Conditional Overexpression of Net1 Enhances the Trans-Differentiation of Lgr5+ Progenitors into Hair Cells in the Neonatal Mouse Cochlea

Sensorineural hearing loss is mainly caused by damage to hair cells (HC), which cannot be regenerated spontaneously in adult mammals once damaged. Cochlear Lgr5+ progenitors are characterised by HC regeneration capacity in neonatal mice, and we previously screened several new genes that might induce HC regeneration from Lgr5+ progenitors. Net1, a guanine nucleotide exchange factor, is one of the screened new genes and is particularly active in cancer cells and is involved in cell proliferation and differentiation. Here, to explore in vivo roles of Net1 in HC regeneration, Net1 loxp/loxp mice were constructed and crossed with Lgr5 CreER/+ mice to conditionally overexpress (cOE) Net1 in cochlear Lgr5+ progenitors. We observed a large number of ectopic HCs in Lgr5 CreER/+ Net1 loxp/loxp mouse cochlea, which showed a dose-dependent effect. Moreover, the EdU assay was unable to detect any EdU+/Sox2+ supporting cells, while lineage tracing showed significantly more regenerated tdTomato+ HCs in Lgr5 CreER/+ Net1 loxp/loxp tdTomato mice, which indicated that Net1 cOE enhanced HC regeneration by inducing the direct trans-differentiation of Lgr5+ progenitors rather than mitotic HC regeneration. Additionally, qPCR results showed that the transcription factors related to HC regeneration, including Atoh1, Gfi1 and Pou4f3, were significantly upregulated and are probably the mechanism behind the HC regeneration induced by Net1. In conclusion, our study provides new evidence for the role of Net1 in enhancing HC regeneration in the neonatal mouse cochlea.

Enzymatic degraded polysaccharides from Enteromorpha prolifera inhibit the growth of THP-1 cells and induce apoptosis via the mitochondrial pathway

Polysaccharides from Enteromorpha prolifera (EP) is a kind of sulfated polysaccharides with complex structure. Several reports have showed that EP play roles in antioxidant and anti-inflammatory, while, whose function in anti-leukemia is still poorly understood. In this work, EPH were the hydrolysis products of EP by ulvan lyase EPL15085, which displayed lower molecular weight and enhanced sulfate groups than EP. Importantly, EPH exhibited effective inhibitory effect on the human leukemia monocyte cell line, THP-1 cells, however, the EP treated group showed no significant change. Results of JC-1 staining and ROS assay showed mitochondrial dysfunction after EPH treatment, and the increased rate of Bax/Bcl ultimately activated Caspase family proteins to induce apoptosis, indicating the mitochondrial pathway was involved. This study demonstrates the enzymatic products of EP showed enhanced effect on anti-leukemia, which would provide insights for approaches to uncover novel physiological functions of marine polysaccharides and potential therapy for acute myeloid leukemia patients.

Circular RNAs in ferroptosis: regulation mechanism and potential clinical application in disease

Ferroptosis, an iron-dependent non-apoptotic form of cell death, is reportedly involved in the pathogenesis of various diseases, particularly tumors, organ injury, and degenerative pathologies. Several signaling molecules and pathways have been found to be involved in the regulation of ferroptosis, including polyunsaturated fatty acid peroxidation, glutathione/glutathione peroxidase 4, the cysteine/glutamate antiporter system Xc-, ferroptosis suppressor protein 1/ubiquinone, and iron metabolism. An increasing amount of evidence suggests that circular RNAs (circRNAs), which have a stable circular structure, play important regulatory roles in the ferroptosis pathways that contribute to disease progression. Hence, ferroptosis-inhibiting and ferroptosis-stimulating circRNAs have potential as novel diagnostic markers or therapeutic targets for cancers, infarctions, organ injuries, and diabetes complications linked to ferroptosis. In this review, we summarize the roles that circRNAs play in the molecular mechanisms and regulatory networks of ferroptosis and their potential clinical applications in ferroptosis-related diseases. This review furthers our understanding of the roles of ferroptosis-related circRNAs and provides new perspectives on ferroptosis regulation and new directions for the diagnosis, treatment, and prognosis of ferroptosis-related diseases.

Molecular regulation of Nodal signaling during mesendoderm formation

One of the most important events during vertebrate embryogenesis is the formation or specification of the three germ layers, endoderm, mesoderm, and ectoderm. After a series of rapid cleavages, embryos form the mesendoderm and ectoderm during late blastulation and early gastrulation. The mesendoderm then further differentiates into the mesoderm and endoderm. Nodal, a member of the transforming growth factor β (TGF-β) superfamily, plays a pivotal role in mesendoderm formation by regulating the expression of a number of critical transcription factors, including Mix-like, GATA, Sox, and Fox. Because the Nodal signal transduction pathway is well-characterized, increasing effort has been made to delineate the spatiotemporal modulation of Nodal signaling during embryonic development. In this review, we summarize the recent progress delineating molecular regulation of Nodal signal intensity and duration during mesendoderm formation.