Faculty Bibliography

Accumulating evidence suggests that epigenetic alterations in brain-derived neurotrophic factor (BDNF) promoters are associated with the pathophysiology of psychiatric disorders. Epigenetic changes in BDNF were reported not only in brain tissues but also in other tissues, including peripheral blood cells (PBC) and saliva. We examined DNA methylation levels of BDNF promoters I and IV using genomic DNA derived from PBC of healthy controls (n=100), and patients with schizophrenia (n=100), all from the Japanese population, by pyrosequencing. The examined CpG sites were chosen based on previous epigenetic studies that reported altered DNA methylation. We found a significantly higher level of methylation at BDNF promoter I in patients with schizophrenia compared to controls, although the difference was small. Subsequent analysis revealed that in controls, the methylation level of BDNF promoters was associated with sex, and the methylation difference observed in promoter I was more prominent in male patients with schizophrenia. Epigenetic alteration of BDNF in the PBC might reflect the pathophysiology of schizophrenia, and could be a potential biomarker.

The Janus kinase/Signal transducers and activators of transcription (JAK/STAT) pathway determines cell fates by regulating gene expression. One example is the specification of the motile cells called border cells during Drosophila oogenesis. It has been established that too much or too little STAT activity disrupts follicle cell identity and cell motility, which suggests the signaling must be precisely regulated. Here, we find that Suppressor of cytokine signaling at 36E (Socs36E) is a necessary negative regulator of JAK/STAT signaling during border cell specification. We find when STAT signaling is too low to induce migration in the presumptive border cell population, nearby follicle cells uncharacteristically become invasive to enable efficient migration of the cluster. We generated a genetic null allele that reveals Socs36E is required in the anterior follicle cells to limit invasive behavior to an optimal number of cells. We further show Socs36E genetically interacts with the required STAT feedback inhibitor apontic (apt) and APT's downstream target, mir-279, and provide evidence that suggests APT directly regulates Socs36E transcriptionally. Our work shows Socs36E plays a critical role in a genetic circuit that establishes a boundary between the motile border cell cluster and its non-invasive epithelial neighbors through STAT attenuation.

BACKGROUND: Seventy-five million people are estimated to be hypertensive in sub-Saharan Africa. This translates in high morbidity and mortality, as hypertension is now considered to be the number one single risk factor for death worldwide. Accurate data from countries lacking national disease surveillance is needed to guide future evidence-driven health policies. The authors aimed to estimate the prevalence, awareness, management and control of hypertension and associated factors in an adult population of Angola. METHODS: A community-based survey of 1,464 adults, following the World Health Organization's Stepwise Approach to Chronic Disease Risk Factor Surveillance, was conducted to estimate the prevalence of hypertension, awareness, treatment and control in Dande, Northern Angola. Using a demographic surveillance system database, a representative sample of subjects, stratified by sex and age (18-40 and 41-64 years old), was selected. RESULTS: Prevalence of hypertension (systolic blood pressure >/=140 mmHg and/or diastolic blood pressure >/=90 mmHg and/or hypertensive therapy) was of 23% (95% CI: 21% to 25.2%). A follow-up consultation confirmed the hypertensive status in 82% of the subjects who had a second measurement on average 23 days after the first. Amongst hypertensive individuals, 21.6% (95% CI: 17.0% to 26.9%) were aware of their status. Only 13.9% (95% CI: 5.9% to 29.1%) of the subjects aware of their condition were under pharmacological treatment, of which approximately one-third were controlled. Older age, lower level of education, higher body mass index and abdominal obesity were found to be significantly (p<0.01) associated with hypertension. CONCLUSIONS: Our survey is the first to provide insightful data on hypertension prevalence in Angola. There is an urgent need for strategies to improve prevention, diagnosis and access to adequate treatment in this country, where a massive economic growth and consequent potential impact on lifestyle risk factors could lead to an increase in the prevalence of hypertension and cardiovascular disease.

BACKGROUND: Accurate identification of Plasmodium infections in community surveys is essential to successful malaria control. Microscopy and rapid diagnostic tests (RDTs) are the main techniques used to diagnose malaria in field-based surveys. While microscopy is still considered the gold standard, RDTs are growing in popularity as they allow for rapid and inexpensive diagnosis. Using data from a prevalence survey conducted in north-western Angola in 2010, the authors aimed to compare the performance of microscopy and RDTs in identifying Plasmodium falciparum infections, using polymerase chain reaction (PCR) as the gold standard. METHODS: Results from 3,307 subjects (1,225 preschool-aged children (zero to five year olds), 1,134 school-aged children (six to 15 year olds) and 948 mothers/caregivers (>15 years of age)), tested for P. falciparum infections, were utilized. The sensitivity, specificity, positive, and negative predictive values (PPV and NPV) of microscopy and Paracheck-Pf(R) were compared using the McNemar's test and the weighted generalized score Chi-squared test for paired data. RESULTS: The prevalence of P. falciparum infections determined by PCR and microscopy was 15.9% and by Paracheck- Pf(R) was 16.3%. Compared to microscopy, Paracheck-Pf(R) had significantly higher sensitivity (72.8% versus 60%), specificity (94.3% versus 92.5%), PPV (70.7% versus 60%) and NPV (94.8% versus 92.5%). Both tests had significantly lower sensitivity in mothers (36.8% for microscopy and 43.7% for Paracheck-Pf(R)) than in their children (68.4% in zero to five years-old and 60.6% in six to 15 years-old for microscopy and 80.4% in zero to five year-olds and 76.5% in six to 15 year-olds for Paracheck-Pf(R)). CONCLUSION: Both microscopy and RDTs performed suboptimally when compared to PCR. False negativity could be associated with the low parasite density profile of the samples. False positivity may be related to the well-described limitations of those techniques such as level of expertise of microscopists or persistent antigenicity from previous infections in the case of RDTs. Nevertheless, RDTs had enhanced performance comparatively to microscopy in detecting malaria infections, favouring their use in community cross-sectional malaria surveys, where expert performance of microscopy is hard to accomplish.

OBJECTIVE: Lymphangiogenesis is regulated by transcription factors and by growth factor pathways, but their interplay has not been extensively studied so far. We addressed this issue in zebrafish. APPROACH AND RESULTS: Mutations in the transcription factor-coding gene SOX18 and in VEGFR3 cause lymphedema, and the VEGFR3/Flt4 ligand VEGFC plays an evolutionarily conserved role in lymphangiogenesis. Here, we report a strong genetic interaction between Sox18 and VegfC in the early phases of lymphatic development in zebrafish. Knockdown of sox18 selectively impaired lymphatic sprouting from the cardinal vein and resulted in defective lymphatic thoracic duct formation. Sox18 and the related protein Sox7 play redundant roles in arteriovenous differentiation. We used a novel transgenic line that enables inducible expression of a dominant-negative mutant form of mouse Sox18 protein. Our data led us to conclude that Sox18 is crucially involved in lymphangiogenesis after arteriovenous differentiation. Combined partial knockdown of sox18 and vegfc, using subcritical doses of specific morpholinos, revealed a synergistic interaction in both venous and lymphatic sprouting from the cardinal vein and greatly impaired thoracic duct formation. CONCLUSIONS: This interaction suggests a previously unappreciated crosstalk between the growth factor and transcription factor pathways that regulate lymphangiogenesis in development and disease.

BACKGROUND: The cardiac intercalated disc (ID) has been extensively studied by conventional transmission electron microscopy (EM). Yet, novel methods for tissue preservation (high-pressure freezing), image (3D tomographic EM) and analysis (image segmentation) that greatly improve image quality/resolution, have not been applied to the ID. Recent studies show that, at the ID, the gap junction protein Connexin43 is part of an interactome (a "connexome"). Here, we provide a structural characterization of the connexome. METHODS: Adult mouse ventricular tissue was prepared by high-pressure freezing and freeze substitution and embedded in resin. 200 nm thick sections were imaged with a 200kV electron microscope (FEI TF20). Images were collected at a set magnification of 9.6k on a 4kx4k CCD camera set to 2x binning, giving an effective pixel size of 1.76 nm. Dual-axis tilt series (1 masculine steps, +/-70 masculine per axis) were acquired using SerialEM. Protomo software was used for aligning projection images and reconstructing tomograms. Visualization/segmentation of objects of interest was performed in Amira. RESULTS: In addition to classic ID structures, we observed (a) close proximity between gap junctions and mitochondria of opposing cells; (b) a complex network of tubular structures running perpendicular to the long cell axis; these structures showed a hollow interior, with an estimated inner diameter of ~40 nm and were often adjacent to gap junctions or desmosomes; (c) triads formed by lateral edges of gap junctions and desmosomes, with a rough budding vesicle separating the two structures; (d) budding vesicles of approximately 50 nm interrupting the continuity of one side of the gap junction plaque; (e) vesicular bodies of approx. 65 nm in diameter in the intercellular space, and in proximity to gap junction-containing regions. CONCLUSIONS: We describe the nanometric landscape that surrounds gap junctions. We speculate that the connexome includes a physical association with molecules of the mitochondria, desmosome and microtubular network, and propose that microsomes may pass from one cell to another at the ID. Functional characterization of these structures may lead to novel clues as to the mechanisms of inherited or acquired arrhythmias that involve disruption of the ID.