Smad transcription factors

CUL4A exhibits tumor-suppressing role via regulation of HUWE1-mediated SMAD3 intracellular shuttling

Changes in cellular physiology and proteomic homeostasis accompanied the initiation and progression of colorectal cancer. Thus, ubiquitination represents a central regulatory mechanism in proteome dynamics. However, the complexity of the ubiquitinating network involved in carcinogenesis remains unclear. This study revealed the tumor-suppressive role of the ubiquitin ligase Cullin4A (CUL4A) in the intestine. We showed that simultaneous loss of CUL4A and hyperactivation of the Wnt pathway promotes tumor development in the distal colon. This tumor development is caused by an accumulation of the inactive SMAD3, a TGF-β pathway mediator. Depletion of CUL4A resulted in stabilization of HUWE1, which attenuated SMAD3 function. We showed a correlation between the intracellular localization of CUL4A and colorectal cancer progression, where nuclear CUL4A localization correlates with advanced colorectal cancer progression. In summary, we identified CUL4A as an important regulator of SMAD3 signal transduction competence in a HUWE1-dependent manner and demonstrated a critical role for the crosstalk between ubiquitination and the Wnt/TGF-β signaling pathways in gastrointestinal homeostasis.

Pre-existing DNA methylation signatures in the prefrontal cortex of alcohol-naïve nonhuman primates define neural vulnerability for future risky ethanol consumption

Alcohol use disorder (AUD) is a highly prevalent, complex, multifactorial and heterogeneous disorder, with 11 % and 30 % of adults meeting criteria for past-year and lifetime AUD, respectively. Identification of the molecular mechanisms underlying risk for AUD would facilitate effective deployment of personalized interventions. Studies using rhesus monkeys and rats, have demonstrated that individuals with low cognitive flexibility and a predisposition towards habitual behaviors show an increased risk for future heavy drinking. Further, low cognitive flexibility is associated with reduced dorsolateral prefrontal cortex (dlPFC) function in rhesus monkeys. To explore the underlying unique molecular signatures that increase risk for chronic heavy drinking, a genome-wide DNA methylation (DNAm) analysis of the alcohol-naïve dlPFC-A46 biopsy prior to chronic alcohol self-administration was conducted. The DNAm profile provides a molecular snapshot of the alcohol-naïve dlPFC, with mapped genes and associated signaling pathways that vary across individuals. The analysis identified 1,463 differentially methylated regions (DMRs) related to unique genes that were strongly associated with average ethanol intake consumed over 6 months of voluntary self-administration. These findings translate behavioral phenotypes into neural markers of risk for AUD, and hold promise for parallel discoveries in risk for other disorders involving impaired cognitive flexibility. SIGNIFICANCE: Alcohol use disorder (AUD) is a highly prevalent and heterogeneous disorder. Prevention strategies to accurately identify individuals with a high risk for AUD, would help reduce the prevalence, and severity of AUD. Our novel epigenomic analysis of the alcohol-naïve nonhuman primate cortex provides a molecular snapshot of the vulnerable brain, pointing to circuitry and molecular mechanisms associated with cortical development, synaptic functions, glutamatergic signaling and coordinated signaling pathways. With a complex disorder like AUD, having the ability to identify the molecular mechanisms underlying AUD risk is critical for better development of personalized effective treatments.

Smad4 and TGFβ1 dependent gene expression signatures in conditional intestinal adenoma, organoids and colorectal cancer

TGF-β ligands suppress growth yet can paradoxically and potently promote cancer invasion and metastasis depending on downstream pathway mutational context, such as loss of Mothers against decapentaplegic homolog 4 (Smad4). Here, we characterised phenotypes and associated gene expression signatures in conditional murine intestinal adenoma with and without Smad4. Conditional Lgr5-CreERT2 activation in Apcfl/flSmad4fl/fl mice resulted in homozygote floxed alleles (ApcΔ/ΔSmad4Δ/Δ) and adenoma formation. The adenoma phenotype was discordant, with reduced small intestinal adenoma burden yet development of large non-metastatic caecal adenoma with nuclear localisation of phospho-Smad2/3. Derived ApcΔ/ΔSmad4Δ/Δ adenoma organoids resisted TGF-β1 dose dependent growth arrest and cell death (IC50 534 pM) compared to ApcΔ/ΔSmad4+/+ (IC50 24 pM). TGF-β1 (390 pM) altered adenoma bulk mRNA expression most significantly for Id1low and Spp1high in ApcΔ/ΔSmad4Δ/Δ. Single cell RNAseq of caecal adenoma identified expansion of Lgr5low, Pak3high and Id1low progenitor populations in ApcΔ/ΔSmad4Δ/Δ. Of the 76 Smad4 and TGF-β1 dependent genes identified in Apcfl/flSmad4fl/fl adenoma organoids, only 7 human equivalent genes were differentially expressed in SMAD4 mutated colorectal cancer (TCGA cohorts), including ID1low. SMAD4low, ID1low SPP1high and PAK3high all correlated with poorer survival. Murine adenoma identified Smad4 dependent gene expression signatures that require further evaluation as functional biomarker classifiers of SMAD4 mutated cancer subtypes.

Novel effects of reverse transcriptase inhibitor supplementation in skeletal muscle of old mice

Aging is the primary risk factor for the development of many chronic diseases, including dementias, cardiovascular disease, and diabetes. There is significant interest in identifying novel "geroprotective" agents, including by repurposing existing drugs, but such treatments may affect organ systems differently. One current example is the nucleoside reverse transcriptase inhibitor 3TC, which has been increasingly studied as a potential gerotherapeutic. Recent data suggest that 3TC may reduce inflammation and improve cognitive function in older mice; however, the effects of 3TC on other tissues in aged animals are less well characterized. Here, we use transcriptomics (RNA-seq) and targeted metabolomics to investigate the influence of 3TC supplementation on skeletal muscle in older mice. We show that 3TC 1) does not overtly affect muscle mass or functional/health markers, 2) largely reverses age-related changes in gene expression and metabolite signatures, and 3) is potentially beneficial for mitochondrial function in old animals via increases in antioxidant enzymes and decreases in mitochondrial reactive oxygen species. Collectively, our results suggest that, in addition to its protective effects in other tissues, 3TC supplementation does not have adverse effects in aged muscle and may even protect muscle/mitochondrial health in this context.NEW & NOTEWORTHY Recent studies suggest that the nucleoside reverse transcriptase inhibitor 3TC may improve brain health and cognitive function in old mice, but its effects on other aging tissues have not been comprehensively studied. This is the first study to use a multiomics approach to investigate the effects of 3TC treatment on skeletal muscle of old mice. The results suggest that 3TC reverses age-related transcriptomic and metabolite signatures and is potentially beneficial for mitochondrial function in aged muscle.

Optogenetic control of Nodal signaling patterns

A crucial step in early embryogenesis is the establishment of spatial patterns of signaling activity. Tools to perturb morphogen signals with high resolution in space and time can help reveal how embryonic cells decode these signals to make appropriate fate decisions. Here, we present new optogenetic reagents and an experimental pipeline for creating designer Nodal signaling patterns in live zebrafish embryos. Nodal receptors were fused to the light-sensitive heterodimerizing pair Cry2/CIB1N, and the type II receptor was sequestered to the cytosol. The improved optoNodal2 reagents eliminate dark activity and improve response kinetics, without sacrificing dynamic range. We adapted an ultra-widefield microscopy platform for parallel light patterning in up to 36 embryos, and demonstrated precise spatial control over Nodal signaling activity and downstream gene expression. Patterned Nodal activation drove precisely controlled internalization of endodermal precursors. Furthermore, we used patterned illumination to generate synthetic signaling patterns in Nodal signaling mutants, rescuing several characteristic developmental defects. This study establishes an experimental toolkit for systematic exploration of Nodal signaling patterns in live embryos.

The role of deubiquitinases in cardiovascular diseases: mechanisms and therapeutic implications

Cardiovascular diseases (CVDs) have become the leading cause of death globally, surpassing infectious diseases and other chronic illnesses. The incidence and mortality rates of CVDs are rising worldwide, posing a key challenge in public health. The ubiquitination system is a vast and complex. It is an important post-translational modification that plays a crucial role in various cellular processes. Deubiquitination is catalyzed by deubiquitinases (DUBs), which remove ubiquitin (Ub) from ubiquitinated proteins, thereby reversing the ubiquitination process. DUBs play an important role in many biological processes, such as DNA repair, cell metabolism, differentiation, epigenetic regulation, and protein stability control. They also participate in the regulation of many signaling pathways associated with the development and progression of CVDs. In this review, we primarily focus on the role of DUBs in various key pathological mechanisms of atherosclerosis (AS), such as foam cell formation, vascular remodeling (VR), endothelial-to-mesenchymal transition (End-MT), and clonal hematopoiesis (CH). In the heart, we summarize the involvement of DUBs in diseases and pathological processes, including heart failure (HF), myocardial infarction (MI), myocardial hypertrophy (MH) and ischemia/reperfusion (I/R) injury. Additionally, we also explore the diabetic cardiomyopathy (DCM) and the use of doxorubicin-induced cardiotoxicity in clinical settings. A comprehensive understanding of deubiquitination may provide new insights for the treatment and drug design of CVDs.

Towards an integrated view and understanding of embryonic signalling during murine gastrulation

At the onset of mammalian gastrulation, secreted signalling molecules belonging to the Bmp, Wnt, Nodal and Fgf signalling pathways induce and pattern the primitive streak, marking the start for the cellular rearrangements that generate the body plan. Our current understanding of how signalling specifies and organises the germ layers in three dimensions, was mainly derived from genetic experimentation using mouse embryos performed over many decades. However, the exact spatiotemporal sequence of events is still poorly understood, both because of a lack of tractable models that allow for real time visualisation of signalling and differentiation and because of the molecular and cellular complexity of these early developmental events. In recent years, a new wave of in vitro embryo models has begun to shed light on the dynamics of signalling during primitive streak formation. Here we discuss the similarities and differences between a widely adopted mouse embryo model, termed gastruloids, and real embryos from a signalling perspective. We focus on the gene regulatory networks that underlie signalling pathway interactions and outline some of the challenges ahead. Finally, we provide a perspective on how embryo models may be used to advance our understanding of signalling dynamics through computational modelling.

The Link Between TGF-β Signaling and Chromatin Dynamics Takes an Unexpected Path

The TGF-β/BMP signaling superfamily plays critical roles in regulating a wide range of physiological and pathological processes. A recent study on Tgfbr1 function during mouse embryonic development found that, in the absence of this gene, the primordium of the external genitalia changes its fate, forming an additional set of hindlimbs and resulting in the so-called "six-legged" mice. Analysis of these embryos demonstrated that Tgfbr1 induces global remodeling of chromatin accessibility, establishing distinct regulatory elements that other morphogenetic factors use to drive either hindlimb or genital development. While global changes in chromatin structure have been previously associated with TGF-β signaling, the alterations seen in six-legged embryos differ significantly from previously described mechanisms. In this review, I discuss these distinctions and underscore the importance of studying biological processes within their natural tissue context, where essential tissue interactions are preserved.

Genome-wide association study applied to prolificacy in Santa Inês sheep

This study aimed to identify genomic regions associated with prolificacy in Santa Inês sheep raised in tropical conditions. The prolificacy of the dam was defined as single (only one lamb born per ewe per lambing) or multiple (more than one animal born per ewe per lambing). After quality control of phenotypic data, 1584 lambing records of 715 females occurred between the years 2000 and 2018 were used. The animals were genotyped with the OvineSNP50 BeadChip panel (Illumina Inc.). After quality control of genomic data, information of 46,714 SNPs and 388 samples and females was used for the subsequent analyses. The single-step GWAS (ssGWAS) methodology was used to estimate the effects of genetic markers and their association with the prolificacy. A total of 21 windows of 10 adjacent SNPs that explained at least 0.5% of the additive genetic variance for prolificacy were identified. In such regions, genes associated with different reproductive functions in the female were found: CACNA1E, NTRK1, PLCH1, SMAD3, CENPF, TOPBP1, IL33, DRD2, MID1, HCCS, and ARHGAP6. Some candidate regions related to prolificacy harbor genes that were not previously described and genes without known functions. These results can help to identify genes associated with prolificacy and could be used in genomic reproductive studies on prolificacy, as well as in the selection of the most prolific ewes in the population.

Suppression of TGF-β/SMAD signaling by an inner nuclear membrane phosphatase complex

Cytokines of the TGF-β superfamily control essential cell fate decisions via receptor regulated SMAD (R-SMAD) transcription factors. Ligand-induced R-SMAD phosphorylation in the cytosol triggers their activation and nuclear accumulation. We determine how R-SMADs are inactivated by dephosphorylation in the cell nucleus to counteract signaling by TGF-β superfamily ligands. We show that R-SMAD dephosphorylation is mediated by an inner nuclear membrane associated complex containing the scaffold protein MAN1 and the CTDNEP1-NEP1R1 phosphatase. Structural prediction, domain mapping and mutagenesis reveals that MAN1 binds independently to the CTDNEP1-NEP1R1 phosphatase and R-SMADs to promote their inactivation by dephosphorylation. Disruption of this complex causes nuclear accumulation of R-SMADs and aberrant signaling, even in the absence of TGF-β ligands. These findings establish CTDNEP1-NEP1R1 as the R-SMAD phosphatase, reveal the mechanistic basis for TGF-β signaling inactivation and highlight how this process is disrupted by disease-associated MAN1 mutations.

Tricellulin facilitates colorectal cancer metastasis through activation of the TGFβ/SMAD2/3 signalling pathway

Background

Tricellulin belongs to the TAMP family of proteins and is primarily localized at the tricellular tight junctions. While its role in the progression of cancer has been reported, its importance in the progression of colorectal cancer (CRC) remains unclear.

Objective

This study aimed to determine the function and mechanism of tricellulin in CRC progression.

Methods

The proteins expression in cells and/or tissues was determined by Western blot, immunohistochemistry staining, and/or RT-qPCR analyses. The biological functions of tricellulin were investigated through in vitro assays (CCK-8, Transwell migration, and colony formation assays) and in vivo xenograft models. Tricellulin was significantly upregulated in CRC tissues compared to adjacent normal tissues. The expression of tricellulin was correlated with poor prognosis in patients with CRC.

Results

In vitro assays showed that tricellulin enhanced CRC cell proliferation, migration, and invasion. Mechanistically, tricellulin activated the TGFb1/SMAD2/3 pathway, while TGFb1 reciprocally controlled the expression of tricellulin. Also, tricellulin promotes CRC cell migration/invasion through EMT. In vivo models confirmed that the overexpression of tricellulin facilitated tumor growth and activated the TGFb1/ SMAD2/3 pathway in CRC.

Conclusion

Our findings demonstrate thatTricellulin promotes the metastasis of colorectal cancer by activating the TGF-β/SMAD2/3 signaling pathway, and TGF-β1 can reciprocally regulate the expression of tricellulin.We have revealed a novel mechanism by which tricellulin forms a positive feedback loop to promote the growth and metastasis of CRC. This mechanism provides novel insights into CRC progression and suggests potential therapeutic targets.

Exploring the Role of the TGF-β Signaling Pathway in Colorectal Precancerous Polyps Biochemical Genetics

Colorectal cancer (CRC) is an important public health issue and is the third most common cancer, accounting for approximately 10% of all cancer cases worldwide. CRC results from the accumulation of multiple genetic and epigenetic alterations in the normal epithelial cells of the colon and rectum, leading to the development of colorectal polyps and invasive carcinomas. The transforming growth factor-beta (TGF-β) pathway is regulated in many diseases, such as cancer. This factor can show tumor suppressant function in the early stages in healthy and cancer cells. It can be regulated and affected by different factors, including noncoding RNAs, which are the remarkable regulators for this pathway. The most prominent functions of this factor are cell cycle arrest and apoptosis in cancer cells. However, activating at the final stages of the cell cycle can cause tumor metastasis. Thus, the dual function of TGF-β and the pleiotropic nature of this signaling make it a crucial challenge for cancer treatment. Accurately studying the TGF-β signaling pathway is critical to determine its role. One of the roles of TGF-β signaling is its significant effect on colorectal polyp malignancy and cancer. In this article, we review the published scientific papers regarding the TGF-β signaling pathway, its related genes, and their contribution to precancerous conditions and colorectal cancer progression. The complex interaction of the TGF-β signaling pathway with noncoding RNAs, such as lncRNA TUG1 and miR-21, significantly influences colorectal polyp and cancer progression. Identifying dysregulated TGF-β-related noncoding RNAs offers promising therapeutic avenues for colorectal cancer. Comprehending TGF-β's connection to other molecular mechanisms is crucial for advancing effective therapeutic strategies.

Receptor-regulated smads (R-Smads) in the liver fluke Fasciola gigantica: Characterization, comparative sequence analysis, and life stage-specific expression

The transforming growth factor-beta (TGF-β) signaling pathway is a key conserved developmental pathway, demonstrating remarkable conservation in its components, structures, and functions across diverse animal species. This study presents a comprehensive characterization and comparative analysis of receptor-regulated Smads (R-Smads) in Fasciola gigantica, a major parasite affecting cattle, buffalo, and ruminants in tropical regions. Four R-Smads were identified: FgSmad1/5, FgSmad2, FgSmad3, and FgSmad8. Full-length cDNAs for these R-Smads, isolated using the rapid amplification of cDNA ends (RACE) approach, were 3348, 3010, 5172, and 1991 bp in length, encoding proteins of 464, 506, 678, and 404 amino acids, respectively. FgSmad1/5 and FgSmad8 were classified as bone morphogenetic protein (BMP)-specific R-Smads (BR-Smads) due to their conserved signature motifs and similarity to those found in parasitic platyhelminths and mammalian hosts. Conversely, FgSmad2 and FgSmad3 were identified as TGF-β/activin-specific R-Smads (AR-Smads), displaying a distinctive pattern of conserved motifs commonly observed among trematode parasites. Notably, FgSmad2 exhibited an atypical feature for R-Smads, as it lacked the MH1 domain. The expressions of F. gigantica R-Smad genes were observed across all developmental stages, with the highest levels of most R-Smads occurring in the unembryonated egg stage (primarily BR-Smads) and the metacercaria stage (predominantly AR-Smads), underscoring a significant shift in TGF-β and BMP signaling dynamics during development. These findings greatly advance our understanding of R-Smad proteins within the TGF-β signaling pathway of F. gigantica and provide a solid foundation for future research into their roles and regulatory mechanisms.

Smad transcription factors as mediators of 7 transmembrane G protein-coupled receptor signalling

The Smad transcription factors are well known for their role at the core of transforming growth factor-β (TGF-β) signalling. However, recent evidence shows that the Smad transcription factors play a vital role downstream of other classes of receptors including G protein-coupled receptors (GPCR). The versatility of Smad transcription factors originated from the two regions that can be differently activated by the TGF-β receptor superfamily or through the recruitment of intracellular kinases stimulated by other receptors classes such as GPCRs. The classic GPCR signalling cascade is further expanded to conditional adoption of the Smad transcription factor under the stimulation of Akt, demonstrating the unique involvement of the Smad transcription factor in GPCR signalling pathways in disease environments. In this review, we provide a summary of the signalling pathways of the Smad transcription factors as an important downstream mediator of GPCRs, presenting exciting opportunities for discovering new therapeutic targets for diseases.

Oligodendrocyte precursor cells establish regulatory contacts with the soma of active neurons

Oligodendrocyte precursor cells (OPCs) can generate myelinating oligodendrocytes life-long, a process that is dependent on neuronal activity. However, it is possible that OPCs have additional functions, influencing neuronal functions directly. We have used a mouse genetic model of juvenile seizures and chemical induction of neuronal activity to examine the morphological and molecular changes in OPCs around activated principal neurons. We found an increase in process extension of OPCs specifically toward the soma of activated neurons. Moreover, we found that the close proximity of OPC processes around neurons expressing the immediate early gene c-Fos decreased the calcium transients in these neurons, indicating a regulative function of OPCs. Analyses of transcriptome and chromatin accessibility revealed significant changes in genes involved in transforming growth factor beta (TGFβ) signaling. Extracellular matrix genes, particularly those encoding type VI collagen, an established binding partner for the OPC surface protein NG2, was increased around active neurons. Our findings indicate that OPCs are an integral part of the neural network and may help to decrease the activity of neurons that have previously been over-excited, in order to protect these neurons.

Modeling SMAD2 Mutations in Induced Pluripotent Stem Cells Provides Insights Into Cardiovascular Disease Pathogenesis

BACKGROUND

SMAD2 is a coregulator that binds a variety of transcription factors in human development. Heterozygous SMAD2 loss-of-function and missense variants are identified in patients with congenital heart disease (CHD) or arterial aneurysms. Mechanisms that cause distinct cardiovascular phenotypes remain unknown. We aimed to define transcriptional and epigenetic effects of SMAD2 variants and their role in CHD. We also assessed the function of SMAD2 missense variants of uncertain significance.

METHODS AND RESULTS

Rare SMAD2 variants (minor allele frequency ≤10-5) were identified in exome sequencing of 11 336 participants with CHD. We constructed isogenic induced pluripotent stem cells with heterozygous or homozygous loss-of-function and missense SMAD2 variants identified in CHD probands. Wild-type and mutant induced pluripotent stem cells were analyzed using bulk RNA sequencing, chromatin accessibility (Assay for Transposase-Accessible Chromatin With Sequencing), and integrated with published SMAD2/3 chromatin immunoprecipitation data. Cardiomyocyte differentiation and contractility were evaluated. Thirty participants with CHD had heterozygous loss-of-function or missense SMAD2 variants. SMAD2 haploinsufficiency altered chromatin accessibility at promoters and dysregulated expression of 385 SMAD regulated genes, including 10 CHD-associated genes. Motifs enriched in differential Assay for Transposase-Accessible Chromatin peaks predicted that SMAD2 haploinsufficiency disrupts interactions with transcription factors NANOG (homeobox protein NANOG), ETS, TEAD3/4 (transcriptional enhanced associate domain 3/4), CREB1 (cAMP response element binding protein 1), and AP1 (activator protein 1). Compared with SMAD2-haploinsufficient cells, induced pluripotent stem cells with R114C or W274C variants exhibited distinct and shared chromatin accessibility and transcription factor binding changes.

CONCLUSIONS

SMAD2 haploinsufficiency disrupts transcription factor binding and chromatin interactions critical for cardiovascular development. Differences between the molecular consequences of loss-of-function and missense variants likely contribute to phenotypic heterogeneity. These findings indicate opportunities for molecular analyses to improve reclassification of SMAD2 variants of uncertain clinical significance.

Role of TGF-β/SMAD/YAP/TAZ signaling in skeletal muscle fibrosis

Skeletal muscle fibrosis is strongly associated with the differentiation of its resident multipotent fibro/adipogenic progenitors (FAPs) toward the myofibroblast phenotype. Although transforming growth factor type β (TGF-β) signaling is well-known for driving FAPs differentiation and fibrosis, due to its pleiotropic functions its complete inhibition is not suitable for treating fibrotic disorders such as muscular dystrophies. Here, we describe that TGF-β operates through the mechanosensitive transcriptional regulators Yes-associated protein (YAP)/ transcriptional coactivator with PDZ-binding motif (TAZ) to determine the myofibroblast fate of FAPs and skeletal muscle fibrosis. Spatial transcriptomics analyses of dystrophic and acute injured muscles showed that areas with active fibrosis and TGF-β signaling displayed high YAP/TAZ activity. Using a TGF-β-driven fibrotic mouse model, we found that activation of YAP/TAZ in activated FAPs is associated with the fibrotic process. Mechanistically, primary culture of FAPs reveals the remarkable ability of TGF-β1 to activate YAP/TAZ through its canonical SMAD3 pathway. Moreover, inhibition of YAP/TAZ, either by disrupting its activity (with Verteporfin) or cellular mechanotransduction (with the Rho inhibitor C3 or soft matrices), decreased TGF-β1-dependent FAPs differentiation into myofibroblasts. In vivo, administration of Verteporfin in mice limits the deposition of collagen and fibronectin, and the activation of FAPs during the development of fibrosis. Overall, our work provides robust evidence for considering YAP/TAZ as a potential target in muscular fibroproliferative disorders.NEW & NOTEWORTHY The understanding of the nuclear factors governing the differentiation of muscular fibro/adipogenic progenitors (FAPs) into myofibroblasts is in its infancy. Here, we comprehensively elucidate the status, regulation, and role of the mechanotransducers Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) in the muscular fibrotic process. Our findings reveal that inhibiting cellular mechanotransduction limits FAP differentiation and the extent of muscular fibrosis exerted by transforming growth factor type β (TGF-β). This research shed new lights on the molecular mechanisms dictating the cell fate of FAPs and the muscular fibrosis.

Bone morphogenetic protein (BMP) signaling determines neuroblastoma cell fate and sensitivity to retinoic acid

Retinoic acid (RA) is a standard-of-care neuroblastoma drug thought to be effective by inducing differentiation. Curiously, RA has little effect on primary human tumors during upfront treatment but can eliminate neuroblastoma cells from the bone marrow during post-chemo maintenance therapy-a discrepancy that has never been explained. To investigate this, we treat a large cohort of neuroblastoma cell lines with RA and observe that the most RA-sensitive cells predominantly undergo apoptosis or senescence, rather than differentiation. We conduct genome-wide CRISPR knockout screens under RA treatment, which identify bone morphogenic protein (BMP) signaling as controlling the apoptosis/senescence vs differentiation cell fate decision and determining RA's overall potency. We then discover that BMP signaling activity is markedly higher in neuroblastoma patient samples at bone marrow metastatic sites, providing a plausible explanation for RA's ability to clear neuroblastoma cells specifically from the bone marrow, by seemingly mimicking interactions between BMP and RA during normal development.

Stem cell-based embryo models: a tool to study early human development

How a mammalian fertilized egg acquires totipotency and develops into a full-term offspring is a fundamental scientific question. Human embryonic development is difficult to study due to limited resources, technical challenges and ethics. Moreover, the precise regulatory mechanism underlying early human embryonic development remains unknown. In recent years, the emergence of stem cell-based embryo models (SCBEM) provides the opportunity to reconstitute pre- to post-implantation development in vitro. These models to some extent mimic the embryo morphologically and transcriptionally, and thus may be used to study key events in mammalian pre- and post-implantation development. Many groups have successfully generated SCBEM of the mouse and human. Here, we provide a comparative review of the mouse and human SCBEM, discuss the capability of these models to mimic natural embryos and give a perspective on their potential future applications.

α-arbutin prevents UVA-induced skin photodamage via alleviating DNA damage and collagen degradation in NIH-3T3 cells

Ultraviolet radiation (UV) causes certain side effects to the skin, and their accumulation to a certain extent can lead to accelerated aging of the skin. Recent studies suggest that α-arbutin may be useful in various disorders such as hyperpigmentation disorders, wound healing, and antioxidant activity. However, the role of α-arbutin in skin photodamage is unclear. In this study, under UVA-induced photodamage conditions, α-arbutin treated mouse skin fibroblasts (NIH-3T3) can repair DNA damage and resist apoptosis by reducing the production of reactive oxygen species (ROS) and increasing the phosphorylation of glycogen synthase kinase 3 beta (GSK3β) to orchestra AKT/GSK3β pathway. Meanwhile, α-arbutin can also regulate collagen metabolism and facilitate the replenishment of collagen by targeting the phosphorylation of SMAD3 to mediate the TGFβ/SMAD pathway in NIH-3T3. In conclusion, we found that α-arbutin can mitigate the detrimental effects of skin photodamage induced by UVA irradiation, and provides a theoretical basis for the use of α-arbutin in the treatment of skin photodamage.

Portrait of WWP1: the current state in human cancer

WWP1, a member of the C2-WW-HECT E3 ligase family, is an E3 ubiquitin-protein ligase containing WW domains. This enzyme plays a critical role in regulating diverse cellular processes. Its expression is modulated by various factors and non-coding RNAs, resulting in ubiquitination that affects substrate protein degradation. WWP1 demonstrates a dual function, acting predominantly as an oncogene in tumors but occasionally as a tumor suppressor. This review summarizes WWP1's biological roles, therapeutic potential in oncology, upstream regulatory factors, and downstream substrates. It aims to promote research on WWP1's antitumor effects, improve understanding of its role in tumorigenesis, and support the development of targeted therapies.

Targeting Chondrocyte Hypertrophy as Strategies for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a common joint disease characterized by pain and functional impairment, which severely impacts the quality of life of middle-aged and elderly individuals. During normal bone development, chondrocyte hypertrophy is a natural physiological process. However, in the progression of OA, chondrocyte hypertrophy becomes one of its key pathological features. Although there is no definitive evidence to date confirming that chondrocyte hypertrophy is the direct cause of OA, substantial experimental data indicate that it plays an important role in the disease's pathogenesis. In this review, we first explore the mechanisms underlying chondrocyte hypertrophy in OA and offer new insights. We then propose strategies for inhibiting chondrocyte hypertrophy from the perspectives of targeting signaling pathways and tissue engineering, ultimately envisioning the future prospects of OA treatment.

SMAD5 as a novel gene for familial pulmonary arterial hypertension

Genetic diagnostic testing of 325 pulmonary arterial hypertension (PAH) patients using a PAH specific gene panel including 18 known PAH genes revealed mutations in 23%. Further PAH candidate genes were sequenced in the remaining patients exposing two SMAD5 variants, which were clinically and functionally characterized. We first recorded familial cosegregation and clinical parameters. Functional tests were performed following transient over-expression of the two SMAD5 variants in pulmonary artery smooth muscle cells (PASMCs). Expression of these variants was confirmed by quantitative PCR, Sanger sequencing, and Western blotting. Cell viability was evaluated using cell counting kit 8, cell proliferation by bromodeoxyuridine (BrdU), and apoptosis by annexin V assay. Both SMAD5 missense variants were absent in healthy controls and predicted to be pathogenic. The variant c.1175T>C p.(Leu392Pro) was identified in a heritable PAH patient and her healthy son. The mother had died of suspected PAH at age 42. The expression of this variant in PASMCs led to significantly higher cell viability due to higher proliferation in comparison with SMAD5 wild-type cells. The second variant c.277T>A p.(Trp93Arg) was identified in a patient with congenital heart disease associated PAH with a surgically repaired ventricular septal defect. Its expression led to significantly lower cell viability due to increased apoptosis in comparison with wild-type SMAD5 cells. Taking into account familial aggregation, clinical findings, and functional evidence, both variants could be classified as likely pathogenic. This is the first description of SMAD5 as a potential novel PAH gene for genetic diagnostic testing.

Broadening horizons: molecular mechanisms and disease implications of endothelial-to-mesenchymal transition

Endothelial-mesenchymal transition (EndMT) is defined as an important process of cellular differentiation by which endothelial cells (ECs) are prone to lose their characteristics and transform into mesenchymal cells. During EndMT, reduced expression of endothelial adhesion molecules disrupts intercellular adhesion, triggering cytoskeletal reorganization and mesenchymal transition. Numerous studies have proved that EndMT is a multifaceted biological event driven primarily by cytokines such as TGF-β, TNF-α, and IL-1β, alongside signaling pathways like WNT, Smad, MEK-ERK, and Notch. Nevertheless, the exact roles of EndMT in complicated diseases have not been comprehensively reviewed. In this review, we summarize the predominant molecular regulatory mechanisms and signaling pathways that contribute to the development of EndMT, as well as highlight the contributions of a series of imperative non-coding RNAs in curbing the initiation of EndMT. Furthermore, we discuss the significant impact of EndMT on worsening vasculature-related diseases, including cancer, cardiovascular diseases, atherosclerosis, pulmonary vascular diseases, diabetes-associated fibrotic conditions, and cerebral cavernous malformation, providing the implications that targeting EndMT holds promise as a therapeutic strategy to mitigate disease progression.

Mechanistic role for mTORC1 signaling in profibrotic toxicity of low-dose cadmium

Cadmium (Cd) is a toxic environmental metal that occurs naturally in food and drinking water. Cd is of increasing concern to human health due to its association with age-related diseases and long biological half-life. Previous studies show that low-dose Cd exposure via drinking water induces mechanistic target of rapamycin complex 1 (mTORC1) signaling in mice; however, the role of mTORC1 pathway in Cd-induced pro-fibrotic responses has not been established. In the present study, we used human lung fibroblasts to examine whether inhibiting the mTORC1 pathway prevents lung fibrosis signaling induced by low-dose Cd exposure. Results show that rapamycin, a pharmacological inhibitor of mTORC1, inhibited Cd-dependent phosphorylation of ribosomal protein S6, a downstream marker of mTORC1 activation. Rapamycin also decreased Cd-dependent increases in pro-fibrotic markers, α-smooth muscle actin, collagen 1α1 and fibronectin. Cd activated mitochondrial spare respiratory capacity in association with increased cell proliferation. Rapamycin decreased these responses, showing that mTORC1 signaling supports mitochondrial energy supply for cell proliferation, an important step in fibroblast trans-differentiation into myofibroblasts. Collectively, these results establish a key mechanistic role for mTORC1 activation in environmental Cd-dependent lung fibrosis.

NLRP3 deficiency improves bone healing of tooth extraction sockets through SMAD2/3-RUNX2-mediated osteoblast differentiation

Impaired bone healing following tooth extraction poses a significant challenge for implantation. As a crucial component of the natural immune system, the NLRP3 inflammasome is one of the most extensively studied pattern-recognition receptors, and is involved in multiple diseases. Yet, the role of NLRP3 in bone healing remains to be clarified. Here, to investigate the effect of NLRP3 on bone healing, we established a maxillary first molar extraction model in wild-type and NLRP3KO mice using minimally invasive techniques. We observed that NLRP3 was activated during the bone repair phase, and its depletion enhanced socket bone formation and osteoblast differentiation. Moreover, NLRP3 inflammasome activation was found to inhibit osteogenic differentiation in alveolar bone-derived mesenchymal stem cells (aBMSCs), an effect mitigated by NLRP3 deficiency. Mechanistically, we established that the SMAD2/3-RUNX2 signaling pathway is a downstream target of NLRP3 inflammasome activation, and SMAD2/3 knockdown partially reversed the significant decrease in expression of RUNX2, OSX, and ALP induced by NLRP3. Thus, our findings demonstrate that NLRP3 negatively modulates alveolar socket bone healing and contributes to the understanding of the NLRP3-induced signaling pathways involved in osteogenesis regulation.

RRM2 Regulates Hepatocellular Carcinoma Progression Through Activation of TGF-β/Smad Signaling and Hepatitis B Virus Transcription

BACKGROUND

Hepatocellular carcinoma (HCC) is a type of malignant tumor with high morbidity and mortality. Untimely treatment and high recurrence are currently the major challenges for HCC. The identification of potential targets of HCC progression is crucial for the development of new therapeutic strategies.

METHODS

Bioinformatics analyses have been employed to discover genes that are differentially expressed in clinical cases of HCC. A variety of pharmacological methods, such as MTT, colony formation, EdU, Western blotting, Q-PCR, wound healing, Transwell, cytoskeleton F-actin filaments, immunohistochemistry (IHC), hematoxylin-eosin (HE) staining, and dual-luciferase reporter assay analyses, were utilized to study the pharmacological effects and potential mechanisms of ribonucleotide reductase regulatory subunit M2 (RRM2) in HCC.

RESULTS

RRM2 expression is significantly elevated in HCC, which is well correlated with poor clinical outcomes. Both in vitro and in vivo experiments demonstrated that RRM2 promoted HCC cell growth and metastasis. Mechanistically, RRM2 modulates the EMT phenotype of HCC, and further studies have shown that RRM2 facilitates the activation of the TGF-β/Smad signaling pathway. SB431542, an inhibitor of TGF-β signaling, significantly inhibited RRM2-induced cell migration. Furthermore, RRM2 expression was correlated with diminished survival in HBV-associated HCC patients. RRM2 knockdown decreased the levels of HBV RNA, pgRNA, cccDNA, and HBV DNA in HepG2.2.15 cells exhibiting sustained HBV infection, while RRM2 knockdown inhibited the activity of the HBV Cp, Xp, and SpI promoters.

CONCLUSION

RRM2 is involved in the progression of HCC by activating the TGF-β/Smad signaling pathway. RRM2 increases HBV transcription in HBV-expressing HCC cells. Targeting RRM2 may be of potential value in the treatment of HCC.

Soluble TGF-β decoy receptor TGFBR3 exacerbates Alzheimer's disease pathology by modifying microglial function

Alzheimer's disease (AD) is a major cause of progressive dementia characterized by memory loss and progressive neurocognitive dysfunction. However, the molecular mechanisms are not fully understood. To elucidate the molecular mechanism contributing to AD, an integrated analytical workflow was deployed to identify pivotal regulatory target within the RNA-sequencing (RNA-seq) data of the temporal cortex from AD patients. Soluble transforming growth factor beta receptor 3 (sTGFBR3) was identified as a critical target in AD, which was abnormally elevated in AD patients and AD mouse models. We then demonstrated that sTGFBR3 deficiency restored spatial learning and memory deficits in amyloid precursor protein (APP)/PS1 and streptozotocin (STZ)-induced neuronal impairment mice after its expression was disrupted by a lentiviral (LV) vector expressing shRNA. Mechanistically, sTGFBR3 deficiency augments TGF-β signaling and suppressing the NF-κB pathway, thereby reduced the number of disease-associated microglia (DAMs), inhibited proinflammatory activity and increased the phagocytic activity of DAMs. Moreover, sTGFBR3 deficiency significantly mitigated acute neuroinflammation provoked by lipopolysaccharide (LPS) and alleviated neuronal dysfunction induced by STZ. Collectively, these results position sTGFBR3 as a promising candidate for therapeutic intervention in AD.

Targeted TGF-βR2 Silencing in the Retrotrapezoid Nucleus Mitigates Respiratory Dysfunction and Cognitive Decline in a Mouse Model of Cerebral Amyloid Angiopathy with and without Stroke

Cerebral amyloid angiopathy (CAA) is characterized by the deposition of amyloid-beta peptides within cerebral blood vessels, leading to neurovascular complications. Ischemic strokes result from acute disruptions in cerebral blood flow, triggering metabolic disturbances and neurodegeneration. Both conditions often co-occur and are associated with respiratory dysfunctions. The retrotrapezoid nucleus (RTN), which is crucial for CO2 sensing and breathing regulation in the brainstem, may play a key role in breathing disorders seen in these conditions. This study aims to investigate the role of Transforming Growth Factor Beta (TGF-β) signaling in the RTN on respiratory and cognitive functions in CAA, both with and without concurrent ischemic stroke. Adult male Tg-SwDI (CAA model) mice and C57BL/6 wild-type controls underwent stereotaxic injections of lentivirus targeting TGF-βR2 in the RTN. Stroke was induced by middle cerebral artery occlusion using a monofilament. Respiratory functions were assessed using whole-body plethysmography, while cognitive functions were evaluated through the Barnes Maze and Novel Object Recognition Test (NORT). Immunohistochemical analysis was conducted to measure TGF-βR2 and GFAP expressions in the RTN. CAA mice exhibited significant respiratory dysfunctions, including reduced respiratory rates and increased apnea frequency, as well as impaired cognitive performance. TGF-βR2 silencing in the RTN improved respiratory functions and cognitive outcomes in CAA mice. In CAA mice with concurrent stroke, TGF-βR2 silencing similarly enhanced respiratory and cognitive functions. Immunohistochemistry confirmed reduced TGF-βR2 and GFAP expressions in the RTN following silencing. Our findings demonstrate that increased TGF-β signaling and gliosis in the RTN contribute to respiratory and cognitive dysfunctions in CAA and CAA with stroke. Targeting TGF-βR2 signaling in the RTN offers a promising therapeutic strategy to mitigate these impairments. This study is the first to report a causal link between brainstem gliosis and both respiratory and cognitive dysfunctions in CAA and stroke models.

p21 regulates expression of ECM components and promotes pulmonary fibrosis via CDK4 and Rb

Fibrosis and accumulation of senescent cells are common tissue changes associated with aging. Here, we show that the CDK inhibitor p21 (CDKN1A), known to regulate the cell cycle and the viability of senescent cells, also controls the expression of extracellular matrix (ECM) components in senescent and proliferating cells of the fibrotic lung, in a manner dependent on CDK4 and Rb phosphorylation. p21 knockout protects mice from the induction of lung fibrosis. Moreover, inducible p21 silencing during fibrosis development alleviates disease pathology, decreasing the inflammatory response and ECM accumulation in the lung, and reducing the amount of senescent cells. Furthermore, p21 silencing limits fibrosis progression even when introduced during disease development. These findings show that one common mechanism regulates both cell cycle progression and expression of ECM components, and suggest that targeting p21 might be a new approach for treating age-related fibrotic pathologies.

An inducible sphingosine kinase 1 in hepatic stellate cells potentiates liver fibrosis

Hepatic stellate cells (HSCs) play a role in hepatic fibrosis and sphingosine kinase (SphK) is involved in biological processes. As studies on the regulatory mechanisms and functions of SphK in HSCs during liver fibrosis are currently limited, this study aimed to elucidate the regulatory mechanism and connected pathways of SphK upon HSC activation. The expression of SphK1 was higher in HSCs than in hepatocytes, and upregulated in activated primary HSCs. SphK1 was also increased in liver homogenates of carbon tetrachloride-treated or bile duct ligated mice and in transforming growth factor-β (TGF-β)-treated LX-2 cells. TGF-β-mediated SphK1 induction was due to Smad3 signaling in LX-2 cells. SphK1 modulation altered the expression of liver fibrogenesis-related genes. This SphK1-mediated profibrogenic effect was dependent on SphK1/sphingosine-1-phosphate/sphingosine-1-phosphate receptor signaling through ERK. Epigallocatechin gallate blocked TGF-β-induced SphK1 expression and hepatic fibrogenesis by attenuating Smad and MAPK activation. SphK1 induced by TGF-β facilitates HSC activation and liver fibrogenesis, which is reversed by epigallocatechin gallate. Accordingly, SphK1 and related signal transduction may be utilized to treat liver fibrosis.

TGF-β and RAS jointly unmask primed enhancers to drive metastasis

Epithelial-to-mesenchymal transitions (EMTs) and extracellular matrix (ECM) remodeling are distinct yet important processes during carcinoma invasion and metastasis. Transforming growth factor β (TGF-β) and RAS, signaling through SMAD and RAS-responsive element-binding protein 1 (RREB1), jointly trigger expression of EMT and fibrogenic factors as two discrete arms of a common transcriptional response in carcinoma cells. Here, we demonstrate that both arms come together to form a program for lung adenocarcinoma metastasis and identify chromatin determinants tying the expression of the constituent genes to TGF-β and RAS inputs. RREB1 localizes to H4K16acK20ac marks in histone H2A.Z-loaded nucleosomes at enhancers in the fibrogenic genes interleukin-11 (IL11), platelet-derived growth factor-B (PDGFB), and hyaluronan synthase 2 (HAS2), as well as the EMT transcription factor SNAI1, priming these enhancers for activation by a SMAD4-INO80 nucleosome remodeling complex in response to TGF-β. These regulatory properties segregate the fibrogenic EMT program from RAS-independent TGF-β gene responses and illuminate the operation and vulnerabilities of a bifunctional program that promotes metastatic outgrowth.

Landscape transcriptomic analysis of bovine follicular cells during key phases of ovarian follicular development

BACKGROUND

There are many gaps in our understanding of the mechanisms involved in ovarian follicular development in cattle, particularly regarding follicular deviation, acquisition of ovulatory capacity, and preovulatory changes. Molecular evaluations of ovarian follicular cells during follicular development in cattle, especially serial transcriptomic analyses across key growth phases, have not been reported. This study aims to address this gap by analyzing gene expression using RNA-seq in granulosa and antral cells recovered from ovarian follicular fluid during critical phases of ovarian follicular development in Holstein cows.

RESULTS

Integrated analysis of gene ontology (GO), gene set enrichment (GSEA), protein-protein interaction (PPI), and gene topology identified that differentially expressed genes (DEGs) in the largest ovarian follicles at deviation (Dev) were primarily involved in FSH-negative feedback, steroidogenesis, cell proliferation, apoptosis, and the prevention of early follicle rupture. In contrast, DEGs in the second largest follicles (DevF2) were mainly related to loss of cell viability, apoptosis, and immune cell invasion. In the dominant (PostDev) and preovulatory (PreOv) follicles, DEGs were associated with vascular changes and inflammatory responses.

CONCLUSIONS

The transcriptome of ovarian follicular fluid cells had a predominance of granulosa cells in the dominant follicle at deviation, with upregulation of genes involved in cell viability, steroidogenesis, and apoptosis prevention, whereas in the non-selected follicle there was upregulation of cell death-related transcripts. Immune cell transcripts increased significantly after deviation, particularly in preovulatory follicles, indicating strong intrafollicular chemotactic activity. We inferred that immune cell invasion occurred despite an intact basal lamina, contributing to follicular maturation.

SMAD3 mediates the specification of human induced pluripotent stem cell-derived epicardium into progenitors for the cardiac pericyte lineage

Understanding the molecular mechanisms of epicardial epithelial-to-mesenchymal transition (EMT), particularly in directing cell fate toward epicardial derivatives, is crucial for regenerative medicine using human induced pluripotent stem cell (iPSC)-derived epicardium. Although transforming growth factor β (TGF-β) plays a pivotal role in epicardial biology, orchestrating EMT during embryonic development via downstream signaling through SMAD proteins, the function of SMAD proteins in the epicardium in maintaining vascular homeostasis or mediating the differentiation of various epicardial-derived cells (EPDCs) is not yet well understood. Our study reveals that TGF-β-independent SMAD3 expression autonomously predicts epicardial cell specification and lineage maintenance, acting as a key mediator in promoting the angiogenic-oriented specification of the epicardium into cardiac pericyte progenitors. This finding uncovers a novel role for SMAD3 in the human epicardium, particularly in generating cardiac pericyte progenitors that enhance cardiac microvasculature angiogenesis. This insight opens new avenues for leveraging epicardial biology in developing more effective cardiac regeneration strategies.

Repulsive guidance molecules b (RGMb): molecular mechanism, function and role in diseases

Repulsive guidance molecule b (RGMb), a glycosylphosphatidylinositol-anchored member of the RGM family, is initially identified as a co-receptor of bone morphogenetic protein (BMP) in the nervous system. The expression of RGMb is transcriptionally regulated by dorsal root ganglion 11 (DRG11), which is a transcription factor expressed in embryonic DRG and dorsal horn neurons and plays an important role in the development of sensory circuits. RGMb is involved in important physiological processes such as embryonic development, immune response, intercellular adhesion and tumorigenesis. Furthermore, RGMb is mainly involved in the regulation of RGMb-neogenin-Rho and BMP signalling pathways. The recent discovery of programmed death-ligand 2 (PD-L2)-RGMb binding reveals that the cell signalling network and functional regulation centred on RGMb are extremely complex. The latest report suggests that down-regulation of the PD-L2-RGMb pathway in the gut microbiota promotes an anti-tumour immune response, which defines a potentially effective immune strategy. However, the biological function of RGMb in a variety of human diseases has not been fully determined, and will remain an active research field. This article reviews the properties and functions of RGMb, focusing on its role under various physiological and pathological conditions.

Small molecule agents against alopecia: Potential targets and related pathways

Alopecia has emerged as a global concern, extending beyond the middle-aged and elderly population and increasingly affecting younger individuals. Despite its growing prevalence, the treatment options and effective drugs for alopecia remain limited due to the incomplete understanding of its underlying mechanisms. Therefore, it is urgent to explore the pathogenesis of alopecia and discover novel and safer therapeutic agents. This review provided an overview of the prevailing clinical disorders of alopecia, and the key pathways and targets involved in hair growth process. Additionally, it discusses FDA-approved drugs and clinical candidates for the treatment of alopecia, and explores small molecule compounds with anti-alopecia potential in the drug discovery phase. These endeavors are expected to provide researchers with valuable scientific insights and practical information for anti-alopecia drug discovery.

ZNF8 Orchestrates with Smad3 to Promote Lung Metastasis by Recruiting SMYD3 in Breast Cancer

Most deaths in breast cancer patients are attributed to metastasis, and lung metastasis is associated with a particularly poor prognosis; therefore it is imperative to identify potential target for intervention. The transforming growth factor-β (TGF-β) pathway plays a vital role in breast cancer metastasis, in which Smad3 is the key mediator and performs specific functions by binding with different cofactors. However, Smad3 cofactors involved in lung metastasis have not yet been identified. This study first establishes the interactome of Smad3 in breast cancer cells and identifies ZNF8 as a novel Smad3 cofactor. Furthermore, the results reveal that ZNF8 is closely associated with breast cancer lung metastasis prognosis, and specifically facilitates TGF-β pathway-mediated breast cancer lung metastasis by participating in multiple processes. Mechanistically, ZNF8 binds with Smad3 to enhance the H3K4me3 modification and promote the expression of lung metastasis signature genes by recruiting SMYD3. SMYD3 inhibition by BCI121 effectively prevents ZNF8-mediated lung metastasis. Overall, the study identifies a novel cofactor of TGF-β/Smad3 that promotes lung metastasis in breast cancer and introduces potential therapeutic strategies for the early management of breast cancer lung metastasis.

Terminal α1,2-fucosylation of glycosphingolipids by FUT1 is a key regulator in early cell-fate decisions

The embryonic cell surface is rich in glycosphingolipids (GSLs), which change during differentiation. The reasons for GSL subgroup variation during early embryogenesis remain elusive. By combining genomic approaches, flow cytometry, confocal imaging, and transcriptomic data analysis, we discovered that α1,2-fucosylated GSLs control the differentiation of human pluripotent cells (hPCs) into germ layer tissues. Overexpression of α1,2-fucosylated GSLs disrupts hPC differentiation into mesodermal lineage and reduces differentiation into cardiomyocytes. Conversely, reducing α1,2-fucosylated groups promotes hPC differentiation and mesoderm commitment in response to external signals. We find that bone morphogenetic protein 4 (BMP4), a mesodermal gene inducer, suppresses α1,2-fucosylated GSL expression. Overexpression of α1,2-fucosylated GSLs impairs SMAD activation despite BMP4 presence, suggesting α-fucosyl end groups as BMP pathway regulators. Additionally, the absence of α1,2-fucosylated GSLs in early/late mesoderm and primitive streak stages in mouse embryos aligns with the hPC results. Thus, α1,2-fucosylated GSLs may regulate early cell-fate decisions and embryo development by modulating cell signaling.

Knockouts of CYP51A1, DHCR24, or SC5D from cholesterol synthesis reveal pathways modulated by sterol intermediates

Sterols from cholesterol synthesis are crucial for cholesterol production, but also have individual roles difficult to assess in vivo due to essentiality of cholesterol. We developed HepG2 cell models with knockouts (KOs) for three enzymes of cholesterol synthesis, each accumulating specific sterols. Surprisingly, KOs of CYP51, DHCR24, and SC5D shared only 9% of differentially expressed genes. The most striking was the phenotype of CYP51 KO with highly elevated lanosterol and 24,25-dihydrolanosterol, significant increase in G2+M phase and enhanced cancer and cell cycle pathways. Comparisons with mouse liver Cyp51 KO data suggest 24,25-dihydrolanosterol activates similar cell proliferation pathways, possibly via elevated LEF1 and WNT/NFKB signaling. In contrast, SC5D and DHCR24 KO cells with elevated lathosterol or desmosterol proliferated slowly, with downregulated E2F, mitosis, and enriched HNF1A. These findings demonstrate that increase of lanosterol and 24,25-dihydrolanosterol, but not other sterols, promotes cell proliferation in hepatocytes.

Relationship of Signaling Pathways between RKIP Expression and the Inhibition of EMT-Inducing Transcription Factors SNAIL1/2, TWIST1/2 and ZEB1/2

Untreated primary carcinomas often lead to progression, invasion and metastasis, a process that involves the epithelial-to-mesenchymal transition (EMT). Several transcription factors (TFs) mediate the development of EMT, including SNAIL1/SNAIL2, TWIST1/TWIST2 and ZEB1/ZEB2, which are overexpressed in various carcinomas along with the under expression of the metastasis suppressor Raf Kinase Inhibitor Protein (RKIP). Overexpression of RKIP inhibits EMT and the above associated TFs. We, therefore, hypothesized that there are inhibitory cross-talk signaling pathways between RKIP and these TFs. Accordingly, we analyzed the various properties and biomarkers associated with the epithelial and mesenchymal tissues and the various molecular signaling pathways that trigger the EMT phenotype such as the TGF-β, the RTK and the Wnt pathways. We also presented the various functions and the transcriptional, post-transcriptional and epigenetic regulations for the expression of each of the EMT TFs. Likewise, we describe the transcriptional, post-transcriptional and epigenetic regulations of RKIP expression. Various signaling pathways mediated by RKIP, including the Raf/MEK/ERK pathway, inhibit the TFs associated with EMT and the stabilization of epithelial E-Cadherin expression. The inverse relationship between RKIP and the TF expressions and the cross-talks were further analyzed by bioinformatic analysis. High mRNA levels of RKIP correlated negatively with those of SNAIL1, SNAIL2, TWIST1, TWIST2, ZEB1, and ZEB2 in several but not all carcinomas. However, in these carcinomas, high levels of RKIP were associated with good prognosis, whereas high levels of the above transcription factors were associated with poor prognosis. Based on the inverse relationship between RKIP and EMT TFs, it is postulated that the expression level of RKIP in various carcinomas is clinically relevant as both a prognostic and diagnostic biomarker. In addition, targeting RKIP induction by agonists, gene therapy and immunotherapy will result not only in the inhibition of EMT and metastases in carcinomas, but also in the inhibition of tumor growth and reversal of resistance to various therapeutic strategies. However, such targeting strategies must be better investigated as a result of tumor heterogeneities and inherent resistance and should be better adapted as personalized medicine.

Optimal performance objectives in the highly conserved bone morphogenetic protein signaling pathway

Throughout development, complex networks of cell signaling pathways drive cellular decision-making across different tissues and contexts. The transforming growth factor β (TGF-β) pathways, including the BMP/Smad pathway, play crucial roles in determining cellular responses. However, as the Smad pathway is used reiteratively throughout the life cycle of all animals, its systems-level behavior varies from one context to another, despite the pathway connectivity remaining nearly constant. For instance, some cellular systems require a rapid response, while others require high noise filtering. In this paper, we examine how the BMP-Smad pathway balances trade-offs among three such systems-level behaviors, or "Performance Objectives (POs)": response speed, noise amplification, and the sensitivity of pathway output to receptor input. Using a Smad pathway model fit to human cell data, we show that varying non-conserved parameters (NCPs) such as protein concentrations, the Smad pathway can be tuned to emphasize any of the three POs and that the concentration of nuclear phosphatase has the greatest effect on tuning the POs. However, due to competition among the POs, the pathway cannot simultaneously optimize all three, but at best must balance trade-offs among the POs. We applied the multi-objective optimization concept of the Pareto Front, a widely used concept in economics to identify optimal trade-offs among various requirements. We show that the BMP pathway efficiently balances competing POs across species and is largely Pareto optimal. Our findings reveal that varying the concentration of NCPs allows the Smad signaling pathway to generate a diverse range of POs. This insight identifies how signaling pathways can be optimally tuned for each context.

SMAD4 mutations causing Myhre syndrome are under positive selection in the male germline

While it is widely thought that de novo mutations (DNMs) occur randomly, we previously showed that some DNMs are enriched because they are positively selected in the testes of aging men. These "selfish" mutations cause disorders with a shared presentation of features, including exclusive paternal origin, significant increase of the father's age, and high apparent germline mutation rate. To date, all known selfish mutations cluster within the components of the RTK-RAS-MAPK signaling pathway, a critical modulator of testicular homeostasis. Here, we demonstrate the selfish nature of the SMAD4 DNMs causing Myhre syndrome (MYHRS). By analyzing 16 informative trios, we show that MYHRS-causing DNMs originated on the paternally derived allele in all cases. We document a statistically significant epidemiological paternal age effect of 6.3 years excess for fathers of MYHRS probands. We developed an ultra-sensitive assay to quantify spontaneous MYHRS-causing SMAD4 variants in sperm and show that pathogenic variants at codon 500 are found at elevated level in sperm of most men and exhibit a strong positive correlation with donor's age, indicative of a high apparent germline mutation rate. Finally, we performed in vitro assays to validate the peculiar functional behavior of the clonally selected DNMs and explored the basis of the pathophysiology of the different SMAD4 sperm-enriched variants. Taken together, these data provide compelling evidence that SMAD4, a gene operating outside the canonical RAS-MAPK signaling pathway, is associated with selfish spermatogonial selection and raises the possibility that other genes/pathways are under positive selection in the aging human testis.

TGFβ in Pancreas and Colorectal Cancer: Opportunities to Overcome Therapeutic Resistance

TGFβ is a pleiotropic signaling pathway that plays a pivotal role in regulating a multitude of cellular functions. TGFβ has a dual role in cell regulation where it induces growth inhibition and cell death; however, it can switch to a growth-promoting state under cancerous conditions. TGFβ is upregulated in colorectal cancer and pancreatic cancer, altering the tumor microenvironment and immune system and promoting a mesenchymal state. The upregulation of TGFβ in certain cancers leads to resistance to immunotherapy, and attempts to inhibit TGFβ expression have led to reduced therapeutic resistance when combined with chemotherapy and immunotherapy. Here, we review the current TGFβ inhibitor drugs in clinical trials for pancreatic and colorectal cancer, with the goal of uncovering advances in improving clinical efficacy for TGFβ combinational treatments in patients. Furthermore, we discuss the relevance of alterations in TGFβ signaling and germline variants in the context of personalizing treatment for patients who show lack of response to current therapeutics.

Hypoxic Regulation of the KLK4 Gene in two Different Prostate Cancer Cells Treated with TGF- β

The human kallikrein-related peptidase (KLK) family which consists of 15 members is associated with prostate cancer and other cancers. It has been reported that overexpression of KLK4 in prostate cancer correlates with bone metastasis or advanced stage. Hypoxia occurs in the early stages of prostate cancer due to the accumulation of acidic metabolites or reactive oxygen species (ROS). In our study, KLK4 gene expression in hypoxic conditions in PC-3 and LNCaP cells which are treated with TGF-β was evaluated with mRNA, protein, and promoter activity levels. A chemical hypoxia model was created and confirmed at mRNA and protein level. No statistically significant cytotoxic effect of CoCl2 and TGF-β was observed in PC-3 and LNCaP cells with the MTT test. Four different truncated KLK4 gene promoter constructs were cloned in pmetLuc expression vector and basal activities of all promoter fragments were analyzed. The activities of P1 (-447/ + 657), P2 (-103/ + 657), and P3 (-267/ + 657) promoter fragments increased in hypoxic conditions except P4 (+555/ + 657), which does not contain the SMAD and HRE region. KLK4 mRNA levels in both PC-3 and LNCaP cells increased in the hypoxia and hypoxia/TGF groups compared to the non-treated groups. The stimulating effect of TGF-β is correlated with the increase in SMAD2/3 mRNA levels. KLK4 expression is up-regulated by TGF-β, especially under hypoxic conditions, and its interaction with the SMAD pathway is determined with different inhibitor experiments. HIF-1α and SMAD transcription factors bind to the KLK4 promoter showing the direct interaction of HIF-1α (-80/-52) and SMAD (+163/+194) regions with EMSA.

MicroRNA-455-3P as a peripheral biomarker and therapeutic target for mild cognitive impairment and Alzheimer's disease

MicroRNAs are small non-coding RNAs evolutionary conserved molecules. They regulate cellular processes, including RNA silencing, post-translational gene expression and neurodegeneration. MicroRNAs are involved with human diseases such as cancer, Alzheimer's disease (AD) and others. Interestingly, cerebrospinal fluids (CSF) and the blood of AD patients have altered expressions of many RNAs, which may serve as potential peripheral biomarkers. The intensive investigation from our lab revealed that microRNA-455-3 P (miR-455-3p) is a strong candidate as a potential biomarker and therapeutic target for AD. Several genes implicated in the pathogenesis of AD are directly targeted by miR-455-3p. Several years of our lab research revealed that miR-455-3p regulates important physiological processes associated with AD, such as the processing of the amyloid precursor protein (APP), TGF-β signaling, the regulation of oxidative stress, mitochondrial biogenesis, and synaptic damages. The expression of miR-455-3p in mild cognitive impaired subjects and AD patients pointed out its involvement in AD progression. Recently, our lab generated both transgenic and knockout mice for miR-455-3p. Interestingly miR-455-3p transgenic mice showed superior cognitive learning, improved memory and extended lifespan compared to age matched wild-type mice, whereas miR-455-3-p knockout mice showed cognitive decline and reduced lifespan. Information derived from mouse models further demonstrated the advantageous impact of miR-455-3p on dendritic growth, synaptogenesis, and mitochondrial biogenesis in preventing the onset and progression of AD. The identification of miR-455-3p as a biomarker was suggested by its presence in postmortem AD brains, B-lymphocytes, and fibroblasts. Our hypothesis that miR-455-3p could be a peripheral biomarker and therapeutic target for AD.

Structure, unique biological properties, and mechanisms of action of transforming growth factor β

Transforming growth factor β (TGF-β) is a ubiquitous molecule that is extremely conserved structurally and plays a systemic role in human organism. TGF-β is a homodimeric molecule consisting of two subunits joined through a disulphide bond. In mammals, three genes code for TGF-β1, TGF-β2, and TGF-β3 isoforms of this cytokine with a dominating expression of TGF-β1. Virtually, all normal cells contain TGF-β and its specific receptors. Considering the exceptional role of fine balance played by the TGF-β in anumber of physiological and pathological processes in human body, this cytokine may be proposed for use in medicine as an immunosuppressant in transplantology, wound healing and bone repair. TGFb itself is an important target in oncology. Strategies for blocking members of TGF-β signaling pathway as therapeutic targets have been considered. In this review, signalling mechanisms of TGF-β1 action are addressed, and their role in physiology and pathology with main focus on carcinogenesis are described.

Loss of TGFβ-Mediated Repression of Angiopoietin-2 in Pericytes Underlies Germinal Matrix Hemorrhage Pathogenesis

BACKGROUND

TGF (transforming growth factor)-β pathway is central to blood-brain barrier development as it regulates cross talk between pericytes and endothelial cells. Murine embryos lacking TGFβ receptor Alk5 (activin receptor-like kinase 5) in brain pericytes (mutants) display endothelial cell hyperproliferation, abnormal vessel morphology, and gross germinal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH), leading to perinatal lethality. Mechanisms underlying how ALK5 signaling in pericytes noncell autonomously regulates endothelial cell behavior remain elusive.

METHODS

Transcriptomic analysis of human brain pericytes with ALK5 silencing identified differential gene expression. Brain vascular cells isolated from mutant embryonic mice with GMH-IVH and preterm human IVH brain samples were utilized for target validation. Finally, pharmacological and genetic inhibition was used to study the therapeutic effects on GMH-IVH pathology.

RESULTS

Herein, we establish that the TGFβ/ALK5 pathway robustly represses ANGPT2 (angiopoietin-2) in pericytes via epigenetic remodeling. TGFβ-driven SMAD (suppressor of mothers against decapentaplegic) 3/4 associates with TGIF1 (TGFβ-induced factor homeobox 1) and HDAC (histone deacetylase) 5 to form a corepressor complex at the Angpt2 promoter, resulting in promoter deacetylation and gene repression. Moreover, murine and human germinal matrix vessels display increased ANGPT2 expression during GMH-IVH. Isolation of vascular cells from murine germinal matrix identifies pericytes as a cellular source of excessive ANGPT2. In addition, mutant endothelial cells exhibit higher phosphorylated TIE2 (tyrosine protein kinase receptor). Pharmacological or genetic inhibition of ANGPT2 in mutants improves germinal matrix vessel morphology and attenuates GMH pathogenesis. Importantly, genetic ablation of Angpt2 in mutant pericytes prevents perinatal lethality, prolonging survival.

CONCLUSIONS

This study demonstrates that TGFβ-mediated ANGPT2 repression in pericytes is critical for maintaining blood-brain barrier integrity and identifies pericyte-derived ANGPT2 as an important pathological target for GMH-IVH.

Targeted dephosphorylation of SMAD3 as an approach to impede TGF-β signaling

TGF-β (transforming growth factor-β) signaling is involved in a myriad of cellular processes and its dysregulation has been implicated in many human diseases, including fibrosis and cancer. TGF-β transcriptional responses are controlled by tail phosphorylation of transcription factors SMAD2 and SMAD3 (mothers against decapentaplegic homolog 2/3). Therefore, targeted dephosphorylation of phospho-SMAD3 could provide an innovative mechanism to block some TGF-β-induced transcriptional responses, such as the transcription of SERPINE-1, which encodes plasminogen activator inhibitor 1 (PAI-1). Here, by developing and employing a bifunctional molecule, BDPIC (bromoTAG-dTAG proximity-inducing chimera), we redirected multiple phosphatases, tagged with bromoTAG, to dephosphorylate phospho-SMAD3, tagged with dTAG. Using CRISPR-Cas9 technology, we generated homozygous double knock-in A549 bromoTAG/bromoTAG PPM1H/ dTAG/dTAG SMAD3 cells, in which the BDPIC-induced proximity between bromoTAG-PPM1H and dTAG-SMAD3 led to a robust dephosphorylation of dTAG-SMAD3 and a significant decrease in SERPINE-1 transcription. Our work demonstrates targeted dephosphorylation of phospho-proteins as an exciting modality for rewiring cell signaling.

Analysis of the DNA-binding properties of TGF-β-activated Smad complexes unveils a possible molecular basis for cellular context-dependent signaling

Transforming growth factor-β (TGF-β) is a pleiotropic cytokine that modulates a wide variety of cellular responses by regulating target gene expression. It principally transmits signals via receptor-activated transcription factors Smad2 and Smad3, which form trimeric complexes with Smad4 upon activation and regulate gene expression by binding to genomic DNA. Here, we examined the mechanisms by which TGF-β regulates the transcription of target genes in a cell context-dependent manner by screening a double-stranded DNA oligonucleotide library for DNA sequences bound to endogenous activated Smad complexes. Screening was performed by cyclic amplification of selected targets (CASTing) using an anti-Smad2/3 antibody and nuclear extracts isolated from three cell lines (A549, HepG2, and HaCaT) stimulated with TGF-β. The preference of the activated Smad complexes for conventional Smad-binding motifs such as Smad-binding element (SBE) and CAGA motifs was different in HepG2 than in the other two cell lines, which may indicate the distinct composition of the activated Smad complexes. Several transcription factor-binding motifs other than SBE or CAGA, including the Fos/Jun-binding motifs, were detected in the enriched sequences. Reporter assays using sequences containing these transcription factor-binding motifs together with Smad-binding motifs indicated that some of the motifs may be involved in cell type-dependent transcriptional activation by TGF-β. The results suggest that the CASTing method is useful for elucidating the molecular basis of context-dependent Smad signaling.

Using microRNAs Networks to Understand Pancreatic Cancer-A Literature Review

Pancreatic cancer is a severe disease, challenging to diagnose and treat, and thereby characterized by a poor prognosis and a high mortality rate. Pancreatic ductal adenocarcinoma (PDAC) represents approximately 90% of pancreatic cancer cases, while other cases include neuroendocrine carcinoma. Despite the growing knowledge of the pathophysiology of this cancer, the mortality rate caused by it has not been effectively reduced. Recently, microRNAs have aroused great interest among scientists and clinicians, as they are negative regulators of gene expression, which participate in many processes, including those related to the development of pancreatic cancer. The aim of this review is to show how microRNAs (miRNAs) affect key signaling pathways and related cellular processes in pancreatic cancer development, progression, diagnosis and treatment. We included the results of in vitro studies, animal model of pancreatic cancer and those performed on blood, saliva and tumor tissue isolated from patients suffering from PDAC. Our investigation identified numerous dysregulated miRNAs involved in KRAS, JAK/STAT, PI3/AKT, Wnt/β-catenin and TGF-β signaling pathways participating in cell cycle control, proliferation, differentiation, apoptosis and metastasis. Moreover, some miRNAs (miRNA-23a, miRNA-24, miRNA-29c, miRNA-216a) seem to be engaged in a crosstalk between signaling pathways. Evidence concerning the utility of microRNAs in the diagnosis and therapy of this cancer is poor. Therefore, despite growing knowledge of the involvement of miRNAs in several processes associated with pancreatic cancer, we are beginning to recognize and understand their role and usefulness in clinical practice.