Neonatal cochlear Lgr5+ progenitors retain limited hair cells (HCs) regenerative capacity, but the regulatory network remains incompletely defined. Serpin family E member 2 (Serpine2) is shown to participate in regulating proliferation and differentiation of cochlear Lgr5+ progenitors in the previous in vitro study. Here, the expression pattern and in vivo roles of Serpine2 in HC regeneration are explored by transgenic mice. It is found that Serpine2 is expressed in the mouse cochlea after birth with a downward trend as the mice age. In addition, Serpine2 conditional overexpression in vivo in Lgr5+ progenitors of neonatal mice cochlea results in an increased number of ectopic HCs in a dose-dependent manner. Serpine2 knockdown ex vivo and in vivo can inhibit HC regeneration. EdU assay and lineage tracing assay demonstrate these ectopic HCs likely originate from Lgr5+ progenitors through direct transdifferentiation rather than through mitotic regeneration. Moreover, single-nucleus RNA sequencing analysis and mRNA level validation reveal that conditionally overexpressed Serpine2 likely induces HC regeneration via inhibiting sonic hedgehog (SHH) signal pathway and inducing Atoh1 and Pou4f3 transcription factor. In brief, these data indicate that Serpine2 plays a pivotal role in HC regeneration from Lgr5+ progenitors in the neonatal mouse cochlea, and this suggests a new avenue for future research into HC regeneration.

[This corrects the article DOI: 10.3389/fgene.2021.625867.].

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.

BackgroundIn recent years gut microbiota has been found to play an important role in the occurrence and development of various chronic diseases, and diet is an important factor influencing gut microbiota. However, the effects of maternal high-fat diet in pre-pregnancy and pregnancy-and-lactation periods on offspring gut microbiota are still unclear.ObjectiveTo investigate the effects of maternal high-fat diet in pre-pregnancy and pregnancy-and-lactation periods on gut microbiota of offspring mice.MethodsC57BL/6J female mice were divided into four groups according to the diet patterns (high-fat diet, HFD; control diet, CD) given before and after conception, namely the pre-pregnancy control diet and post-pregnancy control diet group (CD-CD group), the pre-pregnancy control diet and post-pregnancy high-fat diet group (CD-HFD group), the pre-pregnancy high-fat diet and post-pregnancy control diet group (HFD-CD group), and the pre-pregnancy high-fact diet and post-pregnancy high-fat diet group (HFD-HFD group). Female mice were conceived in the same cage with male mice after 6 weeks of feeding, and the successfully conceived females continued to be randomly divided into two groups receiving either high-fat or control diet, and when the offspring mice were born, they were breastfed directly by the mothers, with each mother nursing only one offspring mouse. The number of offspring mice in each group was 6, with half males and half females. The body weight of offspring mice were recorded and body weight gain was compared between the four groups. After the lactational period, fresh feces of the offspring were collected, and the fecal DNA was extracted. Specific primers were designed according to the bacterial 16S rDNA(V3+V4) sequence and then the sequencing was performed using the Illumina HiSeq 2500 platform. Species annotation and operational taxonomic unit (OTU) analysis of sequencing data were conducted using QIMME, USEARCH and R software. In alpha diversity analysis, ACE and Chao1 indices were used to evaluate species richness, Shannon and Simpson indices considered both species richness and evenness. In beta diversity analysis, principal coordinates analysis (PCoA) and analysis of similarities (Anosim analyses) were used to find the differences in composition of gut microbiota between four groups, and line discriminant analysis effect size (LefSe) was conducted to identify which specific taxa contributed to the significant differences between groups.ResultsA greater effect of post-pregnancy diet on offspring body weight was observed, and the lowest body weight was recorded in the HFD-CD group during the whole experimental period. The results of OTU analysis showed that high-fat diet during post-pregnancy period reduced the number of OTUs in offspring mice, and the results of alpha diversity analysis showed that high-fat diet during post-pregnancy period reduced the richness of intestinal flora (ACE, P<0.05; Chao1, P<0.05), whereas differences in the α-diversity indices did not show statistical significance in the offspring mice with pre-pregnancy high-fat diet. The high-fat diet at different periods also led to changes in the dominant intestinal flora of the offspring. The high-fat diet during post-pregnancy period increased the abundance of Tenericutes (P<0.05), and decreased the abundance of Bacteroides, Epsilonbacteraeota, Cyanobacteria, and Deferribacteres (all Ps<0.05). At the genus level, high-fat diet during both pre-pregnancy and post-pregnancy periods decreased the abundance of Lactobacillus (P<0.05), and high-fat diet during pre-pregnancy period increased the abundance of Alistipes (P<0.05), while high-fat diet during post-pregnancy period increased the abundance of Lachnospira and Ruminococcus, and decreased the abundance of Muribaculaceae and Helicobacter (all Ps<0.05). The results of beta diversity analysis showed that the CD-CD group had a similar flora composition to the HFD-CD group, and the CD-HFD group had a similar flora composition to the HFD-HFD group, and the results of Anosim analysis showed statistically significant differences between groups (R=0.743, P<0.01). The LEfSe analysis counted all species with an effect on the differences between groups greater than the set value, which were Lactobacillus in the CD-CD group, Clostridiales in the CD-HFD group, Bacteroidetes and Helicobacters in the HFD-CD group, and Blautia, Ruminococcaceae, and Roseburia in the HFD-HFD group.ConclusionIt is found that varied effects of high-fat diet in different periods on the flora of the offspring mice. The high-fat diet during pre-pregnancy and post-pregnancy periods could reduce the abundance of Lactobacillus, but show different effects on the abundance of other intestinal flora such as Muribaculaceae, Lachnospiraceae, and Helicobacter differed. Diet during post-pregnancy period has a greater influence on modeling the offspring gut microbiota.

The cochlea is an important sensory organ for both balance and sound perception, and the formation of the cochlea is a complex developmental process. The development of the mouse cochlea begins on embryonic day (E)9 and continues until postnatal day (P)21 when the hearing system is considered mature. Small extracellular vesicles (sEVs), with a diameter ranging from 30 nm to 200 nm, have been considered as a significant medium for information communication in both the processing of physiological and pathological. However, there are no studies exploring the role of sEVs in the development of the cochlea. Here, we isolated tissue-derived sEVs from the cochleae of FVB mice at P3, P7, P14, and P21 by ultracentrifugation. These sEVs were first characterized by transmission electron microscopy, nanoparticle tracking analysis, and western blotting. Next, we used small RNA-seq and mass spectrometry to characterize the microRNA transcriptomes and proteomics of cochlear sEVs from mice at different ages. Many microRNAs and proteins were discovered to be related with inner ear development, anatomical structure development, and the auditory nervous system development. These results all suggest that sEVs exist in the cochlea and are likely to be essential for the normal development of the auditory system. Our findings provide many sEV microRNA and protein targets for future studies of the roles of cochlear sEVs.

Objective Cytotoxin associated protein A (CagA), the main virulence factor of Helicobacter pylori (Hp), plays an important role in the occurrence and development of gastric cancer. Micro RNA (miRNA) can promote or inhibit cancer by affecting the expression of downstream mRNA molecules. The aim of the study is to explore CagA-related miRNAs and effects of the miRNAs on gastric cancer for providing evidences to the diagnosis and treatment of gastric cancer correlated with Hp-CagA infection. MethodsMiRNAs related to both Hp infection and gastric cancer were screened in the Gene Expression Omnibus (GEO) database and relevant clinicopathological data were analyzed based on the Cancer Genome Atlas (TCGA) dataset. The prokaryotic expression system of CagA was constructed and AGS cells were transfected with different concentrations of CagA. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of the targeted miRNAs after transfection. Finally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the miRNA were predicted and analyzed with DIANAmirpath3.0 online websites. ResultsMiR-142-3p was confirmed being related Hp- CagA infection based on GEO database, TCGA dataset and cell experiment. In clinical studies, mir-142 expression was associated with the prognosis of male patients with stage I gastric cancer and female patients aged 45 – 54 and 55 – 64 years (all P < 0.05). In cytological studies, the expression of miR-142-3p was up-regulated in gastric cancer cells (P < 0.01) and the level of miR-142-3p expression was affected by Hp- CagA infection (P < 0.01). Other study results suggested that as downstream targets, phosphoinositide-3-kinase regulatory subunit 2 (PIK3R2), PIK3R5 and phosphoinositide-3 kinase, catalytic subunit delta (PIK3CD) may be closely related to the effect of miR-142-3p in progressing course of gastric cancer. ConclusionMiR-142-3p may promote gastric cancer progressing through pathways of PIK3R2/PIK3R5/PIK3CD and may be a potential therapeutic target.

Dync1li1, a subunit of cytoplasmic dynein 1, is reported to play important roles in intracellular retrograde transport in many tissues. However, the roles of Dync1li1 in the mammalian cochlea remain uninvestigated. Here we first studied the expression pattern of Dync1li1 in the mouse cochlea and found that Dync1li1 is highly expressed in hair cells (HCs) in both neonatal and adult mice cochlea. Next, we used Dync1li1 knockout (KO) mice to investigate its effects on hearing and found that deletion of Dync1li1 leads to early onset of progressive HC loss via apoptosis and to subsequent hearing loss. Further studies revealed that loss of Dync1li1 destabilizes dynein and alters the normal function of dynein. In addition, Dync1li1 KO results in a thinner Golgi apparatus and the accumulation of LC3+ autophagic vacuoles, which triggers HC apoptosis. We also knocked down Dync1li1 in the OC1 cells and found that the number of autophagosomes were significantly increased while the number of autolysosomes were decreased, which suggested that Dync1li1 knockdown leads to impaired transportation of autophagosomes to lysosomes and therefore the accumulation of autophagosomes results in HC apoptosis. Our findings demonstrate that Dync1li1 plays important roles in HC survival through the regulation of autophagosome transportation.

Helicobacter pylori (Hp) is a grade Ι carcinogen of gastric cancer (GC), and its high infection rate seriously affects human health. Cytotoxin-associated gene A (CagA) plays a key role in the carcinogenesis of Hp as one of its main virulence factors. miR-155-5p is abnormally expressed in patients with GC, associated with the occurrence and development of cancer. However, little is known about the association between CagA and miR-155-5p. (1) Background: This study explored the association and mechanism of CagA and miR-155-5p in GC. (2) Methods: The CagA sequence was obtained from the NCBI. After sequence optimization, it was connected to the pcDNA3.1 vector to construct a CagA eukaryotic expression plasmid (pcDNA-CagA). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to investigate the expression of miR-155-5p and CagA in GC cells. The function of CagA on GC cells was detected by CCK8, wound healing, and Transwell assays. Similarly, the function of miR-155-5p was also studied through the above functional experiments after the miR-155-5p overexpression and knockdown models had successfully been constructed. The associations among CagA, miR-155-5p, and SMAD2/SP1 were evaluated using RNA immunoprecipitation (RIP) and rescue experiments. (3) Results: The expression of miR-155-5p was significantly reduced in GC cells, and the expression of miR-155-5p was further reduced after CagA induction. Both overexpressed CagA and knockdown miR-155-5p cell models enhanced malignant transformation, whereas overexpressed miR-155-5p inhibited malignant transformation in vitro. The function of miR-155-5p on GC cells could be influenced by CagA. We also found that the influence of miR-155-5p on SMAD2 and SP1 could be regulated by CagA. (4) Conclusions: CagA potentially regulates the biological function of GC cells through the miR-155-5p/SMAD2/SP1 axis. miR-155-5p could be a therapeutic target for GC related to CagA.

The super elongation complex (SEC) has been reported to play a key role in the proliferation and differentiation of mouse embryonic stem cells. However, the expression pattern and function of the SEC in the inner ear has not been investigated. Here, we studied the inner ear expression pattern of three key SEC components, AFF1, AFF4, and ELL3, and found that these three proteins are all expressed in both cochlear hair cells (HCs)and supporting cells (SCs). We also cultured Lgr5+ inner ear progenitors in vitro for sphere-forming assays and differentiation assays in the presence of the SEC inhibitor flavopiridol. We found that flavopiridol treatment decreased the proliferation ability of Lgr5+ progenitors, while the differentiation ability of Lgr5+ progenitors was not affected. Our results suggest that the SEC might play important roles in regulating inner ear progenitors and thus regulating HC regeneration. Therefore, it will be very meaningful to further investigate the detailed roles of the SEC signaling pathway in the inner ear in vivo in order to develop effective treatments for sensorineural hearing loss.

Striatin-interacting protein 1 (Strip1) is a core component of the striatin interacting phosphatase and kinase (STRIPAK) complex, which is involved in embryogenesis and development, circadian rhythms, type 2 diabetes, and cancer progression. However, the expression and role of Strip1 in the mammalian cochlea remains unclear. Here we studied the expression and function of Strip1 in the mouse cochlea by using Strip1 knockout mice. We first found that the mRNA and protein expression of Strip1 increases as mice age starting from postnatal day (P) 3 and reaches its highest expression level at P30 and that the expression of Strip1 can be detected by immunofluorescent staining starting from P14 only in cochlear HCs, and not in supporting cells (SCs). Next, we crossed Strip1 heterozygous knockout (Strip +/−) mice to obtain Strip1 homozygous knockout (Strip1−/−) mice for studying the role of Strip1 in cochlear HCs. However, no Strip1−/− mice were obtained and the ratio of Strip +/− to Strip1+/+ mice per litter was about 2:1, which suggested that homozygous Strip1 knockout is embryonic lethal. We measured hearing function and counted the HC number in P30 and P60 Strip +/− mice and found that they had normal hearing ability and HC numbers compared to Strip1+/+ mice. Our study suggested that Strip1 probably play important roles in HC development and maturation, which needs further study in the future.

Background Nitric oxide (NO) and cyclic guanosine phosphate (cGMP) play important roles in blood pressure regulation, neurotransmitter delivery, renal function, and tumorigenesis and development. The intermediate link of this signaling pathway, soluble guanylyl cyclase (sGC), is particularly important. However, the role of the GUCY1A2 gene encoding the sGC α2 subunit is unknown. Methods Gene expression and clinical data were obtained from The Cancer Genome Atlas (TCGA) database. After screening for GUCY1A2 expression, the expression differences between gastric cancer (GC) tissues and adjacent noncancerous tissues were determined using R software. Quantitative real-time polymerase chain reaction (qRT-PCR) and meta-analysis were used to verify the result. The correlation between the expression of GUCY1A2 and clinicopathological parameters was explored by logistic regression. Then, Kaplan-Meier survival analysis and the Cox proportional hazards regression were used to evaluate the relationship between the expression of GUCY1A2 and the survival of GC patients. Finally, gene set enrichment analysis (GSEA) was used to explore and analyze the GC-related signaling pathways affected by high GUCY1A2 expression. Results We found that GUCY1A2 was highly expressed in GC tissues compared to adjacent noncancerous tissues (P < 0.001). qRT-PCR (P < 0.001) and meta-analysis (SMD = 0.65, 95% CI: 0.20-1.10) confirmed the difference in GUCY1A2 expression. Logistic regression analysis showed that high expression of GUCY1A2 was associated with histological grade (OR=1.858 for poor vs. well or moderate, P = 0.004) and T stage (OR = 3.389 for T3 vs. T1, P = 0.025; OR = 3.422 for T4 vs. T1, P = 0.028). Kaplan-Meier curves indicated that GC patients with high expression of GUCY1A2 had a poor prognosis than that of patients with low expression. Univariate analysis indicated that GUCY1A2 and some clinicopathological parameters, such as age, pathological stage, and TNM stage, may predict poor prognosis. Multivariate analysis further confirmed that GUCY1A2 was an independent prognostic marker (HR = 1.699; 95%CI, 1.175-2.456; P = 0.005). GSEA showed that the high GUCY1A2 phenotype is significantly enriched for tumor-associated signaling pathways. Conclusions GUCY1A2 is highly expressed in GC and may be used as a potential prognostic marker.

Background: Lumican (LUM) is a member of the small leucine-rich proteoglycan family and plays dual roles as an oncogene and a tumor suppressor gene. The effect of LUM on tumors is still controversial. Methods: Gene expression profiles and clinical data of gastric cancer (GC) were downloaded from The Cancer Genome Atlas (TCGA) database. The expression difference of LUM in GC tissues and adjacent nontumor tissues was analyzed by R software and verified by quantitative real-time polymerase chain reaction (qRT-PCR) and comprehensive meta-analysis. The relationship between LUM expression and clinicopathological parameters was assessed by chi-square test and logistic regression. Kaplan–Meier survival analysis and Cox proportional hazards regression model were chosen to assess the effect of LUM expression on survival. Gene set enrichment analysis (GSEA) was used to screen the signaling pathways involved in GC between the low and the high LUM expression datasets. Results: The expression of LUM in GC tissues was significantly higher than that in adjacent nontumor tissues (P < 0.001) from the TCGA database. qRT-PCR (P = 0.022) and comprehensive meta-analysis (standard mean difference = 0.90, 95% CI: 0.34–1.46) demonstrated that LUM was upregulated in GC. The chi-square test showed that the high expression of LUM was correlated with tumor differentiation (P = 0.024) and T stage (P = 0.004). Logistic regression analysis showed that high LUM expression was significantly correlated with tumor differentiation (OR = 1.543 for poor vs. well or moderate, P = 0.043), pathological stage (OR = 3.149 for stage II vs. stage I, P = 0.001; OR = 2.505 for stage III vs. stage I, P = 0.007), and T classification (OR = 13.304 for T2 vs. T1, P = 0.014; OR = 18.434 for T3 vs. T1, P = 0.005; OR = 30.649 for T4 vs. T1, P = 0.001). The Kaplan–Meier curves suggested that patients with high LUM expression had a poor prognosis. Multivariate analysis showed that a high expression of LUM was an important independent predictor of poor overall survival (HR, 1.189; 95% CI, 1.011–1.400; P = 0.037). GSEA indicated that 14 signaling pathways were evidently enriched in samples with the high-LUM expression phenotype. Conclusions: LUM might act as an oncogene in the progression of GC and could be regarded as a potential prognostic indicator and therapeutic target for GC.