miR-219a-5p Regulates Rorß During Osteoblast Differentiation and in Age-related Bone Loss.

Developing novel approaches to treat skeletal disorders requires an understanding of how critical molecular factors regulate osteoblast differentiation and bone remodeling. We have reported that (1) retinoic acid receptor-related orphan receptor beta (Rorß) is upregulated in bone samples isolated from aged mice and humans in vivo; (2) Rorß expression is inhibited during osteoblastic differentiation in vitro; and (3) genetic deletion of Rorß in mice results in preservation of bone mass during aging. These data establish that Rorß inhibits osteogenesis and that strict control of Rorß expression is essential for bone homeostasis. Because microRNAs (miRNAs) are known to play important roles in the regulation of gene expression in bone, we explored whether a predicted subset of nine miRNAs regulates Rorß expression during both osteoblast differentiation and aging. Mouse osteoblastic cells were differentiated in vitro and assayed for Rorß and miRNA expression. As Rorß levels declined with differentiation, the expression of many of these miRNAs, including miR-219a-5p, was increased. We further demonstrated that miR-219a-5p was decreased in bone samples from old (24-month) mice, as compared with young (6-month) mice, concomitant with increased Rorß expression. Importantly, we also found that miR-219a-5p expression was decreased in aged human bone biopsies compared with young controls, demonstrating that this phenomenon also occurs in aging bone in humans. Inhibition of miR-219a-5p in mouse calvarial osteoblasts led to increased Rorß expression and decreased alkaline phosphatase expression and activity, whereas a miR-219a-5p mimic decreased Rorß expression and increased osteogenic activity. Finally, we demonstrated that miR-219a-5p physically interacts with Rorß mRNA in osteoblasts, defining Rorß as a true molecular target of miR-219a-5p. Overall, our findings demonstrate that miR-219a-5p is involved in the regulation of Rorß in both mouse and human bone. © 2018 American Society for Bone and Mineral Research.

Prenatal ethanol exposure disrupts intraneocortical circuitry, cortical gene expression, and behavior in a mouse model of FASD.

In utero ethanol exposure from a mother's consumption of alcoholic beverages impacts brain and cognitive development, creating a range of deficits in the child (Levitt, 1998; Lebel et al., 2012). Children diagnosed with fetal alcohol spectrum disorders (FASD) are often born with facial dysmorphology and may exhibit cognitive, behavioral, and motor deficits from ethanol-related neurobiological damage in early development. Prenatal ethanol exposure (PrEE) is the number one cause of preventable mental and intellectual dysfunction globally, therefore the neurobiological underpinnings warrant systematic research. We document novel anatomical and gene expression abnormalities in the neocortex of newborn mice exposed to ethanol in utero. This is the first study to demonstrate large-scale changes in intraneocortical connections and disruption of normal patterns of neocortical gene expression in any prenatal ethanol exposure animal model. Neuroanatomical defects and abnormal neocortical RZRß, Id2, and Cadherin8 expression patterns are observed in PrEE newborns, and abnormal behavior is present in 20-d-old PrEE mice. The vast network of neocortical connections is responsible for high-level sensory and motor processing as well as complex cognitive thought and behavior in humans. Disruptions to this network from PrEE-related changes in gene expression may underlie some of the cognitive-behavioral phenotypes observed in children with FASD.

Altered layer-specific gene expression in cortical samples from patients with temporal lobe epilepsy.

PURPOSE: Neuropathologic investigations frequently reveal the presence of architectural cortical dysplasia in patients with temporal lobe epilepsy (TLE), sometimes as an isolated finding but more commonly associated with hippocampal sclerosis (HS) and white matter abnormalities. The histologic pattern and the developmental origin of these alterations are not clear, and their diagnostic criteria are poorly defined. The aim of this study was to investigate the expression patterns of layer-specific genes in cortical specimens from patients with TLE presenting different subtypes of cortical malformations in order to elucidate the disorganization of the laminar architecture of such epileptogenic abnormalities and provide evidence to enable a more objective neuropathologic diagnosis. METHODS: We analyzed the expression patterns of CUX2, RORBETA, ER81, NURR1, and CTGF genes, respectively specific markers of layers II-III, IV, V, VI, and VIb, in surgical samples by means of in situ hybridization and compared them with those observed in control cortices. The pathologic samples included typical architectural dysplasia (group 1); temporal lobe sclerosis, a variant of architectural dysplasia (group 2); and white matter heterotopic neuronal aggregates, namely small lentiform nodules (group 3). These abnormalities may have been associated or not with HS. KEY FINDINGS: All of the genes had a laminar expression pattern in normal cortices, whereas groups 1 and 2 showed alterations mainly involving layers V and VI, and highlighted by the altered distribution of ER81- and NURR1-positive cells. The expression of ER81 and NURR1 genes was different among the groups, and atypical coexpression of NURR1 and CUX2 mRNA was detected in the neurons making up the small lentiform nodules. SIGNIFICANCE: These findings indicate that defects in cortical organization involving the deeper cortical neurons may be a common etiopathogenic mechanism in group 1 and 2 cortical dysplasia, whether isolated or associated with HS, and that developmental disorders may also be present in the white matter (group 3). They also provide evidence that the layer-specific genes can be usefully used to investigate the neuropathology of human cortical dysplasia.