Hirschsprung disease (HSCR) is a congenital disorder caused by the defective function of the embryonic enteric neural crest. The impaired migration of embryonic enteric neural crest plays an important role in the pathogenesis of this disease. Recent studies showed that the ARP2/3 complex and RAC isoforms had effects on actin cytoskeleton remodelling, which contributes to migration. Moreover, some regulatory relationships were identified between ARP2/3 complex and RAC isoforms. Although microRNAs (miRNAs) have been known to modulate target gene expression on the post‐transcriptional level, little is known about the regulation among miRNAs, ARP2/3 complex and RAC isoforms. Here, we report that down‐regulation of ARP2 and ARP3, two main subunits of ARP2/3 complex, suppressed migration and proliferation in 293T and SH‐SY5Y cell lines via the inhibition of RAC1 and RAC2. Meanwhile, as the target genes, ARP2 and ARP3 are reduced by increased miR‐24‐1* and let‐7a*, respectively, in 70 HSCR samples as compared with 74 normal controls. Co‐immunoprecipitation showed that aberrant reduction in ARP2 and ARP3 could weaken the function of ARP2/3 complex. Our study demonstrates that the miR‐24‐1*/let‐7a*‐ARP2/3 complex‐RAC isoforms pathway may represent a novel pathogenic mechanism for HSCR.

Hirschsprung's disease (HSCR) is a congenital disorder characterized by the absence of enteric neural crest cells (ENCCs). LncRNA rhabdomyosarcoma 2-associated transcript (RMST) is essential for the growth and development of neuron. This study aimed to reveal the role of RMST in the pathogenesis of HSCR. The expression level of RMST, miR-1251, SOX2, and AHNAK was evaluated with qRT-PCR or western blot. CCK-8 and transwell assays were applied to detect cell proliferation and migration. CHIP and RIP assays were applied to determine the combination relationship between SOX2 and promoter region of miR-1251 or RMST and SOX2, respectively. Dual-luciferase reporter assay was performed to confirm miR-1251 targeted AHNAK. As results have shown, RMST was downregulated in the aganglionic colon of HSCR patients. The knockdown of RMST attenuated cell proliferation and migration significantly. MiR-1251, the intronic miRNA of RMST, was also low expressed in HSCR, but RMST did not alter the expression of miR-1251 directly. Furthermore, SOX2 was found to regulate the expression of miR-1251 via binding to the promoter region of miR-1251, and RMST strengthened this function by interacting with SOX2. Moreover, AHNAK was the target gene of miR-1251, which was co-regulated by RMST and SOX2. In conclusion, our study demonstrated that RMST functioned as a transcriptional co-regulator of SOX2 to regulate miR-1251 and resulted in the upregulation of AHNAK, leading to the occurrence of HSCR. The novel RMST/SOX2/miR-1251/AHNAK axis provided potential targets for the diagnosis and treatment of HSCR during embryonic stage.

Hirschsprung’s disease (HSCR) is a congenital malformation of the enteric nervous system (ENS) caused by deficient enteric neural crest cell (ENCC) colonization. However, the mechanisms inducing impaired ENCC colonization remain unclear. This study investigates the involvement of extracellular vesicles (EVs), pivotal mediators of intercellular communication, in ENS development and HSCR pathogenesis. We find that treatment with plasma-derived EVs from children with HSCR (HSCR-EV) significantly inhibits ENCC proliferation and migration. MIR22HG is identified as the key mediator of the HSCR-EV-induced suppression of ENCC proliferation and migration. Schwann cells within the aganglionic colon of HSCR children derive EVs containing upregulated MIR22HG. In vitro, Schwann cell-derived EV-MIR22HG inhibits ENCC proliferation and migration. In vivo, it blocks ENCC colonization in the distal colon and disrupts ENS formation. MPP3 is identified as a potential downstream target of MIR22HG, with MIR22HG downregulating its expression via the m⁶A-dependent ALKBH5/IGF2BP3 axis. Collectively, Schwann cell-derived EVs transfer MIR22HG to ENCCs, downregulating MPP3 through the m⁶A/ALKBH5/IGF2BP3 pathway, and thereby disrupting ENCC colonization and impairing ENS formation.

BackgroundHirschsprung’s disease (HSCR) is a congenital colon disease characterized by the lack of ganglion cells which is closely related to impaired migration and proliferation of enteric neural crest cells (ENCCs). Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been authenticated as an important class of regulators of biological functions. In this study, a microarray analysis was conducted and found that Rhabdomyosarcoma 2-associated transcript (RMST), a newly defined lncRNA, was down-regulated in the stenotic segment of HSCR patients. MiR-1251 is transcribed from the intron region of RMST and was also low expressed in the aganglionic tract. This study aimed to clarify the roles they played in the occurrence of HSCR. MethodsQRT-PCR was applied to validate the mRNA expression of RMST, miR-1251, SOX2 and AHNAK, while western blotting was employed to evaluate the protein level of SOX2 and AHNAK in clinical samples and cells. CCK-8 and transwell assays were used to detect cell proliferation and migration after transfection. Chromatin immunoprecipitation (CHIP) was applied to confirm SOX2 could bind to the promoter region of miR-1251. RNA binding protein immunoprecipitation (RIP) was used to demonstrate the interaction between RMST and SOX2. Dul-luciferase reporter assay was performed to confirm miR-1251 could interact with AHNAK. ResultsWhen the expression of RMST or miR-1251 was reduced, cell proliferation and migration was attenuated. However, RMST not to influence the expression of miR-1251 directly. Through bioinformatic analysis, transcription factor SOX2 was predicted to bind to the promoter region of miR-1251 which was confirmed by CHIP assay. We also demonstrated that RMST exerted as a co-regulator of SOX2 via RIP assay. AHNAK was predicted as the downstream gene of miR-1251 confirmed by the dual-luciferase reporter assay. Furtherly, rescue experiments showed RMST functioned as a transcription co-regulator of SOX2 to upregulate the expression of downstream gene AHNAK by strengthening the regulation of SOX2 on miR-1251 in HSCR.ConclusionsThese findings uncovered the role of RMST/SOX2/miR-1251/AHNAK pathway during the development of Hirschsprung's disease and presented potential therapeutic targets for HSCR.

Hirschsprung’s disease (HSCR) is a congenital disorder characterized by the absence of enteric neural crest cells (ENCCs). Non-coding RNAs including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been authenticated as important regulators of biological functions. We conducted a microarray analysis and found lncRNA Rhabdomyosarcoma 2-associated transcript (RMST) was down-regulated in the stenotic segment of HSCR patients. MiR-1251 is transcribed from the intron region of RMST and was also low-expressed. When the expression of RMST or miR-1251 was reduced, the cell proliferation and migration were attenuated. However, RMST didn’t affect the expression of miR-1251 directly found in this study. Through bioinformatic analysis, transcription factor SOX2 was predicted to bind to the promoter region of miR-1251 which was confirmed by CHIP assay. Herein, we demonstrated that RMST exerted as a co-regulator of SOX2 to regulate the expression of miR-1251. Furtherly, AHNAK was proved to be the target gene of miR-1251 in this study. Taken together, we revealed the role of RMST/SOX2/miR-1251/AHNAK pathway in the occurrence of Hirschsprung’s disease and provided a potential therapeutic target for this disease. SUMMARY STATEMENT: Hirschsprung disease (HSCR) is characterized by a deficit in enteric neurons, however, the underlying mechanism remains unclear. This study revealed the role of lnc-RMST during the occurrence of HSCR.