The role of GDF11 during inflammation – An overview

GDF11 promotes osteogenic/odontogenic differentiation of dental pulp stem cells to accelerate dentin restoration via modulating SIRT3/FOXO3-mediated mitophagy

BACKGROUND

Growth differentiation factor 11 (GDF11) is considered to be a potential molecular target for treating pulpitis. However, whether GDF11 regulates osteogenic/odontogenic differentiation of dental pulp stem cells (DPSCs) to mediate pulpitis process remains unclear.

METHODS

Lipopolysaccharide (LPS) was used to induce inflammation conditions in DPSCs. The levels of GDF11, sirtuin 3 (SIRT3), forkhead box O-3 (FOXO3), osteogenic/odontogenic differentiation-related markers were measured by quantitative real-time PCR (qRT-PCR) and western blot (WB). Immunofluorescence staining was used to measure mitophagy. Mitophagy-related proteins were analyzed by WB, and the levels of inflammation factors were examined using qRT-PCR, ELISA and immunohistochemistry. Alkaline phosphatase activity and alizarin red S intensity were evaluated to assess osteogenic differentiation. Acute pulp (AP) injury rat model was constructed to study the role of oe-GDF11 in vivo.

RESULTS

GDF11 was downregulated in LPS-induced DPSCs, and LPS suppressed osteogenic/odontogenic differentiation and mitophagy. GDF11 overexpression promoted osteogenic/odontogenic differentiation in DPSCs through the activation of mitophagy. Furthermore, GDF11 upregulated SIRT3 to enhance FOXO3 expression by inhibiting its acetylation. GDF11 ameliorated LPS-induced inflammation and promoted osteogenic/odontogenic differentiation in DPSCs via enhancing SIRT3/FOXO3-mediated mitophagy. Besides, GDF11 overexpression suppressed inflammation and promoted dentin repair in AP rat models.

CONCLUSION

GDF11 promoted SIRT3/FOXO3-mediated mitophagy to accelerate osteogenic/odontogenic differentiation in DPSCs, providing a novel target for pulpitis treatment.

Hallmarks of uterine receptivity predate placental mammals

Embryo implantation requires tightly coordinated signaling between the blastocyst and the endometrium, and is crucial for the establishment of a uteroplacental unit that persists until term in eutherian mammals. In contrast, marsupials, with a unique life cycle and short gestation, make only brief fetal-maternal contact and lack implantation. To better understand the evolutionary link between eutherian implantation and its ancestral equivalent in marsupials, we compare single-cell transcriptomes from the receptive and non-receptive endometrium of the mouse and guinea pig with that of the opossum, a marsupial. We identify substantial differences between rodent peri-implantation endometrium and opossum placental attachment, including differences in the diversity and abundance of stromal and epithelial cells which parallel the difference between histotrophic and hemotrophic provisioning strategies. We also identify a window of conserved epithelial gene expression between the opossum shelled blastocyst stage and rodent peri-implantation, including IHH and LIF . We find strong conservation of blastocyst proteases, steroid synthetases, Wnt and BMP signals between eutherians and the opossum despite its lack of implantation. Finally, we show that the signaling repertoire of the maternal uterine epithelium during implantation displays substantial overlap with that of the post-implantation placental trophoblast, suggesting that the fetal trophoblast can compensate for the loss of endometrial epithelium in eutherian invasive placentation. Together, our results suggest that eutherian implantation primarily involved the re-wiring of maternal signaling networks, some of which were already present in the therian ancestor, and points towards an essential role of maternal innovations in the evolution of invasive placentation.

GDF11 improves hippocampal neurogenesis and cognitive abilities in diabetic mice by reducing neural inflammation

BACKGROUND

The cognitive decline associated with type 2 diabetes (T2D) is often attributed to compromised hippocampal neurogenesis and exacerbated neural inflammation. This study investigates the therapeutic potential of growth differentiation factor 11 (GDF11) in reversing these neurodegenerative processes in diabetic mice.

RESULT

We utilized a murine model of T2D and examined the effects of GDF11 on learning, memory, neurogenesis, and neuroinflammatory markers. Our results indicate that diabetic mice exhibit significant deficits in cognitive function, mirrored by reduced hippocampal neurogenesis and increased neuroinflammation. Chronic administration of GDF11 was observed to significantly enhance cognitive abilities, as evidenced by improved performance in learning and memory tasks. Concurrently, GDF11 treatment restored neural activity and promoted the regeneration of new neurons within the hippocampus. Inflammatory profiling revealed a reduction in neuroinflammatory markers, which was further supported by reduced microglia numbers. To delineate the role of neuroinflammation, we pharmacologically depleted microglia, leading to a restoration of neurogenesis and cognitive functions in diabetic mice.

CONCLUSION

These findings endorse the hypothesis that GDF11 exerts its beneficial effects by modulating neuroinflammatory pathways. Consequently, GDF11 represents a promising intervention to ameliorate diabetes-induced cognitive impairments and neural degeneration through its anti-inflammatory properties.

Growth differentiation factor-11 upregulates matrix metalloproteinase 2 expression by inducing Snail in human extravillous trophoblast cells

The human extravillous trophoblast (EVT) cell invasion is an important process during placentation. Although the placenta is normal tissue, the EVT cells exhibit some features common to cancer cells, including high migratory and invasive properties. Snail and Slug are transcription factors that mediate the epithelial-mesenchymal transition (EMT), a crucial event for cancer cell migration and invasion. It has been shown that GDF-11-induced matrix metalloproteinase 2 (MMP2) expression is required for EVT cell invasion. Whether GDF-11 can regulate Snail and Slug expression in human EVT cells remains unknown. If it does, the involvement of Snail and Slug in GDF-11-induced MMP2 expression and EVT cell invasion must also be defined. In the present study, using the immortalized human EVT cell line, HTR-8/SVneo, and primary cultures of human EVT cells as experimental models, our results show that GDF-11 upregulates Snail and Slug expression. ALK4 and ALK5 mediate the stimulatory effects of GDF-11 on Snail and Slug expression. In addition, we demonstrate that SMAD2 and SMAD3 are required for the GDF-11-upregulated Snail expression, while only SMAD3 is involved in GDF-11-induced Slug expression. Moreover, our results reveal that Snail mediates GDF-11-induced MMP2 expression and cell invasion but not Slug. This study increases our understanding of the biological function of GDF-11 in human EVT cells and provides a novel mechanism for regulating MMP2 and EVT cell invasion.

Tissue Expression of Growth Differentiation Factor 11 in Patients with Breast Cancer

Protein growth differentiation factor 11 (GDF11) plays crucial roles in cellular processes, including differentiation and development; however, its clinical relevance in breast cancer patients is poorly understood. We enrolled 68 breast cancer patients who underwent surgery at our hospital and assessed the expression of GDF11 in tumorous, ductal carcinoma in situ (DCIS), and non-tumorous tissues using immunohistochemical staining, with interpretation based on histochemical scoring (H-score). Our results indicated higher GDF11 expressions in DCIS and normal tissues compared to tumorous tissues. In addition, the GDF11 H-score was lower in the patients with a tumor size ≥ 2 cm, pathologic T3 + T4 stages, AJCC III-IV stages, Ki67 ≥ 14% status, HER2-negative, and specific molecular tumor subtypes. Notably, the patients with triple-negative breast cancer exhibited a loss of GDF11 expression. Spearman correlation analysis revealed associations between GDF11 expression and various clinicopathological characteristics, including tumor size, stage, Ki67, and molecular subtypes. Furthermore, GDF11 expression was positively correlated with mean corpuscular hemoglobin concentration and negatively correlated with neutrophil count, as well as standard deviation and coefficient of variation of red cell distribution width. These findings suggest that a decreased GDF11 expression may play a role in breast cancer pathogenesis.

The Effect of Liraglutide on Axon Regeneration and Functional Recovery after Peripheral Nerve Lesion

Peripheral nerve injuries inflict severe consequences, necessitating innovative therapeutic strategies. This study investigates the potential of liraglutide, a glucagon-like peptide-1 receptor agonist, in mitigating the consequences of peripheral nerve injury. The existing treatment methods for such injuries underscore the importance of ongoing translational research efforts. Thirty adult Wistar rats underwent sciatic nerve dissection and repair surgery. The nerves were surgically transected using micro scissors at a precise location located 1.5 cm proximal to the trifurcation site. The study included a control group and two experimental groups, one treated with saline (placebo group) and the other with liraglutide (experimental group) for 12 weeks. Motor function, electromyography (EMG), and biochemical and histopathological analyses were performed after 12 weeks of treatment. Electrophysiological assessments revealed that liraglutide improved the compound muscle action potential (CMAP) amplitude and motor function compared to the saline-treated group. Histological and immunohistochemical analyses demonstrated increased NGF expression, total axon number, and diameter and reduced fibrosis in the liraglutide group. Biochemical analyses illustrated liraglutide's antioxidative properties, evidenced by reduced malondialdehyde (MDA) levels. Galectin-3 levels were suppressed and GDF-11 levels were modulated by liraglutide, indicating anti-inflammatory and anti-apoptotic effects. Liraglutide is a promising therapeutic intervention for peripheral nerve injuries, promoting functional recovery and histopathological improvement. Its multifaceted positive impact, beyond glycemic control, suggests constructive effects on the acute and chronic inflammatory processes associated with peripheral neuropathy. These findings warrant further research to elucidate molecular mechanisms and facilitate clinical translation. The study contributes valuable insights to the growing understanding of GLP-1 receptor agonists' neuroprotective properties in the context of peripheral nerve injuries.

Silencing of GDF11 suppresses hepatocyte apoptosis to relieve LPS/D-GalN acute liver failure

In this paper, we generated a short hairpin RNA growth differentiation factor-11 (sh-GDF11) and evaluated the effects of sh-GDF11 on the pathogenesis of acute liver failure (ALF) in vitro and in vivo. Through bioinformatics study, the key gene related to ALF was assayed. Lipopolysaccharide (LPS) and D-galactoamine (D-GalN) were applied to establish the mouse model of LPS/D-GalN-induced liver injury, and TNF-α and D-Gal were used to construct an in vitro cell model, followed by treatment of sh-GDF11 for analysis of liver cell proliferation. Bioinformatics analysis showed that the protective effect of sh-GDF11 on ALF may be mediated by phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. The results of in vitro study found that sh-GDF11 could promote cell proliferation and inhibit death by blocking the PI3K/Akt/mTOR signaling pathway. In vivo animal experiments further confirmed that sh-GDF11 could suppress hepatocyte apoptosis by inhibiting the PI3K/Akt/mTOR signaling pathway. sh-GDF11 relieved LPS/D-GalN-induced ALF by blocking the PI3K/Akt/mTOR signaling pathway, emphasizing its critical role in LPS/D-GalN-induced ALF treatment.