MicroRNA Profiling Shows a Time-Dependent Regulation within the First 2 Months Post-Birth and after Mild Neonatal Hypoxia in the Hippocampus from Mice

Abstract

Brain development occurs until adulthood, with time-sensitive processes happening during embryo development, childhood, and puberty. During early life and childhood, dynamic changes in the brain are critical for physiological brain maturation, and these changes are tightly regulated by the expression of specific regulatory genetic elements. Early life insults, such as hypoxia, can alter the course of brain maturation, resulting in lifelong neurodevelopmental conditions. MicroRNAs are small non-coding RNAs, which regulate and coordinate gene expression. It is estimated that one single microRNA can regulate the expression of hundreds of protein-coding genes.. Uncovering the miRNome and microRNA-regulated transcriptomes may help to understand the patterns of genes regulating brain maturation, and their contribution to neurodevelopmental pathologies following hypoxia at Postnatal day 7. Here, using a PCR-based platform, we analyzed the microRNA profile postnatally in the hippocampus of control mice at postnatal day 8, 14, and 42 and after hypoxia at postnatal day 7, to elucidate the set of microRNAs which may be key for postnatal hippocampus maturation. We observed that microRNAs can be divided in four groups based on their temporal expression. Further after an early life insult, hypoxia at P7, 15 microRNAs showed a misregulation over time, including Let7a. We speculated that the transcriptional regulator c-myc is a contributor to this process. In conclusion, here, we observed that microRNAs are regulated postnatally in the hippocampus and alteration of their expression after hypoxia at birth may be regulated by the transcriptional regulator c-myc.

Expression Profiling of Adipogenic and Anti-Adipogenic MicroRNA Sequences following Methylmercury Exposure in Caenorhabditis elegans

“…Sun et al have found that the expression of mmu-miR-15a-5p, mmu-miR-125b-5p, and mmu-miR-132-5p fluctuated in expression following ischemic transient common carotid artery occlusion in Mongolian gerbils (Meriones unguiculatus), leading to altered expression of target genes TDP43, FUS/TLS, and Hsp70 in the hippocampus [61]. Similar fluctuations in miRNA expression were found after 2 months post birth in mouse hippocampus following neonatal hypoxia [62]. Time-dependent changes in miRNA levels have also been observed for tumorigenesis, infection, and adipogenesis [63][64][65].…”

miRNAs: From Master Regulators of Gene Expression to Biomarkers Involved in Intercellular Communication

“…In this Special Issue, some papers show how miRNAs can affect the development and function in different organs and systems. For instance, Leavy et al [24] reported that the impairment of normal brain maturation caused by early life brain injury (such as hypoxia) is accompanied by modification of miRNA expression, possibly driven by cMYC. In their review, Piquer-Gil et al [25] focused on the importance of the balance between two key pathways (Wnt/β-catenin and Hippo pathways) in the progression of the pathological arrhythmogenic cardiomyopathy (ACM) phenotype, a form of heart disease that can cause sudden death.…”