Transforming Growth Factor-β Receptors and Smads: Regulatory Complexity and Functional Versatility

Tetratricopeptide repeat domain 36 deficiency mitigates renal tubular injury by inhibiting TGF-β1-induced epithelial-mesenchymal transition in a mouse model of chronic kidney disease

The damage of proximal tubular epithelial cells (PTECs) is considered a central event in the pathogenesis of chronic kidney disease (CKD) and deregulated repair processes of PTECs result in epithelial–mesenchymal transition (EMT), which in turn aggravates tubular injury and kidney fibrosis. In this study, we firstly revealed that the reduction of TTC36 is associated with unilateral ureteral obstruction (UUO)-induced CKD; besides, ablation of TTC36 attenuated tubular injury and subsequent EMT in UUO-treated mice kidneys. Consistently, TTC36 overexpression promoted EMT in TGF-β1-induced HK2 cells. Moreover, TTC36 elevated the protein expression of CEBPB, which was involved in the regulation of TGF-β/SMAD3 signaling, and augmented SMAD3 signaling and downstream genetic response were reduced by CEBPB silencing. Collectively, our results uncovered that TTC36 deficiency plays a protective role in tubular injury and renal fibrosis triggered by UUO; further, TTC36 overexpression exacerbated TGF-β/SMAD3 signaling via elevating the stability of SMAD3 and CEBPB, suggesting that TTC36 inhibition may be a potential strategy in the therapy of obstructive nephropathy.

Extracranial arteriovenous malformations demonstrate dysregulated TGF-β/BMP signaling and increased circulating TGF-β1

Extracranial arteriovenous malformations (AVMs) are characterized by anomalous arterial-to-venous connections, aberrant angiogenesis, local inflammation and hypoxia, and disorganized histological architecture; however, the precise molecular perturbations leading to this phenotype remain elusive. We hypothesized that extracranial AVM tissue would demonstrate deregulation of the TGF-β/BMP signaling pathway, which may serve as a potential target in the development of molecular-based therapies for AVMs. AVM tissue was harvested during resection from 10 patients with AVMs and compared to control tissue. Blood was collected from 14 AVM patients and 10 patients without AVMs as controls. Expression of TGF-β/BMP pathway components was analyzed using RT-PCR, western blotting, and immunohistochemistry. Circulating levels of TGF-β1 were analyzed by ELISA. Paired t tests were utilized to perform statistical analysis. The mRNA levels of TGF-β1, ALK1, Endoglin (ENG), Smad6, Smad7, and Smad8 were significantly elevated in AVM tissue when compared to controls. Protein levels of TGF-β1 and Smad3 were elevated in AVM tissue while protein levels of BMP-9, ALK1, Smad1, Smad6, and Smad8 were significantly decreased in AVMs. Immunohistochemistry demonstrated increased TGF-β1 in the perivascular cells of AVMs compared to normal controls, and circulating levels of TGF-β1 were significantly higher in AVM patients. Patients with AVMs demonstrate aberrant TGF-β/BMP expression in AVM tissue and blood compared to controls. Targeting aberrantly expressed components of the TGF-β/BMP pathway in extracranial AVMs may be a viable approach in the development of novel molecular therapies, and monitoring circulating TGF-β1 levels may be a useful indicator of treatment success.

The comprehensive detection of miRNA and circRNA in the regulation of intramuscular and subcutaneous adipose tissue of Laiwu pig

circRNAs, as miRNA sponges, participate in many important biological processes. However, it remains unclear whether circRNAs can regulate lipid metabolism. This study aimed to explore the competing endogenouse RNA (ceRNA) regulatory network that affects the difference between intramuscular fat (IMF) and subcutaneous fat (SCF) deposition, and to screen key circRNAs and their regulatory genes. In this experiment, we identified 265 differentially expressed circRNAs, of which 187 up-regulated circRNA and 78 down-regulated circRNA in IMF. Subsequently, we annotated the function of DEcircRNA's host genes, and found that DEcircRNA's host genes were mainly involved in GO terms (including cellular response to fatty acids, lysophosphatidic acid acyltransferase activity, R-SMAD binding, etc.) and signaling pathways (fatty acid biosynthesis, Citrate cycle, TGF- β Signal pathway) related to adipogenesis, differentiation and lipid metabolism. By constructing a circRNA-miRNA network, we screened out DEcircRNA that can competitively bind to more miRNAs as key circRNAs (circRNA_06424 and circRNA_08840). Through the functional annotation of indirect target genes and protein network analysis, we found that circRNA_06424 affects the expression of PPARD, MMP9, UBA7 and other indirect target genes by competitively binding to miRNAs such as ssc-miR-339-5p, ssc-miR-744 and ssc-miR-328, and participates in PPAR signaling pathway, Wnt signaling pathway, unsaturated fatty acid and other signaling pathways, resulting in the difference of fat deposition between IMF and SCF. This study provide a theoretical basis for further research investigating the differences of lipid metabolism in different adipose tissues, providing potential therapeutic targets for ectopic fat deposition and lipid metabolism diseases.

SMAD3 contributes to ascending aortic dilatation independent of transforming growth factor-beta in bicuspid and unicuspid aortic valve disease

We sought to determine whether there are differences in transforming growth factor-beta (TGFß) signaling in aneurysms associated with bicuspid (BAV) and unicuspid (UAV) aortic valves versus normal aortic valves. Ascending aortic aneurysms are frequently associated with BAV and UAV. The mechanisms are not yet clearly defined, but similarities to transforming growth factor-beta TGFß vasculopathies (i.e. Marfan, Loeys-Dietz syndromes) are reported. Non-dilated (ND) and aneurysmal (D) ascending aortic tissue was collected intra-operatively from individuals with a TAV (N = 10ND, 10D), BAV (N = 7ND, 8D) or UAV (N = 7ND, 8D). TGFß signaling and aortic remodeling were assessed through immuno-assays and histological analyses. TGFß1 was increased in BAV/UAV-ND aortas versus TAV (P = 0.02 and 0.04, respectively). Interestingly, TGFß1 increased with dilatation in TAV (P = 0.03) and decreased in BAV/UAV (P = 0.001). In TAV, SMAD2 and SMAD3 phosphorylation (pSMAD2, pSMAD3) increased with dilatation (all P = 0.04) and with TGFß1 concentration (P = 0.04 and 0.03). No relationship between TGFß1 and pSMAD2 or pSMAD3 was observed for BAV/UAV (all P > 0.05). pSMAD3 increased with dilatation in BAV/UAV aortas (P = 0.01), whereas no relationship with pSMAD2 was observed (P = 0.56). Elastin breaks increased with dilatation in all groups (all P < 0.05). In TAV, elastin degradation correlated with TGFß1, pSMAD2 and pSMAD3 (all P < 0.05), whereas in BAV and UAV aortas, elastin degradation correlated only with pSMAD3 (P = 0.0007). TGFß signaling through SMAD2/SMAD3 contributes to aortic remodeling in TAV, whereas TGFß-independent activation of SMAD3 may underlie aneurysm formation in BAV/UAV aortas. Therefore, SMAD3 should be further investigated as a therapeutic target against ascending aortic dilatation in general, and particularly in BAV/UAV patients.

The novel role of ER protein TXNDC5 in the pathogenesis of organ fibrosis: mechanistic insights and therapeutic implications

Fibrosis-related disorders account for an enormous burden of disease-associated morbidity and mortality worldwide. Fibrosis is defined by excessive extracellular matrix deposition at fibrotic foci in the organ tissue following injury, resulting in abnormal architecture, impaired function and ultimately, organ failure. To date, there lacks effective pharmacological therapy to target fibrosis per se, highlighting the urgent need to identify novel drug targets against organ fibrosis. Recently, we have discovered the critical role of a fibroblasts-enriched endoplasmic reticulum protein disulfide isomerase (PDI), thioredoxin domain containing 5 (TXNDC5), in cardiac, pulmonary, renal and liver fibrosis, showing TXNDC5 is required for the activation of fibrogenic transforming growth factor-β signaling cascades depending on its catalytic activity as a PDI. Moreover, deletion of TXNDC5 in fibroblasts ameliorates organ fibrosis and preserves organ function by inhibiting myofibroblasts activation, proliferation and extracellular matrix production. In this review, we detailed the molecular and cellular mechanisms by which TXNDC5 promotes fibrogenesis in various tissue types and summarized potential therapeutic strategies targeting TXNDC5 to treat organ fibrosis.

Regional specific differentiation of integumentary organs: SATB2 is involved in α- and β-keratin gene cluster switching in the chicken

BACKGROUND

Animals develop skin regional specificities to best adapt to their environments. Birds are excellent models in which to study the epigenetic mechanisms that facilitate these adaptions. Patients suffering from SATB2 mutations exhibit multiple defects including ectodermal dysplasia-like changes. The preferential expression of SATB2, a chromatin regulator, in feather-forming compared to scale-forming regions, suggests it functions in regional specification of chicken skin appendages by acting on either differentiation or morphogenesis.

RESULTS

Retrovirus mediated SATB2 misexpression in developing feathers, beaks, and claws causes epidermal differentiation abnormalities (e.g. knobs, plaques) with few organ morphology alterations. Chicken β-keratins are encoded in 5 sub-clusters (Claw, Feather, Feather-like, Scale, and Keratinocyte) on Chromosome 25 and a large Feather keratin cluster on Chromosome 27. Type I and II α-keratin clusters are located on Chromosomes 27 and 33, respectively. Transcriptome analyses showed these keratins (1) are often tuned up or down collectively as a sub-cluster, and (2) these changes occur in a temporo-spatial specific manner.

CONCLUSIONS

These results suggest an organizing role of SATB2 in cluster-level gene co-regulation during skin regional specification.

MiR-221-5p/Smad3 axis in osteoclastogenesis and its function: Potential therapeutic target for osteoporosis

OBJECTIVE

To probe the role of miR-221-5p in osteoclastogenesis and the underlying mechanism.

METHODS

Serum from patients with postmenopausal osteoporosis and healthy controls was collected for determination of miR-221-5p expression. For in vitro experiment, RAW264.7 macrophages, in which the expression of miR-221-5p and/or Smad3 was altered, were induced by RANKL to differentiate into osteoclasts. For in vivo experiment, ovariectomy was performed to construct osteoporosis mouse models, followed by tail vein injection of miR-221-5p agomir. qRT-PCR and/or western blot were applied to measure the expression of miR-221-5p, Smad3, and osteoclastogenesis-related genes (NFATc1 and TRAF6). TRAP staining was utilized for assessment of osteoclast formation, MTT assay for assessment of osteoclast viability, and H&E staining for observation of histomorphological changes. The targeting relationship between miR-221-5p and Smad3 was verified by dual-luciferase reporter gene assay.

RESULTS

Compared with healthy controls, patients with postmenopausal osteoporosis had decreased miR-221-5p expression and lower lumbar vertebra bone mineral density. MiR-221-5p expression was decreased and Smad3 level was increased during osteoclastogenesis. The osteoclastogenesis was suppressed by miR-221-5p and promoted by Smad3, as evidenced by diminished number and viability of osteoclasts following overexpression of miR-221-5p or knockdown of Smad3. MiR-221-5p negatively mediated Smad3 expression. Smad3 suppression nullified the pro-osteoclastogenesis effect of miR-221-5p inhibition. Consistent results were observed in osteoporosis mouse models.

CONCLUSION

MiR-221-5p may alleviate postmenopausal osteoporosis through suppressing osteoclastogenesis via Smad3, which provides new ideas for molecule-targeted therapy of osteoporosis.

Activin receptor-like kinase 7 promotes apoptosis of vascular smooth muscle cells via activating Smad2/3 signaling in diabetic atherosclerosis

Vascular smooth muscle cells (VSMCs) is a vital accelerator in the late phase of diabetic atherosclerosis, but the underlying mechanism remains unclear. The aim of our study was to investigate whether activin receptor-like kinase 7 (ALK7)-Smad2/3 pathway plays an important role in VSMC apoptosis of diabetic atherosclerosis. It was shown that ALK7 expression was obviously elevated in the aorta of ApoE−/− mice with type 2 diabetes mellitus. Inhibition of ALK7 expression significantly improved the stability of atherosclerotic plaques and reduced cell apoptosis. Further experiments showed that ALK7 knockdown stabilized atherosclerotic plaques by reducing VSMC apoptosis via activating Smad2/3. Our study uncovered the important role of ALK7-Smad2/3 signaling in VSMCs apoptosis, which might be a potential therapeutic target in diabetic atherosclerosis.

Convergent dopamine and ALK4 signaling to PCBP1 controls FosB alternative splicing and cocaine behavioral sensitization

ΔfosB is an alternatively spliced product of the FosB gene that is essential for dopamine-induced reward pathways and that acts as a master switch for addiction. However, the molecular mechanisms of its generation and regulation by dopamine signaling are unknown. Here, we report that dopamine D1 receptor signaling synergizes with the activin/ALK4/Smad3 pathway to potentiate the generation of ΔFosB mRNA in medium spiny neurons (MSNs) of the nucleus accumbens (NAc) via activation of the RNA-binding protein PCBP1, a regulator of mRNA splicing. Concurrent activation of PCBP1 and Smad3 by D1 and ALK4 signaling induced their interaction, nuclear translocation, and binding to sequences in exon-4 and intron-4 of FosB mRNA. Ablation of either ALK4 or PCBP1 in MSNs impaired ΔFosB mRNA induction and nuclear translocation of ΔFosB protein in response to repeated co-stimulation of D1 and ALK4 receptors. Finally, ALK4 is required in NAc MSNs of adult mice for behavioral sensitization to cocaine. These findings uncover an unexpected mechanism for ΔFosB generation and drug-induced sensitization through convergent dopamine and ALK4 signaling.

Pancreatic ductal adenocarcinoma: Emerging therapeutic strategies

The seventh leading cause of cancer-related death globally, pancreatic ductal adenocarcinoma (PDAC) involves the exocrine pancreas and constitutes greater than 90% of all pancreatic cancers. Surgical resection in combination with systemic chemotherapy with or without radiation remains the mainstay of treatment and the only potentially curative treatment option. While there has been improvement in systemic chemotherapy, long-term survival among patients with PDAC remains poor. Improvement in the understanding of tumorigenesis, genetic mutations, the tumor microenvironment (TME), immunotherapies, as well as targeted therapies continued to drive advances in PDAC treatment. We herein review the TME, genetic landscape, as well as various metabolic pathways associated with PDAC tumorigenesis relative to emerging therapies.

Blood-Brain Barrier Dysfunction and Astrocyte Senescence as Reciprocal Drivers of Neuropathology in Aging

As the most abundant cell types in the brain, astrocytes form a tissue-wide signaling network that is responsible for maintaining brain homeostasis and regulating various brain activities. Here, we review some of the essential functions that astrocytes perform in supporting neurons, modulating the immune response, and regulating and maintaining the blood-brain barrier (BBB). Given their importance in brain health, it follows that astrocyte dysfunction has detrimental effects. Indeed, dysfunctional astrocytes are implicated in age-related neuropathology and participate in the onset and progression of neurodegenerative diseases. Here, we review two mechanisms by which astrocytes mediate neuropathology in the aging brain. First, age-associated blood-brain barrier dysfunction (BBBD) causes the hyperactivation of TGFβ signaling in astrocytes, which elicits a pro-inflammatory and epileptogenic phenotype. Over time, BBBD-associated astrocyte dysfunction results in hippocampal and cortical neural hyperexcitability and cognitive deficits. Second, senescent astrocytes accumulate in the brain with age and exhibit a decreased functional capacity and the secretion of senescent-associated secretory phenotype (SASP) factors, which contribute to neuroinflammation and neurotoxicity. Both BBBD and senescence progressively increase during aging and are associated with increased risk of neurodegenerative disease, but the relationship between the two has not yet been established. Thus, we discuss the potential relationship between BBBD, TGFβ hyperactivation, and senescence with respect to astrocytes in the context of aging and disease and identify future areas of investigation in the field.

A novel role of BK potassium channel activity in preventing the development of kidney fibrosis

Kidney fibrosis is a common characteristic of chronic kidney disease and while the large conductance voltage and calcium-activated potassium channel (BK) is widely expressed in kidneys, its role in kidney fibrosis is unknown. To evaluate this, we found that BK protein expression was decreased in the fibrotic kidneys. Accompanying this was increased fibrotic marker protein expression of fibronectin, vimentin and α-smooth muscle actin and increased mRNA expressions of fibronectin, α-smooth muscle actin, collagen III and collagen I. These changes occurred in the unilateral ureteral obstruction and folic acid models of fibrosis and were more pronounced in BK knockout than in wild-type mice. Activation of BK activity by chemical NS1619 or BMS191011 channel openers attenuated kidney fibrosis in these two models while protecting kidney function in wild-type mice. BK deficiency up-regulated transforming growth factor-β (TGF-β)/transcription factor Smad2/3 signaling in the fibrotic kidney, whereas activation of BK activity inhibited this signaling pathway both in vivo and in vitro. BK channel activation increased the degradation of TGF-β receptors induced by TGF-β1 in vivo and in vitro. Furthermore, in cell lines HK-2, NRK49, and NRK-52E, BK channel activation by NS1619 led to increased caveolae formation and facilitated localization of TGF-β receptors in the microdomains of lipid rafts. Thus, our data demonstrated that BK activation has an anti-fibrotic effect on kidney fibrosis by inhibiting the TGF-β signaling pathway through accelerating TGF-β receptor degradation via the caveolae route. Hence, our study provides innovative insight into BK as a potential therapeutic target for the treatment of kidney fibrosis.

Gene profiling of SEC13, SMAD7, GHRL, long non-coding RNA GHRLOS, HIF-1α in gastric cancer patients

Even with considerable progress in cancer researches, gastric cancer is still one of the global health problems. Recognition of the differential expressed genes in GC is the most appropriate approach for establishing new diagnostic targets. This study evaluates SEC13, SMAD7, GHRL, lncRNA GHRLOS, HIF-1α genes profiling as well as HIF-1α protein level for GC. The expression of selected genes, serum HIF-1α and CEA protein levels were determined for 50 GC patients and 50 healthy controls by real-time RT-PCR, ELISA, and ELICA respectively. The sensitivities of these parameters as diagnostic biomarkers were evaluated. SMAD7, HIF-1α expression, serum HIF-1α, and CEA level were significantly upregulated in GC patients as compared to the control group (P = 0.024, < 0.001) and had significant positive correlations between each other except SMAD7 with serum HIF-1α, and CEA level. On the other hand, SEC13, GHRL, and lncRNA GHRLOS expression were significantly downregulated in GC patients (P =  < 0.001, 0.025, < 0.001 respectively) and had significant positive correlations with each other (P < 0.001). Significant negative correlations were observed between most of both groups. All studied parameters were associated with GC clinical stages except SMAD7 was associated with stage IV only (P = 0.005) and GHRL did not associate with tumor stages (P ˃ 0.05). All studied parameters may be promising biomarkers for the early diagnosis of GC. SMAD7, HIF-1α gene, and HIF-1α protein may be jointly implicated in cancer development and prognosis, while SEC13, GHRL, and lncRNA GHRLOS may act as tumor suppressors.

Transforming growth factor-β challenge alters the N-, O-, and glycosphingolipid glycomes in PaTu-S pancreatic adenocarcinoma cells

Pancreatic ductal adenocarcinoma (PDAC) is characterized by poor prognosis and high mortality. Transforming growth factor-β (TGF-β) plays a key role in PDAC tumor progression, which is often associated with aberrant glycosylation. However, how PDAC cells respond to TGF-β and the role of glycosylation therein is not well known. Here, we investigated the TGF-β-mediated response and glycosylation changes in the PaTu-8955S (PaTu-S) cell line deficient in SMA-related and MAD-related protein 4 (SMAD4), a signal transducer of the TGF-β signaling. PaTu-S cells responded to TGF-β by upregulating SMAD2 phosphorylation and target gene expression. We found that TGF-β induced expression of the mesenchymal marker N-cadherin but did not significantly affect epithelial marker E-cadherin expression. We also examined differences in N-glycans, O-glycans, and glycosphingolipid-linked glycans in PaTu-S cells upon TGF-β stimulation. TGF-β treatment primarily induced N-glycome aberrations involving elevated levels of branching, core fucosylation, and sialylation in PaTu-S cells, in agreement with TGF-β-induced changes in the expression of glycosylation-associated genes. In addition, we observed differences in O glycosylation and glycosphingolipid glycosylation profiles after TGF-β treatment, including lower levels of sialylated Tn antigen and neoexpression of globosides. Furthermore, the expression of transcription factor sex-determining region Y-related high-mobility group box 4 was upregulated upon TGF-β stimulation, and its depletion blocked TGF-β-induced N-glycomic changes. Thus, TGF-β-induced N-glycosylation changes can occur in a sex-determining region Y-related high-mobility group box 4–dependent and SMAD4-independent manner in the pancreatic PaTu-S cancer cell line. Our results open up avenues to study the relevance of glycosylation in TGF-β signaling in SMAD4-inactivated PDAC.

The multifunctional adaptor protein HIP-55 couples Smad7 to accelerate TGF-β type I receptor degradation

Transforming growth factor β (TGF-β) is a multifunctional polypeptide that plays critical roles in regulating a broad range of cellular functions and physiological processes. TGF-β signalling dysfunction contributes to many disorders, such as cardiovascular diseases, cancer and immunological diseases. The homoeostasis of negative feedback regulation is critical for signal robustness, duration and specificity, which precisely control physiological and pathophysiological processes. However, the underlying mechanism by which the negative regulation of TGF-β signalling is integrated and coordinated is still unclear. Here, we reveal that haematopoietic progenitor kinase-interacting protein of 55 kDa (HIP-55) was upregulated upon TGF-β stimulation, while the loss of HIP-55 caused TGF-β signalling overactivation and the abnormal accumulation of downstream extracellular matrix (ECM) genes. HIP-55 interacts with Smad7 and competes with Smad7/Axin complex formation to inhibit the Axin-mediated degradation of Smad7. HIP-55 further couples Smad7 to TβRI but not TβRII, driving TβRI degradation. Altogether, our findings demonstrate a new mechanism by which the effector and negative feedback functions of HIP-55 are coupled and may provide novel strategies for the treatment of TGF-β signalling-related human diseases.

Competition between type I activin and BMP receptors for binding to ACVR2A regulates signaling to distinct Smad pathways

Background

Activins and bone morphogenetic proteins (BMPs) play critical, sometimes opposing roles, in multiple physiological and pathological processes and diseases. They signal to distinct Smad branches; activins signal mainly to Smad2/3, while BMPs activate mainly Smad1/5/8. This gives rise to the possibility that competition between the different type I receptors through which activin and BMP signal for common type II receptors can provide a mechanism for fine-tuning the cellular response to activin/BMP stimuli. Among the transforming growth factor-β superfamily type II receptors, ACVR2A/B are highly promiscuous, due to their ability to interact with different type I receptors (e.g., ALK4 vs. ALK2/3/6) and with their respective ligands [activin A (ActA) vs. BMP9/2]. However, studies on complex formation between these full-length receptors situated at the plasma membrane, and especially on the potential competition between the different activin and BMP type I receptors for a common activin type II receptor, were lacking.

Results

We employed a combination of IgG-mediated patching-immobilization of several type I receptors in the absence or presence of ligands with fluorescence recovery after photobleaching (FRAP) measurements on the lateral diffusion of an activin type II receptor, ACVR2A, to demonstrate the principle of competition between type I receptors for ACVR2. Our results show that ACVR2A can form stable heteromeric complexes with ALK4 (an activin type I receptor), as well as with several BMP type I receptors (ALK2/3/6). Of note, ALK4 and the BMP type I receptors competed for binding ACVR2A. To assess the implications of this competition for signaling output, we first validated that in our cell model system (U2OS cells), ACVR2/ALK4 transduce ActA signaling to Smad2/3, while BMP9 signaling to Smad1/5/8 employ ACVR2/ALK2 or ACVR2/ALK3. By combining ligand stimulation with overexpression of a competing type I receptor, we showed that differential complex formation of distinct type I receptors with a common type II receptor balances the signaling to the two Smad branches.

Conclusions

Different type I receptors that signal to distinct Smad pathways (Smad2/3 vs. Smad1/5/8) compete for binding to common activin type II receptors. This provides a novel mechanism to balance signaling between Smad2/3 and Smad1/5/8.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01252-z.

The Bright and the Dark Side of TGF-β Signaling in Hepatocellular Carcinoma: Mechanisms, Dysregulation, and Therapeutic Implications

Simple Summary

Transforming growth factor β (TGF-β) signaling is a preeminent regulator of diverse cellular and physiological processes. Frequent dysregulation of TGF-β signaling has been implicated in cancer. In hepatocellular carcinoma (HCC), the most prevalent form of primary liver cancer, the autocrine and paracrine effects of TGF-β have paradoxical implications. While acting as a potent tumor suppressor pathway in the early stages of malignancy, TGF-β diverts to a promoter of tumor progression in the late stages, reflecting its bright and dark natures, respectively. Within this context, targeting TGF-β represents a promising therapeutic option for HCC treatment. We discuss here the molecular properties of TGF-β signaling in HCC, attempting to provide an overview of its effects on tumor cells and the stroma. We also seek to evaluate the dysregulation mechanisms that mediate the functional switch of TGF-β from a tumor suppressor to a pro-tumorigenic signal. Finally, we reconcile its biphasic nature with the therapeutic implications.

Abstract

Hepatocellular carcinoma (HCC) is associated with genetic and nongenetic aberrations that impact multiple genes and pathways, including the frequently dysregulated transforming growth factor β (TGF-β) signaling pathway. The regulatory cytokine TGF-β and its signaling effectors govern a broad spectrum of spatiotemporally regulated molecular and cellular responses, yet paradoxically have dual and opposing roles in HCC progression. In the early stages of tumorigenesis, TGF-β signaling enforces profound tumor-suppressive effects, primarily by inducing cell cycle arrest, cellular senescence, autophagy, and apoptosis. However, as the tumor advances in malignant progression, TGF-β functionally switches to a pro-tumorigenic signal, eliciting aggressive tumor traits, such as epithelial–mesenchymal transition, tumor microenvironment remodeling, and immune evasion of cancer cells. On this account, the inhibition of TGF-β signaling is recognized as a promising therapeutic strategy for advanced HCC. In this review, we evaluate the functions and mechanisms of TGF-β signaling and relate its complex and pleiotropic biology to HCC pathophysiology, attempting to provide a detailed perspective on the molecular determinants underlying its functional diversion. We also address the therapeutic implications of the dichotomous nature of TGF-β signaling and highlight the rationale for targeting this pathway for HCC treatment, alone or in combination with other agents.

The Role and Research Progress of Inhibitor of Differentiation 1 in Atherosclerosis

Inhibitor of differentiation 1 has a helix-loop-helix (HLH) structure, belongs to a class of molecules known as the HLH trans-acting factor family, and plays an important role in advancing the cell cycle, promoting cell proliferation and inhibiting cell differentiation. Recent studies have confirmed that inhibitor of differentiation 1 plays an important role in the endothelial-mesenchymal transition of vascular endothelial cells, angiogenesis, reendothelialization after injury, and the formation and rupture of atherosclerotic plaques. An in-depth understanding of the role of inhibitor of differentiation 1 in atherosclerosis will provide new ideas and strategies for the treatment of related diseases.

Multiple roles of mothers against decapentaplegic homolog 4 in tumorigenesis, stem cells, drug resistance, and cancer therapy

The transforming growth factor (TGF)-β signaling pathway controls many cellular processes, including proliferation, differentiation, and apoptosis. Abnormalities in the TGF-β signaling pathway and its components are closely related to the occurrence of many human diseases, including cancer. Mothers against decapentaplegic homolog 4 (Smad4), also known as deleted in pancreatic cancer locus 4, is a typical tumor suppressor candidate gene locating at q21.1 of human chromosome 18 and the common mediator of the TGF-β/Smad and bone morphogenetic protein/Smad signaling pathways. It is believed that Smad4 inactivation correlates with the development of tumors and stem cell fate decisions. Smad4 also interacts with cytokines, miRNAs, and other signaling pathways, jointly regulating cell behavior. However, the regulatory function of Smad4 in tumorigenesis, stem cells, and drug resistance is currently controversial. In addition, Smad4 represents an attractive therapeutic target for cancer. Elucidating the specific role of Smad4 is important for understanding the mechanism of tumorigenesis and cancer treatment. Here, we review the identification and characterization of Smad4, the canonical TGF-β/Smad pathway, as well as the multiple roles of Smad4 in tumorigenesis, stem cells, and drug resistance. Furthermore, we provide novel insights into the prospects of Smad4-targeted cancer therapy and the challenges that it will face in the future.

Complex Formation Among TGF-β Receptors in Live Cell Membranes Measured by Patch-FRAP

Signaling by receptors from the transforming growth factor-β (TGF-β) superfamily plays critical roles in multiple physiological and pathological processes. Their signaling requires complex formation between type I and type II receptors with Ser/Thr kinase activity, whereby the type II receptor phosphorylates and activates the relevant type I receptor(s), which transduces downstream signaling. It is therefore important to study complex formation among receptors from this family. In the current chapter, we use the type I (ALK5) and type II TGF-β receptors (TβRI and TβRII) as an example for measuring complex formation among cell-surface receptors in live cells by patch-FRAP, a variation of fluorescence recovery after photobleaching (FRAP).

Activation and Role of Astrocytes in Ischemic Stroke

Ischemic stroke refers to the disorder of blood supply of local brain tissue caused by various reasons. It has high morbidity and mortality worldwide. Astrocytes are the most abundant glial cells in the central nervous system (CNS). They are responsible for the homeostasis, nutrition, and protection of the CNS and play an essential role in many nervous system diseases’ physiological and pathological processes. After stroke injury, astrocytes are activated and play a protective role through the heterogeneous and gradual changes of their gene expression, morphology, proliferation, and function, that is, reactive astrocytes. However, the position of reactive astrocytes has always been a controversial topic. Many studies have shown that reactive astrocytes are a double-edged sword with both beneficial and harmful effects. It is worth noting that their different spatial and temporal expression determines astrocytes’ various functions. Here, we comprehensively review the different roles and mechanisms of astrocytes after ischemic stroke. In addition, the intracellular mechanism of astrocyte activation has also been involved. More importantly, due to the complex cascade reaction and action mechanism after ischemic stroke, the role of astrocytes is still difficult to define. Still, there is no doubt that astrocytes are one of the critical factors mediating the deterioration or improvement of ischemic stroke.

Akt acts as a switch for GPCR transactivation of the TGF-β receptor type 1

Transforming growth factor (TGF)-β signalling commences with the engagement of TGF-β ligand to cell surface TGF-β receptors (TGFBR) stimulating Smad2 carboxyl-terminal phosphorylation (phospho-Smad2C) and downstream biological responses. In several cell models, G protein-coupled receptors (GPCRs) transactivate the TGF-β receptors type-1 (TGFBR1) leading to phospho-Smad2C, however, we have recently published that in keratinocytes thrombin did not transactivate the TGFBR1. The bulk of TGFBRs reside in the cytosol and in response to protein kinase B (Akt phosphorylation) can translocate to the cell surface increasing the cell's responsiveness to TGF-β. In this study, we investigate the role of Akt in GPCR transactivation of the TGFBR1. We demonstrate that angiotensin II and thrombin do not phosphorylate Smad2C in human vascular smooth muscle cells and in keratinocytes respectively. We used Akt agonist, SC79 to sensitise the cells to Akt and observed that Ang II and thrombin phosphorylate Smad2C via Akt/AS160-dependent pathways. We show that SC79 rapidly translocates TGFBRs to the cell surface thus increasing the cell's response to the GPCR agonist. These findings highlight novel mechanistic insight for the role of Akt in GPCR transactivation of the TGFBR1.

Tetrahedral framework nucleic acids promote the biological functions and related mechanism of synovium-derived mesenchymal stem cells and show improved articular cartilage regeneration activity in situ

Many recent studies have shown that joint-resident mesenchymal stem cells (MSCs) play a vital role in articular cartilage (AC) in situ regeneration. Specifically, synovium-derived MSCs (SMSCs), which have strong chondrogenic differentiation potential, may be the main driver of cartilage repair. However, both the insufficient number of MSCs and the lack of an ideal regenerative microenvironment in the defect area will seriously affect the regeneration of AC. Tetrahedral framework nucleic acids (tFNAs), notable novel nanomaterials, are considered prospective biological regulators in biomedical engineering. Here, we aimed to explore whether tFNAs have positive effects on AC in situ regeneration and to investigate the related mechanism. The results of in vitro experiments showed that the proliferation and migration of SMSCs were significantly enhanced by tFNAs. In addition, tFNAs, which were added to chondrogenic induction medium, were shown to promote the chondrogenic capacity of SMSCs by increasing the phosphorylation of Smad2/3. In animal models, the injection of tFNAs improved the therapeutic outcome of cartilage defects compared with that of the control treatments without tFNAs. In conclusion, this is the first report to demonstrate that tFNAs can promote the chondrogenic differentiation of SMSCs in vitro and enhance AC regeneration in vivo, indicating that tFNAs may become a promising therapeutic for AC regeneration.

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Tetrahedral framework nucleic acids (tFNAs) can promote SMSCs proliferation by activating the Wnt/β-catenin pathway.

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tFNAs can promote SMSCs migration in vitro and vivo.

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tFNAs can promote SMSCs chondrogenic differentiation by regulating the TGF/Smad2/3 signaling pathway.

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tFNAs show improved articular cartilage in situ regeneration activity in vivo.

Identification of a TGF-β/SMAD/lnc-UTGF positive feedback loop and its role in hepatoma metastasis

Aberrant activation of the TGF-β/SMAD signaling pathway is often observed in hepatocellular carcinoma (HCC). Whether lncRNA regulates the TGF-β/SMAD signaling remains largely unknown. Here, we identified an oncogenic lncRNA that was upregulated in HCC and was transcriptionally induced by TGF-β (named lnc-UTGF, lncRNA upregulated by TGF-β). Upon TGF-β stimulation, SMAD2/3 bound to the lnc-UTGF promoter and activated lnc-UTGF expression. In turn, the TGF-β/SMAD signaling was augmented by overexpressing lnc-UTGF, but was inhibited by silencing lnc-UTGF. Mechanism investigations revealed that lnc-UTGF interacted with the mRNAs of SMAD2 and SMAD4 via complementary base-pairing, resulting in enhanced stability of SMAD2/4 mRNAs. These data suggest a novel TGF-β/SMAD/lnc-UTGF positive feedback circuitry. Subsequent gain- and loss-of-function analyses disclosed that lnc-UTGF promoted the migration and invasion of hepatoma cells, and this effect of lnc-UTGF was attenuated by repressing SMAD2/4 expression or by mutating the SMAD2/4-binding sites in lnc-UTGF. Studies using mouse models further confirmed that in vivo metastasis of hepatoma xenografts was inhibited by silencing lnc-UTGF, but was enhanced by ectopic expression of lnc-UTGF. The lnc-UTGF level was positively correlated with the SMAD2/4 levels in xenografts. Consistently, we detected an association of lnc-UTGF upregulation with increase of SMAD2, SMAD4, and their metastasis effector SNAIL1 in human HCC. And high lnc-UTGF level was also significantly associated with enhanced metastasis potential, advanced TNM stages, and worse recurrence-free survival. Conclusion: there exists a lnc-UTGF-mediated positive feedback loop of the TGF-β signaling and its deregulation promotes hepatoma metastasis. These findings may provide a new therapeutic target for HCC metastasis.

Epigenetic Modulation of Class-Switch DNA Recombination to IgA by miR-146a Through Downregulation of Smad2, Smad3 and Smad4

IgA is the predominant antibody isotype at intestinal mucosae, where it plays a critical role in homeostasis and provides a first line of immune protection. Dysregulation of IgA production, however, can contribute to immunopathology, particularly in kidneys in which IgA deposition can cause nephropathy. Class-switch DNA recombination (CSR) to IgA is directed by TGF-β signaling, which activates Smad2 and Smad3. Activated Smad2/Smad3 dimers are recruited together with Smad4 to the IgH α locus Iα promoter to activate germline Iα-Cα transcription, the first step in the unfolding of CSR to IgA. Epigenetic factors, such as non-coding RNAs, particularly microRNAs, have been shown to regulate T cells, dendritic cells and other immune elements, as well as modulate the antibody response, including CSR, in a B cell-intrinsic fashion. Here we showed that the most abundant miRNA in resting B cells, miR-146a targets Smad2, Smad3 and Smad4 mRNA 3'UTRs and keeps CSR to IgA in check in resting B cells. Indeed, enforced miR-146a expression in B cells aborted induction of IgA CSR by decreasing Smad levels. By contrast, upon induction of CSR to IgA, as directed by TGF-β, B cells downregulated miR-146a, thereby reversing the silencing of Smad2, Smad3 and Smad4, which, once expressed, led to recruitment of Smad2, Smad3 and Smad4 to the Iα promoter for activation of germline Iα-Cα transcription. Deletion of miR-146a in miR-146a-/- mice significantly increased circulating levels of steady state total IgA, but not IgM, IgG or IgE, and heightened the specific IgA antibody response to OVA. In miR-146a-/- mice, the elevated systemic IgA levels were associated with increased IgA+ B cells in intestinal mucosae, increased amounts of fecal free and bacteria-bound IgA as well as kidney IgA deposition, a hallmark of IgA nephropathy. Increased germline Iα-Cα transcription and CSR to IgA in miR-146a-/- B cells in vitro proved that miR-146a-induced Smad2, Smad3 and Smad4 repression is B cell intrinsic. The B cell-intrinsic role of miR-146a in the modulation of CSR to IgA was formally confirmed in vivo by construction and OVA immunization of mixed bone marrow μMT/miR-146a-/- chimeric mice. Thus, by inhibiting Smad2, Smad3 and Smad4 expression, miR-146a plays an important and B cell intrinsic role in modulation of CSR to IgA and the IgA antibody response.

Melatonin Promotes the Therapeutic Effect of Mesenchymal Stem Cells on Type 2 Diabetes Mellitus by Regulating TGF-β Pathway

Abundant evidence proves the therapeutic effect of adipose-derived mesenchymal stem cells (ADMSCs) in the treatment of diabetes mellitus. However, the problems have not been solved that viability of ADMSCs were inconsistent and the cells quickly undergo senescence after in vitro cell culture. In addition, the therapeutic effect of ADMSCs is still not satisfactory. In this study, melatonin (MLT) was added to canine ADMSC culture medium, and the treated cells were used to treat type 2 diabetes mellitus (T2DM). Our research reveals that adding MLT to ADMSC culture medium can promote the viability of ADMSCs. This effect depends on the binding of MLT and MLT receptors, which activates the transforming growth factor β (TGF-β) pathway and then changes the cell cycle of ADMSCs and improves the viability of ADMSCs. Since ADMSCs were found to be used to treat T2DM by anti-inflammatory and anti-endoplasmic reticulum (ER) stress capabilities, our data demonstrate that MLT augment several effects of ADMSCs in remission hyperglycemia, insulin resistance, and liver glycogen metabolism in T2DM patients. This suggest that ADMSCs and MLT-ADMSCs is safe and vabulable for pet clinic.

SMAD2 regulates testicular development and testosterone synthesis in Hu sheep

The SMAD protein family plays crucial roles in reproduction as a downstream target genes of the TGFβ signaling pathway. Many studies have focused on the expression change exploration of SMADs during testicular development and investigation of SMAD2 in hormone synthesis regulation. However, little attention has been given to determining the regulatory mechanism of SMADs in sheep testes. In the present study, we first detected SMAD mRNA expression levels in three-month-old (3 M), six-month-old (6 M), nine-month-old (9 M) and two-year-old (2Y) sheep testes. Different SMADs showed various expression patterns. In addition, the subcellular localization of SMAD2 was also analyzed, and Sertoli cells (SCs), Leydig cells (LCs) and spermatogonia presented mainly positive staining. Protein and nucleic acid sequence alignment showed that the SMAD2 gene was extremely homologous between various species. SMAD2 interference RNA was transfected into sheep LCs to examine the cell proliferation and hormone levels. The testosterone level was significantly decreased, and cell proliferation efficiency presented the same trend (P < 0.05). Moreover, SMAD2 downregulation promoted cell apoptosis (P < 0.05) and changed the cell cycle. In total, our results revealed that downregulating the expression of SMAD2 can effectively inhibit testosterone levels by affecting cell proliferation and apoptosis.

Airway Remodeling in Feline Lungs

Airway remodeling encompass structural changes that occur as the result of chronic injury and lead to persistently altered airway structure and function. Although this process is known in several human respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD), airway remodeling is poorly characterized in the feline counterpart. In this study, we describe the spontaneous pulmonary changes in 3 cats paralleling the airway remodeling reported in humans. We observed airway smooth muscle cells (ASMCs) hyperplasia (peribronchial and interstitial), airway subepithelial and interstitial fibrosis, and vascular remodeling by increased number of vessels in the bronchial submucosa. The hyperplastic ASMCs co-expressed α-SMA, vimentin and desmin suggesting that vimentin, which is not normally expressed by ASMCs, may play a role in airway thickening, and remodeling. ASMCs had strong cytoplasmic expression of TGFβ-1, which is known to contribute to tissue remodeling in asthma and in various bronchial and interstitial lung diseases, suggesting its involvement in the pathogenesis of ASMCs hyperplasia. Our findings provide histologic evidence of airway remodeling in cats. Further studies on larger caseloads are needed to support our conclusions on the value of this feline condition as an animal model for nonspecific airway remodeling in humans.

Understanding the Renal Fibrotic Process in Leptospirosis

Leptospirosis is a neglected infectious disease caused by pathogenic species of the genus Leptospira. The acute disease is well-described, and, although it resembles other tropical diseases, it can be diagnosed through the use of serological and molecular methods. While the chronic renal disease, carrier state, and kidney fibrosis due to Leptospira infection in humans have been the subject of discussion by researchers, the mechanisms involved in these processes are still overlooked, and relatively little is known about the establishment and maintenance of the chronic status underlying this infectious disease. In this review, we highlight recent findings regarding the cellular communication pathways involved in the renal fibrotic process, as well as the relationship between renal fibrosis due to leptospirosis and CKD/CKDu.

A Novel Splice Variant of Human TGF-β Type II Receptor Encodes a Soluble Protein and Its Fc-Tagged Version Prevents Liver Fibrosis in vivo

We describe, for the first time, a new splice variant of the human TGF-β type II receptor (TβRII). The new transcript lacks 149 nucleotides, resulting in a frameshift and the emergence of an early stop codon, rendering a truncated mature protein of 57 amino acids. The predicted protein, lacking the transmembrane domain and with a distinctive 13-amino-acid stretch at its C-terminus, was named TβRII-Soluble Endogenous (TβRII-SE). Binding predictions indicate that the novel 13-amino-acid stretch interacts with all three TGF-β cognate ligands and generates a more extensive protein–protein interface than TβRII. TβRII-SE and human IgG1 Fc domain were fused in frame in a lentiviral vector (Lv) for further characterization. With this vector, we transduced 293T cells and purified TβRII-SE/Fc by A/G protein chromatography from conditioned medium. Immunoblotting revealed homogeneous bands of approximately 37 kDa (reduced) and 75 kDa (non-reduced), indicating that TβRII-SE/Fc is secreted as a disulfide-linked homodimer. Moreover, high-affinity binding of TβRII-SE to the three TGF-β isoforms was confirmed by surface plasmon resonance (SPR) analysis. Also, intrahepatic delivery of Lv.TβRII-SE/Fc in a carbon tetrachloride-induced liver fibrosis model revealed amelioration of liver injury and fibrosis. Our results indicate that TβRII-SE is a novel member of the TGF-β signaling pathway with distinctive characteristics. This novel protein offers an alternative for the prevention and treatment of pathologies caused by the overproduction of TGF-β ligands.

Identification, Molecular Characterization, and Tissue Expression Profiles of Three Smad Genes from Water Buffalo (Bubalus bubalis)

Smads are involved in a variety of biological activities by mediating bone morphogenetic protein (BMP) signals. The full-length coding sequences (CDSs) of buffalo Smads 1, 4, and 5 were isolated and identified through RT-PCR in this study. Their lengths are 1398 bp, 1662 bp, and 1398 bp, respectively. In silico analysis showed that their transcriptional region structures, as well as their amino acid sequences, physicochemical characteristics, motifs, conserved domains, and three-dimensional structures of their encoded proteins are highly consistent with their counterparts in the species of Bovidae. The three Smad proteins are all hydrophilic without the signal peptides and transmembrane regions. Each of them has an MH1 domain and an MH2 domain. A nuclear localization sequence was found in the MH1 domain of buffalo Smads 1 and 5. Prediction showed that the function of the three Smads is mainly protein binding, and they can interact with BMPs and their receptors. The three genes were expressed in all 10 buffalo tissues assayed, and their expression in the mammary gland, gonad, and spleen was relatively high. The results here indicate that the three buffalo Smads may be involved in the transcriptional regulation of genes in a variety of tissues.

Endoglin deficiency impairs VEGFR2 but not FGFR1 or TIE2 activation and alters VEGF-mediated cellular responses in human primary endothelial cells

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disease characterized by vascular dysplasia. Mutations of the endoglin (ENG) gene that encodes a co-receptor of the transforming growth factor β1 signaling pathway cause type I HHT. ENG is primarily expressed in endothelial cells (ECs), but its interaction with other key angiogenic pathways to control angiogenesis has not been well addressed. The aim of this study is to investigate ENG interplay with VEGFR2, FGFR1 and TIE2 in primary human ECs. ENG was knocked-down with siRNA in human umbilical vein ECs (HUVECs) and human lung microvascular ECs (HMVEC-L). Gene expression was measured by RT-qPCR and Western blotting. Cell signaling pathway activation was analyzed by detecting phosphor-ERK and phosphor-AKT levels. Cell migration and apoptosis were assessed using the Boyden chamber assay and the CCK-8 Kit, respectively. Loss of ENG in HUVECs led to significantly reduced expression of VEGFR2 but not TIE2 or FGFR1, which was also confirmed in HMVEC-L. HUVECs lacking ENG had significantly lower levels of active Rac1 and a substantial reduction of the transcription factor Sp1, an activator of VEGFR2 transcription, in nuclei. Furthermore, VEGF- but not bFGF- or angiopoietin-1-induced phosphor-ERK and phosphor-AKT were suppressed in ENG deficient HUVECs. Functional analysis revealed that ENG knockdown inhibited cell migratory but enhanced anti-apoptotic activity induced by VEGF. In contrast, bFGF, angiopoietin-1 and -2 induced HUVEC migration and anti-apoptotic activities were not affected by ENG knockdown. In conclusion, ENG deficiency alters the VEGF/VEGFR2 pathway, which may play a role in HHT pathogenesis.

Canonical TGFβ Signaling and Its Contribution to Endometrial Cancer Development and Progression-Underestimated Target of Anticancer Strategies

Endometrial cancer is one of the leading gynecological cancers diagnosed among women in their menopausal and postmenopausal age. Despite the progress in molecular biology and medicine, no efficient and powerful diagnostic and prognostic marker is dedicated to endometrial carcinogenesis. The canonical TGFβ pathway is a pleiotropic signaling cascade orchestrating a variety of cellular and molecular processes, whose alterations are responsible for carcinogenesis that originates from different tissue types. This review covers the current knowledge concerning the canonical TGFβ pathway (Smad-dependent) induced by prototypical TGFβ isoforms and the involvement of pathway alterations in the development and progression of endometrial neoplastic lesions. Since Smad-dependent signalization governs opposed cellular processes, such as growth arrest, apoptosis, tumor cells growth and differentiation, as well as angiogenesis and metastasis, TGFβ cascade may act both as a tumor suppressor or tumor promoter. However, the final effect of TGFβ signaling on endometrial cancer cells depends on the cancer disease stage. The multifunctional role of the TGFβ pathway indicates the possible utilization of alterations in the TGFβ cascade as a potential target of novel anticancer strategies.

Effect of ciglitazone on adipogenic transdifferentiation of bovine skeletal muscle satellite cells

Ciglitazone is a member of the thiazolidinedione family, and specifically binds to peroxisome proliferator-activated receptor-γ (PPARγ), thereby promoting adipocyte differentiation. We hypothesized that ciglitazone as a PPARγ ligand in the absence of an adipocyte differentiation cocktail would increase adiponectin and adipogenic gene expression in bovine satellite cells (BSC). Muscle-derived BSCs were isolated from six, 18-month-old Yanbian Yellow Cattle. The BSC were cultured for 96 h in differentiation medium containing 5 µM ciglitazone (CL), 10 µM ciglitazone (CM), or 20 µM ciglitazone (CH). Control (CON) BSC were cultured only in a differentiation medium (containing 2% horse serum). The presence of myogenin, desmin, and paired box7 (Pax7) proteins was confirmed in the BSC by immunofluorescence staining. The CL, CM, and CH treatments produced higher concentrations of triacylglycerol and lipid droplet accumulation in myotubes than those of the CON treatment. Ciglitazone treatments significantly increased the relative expression of PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα), C/EBPβ, fatty acid synthase, stearoyl-CoA desaturase, and perilipin 2. Ciglitazone treatments increased gene expression of Pax3 and Pax7 and decreased expression of myogenic differentiation-1, myogenin, myogenic regulatory factor-5, and myogenin-4 (p < 0.01). Adiponectin concentration caused by ciglitazone treatments was significantly greater than CON (p < 0.01). RNA sequencing showed that 281 differentially expressed genes (DEGs) were found in the treatments of ciglitazone. DEGs gene ontology (GO) analysis showed that the top 10 GO enrichment significantly changed the biological processes such as protein trimerization, negative regulation of cell proliferation, adipocytes differentiation, and cellular response to external stimulus. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that DEGs were involved in the p53 signaling pathway, PPAR signaling pathway, biosynthesis of amino acids, tumor necrosis factor signaling pathway, non-alcoholic fatty liver disease, PI3K-Akt signaling pathway, and Wnt signaling pathway. These results indicate that ciglitazone acts as PPARγ agonist, effectively increases the adiponectin concentration and adipogenic gene expression, and stimulates the conversion of BSC to adipocyte-like cells in the absence of adipocyte differentiation cocktail.

FGFR3 phosphorylates EGFR to promote cisplatin-resistance in ovarian cancer

Ovarian cancer is a deadly gynecologic cancer, and the majority of patients with ovarian cancer experience relapse after traditional treatment. Cisplatin (DDP) is a common chemotherapeutic drug for ovarian cancer, but many patients acquire DDP-resistance after treatment with long-term chemotherapy. The mechanisms of drug-resistance in ovarian cancer are not clear, and we thus aim to investigate novel targets for DDP-resistant ovarian cancer. Differential analysis, KEGG pathway enrichment and protein interaction networks were employed to identify the key genes related to DDP-resistance in ovarian cancer. Subsequently, cell viability, apoptosis and migration were measured to assess the effect of fibroblast growth factor receptor 3 (FGFR3) on DDP-resistance. Further, Pearson correlation analysis and co-expression analysis were used to explore the downstream pathways of FGFR3, and the function of FGFR3 and its downstream targets were further demonstrated by in vitro and nude mice experiments. FGFR3 were expressed at high levels in DDP-resistant ovarian cancer cells. FGFR3 silencing suppressed the activation of PI3K/AKT pathway and impeded the drug-resistance and development of tumor cells. Afterwards, we found that FGFR3 was co-expressed with epidermal growth factor receptor (EGFR). FGFR3 overexpression elevated EGFR phosphorylation and activated PI3K/AKT signaling. Furthermore, in nude mice, silencing FGFR3 and inhibiting EGFR phosphorylation were observed to promote the therapeutic effect of DDP. In conclusion, FGFR3 overexpression enhances DDP-resistance of ovarian cancer by promoting EGFR phosphorylation and further activating PI3K/AKT pathway. This study may offer promising targets for DDP-resistant ovarian cancer.

MicroRNAs as biomarkers and perspectives in the therapy of pancreatic cancer

Pancreatic cancer is considered as one of the most aggressive tumor types, representing over 45,750 mortality cases annually in the USA solely. The aggressive nature and late identification of pancreatic cancer, combined with the restrictions of existing chemotherapeutics, present the mandatory need for the advancement of novel treatment systems. Ongoing reports have shown an important role of microRNAs (miRNAs) in the initiation, migration, and metastasis of malignancies. Besides, abnormal transcriptional levels of miRNAs have regularly been related with etiopathogenesis of pancreatic malignancy, underlining the conceivable utilization of miRNAs in the management of pancreatic disease patients. In this review article, we give a concise outline of molecular pathways involved in etiopathogenesis of pancreatic cancer patients as well as miRNA implications in pancreatic cancer patients. Ensuing sections describe the involvement of miRNAs in the diagnosis, prognosis, and therapy of pancreatic cancer patients. The involvement of miRNAs in the chemoresistance of pancreatic cancers was also discussed. End area portrays the substance of survey with future headings.

A comparative study of mesenchymal stem cell transplantation and NTG-101 molecular therapy to treat degenerative disc disease

Cellular replacement therapy using mesenchymal stem cells (MSCs) and/or the delivery of growth factors are at the forefront of minimally invasive biological treatment options for Degenerative Disc Disease (DDD). In this study, we compared the therapeutic potential of a novel drug candidate, NTG-101 to MSCs, including rat cartilage derived stem cells (rCDSCs), bone marrow stem cells (rBMSCs) and human Umbilical Cord Derived Mesenchymal Stem Cells (hUCMSCs) for the treatment of DDD. We induced DDD using a validated image-guided needle puncture injury in rat-tail IVDs. Ten weeks post-injury, animals were randomized and injected with MSCs, NTG-101 or vehicle. At the end of the study, histological analysis of the IVD-Nucleus Pulposus (NPs) injected with NTG-101 or rCDSCs showed a healthy or mild degenerative phenotype in comparison to vehicle controls. Immunohistochemical analysis revealed strong expression of aggrecan, collagen 2, brachyury and Oct4 in IVD-NPs injected with NTG-101. Our results also demonstrated suppression of inflammation induced p38 and NFκB resulting in inhibition of catabolic genes, but activation of Smad-2/3, Erk-1/2 and Akt-dependent signaling inducing anabolic genes in IVD-NP on treatment with NTG-101. In conclusion, a single injection of NTG-101 into the degenerative disc demonstrated superior benefits compared to stem cell transplantation.

Origins, potency, and heterogeneity of skeletal muscle fibro-adipogenic progenitors-time for new definitions

Striated muscle is a highly plastic and regenerative organ that regulates body movement, temperature, and metabolism-all the functions needed for an individual's health and well-being. The muscle connective tissue's main components are the extracellular matrix and its resident stromal cells, which continuously reshape it in embryonic development, homeostasis, and regeneration. Fibro-adipogenic progenitors are enigmatic and transformative muscle-resident interstitial cells with mesenchymal stem/stromal cell properties. They act as cellular sentinels and physiological hubs for adult muscle homeostasis and regeneration by shaping the microenvironment by secreting a complex cocktail of extracellular matrix components, diffusible cytokines, ligands, and immune-modulatory factors. Fibro-adipogenic progenitors are the lineage precursors of specialized cells, including activated fibroblasts, adipocytes, and osteogenic cells after injury. Here, we discuss current research gaps, potential druggable developments, and outstanding questions about fibro-adipogenic progenitor origins, potency, and heterogeneity. Finally, we took advantage of recent advances in single-cell technologies combined with lineage tracing to unify the diversity of stromal fibro-adipogenic progenitors. Thus, this compelling review provides new cellular and molecular insights in comprehending the origins, definitions, markers, fate, and plasticity of murine and human fibro-adipogenic progenitors in muscle development, homeostasis, regeneration, and repair.

The TGF-β Pathway: A Pharmacological Target in Hepatocellular Carcinoma?

Transforming Growth Factor-beta (TGF-β) superfamily members are essential for tissue homeostasis and consequently, dysregulation of their signaling pathways contributes to the development of human diseases. In the liver, TGF-β signaling participates in all the stages of disease progression from initial liver injury to hepatocellular carcinoma (HCC). During liver carcinogenesis, TGF-β plays a dual role on the malignant cell, behaving as a suppressor factor at early stages, but contributing to later tumor progression once cells escape from its cytostatic effects. Moreover, TGF-β can modulate the response of the cells forming the tumor microenvironment that may also contribute to HCC progression, and drive immune evasion of cancer cells. Thus, targeting the TGF-β pathway may constitute an effective therapeutic option for HCC treatment. However, it is crucial to identify biomarkers that allow to predict the response of the tumors and appropriately select the patients that could benefit from TGF-β inhibitory therapies. Here we review the functions of TGF-β on HCC malignant and tumor microenvironment cells, and the current strategies targeting TGF-β signaling for cancer therapy. We also summarize the clinical impact of TGF-β inhibitors in HCC patients and provide a perspective on its future use alone or in combinatorial strategies for HCC treatment.

Regulation of metabolic homeostasis by the TGF-β superfamily receptor ALK7

ALK7 (Activin receptor-like kinase 7) is a member of the TGF-β receptor superfamily predominantly expressed by cells and tissues involved in endocrine functions, such as neurons of the hypothalamus and pituitary, pancreatic β-cells and adipocytes. Recent studies have begun to delineate the processes regulated by ALK7 in these tissues and how these become integrated with the homeostatic regulation of mammalian metabolism. The picture emerging indicates that ALK7's primary function in metabolic regulation is to limit catabolic activities and preserve energy. Aside of the hypothalamic arcuate nucleus, the function of ALK7 elsewhere in the brain, particularly in the cerebellum, where it is abundantly expressed, remains to be elucidated. Although our understanding of the basic molecular events underlying ALK7 signaling has benefited from the vast knowledge available on TGF-β receptor mechanisms, how these connect to the physiological functions regulated by ALK7 in different cell types is still incompletely understood. Findings of missense and nonsense variants in the Acvr1c gene, encoding ALK7, of some mouse strains and human subjects indicate a tolerance to ALK7 loss of function. Recent discoveries suggest that specific inhibitors of ALK7 may have therapeutic applications in obesity and metabolic syndrome without overt adverse effects.

Signaling Pathways That Regulate the Crustacean Molting Gland

A pair of Y-organs (YOs) are the molting glands of decapod crustaceans. They synthesize and secrete steroid molting hormones (ecdysteroids) and their activity is controlled by external and internal signals. The YO transitions through four physiological states over the molt cycle, which are mediated by molt-inhibiting hormone (MIH; basal state), mechanistic Target of Rapamycin Complex 1 (mTORC1; activated state), Transforming Growth Factor-β (TGFβ)/Activin (committed state), and ecdysteroid (repressed state) signaling pathways. MIH, produced in the eyestalk X-organ/sinus gland complex, inhibits the synthesis of ecdysteroids. A model for MIH signaling is organized into a cAMP/Ca2+-dependent triggering phase and a nitric oxide/cGMP-dependent summation phase, which maintains the YO in the basal state during intermolt. A reduction in MIH release triggers YO activation, which requires mTORC1-dependent protein synthesis, followed by mTORC1-dependent gene expression. TGFβ/Activin signaling is required for YO commitment in mid-premolt. The YO transcriptome has 878 unique contigs assigned to 23 KEGG signaling pathways, 478 of which are differentially expressed over the molt cycle. Ninety-nine contigs encode G protein-coupled receptors (GPCRs), 65 of which bind a variety of neuropeptides and biogenic amines. Among these are putative receptors for MIH/crustacean hyperglycemic hormone neuropeptides, corazonin, relaxin, serotonin, octopamine, dopamine, allatostatins, Bursicon, ecdysis-triggering hormone (ETH), CCHamide, FMRFamide, and proctolin. Contigs encoding receptor tyrosine kinase insulin-like receptor, epidermal growth factor (EGF) receptor, and fibroblast growth factor (FGF) receptor and ligands EGF and FGF suggest that the YO is positively regulated by insulin-like peptides and growth factors. Future research should focus on the interactions of signaling pathways that integrate physiological status with environmental cues for molt control.

Photoactivation of TGFβ/SMAD signaling pathway ameliorates adult hippocampal neurogenesis in Alzheimer's disease model

Background

Adult hippocampal neurogenesis (AHN) is restricted under the pathological conditions of neurodegenerative diseases, especially in Alzheimer’s disease (AD). The drop of AHN reduces neural circuit plasticity, resulting in the decrease of the generation of newborn neurons in dentate gyrus (DG), which makes it difficult to recover from learning/memory dysfunction in AD, therefore, it is imperative to find a therapeutic strategy to promote neurogenesis and clarify its underlying mechanism involved.

Methods

Amyloid precursor protein/presenilin 1 (APP/PS1) mice were treated with photobiomodulation therapy (PBMT) for 0.1 mW/mm² per day in the dark for 1 month (10 min for each day). The neural stem cells (NSCs) were isolated from hippocampus of APP/PS1 transgenic mice at E14, and the cells were treated with PBMT for 0.667 mW/mm² in the dark (5 min for each time).

Results

In this study, photobiomodulation therapy (PBMT) is found to promote AHN in APP/PS1 mice. The latent transforming growth factor-β1 (LTGFβ1) was activated in vitro and in vivo during PBMT-induced AHN, which promoted the differentiation of hippocampal APP/PS1 NSCs into newborn neurons. In particular, behavioral experiments showed that PBMT enhanced the spatial learning/memory ability of APP/PS1 mice. Mechanistically, PBMT-stimulated reactive oxygen species (ROS) activates TGFβ/Smad signaling pathway to increase the interaction of the transcription factors Smad2/3 with Smad4 and competitively reduce the association of Smad1/5/9 with Smad4, thereby significantly upregulating the expression of doublecortin (Dcx)/neuronal class-III β-tubulin (Tuj1) and downregulating the expression of glial fibrillary acidic protein (GFAP). These in vitro effects were abrogated when eliminating ROS. Furthermore, specific inhibition of TGFβ receptor I (TGFβR I) attenuates the DNA-binding efficiency of Smad2/3 to the Dcx promotor triggered by PBMT.

Conclusion

Our study demonstrates that PBMT, as a viable therapeutic strategy, directs the adult hippocampal APP/PS1 NSCs differentiate towards neurons, which has great potential value for ameliorating the drop of AHN in Alzheimer’s disease mice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02399-2.

Insight into the role of multiple signaling pathways in regulating cancer stem cells of gynecologic cancers

Mounting evidence has demonstrated that a myriad of developmental signaling pathways, such as the Wnt, Notch, Hedgehog and Hippo, are frequently deregulated and play a critical role in regulating cancer stem cell (CSC) activity in human cancers, including gynecologic malignancies. In this review article, we describe an overview of various signaling pathways in human cancers. We further discuss the developmental roles how these pathways regulate CSCs from experimental evidences in gynecologic cancers. Moreover, we mention several compounds targeting CSCs in gynecologic cancers to enhance the treatment outcomes. Therefore, these signaling pathways might be the potential targets for developing targeted therapy in gynecologic cancers.

MicroRNA-503 Targets Mothers Against Decapentaplegic Homolog 7 Enhancing Hepatic Stellate Cell Activation and Hepatic Fibrosis

BACKGROUND

The hyper-accumulation of extracellular matrix (ECM) is the leading cause of hepatic fibrosis, and TGF-β-induced activation of hepatic stellate cells (HSCs) is the central event of hepatic fibrosis pathogenesis. The deregulation and dysfunction of miRNAs in hepatic fibrosis have been reported previously.

AIMS

To identify miRNA(s) playing a role in HSC activation and the underlying mechanism.

METHODS

We analyzed online microarray expression datasets from Gene Expression Omnibus (GEO) for differentially expressed miRNAs in hepatic fibrosis-related disease liver tissues, examined the specific effects of the candidate miRNA on TGF-β-induced HSC activation, and screened for the targets of the candidate miRNA in the TGF-β/SMAD signaling. Then, the predicted miRNA-mRNA binding, the specific effects of the target mRNA, and the dynamic effects of miRNA and mRNA on TGF-β-induced HSC activation were investigated.

RESULTS

The miR-503 expression was upregulated in TGF-β-activated HSCs. miR-503 overexpression enhanced, while miR-503 inhibition attenuated TGF-β-induced HSC proliferation and ECM accumulation in HSCs. miR-503 targeted SMAD7 to inhibit SMAD7 expression. SMAD7 knockdown also aggravated TGF-β-induced HSC proliferation and ECM accumulation in HSCs. The effects of miR-503 overexpression on TGF-β-induced HSC activation were partially reversed by SMAD7 overexpression. In CCl₄-induced hepatic fibrosis model in rats, miR-503 overexpression aggravated, whereas SMAD7 overexpression improved CCl₄-induced fibrotic changes in rats' liver tissues. The effects of miR-503 overexpression on CCl₄-induced fibrotic changes were partially reversed by SMAD7 overexpression.

CONCLUSION

miR-503 acts on HSC activation and hepatic fibrosis through SMAD7. The miR-503/SMAD7 axis enhances HSC activation and hepatic fibrosis through the TGF-β/SMAD pathway.

Targeting Nestin+ hepatic stellate cells ameliorates liver fibrosis by facilitating TβRI degradation

BACKGROUND & AIMS

Liver fibrosis is a wound healing response that arises from various aetiologies. The intermediate filament protein Nestin has been reported to participate in maintaining tissue homeostasis during wound healing responses. However, little is known about the role Nestin plays in liver fibrosis. This study investigated the function and precise regulatory network of Nestin during liver fibrosis.

METHODS

Nestin expression was assessed via immunostaining and quantitative real-time PCR (qPCR) in fibrotic/cirrhotic samples. The induction of Nestin expression by transforming growth factor beta (TGFβ)-Smad2/3 signalling was investigated through luciferase reporter assays. The functional role of Nestin in hepatic stellate cells (HSCs) was investigated by examining the pathway activity of profibrogenic TGFβ-Smad2/3 signalling and degradation of TGFβ receptor I (TβRI) after interfering with Nestin. The in vivo effects of knocking down Nestin were examined with an adeno-associated virus vector (serotype 6, AAV6) carrying short-hairpin RNA targeting Nestin in fibrotic mouse models.

RESULTS

Nestin was mainly expressed in activated HSCs and increased with the progression of liver fibrosis. The profibrogenic pathway TGFβ-Smad2/3 induced Nestin expression directly. Knocking down Nestin promoted caveolin 1-mediated TβRI degradation, resulting in TGFβ-Smad2/3 pathway impairment and reduced fibrosis marker expression in HSCs. In AAV6-treated murine fibrotic models, knocking down Nestin resulted in decreased levels of inflammatory infiltration, hepatocellular damage, and a reduced degree of fibrosis.

CONCLUSION

The expression of Nestin in HSCs was induced by TGFβ and positively correlated with the degree of liver fibrosis. Knockdown of Nestin decreased activation of the TGFβ pathway and alleviated liver fibrosis both in vitro and in vivo. Our data demonstrate a novel role of Nestin in controlling HSC activation in liver fibrosis.

LAY SUMMARY

Liver fibrosis has various aetiologies but represents a common process in chronic liver diseases that is associated with high morbidity and mortality. Herein, we demonstrate that the intermediate filament protein Nestin plays an essential profibrogenic role in liver fibrosis by forming a positive feedback loop with the TGFβ-Smad2/3 pathway, providing a potential therapeutic target for the treatment of liver fibrosis.

BFAR coordinates TGFβ signaling to modulate Th9-mediated cancer immunotherapy

TGFβ is essential for the generation of anti-tumor Th9 cells; on the other hand, it causes resistance against anti-tumor immunity. Despite recent progress, the underlying mechanism reconciling the double-edged effect of TGFβ signaling in Th9-mediated cancer immunotherapy remains elusive. Here, we find that TGFβ-induced down-regulation of bifunctional apoptosis regulator (BFAR) represents the key mechanism preventing the sustained activation of TGFβ signaling and thus impairing Th9 inducibility. Mechanistically, BFAR mediates K63-linked ubiquitination of TGFβR1 at K268, which is critical to activate TGFβ signaling. Thus, BFAR deficiency or K268R knock-in mutation suppresses TGFβR1 ubiquitination and Th9 differentiation, thereby inhibiting Th9-mediated cancer immunotherapy. More interestingly, BFAR-overexpressed Th9 cells exhibit promising therapeutic efficacy to curtail tumor growth and metastasis and promote the sensitivity of anti–PD-1–mediated checkpoint immunotherapy. Thus, our findings establish BFAR as a key TGFβ-regulated gene to fine-tune TGFβ signaling that causes Th9 induction insensitivity, and they highlight the translational potential of BFAR in promoting Th9-mediated cancer immunotherapy.

The role of SOCS proteins in the development of virus- induced hepatocellular carcinoma

Background

Liver cancer has become one of the most common cancers and has a high mortality rate. Hepatocellular carcinoma is one of the most common liver cancers, and its occurrence and development process are associated with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections.

Main body

The serious consequences of chronic hepatitis virus infections are related to the viral invasion strategy. Furthermore, the viral escape mechanism has evolved during long-term struggles with the host. Studies have increasingly shown that suppressor of cytokine signaling (SOCS) proteins participate in the viral escape process. SOCS proteins play an important role in regulating cytokine signaling, particularly the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. Cytokines stimulate the expression of SOCS proteins, in turn, SOCS proteins inhibit cytokine signaling by blocking the JAK-STAT signaling pathway, thereby achieving homeostasis. By utilizing SOCS proteins, chronic hepatitis virus infection may destroy the host’s antiviral responses to achieve persistent infection.

Conclusions

This review provides recent knowledge regarding the role of SOCS proteins during chronic hepatitis virus infection and provides some new ideas for the future treatment of chronic hepatitis.

Cancer-Associated Adipocytes in Breast Cancer: Causes and Consequences

Breast cancer progression is highly dependent on the heterotypic interaction between tumor cells and stromal cells of the tumor microenvironment. Cancer-associated adipocytes (CAAs) are emerging as breast cancer cell partners favoring proliferation, invasion, and metastasis. This article discussed the intersection between extracellular signals and the transcriptional cascade that regulates adipocyte differentiation in order to appreciate the molecular pathways that have been described to drive adipocyte dedifferentiation. Moreover, recent studies on the mechanisms through which CAAs affect the progression of breast cancer were reviewed, including adipokine regulation, metabolic reprogramming, extracellular matrix remodeling, and immune cell modulation. An in-depth understanding of the complex vicious cycle between CAAs and breast cancer cells is crucial for designing novel strategies for new therapeutic interventions.

Interplay between SMAD2 and STAT5A is a critical determinant of IL-17A/IL-17F differential expression

Interleukins (IL)-17A and F are critical cytokines in anti-microbial immunity but also contribute to auto-immune pathologies. Recent evidence suggests that they may be differentially produced by T-helper (Th) cells, but the underlying mechanisms remain unknown. To address this question, we built a regulatory graph integrating all reported upstream regulators of IL-17A and F, completed by ChIP-seq data analyses. The resulting regulatory graph encompasses 82 components and 136 regulatory links. The graph was then supplemented by logical rules calibrated with original flow cytometry data using naive CD4⁺ T cells, in conditions inducing IL-17A or IL-17F. The model displays specific stable states corresponding to virtual phenotypes explaining IL-17A and IL-17F differential regulation across eight cytokine stimulatory conditions. Our model analysis points to the transcription factors NFAT2A, STAT5A and SMAD2 as key regulators of the differential expression of IL-17A and IL-17F, with STAT5A controlling IL-17F expression, and an interplay of NFAT2A, STAT5A and SMAD2 controlling IL-17A expression. We experimentally observed that the production of IL-17A was correlated with an increase of SMAD2 transcription, and the expression of IL-17F correlated with an increase of BLIMP-1 transcription, together with an increase of STAT5A expression (mRNA), as predicted by our model. Interestingly, RORγt presumably plays a more determinant role in IL-17A expression as compared to IL-17F expression. In conclusion, we propose the first mechanistic model accounting for the differential expression of IL-17A and F in Th cells, providing a basis to design novel therapeutic interventions in auto-immune and inflammatory diseases.