Deletion of Gremlin1 increases cell proliferation and migration responses in mouse embryonic fibroblasts

Biomarkers Assessing the Role of Cumulus Cells on IVF Outcomes: A Systematic Review

PURPOSE

Although significant improvements in assisted reproductive technology (ART) outcomes have been accomplished, a critical question remains: which embryo is most likely to result in a pregnancy? Embryo selection is currently based on morphological and genetic criteria; however, these criteria do not fully predict good-quality embryos and additional objective criteria are needed. The cumulus cells are critical for oocyte and embryo development. This systematic review assessed biomarkers in cumulus-oocyte complexes and their association with successful IVF outcomes.

METHODS

A comprehensive search was conducted using PubMed, Embase, Scopus, and Web of Science from inception until November 2022. Only English-language publications were included. Inclusion criteria consisted of papers that evaluated genetic biomarkers associated with the cumulus cells (CCs) in humans and the following three outcomes of interest: oocyte quality, embryo quality, and clinical outcomes, including fertilization, implantation, pregnancy, and live birth rates.

RESULTS

The search revealed 446 studies of which 42 met eligibility criteria. Nineteen studies correlated genetic and biochemical biomarkers in CCs with oocyte quality. A positive correlation was reported between oocyte quality and increased mRNA expression in CCs of genes encoding for calcium homeostasis (CAMK1D), glucose metabolism (PFKP), extracellular matrix (HAS2, VCAN), TGF-β family (GDF9, BMP15), and prostaglandin synthesis (PTGS2). Nineteen studies correlated genetic and biochemical biomarkers in CCs with embryo quality. A positive correlation was reported between embryo quality and increased mRNA expression in CCs of genes encoding for extracellular matrix (HAS2), prostaglandin synthesis (PTGS2), steroidogenesis (GREM1), and decreased expression of gene encoding for hormone receptor (AMHR2). Twenty-two studies assessed genetic and biochemical biomarkers in CCs with clinical outcomes. Increased expression of genes encoding for extracellular matrix (VCAN), and TGF-β family (GDF9, BMP15) were positively correlated with pregnancy rate.

CONCLUSION

Genetic biomarkers from cumulus cells were associated with oocyte quality (CAMK1D, PFKP, HAS2, VCAN, GDF-9, BMP-15, PTGS2), embryo quality (GREM1, PTGS2, HAS2), and pregnancy rate (GDF9, BMP15, VCAN). These results might help guide future studies directed at tests of cumulus cells to devise objective criteria to predict IVF outcomes.

Current status and prospects of GREM1 research in cancer (Review)

GREM1 is a secreted protein that antagonizes bone morphogenetic proteins (BMPs) and participates in critical biological processes, including embryonic development, organogenesis and tissue differentiation. Gremlin 1 (GREM1) is also an inhibitor of TGF-β and a ligand for vascular endothelial growth factor receptor 2. In addition, GREM1 can induce cells, participate in the process of epithelial-mesenchymal transition, and then participate in tumor development. GREM1 has a variety of biological functions and can participate in the malignant progression of a variety of tumors through the BMP signaling pathway. GREM1 also can inhibit TGF-β in some tumors, thereby inhibiting tumors, and its involvement in tumor development varies in different types of cancer. The present review examines the role and function of GREM1 in tumors. GREM1 is expressed in a variety of tumor types. GREM1 expression can affect the epithelial-mesenchymal transformation of tumor cells. GREM1 has been studied in breast and colon cancer, and its potential role is to promote cancer. However, in pancreatic cancer, which was found to act differently from other cancer types, overexpression of GREM1 inhibits tumor metastasis. The present review suggests that GREM1 can be a diagnostic and prognostic indicator. In future studies, the study of GREM1 based on single-cell sequencing technology will further clarify its role and function in tumors.

Overexpression of GREM1 Improves the Survival Capacity of Aged Cardiac Mesenchymal Progenitor Cells via Upregulation of the ERK/NRF2-Associated Antioxidant Signal Pathway

Ischemic heart disease is the leading cause of mortality in the United States. Progenitor cell therapy can restore myocardial structure and function. However, its efficacy is severely limited by cell aging and senescence. Gremlin-1 (GREM1), a member of the bone morphogenetic protein antagonist family, has been implicated in cell proliferation and survival. However, GREM1's role in cell aging and senescence has never been investigated in human cardiac mesenchymal progenitor cells (hMPCs). Therefore, this study assessed the hypothesis that overexpression of GREM1 rejuvenates the cardiac regenerative potential of aging hMPCs to a youthful stage and therefore allows better capacity for myocardial repair. We recently reported that a subpopulation of hMPCs with low mitochondrial membrane potential can be sorted from right atrial appendage-derived cells in patients with cardiomyopathy and exhibit cardiac reparative capacity in a mouse model of myocardial infarction. In this study, lentiviral particles were used to overexpress GREM1 in these hMPCs. Protein and mRNA expression were assessed through Western blot and RT-qPCR. FACS analysis for Annexin V/PI staining and lactate dehydrogenase assay were used to assess cell survival. It was observed that cell aging and cell senescence led to a decrease in GREM1 expression. In addition, overexpression of GREM1 led to a decrease in expression of senescence genes. Overexpression of GREM1 led to no significant change in cell proliferation. However, GREM1 appeared to have an anti-apoptotic effect, with an increase in survival and decrease in cytotoxicity evident in GREM1-overexpressing hMPCs. Overexpressing GREM1 also induced cytoprotective properties by decreasing reactive oxidative species and mitochondrial membrane potential. This result was associated with increased expression of antioxidant proteins, such as SOD1 and catalase, and activation of the ERK/NRF2 survival signal pathway. Inhibition of ERK led to a decrease in GREM1-mediated rejuvenation in terms of cell survival, which suggests that an ERK-dependent pathway may be involved. Taken altogether, these results indicate that overexpression of GREM1 can allow aging hMPCs to adopt a more robust phenotype with improved survival capacity, which is associated with an activated ERK/NRF2 antioxidant signal pathway.

GREM1/PPP2R3A expression in heterogeneous fibroblasts initiates pulmonary fibrosis

Background

Fibroblasts have important roles in the synthesis and remodeling of extracellular matrix (ECM) proteins during pulmonary fibrosis. However, the spatiotemporal distribution of heterogeneous fibroblasts during disease progression remains unknown.

Results

In the current study, silica was used to generate a mouse model of pathological changes in the lung, and single-cell sequencing, spatial transcriptome sequencing and an analysis of markers of cell subtypes were performed to identify fibroblast subtypes. A group of heterogeneous fibroblasts that play an important role at the early pathological stage were identified, characterized based on the expression of inflammatory and proliferation genes (termed inflammatory-proliferative fibroblasts) and found to be concentrated in the lesion area. The expression of GREM1/protein phosphatase 2 regulatory subunit B''alpha (PPP2R3A) in inflammatory-proliferative fibroblasts was found to initiate early pulmonary pathological changes by increasing the viability, proliferation and migration of cells.

Conclusions

Inflammatory-proliferative fibroblasts play a key role in the early pathological changes that occur in silicosis, and during this process, GREM1 is the driving factor that targets PPP2R3A and initiates the inflammatory response, which is followed by irreversible fibrosis induced by SiO₂. The GREM1/PPP2R3A pathway may be a potential target in the early treatment of silicosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00860-0.

Protective role of microRNA-23a/b-3p inhibition against osteoarthritis through Gremlin1-depenent activation of TGF-β/smad signaling in chondrocytesa

The changed biomechanical environment of chondrocytes elicited by altered extracellular matrix is reported to accelerate the progression of OA. MicroRNAs (miRNAs or miRs) have emerged as major regulators in chondrocyte function. Hence, we explored effect of miR-23a/b-3p on OA in regulating chondrocyte growth. The medial meniscus and anterior cruciate ligaments of right knee was removed to induce a mouse model of OA. miR-23a/b-3p and Gremlin1 (Grem1) expressions in OA were determined by RT-qPCR. Dual luciferase reporter gene assay was conducted to assess their relationship in the context of OA. Loss- and gain-of-function assays were adopted to clarify their effects on OA by determining the release of pro-inflammatory proteins and the apoptosis of chondrocytes. RT-qPCR determined increased miR-23a/b-3p expression and decreased Grem1 expression in the setting OA. Inhibiting miR-23a/b-3p or overexpressing Grem1 activated transforming growth factor-β/solvated metal atom dispersed 3 (TGF-β/Smad) signaling to prevent OA development. Silencing Grem1 ablated suppressive effects of miR-23a/b-3p inhibitor on the release of pro-inflammatory proteins and the apoptosis of chondrocytes. To conclude, inhibition of miR-23a/b-3p delays OA progression through Grem1-mediated activation of TGF-β/Smad signaling, contributing to deepen understanding of the pathogenesis of OA.

Determination of the roles of GREM1 gene in granulosa cell proliferation and steroidogenesis of hen ovarian prehierarchical follicles

Gremlin genes are known members of the DAN family of bone morphogenetic protein (BMP) antagonists, but their functions and regulatory mechanisms in ovarian follicular development of chicken remain unknown. The current study was designed to investigate the mRNA expression patterns of gremlin1 gene (GREM1) and its protein location in the follicles sampled, and to explore the biological effect of GREM1 on the prehierarchical follicular development. This work revealed that chicken GREM1 mRNA exhibits a constant expression level across all the prehierarchical follicles (PFs) from 1-4 mm to 7-8 mm in diameter, and the preovulatory follicles (from F6 to F1) by using RT-qPCR (P > 0.05). The GREM1 protein is predominantly expressed in the oocytes and granulosa cells (GCs) of the PFs by immunohistochemistry. Furthermore, our data demonstrated that siRNA-mediated knockdown of GREM1 in the GCs resulted in a significant reduction in cell proliferation (P < 0.001); conversely, overexpression of GREM1 in the GCs led to a remarkable increase in cell proliferation (P < 0.001). Interestingly, the expression levels of proliferating cell nuclear antigen (PCNA) and cyclin D2 (CCND2) mRNA and proteins were notably increased when GREM1 expression was upregulated in the GCs (P < 0.01), however, the expression levels of CYP11A1 and StAR were markedly downregulated (P < 0.01). The current results showed that GREM1 gene plays a stimulatory role in GC proliferation during growth and development of the prehierarchical follicles in vitro but an inhibitory role in GC differentiation and steroidogenesis of the hen ovary follicles.

Noggin inhibits hypoxia-induced proliferation by targeting store-operated calcium entry and transient receptor potential cation channels

Abnormally elevated bone morphogenetic protein 4 (BMP4) expression and mediated signaling play a critical role in the pathogenesis of chronic hypoxia-induced pulmonary hypertension (CHPH). In this study, we investigated the expression level and functional significance of four reported naturally occurring BMP4 antagonists, noggin, follistatin, gremlin1, and matrix gla protein (MGP), in the lung and distal pulmonary arterial smooth muscle cell (PASMC). A 21-day chronic hypoxic (10% O2) exposure rat model was utilized, which has been previously shown to successfully establish experimental CHPH. Among the four antagonists, noggin, but not the other three, was selectively downregulated by hypoxic exposure in both the lung tissue and PASMC, in correlation with markedly elevated BMP4 expression, suggesting that the loss of noggin might account for the hypoxia-triggered BMP4 signaling transduction. Then, by using treatment of extrogenous recombinant noggin protein, we further found that noggin significantly normalized 1) BMP4-induced phosphorylation of cellular p38 and ERK1/2; 2) BMP4-induced phosphorylation of cellular JAK2 and STAT3; 3) hypoxia-induced PASMC proliferation; 4) hypoxia-induced store-operated calcium entry (SOCE), and 5) hypoxia-increased expression of transient receptor potential cation channels (TRPC1 and TRPC6) in PASMC. In combination, these data strongly indicated that the hypoxia-suppressed noggin accounts, at least partially, for hypoxia-induced excessive PASMC proliferation, while restoration of noggin may be an effective way to inhibit cell proliferation by suppressing SOCE and TRPC expression.

Gremlin1 preferentially binds to bone morphogenetic protein-2 (BMP-2) and BMP-4 over BMP-7

Gremlin1 has a distinct preference for which bone morphogenetic protein it binds to in kidney epithelial cells. Grem1–BMP-2 complexes are favoured over other BMPs, and this may play an important role in fibrotic kidney disease.

Expression of gremlin 1 correlates with increased angiogenesis and progression-free survival in patients with pancreatic neuroendocrine tumors

BACKGROUND

Gremlin 1 (GREM1) is a bone morphogenetic protein antagonist and a novel proangiogenic factor. Our aim was to evaluate the prognostic value of GREM1 expression and GREM1-related factors in tumor-associated angiogenesis in pancreatic neuroendocrine tumors (NETs).

METHODS

The immunohistochemical expression of GREM1 and microvessel density (MVD) were examined in 35 patients with pancreatic NETs and then compared with other clinicopathologic characteristics, including the World Health Organization classification.

RESULTS

The presence of expression of GREM1 (p = 0.016) and high MVD (p = 0.020) were significant and favorable prognostic factors. Moreover, GREM1 expression was significantly associated with high MVD (p = 0.011). MVD was significantly higher in well-differentiated NETs than in well-differentiated or poorly differentiated neuroendocrine carcinomas (p < 0.001).

CONCLUSIONS

GREM1 expression was correlated with tumor-associated angiogenesis and was found to be a novel prognostic marker in pancreatic NETS. Our data support a tumor suppressor role of GREM1 in pancreatic NETs.