Hypothalamic Npy mRNA is correlated with increased wheel running and decreased body fat in calorie-restricted rats.

The neuro-molecular mechanisms that regulate the relationship between physical activity level, energy homeostasis regulation, and body fat are unclear. Thus, we aimed to investigate the relationship between mRNAs in the hypothalamic arcuate nucleus (ARC) related to energy homeostasis, wheel running distance, and body fat in ad lib (AL) and calorie-restricted (CR) growing rats. We hypothesized that changes in select mRNAs (Pomc, Cart, Agrp, Npy, Lepr, Insr, Mc4r, Ampk, Sirt1, Sirt3) in CR would be associated with decreases in body fat percentage and increased wheel running behavior. Male Wistar rats were given access to voluntary running wheels at 4 weeks of age and randomized into AL (n=8) and CR (70% of AL; n=7) groups at 5 weeks of age until study termination at 12 weeks of age. Body composition, serum leptin, insulin, and adiponectin, and ARC mRNA expression in AL and CR rats were assessed and correlated with week-12 running distance to examine potential relationships that may exist. By 12 weeks of age, wheel running was increased ∼3.3-fold (p=0.03) while body fat percentage was ∼2-fold lower in CR compared to AL (p=0.001). Compared to AL, ARC Npy mRNA expression was ∼2-fold greater in CR (p=0.02), while Lepr, Insr, Ampk, and Sirt1 mRNA were additionally increased in CR (p<0.05). Significant correlations existed between ARC Npy mRNA levels versus week-12 wheel running distance (r=0.81, p=0.03), body fat (r=-0.93, p<0.01), and between body fat and wheel running (r=-0.83, p=0.02) in CR, but not in AL. These results reveal possible mechanisms by which fat-brain crosstalk may influence physical activity during energy deficit. These data suggest that below a 'threshold' fat content, body fat may drive activity levels, potentially through hypothalamic Npy action.

Control of vascular tube morphogenesis and maturation in 3D extracellular matrices by endothelial cells and pericytes.

An important advance using in vitro EC tube morphogenesis and maturation models has been the development of systems using serum-free defined media. Using this approach, the growth factors and cytokines which are actually necessary for these events can be determined. The first model developed by our laboratory was such a system where we showed that phorbol ester was needed in order to promote survival and tube morphogenesis in 3D collagen matrices. Recently, we have developed a new system in which the hematopoietic stem cell cytokines, stem cell factor (SCF), interleukin-3 (IL-3), and stromal derived factor-1α (SDF-1α) were added in conjunction with FGF-2 to promote human EC tube morphogenesis in 3D collagen matrices under serum-free defined conditions. This new model using SCF, IL-3, SDF-1α, and FGF-2 also works well following the addition of pericytes where EC tube formation occurs, pericytes are recruited to the tubes, and vascular basement membrane matrix assembly occurs following EC-pericyte interactions. In this chapter, we describe several in vitro assay models that we routinely utilize to investigate the molecular requirements that are critical to EC tube formation and maturation events in 3D extracellular matrix environments.

The neuropilin 1 cytoplasmic domain is required for VEGF-A-dependent arteriogenesis.

Neuropilin 1 (NRP1) plays an important but ill-defined role in VEGF-A signaling and vascular morphogenesis. We show that mice with a knockin mutation that ablates the NRP1 cytoplasmic tail (Nrp1(cyto)) have normal angiogenesis but impaired developmental and adult arteriogenesis. The arteriogenic defect was traced to the absence of a PDZ-dependent interaction between NRP1 and VEGF receptor 2 (VEGFR2) complex and synectin, which delayed trafficking of endocytosed VEGFR2 from Rab5+ to EAA1+ endosomes. This led to increased PTPN1 (PTP1b)-mediated dephosphorylation of VEGFR2 at Y(1175), the site involved in activating ERK signaling. The Nrp1(cyto) mutation also impaired endothelial tubulogenesis in vitro, which could be rescued by expressing full-length NRP1 or constitutively active ERK. These results demonstrate that the NRP1 cytoplasmic domain promotes VEGFR2 trafficking in a PDZ-dependent manner to regulate arteriogenic ERK signaling and establish a role for NRP1 in VEGF-A signaling during vascular morphogenesis.

The radish gene reveals a memory component with variable temporal properties.

Memory phases, dependent on different neural and molecular mechanisms, strongly influence memory performance. Our understanding, however, of how memory phases interact is far from complete. In Drosophila, aversive olfactory learning is thought to progress from short-term through long-term memory phases. Another memory phase termed anesthesia resistant memory, dependent on the radish gene, influences memory hours after aversive olfactory learning. How does the radish-dependent phase influence memory performance in different tasks? It is found that the radish memory component does not scale with the stability of several memory traces, indicating a specific recruitment of this component to influence different memories, even within minutes of learning.