MicroRNA therapeutic targets in neonatal hypoxic-ischemic brain injury: a narrative review

Dynamic whole-transcriptome landscape of acute bilirubin encephalopathy in newborns

Hyperbilirubinemia in newborns may progress to acute bilirubin encephalopathy (ABE), posing short- and long-term health risks. Despite extensive research identifying numerous mRNAs, lncRNAs, circRNAs, and miRNAs associated with brain injury, their roles in neonatal bilirubin-induced brain injury remain elusive. This study employed whole-transcriptome sequencing to ascertain the differentially expressed (DE) RNA profiles in a newborn ABE rat model, followed by bioinformatic analysis. A time-series competing endogenous RNA (ceRNA) regulatory network was established, and the expression trends of 9 arbitrarily chosen RNAs were verified through quantitative real-time polymerase chain reaction(qRT-PCR). In comparison with the control group, we identified 595, 888, and 1448 DE mRNAs; 22, 37, and 37 DE miRNAs; 1945, 1869, and 1997 DE lncRNAs; and 31, 28, and 36 DE circRNAs at 6 h, 12 h, and 24 h, respectively. Predominantly, these DERNAs contribute to biological functions and pathways associated with inflammation, immunity, metabolism, cell death, and neurodevelopmental regulation. Moreover, we constructed ceRNA networks of DE lncRNA/circRNA-DE miRNA-DE mRNA based on time series. The qRT-PCR expression trends for the selected 9 RNAs were generally similar to the RNA-seq outcomes. This investigation uniquely delineated the temporal expression patterns of mRNA and non-coding RNA in ABE, establishing ceRNA networks and identifying potential molecular mechanisms underlying bilirubin-induced hippocampal damage. Nonetheless, further studies are warranted to corroborate these findings in humans.

LncRNA-mir3471-limd1 regulatory network plays critical roles in HIBD

The purpose of this study was to identify the target genes of tcon_00044595, elucidate its activation site, and provide novel insights into the pathogenesis and treatment of neonatal hypoxic-ischemic brain damage (HIBD). Through homologous blast analysis, we identified predicted target sequences in the neighboring regions of the long non-coding RNA (lncRNA) tcon_00044595, suggesting that limd1 is its target gene. Starbase was utilized to identify potential candidate microRNAs associated with the lncRNA. The interaction between the candidate microRNAs and limd1 was investigated and validated using various experimental methods including in vitro cell culture, cell transfection, dual fluorescence reporter detection system, and real-time PCR. Homology alignment analysis revealed that the lncRNA tcon_00044595 exhibited a 246 bp homologous sequence at the 3' end of the adjacent limd1 gene, with a conservation rate of 68%. Analysis conducted on Starbase online identified three potential microRNA candidates: miR-3471, miR-883a-5p, and miR-214-3p. Intracellular expression of the limd1 gene was significantly down-regulated upon transfection with miR-3471, while the other two microRNAs did not produce noticeable effects. Luciferase reporter assays identified two interaction sites (UTR-1, UTR-2) between miR-3471 and the limd1 3'UTR, with UTR-1 exhibiting a strong influence. Further CCK8 assay indicated a protective role of miR-3471 during low oxygen stroke in HIBD. The potential regulatory relationship between lncRNA (tcon_00044595), miR-3471, and the target gene limd1 suggests their involvement in the occurrence and development of HIBD, providing new insights for investigating the underlying mechanisms and exploring targeted therapeutic approaches for HIBD.

TMEM175 downregulation participates in impairment of the autophagy related lysosomal dynamics following neonatal hypoxic-ischemic brain injury

The mechanism underlying long-term cognitive impairment caused by neonatal hypoxic-ischemic brain injury (HIBI) remains unclear. Autophagy is a closely related mechanism and may play a role in this process. We aimed to investigate the role of lysosomal transmembrane protein 175 (TMEM175) in the autophagy-lysosome pathway in neonatal rats with HIBI. A neonatal rat model of HIBI was established, hypoxia was induced, followed by left common carotid artery ligation. Expression levels of TMEM175 and the corresponding proteins involved in autophagy flux and the endolysosomal system fusion process were measured. Rats were administered TMEM175 plasmid via intracerebroventricular injection to induce overexpression. Brain damage and cognitive function were then assessed. TMEM175 was downregulated in the hippocampal tissue, and the autophagy-lysosome pathway was impaired following HIBI in neonatal rats. Overexpression of TMEM175 significantly mitigated neuronal injury and improved long-term cognitive and memory function in neonatal rats with HIBI. We found that improvement in the autophagy-lysosome pathway and endolysosomal system homeostasis, which are TMEM175 related, occurred via regulation of lysosomal membrane dynamic fusion. TMEM175 plays a critical role in maintaining the autophagy-lysosome pathway and endolysosomal homeostasis, contributing to the amelioration of neuronal injury and impaired long-term cognitive function following neonatal HIBI.