The neuroendocrine system governs essential survival and homeostatic functions. For example, growth is needed for development, thermoregulation maintains optimal core temperature in a changing environment, and reproduction ensures species survival. Stress and immune responses enable an organism to overcome external and internal threats while the circadian system regulates arousal and sleep such that vegetative and active functions do not overlap. All of these functions require a significant portion of the body's energy. As the integrator of the neuroendocrine system, the hypothalamus carefully assesses the energy status of the body in order to appropriately partition resources to provide for each system without compromising the others. While doing so the hypothalamus must ensure that adequate glucose levels are preserved for brain function since glucose is the primary fuel of the brain. To this end, the hypothalamus contains specialized glucose sensing neurons which are scattered throughout the nuclei controlling distinct neuroendocrine functions. We hypothesize that these neurons play a key role in enabling the hypothalamus to partition energy to meet these peripheral survival needs without endangering the brain's glucose supply. This review will first describe the varied mechanisms underlying glucose sensing in neurons within discrete hypothalamic nuclei. We will then evaluate the way in which peripheral energy status regulates glucose sensitivity. For example, during energy deficit such as fasting specific hypothalamic glucose sensing neurons become sensitized to decreased glucose. This increases the gain of the information relay when glucose availability is a greater concern for the brain. Finally, changes in glucose sensitivity under pathological conditions (e.g., recurrent insulin-hypoglycemia, diabetes) will be addressed. The overall goal of this review is to place glucose sensing neurons within the context of hypothalamic control of neuroendocrine function.
Fructose-bisphosphate aldolase A (ALDOA) is a key enzyme in glycolysis and is responsible for catalyzing the reversible conversion of fructose-1,6-bisphosphate to glyceraldehydes-3-phosphate and dihydroxyacetone phosphate. ALDOA contributes to various cellular functions such as muscle maintenance, regulation of cell shape and mobility, striated muscle contraction, actin filament organization and ATP biosynthetic process. Here, we reported that ALDOA is a highly expressed in lung squamous cell carcinoma (LSCC) and its expression level is correlated with LSCC metastasis, grades, differentiation status and poor prognosis. Depletion of ALDOA expression in the lung squamous carcinoma NCI-H520 cells reduces the capabilities of cell motility and tumorigenesis. These data suggest that ALDOA could be a potential marker for LSCC metastasis and a therapeutic target for drug development.
Successful sexual reproduction in animals and plants requires communication between male and female gametes. In flowering plants, unlike in animals, eggs and sperm cells are enclosed in multicellular embryo sacs and pollen grains, respectively; guided growth of the pollen tube into the ovule is necessary for fertilization. Pollen tube guidance requires accurate perception of ovule-emitted guidance cues by the receptors in pollen tubes. Although several ovule-secreted peptides controlling pollen tube guidance have recently been identified, i.e., maize EGG APPARATUS1 (EA1), Torenia LURE1/LURE2, and Arabidopsis CRP810_1/AtLURE1, little is known about the receptors. Here, we identified two receptor-like kinase (RLK) genes preferentially expressed in Arabidopsis pollen tubes, Lost In Pollen tube guidance 1 (LIP1) and 2 (LIP2), which are involved in guidance control of pollen tubes. LIP1 and LIP2 were anchored to the membrane in the pollen tube tip region via palmitoylation, which was essential for their guidance control. Simultaneous inactivation of LIP1 and LIP2 led to impaired pollen tube guidance into micropyle and significantly reduced attraction of pollen tubes toward AtLURE1. Our results suggest that LIP1 and LIP2 represent essential components of the pollen tube receptor complex to perceive the female signal AtLURE1 for micropylar pollen tube guidance.
In flowering plants, extensive male–female interactions are required for successful fertilization in which various signaling cascades are involved. Prevacuolar compartments (PVC) and vacuoles are two types of subcellular compartments that terminate signal transduction by sequestrating signaling molecules in yeast and mammalian cells; however, the manner in which they might be involved in male–female interactions in plants is unknown. In this study, we identified Arabidopsisthaliana vacuolar protein sorting 41 (AtVPS41), encoded by a single-copy gene with sequence similarity to yeast Vps41p, as a new factor controlling pollen tube–stigma interaction. Loss of AtVPS41 function disrupted penetration of pollen tubes into the transmitting tissue and thus led to failed male transmission. In the pollen tubes, AtVPS41 protein is associated with PVCs and the tonoplast. We demonstrate that AtVPS41 is required for the late stage of the endocytic pathway (i.e., endomembrane trafficking from PVCs to vacuoles) because internalization of cell-surface molecules was normal in the vps41-deficient pollen tubes, whereas PVC-to-vacuole trafficking was impaired. We further show that the CHCR domain is required for subcellular localization and biological functioning of AtVPS41. These results indicate that the AtVPS41-mediated late stage of the endocytic pathway is essential for pollen tube–stigma interaction in Arabidopsis.
Clear cell renal cell carcinoma (ccRCC) is the most aggressive RCC subtype with high metastasis, chemotherapy and radiotherapy resistance, and poor prognosis. This study attempted to establish the deregulations of miR-4521 and FAM129A together with their correlation to and mechanism of regulation of ccRCC development and progression. FAM129A acted as tumor promotor and miR-4521 acted as a suppressor in ccRCC. As measured in surgical tumorous tissues from ccRCC patients, FAM129A overexpression and miR-4521 deficiency together contributed to ccRCC progression by promoting advances in patients’ TNM stage and Fuhrman grade. Both the FAM129A knockdown and miR-4521 overexpression could reduce the in vitro migration and invasion abilities of renal cancer cells 786-O and ACHN, through the TIMP-1/MMP2/MMP9 pathway and could decrease their proliferation by promoting their apoptosis through the MDM2/p53/Bcl2/Bax pathway. By directly targeting the 3′-UTR domain of FAM129A , miR-4521 was negatively correlated with FAM129A /FAM129A levels in ccRCC progression and renal cancer cell malignancies. This work establishes the miR-4521-FAM129A axial regulation mechanism in ccRCC. Micro-4521 deficiency leads to FAM129A /FAM129A upregulation, which synergistically enhances the migration and invasion of renal cancer cells due to the induced decrease of TIMP-1 and increases of MMP2 and MMP9, and increases their growth through escaping apoptosis by suppressing p53 by way of upregulation of induced MDM2. The current work provides new clues to assist fundamental research into the diagnosis and treatment of ccRCC.
Background: Tumor metastasis is one of the main causes of the high mortality of hepatocellular carcinoma (HCC). E-Twenty Six variant gene 6 (ETV6) is a strong transcriptional repressor, associated with the development and progression of tumors. However, the exact role and underlying mechanism of ETV6 in HCC remain unclear. Methods: Western blotting, quantitative real-time PCR and immunohistochemistry were used to detect the expression levels of ETV6, CRKL (v-crk sarcoma virus CT10 oncogene homologue (avian)-like) and miR-429 in HCC tissues and cells; Transwell chamber and F-actin cytoskeleton staining assay to examine the effects of ETV6 and CRKL deregulation on the migration, invasion and cytoskeleton of HCC cells; Co-immunoprecipitation assay to determine the interaction between CRKL and ETV6; Chromatin immunoprecipitation assay to investigate the interaction between ETV6 and miR-429. Results: We established a novel ETV6-miR-429-CRKL regulatory circuitry contributes to HCC metastasis. ETV6 and CRKL were frequently increased, while miR-429 was downregulated in both hepatocarcinoma tissues and hepatocarcinoma cells. Moreover, ETV6 upregulation was positively correlated with CRKL upregulation, and two negative correlations were also established for ETV6 and CRKL upregulation with miR-429 downregulation in both hepatocarcinoma patients' tumorous tissues and hepatocarcinoma cells. Functional investigations revealed that overexpression and knockdown of ETV6 was remarkably effective in promoting and suppressing HCC cell migration, invasion, cytoskeleton F-actin expression and arrangement, whereas, CRKL overexpression exhibited similar effects to the overexpression of ETV6. Mechanistically, ETV6 negatively regulates miR-429 expression by directly binding to the promoter region of miR-429; miR-429 negatively regulates CRKL expression by selectively targeting CRKL-3′-UTR; ETV6 directly binds to CRKL and positively regulates its expression, which in turn CRKL positively regulates ETV6 expression.
In the mouse, the osteoblast-derived hormone Lipocalin-2 (LCN2) suppresses food intake and acts as a satiety signal. We show here that meal challenges increase serum LCN2 levels in persons with normal or overweight, but not in individuals with obesity. Postprandial LCN2 serum levels correlate inversely with hunger sensation in challenged subjects. We further show through brain PET scans of monkeys injected with radiolabeled recombinant human LCN2 (rh-LCN2) and autoradiography in baboon, macaque, and human brain sections, that LCN2 crosses the blood-brain barrier and localizes to the hypothalamus in primates. In addition, daily treatment of lean monkeys with rh-LCN2 decreases food intake by 21%, without overt side effects. These studies demonstrate the biology of LCN2 as a satiety factor and indicator and anorexigenic signal in primates. Failure to stimulate postprandial LCN2 in individuals with obesity may contribute to metabolic dysregulation, suggesting that LCN2 may be a novel target for obesity treatment.
Background Hip fractures are associated with a high rate of morbidity and mortality, and successful ambulation after surgery is an important outcome in this patient population. Objective This study aims to determine whether 25-hydroxyvitamin D [25(OH)D] concentration or the Geriatric Nutritional Risk Index (GNRI) is associated with mortality or rates of walking in a patient cohort after hip fracture surgery. Methods Patients undergoing hip fracture repair from a multisite study in North America were included. Mortality and mobility were assessed at 30 and 60 d after surgery. Serum albumin, 25(OH)D, and intact parathyroid hormone were measured. Patients were characterized according to 25(OH)D <12 ng/mL, 12 to <20 ng/mL, 20 to <30 ng/mL, or ≥30 ng/mL. GNRI was categorized into major/moderate nutritional risk (<92), some risk (92 to <98), or in good nutritional status (≥98). Results Of the 290 patients [aged 82 ± 7 y, BMI (kg/m2): 25 ± 5], 73% were women. Compared with patients with <12 ng/mL, those with higher 25(OH)D concentrations had higher rates of walking at 30 d (P = 0.031): 12 to <20 ng/mL (adjusted OR: 2.61; 95% CI: 1.13, 5.99); 20 to <30 ng/mL (3.48; 1.53, 7.95); ≥30 ng/mL (2.84; 1.12, 7.20). In addition, there was also greater mobility at 60 d (P = 0.028) in patients with higher 25(OH)D compared with the reference group (<12 ng/mL). Poor nutritional status (GNRI <92) showed an overall trend to reduce mobility (unadjusted P = 0.044 and adjusted P = 0.056) at 30 but not at 60 d. There was no association of vitamin D or GNRI with mortality at either time. Conclusions Vitamin D deficiency (<12 ng/mL) is associated with reduced ambulation after hip fracture surgery, whereas GNRI also contributes to immobility but is a less reliable predictor. Mechanisms that can explain why vitamin D deficiency is associated with mobility should be addressed in future studies.
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