MicroRNA Expression Patterns in Human Astrocytes in Relation to Anatomical Location and Age

Abstract

Anatomic distribution and age are variables linked to functions of astrocytes under physiologic and pathologic conditions. We measured the relative expression of a panel of microRNAs (miRNAs) in astrocytes captured by laser micro-dissection from normal human adult white and grey matter, human fetal white matter and germinal matrix samples. Although expression of most miRNAs was comparable between adult and fetal samples, regional differences were observed. In the adult cerebral cortex, expression of miRNAs in morphologically distinct inter-laminar astrocytes underlying the glial limitans differed from those in deeper cortical layers, suggesting functional specialization possibly related to structural stability and defense from potentially harmful factors in the cerebrospinal fluid. Differences between adult white and grey matter miRNA expression included higher expression of pro-inflammatory miRNAs in the former, potentially contributing to differences in inflammation between grey and white matter plaques in multiple sclerosis. Lower expression of miRNAs in fetal versus adult white matter astrocytes likely reflects the immaturity of these migrating cells. Highly expressed miRNAs in the fetal germinal matrix are probably relevant in development and also recapitulate some responses to injury. Future studies can address regional alterations of miRNA expression in pathological conditions.

Chronic inflammation in multiple sclerosis — seeing what was always there

“…Experiments with a rodent model have provided novel evidence for a long-lasting, epigenetically mediated microglial memory of recurrent systemic inflammation 78 . Interactions between microglia and astrocytes might contribute to this phenomenon, as functional changes in astrocytes relevant to their roles in innate immune responses are regulated by miRNA changes with ageing 79 . One goal in the use of advanced imaging in MS is to monitor not just the extent of chronic brain immune activation and the associated cellular phenotypes, but also the trafficking of inflammatory cells from the blood into the CNS that contribute to modulation of this immune activation.…”

Exosomal MicroRNAs Released by Activated Astrocytes as Potential Neuroinflammatory Biomarkers

“…Few studies have reported miRNA transcriptome analysis of astrocytes from adult and human fetal brains. These studies have identified a subset of astrocyte-specific miRNAs under the normal physiological resting stage as well as IL-1β induced neuroinflammatory stress [12,13]. In this study, our goal was to identify exosomal miRNAs secreted by human astrocytes under proinflammatory and oxidative stress conditions and compare them to exosomal miRNAs released from resting astrocytes.…”

MicroRNA‐31 is required for astrocyte specification

“…However, few studies have addressed the role of non-coding factors, such as miRs, and their potential contribution towards astrocytogenesis (Cacci et al 2017; Jovicic and Gitler 2017; Karthikeyan et al 2016; Li et al 2016; Rao et al 2016; Smith et al 2010; Yun et al 2010). By comparison, more is known about the contributions of miRs during neurogenesis (Boutz et al 2007; Choi et al 2008; Hobert 2006; Johnston et al 2005; Kuss and Chen 2008; Makeyev et al 2007; Sempere et al 2004).…”