GDF1 ameliorates cognitive impairment induced by hearing loss.

Hearing loss is associated with an increased risk of Alzheimer disease (AD). However, the mechanisms of hearing loss promoting the onset of AD are poorly understood. Here we show that hearing loss aggravates cognitive impairment in both wild-type mice and mouse models of AD. Embryonic growth/differentiation factor 1 (GDF1) is downregulated in the hippocampus of deaf mice. Knockdown of GDF1 mimics the detrimental effect of hearing loss on cognition, while overexpression of GDF1 in the hippocampus attenuates the cognitive impairment induced by deafness. Strikingly, overexpression of GDF1 also attenuates cognitive impairment in APP/PS1 transgenic mice. GDF1 activates Akt, which phosphorylates asparagine endopeptidase and inhibits asparagine endopeptidase-induced synaptic degeneration and amyloid-ß production. The expression of GDF1 is downregulated by the transcription factor CCAAT-enhancer binding protein-ß. These findings indicate that hearing loss could promote AD pathological changes by inhibiting the GDF1 signaling pathway; thus, GDF1 may represent a therapeutic target for AD.

Growth differentiation factor 1-induced tumour plasticity provides a therapeutic window for immunotherapy in hepatocellular carcinoma.

Tumour lineage plasticity is an emerging hallmark of aggressive tumours. Tumour cells usually hijack developmental signalling pathways to gain cellular plasticity and evade therapeutic targeting. In the present study, the secreted protein growth and differentiation factor 1 (GDF1) is found to be closely associated with poor tumour differentiation. Overexpression of GDF1 suppresses cell proliferation but strongly enhances tumour dissemination and metastasis. Ectopic expression of GDF1 can induce the dedifferentiation of hepatocellular carcinoma (HCC) cells into their ancestral lineages and reactivate a broad panel of cancer testis antigens (CTAs), which further stimulate the immunogenicity of HCC cells to immune-based therapies. Mechanistic studies reveal that GDF1 functions through the Activin receptor-like kinase 7 (ALK7)-Mothers against decapentaplegic homolog 2/3 (SMAD2/3) signalling cascade and suppresses the epigenetic regulator Lysine specific demethylase 1 (LSD1) to boost CTA expression. GDF1-induced tumour lineage plasticity might be an Achilles heel for HCC immunotherapy. Inhibition of LSD1 based on GDF1 biomarker prescreening might widen the therapeutic window for immune checkpoint inhibitors in the clinic.

Association of functional variant in GDF1 promoter with risk of congenital heart disease and its regulation by Nkx2.5.

GDF1 plays an important role in left-right patterning and genetic mutations in the coding region of GDF1 are associated with congenital heart disease (CHD). However, the genetic variation in the promoter of GDF1 with sporadic CHD and its expression regulation is little known. The association of the genetic variation in GDF1 promoter with CHD was examined in two case-control studies, including 1084 cases and 1198 controls in the first study and 582 cases and 615 controls in the second study. We identified one single nucleotide polymorphism (SNP) rs181317402 and two novel genetic mutations located in the promoter region of GDF1. Analysis of combined samples revealed a significant association in genotype and allele frequencies of rs181317402 T/G polymorphism between CHD cases in overall or ventricular septal defects or Tetralogy of Fallot and the control group. rs181317402 allele G polymorphism was significantly associated with a decreased risk of CHD. Furthermore, luciferase assay, chromatin immunoprecipitation and DNA pulldown assay indicated that Nkx2.5 transactivated the expression of GDF1 by binding to the promoter of GDF1. Luciferase activity assay showed that rs181317402 allele G significantly increased the basal and Nkx2.5-mediated activity of GDF1 promoter, while the two genetic mutations had the opposite effect. rs181317402 TG genotype was associated with significantly increased mRNA level of GDF1 compared with TT genotype in 18 CHD individuals. Our results demonstrate for the first time that Nkx2.5 acts upstream of GDF1 and the genetic variants in GDF1 promoter may confer genetic susceptibility to sporadic CHD potentially by altering its expression.

Cardioprotective role of growth/differentiation factor 1 in post-infarction left ventricular remodelling and dysfunction.

Growth/differentiation factor 1 (GDF1) is a secreted glycoprotein of the transforming growth factor-ß (TGF-ß) superfamily that mediates cell differentiation events during embryonic development. GDF1 is expressed in several tissues, including the heart. However, the functional role of GDF1 in myocardial infarction (MI)-induced cardiac remodelling and dysfunction is not known. Here, we performed gain-of-function and loss-of-function studies using cardiac-specific GDF1 transgenic (TG) and knockout (KO) mice to determine the role of GDF1 in the pathogenesis of functional and architectural cardiac remodelling after MI, which was induced by surgical left anterior descending coronary artery ligation. Our results demonstrate that overexpression of GDF1 in the heart causes a significant decrease in MI-derived mortality post-MI and leads to attenuated infarct size expansion, left ventricular (LV) dilatation, and cardiac dysfunction at 1 week and 4 weeks after MI injury. Compared with control animals, cardiomyocyte apoptosis, inflammation, hypertrophy, and interstitial fibrosis were all remarkably reduced in the GDF1-TG mice following MI. In contrast, GDF1 deficiency greatly exacerbated the pathological cardiac remodelling response after infarction. Further analysis of the in vitro and in vivo signalling events indicated that the beneficial role of GDF1 in MI-induced cardiac dysfunction and LV remodelling was associated with the inhibition of non-canonical (MEK-ERK1/2) and canonical (Smad) signalling cascades. Overall, our data reveal that GDF1 in the heart is a novel mediator that protects against the development of post-infarction cardiac remodelling via negative regulation of the MEK-ERK1/2 and Smad signalling pathways. Thus, GDF1 may serve as a valuable therapeutic target for the treatment of MI.

Nature and extent of left/right axis defects in T(Wis) /T(Wis) mutant mouse embryos.

BACKGROUND: Mutations in the T-box gene Brachyury have well known effects on invagination of the endomesodermal layer during gastrulation, but the gene also plays a role in the determination of left/right axis determination that is less well studied. Previous work has implicated node morphology in this effect. We use the T(Wis) allele of Brachyury to investigate the molecular and morphological effects of the T locus on axis determination in the mouse. RESULTS: Similar to embryos mutant for the T allele, T(Wis) /T(Wis) embryos have a high incidence of ventral and/or reversed heart looping. In addition, heterotaxia between the direction of heart looping and the direction of embryo turning is common. Scanning electron microscopy reveals defects in node morphology including irregularity, smaller size, and a decreased number of cilia, although the cilia appear morphologically normal. Molecular analysis shows a loss of perinodal expression of genes involved in Nodal signaling, namely Cer2, Gdf1, and Nodal itself. There is also loss of Dll1 expression, a key component of the Notch signaling pathway, in the presomitic mesoderm. CONCLUSIONS: Morphological abnormalities of the node as well as disruptions of the molecular cascade of left/right axis determination characterize T(Wis) /T(Wis) mutants. Decreased Notch signaling may account for both the morphological defects and the absence of expression of genes in the Nodal signaling pathway.

Nodal·Gdf1 heterodimers with bound prodomains enable serum-independent nodal signaling and endoderm differentiation.

The TGFß family member Nodal is central to control pluripotent stem cell fate, but its use as a stem cell differentiation factor is limited by low specific activity. During development, Nodal depends on growth and differentiation factor (Gdf)-1 and on the shared co-receptor Cryptic to specify visceral left-right axis asymmetry. We therefore asked whether the functionality of Nodal can be augmented by Gdf1. Because Nodal and Gdf1 coimmunoprecipitate each other, they were predicted to form heterodimers, possibly to facilitate diffusion or to increase the affinity for signaling receptors. Here, we report that Gdf1 suppresses an unexpected dependence of Nodal on serum proteins and that it is critically required for non-autonomous signaling in cells expressing Cryptic. Nodal, Gdf1, and their cleaved propeptides copurified as a heterodimeric low molecular weight complex that stimulated Activin receptor (Acvr) signaling far more potently than Nodal alone. Although heterodimerization with Gdf1 did not increase binding of Nodal to Fc fusions of co-receptors or Acvr extracellular domains, it was essential for soluble Acvr2 to inhibit Nodal signaling. This implies that Gdf1 potentiates Nodal activity by stabilizing a low molecular weight fraction that is susceptible to neutralization by soluble Acvr2. Finally, in differentiating human ES cells, endodermal markers were more efficiently induced by Nodal·Gdf1 than by Nodal, suggesting that Nodal·Gdf1 is an attractive new reagent to direct stem cell differentiation.

Growth/differentiation factor 1 alleviates pressure overload-induced cardiac hypertrophy and dysfunction.

Pathological cardiac hypertrophy is a major risk factor for developing heart failure, the leading cause of death in the world. Growth/differentiation factor 1 (GDF1), a transforming growth factor-ß family member, is a regulator of cell growth and differentiation in both embryonic and adult tissues. Evidence from human and animal studies suggests that GDF1 may play an important role in cardiac physiology and pathology. However, a critical role for GDF1 in cardiac remodelling has not been investigated. Here, we performed gain-of-function and loss-of-function studies using cardiac-specific GDF1 knockout mice and transgenic mice to determine the role of GDF1 in pathological cardiac hypertrophy, which was induced by aortic banding (AB). The extent of cardiac hypertrophy was evaluated by echocardiographic, hemodynamic, pathological, and molecular analyses. Our results demonstrated that cardiac specific GDF1 overexpression in the heart markedly attenuated cardiac hypertrophy, fibrosis, and cardiac dysfunction, whereas loss of GDF1 in cardiomyocytes exaggerated the pathological cardiac hypertrophy and dysfunction in response to pressure overload. Mechanistically, we revealed that the cardioprotective effect of GDF1 on cardiac remodeling was associated with the inhibition of the MEK-ERK1/2 and Smad signaling cascades. Collectively, our data suggest that GDF1 plays a protective role in cardiac remodeling via the negative regulation of the MEK-ERK1/2 and Smad signaling pathways.

Gata2 provides an early anterior bias and uncovers a global positioning system for polarity in the amniote embryo.

The first axis to be specified during vertebrate development is that between the site where gastrulation will begin and the opposite pole of the embryo (dorsoventral axis in amphibians and fish, anteroposterior in amniotes). This relies on Nodal activity, but different vertebrates differ in how this activity is positioned. In chick, the earliest known asymmetry is posterior expression of the TGFß-related factor Vg1, close to the future Nodal expression domain. Here we show that the transcription factor Gata2 is expressed anteriorly before this stage. Gata2 influences the site of primitive streak formation and its role is independent from, and upstream of, Vg1 and Wnt. However, although Vg1 is required for streak formation, Gata2 does not act as an absolute anterior specifier, but provides an anterior bias. These findings point to previously unsuspected global determinants of polarity of the early amniote embryo.