Bone morphogenetic protein (BMP) 7 expression is regulated by the E3 ligase UBE4A in diabetic nephropathy

Directed osteogenic differentiation of human bone marrow mesenchymal stem cells via sustained release of BMP4 from PBVHx-based nanoparticles

Bone Morphogenetic Protein 4 (BMP4) is crucial for bone and cartilage tissue regeneration, essential in medical tissue engineering, cosmetology, and aerospace. However, its cost and degradation susceptibility pose significant clinical challenges. To enhance its osteogenic activity while reducing dosage and administration frequency, we developed a novel long-acting BMP4 delivery system using poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PBVHx) nanoparticles with soybean lecithin-modified BMP4 (sBP-NPs). These nanoparticles promote directed osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) through sustained BMP4 release. sBP-NPs exhibited uniform size (100-200 nm) and surface charges, with higher BMP4 entrapment efficiency (82.63 %) compared to controls. After an initial burst release within 24 h, sBP-NPs achieved 80 % cumulative BMP4 release within 20 days, maintaining levels better than control BP-NPs with unmodified BMP4. Co-incubation and nanoparticle uptake experiments confirmed excellent biocompatibility of sBP-NPs, promoting hBMSC differentiation towards osteogenic lineage with increased expression of type I collagen, calcium deposition, and ALP activity (> 20,000 U/g protein) compared to controls. Moreover, hBMSCs treated with sBP-NPs exhibited heightened expression of osteogenic genetic markers, surpassing control groups. Hence, this innovative strategy of sustained BMP4 release from sBP-NPs holds potential to revolutionize bone regeneration in minimally invasive surgery, medical cosmetology or space environments.

Depiction of Branched-Chain Amino Acids (BCAAs) in Diabetes with a Focus on Diabetic Microvascular Complications

Type 2 diabetes mellitus (T2DM) still holds the title as one of the most debilitating chronic diseases with rising prevalence and incidence, including its complications such as retinal, renal, and peripheral nerve disease. In order to develop novel molecules for diagnosis and treatment, a deep understanding of the complex molecular pathways is imperative. Currently, the existing agents for T2DM treatment target only blood glucose levels. Over the past decades, specific building blocks of proteins-branched-chain amino acids (BCAAs) including leucine, isoleucine, and valine-have gained attention because they are linked with insulin resistance, pre-diabetes, and diabetes development. In this review, we discuss the hypothetical link between BCAA metabolism, insulin resistance, T2DM, and its microvascular complications including diabetic retinopathy and diabetic nephropathy. Further research on these amino acids and their derivates may eventually pave the way to novel biomarkers or therapeutic concepts for the treatment of diabetes and its accompanied complications.

The emerging insight into E3 ligases as the potential therapeutic target for diabetic kidney disease

Diabetic kidney disease (DKD) is a major diabetic complication and global health concern, occurring in nearly 30 % to 40 % of people with diabetes. Importantly, several therapeutic strategies are being used against DKD; however, available treatments are not uniformly effective and the continuous rise in the prevalence of DKD demands more potential therapeutic approaches or targets. Epigenetic modifiers are regarded for their potential therapeutic effects against DKD. E3 ligases are such epigenetic modifier that regulates the target gene expression by attaching ubiquitin to the histone protein. In recent years, the E3 ligases came up as a potential therapeutic target as it selectively attaches ubiquitin to the substrate proteins in the ubiquitination cascade and modulates cellular homeostasis. The E3 ligases are also actively involved in DKD by regulating the expression of several proteins involved in the proinflammatory and profibrotic pathways. Burgeoning reports suggest that several E3 ligases such as TRIM18 (tripartite motif 18), Smurf1 (Smad ubiquitination regulatory factor 1), and NEDD4-2 (neural precursor cell-expressed developmentally downregulated gene 4-2) are involved in kidney epithelial-mesenchymal transition, inflammation, and fibrosis by regulating respective signaling pathways. However, the various signaling pathways that are regulated by different E3 ligases in the progression of DKD are poorly understood. In this review, we have discussed E3 ligases as potential therapeutic target for DKD. Moreover, different signaling pathways regulated by E3 ligases in the progression of DKD have also been discussed.

Urinary Markers of Tubular Injury and Renal Fibrosis in Patients with Type 2 Diabetes and Different Phenotypes of Chronic Kidney Disease

This study assessed the urinary excretion of markers and mediators of tubular injury and renal fibrosis in patients with type 2 diabetes (T2D) and non-albuminuric and albuminuric patterns of chronic kidney disease (CKD). One hundred and forty patients with long-term T2D and different patterns of CKD and twenty non-diabetic individuals were included. Urinary retinol-binding protein 4 (RBP-4), glutathione-S-transferase α₁ and π (GST-α₁ and GST-π), transforming growth factor β (TGF-β), type I and type IV collagen (Col1 and Col4), bone morphogenic protein 7 (BMP-7), and hepatocyte growth factor (HGF) were assessed by ELISA. Patients with T2D demonstrated increased urinary excretion of RBP-4, GST-π, Col4, BMP-7, and HGF (all p < 0.05 vs. control). The excretion of RBP-4, GST-π, Col1, and Col4 was increased in patients with elevated albumin-to-creatinine ratio (UACR; all p < 0.05 vs. control), while BMP-7 and HGF were increased innormoalbuminuric patients also (p < 0.05). Urinary RBP-4, GST-α₁, Col1, Col4, and HGF correlated positively with UACR; meanwhile, no correlations with glomerular filtration rate were found. The results demonstrate that elevated urinary excretions of the markers of tubular injury (RBP-4, GST-π) and renal fibrosis (Col1, Col4), as well as HGF, an antifibrotic regulator, are associated with the albuminuric pattern of CKD in subjects with T2D.

PTBP3 modulates P53 expression and promotes colorectal cancer cell proliferation by maintaining UBE4A mRNA stability

The RNA binding protein PTBP3 was recently reported to play a critical role in multiple cancers, and the molecular mechanisms involved RNA splicing, 3′ end processing and translation. However, the role of PTBP3 in colorectal cancer (CRC) remains poorly explored. Herein, PTBP3 was upregulated in CRC and associated with a poor prognosis. PTBP3 knockdown in colorectal cancer cell lines restricted CRC proliferative capacities in vitro and in vivo. Mechanistically, PTBP3 regulated the expression of the E3 ubiquitin ligase UBE4A by binding the 3′ UTR of its mRNA, preventing its degradation. UBE4A participated in P53 degradation, and PTBP3 knockdown in colorectal cancer cell lines showed increased P53 expression. UBE4A overexpression rescued PTBP3 knockdown-induced inhibition of CRC cell proliferation and P53 expression. Our results demonstrated that PTBP3 plays an essential role in CRC cell proliferation by stabilizing UBE4A to regulate P53 expression and may serve as a new prognostic biomarker and effective therapeutic target for CRC.

The Active Compounds and Therapeutic Target of Tripterygium wilfordii Hook. f. in Attenuating Proteinuria in Diabetic Nephropathy: A Review

Tripterygium wilfordii Hook. f. (TWHF) is a traditional Chinese herbal medicine and widely used to treat diabetic kidney disease in China. Emerging evidences have revealed its ability to attenuate diabetic nephropathy (DN). Tripterygium wilfordii polyglycosides (TWPs), triptolide (TP), and celastrol are predominantly active compounds isolated from TWHF. The effects and molecular mechanisms of TWHF and its active compounds have been investigated in recent years. Currently, it is becoming clearer that the effects of TWHF and its active compounds involve in anti-inflammation, anti-oxidative stress, anti-fibrosis, regulating autophagy, apoptosis, and protecting podocytes effect. This review presents an overview of the current findings related to the effects and mechanisms of TWHF and its active compounds in therapies of DN, thus providing a systematic understanding of the mechanisms and therapeutic targets by which TWHF and its active compounds affect cells and tissues in vitro and in vivo.

An easy long-acting BMP7 release system based on biopolymer nanoparticles for inducing osteogenic differentiation of adipose mesenchymal stem cells

In contrast to the early acting bone morphogenetic protein 2, bone morphogenetic protein 7 (BMP7) plays a decisive role mainly in the late stages of bone formation. To overcome deactivation and degradation of expensive BMP7, we designed a novel long-acting BMP7 release system based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) nanoparticles to enable the induction of osteogenic differentiation in human adipose mesenchymal stem cells (ADSCs). In order to improve the encapsulation efficiency of BMP7 and avoid damage by organic solvents, BMP7 was modified and protected using the biosurfactant soybean lecithin. In an in vitro test, BMP7-soybean lecithin-P34HB nanoparticles (BMP7-SPNPs) showed a short initial burst of BMP7 release during the first 24h, followed by a steady increase to a cumulative 80% release in 20days. Compared with the rapid release of control P34HB nanoparticles without soybean phospholipids loaded with BMP7 without soybean lecithin, BMP7-SPNPs significantly reduced the initial burst of BMP7 release and stabilized the content of BMP7 to allow long-term osteogenic differentiation during the late phase of bone development. Human ADSCs treated with BMP7-SPNPs showed higher alkaline phosphatase activity and higher expression levels of genetic markers of osteogenic differentiation compared with the control group. Thus, the results indicate that BMP7-SPNPs can be used as a rapid and long-acting BMP7 delivery system for osteogenic differentiation.

lncRNA ZEB1-AS1 inhibits high glucose-induced EMT and fibrogenesis by regulating the miR-216a-5p/BMP7 axis in diabetic nephropathy

Diabetic nephropathy (DN) is one of the leading causes of mortality in diabetic patients. Long non-coding RNA zinc finger E-box binding homeobox 1 antisense 1 (ZEB1-AS1) plays a crucial role in the development of various diseases, including DN. However, the molecular mechanism of ZEB1-AS1 in DN pathogenesis remains elusive. An in vitro DN model was established by treating HK-2 cells with high glucose (HG). Quantitative polymerase chain reaction (qRT-PCR) was utilized to detect the expression levels of ZEB1-AS1, microRNA-216a-5p (miR-216a-5p), and bone morphogenetic protein 7 (BMP7). Western blot assay was used to evaluate the protein levels of BMP7, epithelial-to-mesenchymal transition (EMT)-related proteins, and fibrosis markers. Additionally, the interaction among ZEB1-AS1, miR-216a-5p, and BMP7 was predicted by MiRcode (http://www.mircode.org) and starBase 2.0 (omics_06102, omicX), and confirmed by luciferase reporter assay. ZEB1-AS1 and BMP7 were down-regulated, while miR-216a-5p was highly expressed in kidney tissues of DN patients. Consistently, HG treatment decreased the levels of ZEB1-AS1 and BMP7, whereas HG increased miR-216a-5p expression in HK-2 cells in a time-dependent manner. ZEB1-AS1 upregulation inhibited HG-induced EMT and fibrogenesis. Furthermore, ZEB1-AS1 directly targeted miR-216a-5p, and overexpression of miR-216a-5p restored the inhibitory effects of ZEB1-AS1 overexpression on EMT and fibrogenesis. BMP7 was negatively targeted by miR-216a-5p. In addition, ZEB1-AS1 suppressed HG-induced EMT and fibrogenesis by regulating miR-216a-5p and BMP-7. lncRNA ZEB1-AS1 inhibited high glucose-induced EMT and fibrogenesis via regulating miR-216a-5p/BMP7 axis in diabetic nephropathy, providing a potential target for DN therapy.

Branched Chain Amino Acids Protects Rat Mesangial Cells from High Glucose by Modulating TGF-β1 and BMP-7

AIM

Branched-chain amino acids (BCAAs) have been reported owning curative effects in early diabetic nephropathy. However, the mechanisms of its action have not been elucidated. The aim of this study is to investigate the effect of possible mechanism(s) of BCAAs on cultured rat mesangial cells (RMCs).

METHODS

RMCs were treated with high glucose (30 mmol/L) and BCAAs (10 mmol/L) respectively. Cell proliferation was detected using an MTT assay. Expression of transforming growth factor (TGF)-β1 and gremlin mRNA was detected by semiquantitative reverse-transcription (RT) PCR. TGF-β1 and fibronectin (FN) protein levels were measured using enzyme-linked immunosorbent assays (ELISAs). Gremlin, bone morphogenic protein (BMP)-7, and Smad2/3 proteins were detected by immunofluorescence. Smad1/5/8 and phosphorylated (p)-Smad1/5/8 were detected by Western blotting.

RESULTS

The proliferation rate of the RMCs in the high glucose group alone was 1.45-times of cells in the CON group, and it was reduced by 32% upon co-treatment with BCAAs. The expression of TGF-β1, gremlin, p-Smd2/3 and FN mRNA or protein in the HG group was higher than that in the CON group. In the BCAAs group, the corresponding levels were lower than that in HG group. The expression of BMP-7 and p-Smad1/5/8 were significantly lower in the HG group than in the CON group. Moreover, the expression of BMP-7 and p-Smad1/5/8 were higher in the BCAAs group than in the HG group.

CONCLUSION

BCAAs showed an antidiabetic effect via reducing TGF-β1-Smad2/3 pathway and Gremlin expression and upregulating BMP-7-Smad1/5/8 pathway in rat mesangial cells, consequently lessening ECM deposition in renal tissue.