in a normal and a high-fat diet. DBC1 absence leads to an increase in PEPCK mRNA and protein expression. Conversely, overexpression of DBC1 results in a decrease in PEPCK mRNA and protein levels. DBC1 regulates the levels of Rev-erbα, and manipulation of Rev-erbα activity or levels prevents the effect of DBC1 on PEPCK. In addition, Rev-erbα levels decrease in the first hours of fasting. Finally, knockdown of the deacetylase SIRT1 eliminates the effect of DBC1 knockdown on Rev-erbα levels and PEPCK expression, suggesting that the mechanism of PEPCK regulation is, at least in part, dependent on the activity of this enzyme. Our results point to DBC1 as a novel regulator of gluconeogenesis.

Targeting of NAD metabolism in pancreatic cancer cells: potential novel therapy for pancreatic tumors.

PURPOSE: Here, we describe a novel interplay between NAD synthesis and degradation involved in pancreatic tumor growth. EXPERIMENTAL DESIGN: We used human pancreatic cancer cells, both in vitro (cell culture experiments) and in vivo (xenograft experiments), to demonstrate the role of NAD synthesis and degradation in tumor cell metabolism and growth. RESULTS: We demonstrated that pharmacologic and genetic targeting of Nampt, the key enzyme in the NAD salvage synthesis pathway, inhibits cell growth and survival of pancreatic cancer cells. These changes were accompanied by a reduction of NAD levels, glycolytic flux, lactate production, mitochondrial function, and levels of ATP. The massive reduction in overall metabolic activity induced by Nampt inhibition was accompanied by a dramatic decrease in pancreatic tumor growth. The results of the mechanistic experiments showed that neither the NAD-dependent enzymes PARP-1 nor SIRT1 play a significant role on the effect of Nampt inhibition on pancreatic cancer cells. However, we identified a role for the NAD degradation pathway mediated by the NADase CD38 on the sensitivity to Nampt inhibition. The responsiveness to Nampt inhibition is modulated by the expression of CD38; low levels of this enzyme decrease the sensitivity to Nampt inhibition. In contrast, its overexpression decreased cell growth in vitro and in vivo, and further increased the sensitivity to Nampt inhibition. CONCLUSIONS: Our study demonstrates that NAD metabolism is essential for pancreatic cancer cell survival and proliferation and that targeting NAD synthesis via the Nampt pathway could lead to novel therapeutic treatments for pancreatic cancer.

Deleted in breast cancer-1 (DBC-1) in the interface between metabolism, aging and cancer.

DBC1 (deleted in breast cancer-1) is a nuclear protein that regulates cellular metabolism. Since alteration in cellular metabolism have been proposed to be the emerging 'hallmark' of cancer, it is possible that DBC1 may be implicated in the regulation of cancer cell energy metabolism. However, at this point any role of DBC1 in cancer is only speculative. In this review, we will discuss the new developments in DBC1 research, its molecular structure, regulatory roles and implication in metabolism, aging and cancer.

DBC1 (Deleted in Breast Cancer 1) modulates the stability and function of the nuclear receptor Rev-erbα.

The nuclear receptor Rev-erbα has been implicated as a major regulator of the circadian clock and integrates circadian rhythm and metabolism. Rev-erbα controls circadian oscillations of several clock genes and Rev-erbα protein degradation is important for maintenance of the circadian oscillations and also for adipocyte differentiation. Elucidating the mechanisms that regulate Rev-erbα stability is essential for our understanding of these processes. In the present paper, we report that the protein DBC1 (Deleted in Breast Cancer 1) is a novel regulator of Rev-erbα. Rev-erbα and DBC1 interact in cells and in vivo, and DBC1 modulates the Rev-erbα repressor function. Depletion of DBC1 by siRNA (small interfering RNA) in cells or in DBC1-KO (knockout) mice produced a marked decrease in Rev-erbα protein levels, but not in mRNA levels. In contrast, DBC1 overexpression significantly enhanced Rev-erbα protein stability by preventing its ubiquitination and degradation. The regulation of Rev-erbα protein levels and function by DBC1 depends on both the N-terminal and C-terminal domains of DBC1. More importantly, in cells depleted of DBC1, there was a dramatic decrease in circadian oscillations of both Rev-erbα and BMAL1. In summary, our data identify DBC1 as an important regulator of the circadian receptor Rev-erbα and proposes that Rev-erbα could be involved in mediating some of the physiological effects of DBC1.

Flavonoid apigenin is an inhibitor of the NAD+ ase CD38: implications for cellular NAD+ metabolism, protein acetylation, and treatment of metabolic syndrome.

Metabolic syndrome is a growing health problem worldwide. It is therefore imperative to develop new strategies to treat this pathology. In the past years, the manipulation of NAD(+) metabolism has emerged as a plausible strategy to ameliorate metabolic syndrome. In particular, an increase in cellular NAD(+) levels has beneficial effects, likely because of the activation of sirtuins. Previously, we reported that CD38 is the primary NAD(+)ase in mammals. Moreover, CD38 knockout mice have higher NAD(+) levels and are protected against obesity and metabolic syndrome. Here, we show that CD38 regulates global protein acetylation through changes in NAD(+) levels and sirtuin activity. In addition, we characterize two CD38 inhibitors: quercetin and apigenin. We show that pharmacological inhibition of CD38 results in higher intracellular NAD(+) levels and that treatment of cell cultures with apigenin decreases global acetylation as well as the acetylation of p53 and RelA-p65. Finally, apigenin administration to obese mice increases NAD(+) levels, decreases global protein acetylation, and improves several aspects of glucose and lipid homeostasis. Our results show that CD38 is a novel pharmacological target to treat metabolic diseases via NAD(+)-dependent pathways.

Role of deleted in breast cancer 1 (DBC1) protein in SIRT1 deacetylase activation induced by protein kinase A and AMP-activated protein kinase.

The NAD(+)-dependent deacetylase SIRT1 is a key regulator of several aspects of metabolism and aging. SIRT1 activation is beneficial for several human diseases, including metabolic syndrome, diabetes, obesity, liver steatosis, and Alzheimer disease. We have recently shown that the protein deleted in breast cancer 1 (DBC1) is a key regulator of SIRT1 activity in vivo. Furthermore, SIRT1 and DBC1 form a dynamic complex that is regulated by the energetic state of the organism. Understanding how the interaction between SIRT1 and DBC1 is regulated is therefore essential to design strategies aimed to activate SIRT1. Here, we investigated which pathways can lead to the dissociation of SIRT1 and DBC1 and consequently to SIRT1 activation. We observed that PKA activation leads to a fast and transient activation of SIRT1 that is DBC1-dependent. In fact, an increase in cAMP/PKA activity resulted in the dissociation of SIRT1 and DBC1 in an AMP-activated protein kinase (AMPK)-dependent manner. Pharmacological AMPK activation led to SIRT1 activation by a DBC1-dependent mechanism. Indeed, we found that AMPK activators promote SIRT1-DBC1 dissociation in cells, resulting in an increase in SIRT1 activity. In addition, we observed that the SIRT1 activation promoted by PKA and AMPK occurs without changes in the intracellular levels of NAD(+). We propose that PKA and AMPK can acutely activate SIRT1 by inducing dissociation of SIRT1 from its endogenous inhibitor DBC1. Our experiments provide new insight on the in vivo mechanism of SIRT1 regulation and a new avenue for the development of pharmacological SIRT1 activators targeted at the dissociation of the SIRT1-DBC1 complex.

Early and late calcium waves during wound healing in corneal endothelial cells.

Immediately after wounding, bovine corneal endothelial cells develop a fast calcium wave that propagates from the wound border to the rest of the monolayer and extinguishes in approximately 5 minutes. One hour after wounding, a late, slow calcium wave (SCW) develops concomitantly to the depolarization of the plasma membrane potential of the border cells. The incorporation of inhibitors of the epithelial sodium channel and of the sodium-calcium exchanger produces inhibition of the membrane depolarization and the SCW, and diminishes the rate of wound healing. The L-type calcium channel blocker nimodipine does not have any effect on the SCW. The reversible inhibition of the fast calcium wave does not affect the SCW and only slightly decreases the velocity of healing. Our results suggest that the SCW is at least partially produced by the coupling of the epithelial sodium channel and the sodium-calcium exchanger functioning in reverse mode. They also suggest that the SCW may play a role in the overall healing process.

Altered behavioral and metabolic circadian rhythms in mice with disrupted NAD+ oscillation.

The Intracellular levels of nicotinamide adenine dinucleotide (NAD(+)) are rhythmic and controlled by the circadian clock. However, whether NAD(+) oscillation in turn contributes to circadian physiology is not fully understood. To address this question we analyzed mice mutated for the NAD(+) hydrolase CD38. We found that rhythmicity of NAD(+) was altered in the CD38-deficient mice. The high, chronic levels of NAD(+) results in several anomalies in circadian behavior and metabolism. CD38-null mice display a shortened period length of locomotor activity and alteration in the rest-activity rhythm. Several clock genes and, interestingly, genes involved in amino acid metabolism were deregulated in CD38-null livers. Metabolomic analysis identified alterations in the circadian levels of several amino acids, specifically tryptophan levels were reduced in the CD38-null mice at a circadian time paralleling with elevated NAD(+) levels. Thus, CD38 contributes to behavioral and metabolic circadian rhythms and altered NAD(+) levels influence the circadian clock.

HDAC3 is negatively regulated by the nuclear protein DBC1.

HDAC3 is a member of the class I histone deacetylase family that regulates gene expression by deacetylation of histones and non-histone proteins. HDAC3 activity has been shown to be modulated by interaction with the co-repressors NCoR and SMRT. Here, we present evidence that the nuclear protein DBC1 is an endogenous inhibitor of HDAC3. DBC1 has been previously identified as a regulator of some nuclear receptors, the methyltransferase SUV39H1, and the NAD-dependent deacetylase SIRT1. Furthermore, DBC1 has been shown to influence transcription regulation and apoptosis, and it may also act as a tumor suppressor. We found that DBC1 interacts and specifically inhibits the deacetylase HDAC3. This interaction depends on the N terminus of DBC1 and the C terminus of HDAC3. Expression of DBC1 not only inhibited HDAC3 activity but also altered its subcellular distribution. In addition, knockdown of endogenous DBC1 in cells and knock-out in mouse tissues increased HDAC3 deacetylase activity. Together, these results identify DBC1 as a new regulator of HDAC3 and demonstrate that DBC1 is a negative regulator of two key distinct deacetylases, SIRT1 and HDAC3. These findings may lead to a better understanding of the biological roles of DBC1 and HDAC3 in metabolic diseases and cancer.

CD38 expression, function, and gene resequencing in a human lymphoblastoid cell line-based model system.

CD38 is an ecto-enzyme that hydrolyzes NAD. Its expression is a prognostic marker for chronic lymphocytic leukemia. We have characterized individual variation in CD38 expression in lymphoblastoid cell lines from 288 healthy subjects of three ethnicities. Expression varied widely, with significant differences among ethnic groups, and was correlated significantly with CD38 enzymatic activity and protein levels. The CD38 gene was then resequenced using DNA from the same cell lines, with the identification of 53 single nucleotide polymorphisms (SNPs) and one indel, 39 novel. One SNP, rs1130169, was significantly associated with CD38 mRNA expression and explained a portion of the difference in expression among ethnic groups. EMS assay showed nuclear protein binding at or near this SNP. We also determined that variation in CD38 expression in these cell lines was associated with variation in antineoplastic drug sensitivity. These results represent a step toward understanding mechanisms involved in CD38 expression.

Deleted in breast cancer-1 regulates SIRT1 activity and contributes to high-fat diet-induced liver steatosis in mice.

The enzyme sirtuin 1 (SIRT1) is a critical regulator of many cellular functions, including energy metabolism. However, the precise mechanisms that modulate SIRT1 activity remain unknown. As SIRT1 activity in vitro was recently found to be negatively regulated by interaction with the deleted in breast cancer-1 (DBC1) protein, we set out to investigate whether DBC1 regulates SIRT1 activity in vivo. We found that DBC1 and SIRT1 colocalized and interacted, and that DBC1 modulated SIRT1 activity, in multiple cell lines and tissues. In mouse liver, increased SIRT1 activity, concomitant with decreased DBC1-SIRT1 interaction, was detected after 24 hours of starvation, whereas decreased SIRT1 activity and increased interaction with DBC1 was observed with high-fat diet (HFD) feeding. Consistent with the hypothesis that DBC1 is crucial for HFD-induced inhibition of SIRT1 and for the development of experimental liver steatosis, genetic deletion of Dbc1 in mice led to increased SIRT1 activity in several tissues, including liver. Furthermore, DBC1-deficient mice were protected from HFD-induced liver steatosis and inflammation, despite the development of obesity. These observations define what we believe to be a new role for DBC1 as an in vivo regulator of SIRT1 activity and liver steatosis. We therefore propose that the DBC1-SIRT1 interaction may serve as a new target for therapies aimed at nonalcoholic liver steatosis.