Expression pattern of growth/differentiation factor 3 in human and murine cerebral cortex, hippocampus as well as cerebellum

Identifying genetic risk variants associated with brain volumetric phenotypes via K-sample Ball Divergence method

Regional human brain volumes including total area, average thickness, and total volume are heritable and associated with neurological disorders. However, the genetic architecture of brain structure and function is still largely unknown and worthy of exploring. The Pediatric Imaging, Neurocognition, and Genetics (PING) data set provides an excellent resource with genome-wide genetic data and related neuroimaging data. In this study, we perform genome-wide association studies (GWAS) of 315 brain volumetric phenotypes from the PING data set including 1036 samples with 539,865 single-nucleotide polymorphisms (SNPs). We introduce a nonparametric test based on K-sample Ball Divergence (KBD) to identify genetic risk variants that influence regional brain volumes. We carry out simulations to demonstrate that KBD is a powerful test for identifying significant SNPs associated with multivariate phenotypes although controlling the type I error rate. We successfully identify nine SNPs below a significance level of 5 × 10^-5 for the PING data. Among the nine identified genetic variants, two SNPs rs486179 and rs562110 are located in the ADRA1A gene that is a well-known risk factor of mental illness, such as schizophrenia and attention deficit hyperactivity disorder. Our study suggests that the nonparametric test KBD is an effective method for identifying genetic variants associated with complex diseases in large-scale GWAS of multiple phenotypes.

Administration of GDF3 Into Septic Mice Improves Survival via Enhancing LXRα-Mediated Macrophage Phagocytosis

The defective eradication of invading pathogens is a major cause of death in sepsis. As professional phagocytic cells, macrophages actively engulf/kill microorganisms and play essential roles in innate immune response against pathogens. Growth differentiation factor 3 (GDF3) was previously implicated as an important modulator of inflammatory response upon acute sterile injury. In this study, administration of recombinant GDF3 protein (rGDF3) either before or after CLP surgery remarkably improved mouse survival, along with significant reductions in bacterial load, plasma pro-inflammatory cytokine levels, and organ damage. Notably, our in vitro experiments revealed that rGDF3 treatment substantially promoted macrophage phagocytosis and intracellular killing of bacteria in a dose-dependent manner. Mechanistically, RNA-seq analysis results showed that CD5L, known to be regulated by liver X receptor α (LXRα), was the most significantly upregulated gene in rGDF3-treated macrophages. Furthermore, we observed that rGDF3 could promote LXRα nuclear translocation and thereby, augmented phagocytosis activity in macrophages, which was similar as LXRα agonist GW3965 did. By contrast, pre-treating macrophages with LXRα antagonist GSK2033 abolished beneficial effects of rGDF3 in macrophages. In addition, rGDF3 treatment failed to enhance bacteria uptake and killing in LXRα-knockout (KO) macrophages. Taken together, these results uncover that GDF3 may represent a novel mediator for controlling bacterial infection.

Exploration of the exonic variations of the iPSC-related <i>Nanog</i> gene and their effects on phenotypic traits in cattle

Abstract. Nanog is an important pluripotent transcription regulator transforming somatic cells to induced pluripotent stem cells (iPSCs), and its overexpression leads to a high expression of the growth and differentiation factor 3 (GDF3), which affects animal growth traits. Therefore, the aim of this study was to explore the genetic variations within the Nanog gene and their effects on phenotypic traits in cattle. Six novel exonic single nucleotide polymorphisms (SNPs) were found in six cattle breeds. Seven haplotypes were analyzed: TCAACC (0.260), TCAATA (0.039), TCATCC (0.019), TCGACC (0.506), TCGATA (0.137), TCGTCC (0.036), and CTGATA (0.003). There were strong linkage disequilibriums of SNP1 and SNP2 in Jiaxian cattle as well as of SNP5 and SNP6 in both Jiaxian cattle and Nanyang cattle. Moreover, SNP3, SNP4, and SNP5 were associated with phenotypes. The individuals with GG genotype at the SNP3 locus or AA genotype at the SNP4 locus showed better body slanting length and chest circumference or body height and hucklebone width in Nanyang cattle. The superiority of the SNP5-C allele regarding body height and cannon circumference was observed in Jiaxian cattle. The combination of SNP3 and SNP4 (GG–AA) had positive effects on body height, body slanting length, and chest circumference. These findings may indicate that Nanog, as a regulator of bovine growth traits, could be a candidate gene for marker-assisted selection (MAS) in breeding and genetics in cattle.

Network-driven plasma proteomics expose molecular changes in the Alzheimer's brain

Background

Biological pathways that significantly contribute to sporadic Alzheimer’s disease are largely unknown and cannot be observed directly. Cognitive symptoms appear only decades after the molecular disease onset, further complicating analyses. As a consequence, molecular research is often restricted to late-stage post-mortem studies of brain tissue. However, the disease process is expected to trigger numerous cellular signaling pathways and modulate the local and systemic environment, and resulting changes in secreted signaling molecules carry information about otherwise inaccessible pathological processes.

Results

To access this information we probed relative levels of close to 600 secreted signaling proteins from patients’ blood samples using antibody microarrays and mapped disease-specific molecular networks. Using these networks as seeds we then employed independent genome and transcriptome data sets to corroborate potential pathogenic pathways.

Conclusions

We identified Growth-Differentiation Factor (GDF) signaling as a novel Alzheimer’s disease-relevant pathway supported by in vivo and in vitro follow-up experiments, demonstrating the existence of a highly informative link between cellular pathology and changes in circulatory signaling proteins.

Electronic supplementary material

The online version of this article (doi:10.1186/s13024-016-0095-2) contains supplementary material, which is available to authorized users.

Growth differentiation factor 3 is induced by bone morphogenetic protein 6 (BMP-6) and BMP-7 and increases luteinizing hormone receptor messenger RNA expression in human granulosa cells

OBJECTIVE

To examine the relevance of growth differentiation factor 3 (GDF-3) and bone morphogenetic protein (BMP) cytokines in human ovary.

DESIGN

Molecular studies.

SETTING

Research laboratory.

PATIENT(S)

Eight women undergoing salpingo-oophorectomy and 30 women undergoing ovarian stimulation for in vitro fertilization.

INTERVENTION(S)

Localizing GDF-3 protein in human ovaries; granulosa cells (GC) cultured with GDF-3, BMP-6, or BMP-7 followed by RNA extraction.

MAIN OUTCOME MEASURE(S)

The localization of GDF-3 protein in normal human ovaries via immunohistochemical analysis, GDF-3 messenger RNA (mRNA) expression evaluation via quantitative real-time reverse transcription and polymerase chain reaction (RT-PCR), and evaluation of the effect of GDF-3 on leuteinizing hormone (LH) receptor mRNA expression via quantitative real-time RT-PCR.

RESULT(S)

In the ovary, BMP cytokines, of the transforming growth factor beta (TGF-β) superfamily, are known as a luteinization inhibitor by suppressing LH receptor expression in GC. Growth differentiation factor 3, a TGF-β superfamily cytokine, is recognized as an inhibitor of BMP cytokines in other cells. Immunohistochemical analysis showed that GDF-3 was strongly detected in the GC of antral follicles. An in vitro assay revealed that BMP-6 or BMP-7 induced GDF-3 mRNA in GC. Also, GDF-3 increased LH receptor mRNA expression and inhibited the effect of BMP-7, which suppressed the LH receptor mRNA expression in GC.

CONCLUSION(S)

GDF-3, induced with BMP-6 and BMP-7, might play a role in folliculogenesis by inhibiting the effect of BMP cytokines.

The conditioned medium from a stable human GDF3-expressing CHO cell line, induces the differentiation of PC12 cells

Members of the transforming growth factor-β (TGF-β) superfamily have significant roles in the regulation of a wide variety of physiological processes. In our present work, phylogenetic tree analysis showed that human GDF3 (Growth and differentiation factor 3) and human GDF1 formed a subgroup of closely related molecules. Through quantitative real-time PCR analysis in different human tissues, GDF1 and GDF3 expression level had a big difference in brain. GDF3 could activate downstream signaling through associating with ALK7 (Activin receptor-like kinase 7) in a Cripto-dependent fashion. A CHO cell line stably transfected with the encoding sequence of GDF3, named CHO-GDF3, was established. Western blotting analysis demonstrated that GDF3 protein could be secreted into the medium from CHO cells and immunofluorescence experiment showed that GDF3 was mainly distributed in cytoplasm of the stable cell line, the primary hippocampal neurons, and brain tissues. Furthermore, the conditioned medium from CHO-GDF3 could reduce PC12 cell growth and induce cell differentiation. All these findings bring new insights into the functional study of GDF3.

Markers of pluripotency and differentiation in human neural precursor cells derived from embryonic stem cells and CNS tissue

Cell transplantation therapies for central nervous system (CNS) deficits such as spinal cord injury (SCI) have been shown to be effective in several animal models. One cell type that has been transplanted is neural precursor cells (NPCs), for which there are several possible sources. We have studied NPCs derived from human embryonic stem cells (hESCs) and human fetal CNS tissue (hfNPCs), cultured as neurospheres, and the expression of pluripotency and neural genes during neural induction and in vitro differentiation. mRNA for the pluripotency markers Nanog, Oct-4, Gdf3, and DNMT3b were downregulated during neural differentiation of hESCs. mRNA for these markers was found in nonpluripotent hfNPC at higher levels compared to hESC-NPCs. However, Oct-4 protein was found in hESC-NPCs after 8 weeks of culture, but not in hfNPCs. Similarly, SSEA-4 and CD326 were only found in hESC-NPCs. NPCs from both sources differentiated as expected to cells with typical features of neurons and astrocytes. The expressions of neuronal markers in hESC-NPCs were affected by the composition of cell culture medium, while this did not affect hfNPCs. Transplantation of hESC-NPC or hfNPC neurospheres into immunodeficient mouse testis or subcutaneous tissue did not result in tumor formation. In contrast, typical teratomas appeared in all animals after transplantation of hESC-NPCs to injured or noninjured spinal cords of immunodeficient rats. Our data show that transplantation to the subcutaneous tissue or the testes of immunodeficient mice is not a reliable method for evaluation of the tumor risk of remaining pluripotent cells in grafts.

Generation and characterization of a Gdf1 conditional null allele

Growth differentiation factor-1 (GDF1), a TGF-beta superfamily member, participates in early embryo patterning. Later functions are implied by the Gdf1 expression in the peripheral and central nervous system. Such roles of the gene have been difficult to study, because Gdf1 null mice die during late embryogenesis. Here, we report the production of a mouse carrying a conditional Gdf1 allele, with exon 2 flanked by loxP sites. Crossing these mice with CaMKIIalpha-Cre mice resulted in Gdf1 ablation in the forebrain postnatally. Such mice displayed no behavioral changes or altered expression levels in a set of hippocampal genes examined. However, excision of the floxed Gdf1 exon caused increased expression of the remaining part of the bicistronic Uog1-Gdf1 transcript in the hippocampus. This indicates that the transcript level is regulated by a negative feedback-loop, sensing presence of either the protein or the mRNA region encoded by Gdf1 exon 2.