MZB1-mediated IgA secretion suppresses the development and progression of colorectal cancer triggered by gut inflammation.

Colorectal cancer (CRC) ranks among the top causes of mortality globally. Gut inflammation is one crucial risk factor that augments CRC development since patients suffering from inflammatory bowel disease have an increased incidence of CRC. The role of immunoglobulin (Ig)A in maintaining gut homeostasis and preventing inflammation has been well established. Our earlier work demonstrated that the marginal zone and B1 cell-specific protein (MZB1) promotes gut IgA secretion and its absence results in pronounced dextran sulfate sodium salt (DSS)-induced colitis. In the present study, we explored the role of MZB1 in CRC development using the azoxymethane (AOM)/DSS-induced CRC model. We observed an increase in both the number and size of the tumor nodules in Mzb1-/- mice compared with Mzb1+/+ mice. The increase in CRC development and progression in Mzb1-/- mice was associated with reduced intestinal IgA levels, altered gut flora, and more severe gut and systemic inflammation. Oral administration of the monoclonal IgA, W27, alleviated both the gut inflammation and AOM/DSS-induced CRC. Notably, cohousing Mzb1+/+ and Mzb1-/- mice from the 10th day after birth led to similar CRC development. Our findings underscore the pivotal role of MZB1-mediated IgA secretion in suppressing the onset and progression of CRC triggered by gut inflammation. Moreover, our study highlights the profound impact of microbiota composition, modulated by gut IgA levels, on gut inflammation. Nonetheless, establishing a direct correlation between the severity of colitis and subsequent CRC development and the presence or absence of a particular microbiota is challenging.

[Chronic Injury of Mice Bone Marrow Multipotent Hematopoietic Progenitor Cells Induced by Ionizing Radiation].

OBJECTIVE: To explore the chronic injury and its possible mechanism of ionizing radiation on multipotent hematopoietic progenitor cells (MPPs) by determining the related indicators of MPPs in bone marrow of mice post-radiation. METHODS: Sixteen C57BL/6 adult mice were randomly divided into normal control and irradiation groups, 8 mice in each group. The mice in irradiation group were exposed to 6 Gy X-ray. The proportion of bone marrow MPPs, their apoptosis and proliferation 2 months after irradiation were detected by flow cytometry. Mitochondrial activity and levels of reactive oxygen species (ROS) in each MPPs population were detected by Mitotracker Red and DCFDA probes, and the senescent state of MPPs in the bone marrow was analyzed. RESULTS: Ionizing radiation could reduce the proportion of MPPs in mouse bone marrow. The proportions and numbers of MPP1, MPP3 and MPP4 in the bone marrow were significantly decreased after whole-body irradiation with 6 Gy X-ray (P<0.05). In addition, radiation significantly reduced the colony-forming capacity of MPPs in bone marrow (P<0.05), the proportions of apoptotic cells in the MPP1 and MPP4 cell populations increased significantly in the bone marrow (P<0.05). The activity of mitochondria was significantly reduced in the bone marrow MPP2, MPP3 and MPP4 cell populations compared with that of the control group (P<0.05). It was also found that the radiation could significantly increase the ROS levels of MPPs in bone marrow, and the content of ROS in the MPP2, MPP3 and MPP4 cell population of the bone marrow was significantly increased(P<0.05). The senescent cells ratios of MPP1, MPP3 and MPP4 cells in the bone marrow after irradiation were significantly higher than those in the control group (P<0.05). CONCLUSION: Ionizing radiation can cause chronic MPPs damage in mice, which is closely associated with persistent oxidative stress, cells apoptosis, and cellular senescence.

CAMTA1 gene affects the ischemia-reperfusion injury by regulating CCND1.

Epigenetic modulations lead to changes in gene expression, including DNA methylation, histone modifications, and noncoding RNAs. In recent years, epigenetic modifications have been related to the pathogenesis of different types of cancer, cardiovascular disease, and other diseases. Emerging evidence indicates that DNA methylation could be associated with ischemic stroke (IS) and plays a role in pathological progression, but the underlying mechanism has not yet been fully understood. In this study, we used human methylation 850K BeadChip to analyze the differences in gene methylation status in the peripheral blood samples from two groups (3 IS patients vs. 3 healthy controls). According to their bioinformatics profiling, we found 278 genes with significantly different methylation levels. Seven genes with the most significant methylation modifications were validated in two expanded groups (100 IS patients vs. 100 healthy controls). The CAMTA1 gene had significantly different methylation changes in patients compared to the controls. To understand the CAMTA1 function in stroke, we generated CAMTA1 knockout in SH-SY5Y cells. RNA seq results in CAMTA1 knockout cells revealed the pathways and gene set enrichments involved in cellular proliferation and cell cycle. Furthermore, a series of experiments demonstrated that in the oxygen-glucose deprivation/re-oxygenation (OGD/R) model system, the expression of cyclin D1, an essential regulator of cell cycle progression, was increased in SH-SY5Y CAMTA1 KO cells. Increasing evidence demonstrated that ischemic stress could inappropriately raise cyclin D1 levels in mature neurons. However, the molecular signals leading to an increased cyclin D1 level are unclear. Our findings demonstrate for the first time that the CAMTA1 gene could regulate cyclin D1 expression and implicate their role in strokes.

Decrease of MtDNA copy number affects mitochondrial function and involves in the pathological consequences of ischaemic stroke.

The mtDNA copy number can affect the function of mitochondria and play an important role in the development of diseases. However, there are few studies on the mechanism of mtDNA copy number variation and its effects in IS. The specific mechanism of mtDNA copy number variation is still unclear. In this study, mtDNA copy number of 101 IS patients and 101 normal controls were detected by qRT-PCR, the effect of D-loop variation on mtDNA copy number of IS patients was explored. Then, a TFAM gene KD-OE PC12 cell model was constructed to explore the effect of mtDNA copy number variation on mitochondrial function. The results showed that the mtDNA copy number level of the IS group was significantly lower than that of the normal control group (p < 0.05). The relative expression of TFAM gene mRNA in the cells of the OGD/R treatment group was significantly lower than that of the control group (p < 0.05). In addition, after TFAM gene knockdown and over-expression plasmids were transfected into HEK 293T cells, mtDNA copy number and ATP production level of Sh-TFAM transfection group was significantly decreased (p < 0.05), while mtDNA copy number and ATP production level of OE-TFAM transfected group were significantly higher than that of blank control group and OE-ctrl negative control group (p < 0.01). Our study demonstrated that mitochondrial D-loop mutation and TFAM gene dysfunction can cause the decrease of mtDNA copy number, thus affecting the mitochondrial metabolism and function of nerve cells, participating in the pathological damage mechanism of IS.

Rapamycin Ameliorates Radiation-Induced Testis Damage in Mice.

Male infertility is an important problem in human and animal reproduction. The testis is the core of male reproduction, which is very sensitive to radiation. The decline of male reproductive ability is a common trend in the world. Radiation is a physical factor leading to abnormal male reproductive function. To investigate the potential mechanisms of testicular damage induced by radiation and explore effective strategies to alleviate radiation-induced testis injury, C57BL/6 mice were irradiated with 8.0 Gy of X-ray irradiation. Testis and epididymis were collected at days 1, 3, and 7 after radiation exposure to analyze spermatogonia and sperm function. The results showed that radiation significantly destroyed testicular structure and reduced the numbers of spermatogonia. These were associated with mTORC1 signaling activation, decreased cellular proliferation and increased apoptotic cells in the irradiated testis. Rapamycin significantly blocked mTORC1 signaling pathway in the irradiated testis. Inhibition of mTORC1 signaling pathway by rapamycin treatment after radiation could significantly improve cell proliferation in testis and alleviate radiation-induced testicular injury after radiation exposure. Rapamycin treatment benefited cell survival in testis to maintain spermatogenesis cycle at 35 days after irradiation. These findings imply that rapamycin treatment can accelerate testis recovery under radiation condition through inhibiting mTORC1 signaling pathway.

Genetic variations in ABCA1/G1 associated with plasma lipid levels and risk of ischemic stroke.

BACKGROUND: ATP binding cassette transporters ABCA1 and ABCG1 play a crucial role in cholesterol efflux and reverse cholesterol transport (RCT), thereby rendering ischemic stroke (IS) susceptibility. Variants of ABCA1/G1 have been implicated in etiology of IS. This study aimed to investigate the association between single-nucleotide polymorphisms (SNPs) of ABCA1/G1 with plasma lipid variability and the risk of IS in Chinese Han Population. METHODS: Totally 249 IS patients and 226 healthy controls were enrolled and 10 SNPs of ABCA1/G1 were screened for genotyping by kompetitive allele-specific polymerase chain reaction (KASP) and validated by sanger sequencing. The logistic regression analysis was performed to identify risk alleles of IS and appropriate genetic model. The genetic risk scores (GRS) and predicted risks for all individuals was computed. Based on different plasma lipid levels, we applied stratified analyses for subgroups. Linkage disequilibrium (LD) test was used to explore different functional haplotype combinations. Association between specific allele or genotype of the SNPs of ABCA1/G1 and plasma lipid or lipoproteins levels were also investigated. RESULTS: Besides total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), significant differences of clinical data were observed between IS and control group. The rare GG genotype frequencies of rs4149338 on ABCA1 was higher in IS patients than those in controls (11.4%, 4.6%, respectively, P = 0.037). Frequencies of rs57137919 on ABCG1 for rare AA genotype was lower in IS group than those in control group (4.6%, 13.3%, respectively, P = 0.030). GRS showed ability to discriminate IS patients and controls (AUC = 0.633, P < 0.001). Haplotype A-A (rs4149339-rs4149338) was correlated with reduced risk of IS (P = 0.023). Association analysis showed that subjects with rare AA genotype of rs57137919 had the lowest LDL-C levels while rare GG genotype of rs4149338 had lower TC level than those with AA genotype. The mRNA expression of ABCG1 was higher in IS patients, especially in the patients with frequent GG genotype of rs57137919, and was positively correlated with higher ABCG1 expression level and plasma LDL-C level. CONCLUSIONS: Polymorphisms of ABCA1/G1 associated with varieties of plasma lipid levels and risk of IS.

Epigenetic regulation mechanism of DNA methylation and miRNAs on the expression of the ALOX5AP gene in patients with ischemic stroke.

5-lipoxygenase-activating protein (FLAP), encoded by the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene, can adjust the biogenesis of proinflammatory leukotrienes to increase the adhesion and permeability of the vascular internal wall. Moreover, it participates in the process of atherosclerosis and is closely associated with ischemic stroke (IS). Accumulating evidence has shown that the expression levels of the ALOX5AP gene are upregulated in patients with IS. However, the mechanism of ALOX5AP action in IS remain elusive. The present study hypothesized that epigenetic regulation, including DNA methylation and microRNA (miR/miRNA) regulation, affects the expression levels of the ALOX5AP gene. Therefore, 200 patients with a first diagnosis of acute IS and 200 healthy control subjects were enrolled in the present study. Initially, the mRNA expression levels of the ALOX5AP gene were examined by reverse transcription-quantitative PCR. It was found that the mRNA levels of ALOX5AP gene in the IS group were significantly higher compared with controls (P<0.05). Subsequently, the methylation status of 17 CpG sites located in the promoter region of ALOX5AP was assessed by MethyTarget sequencing. However, the levels of methylation exhibited no significant differences between IS and control groups (P>0.05). Moreover, the expression levels of miR-335 and miR-495 were examined as two potential miRNAs targeting the ALOX5AP gene. The expression levels of miR-335 and miR-495 in the IS group were significantly lower compared with the control group (P<0.05). Finally, the luciferase assay results indicated that the luciferase activity of the experimental group following co-transfection of miRNA mimic and wild-type reporter gene plasmid was significantly lower compared with the other experimental groups (P<0.05), suggesting that miR-335 and miR-495 could specifically bind to the 3'-untranslated region of the ALOX5AP gene, thereby downregulating its expression. The present study provided preliminary evidence demonstrating that epigenetic regulation affects the expression of the ALOX5AP gene in patients with IS.

Regulation of the Autonomic Nervous System on Intestine.

Intestine is composed of various types of cells including absorptive epithelial cells, goblet cells, endocrine cells, Paneth cells, immunological cells, and so on, which play digestion, absorption, neuroendocrine, immunological function. Intestine is innervated with extrinsic autonomic nerves and intrinsic enteric nerves. The neurotransmitters and counterpart receptors are widely distributed in the different intestinal cells. Intestinal autonomic nerve system includes sympathetic and parasympathetic nervous systems, which regulate cellular proliferation and function in intestine under physiological and pathophysiological conditions. Presently, distribution and functional characteristics of autonomic nervous system in intestine were reviewed. How autonomic nervous system regulates intestinal cell proliferation was discussed. Function of autonomic nervous system on intestinal diseases was extensively reviewed. It might be helpful to properly manipulate autonomic nervous system during treating different intestinal diseases.

Association Study Between Genetic Variation in Whole Mitochondrial Genome and Ischemic Stroke.

Mitochondrial DNA (mtDNA) affects the mitochondrial function, which is potentially related to susceptibility to ischemic stroke (IS). However, study on IS genetics by whole mitochondrial genome sequencing has not been extensively explored. Therefore, a two-stage study was designed to explore the relationship between the whole mitochondrial genome variants and IS. In the first stage, whole mitochondrial genomes of 52 IS patients and 55 controls were sequenced by next-generation sequencing. Fifty-three mtDNA mutation sites which may be related to the pathogenesis of IS were discovered. Nine unreported mtDNA variation sites were found for the first time. In the second larger Chinese cohort, we confirmed that m.T195C and m.T12338C in the mitochondrial D-loop region were the protective factors of IS, especially m.T195C and m.C311T in the LAA subtype. In conclusion, our study provided population genetic information and a reference for IS-relevant research, with wide applications in diagnosis, therapeutic treatments and prediction of IS.

Molecular Modulation of Fetal Liver Hematopoietic Stem Cell Mobilization into Fetal Bone Marrow in Mice.

Development of hematopoietic stem cells is a complex process, which has been extensively investigated. Hematopoietic stem cells (HSCs) in mouse fetal liver are highly expanded to prepare for mobilization of HSCs into the fetal bone marrow. It is not completely known how the fetal liver niche regulates HSC expansion without loss of self-renewal ability. We reviewed current progress about the effects of fetal liver niche, chemokine, cytokine, and signaling pathways on HSC self-renewal, proliferation, and expansion. We discussed the molecular regulations of fetal HSC expansion in mouse and zebrafish. It is also unknown how HSCs from the fetal liver mobilize, circulate, and reside into the fetal bone marrow niche. We reviewed how extrinsic and intrinsic factors regulate mobilization of fetal liver HSCs into the fetal bone marrow, which provides tools to improve HSC engraftment efficiency during HSC transplantation. Understanding the regulation of fetal liver HSC mobilization into the fetal bone marrow will help us to design proper clinical therapeutic protocol for disease treatment like leukemia during pregnancy. We prospect that fetal cells, including hepatocytes and endothelial and hematopoietic cells, might regulate fetal liver HSC expansion. Components from vascular endothelial cells and bones might also modulate the lodging of fetal liver HSCs into the bone marrow. The current review holds great potential to deeply understand the molecular regulations of HSCs in the fetal liver and bone marrow in mammals, which will be helpful to efficiently expand HSCs in vitro.

A Promoter Polymorphism (Rs57137919) of ABCG1 Gene Influence on Blood Lipoprotein in Chinese Han Population.

BACKGROUND: Adenosine triphosphate-binding cassette subfamily G member 1 (ABCG1) has the function of transporting free intracellular cholesterol to extracellular high-density lipoprotein (HDL) particles, which play a crucial role in atherosclerosis. The goal of this study is to examine the relationship between the polymorphisms of the ABCG1 gene promoter region and ischemic stroke. METHODS: In the present study, a case-control association study was designed to identify 3 single-nucleotide polymorphisms (SNPs; rs5713919, rs1378577, and rs1893590), which were located in the promoter region of ABCG1 gene by kompetitive allele-specific polymerase chain reaction genotyping approach. The in vitro luciferase assay was done to estimate the effect of rs5713919 on gene expression. Finally, the relationships of 3 SNPs of ABCG1 gene with plasma lipids and lipoproteins were investigated in this Chinese cohort. RESULTS: The correlation analysis between lipids and genotypes showed that the rs57137919 locus genotype was significantly associated with HDL cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels (P = 0.021 and P = 0.017, respectively), and the GA and AA genotypes had higher HDL-C levels than the GG genotype. CONCLUSIONS: Our study provides evidence that ABCG1 promoter region polymorphism rs57137919 has an influence on plasma HDL-C and LDL-C levels in Chinese Han population.

A c.544_618del75bp mutation in the splicing factor gene PRPF31 is involved in non-syndromic retinitis pigmentosa by reducing the level of mRNA expression.

PURPOSE: A previous study reported a novel c.544_618del75bp mutation in exon 7 of the PRPF31 gene in a Chinese family with autosomal dominant retinal pigmentosa (ADRP). However, the selected pedigree was a small part of the whole family and the function of the c.544_618del75bp mutation was not explored deeply. The aim of the present study was to validate the previous results and explore the functional significance of the c.544_618del75bp mutation. METHODS: We extended the size of the ADRP pedigree and sequenced DNA and cDNA of the PRPF31 gene for all members of the family and 100 healthy controls. Real-time quantitative polymerase chain reaction (PCR) analysis was performed on the cDNA of patients in the family and cell culture, plasmids transfection and western blot analysis were done to evaluate the functional effect of the mutation in vitro. RESULTS: Sanger sequencing showed that the mutation was present in all patients and absent in all normal individuals, except for participant III-9. Bioinformatics analysis revealed that the c.544_618del75bp mutation caused a 25 amino acid deletion in the PRPF31 protein. In addition, the mRNA expression assay revealed that the mRNA expression level of the PRPF31 and RP9 genes were significantly lower in RP patients than controls (p < 0.05). Finally, the in vitro transfection assay demonstrated that the mRNA expression level of the mutant transfection group was significantly lower than the wild-type transfection group (p < 0.05). CONCLUSIONS: Our study suggested that the c.544_618del75bp mutation in the PRPF31 gene was a causative mutation in this ADRP family and affected the expression of RP9 gene by influencing the formation of U4/U6-U5 tri-snRNP, eventually leading to the occurrence of RP.