Involvement of proliferative and apoptotic factors in the development of hindgut in rat fetuses with ethylenethiourea-induced anorectal malformations

Rack1-mediated ferroptosis affects hindgut development in rats with anorectal malformations: Spatial transcriptome insights

Anorectal malformation (ARM), a common congenital anomaly of the digestive tract, is a result of insufficient elongation of the urorectal septum. The cytoplasmic protein Receptor of Activated C-Kinase 1 (Rack1) is involved in embryonic neural development; however, its role in embryonic digestive tract development and ARM formation is unexplored. Our study explored the hindgut development and cell death mechanisms in ARM-affected rats using spatial transcriptome analysis. We induced ARM in rats by administering ethylenethiourea via gavage on gestational day (GD) 10. On GDs 14-16, embryos from both normal and ARM groups underwent spatial transcriptome sequencing, which identified key genes and signalling pathways. Rack1 exhibited significant interactions among differentially expressed genes on GDs 15 and 16. Reduced Rack1 expression in the ARM-affected hindgut, verified by Rack1 silencing in intestinal epithelial cells, led to increased P38 phosphorylation and activation of the MAPK signalling pathway. The suppression of this pathway downregulated Nqo1 and Gpx4 expression, resulting in elevated intracellular levels of ferrous ions, reactive oxygen species (ROS) and lipid peroxides. Downregulation of Gpx4 expression in the ARM hindgut, coupled with Rack1 co-localisation and consistent mitochondrial morphology, indicated ferroptosis. In summary, Rack1, acting as a hub gene, modulates ferrous ions, lipid peroxides, and ROS via the P38-MAPK/Nqo1/Gpx4 axis. This modulation induces ferroptosis in intestinal epithelial cells, potentially influencing hindgut development during ARM onset.

CircJag1 promotes apoptosis of ethylene thiourea-exposed anorectal malformations through sponging miR-137-3p by regulating Sox9 and suppressing Wnt/β-catenin pathway during the hindgut development of rat embryos

Anorectal malformations (ARMs) are common birth defects involving congenital structural anomalies of the gastrointestinal tract. As an important component of non-coding RNAs, circular RNAs (circRNAs) widely participate in the digestive system development; however, the specific molecular mechanism of their involvement in ARM occurrence remains obscure. Herein, we generated rat models of ARMs induced by ethylene thiourea. A novel circRNA (circJag1) was screened and identified by RNA-Seq, which is remarkably upregulated in hindgut tissues of ARM rat embryos. In vivo experiments, colocation analysis via fluorescence in situ hybridization, and immunofluorescence further demonstrated that the disordered circJag1/miR-137-3p/Sox9 expression caused a spatiotemporal imbalance in the urorectal septum (URS) of ARMs. In vitro, functional assays confirmed that circJag1 upregulation resulted in the degradation of nuclear β-catenin, C-myc, and Cyclin D1 in rat intestinal epithelial cells, as well as the promotion of apoptosis and suppression of cell proliferation. Mechanistically, dual-luciferase reporter assay and RNA immunoprecipitation assay indicated that circJag1 acted as a miR-137-3p sponge, thereby inhibiting its repressive effect on its target Sox9. Further experiments showed that a loss of Sox9 abolished the circJag1-mediated increase in apoptosis. In conclusion, aberrantly high circJag1 expression promotes epithelial apoptosis by suppressing the canonical Wnt/β-catenin pathway via the miR-137-3p/Sox9 axis, which leads to fusion failure of the URS and cloacal membrane, and eventually contributed to ARMs. Our achievements might boost the comprehension of ARM pathogenesis and could provide a novel candidate target for the development of therapies for ARMs to complement surgical treatment.

Pelvic floor and perineal muscles: a dynamic coordination between skeletal and smooth muscles on pelvic floor stabilization

The purpose of this review is to present our researches on the pelvic outlet muscles, including the pelvic floor and perineal muscles, which are responsible for urinary function, defecation, sexual function, and core stability, and to discuss the insights into the mechanism of pelvic floor stabilization based on the findings. Our studies are conducted using a combination of macroscopic examination, immunohistological analysis, 3D reconstruction, and imaging. Unlike most previous reports, this article describes not only on skeletal muscle but also on smooth muscle structures in the pelvic floor and perineum to encourage new understanding. The skeletal muscles of the pelvic outlet are continuous, which means that they share muscle bundles. They form three muscle slings that pass anterior and posterior to the anal canal, thus serving as the foundation of pelvic floor support. The smooth muscle of the pelvic outlet, in addition to forming the walls of the viscera, also extends in three dimensions. This continuous smooth muscle occupies the central region of the pelvic floor and perineum, thus revising the conventional understanding of the perineal body. At the interface between the levator ani and pelvic viscera, smooth muscle forms characteristic structures that transfer the lifting power of the levator ani to the pelvic viscera. The findings suggest new concepts of pelvic floor stabilization mechanisms, such as dynamic coordination between skeletal and smooth muscles. These two types of muscles possibly coordinate the direction and force of muscle contraction with each other.

miR-141-3p affects β-catenin signaling and apoptosis by targeting Ubtd2 in rats with anorectal malformations

Anorectal malformations (ARMs) are the most common gastrointestinal malformations. miR-141-3p was obtained from whole-transcriptome sequencing, and Ub domain-containing protein 2 (Ubtd2) was predicted as the target gene. An ARM rat model was induced using ethylenethiourea. Fluorescence in situ hybridization and immunofluorescence were used to detect the spatiotemporal expression of miR-141-3p and Ubtd2, respectively. A dual-luciferase reporter assay confirmed their targeting relationship, and cell proliferation and apoptosis were investigated after transfection in the intestinal epithelium (IEC-6). Additionally, western blotting and co-immunoprecipitation were used to examine the protein levels and the endogenous binding relationship. miR-141-3p was downregulated in the ARM group, whereas Ubtd2 increased and colocalized with TUNEL-positive cells. After miR-141-3p inhibition, protein expression of USP5 and β-catenin was affected via Ubtd2, and USP5 could bind to both Ubtd2 and β-catenin. Flow cytometry analysis and caspase 3/7 staining demonstrated that downregulated miR-141-3p promoted cell apoptosis through Ubtd2. In summary, targeting Ubtd2 decreased in miR-141-3p and promoted apoptosis of intestinal epithelium and regulated β-catenin expression. This may cause aberrant apoptosis during hindgut development and mediate the imbalance of β-catenin signaling in the cloaca, further affecting the occurrence of ARMs.

Global Development of Research on Anorectal Malformations over the Last Five Decades: A Bibliometric Analysis

Purpose: Anorectal malformations (ARM) are one of the most challenging congenital malformations in pediatric surgery. We aimed to assess the research activity on ARM over the last five decades. Methods: Data on original research publications were retrieved from the Web of Science Core Collection (1970–2020), and analyzed for countries, authors, scientific journals, and top-ten papers. Scientific quantity was assessed by the number of publications. Research quality was estimated from the number of citations, average citation rate per item (ACI), and h-index. Results: A total number of 1595 articles with 19,419 citations (ACI = 12.2; h-index = 54) were identified. The annual number of publications and citations significantly increased over time (p < 0.0001). The USA (n = 386; 24.2%), Japan (n = 153; 9.6%), and China (n = 137; 8.6%) were the most productive countries; and the USA (n = 7850; ACI = 20.3; h-index = 44), Japan (n = 1937; ACI = 12.6; h-index = 21), and the Netherlands (n = 1318; ACI = 17.3; h-index = 22) were the top cited countries. Articles were preferentially published in JPS (n = 391; 24.5%), PSI (n = 181; 11.3%), and EJPS (n = 56; 3.5%). Top-ten cited papers focused on classification (n = 1), surgical technique (n = 3), associated syndromes (n = 2), postoperative outcome (n = 3), and basic research (n = 1). Conclusion: This bibliometric study provides valuable insights into the global development of ARM research, and shows that clinical studies and international collaborations dominate in this field.

Ameliorative Effects of Aspergillus awamori against the Initiation of Hepatocarcinogenesis Induced by Diethylnitrosamine in a Rat Model: Regulation of Cyp19 and p53 Gene Expression

Hepatocellular carcinoma (HCC) is the most common cancer in humans. Despite advances in its treatment, liver cancer remains one of the most difficult cancers to treat. This study aimed to investigate the ameliorative action and potential mechanism of Aspergillus awamori (ASP) administration against the initiation process of liver carcinogenesis induced by diethylnitrosamine (DEN) in male Wistar rats. Seventy-two male rats were divided equally into eight groups as follows, Group 1: untreated control; Group 2: DEN (200 mg/kg bw) intra-peritoneally for the initiation of HCC; Groups 3-5: DEN + ASP at a dose of 1, 0.5, and 0.25 mg/kg bw and groups 6-8: ASP at a dose of 1, 0.5, and 0.25 mg/kg bw. Supplementation of A. awamori significantly lightened the adverse impacts induced by DEN via restoring the leukogram to normal, lowering the elevated serum aspartate aminotransferase (AST), alanine transaminase (ALT), and γ-glutamyl transferase (GGT), and alkaline phosphatase (ALP). Furthermore, it enhanced the hepatic antioxidant capacity through increasing the reduced glutathione (GSH) level and catalase (CAT) activity with a marked reduction in malondialdehyde (MDA) level. In addition, it decreased the positive GST-P foci. Likewise, a significant alteration of DEN-associated hepatocarcinogenesis occurred through inhibiting cytochrome P450 (Cyp19) and activating p53 gene expression. In conclusion, supplementation of A. awamori counteracts the negative effects of DEN, inhibits the early development of GST-P-positive foci and could be used as a new alternative strategy for its chemo-preventive effect in liver cancer. To the best of our knowledge, the present study is the first to report the hepato-protective effect of A. awamori in induced hepatocarcinogenesis.

Upregulation of PPPDE1 contributes to anorectal malformations via the mitochondrial apoptosis pathway during hindgut development in rats

Congenital anorectal malformations (ARMs) are among the most prominent deformities of the gastrointestinal tract; however, their precise aetiology remains obscure. Immunohistochemistry demonstrated that, in the ARM group, the PPPDE1-positive cells were widely distributed in the hindgut epithelial tissue from GD13 to GD16. Immunofluorescence revealed that most TUNEL-, Bax-, and Cytochrome C (Cyt C)-positive cells overlapped with PPPDE1-positive cells in the urorectal septum (URS). Western blotting and quantitative real-time RT-PCR revealed that PPPDE1 levels were significantly higher in the ARM group from GD13 to GD14 (p < 0.05). IEC-6 cells were transfected with PPPDE1 overexpression plasmid/NC (negative control) or si-PPPDE1/si-NC. Flow cytometry analysis and CCK-8 assay (used to detect apoptosis and proliferation, respectively), as well as western blotting, showed that the levels of PPPDE1 were positively correlated with the pro-apoptotic molecules Bax and Cyt C. Accordingly, aberrantly high expression of PPPDE1 caused a spatiotemporal imbalance in foetal rats with ARMs during hindgut development. Therefore, the upregulation of PPPDE1 may promote epithelial apoptosis and reduce proliferation in the hindgut via the mitochondrial apoptotic pathway. This could affect the fusion of the URS and cloacal membrane, ultimately inhibiting the hindgut development and resulting in ARMs.

The series of smooth muscle structures in the pelvic floors of men: Dynamic coordination of smooth and skeletal muscles

Introduction

Recent studies have revealed the extended nature of smooth muscle structures in the pelvic floor, revising the conventional understanding of the “perineal body.” Our aim was to clarify the three‐dimensional configuration and detailed histological properties of the smooth muscle structures in the region anterior to the rectum and anal canal in men.

Materials and methods

Four male cadavers were subjected to macroscopic and immunohistological examinations. The pelvis was dissected from the perineal side, as in the viewing angle during transperineal surgeries. Serial transverse sections of the region anterior to the rectum and anal canal were stained with Masson's trichrome and immunohistological stains to identify connective tissue, smooth muscle, and skeletal muscle.

Results

There was a series of smooth muscle structures continuous with the longitudinal muscle of the rectum in the central region of the pelvic floor, and three representative elements were identified: the anterior bundle of the longitudinal muscle located between the external anal sphincter and bulbospongiosus; bilateral plate‐like structures with transversely‐oriented and dense smooth muscle fibers; and the rectourethral muscle located between the rectum and urethra. In addition, hypertrophic tissue with smooth muscle fibers extended from the longitudinal muscle in the anterolateral portion of the rectum and contacted the levator ani.

Conclusions

The series of smooth muscle structures had fiber orientations and densities that differed among locations. The widespread arrangement of the smooth muscle in the pelvic floor suggests a mechanism of dynamic coordination between the smooth and skeletal muscles.