A role of the latent TGF-beta 1-binding protein in the assembly and secretion of TGF-beta 1

Cell type-specific transforming growth factor-β (TGF-β) signaling in the regulation of salivary gland fibrosis and regeneration

Salivary gland damage and hypofunction result from various disorders, including autoimmune Sjögren's disease (SjD) and IgG4-related disease (IgG4-RD), as well as a side effect of radiotherapy for treating head and neck cancers. There are no therapeutic strategies to prevent the loss of salivary gland function in these disorders nor facilitate functional salivary gland regeneration. However, ongoing aquaporin-1 gene therapy trials to restore saliva flow show promise. To identify and develop novel therapeutic targets, we must better understand the cell-specific signaling processes involved in salivary gland regeneration. Transforming growth factor-β (TGF-β) signaling is essential to tissue fibrosis, a major endpoint in salivary gland degeneration, which develops in the salivary glands of patients with SjD, IgG4-RD, and radiation-induced damage. Though the deposition and remodeling of extracellular matrix proteins are essential to repair salivary gland damage, pathological fibrosis results in tissue hardening and chronic salivary gland dysfunction orchestrated by multiple cell types, including fibroblasts, myofibroblasts, endothelial cells, stromal cells, and lymphocytes, macrophages, and other immune cell populations. This review is focused on the role of TGF-β signaling in the development of salivary gland fibrosis and the potential for targeting TGF-β as a novel therapeutic approach to regenerate functional salivary glands. The studies presented highlight the divergent roles of TGF-β signaling in salivary gland development and dysfunction and illuminate specific cell populations in damaged or diseased salivary glands that mediate the effects of TGF-β. Overall, these studies strongly support the premise that blocking TGF-β signaling holds promise for the regeneration of functional salivary glands.

Molecular force-induced liberation of transforming growth factor-beta remodels the spleen for ectopic liver regeneration

BACKGROUND & AIMS

Ectopic liver regeneration in the spleen is a promising alternative to organ transplantation for treating liver failure. To accommodate transplanted liver cells, the splenic tissue must undergo structural changes to increase extracellular matrix content, demanding a safe and efficient approach for tissue remodelling.

METHODS

We synthesised sulphated hyaluronic acid (sHA) with an affinity for the latent complex of transforming growth factor-β (TGF-β) and cross-linked it into a gel network (sHA-X) via click chemistry. We injected this glycan into the spleens of mice to induce splenic tissue remodelling via supraphysiological activation of endogenous TGF-β.

RESULTS

sHA-X efficiently bound to the abundant latent TGF-β in the spleen. It provided the molecular force to liberate the active TGF-β dimers from their latent complex, mimicking the 'bind-and-pull' mechanism required for physiological activation of TGF-β and reshaping the splenic tissue to support liver cell growth. Hepatocytes transplanted into the remodelled spleen developed into liver tissue with sufficient volume to rescue animals with a metabolic liver disorder (Fah-/- transgenic model) or following 90% hepatectomy, with no adverse effects observed and no additional drugs required.

CONCLUSION

Our findings highlight the efficacy and translational potential of using sHA-X to remodel a specific organ by mechanically activating one single cytokine, representing a novel strategy for the design of biomaterials-based therapies for organ regeneration.

IMPACT AND IMPLICATIONS

Cell transplantation may provide a lifeline to millions of patients with end-stage liver diseases, but their severely damaged livers being unable to accommodate the transplanted cells is a crucial hurdle. Herein, we report an approach to restore liver functions in another organ - the spleen - by activating one single growth factor in situ. This approach, based on a chemically designed polysaccharide that can mechanically liberate the active transforming growth factor-β to an unusually high level, promotes the function of abundant allogenic liver cells in the spleen, rescuing animals from lethal models of liver diseases and showing a high potential for clinical translation.

Functional diversity of apoptotic vesicle subpopulations from bone marrow mesenchymal stem cells in tissue regeneration

Apoptosis releases numerous apoptotic vesicles that regulate processes such as cell proliferation, immunity, and tissue regeneration and repair. Now, it has also emerged as an attractive candidate for biotherapeutics. However, apoptotic vesicles encompass a diverse range of subtypes, and it remains unclear which specific subtypes play a pivotal role. In this study, we successfully isolated different apoptotic vesicle subtypes based on their sizes and characterized them using NTA and TEM techniques, respectively. We compared the functional variances among the distinct subtypes of apoptotic vesicles in terms of stem cell proliferation, migration, and differentiation, as well as for endothelial cell and macrophage function, effectively identifying subtypes that exhibit discernible functional differences. ApoSEV (with diameter <1000 nm) promoted stem cell proliferation, migration, and multi-potent differentiation, and accelerated skin wound healing of diabetes mouse model, while apoBD (with diameter >1000 nm) played the opposite effect on cell function and tissue regeneration. Lastly, employing protein analysis and gene sequencing techniques, we elucidated the intrinsic mechanisms underlying these differences between different subtypes of apoEVs. Collectively, this study identified that apoptotic vesicle subtypes possessed distinct bio-functions in regulating stem cell function and behaviour and modulating tissue regeneration, which primarily attribute to the distinct profiling of protein and mRNA in different subtypes. This comprehensive analysis of specific subtypes of apoEVs would provide novel insights for potential therapeutic applications in cell biology and tissue regeneration.

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

A prognostic marker LTBP1 is associated with epithelial mesenchymal transition and can promote the progression of gastric cancer

LTBP1 is closely related to TGF-β1 function as an essential component, which was unclear in gastric cancer (GC). Harbin Medical University (HMU)-GC cohort and The Cancer Genome Atlas (TCGA) dataset were combined to form a training cohort to calculate the connection between LTBP1 mRNA expression, prognosis and clinicopathological features. The training cohort was also used to verify the biological function of LTBP1 and its relationship with immune microenvironment and chemosensitivity. In the tissue microarrays (TMAs), immunohistochemical (IHC) staining was performed to observe LTBP1 protein expression. The correlation between LTBP1 protein expression level and prognosis was also analyzed, and a nomogram model was constructed. Western blotting (WB) was used in cell lines to assess LTBP1 expression. Transwell assays and CCK-8 were employed to assess LTBP1's biological roles. In compared to normal gastric tissues, LTBP1 expression was upregulated in GC tissues, and high expression was linked to a bad prognosis for GC patients. Based on a gene enrichment analysis, LTBP1 was primarily enriched in the TGF-β and EMT signaling pathways. Furthermore, high expression of LTBP1 in the tumor microenvironment was positively correlated with an immunosuppressive response. We also found that LTBP1 expression (p = 0.006) and metastatic lymph node ratio (p = 0.044) were independent prognostic risk factors for GC patients. The prognostic model combining LTBP1 expression and lymph node metastasis ratio reliably predicted the prognosis of GC patients. In vitro proliferation and invasion of MKN-45 GC cells were inhibited and their viability was decreased by LTBP1 knockout. LTBP1 plays an essential role in the development and progression of GC, and is a potential prognostic biomarker and therapeutic target for GC.

Advanced biosensors for nanomaterial-based detection of transforming growth factor alpha and beta, a class of major polypeptide regulators

Transforming growth factors (TGFs) regulate several cellular processes including, differentiation, growth, migration, extracellular matrix production, and apoptosis. TGF alpha (TGF-α) is a heterogeneous molecule containing 160 amino acid residues. It is a potent angiogenesis promoter that is activated by JAK-STAT signaling. Whereas TGF beta (TGF-β) consists of 390-412 amino acids. Smad and non-Smad signaling both occur in TGF beta. It is linked to immune cell activation, differentiation, and proliferation. It also triggers pre-apoptotic responses and inhibits cell proliferation. Both growth factors have a promising role in the development and homeostasis of tissues. Defects such as autoimmune diseases and cancer develop mechanisms to modulate checkpoints of the immune system resulting in altered growth factors profile. An accurate amount of these growth factors is essential for normal functioning, but an exceed or fall behind the normal level is alarming as it is linked to several disorders. This demands techniques for TGF-α and TGF-β profiling to effectively diagnose diseases, monitor their progression, and assess the efficacy of immunotherapeutic drugs. Quantitative detection techniques including the emergence of biosensing technology seem to accomplish the purpose. Until the present time, few biosensors have been designed in the context of TGF-α and TGF-β for disease detection, analyzing receptor binding, and interaction with carriers. In this paper, we have reviewed the physiology of transforming growth factor alpha and beta, including the types, structure, function, latent/active forms, signaling, and defects caused. It involves the description of biosensors on TGF-α and TGF-β, advances in technology, and future perspectives.

Brachyolmia, dental anomalies and short stature (DASS): Phenotype and genotype analyses of Egyptian and Pakistani patients

Brachyolmia is a heterogeneous group of developmental disorders characterized by a short trunk, short stature, scoliosis, and generalized platyspondyly without significant deformities in the long bones. DASS (Dental Abnormalities and Short Stature), caused by alterations in the LTBP3 gene, was previously considered as a subtype of brachyolmia. The present study investigated three unrelated consanguineous families (A, B, C) with Brachyolmia and DASS from Egypt and Pakistan. In our Egyptian patients, we also observed hearing impairment. Exome sequencing was performed to determine the genetic causes of the diverse clinical conditions in the patients. Exome sequencing identified a novel homozygous splice acceptor site variant (LTBP3:c.3629-1G > T; p. ?) responsible for DASS phenotypes and a known homozygous missense variant (CABP2: c.590T > C; p.Ile197Thr) causing hearing impairment in the Egyptian patients. In addition, two previously reported homozygous frameshift variants (LTBP3:c.132delG; p.Pro45Argfs*25) and (LTBP3:c.2216delG; p.Gly739Alafs*7) were identified in Pakistani patients. This study emphasizes the vital role of LTBP3 in the axial skeleton and tooth morphogenesis and expands the mutational spectrum of LTBP3. We are reporting LTBP3 variants in seven patients of three families, majorly causing brachyolmia with dental and cardiac anomalies. Skeletal assessment documented short webbed neck, broad chest, evidences of mild long bones involvement, short distal phalanges, pes planus and osteopenic bone texture as additional associated findings expanding the clinical phenotype of DASS. The current study reveals that the hearing impairment phenotype in Egyptian patients of family A has a separate transmission mechanism independent of LTBP3.

Plasma LTBP2 as a potential biomarker in differential diagnosis of connective tissue disease-associated interstitial lung disease and idiopathic pulmonary fibrosis: a pilot study

Few biomarkers distinguish connective tissue disease-associated interstitial lung disease (CTD-ILD) from idiopathic pulmonary fibrosis (IPF). Latent transforming growth factor-β binding protein-2 (LTBP2), a secreted extracellular matrix protein, is involved in pulmonary fibrosis. However, the role of LTBP2 in differentially diagnosing CTD-ILD and IPF is unclear. In this study, enzyme-linked immunosorbent assays quantified plasma LTBP2 concentrations in 200 individuals (35 healthy controls, 42 CTD patients without ILD, 89 CTD-ILD patients, and 34 IPF patients). CTD-ILD and IPF were further classified based on chest imaging pattern and pulmonary function test results. Plasma LTBP2 levels were significantly elevated in the IPF group compared with the CTD-ILD group. ROC analysis further suggested the possible value of LTBP2 in differentially diagnosing CTD-ILD and IPF. Additionally, CTD-ILD patients with progressive lung fibrosis had higher plasma LTBP2 concentrations than those who did not. Similarly, patients with IPF developing acute exacerbation showed higher plasma LTBP2 levels than those with stable IPF. This is the first study showing that LTBP2 was closely associated with the usual interstitial pneumonia (UIP) pattern in rheumatoid arthritis-associated ILD (RA-ILD). Moreover, the optimal cutoff values of LTBP2 for distinguishing IPF from CTD-UIP/RA-UIP were 33.75 and 38.33 ng/mL with an AUC of 0.682 and 0.681, respectively. Our findings suggest that plasma LTBP2 levels may differentially diagnose CTD-ILD and IPF, and assess their fibrotic activity. Additionally, clinical LTBP2 evaluation may be a great aid to identifying the presence of the UIP pattern in RA-ILD and to discriminating IPF from CTD-UIP, particularly RA-UIP.

Molecular mechanisms controlling the biogenesis of the TGF-β signal Vg1

The TGF-beta signals Vg1 (Dvr1/Gdf3) and Nodal form heterodimers to induce vertebrate mesendoderm. The Vg1 proprotein is a monomer retained in the endoplasmic reticulum (ER) and is processed and secreted upon heterodimerization with Nodal, but the mechanisms underlying Vg1 biogenesis are largely elusive. Here, we clarify the mechanisms underlying Vg1 retention, processing, secretion, and signaling and introduce a Synthetic Processing (SynPro) system that enables the programmed cleavage of ER-resident and extracellular proteins. First, we find that Vg1 can be processed by intra- or extracellular proteases. Second, Vg1 can be processed without Nodal but requires Nodal for secretion and signaling. Third, Vg1-Nodal signaling activity requires Vg1 processing, whereas Nodal can remain unprocessed. Fourth, Vg1 employs exposed cysteines, glycosylated asparagines, and BiP chaperone-binding motifs for monomer retention in the ER. These observations suggest two mechanisms for rapid mesendoderm induction: Chaperone-binding motifs help store Vg1 as an inactive but ready-to-heterodimerize monomer in the ER, and the flexibility of Vg1 processing location allows efficient generation of active heterodimers both intra- and extracellularly. These results establish SynPro as an in vivo processing system and define molecular mechanisms and motifs that facilitate the generation of active TGF-beta heterodimers.

Dupuytren's Disease Is Mediated by Insufficient TGF-β1 Release and Degradation

Dupuytren's disease (DD) is a fibroproliferative disorder affecting the palmar fascia, causing functional restrictions of the hand and thereby limiting patients' daily lives. The disturbed and excessive myofibroblastogenesis, causing DD, is mainly induced by transforming growth factor (TGF)-β1. But, the extent to which impaired TGF-β1 release or TGF-β signal degradation is involved in pathologically altered myofibroblastogenesis in DD has been barely examined. Therefore, the complex in which TGF-β1 is secreted in the extracellular matrix to elicit its biological activity, and proteins such as plasmin, integrins, and matrix metalloproteinases (MMPs), which are involved in the TGF-β1 activation, were herein analyzed in DD-fibroblasts (DD-FBs). Additionally, TGF-β signal degradation via caveolin-1 was examined with 5-fluoruracil (5-FU) in detail. Gene expression analysis was performed via Western blot, PCR, and immunofluorescence analyses. As a surrogate parameter for disturbed myofibroblastogenesis, 𝛼-smooth-muscle-actin (𝛼-SMA) expression was evaluated. It was demonstrated that latency-associated peptide (LAP)-TGF-β and latent TGF-β-binding protein (LTBP)-1 involved in TGF-β-complex building were significantly upregulated in DD. Plasmin a serinprotease responsible for the TGF-β release was significantly downregulated. The application of exogenous plasmin was able to inhibit disturbed myofibroblastogenesis, as measured via 𝛼-SMA expression. Furthermore, a reduced TGF-β1 degradation was also involved in the pathological phenotype of DD, because caveolin-1 expression was significantly downregulated, and if rescued, myofibroblastogenesis was also inhibited. Therefore, our study demonstrates that a deficient release and degradation of TGF-β1 are important players in the pathological phenotype of DD and should be addressed in future research studies to improve DD therapy or other related fibrotic conditions.

Intricacies of TGF-β signaling in Treg and Th17 cell biology

Balanced immunity is pivotal for health and homeostasis. CD4+ helper T (Th) cells are central to the balance between immune tolerance and immune rejection. Th cells adopt distinct functions to maintain tolerance and clear pathogens. Dysregulation of Th cell function often leads to maladies, including autoimmunity, inflammatory disease, cancer, and infection. Regulatory T (Treg) and Th17 cells are critical Th cell types involved in immune tolerance, homeostasis, pathogenicity, and pathogen clearance. It is therefore critical to understand how Treg and Th17 cells are regulated in health and disease. Cytokines are instrumental in directing Treg and Th17 cell function. The evolutionarily conserved TGF-β (transforming growth factor-β) cytokine superfamily is of particular interest because it is central to the biology of both Treg cells that are predominantly immunosuppressive and Th17 cells that can be proinflammatory, pathogenic, and immune regulatory. How TGF-β superfamily members and their intricate signaling pathways regulate Treg and Th17 cell function is a question that has been intensely investigated for two decades. Here, we introduce the fundamental biology of TGF-β superfamily signaling, Treg cells, and Th17 cells and discuss in detail how the TGF-β superfamily contributes to Treg and Th17 cell biology through complex yet ordered and cooperative signaling networks.

MT1-MMP as a Key Regulator of Metastasis

Membrane type1-matrix metalloproteinase (MT1-MMP) is a member of metalloproteinases that is tethered to the transmembrane. Its major function in cancer progression is to directly degrade the extracellular matrix components, which are mainly type I-III collagen or indirectly type IV collagen through the activation of MMP-2 with a cooperative function of the tissue inhibitor of metalloproteinase-2 (TIMP-2). MT1-MMP is expressed as an inactive form (zymogen) within the endoplasmic reticulum (ER) and receives truncation processing via furin for its activation. Upon the appropriate trafficking of MT1-MMP from the ER, the Golgi apparatus to the cell surface membrane, MT1-MMP exhibits proteolytic activities to the surrounding molecules such as extracellular matrix components and cell surface molecules. MT1-MMP also retains a non-proteolytic ability to activate hypoxia-inducible factor 1 alpha (HIF-1A) via factors inhibiting the HIF-1 (FIH-1)-Mint3-HIF-1 axis, resulting in the upregulation of glucose metabolism and oxygen-independent ATP production. Through various functions of MT1-MMP, cancer cells gain motility on migration/invasion, thus causing metastasis. Despite the long-time efforts spent on the development of MT1-MMP interventions, none have been accomplished yet due to the side effects caused by off-target effects. Recently, MT1-MMP-specific small molecule inhibitors or an antibody have been reported and these inhibitors could potentially be novel agents for cancer treatment.

Inhibition of the extracellular enzyme A disintegrin and metalloprotease with thrombospondin motif 4 prevents cardiac fibrosis and dysfunction

AIMS

Heart failure is a condition with high mortality rates, and there is a lack of therapies that directly target maladaptive changes in the extracellular matrix (ECM), such as fibrosis. We investigated whether the ECM enzyme known as A disintegrin and metalloprotease with thrombospondin motif (ADAMTS) 4 might serve as a therapeutic target in treatment of heart failure and cardiac fibrosis.

METHODS AND RESULTS

The effects of pharmacological ADAMTS4 inhibition on cardiac function and fibrosis were examined in rats exposed to cardiac pressure overload. Disease mechanisms affected by the treatment were identified based on changes in the myocardial transcriptome. Following aortic banding, rats receiving an ADAMTS inhibitor, with high inhibitory capacity for ADAMTS4, showed substantially better cardiac function than vehicle-treated rats, including ∼30% reduction in E/e' and left atrial diameter, indicating an improvement in diastolic function. ADAMTS inhibition also resulted in a marked reduction in myocardial collagen content and a down-regulation of transforming growth factor (TGF)-β target genes. The mechanism for the beneficial effects of ADAMTS inhibition was further studied in cultured human cardiac fibroblasts producing mature ECM. ADAMTS4 caused a 50% increase in the TGF-β levels in the medium. Simultaneously, ADAMTS4 elicited a not previously known cleavage of TGF-β-binding proteins, i.e. latent-binding protein of TGF-β and extra domain A-fibronectin. These effects were abolished by the ADAMTS inhibitor. In failing human hearts, we observed a marked increase in ADAMTS4 expression and cleavage activity.

CONCLUSION

Inhibition of ADAMTS4 improves cardiac function and reduces collagen accumulation in rats with cardiac pressure overload, possibly through a not previously known cleavage of molecules that control TGF-β availability. Targeting ADAMTS4 may serve as a novel strategy in heart failure treatment, in particular, in heart failure with fibrosis and diastolic dysfunction.

MDM2 Influences ACE2 Stability and SARS-CoV-2 Uptake

Angiotensin-converting enzyme 2 (ACE2) is the central entry receptor for SARS-CoV-2. However, surprisingly little is known about the effects of host regulators on ACE2 localization, expression, and the associated influence on SARS-CoV-2 infection. Here we identify that ACE2 expression levels are regulated by the E3 ligase MDM2 and that MDM2 levels indirectly influence infection with SARS-CoV-2. Genetic depletion of MDM2 elevated ACE2 expression levels, which strongly promoted infection with all SARS-CoV-2 isolates tested. SARS-CoV-2 spike-pseudotyped viruses and the uptake of non-replication-competent virus-like particles showed that MDM2 affects the viral uptake process. MDM2 ubiquitinates Lysine 788 of ACE2 to induce proteasomal degradation, and degradation of this residue led to higher ACE2 expression levels and superior virus particle uptake. Our study illustrates that cellular regulators of ACE2 stability, such as MDM2, play an important role in defining the infection capabilities of SARS-CoV-2.

A specialized integrin-binding motif enables proTGF-β2 activation by integrin αVβ6 but not αVβ8

Activation of latent transforming growth factor (TGF)-β2 is incompletely understood. Unlike TGF-β1 and β3, the TGF-β2 prodomain lacks a seven-residue RGDLXX (L/I) integrin-recognition motif and is thought not to be activated by integrins. Here, we report the surprising finding that TGF-β2 contains a related but divergent 13-residue integrin-recognition motif (YTSGDQKTIKSTR) that specializes it for activation by integrin αVβ6 but not αVβ8. Both classes of motifs compete for the same binding site in αVβ6. Multiple changes in the longer motif underlie its specificity. ProTGF-β2 structures define interesting differences from proTGF-β1 and the structural context for activation by αVβ6. Some integrin-independent activation is also seen for proTGF-β2 and even more so for proTGF-β3. Our findings have important implications for therapeutics to αVβ6 in clinical trials for fibrosis, in which inhibition of TGF-β2 activation has not been anticipated.

TGFβ signaling pathways in human health and disease

Transforming growth factor beta (TGFβ) is named for the function it was originally discovered to perform-transformation of normal cells into aggressively growing malignant cells. It became apparent after more than 30 years of research, however, that TGFβ is a multifaceted molecule with a myriad of different activities. TGFβs are widely expressed with almost every cell in the human body producing one or another TGFβ family member and expressing its receptors. Importantly, specific effects of this growth factor family differ in different cell types and under different physiologic and pathologic conditions. One of the more important and critical TGFβ activities is the regulation of cell fate, especially in the vasculature, that will be the focus of this review.

Fibrillin microfibril structure identifies long-range effects of inherited pathogenic mutations affecting a key regulatory latent TGFβ-binding site

Genetic mutations in fibrillin microfibrils cause serious inherited diseases, such as Marfan syndrome and Weill-Marchesani syndrome (WMS). These diseases typically show major dysregulation of tissue development and growth, particularly in skeletal long bones, but links between the mutations and the diseases are unknown. Here we describe a detailed structural analysis of native fibrillin microfibrils from mammalian tissue by cryogenic electron microscopy. The major bead region showed pseudo eightfold symmetry where the amino and carboxy termini reside. On the basis of this structure, we show that a WMS deletion mutation leads to the induction of a structural rearrangement that blocks interaction with latent TGFβ-binding protein-1 at a remote site. Separate deletion of this binding site resulted in the assembly of shorter fibrillin microfibrils with structural alterations. The integrin α_vβ₃-binding site was also mapped onto the microfibril structure. These results establish that in complex extracellular assemblies, such as fibrillin microfibrils, mutations may have long-range structural consequences leading to the disruption of growth factor signaling and the development of disease.

The Role of TGF-β3 in Radiation Response

Transforming growth factor-beta 3 (TGF-β3) is a ubiquitously expressed multifunctional cytokine involved in a range of physiological and pathological conditions, including embryogenesis, cell cycle regulation, immunoregulation, and fibrogenesis. The cytotoxic effects of ionizing radiation are employed in cancer radiotherapy, but its actions also influence cellular signaling pathways, including that of TGF-β3. Furthermore, the cell cycle regulating and anti-fibrotic effects of TGF-β3 have identified it as a potential mitigator of radiation- and chemotherapy-induced toxicity in healthy tissue. This review discusses the radiobiology of TGF-β3, its induction in tissue by ionizing radiation, and its potential radioprotective and anti-fibrotic effects.

Angiotensin II Increases Oxidative Stress and Inflammation in Female, But Not Male, Endothelial Cells

Introduction

Women are at elevated risk for certain cardiovascular diseases, including pulmonary arterial hypertension, Alzheimer's disease, and vascular complications of diabetes. Angiotensin II (AngII), a circulating stress hormone, is elevated in cardiovascular disease; however, our knowledge of sex differences in the vascular effects of AngII are limited. We therefore analyzed sex differences in human endothelial cell response to AngII treatment.

Methods

Male and female endothelial cells were treated with AngII for 24 h and analyzed by RNA sequencing. We then used endothelial and mesenchymal markers, inflammation assays, and oxidative stress indicators to measure female and male endothelial cell functional changes in response to AngII.

Results

Our data show that female and male endothelial cells are transcriptomically distinct. Female endothelial cells treated with AngII had widespread gene expression changes related to inflammatory and oxidative stress pathways, while male endothelial cells had few gene expression changes. While both female and male endothelial cells maintained their endothelial phenotype with AngII treatment, female endothelial cells showed increased release of the inflammatory cytokine interleukin-6 and increased white blood cell adhesion following AngII treatment concurrent with a second inflammatory cytokine. Additionally, female endothelial cells had elevated reactive oxygen species production compared to male endothelial cells after AngII treatment, which may be partially due to nicotinamide adenine dinucleotide phosphate oxidase-2 (NOX2) escape from X-chromosome inactivation.

Conclusions

These data suggest that endothelial cells have sexually dimorphic responses to AngII, which could contribute to increased prevalence of some cardiovascular diseases in women.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-023-00762-2.

Pitx2 patterns an accelerator-brake mechanical feedback through latent TGFβ to rotate the gut

The vertebrate intestine forms by asymmetric gut rotation and elongation, and errors cause lethal obstructions in human infants. Rotation begins with tissue deformation of the dorsal mesentery, which is dependent on left-sided expression of the Paired-like transcription factor Pitx2. The conserved morphogen Nodal induces asymmetric Pitx2 to govern embryonic laterality, but organ-level regulation of Pitx2 during gut asymmetry remains unknown. We found Nodal to be dispensable for Pitx2 expression during mesentery deformation. Intestinal rotation instead required a mechanosensitive latent transforming growth factor-β (TGFβ), tuning a second wave of Pitx2 that induced reciprocal tissue stiffness in the left mesentery as mechanical feedback with the right side. This signaling regulator, an accelerator (right) and brake (left), combines biochemical and biomechanical inputs to break gut morphological symmetry and direct intestinal rotation.

The Role of the Fibronectin Synergy Site for Skin Wound Healing

Skin is constantly exposed to injuries that are repaired with different outcomes, either regeneration or scarring. Scars result from fibrotic processes modulated by cellular physical forces transmitted by integrins. Fibronectin (FN) is a major component in the provisional matrix assembled to repair skin wounds. FN enables cell adhesion binding of α5β1/αIIbβ3 and αv-class integrins to an RGD-motif. An additional linkage for α5/αIIb is the synergy site located in close proximity to the RGD motif. The mutation to impair the FN synergy region (Fn1^syn/syn) demonstrated that its absence permits complete development. However, only with the additional engagement to the FN synergy site do cells efficiently resist physical forces. To test how the synergy site-mediated adhesion affects the course of wound healing fibrosis, we used a mouse model of skin injury and in-vitro migration studies with keratinocytes and fibroblasts on FN^syn. The loss of FN synergy site led to normal re-epithelialization caused by two opposing migratory defects of activated keratinocytes and, in the dermis, induced reduced fibrotic responses, with lower contents of myofibroblasts and FN deposition and diminished TGF-β1-mediated cell signalling. We demonstrate that weakened α5β1-mediated traction forces on FN^syn cause reduced TGF-β1 release from its latent complex.

Production of Recombinant Active Human TGFβ1 in Nicotiana benthamiana

The production of recombinant proteins in plant systems is receiving wider attention. Indeed, various plant-produced pharmaceuticals have been shown to be biologically active. However, the production of human growth factors and cytokines in heterologous systems is still challenging because they often act as complex forms, such as homo- or hetero-dimers, and their production is tightly regulated in vivo. In this study, we demonstrated that the mature form of human TGFβ1 produced and purified from Nicotiana benthamiana shows biological activity in animal cells. To produce the mature form of TGFβ1, various recombinant genes containing the mature form of TGFβ1 were generated and produced in N. benthamiana. Of these, a recombinant construct, BiP:M:CBM3:LAP[C33S]:EK:TGFβ1, was expressed at a high level in N. benthamiana. Recombinant proteins were one-step purified using cellulose-binding module 3 (CBM3) as an affinity tag and microcrystalline cellulose (MCC) beads as a matrix. The TGFβ1 recombinant protein bound on MCC beads was proteolytically processed with enterokinase to separate mature TGFβ1. The mature TGFβ1 still associated with Latency Associated Protein, [LAP(C33S)] that had been immobilized on MCC beads was released by HCl treatment. Purified TGFβ1 activated TGFβ1-mediated signaling in the A549 cell line, thereby inducing phosphorylation of SMAD-2, the expression of ZEB-2 and SNAIL1, and the formation of a filopodia-like structure. Based on these results, we propose that active mature TGFβ1, one of the most challenging growth factors to produce in heterologous systems, can be produced from plants at a high degree of purity via a few steps.

The prognostic significance of LTBP2 for malignant tumors: Evidence based on 11 observational studies

BACKGROUND AIMS

At present, increasing reports have shown that latent transforming growth factor-β-binding protein 2 (LTBP2) was associated with the prognosis of many types of cancer. We performed rounded analysis to comprehensively analyze and evaluate the prognostic significance of LTBP2 for patients with malignant tumors.

METHODS

We identified relevant studies by searching database including PubMed, Embase, Cochrane Library, and Web of Science. The odds ratio with its 95% confidence interval (CI) was used to assess the correlation between LTBP2 and clinicopathologic features or overall survival of patients with cancer. Hazard ratio with its 95% CI was used to explore the prognostic risk factors. The analysis was performed and assessed using Review Manager 5.2.

RESULTS

A total of 11 studies including 2322 participants were included in this systematic review. Pooled results showed that malignant tissues experienced higher incidence of high LTBP2 expression when compared with adjacent or normal tissues. Patients with high LTBP2 expression experienced significantly lower 1-year, 2-year, 3-year, and 4-year overall survival rate, with the pooled odds ratios being 0.26 (95% CI 0.13-0.53; P = .0002), 0.27 (95% CI 0.14-0.50; P < .0001), 0.26 (95% CI 0.13-0.53; P = .0002), and 0.21 (95% CI 0.06-0.73; P = .01) respectively. Univariate analysis showed high LTBP2 expression, tumor node metastasis stage, T stage, and N stage were prognostic factors of patients with tumors. Multivariate analysis indicated high LTBP2 expression was an independent prognostic factor.

CONCLUSIONS

The present analysis suggested that LTBP2 may have significant association with survival of patients with cancer. High LTBP2 expression was an independent prognostic factor and indicated poor survival.

Identification, function, and biological relevance of POGLUT2 and POGLUT3

O-glycosylation of Epidermal Growth Factor-like (EGF) repeats plays crucial roles in protein folding, trafficking and function. The Notch extracellular domain has been used as a model to study these mechanisms due to its many O-glycosylated EGF repeats. Three enzymes were previously known to O-glycosylate Notch EGF repeats: Protein O-Glucosyltransferase 1 (POGLUT1), Protein O-Fucosyltransferase 1 (POFUT1), and EGF Domain Specific O-Linked N-Acetylglucosamine Transferase (EOGT). All of these modifications affect Notch activity. Recently, POGLUT2 and POGLUT3 were identified as two novel O-glucosyltransferases that modify a few Notch EGF repeats at sites distinct from those modified by POGLUT1. Comparison of these modification sites revealed a putative consensus sequence which predicted modification of many extracellular matrix proteins including fibrillins (FBNs) and Latent TGFβ-binding proteins (LTBPs). Glycoproteomic analysis revealed that approximately half of the 47 EGF repeats in FBN1 and FBN2, and half of the 18 EGF repeats in LTBP1, are modified by POGLUT2 and/or POGLUT3. Cellular assays showed that loss of modifications by POGLUT2 and/or POGLUT3 significantly reduces FBN1 secretion. There is precedent for EGF modifications to affect protein-protein interactions, as has been demonstrated by research of POGLUT1 and POFUT1 modifications on Notch. Here we discuss the identification and characterization of POGLUT2 and POGLUT3 and the ongoing research that continues to elucidate the biological significance of these novel enzymes.

Elastic Fibre Proteins in Elastogenesis and Wound Healing

As essential components of our connective tissues, elastic fibres give tissues such as major blood vessels, skin and the lungs their elasticity. Their formation is complex and co-ordinately regulated by multiple factors. In this review, we describe key players in elastogenesis: fibrillin-1, tropoelastin, latent TGFβ binding protein-4, and fibulin-4 and -5. We summarise their roles in elastogenesis, discuss the effect of their mutations on relevant diseases, and describe their interactions involved in forming the elastic fibre network. Moreover, we look into their roles in wound repair for a better understanding of their potential application in tissue regeneration.

Diversity of Dysregulated Long Non-Coding RNAs in HBV-Related Hepatocellular Carcinoma

Infection with the hepatitis B virus (HBV) continues to pose a major threat to public health as approximately 292 million people worldwide are currently living with the chronic form of the disease, for which treatment is non-curative. Chronic HBV infections often progress to hepatocellular carcinoma (HCC) which is one of the world’s leading causes of cancer-related deaths. Although the process of hepatocarcinogenesis is multifaceted and has yet to be fully elucidated, several studies have implicated numerous long non-coding RNAs (lncRNAs) as contributors to the development of HCC. These host-derived lncRNAs, which are often dysregulated as a consequence of viral infection, have been shown to function as signals, decoys, guides, or scaffolds, to modulate gene expression at epigenetic, transcriptional, post-transcriptional and even post-translational levels. These lncRNAs mainly function to promote HBV replication and oncogene expression or downregulate tumor suppressors. Very few lncRNAs are known to suppress tumorigenesis and these are often downregulated in HCC. In this review, we describe the mechanisms by which lncRNA dysregulation in HBV-related HCC promotes tumorigenesis and cancer progression.

Fibulin-4 accelerates amyloid formation through binding with a keratin 5 peptide fragment

Keratins are the major amyloid fibril component in localized cutaneous amyloidosis. We analyzed the amyloid components in the skin of patients with localized cutaneous amyloidosis by immunohistochemical staining using antisera against extracellular matrix proteins and keratin 5 (K5). Fibulin-4 and K5 colocalized in the amyloid deposits. Using 14 synthetic peptides, we screened for amyloidogenic sequences in the C-terminal region of K5, including the α-helical rod domain and the tail domain. Two peptides stained with thioflavin T possessed a β-sheet structure and formed amyloid-like fibrils. Among the amyloidogenic peptides, a peptide KT5-6 (YQELMNTKLALDVEIATYRKLLEGE) derived from the α-helical rod domain of K5 specifically bound to fibulin-4. In addition, amyloid formation of KT5-6 was accelerated by fibulin-4. These results suggest that degraded fragments of K5 containing the KT5-6 sequence form amyloid fibrils with fibulin-4. The data further suggest that degraded fragments of K5 and fibulin-4 have the potential to initiate cutaneous amyloidosis.

Transforming growth factor β latency: A mechanism of cytokine storage and signalling regulation in liver homeostasis and disease

Transforming growth factor-β (TGF-β) is a potent effector in the liver, which is involved in a plethora of processes initiated upon liver injury. TGF-β affects parenchymal, non-parenchymal, and inflammatory cells in a highly context-dependent manner. Its bioavailability is critical for a fast response to various insults. In the liver – and probably in other organs – this is made possible by the deposition of a large portion of TGF-β in the extracellular matrix as an inactivated precursor form termed latent TGF-β (L-TGF-β). Several matrisomal proteins participate in matrix deposition, latent complex stabilisation, and activation of L-TGF-β. Extracellular matrix protein 1 (ECM1) was recently identified as a critical factor in maintaining the latency of deposited L-TGF-β in the healthy liver. Indeed, its depletion causes spontaneous TGF-β signalling activation with deleterious effects on liver architecture and function. This review article presents the current knowledge on intracellular L-TGF-β complex formation, secretion, matrix deposition, and activation and describes the proteins and processes involved. Further, we emphasise the therapeutic potential of toning down L-TGF-β activation in liver fibrosis and liver cancer.

Latent Transforming Growth Factor-β Binding Protein-2 Regulates Lung Fibroblast-to-Myofibroblast Differentiation in Pulmonary Fibrosis via NF-κB Signaling

Despite past extensive studies, the mechanisms underlying pulmonary fibrosis (PF) still remain poorly understood. The aberrantly activated lung myofibroblasts, predominantly emerging through fibroblast-to-myofibroblast differentiation, are considered to be the key cells in PF, resulting in excessive accumulation of extracellular matrix (ECM). Latent transforming growth factor-β (TGFβ) binding protein-2 (LTBP2) has been suggested as playing a critical role in modulating the structural integrity of the ECM. However, its function in PF remains unclear. Here, we demonstrated that lungs originating from different types of patients with PF, including idiopathic PF and rheumatoid arthritis-associated interstitial lung disease, and from mice following bleomycin (BLM)-induced PF were characterized by increased LTBP2 expression in activated lung fibroblasts/myofibroblasts. Moreover, serum LTBP2 was also elevated in patients with COVID-19-related PF. LTBP2 silencing by lentiviral shRNA transfection protected against BLM-induced PF and suppressed fibroblast-to-myofibroblast differentiation in vivo and in vitro. More importantly, LTBP2 overexpression was able to induce differentiation of lung fibroblasts to myofibroblasts in vitro, even in the absence of TGFβ1. By further mechanistic analysis, we demonstrated that LTBP2 silencing prevented fibroblast-to-myofibroblast differentiation and subsequent PF by suppressing the phosphorylation and nuclear translocation of NF-κB signaling. LTBP2 overexpression-induced fibroblast-to-myofibroblast differentiation depended on the activation of NF-κB signaling in vitro. Therefore, our data indicate that intervention to silence LTBP2 may represent a promising therapy for PF.

Early fish domestication affects methylation of key genes involved in the rapid onset of the farmed phenotype

Animal domestication is a process of environmental modulation and artificial selection leading to permanent phenotypic modifications. Recent studies showed that phenotypic changes occur very early in domestication, i.e., within the first generation in captivity, which raises the hypothesis that epigenetic mechanisms may play a critical role on the early onset of the domestic phenotype. In this context, we applied reduced representation bisulphite sequencing to compare methylation profiles between wild Nile tilapia females and their offspring reared under farmed conditions. Approximately 700 differentially methylated CpG sites were found, many of them associated not only with genes involved in muscle growth, immunity, autophagy and diet response but also related to epigenetic mechanisms, such as RNA methylation and histone modifications. This bottom-up approach showed that the phenotypic traits often related to domestic animals (e.g., higher growth rate and different immune status) may be regulated epigenetically and prior to artificial selection on gene sequences. Moreover, it revealed the importance of diet in this process, as reflected by differential methylation patterns in genes critical to fat metabolism. Finally, our study highlighted that the TGF-β1 signalling pathway may regulate and be regulated by several differentially methylated CpG-associated genes. This could be an important and multifunctional component in promoting adaptation of fish to a domestic environment while modulating growth and immunity-related traits.

The role of LTBPs in TGF beta signaling

The purpose of this review is to discuss the transforming growth factor beta (TGFB) binding proteins (LTBP) with respect to their participation in the activity of TGFB. We first describe pertinent aspects of the biology and cell function of the LTBPs. We then summarize the physiological consequences of LTBP loss in humans and mice. Finally, we consider a number of outstanding questions relating to LTBP function.

Novel LTBP3 mutations associated with thoracic aortic aneurysms and dissections

BACKGROUND

Thoracic aortic aneurysm and dissection (TAAD) is a hidden-onset but life-threatening disorder with high clinical variability and genetic heterogeneity. In recent years, an increasing number of genes have been identified to be related to TAAD. However, some genes remain uncertain because of limited case reports and/or functional studies. LTBP3 was such an ambiguous gene that was previously known for dental and skeletal dysplasia and then noted to be associated with TAAD. More research on individuals or families harboring variants in this gene would be helpful to obtain full knowledge of the disease and clarify its association with TAAD.

METHODS

A total of 266 TAAD probands with no causative mutations in known genes had been performed wholeexome sequencing (WES) to identify potentially pathogenic variants. In this study, rare LTBP3 variants were the focus of analysis.

RESULTS

Two compound heterozygous mutations, c.625dup (p.Leu209fs) and c.1965del (p.Arg656fs), in LTBP3 were identified in a TAAD patient along with short stature and dental problems, which was the first TAAD case with biallelic LTBP3 null mutations in an Asian population. Additionally, several rare heterozygous LTBP3 variants were also detected in other sporadic TAAD patients.

CONCLUSION

The identification of LTBP3 mutations in TAAD patients in our study provided more clinical evidence to support its association with TAAD, which broadens the gene spectrum of LTBP3. LTBP3 should be considered to be incorporated into the routine genetic analysis of heritable aortopathy, which might help to fully understand its phenotypic spectrum and improve the diagnostic rate of TAAD.

A Rare Case of Brachyolmia with Amelogenesis Imperfecta Caused by a New Pathogenic Splicing Variant in LTBP3

In recent years, a rare form of autosomal recessive brachyolmia associated with amelogenesis imperfecta (AI) has been described as a novel nosologic entity. This disorder is characterized by skeletal dysplasia (e.g., platyspondyly, short trunk, scoliosis, broad ilia, elongated femoral necks with coxa valga) and severe enamel and dental anomalies. Pathogenic variants in the latent transforming growth factor-β binding protein 3 (LTBP3) gene have been found implicated in the pathogenesis of this disorder. So far, biallelic pathogenic LTBP3 variants have been identified in less than 10 families. We here report a young boy born from consanguineous parents with a complex phenotype including skeletal dysplasia associated with aortic stenosis, hypertrophic cardiomyopathy, hypodontia and amelogenesis imperfecta caused by a previously unreported homozygous LTBP3 splice site variant. We also compare the genotypes and phenotypes of patients reported to date. This work provides further evidence that brachyolmia with amelogenesis imperfecta is a distinct nosologic entity and that variations in LTBP3 are involved in its pathogenesis.

Mechanical stretch sustains myofibroblast phenotype and function in microtissues through latent TGF-β1 activation

Developing methods to study tissue mechanics and myofibroblast activation may lead to new targets for therapeutic treatments that are urgently needed for fibrotic disease. Microtissue arrays are a promising approach to conduct relatively high-throughput research into fibrosis as they recapitulate key biomechanical aspects of the disease through a relevant 3D extracellular environment. In early work, our group developed a device called the MVAS-force to stretch microtissues while enabling simultaneous assessment of their dynamic mechanical behavior. Here, we investigated TGF-β1-induced fibroblast to myofibroblast differentiation in microtissue cultures using our MVAS-force device through assessing α-SMA expression, contractility and stiffness. In doing so, we linked cell-level phenotypic changes to functional changes that characterize the clinical manifestation of fibrotic disease. As expected, TGF-β1 treatment promoted a myofibroblastic phenotype and microtissues became stiffer and possessed increased contractility. These changes were partially reversible upon TGF-β1 withdrawal under a static condition, while, in contrast, long-term cyclic stretching maintained myofibroblast activation. This pro-fibrotic effect of mechanical stretching was absent when TGF-β1 receptors were inhibited. Furthermore, stretching promoted myofibroblast differentiation when microtissues were given latent TGF-β1. Altogether, these results suggest that external mechanical stretch may activate latent TGF-β1 and, accordingly, might be a powerful stimulus for continued myofibroblast activation to progress fibrosis. Further exploration of this pathway with our approach may yield new insights into myofibroblast activation and more effective therapeutic treatments for fibrosis.

POGLUT2 and POGLUT3 O-glucosylate multiple EGF repeats in fibrillin-1, -2, and LTBP1 and promote secretion of fibrillin-1

Fibrillin-1 (FBN1) is the major component of extracellular matrix microfibrils, which are required for proper development of elastic tissues, including the heart and lungs. Through protein-protein interactions with latent transforming growth factor (TGF) β-binding protein 1 (LTBP1), microfibrils regulate TGF-β signaling. Mutations within the 47 epidermal growth factor-like (EGF) repeats of FBN1 cause autosomal dominant disorders including Marfan Syndrome, which is characterized by disrupted TGF-β signaling. We recently identified two novel protein O-glucosyltransferases, Protein O-glucosyltransferase 2 (POGLUT2) and 3 (POGLUT3), that modify a small fraction of EGF repeats on Notch. Here, using mass spectral analysis, we show that POGLUT2 and POGLUT3 also modify over half of the EGF repeats on FBN1, fibrillin-2 (FBN2), and LTBP1. While most sites are modified by both enzymes, some sites show a preference for either POGLUT2 or POGLUT3. POGLUT2 and POGLUT3 are homologs of POGLUT1, which stabilizes Notch proteins by addition of O-glucose to Notch EGF repeats. Like POGLUT1, POGLUT2 and 3 can discern a folded versus unfolded EGF repeat, suggesting POGLUT2 and 3 are involved in a protein folding pathway. In vitro secretion assays using the N-terminal portion of recombinant FBN1 revealed reduced FBN1 secretion in POGLUT2 knockout, POGLUT3 knockout, and POGLUT2 and 3 double-knockout HEK293T cells compared with wild type. These results illustrate that POGLUT2 and 3 function together to O-glucosylate protein substrates and that these modifications play a role in the secretion of substrate proteins. It will be interesting to see how disease variants in these proteins affect their O-glucosylation.

TGF-β signaling: A recap of SMAD-independent and SMAD-dependent pathways

Transforming growth factor-β (TGF-β) is a proinflammatory cytokine known to control a diverse array of pathological and physiological conditions during normal development and tumorigenesis. TGF-β-mediated physiological effects are heterogeneous and vary among different types of cells and environmental conditions. TGF-β serves as an antiproliferative agent and inhibits tumor development during primary stages of tumor progression; however, during the later stages, it encourages tumor development and mediates metastatic progression and chemoresistance. The fundamental elements of TGF-β signaling have been divulged more than a decade ago; however, the process by which the signals are relayed from cell surface to nucleus is very complex with additional layers added in tumor cell niches. Although the intricate understanding of TGF-β-mediated signaling pathways and their regulation are still evolving, we tried to make an attempt to summarize the TGF-β-mediated SMAD-dependent andSMAD-independent pathways. This manuscript emphasizes the functions of TGF-β as a metastatic promoter and tumor suppressor during the later and initial phases of tumor progression respectively.

Multipotent adult progenitor cells induce regulatory T cells and promote their suppressive phenotype via TGFβ and monocyte-dependent mechanisms

Dysregulation of the immune system can initiate chronic inflammatory responses that exacerbate disease pathology. Multipotent adult progenitor cells (MAPC cells), an adult adherent bone-marrow derived stromal cell, have been observed to promote the resolution of uncontrolled inflammatory responses in a variety of clinical conditions including acute ischemic stroke, acute myocardial infarction (AMI), graft vs host disease (GvHD), and acute respiratory distress syndrome (ARDS). One of the proposed mechanisms by which MAPC cells modulate immune responses is via the induction of regulatory T cells (Tregs), however, the mechanism(s) involved remains to be fully elucidated. Herein, we demonstrate that, in an in vitro setting, MAPC cells increase Treg frequencies by promoting Treg proliferation and CD4⁺ T cell differentiation into Tregs. Moreover, MAPC cell-induced Tregs (miTregs) have a more suppressive phenotype characterized by increased expression of CTLA-4, HLA-DR, and PD-L1 and T cell suppression capacity. MAPC cells also promoted Treg activation by inducing CD45RA⁺ CD45RO⁺ transitional Tregs. Additionally, we identify transforming growth factor beta (TGFβ) as an essential factor for Treg induction secreted by MAPC cells. Furthermore, inhibition of indoleamine 2, 3-dioxygenase (IDO) resulted in decreased Treg induction by MAPC cells demonstrating IDO involvement. Our studies also show that CD14⁺ monocytes play a critical role in Treg induction by MAPC cells. Our study describes MAPC cell dependent Treg phenotypic changes and provides evidence of potential mechanisms by which MAPC cells promote Treg differentiation.

Connecting COPD GWAS genes: FAM13A controls TGFβ2 secretion by modulating AP-3 transport

Chronic Obstructive Pulmonary Disease (COPD) is a common, complex disease and a major cause of morbidity and mortality. Although multiple genetic determinants of COPD have been implicated by genome-wide association studies (GWAS), the pathophysiologic significance of these associations remains largely unknown. From a COPD protein-protein interaction network module, we selected a network path between two COPD GWAS genes for validation studies: FAM13A-AP3D1-CTGF-TGFB2. We find that TGFβ2, FAM13A, and AP3D1 (but not CTGF) form a cellular protein complex. Functional characterization suggests that this complex mediates the secretion of TGFβ2 through an AP-3-dependent pathway, with FAM13A acting as a negative regulator by targeting a late stage of this transport that involves the dissociation of coat-cargo interaction. Moreover, we find that TGFβ2 is a transmembrane protein that engages the AP-3 complex for delivery to the late endosomal compartments for subsequent secretion through exosomes. These results identify a pathophysiologic context that unifies the biological network role of two COPD GWAS proteins and reveal novel mechanisms of cargo transport through an intracellular pathway.

Global Protease Activity Profiling Identifies HER2-Driven Proteolysis in Breast Cancer

Differential expression of extracellular proteases and endogenous protease inhibitors has been associated with distinct molecular subtypes of breast cancer. However, due to the tight post-translational regulation of protease activity, protease expression-level data alone are not sufficient to understand the role of proteases in malignant transformation. Therefore, we hypothesized that global profiles of extracellular protease activity could more completely reflect differences observed at the transcriptional level in breast cancer and that subtype-associated protease activity may be leveraged to identify specific proteases that play a functional role in cancer signaling. Here, we used a global peptide library-based approach to profile the activities of proteases within distinct breast cancer subtypes. Analysis of 3651 total peptide cleavages from a panel of well-characterized breast cancer cell lines demonstrated differences in proteolytic signatures between cell lines. Cell line clustering based on protease cleavages within the peptide library expanded upon the expected classification derived from transcriptional profiling. An isogenic cell line model developed to further interrogate proteolysis in the HER2 subtype revealed a proteolytic signature consistent with activation of TGF-β signaling. Specifically, we determined that a metalloprotease involved in TGF-β signaling, BMP1, was upregulated at both the protein (2-fold, P = 0.001) and activity (P = 0.0599) levels. Inhibition of BMP1 and HER2 suppressed invasion of HER2-expressing cells by 35% (P < 0.0001), compared to 15% (P = 0.0086) observed in cells where only HER2 was inhibited. In summary, through global identification of extracellular proteolysis in breast cancer cell lines, we demonstrate subtype-specific differences in protease activity and elucidate proteolysis associated with HER2-mediated signaling.

Targeting RGD-binding integrins as an integrative therapy for diabetic retinopathy and neovascular age-related macular degeneration

Integrins are a class of transmembrane receptors that are involved in a wide range of biological functions. Dysregulation of integrins has been implicated in many pathological processes and consequently, they are attractive therapeutic targets. In the ophthalmology arena, there is extensive evidence suggesting that integrins play an important role in diabetic retinopathy (DR), age-related macular degeneration (AMD), glaucoma, dry eye disease and retinal vein occlusion. For example, there is extensive evidence that arginyl-glycyl-aspartic acid (Arg-Gly-Asp; RGD)-binding integrins are involved in key disease hallmarks of DR and neovascular AMD (nvAMD), specifically inflammation, vascular leakage, angiogenesis and fibrosis. Based on such evidence, drugs that engage integrin-linked pathways have received attention for their potential to block all these vision-threatening pathways. This review focuses on the pathophysiological role that RGD-binding integrins can have in complex multifactorial retinal disorders like DR, diabetic macular edema (DME) and nvAMD, which are leading causes of blindness in developed countries. Special emphasis will be given on how RGD-binding integrins can modulate the intricate molecular pathways and regulate the underlying pathological mechanisms. For instance, the interplay between integrins and key molecular players such as growth factors, cytokines and enzymes will be summarized. In addition, recent clinical advances linked to targeting RGD-binding integrins in the context of DME and nvAMD will be discussed alongside future potential for limiting progression of these diseases.

Targeting TGFβ signal transduction for cancer therapy

Transforming growth factor-β (TGFβ) family members are structurally and functionally related cytokines that have diverse effects on the regulation of cell fate during embryonic development and in the maintenance of adult tissue homeostasis. Dysregulation of TGFβ family signaling can lead to a plethora of developmental disorders and diseases, including cancer, immune dysfunction, and fibrosis. In this review, we focus on TGFβ, a well-characterized family member that has a dichotomous role in cancer progression, acting in early stages as a tumor suppressor and in late stages as a tumor promoter. The functions of TGFβ are not limited to the regulation of proliferation, differentiation, apoptosis, epithelial-mesenchymal transition, and metastasis of cancer cells. Recent reports have related TGFβ to effects on cells that are present in the tumor microenvironment through the stimulation of extracellular matrix deposition, promotion of angiogenesis, and suppression of the anti-tumor immune reaction. The pro-oncogenic roles of TGFβ have attracted considerable attention because their intervention provides a therapeutic approach for cancer patients. However, the critical function of TGFβ in maintaining tissue homeostasis makes targeting TGFβ a challenge. Here, we review the pleiotropic functions of TGFβ in cancer initiation and progression, summarize the recent clinical advancements regarding TGFβ signaling interventions for cancer treatment, and discuss the remaining challenges and opportunities related to targeting this pathway. We provide a perspective on synergistic therapies that combine anti-TGFβ therapy with cytotoxic chemotherapy, targeted therapy, radiotherapy, or immunotherapy.

The chemical environmental pollutants BPA and BPS induce alterations of the proteomic profile of different phenotypes of human breast cancer cells: A proposed interactome

Breast cancer is one of the most common malignancies and the second leading cause of death in women. Despite efforts for its early detection, its worldwide incidence continues to increase. Thus, identification of risk factors for its development and new targets for its therapy are of vital importance. Environmental pollutants derived from human activity have been associated with predisposition to the development of cancer. Bisphenol A (BPA) is an endocrine disruptor compound (EDC) widely used in the manufacture of polycarbonates, and it has affinity for the estrogen receptor (ER). Scientific evidence has proposed an association between increased incidence of breast cancer and BPA exposure at lower doses. Among worldwide concerns with BPA exposure, different industries proceeded to replace BPA with analogs such as bisphenol S (BPS), which is now employed in products labelled as BPA-free. Nevertheless, recent studies exhibit that its exposure results in altered mammary gland development and morphogenesis; and promotes breast cancer cell proliferation. Of note, most of the effects of both BPA and BPS have been performed in estrogen-dependent breast cancer models. However, gaps in knowledge still exist on the roles and mechanisms that both compounds, specifically BPS, may play in cancer initiation and development in hormone-dependent and other types of breast cancer. Thus, the aim of the present study was to deepen the understanding of biological targets modulated by these ubiquitous pollutants in different breast cancer cell lines, representing two scenarios of this pathology: hormone-dependent and hormone-independent breast cancer. Results point out that both compounds induced proliferation in ER positive cells, not showing this effect in the ER-negative breast cancer cells. Different targets modified at the proteomic level in both breast cancer scenarios were also identified. Stem cell markers (eg. CD44) and invasion proteins (eg. MMP-14) were importantly increased by BPA and BPS in ER-positive breast cancer cells. In contrast, growth factors and associated receptors such as EGFR and TGF-β were induced by BPS in the ER-negative breast cancer cells; both pollutants induced an increase of vascular endothelial growth factor (VEGF) protein secretion. This finding suggests that the use of BPS must be considered with more caution than BPA, since it can act independently of the presence of the hormonal receptor. These findings show new evidence that BPA and BPS exposure can contribute to breast cancer development and progression. Our results suggest that both BPA and BPS must be considered equally as outstanding risk factors for this pathology.

Inhibiting Sialidase-Induced TGF-β1 Activation Attenuates Pulmonary Fibrosis in Mice

The active form of transforming growth factor-β1 (TGF-β1) plays a key role in potentiating fibrosis. TGF-β1 is sequestered in an inactive state by a latency-associated glycopeptide (LAP). Sialidases (also called neuraminidases (NEU)) cleave terminal sialic acids from glycoconjugates. The sialidase NEU3 is upregulated in fibrosis, and mice lacking Neu3 show attenuated bleomycin-induced increases in active TGF-β1 in the lungs and attenuated pulmonary fibrosis. Here we observe that recombinant human NEU3 upregulates active human TGF-β1 by releasing active TGF-β1 from its latent inactive form by desialylating LAP. Based on the proposed mechanism of action of NEU3, we hypothesized that compounds with a ring structure resembling picolinic acid might be transition state analogs and thus possible NEU3 inhibitors. Some compounds in this class showed nanomolar IC₅₀ for recombinant human NEU3 releasing active human TGF-β1 from the latent inactive form. The compounds given as daily 0.1-1-mg/kg injections starting at day 10 strongly attenuated lung inflammation, lung TGF-β1 upregulation, and pulmonary fibrosis at day 21 in a mouse bleomycin model of pulmonary fibrosis. These results suggest that NEU3 participates in fibrosis by desialylating LAP and releasing TGF-β1 and that the new class of NEU3 inhibitors are potential therapeutics for fibrosis. SIGNIFICANCE STATEMENT: The extracellular sialidase NEU3 appears to be a key driver of pulmonary fibrosis. The significance of this report is that 1) we show the mechanism (NEU3 desialylates the latency-associated glycopeptide protein that keeps the profibrotic cytokine transforming growth factor-β1 (TGF-β1) in an inactive state, causing active TGF-β1 release), 2) we then use the predicted NEU3 mechanism to identify nM IC₅₀ NEU3 inhibitors, and 3) these new NEU3 inhibitors are potent therapeutics in a mouse model of pulmonary fibrosis.

Porphyromonas gingivalis promotes progression of esophageal squamous cell cancer via TGFβ-dependent Smad/YAP/TAZ signaling

Microbial dysbiosis in the upper digestive tract is linked to an increased risk of esophageal squamous cell carcinoma (ESCC). Overabundance of Porphyromonas gingivalis is associated with shorter survival of ESCC patients. We investigated the molecular mechanisms driving aggressive progression of ESCC by P. gingivalis. Intracellular invasion of P. gingivalis potentiated proliferation, migration, invasion, and metastasis abilities of ESCC cells via transforming growth factor-β (TGFβ)-dependent Drosophila mothers against decapentaplegic homologs (Smads)/Yes-associated protein (YAP)/Transcriptional coactivator with PDZ-binding motif (TAZ) activation. Smads/YAP/TAZ/TEA domain transcription factor1 (TEAD1) complex formation was essential to initiate downstream target gene expression, inducing an epithelial-mesenchymal transition (EMT) and stemness features. Furthermore, P. gingivalis augmented secretion and bioactivity of TGFβ through glycoprotein A repetitions predominant (GARP) up-regulation. Accordingly, disruption of either the GARP/TGFβ axis or its activated Smads/YAP/TAZ complex abrogated the tumor-promoting role of P. gingivalis. P. gingivalis signature genes based on its activated effector molecules can efficiently distinguish ESCC patients into low- and high-risk groups. Targeting P. gingivalis or its activated effectors may provide novel insights into clinical management of ESCC.

The circEPSTI1/mir-942-5p/LTBP2 axis regulates the progression of OSCC in the background of OSF via EMT and the PI3K/Akt/mTOR pathway

Oral squamous cell carcinoma (OSCC) in the background of oral submucous fibrosis (OSF) caused by areca nut chewing has a high incidence in Asia-Pacific countries. However, the molecular mechanism remains unclear. Here, we performed circRNA microarray analysis to screen the circRNA expression profiles in OSCC and OSF. We identified circEPSTI1 as a circRNA with consistent, sequential upregulation from normal buccal mucosa (NBM) to OSF to OSCC. Functionally, circEPSTI1 significantly promoted OSCC cell proliferation and invasion, as evidenced by the CCK8, colony formation, wound healing, and transwell assays with circEPSTI1 overexpression and silencing. OSCC patients with circEPSTI1^high status exhibited poor prognoses. CircEPSTI1 sponged miR-942-5p and accelerated epithelial-mesenchymal transition (EMT) to increase LTBP2 expression in OSCC through phosphorylation of PI3K/Akt/mTOR signaling pathway components. Blocking the PI3K/Akt/mTOR signaling pathway with the dual PI3k/mTOR inhibitor BEZ235 reversed OSCC progression induced by overexpression of circEPSTI1 and LTBP2. Collectively, these results indicate that the circEPSTI1/miR-942-5p/LTBP2 axis affects OSCC cell proliferation and invasion via the acceleration of EMT and the phosphorylation of PI3K/Akt/mTOR signaling pathway components. CircEPSTI1 may be an independent diagnostic and prognostic marker and a potential therapeutic target for OSCC patients with OSF.

Targeting all transforming growth factor-β isoforms with an Fc chimeric receptor impairs tumor growth and angiogenesis of oral squamous cell cancer

Tumor progression is governed by various growth factors and cytokines in the tumor microenvironment (TME). Among these, transforming growth factor-β (TGF-β) is secreted by various cell types residing in the TME and promotes tumor progression by inducing the epithelial-to-mesenchymal transition (EMT) of cancer cells and tumor angiogenesis. TGF-β comprises three isoforms, TGF-β1, -β2, and -β3, and transduces intracellular signals via TGF-β type I receptor (TβRI) and TGF-β type II receptor (TβRII). For the purpose of designing ligand traps that reduce oncogenic signaling in the TME, chimeric proteins comprising the ligand-interacting ectodomains of receptors fused with the Fc portion of immunoglobulin are often used. For example, chimeric soluble TβRII (TβRII-Fc) has been developed as an effective therapeutic strategy for targeting TGF-β ligands, but several lines of evidence indicate that TβRII-Fc more effectively traps TGF-β1 and TGF-β3 than TGF-β2, whose expression is elevated in multiple cancer types. In the present study, we developed a chimeric TGF-β receptor containing both TβRI and TβRII (TβRI-TβRII-Fc) and found that TβRI-TβRII-Fc trapped all TGF-β isoforms, leading to inhibition of both the TGF-β signal and TGF-β-induced EMT of oral cancer cells, whereas TβRII-Fc failed to trap TGF-β2. Furthermore, we found that TβRI-TβRII-Fc suppresses tumor growth and angiogenesis more effectively than TβRII-Fc in a subcutaneous xenograft model of oral cancer cells with high TGF-β expression. These results suggest that TβRI-TβRII-Fc may be a promising tool for targeting all TGF-β isoforms in the TME.

Role of extra cellular proteins in gastric cancer progression and metastasis: an update

Background

Gastric cancer (GC) is one of the most common cancers in the world with a high ratio of mortality. Regarding the late diagnosis, there is a high ratio of distant metastasis among GC cases. Despite the recent progresses in therapeutic modalities, there is not still an efficient therapeutic method to increase survival rate of metastatic GC cases.

Main body

Apart from the various intracellular signaling pathways which are involved in tumor cell migration and metastasis, the local microenvironment is also a critical regulator of tumor cell migration. Indeed, the intracellular signaling pathways also exert their final metastatic roles through regulation of extra cellular matrix (ECM). Therefore, it is required to assess the role of extra cellular components in biology of GC.

Conclusion

In the present review, we summarize 48 of the significant ECM components including 17 ECM modifying enzymes, seven extracellular angiogenic factors, 13 cell adhesion and cytoskeletal organizers, seven matricellular proteins and growth factors, and four proteoglycans and extra cellular glycoproteins. This review paves the way of determination of a specific extra cellular diagnostic and prognostic panel marker for the GC patients.

High dose vitamin D exacerbates central nervous system autoimmunity by raising T-cell excitatory calcium

Poor vitamin D status is associated with a higher relapse rate and earlier disability in multiple sclerosis. Based on these associations, patients with multiple sclerosis are frequently supplemented with the vitamin D precursor cholecalciferol, although it is unclear whether this regimen is of therapeutic benefit. To model consequences of this common practice, mice were fed for more than 3 months with a low, medium or high dose of cholecalciferol, representative of vitamin D deficiency, modest and disproportionally high supplementation, respectively, in patients with multiple sclerosis. Compared to vitamin D-deprived mice, its moderate supplementation reduced the severity of subsequent experimental autoimmune encephalomyelitis, which was associated with an expansion of regulatory T cells. Direct exposure of murine or human T cells to vitamin D metabolites inhibited their activation. In contrast, mice with 25-(OH) vitamin D levels above 200 nmol/l developed fulminant experimental autoimmune encephalomyelitis with massive CNS infiltration of activated myeloid cells, Th1 and Th17 cells. When dissecting this unexpected outcome, we observed that high, but not medium dose vitamin D had caused mild hypercalcaemia, which rendered T cells more prone to pro-inflammatory activation. Exposing murine or human T cells to equivalent calcium concentrations in vitro enhanced its influx, triggering activation, upregulation of pro-inflammatory gene products and enhanced transmigration across a blood-brain barrier model. These findings suggest that vitamin D at moderate levels may exert a direct regulatory effect, while continuous high dose vitamin D treatment could trigger multiple sclerosis disease activity by raising mean levels of T-cell excitatory calcium.

Upregulation of Sortilin, a Lysosomal Sorting Receptor, Corresponds with Reduced Bioavailability of Latent TGFβ in Mucolipidosis II Cells

Mucolipidosis II (ML-II) is a lysosomal disease caused by defects in the carbohydrate-dependent sorting of soluble hydrolases to lysosomes. Altered growth factor signaling has been identified as a contributor to the phenotypes associated with ML-II and other lysosomal disorders but an understanding of how these signaling pathways are affected is still emerging. Here, we investigated transforming growth factor beta 1 (TGFβ1) signaling in the context of ML-II patient fibroblasts, observing decreased TGFβ1 signaling that was accompanied by impaired TGFβ1-dependent wound closure. We found increased intracellular latent TGFβ1 complexes, caused by reduced secretion and stable localization in detergent-resistant lysosomes. Sortilin, a sorting receptor for hydrolases and TGFβ-related cytokines, was upregulated in ML-II fibroblasts as well as GNPTAB-null HeLa cells, suggesting a mechanism for inappropriate lysosomal targeting of TGFβ. Co-expression of sortilin and TGFβ in HeLa cells resulted in reduced TGFβ1 secretion. Elevated sortilin levels correlated with normal levels of cathepsin D in ML-II cells, consistent with a compensatory role for this receptor in lysosomal hydrolase targeting. Collectively, these data support a model whereby sortilin upregulation in cells with lysosomal storage maintains hydrolase sorting but suppresses TGFβ1 secretion through increased lysosomal delivery. These findings highlight an unexpected link between impaired lysosomal sorting and altered growth factor bioavailability.

Transforming growth factor beta 1 (TGFβ1) plasmatic levels in breast cancer and neoplasia-free women: Association with patients' characteristics and TGFB1 haplotypes

Transforming growth factor beta 1 (TGFβ1) is a pleiotropic cytokine that acts in a context-dependent manner. In breast cancer (BC) this cytokine exerts subtype- and stage-specific roles, inhibiting poorly aggressive tumors while enhances the invasive potential of highly aggressive cancers. Single-nucleotide polymorphisms (SNPs) affecting TGFβ1 production largely reflect this pattern of association, but studies investigating systemic TGFβ1 levels in BC patients and their association with clinical features or SNPs produced conflicting conclusions. Therefore, the present work investigated plasmatic TGFβ1 levels through enzyme linked immunosorbent assay (ELISA) in 341 individuals previously genotyped for four TGFB1 SNPs [G-800A (rs1800468), C-509T (rs1800469), T29C (rs1800470) and G74C (rs1800471)], encompassing 184 neoplasia-free women with clinical information regarding health status, 113 treatment-free pre-surgery BC patients and 44 treated BC patients. Results have shown that TGFβ1 levels varied greatly in function of health status in neoplasia-free women, and disease-free individuals had higher TGFβ1 levels than both treatment-free or treated BC patients. There was no correlation between TGFβ1 with clinicopathological features in treatment-free BC general group, but it was negatively correlated with tumor size in luminal-B-HER2+ patients and with histopathological grade in triple-negative group. Also, TGFB1 ACTG haplotype (from G-800A to G74C) was associated with decreased TGFβ1 levels compared to the reference GCTG haplotype, and regression analyses showed that this association was independent of age, health status or BC diagnosis. In conclusion, several factors may influence TGFβ1 levels, and ACTG haplotype seems to be an important factor regulating TGFβ1 production.