Microglia is considered the central nervous system (CNS) resident macrophages that establish an innate immune response against pathogens and toxins. However, the recent studies have shown that ...microglial gene and protein expression follows a circadian pattern; several immune activation markers and clock genes are expressed rhythmically without the need for an immune stimulus. Furthermore, microglia responds to an immune challenge with different magnitudes depending on the time of the day. This review examines the circadian control of microglia function and the possible physiological implications. For example, we discuss that synaptic prune is performed in the cortex at a certain moment of the day. We also consider the implications of daily microglial function for maintaining biological rhythms like general activity, body temperature, and food intake. We conclude that the developmental stage, brain region, and pathological state are not the only factors to consider for the evaluation of microglial functions; instead, emerging evidence indicates that circadian time as an essential aspect for a better understanding of the role of microglia in CNS physiology.
Main Points
Microglia are rhythmic cells with an oscillatory expression in clock genes, cytokines, and other microglial markers.
Microglial circadian rhythms determine their physiological function and immune responses.
Sleep has a major role in learning, memory consolidation, and metabolic function. Although it is known that sleep restriction increases the accumulation of amyloid β peptide (Aβ) and the risk to ...develop Alzheimer’s disease (AD), the mechanism behind these effects remains unknown. In this review, we discuss how chronic sleep restriction induces metabolic and cognitive impairments that could result in the development of AD in late life. Here, we integrate evidence regarding mechanisms whereby metabolic signaling becomes disturbed after short or chronic sleep restriction in the context of cognitive impairment, particularly in the accumulation of Aβ in the brain. We also discuss the role of the blood-brain barrier in sleep restriction with an emphasis on the transport of metabolic signals into the brain and Aβ clearance. This review presents the unexplored possibility that the alteration of peripheral metabolic signals induced by sleep restriction, especially insulin resistance, is responsible for cognitive deficit and, subsequently, implicated in AD development.
BORIS is a transcription factor aberrantly expressed in human cancers that can regulate the expression of estrogen receptors in endometrial cancer and breast cancer. We evaluated the expression of ...BORIS and the estrogen receptors alpha (ER-α) and beta (ER-β) in ten cell lines derived from cervical cancer using RT-PCR and Western-blot. We also evaluated 54 cervical tissues: normal epithelia, low-grade intraepithelial lesions (LSIL), high-grade intraepithelial lesions (HSIL), and invasive squamous carcinomas (SC) using immunohistochemistry. In the cell lines, BORIS mRNA and protein expressions are associated with ER-β expression but not with ER-α expression. In the normal cervical epithelium, ER-α and ER-β were expressed but the BORIS protein was not detected. In the LSIL samples, BORIS, ER-α and ER-β were expressed; however, in the HSIL samples, only the BORIS and ER-β expressions were detected, but ER-α expression was minimal or null. In the SC, only BORIS and ER-β were detected. In summary, the results show that the expressions of BORIS and ER-β increase while the expression of ER-α decreases according to the severity of the lesions. These results suggest synergistic roles for BORIS and ER-β during cervical cancer progression with a possible regulation of the estrogen receptors by BORIS in the development of cervical cancer; however, more detailed studies are needed to confirm this suggestion and to determine the precise role of BORIS in cervical cancer.
The main purpose of our work was to elucidate factors responsible for the geographical differences in leaf-litter decomposition rates in Spanish oligotrophic headwater streams. Decomposition ...experiments with alder (Alnus glutinosa) leaf litter were carried out in 22 headwater streams in 4 different climatic regions across the Iberian Peninsula (Cornisa Cantábrica, Cordillera Litoral Catalana, Sierra de Guadarrama, and Sierra Nevada). Streams that were similar in size, flowed mainly over siliceous substrate in catchments with scarce human settlements and activities, and fell within a range of low nutrient concentrations were chosen in each region. Breakdown rates were regionally variable and were low (0.109–0.198% ash-free dry mass AFDM/degree day dd) in the Cornisa Cantábrica, the most mesic and Atlantic region, and high (0.302–0.639% AFDM/dd) in Sierra de Guadarrama, one of the coldest and most inland areas. Temperature was not the determining factor affecting differences in breakdown rates among regions, and breakdown rates were not related to concentrations of dissolved nutrients. However, microbial reproductive activity (sporulation rates) was significantly correlated with dissolved P concentration. Breakdown rates were explained better by presence and feeding activities of detritivores than by decomposer activity. Incorporation of breakdown rates in assessment schemes of stream ecological status will be difficult because leaf processing does not respond unequivocally to environmental factors when climatic regions are considered. Thus, regional adjustments of baseline standards in reference conditions will be required.
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