Project description:Astrocyte maldevelopment is implicated in various neuropsychiatric diseases associated with early life stress. However, the underlying astrocytopathy mechanism, which can result in the psychiatric symptoms, remains unclear. In this study, it is shown that a reduced oligodendrocyte precursor cell (OPC) population accompanies hindered hippocampal astrocytic development in an improved parental isolation mouse model, and that the loss of OPCs suppresses astrocytic network formation and activity. It is further demonstrated that OPC-derived Wnt ligands, in particular Wnt7b, are required for Wnt/β-catenin pathway-mediated astrocytic development and subsequent effects related to neuronal function. In addition, focal replenishment of Wnt7a/b is sufficient to rescue astrocytic maldevelopment. These results elucidate a Wnt-paracrine-dependent but myelin-independent role of OPCs in regulating astrocytic development, which provides a unique insight into the astrocytopathy mechanism in early life stress, and can be implicated in the pathogenesis of human early life stress-related neuropsychiatric disorders.
Project description:Among dendritic cell (DC) subsets, CD8alpha(+) DCs and plasmacytoid DCs (pDCs) produce high levels of IL12 and type I interferons (IFNs), respectively, and confer early innate immunity. Development of CD8alpha(+) DCs and pDCs requires the interferon regulatory factor 8 (IRF8). Recently, a spontaneous point mutation was identified in the Irf8/Icsbp gene in the BXH2 mouse, which exhibits an immunodeficient phenotype similar to the IRF8 knockout (KO) mouse. We show that this mutation, designated IRF8(R294C), abolishes the development of CD8alpha(+) DCs without impairing pDC development, and eliminates production of IL12p40, while retaining that of type I IFNs. Electrophoretic mobility shift and chromatin immunoprecipitation assays indicated that IRF8(R294C) failed to interact with partner transcription factors and did not bind certain promoters that require partner interactions. Together, this work indicates that IRF8-partner interactions play different roles in CD8alpha(+) DCs and pDCs, revealing a mechanistic separation that underlies development of these DC subsets.
Project description:Common variable immunodeficiency (CVID) is a disease characterized by increased susceptibility to infections, hypogammaglobulinemia, and immune dysregulation. Although CVID is thought to be a disorder of the peripheral B-cell compartment, in 25% of patients, early B-cell development in the bone marrow is impaired. Because poor B-cell reconstitution after hematopoietic stem cell transplantation has been observed, we hypothesized that in some patients the bone marrow environment is not permissive to B-cell development. Studying the differentiation dynamics of bone marrow-derived CD34+ cells into immature B cells in vitro allowed us to distinguish patients with B-cell intrinsic defects and patients with a nonpermissive bone marrow environment. In the former, immature B cells did not develop and in the latter CD34+ cells differentiated into immature cells in vitro, but less efficiently in vivo. In a further group of patients, the uncommitted precursors were unable to support the constant development of B cells in vitro, indicating a possible low frequency or exhaustion of the precursor population. Hematopoietic stem cell transplantation would result in normal B-cell repopulation in case of intrinsic B-cell defect, but in defective B-cell repopulation in a nonpermissive environment. Our study points to the importance of the bone marrow niche in the pathogenesis of CVID.
Project description:Preclinical and clinical evidence implicates N-methyl-d-aspartate receptor (NMDAr) signaling in early embryological development. However, the role of NMDAr signaling in early development has not been well studied. Here, we use a mouse embryonic stem cell model to perform a step-wise exploration of the effects of NMDAr signaling on early cell fate specification. We found that antagonism of the NMDAr impaired specification into the neuroectodermal and mesoendodermal cell lineages, with little or no effect on specification of the extraembryonic endoderm cell lineage. Consistent with these findings, exogenous NMDA promoted neuroectodermal differentiation. Finally, NMDAr antagonism modified expression of several key targets of TGF-β superfamily signaling, suggesting a mechanism for these findings. In summary, this study shows that NMDAr antagonism interferes with the normal developmental pathways of embryogenesis, and suggests that interference is most pronounced prior to neuroectodermal and mesoendodermal cell fate specification.
Project description:Topotecan is a topoisomerase 1 (TOP1) inhibitor that is used to treat various forms of cancer. We recently found that topotecan reduces the expression of multiple long genes, including many neuronal genes linked to synapses and autism. However, whether topotecan alters synaptic protein levels and synapse function is currently unknown. Here we report that in primary cortical neurons, topotecan depleted synaptic proteins that are encoded by extremely long genes, including Neurexin-1, Neuroligin-1, Cntnap2, and GABA(A)β3. Topotecan also suppressed spontaneous network activity without affecting resting membrane potential, action potential threshold, or neuron health. Topotecan strongly suppressed inhibitory neurotransmission via pre- and postsynaptic mechanisms and reduced excitatory neurotransmission. The effects on synaptic protein levels and inhibitory neurotransmission were fully reversible upon drug washout. Collectively, our findings suggest that TOP1 controls the levels of multiple synaptic proteins and is required for normal excitatory and inhibitory synaptic transmission.
Project description:m6A is one of the most common and abundant modifications of RNA molecules present in eukaryotes. The methyltransferase complex, consisting of methyltransferase-like 3 (METTL3), METTL14, and WTAP, is responsible for the m6A modification of RNA. WTAP was identified as an mRNA splicing regulator. Its role as a regulatory subunit of the m6A methyltransferase complex in embryonic development remains largely unknown. To investigate the role of WTAP in porcine early embryonic development, si-WTAP was microinjected into porcine parthenogenetic zygotes. WTAP knockdown significantly reduced the blastocyst rate and global m6A levels, but did not affect the cleavage rate. Betaine was supplemented into the in vitro culture (IVC) to increase the m6A levels. Betaine significantly increased the global m6A levels but did not affect the blastocyst rate. Furthermore, the pluripotency genes, including OCT4, SOX2, and NANOG, were downregulated following WTAP knockdown. The apoptotic genes BAX and CASPASE 3 were upregulated, while the anti-apoptotic gene BCL2 was downregulated in WTAP knockdown blastocysts. TUNEL staining revealed that the number of apoptotic cells was significantly increased following WTAP knockdown. Our study indicated that WTAP has an indispensable role in porcine early embryonic development.
Project description:NKp46 (CD335) is a surface receptor shared by both human and mouse natural killer (NK) cells and innate lymphoid cells (ILCs) that transduces activating signals necessary to eliminate virus-infected cells and tumors. Here, we describe a spontaneous point mutation of cysteine to arginine (C14R) in the signal peptide of the NKp46 protein in congenic Ly5.1 mice and the newly generated NCRB6C14R strain. Ly5.1C14R NK cells expressed similar levels of Ncr1 mRNA as C57BL/6, but showed impaired surface NKp46 and reduced ability to control melanoma tumors in vivo. Expression of the mutant NKp46C14R in 293T cells showed that NKp46 protein trafficking to the cell surface was compromised. Although Ly5.1C14R mice had normal number of NK cells, they showed an increased number of early maturation stage NK cells. CD49a+ILC1s were also increased but these cells lacked the expression of TRAIL. ILC3s that expressed NKp46 were not detectable and were not apparent when examined by T-bet expression. Thus, the C14R mutation reveals that NKp46 is important for NK cell and ILC differentiation, maturation and function. Significance Innate lymphoid cells (ILCs) play important roles in immune protection. Various subsets of ILCs express the activating receptor NKp46 which is capable of recognizing pathogen derived and tumor ligands and is necessary for immune protection. Here, we describe a spontaneous point mutation in the signal peptide of the NKp46 protein in congenic Ly5.1 mice which are widely used for tracking cells in vivo. This Ncr1 C14R mutation impairs NKp46 surface expression resulting in destabilization of Ncr1 and accumulation of NKp46 in the endoplasmic reticulum. Loss of stable NKp46 expression impaired the maturation of NKp46+ ILCs and altered the expression of TRAIL and T-bet in ILC1 and ILC3, respectively.
Project description:Mitochondrial reactive oxygen species (ROS) are proposed to play a central role in aging and age-associated disorders, although direct in vivo evidence is lacking. We recently generated a mouse mutant with mutated inner mitochondrial membrane peptidase 2-like (Immp2l) gene, which impairs the signal peptide sequence processing of mitochondrial proteins cytochrome c1 and glycerol phosphate dehydrogenase 2. The mitochondria from mutant mice generate elevated levels of superoxide ion and cause impaired fertility in both sexes. Here, we design experiments to examine the effects of excessive mitochondrial ROS generation on health span. We show that Immp2l mutation increases oxidative stress in multiple organs such as the brain and the kidney, although expression of superoxide dismutases in these tissues of the mutants is also increased. The mutants show multiple aging-associated phenotypes, including wasting, sarcopenia, loss of subcutaneous fat, kyphosis, and ataxia, with female mutants showing earlier onset and more severe age-associated disorders than male mutants. The loss of body weight and fat was unrelated to food intake. Adipose-derived stromal cells (ADSC) from mutant mice showed impaired proliferation capability, formed significantly less and smaller colonies in colony formation assays, although they retained adipogenic differentiation capability in vitro. This functional impairment was accompanied by increased levels of oxidative stress. Our data showed that mitochondrial ROS is the driving force of accelerated aging and suggested that ROS damage to adult stem cells could be one of the mechanisms for age-associated disorders.
Project description:BACKGROUND:Fetal growth restriction (FGR) is a major risk factor for bronchopulmonary dysplasia (BPD). Maternal stress and poor diet are linked to FGR. Effect of perinatal stress on lung development remains unknown. OBJECTIVE:Using a murine model of adverse early life environment (AELE), we hypothesized that maternal exposure to perinatal environmental stress and high-fat diet (Western diet) lead to impaired lung development in the offspring. METHODS:Female mice were placed on either control diet or Western diet before conception. Those exposed to Western diet were also exposed to perinatal environmental stress, the combination referred to as AELE. Pups were either euthanized at postnatal day 21 (P21) or weaned to control diet and environment until adulthood (8-14 wk old). Lungs were harvested for histology, gene expression by quantitative RT-PCR, microRNA profiling, and immunoblotting. RESULTS:AELE increased the mean linear intercept and decreased the radial alveolar count and secondary septation in P21 and adult mice. Capillary count was also decreased in P21 and adult mice. AELE lungs had decreased vascular endothelial growth factor A (VEGFA), VEGF receptor 2, endothelial nitric oxide synthase, and hypoxia inducible factor-1? protein levels and increased expression of genes that regulate DNA methylation and upregulation of microRNAs that target genes involved in lung development at P21. CONCLUSION:AELE leads to impaired lung alveolar and vascular growth, which persists into adult age despite normalizing the diet and environment at P21. AELE also alters the expression of genes involved in lung remodeling.
Project description:The MAF family transcription factors are homologs of v-Maf, the oncogenic component of the avian retrovirus AS42. They are subdivided into 2 groups, small and large MAF proteins, according to their structure, function, and molecular size. MAFK is a member of the small MAF family and acts as a dominant negative form of large MAFs. In previous research we generated transgenic mice that overexpress MAFK in order to suppress the function of large MAF proteins in pancreatic ?-cells. These mice developed hyperglycemia in adulthood due to impairment of glucose-stimulated insulin secretion. The aim of the current study is to examine the effects of ?-cell-specific Mafk overexpression in endocrine cell development. The developing islets of Mafk-transgenic embryos appeared to be disorganized with an inversion of total numbers of insulin+ and glucagon+ cells due to reduced ?-cell proliferation. Gene expression analysis by quantitative RT-PCR revealed decreased levels of ?-cell-related genes whose expressions are known to be controlled by large MAF proteins. Additionally, these changes were accompanied with a significant increase in key ?-cell transcription factors likely due to compensatory mechanisms that might have been activated in response to the ?-cell loss. Finally, microarray comparison of gene expression profiles between wild-type and transgenic pancreata revealed alteration of some uncharacterized genes including Pcbd1, Fam132a, Cryba2, and Npy, which might play important roles during pancreatic endocrine development. Taken together, these results suggest that Mafk overexpression impairs endocrine development through a regulation of numerous ?-cell-related genes. The microarray analysis provided a unique data set of differentially expressed genes that might contribute to a better understanding of the molecular basis that governs the development and function of endocrine pancreas.