bims-ciryme Biomed News
on Circadian rhythms and metabolism
Issue of 2019‒05‒19
two papers selected by
Gabriela Da Silva Xavier
University of Birmingham

  1. Endocrinology. 2019 Jun 01. 160(6): 1411-1420
      Research over recent decades has established neuropeptide Y (NPY) neurons in the arcuate nucleus (Arc) of the hypothalamus as a group of powerful orexigenic acting neurons in the brain. However, genetic mouse models in combination with novel neuron-controlling chemogenetic and optogenetic technologies have also uncovered additional functions for this Arc NPY population that go beyond the simple food intake stimulatory action and link these NPY neurons to the control of energy expenditure, thermogenesis, physical activity, food-seeking behavior, and anxiety. This control is achieved by complex neuronal networks connecting these Arc NPY neurons with other vital neuronal centers in the brain, including the paraventricular nucleus, ventral tegmental area, amygdala, and brainstem. In addition, single-cell sequencing approaches have revealed that a greater heterogeneity of NPY neurons actually exists, giving rise to various subsets of NPY neuronal populations that are distinguished by the profile of other neurotransmitters that they coexpress. In this review we will focus on aspects of food intake-associated behaviors and shed more light on the integrative role of NPY neurons in potential interaction pathways of individual survival circuits.
  2. Curr Biol. 2019 Apr 30. pii: S0960-9822(19)30437-3. [Epub ahead of print]
      Sleep is fundamental to animal survival but is a vulnerable state that also limits how much time can be devoted to critical wake-dependent activities [1]. Although many animals are day-active and sleep at night, they exhibit a midday nap, or "siesta," that can vary in intensity and is usually more prominent on warm days. In humans, the balance between maintaining the wake state or sleeping during the day has important health implications [2], but the mechanisms underlying this dynamic regulation are poorly understood. Using the well-established Drosophila melanogaster animal model to study sleep [3], we identify a new wake-sleep regulator that we term daywake (dyw). dyw encodes a juvenile hormone-binding protein [4] that functions in neurons as a day-specific anti-siesta gene, with little effect on sleep levels during the nighttime or in the absence of light. Remarkably, dyw expression is stimulated in trans via cold-enhanced splicing of the dmpi8 intron [5] from the reverse-oriented but slightly overlapping period (per) clock gene [6]. The functionally integrated dmpi8-dyw genetic unit operates as a "behavioral temperate acclimator" by increasingly counterbalancing siesta-promoting pathways as daily temperatures become cooler and carry reduced risks from daytime heat exposure. While daily patterns of when animals are awake and when they sleep are largely scheduled by the circadian timing system, dyw implicates a less recognized class of modulatory wake-sleep regulators that primarily function to enhance flexibility in wake-sleep preference, a behavioral plasticity that is commonly observed in animals during the midday, raising the possibility of shared mechanisms.
    Keywords:  0.9 gene; Daywake; Drosophila; dmpi8 intron; juvenile hormone-binding protein; midday siesta; period clock gene; pre-mRNA splicing; sleep-wake behavior