Sacral Neural Crest-Independent Origin of the Enteric Nervous System in Mouse.

BACKGROUND & AIMS: The enteric nervous system (ENS), the gut's intrinsic nervous system critical for gastrointestinal function and gut-brain communication, is believed to mainly originate from vagal neural crest cells (vNCCs) and partially from sacral NCCs (sNCCs). Resolving the exact origins of the ENS is critical for understanding congenital ENS diseases but has been confounded by the inability to distinguish between both NCC populations in situ. Here, we aimed to resolve the exact origins of the mammalian ENS. METHODS: We genetically engineered mouse embryos facilitating comparative lineage-tracing of either all (pan-) NCCs including vNCCs or caudal trunk and sNCCs (s/tNCCs) excluding vNCCs. This was combined with dual-lineage tracing and 3-dimensional reconstruction of pelvic plexus and hindgut to precisely pinpoint sNCC and vNCC contributions. We further used coculture assays to determine the specificity of cell migration from different neural tissues into the hindgut. RESULTS: Both pan-NCCs and s/tNCCs contributed to established NCC derivatives but only pan-NCCs contributed to the ENS. Dual-lineage tracing combined with 3-dimensional reconstruction revealed that s/tNCCs settle in complex patterns in pelvic plexus and hindgut-surrounding tissues, explaining previous confusion regarding their contributions. Coculture experiments revealed unspecific cell migration from autonomic, sensory, and neural tube explants into the hindgut. Lineage tracing of ENS precursors lastly provided complimentary evidence for an exclusive vNCC origin of the murine ENS. CONCLUSIONS: sNCCs do not contribute to the murine ENS, suggesting that the mammalian ENS exclusively originates from vNCCs. These results have immediate implications for comprehending (and devising treatments for) congenital ENS disorders, including Hirschsprung's disease.

FAM134B oligomerization drives endoplasmic reticulum membrane scission for ER-phagy.

Degradation of endoplasmic reticulum (ER) by selective autophagy (ER-phagy) is crucial for ER homeostasis. However, it remains unclear how ER scission is regulated for subsequent autophagosomal sequestration and lysosomal degradation. Here, we show that oligomerization of ER-phagy receptor FAM134B (also referred to as reticulophagy regulator 1 or RETREG1) through its reticulon-homology domain is required for membrane fragmentation in vitro and ER-phagy in vivo. Under ER-stress conditions, activated CAMK2B phosphorylates the reticulon-homology domain of FAM134B, which enhances FAM134B oligomerization and activity in membrane fragmentation to accommodate high demand for ER-phagy. Unexpectedly, FAM134B G216R, a variant derived from a type II hereditary sensory and autonomic neuropathy (HSAN) patient, exhibits gain-of-function defects, such as hyperactive self-association and membrane scission, which results in excessive ER-phagy and sensory neuron death. Therefore, this study reveals a mechanism of ER membrane fragmentation in ER-phagy, along with a signaling pathway in regulating ER turnover, and suggests a potential implication of excessive selective autophagy in human diseases.

CLASRP oncogene as a novel target for colorectal cancer.

Clk4-associated serine/arginine-rich protein (CLASRP), an alternative splicing regulator, may be involved in the development and progression of cancer by regulating the activity of the CDC-like kinase (Clk) family. This study explored the biological function of CLASRP in colorectal cancer (CRC). The expression of CLASRP, which is associated with clinicopathological features, was analysed in CRC tissues and paired noncancer tissues by RT-PCR. The roles of CLASRP were investigated in CRC cells transfected with plasmids or shRNA through proliferation, migration and invasion assays in vitro and a xenograft model in vivo. Apoptosis was analysed using CLASRP-overexpressing CRC cells by western blotting. Clk inhibitors were used to perform functional research on CLASRP in CLASRP-overexpressing CRC cells. CLASRP was significantly upregulated in CRC cell lines, while high CLASRP expression was correlated with metastasis in CRC patients. Functionally, overexpression of CLASRP significantly promoted the proliferation, migration and invasion of CRC cells in vitro and tumour growth in vivo. Mechanistically, the proliferation, migration and invasion of CLASRP-overexpressing CRC cells were inhibited by Clk inhibitors, accompanied by low expression of CLASRP at the gene and protein levels. Clk inhibitors induced apoptosis of CLASRP-overexpressing CRC cells, resulting in direct blockade of cell growth. The expression levels of cleaved caspase 3 and cleaved caspase 8 were increased in CLASRP-overexpressing CRC cells treated with Clk inhibitors. CLASRP might serve as a promotional oncogene in CRC cells and be suppressed by Clk inhibitors through activation of caspase pathways.

Mapping of Extrinsic Innervation of the Gastrointestinal Tract in the Mouse Embryo.

Precise extrinsic afferent (visceral sensory) and efferent (sympathetic and parasympathetic) innervation of the gut is fundamental for gut-brain cross talk. Owing to the limitation of intrinsic markers to distinctively visualize the three classes of extrinsic axons, which intimately associate within the gut mesentery, detailed information on the development of extrinsic gut-innervating axons remains relatively sparse. Here, we mapped extrinsic innervation of the gut and explored the relationships among various types of extrinsic axons during embryonic development in mice. Visualization with characterized intrinsic markers revealed that visceral sensory, sympathetic, and parasympathetic axons arise from different anatomic locations, project in close association via the gut mesentery, and form distinctive innervation patterns within the gut from embryonic day (E)10.5 to E16.5. Genetic ablation of visceral sensory trajectories results in the erratic extension of both sympathetic and parasympathetic axons, implicating that afferent axons provide an axonal scaffold to route efferent axons. Coculture assay further confirmed the attractive effect of sensory axons on sympathetic axons. Taken together, our study provides key information regarding the development of extrinsic gut-innervating axons occurring through heterotypic axonal interactions and provides an anatomic basis to uncover neural circuit assembly in the gut-brain axis (GBA).SIGNIFICANCE STATEMENT Understanding the development of extrinsic innervation of the gut is essential to unravel the bidirectional neural communication between the brain and the gut. Here, with characterized intrinsic markers targeting vagal sensory, spinal sensory, sympathetic, and parasympathetic axons, respectively, we comprehensively traced the spatiotemporal development of extrinsic axons to the gut during embryonic development in mice. Moreover, in line with the somatic nervous system, pretarget sorting via heterotypic axonal interactions is revealed to play critical roles in patterning extrinsic efferent trajectories to the gut. These findings provide basic anatomic information to explore the mechanisms underlying the process of assembling neural circuitry in the gut-brain axis (GBA).

Endothelin-1-Endothelin receptor B complex contributes to oligodendrocyte differentiation and myelin deficits during preterm white matter injury.

Preterm cerebral white matter injury (WMI), a major form of prenatal brain injury, may potentially be treated by oligodendrocyte (OL) precursor cell (OPC) transplantation. However, the defective differentiation of OPCs during WMI seriously hampers the clinical application of OPC transplantation. Thus, improving the ability of transplanted OPCs to differentiate is critical to OPC transplantation therapy for WMI. We established a hypoxia-ischemia-induced preterm WMI model in mice and screened the molecules affected by WMI using single-cell RNA sequencing. We revealed that endothelin (ET)-1 and endothelin receptor B (ETB) are a pair of signaling molecules responsible for the interaction between neurons and OPCs and that preterm WMI led to an increase in the number of ETB-positive OPCs and premyelinating OLs. Furthermore, the maturation of OLs was reduced by knocking out ETB but promoted by stimulating ET-1/ETB signaling. Our research reveals a new signaling module for neuron-OPC interaction and provides new insight for therapy targeting preterm WMI.

Serum VEGF levels as a predictor of recurrence in patients with advanced­stage esophageal squamous cell carcinoma following curative esophagectomy followed by chemotherapy or concurrent radiotherapy.

The present study evaluated serum levels of vascular endothelial growth factor (VEGF) as a predictor of recurrence in patients with advanced-stage esophageal squamous cell carcinoma (ESCC) following curative esophagectomy followed by chemotherapy or concurrent radiotherapy. Patients with locally advanced resectable ESCC underwent R0 esophagectomy followed by chemotherapy or concurrent radiotherapy as an adjuvant. Serum VEGF levels in 173 patients, including 57 patients with recurrent disease, and 183 healthy controls were determined using a Luminex assay. The results demonstrated that the serum VEGF levels were significantly higher in 57 patients with locally advanced resectable ESCC at recurrence compared with the levels at pre-treatment (P<0.001). The patients with recurrence exhibited significantly higher serum VEGF levels during chemotherapy or concurrent radiotherapy than patients with no recurrence (P<0.05). Patients with low serum VEGF levels had a significantly longer survival time than those with high serum VEGF levels prior to treatment (P<0.01). The median survival times were 70 and 25 months in patients with locally advanced resectable ESCC with serum VEGF levels <161.75 and ≥161.75 pg/ml following treatment, respectively (P<0.01). Compared with patients with VEGF levels <147 pg/ml following treatment, patients with locally advanced resectable ESCC with VEGF levels ≥147 pg/ml had a significantly higher risk of recurrence (P<0.01). Patients with low serum VEGF levels (<147 pg/ml) had significantly higher recurrence-free survival rates than those with high serum VEGF levels (≥147 pg/ml) following treatment (P<0.01). The findings of the present study demonstrate that serum VEGF levels are a potential predictor of recurrence and of the treatment outcomes of chemotherapy or concurrent radiotherapy in patients with locally advanced resectable ESCC.

miR319 and its target TCP4 involved in plant architecture regulation in Brassica napus.

Plant architecture is a collection of genetically controlled crop productivity and adaptation. MicroRNAs (miRNAs) have been proved to function in various biological processes, but little is known about how miRNA regulates plant architecture in rapeseed (Brassica napus L.). In this study, four small RNA libraries and two degradome libraries from shoot apex of normal and rod-like plants were sequenced. A total of 639 miRNA precursors and 16 differentially expressed miRNAs were identified in this study. In addition, 322 targets were identified through degradome sequencing. Among them, 14 targets were further validated via RNA ligase-mediated 5' rapid amplification of cDNA ends. Transgenic approach showed that increased TCP4 activity in Arabidopsis resulted in premature onset of maturation and reduced plant size along with early flowering and shortened flowering time. miR319-OE lines in Brassica napus exhibited serrated leaves and abnormal development of shoot apical meristem (SAM), which led to the deformed growth of stem and reduced plant height. In conclusion, our study lays the foundation for elucidating miRNA regulate plant architecture and provides new insight into the miR319/TCP4 module regulates plant architecture in rapeseed.

A regulatory circuit comprising the CBP and SIRT7 regulates FAM134B-mediated ER-phagy.

Macroautophagy (autophagy) utilizes a serial of receptors to specifically recognize and degrade autophagy cargoes, including damaged organelles, to maintain cellular homeostasis. Upstream signals spatiotemporally regulate the biological functions of selective autophagy receptors through protein post-translational modifications (PTM) such as phosphorylation. However, it is unclear how acetylation directly controls autophagy receptors in selective autophagy. Here, we report that an ER-phagy receptor FAM134B is acetylated by CBP acetyltransferase, eliciting intense ER-phagy. Furthermore, FAM134B acetylation promoted CAMKII-mediated phosphorylation to sustain a mode of milder ER-phagy. Conversely, SIRT7 deacetylated FAM134B to temper its activities in ER-phagy to avoid excessive ER degradation. Together, this work provides further mechanistic insights into how ER-phagy receptor perceives environmental signals for fine-tuning of ER homeostasis and demonstrates how nucleus-derived factors are programmed to control ER stress by modulating ER-phagy.

Mesenteric Neural Crest Cells Are the Embryological Basis of Skip Segment Hirschsprung's Disease.

BACKGROUND & AIMS: Defective rostrocaudal colonization of the gut by vagal neural crest cells (vNCCs) results in Hirschsprung's disease (HSCR), which is characterized by aganglionosis in variable lengths of the distal bowel. Skip segment Hirschsprung's disease (SSHD), referring to a ganglionated segment within an otherwise aganglionic intestine, contradicts HSCR pathogenesis and underscores a significant gap in our understanding of the development of the enteric nervous system. Here, we aimed to identify the embryonic origin of the ganglionic segments in SSHD. METHODS: Intestinal biopsy specimens from HSCR patients were prepared via the Swiss-roll technique to search for SSHD cases. NCC migration from the neural tube to the gut was spatiotemporally traced using targeted cell lineages and gene manipulation in mice. RESULTS: After invading the mesentery surrounding the foregut, vNCCs separated into 2 populations: mesenteric NCCs (mNCCs) proceeded to migrate along the mesentery, whereas enteric NCCs invaded the foregut to migrate along the gut. mNCCs not only produced neurons and glia within the gut mesentery, but also continuously complemented the enteric NCC pool. Two new cases of SSHD were identified from 183 HSCR patients, and Ednrb-mutant mice, but not Ret-/- mice, showed a high incidence rate of SSHD-like phenotypes. CONCLUSIONS: mNCCs, a subset of vNCCs that migrate into the gut via the gut mesentery to give rise to enteric neurons, could provide an embryologic explanation for SSHD. These findings lead to novel insights into the development of the enteric nervous system and the etiology of HSCR.