Effect of decreased expression of latent TGF-ß binding proteins 4 on the pathogenesis of emphysema as an age-related disease.

PURPOSE: Latent TGF-ß binding protein 4 (LTBP4) is involved in the production of elastin fibers and has been implicated in LTBP4-related cutis laxa and its complication, emphysema-like changes. Various factors have been implicated in the pathogenesis of emphysema, including elastic degeneration, inflammation, cellular senescence, mitochondrial dysfunction, and decreased angiogenesis in the lungs. We investigated the association between LTBP4 and emphysema using human lung fibroblasts with silenced LTBP4 genes. METHODS: Cell contraction, elastin expression, cellular senescence, inflammation, anti-inflammatory factors, and mitochondrial function were compared between the LTBP4 small interfering RNA (siRNA) and control siRNA. RESULTS: Under the suppression of LTBP4, significant changes were observed in the following: decreased cell contractility, decreased elastin expression, increased expression of the p16 gene involved in cellular senescence, increased TNFα, decreased GSTM3 and SOD, decreased mitochondrial membrane potential, and decreased VEGF expression. Furthermore, the decreased cell contractility and increased GSTM3 expression observed under LTBP4 suppression were restored by the addition of N-acetyl-L-cysteine or recombinant LTBP4. CONCLUSION: The decreased elastin expression, cellular senescence, inflammation, decreased antioxidant activity, mitochondrial dysfunction, and decreased VEGF expression under reduced LTBP4 expression may all be involved in the destruction of the alveolar wall in emphysema. Smoking is the most common cause of emphysema; however, genetic factors related to LTBP4 expression and other factors may also contribute to its pathogenesis.

Epigenetic identification of LTBP4 as a putative tumor suppressor in breast cancer.

Aim: To explore the LTBP4's expression, prognostic significance and molecular mechanism of action in breast cancer (BC).Methods: On the basis of omics datasets and experiments, we conducted a synthetical analysis of LTBP4 in BC.Results & conclusion: LTBP4 was downregulated in BC with high promoter methylation and low genetic alteration. DNA methylation was negatively associated with LTBP4 mRNA expression. Higher LTBP4 associated with better survival. LTBP4 was enrichment in extracellular matrix receptor interactions, cell adhesion molecules, cell cycle and MAPK pathway. LTBP4 expression and methylation were positively and negatively associated with tumor infiltrating immune cells, respectively. In conclusion, LTBP4 is a putative tumor suppressor in BC, which expression is regulated by DNA methylation and relates with prognosis.

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Novel indel variation of LTBP4 gene associates with risk of sudden cardiac death in Chinese populations with coronary artery disease.

The objective of this study is to investigate whether common genetic variants of the LTBP4 gene are linked to the susceptibility of sudden cardiac death in individuals who have atherosclerotic coronary artery disease (SCD-CAD) in Chinese populations. A total of 208 SCD-CAD cases and 638 controls were included in the analysis, and logistic regression was employed to assess the association between a 4-bp insertion/deletion polymorphism (rs34005443) within LTBP4 and the susceptibility to SCD-CAD among Chinese individuals. Logistic regression analysis demonstrated a notable association between the insertion allele of rs34005443 and an escalated susceptibility to SCD-CAD [odds ratio (OR) = 1.434; 95 % confidence interval:1.14-1.80; P = 1.79 × 10-3]. Genotype-phenotype correlation analysis was performed using Genotype-Tissue expression (GTEx) database and further validated by human myocardium using qPCR. Correlation analysis revealed that LTBP4 expression level was lower in samples with the insertion allele. Furthermore, the dual-luciferase activity assays indicated that rs34005443 may play a regulatory role. Additionally, we predicted 30 transcription factors that are likely to bind to rs34005443 and its highly linked genetic variants via 3DSNP database. Subsequent GO and KEGG analysis indicated that these transcription factors have a significant function in regulating gene expression. Finally, PPI network analysis suggested a tight connection between LTBP4 proteins and TGFßs, highlighting these genes as potential hub genes in the context of SCD-CAD. In summary, our study revealed that rs34005443 might contribute to SCD-CAD susceptibility by regulating LTBP4 expression. These findings revealed that this indel could be a potentially functional marker for molecular diagnosis and risk stratification of SCD-CAD.

The IAAM LTBP4 Haplotype is Protective Against Dystrophin-Deficient Cardiomyopathy.

Background: Dilated cardiomyopathy (DCM) is a major complication of, and leading cause of mortality in Duchenne muscular dystrophy (DMD). Its severity, age at onset, and rate of progression display wide variability, whose molecular bases have been scarcely elucidated. Potential DCM-modifying factors include glucocorticoid (GC) and cardiological treatments, DMD mutation type and location, and variants in other genes. Methods and Results: We retrospectively collected 3138 echocardiographic measurements of left ventricular ejection fraction (EF), shortening fraction (SF), and end-diastolic volume (EDV) from 819 DMD participants, 541 from an Italian multicentric cohort and 278 from the Cooperative International Neuromuscular Group Duchenne Natural History Study (CINRG-DNHS). Using generalized estimating equation (GEE) models, we estimated the yearly rate of decrease of EF (-0.80%) and SF (-0.41%), while EDV increase was not significantly associated with age. Utilizing a multivariate generalized estimating equation (GEE) model we observed that mutations preserving the expression of the C-terminal Dp71 isoform of dystrophin were correlated with decreased EDV (-11.01 mL/m2, p = 0.03) while for dp116 were correlated with decreased EF (-4.14%, p = <0.001). The rs10880 genotype in the LTBP4 gene, previously shown to prolong ambulation, was also associated with increased EF and decreased EDV (+3.29%, p = 0.002, and -10.62 mL/m2, p = 0.008) with a recessive model. Conclusions: We quantitatively describe the progression of systolic dysfunction progression in DMD, confirm the effect of distal dystrophin isoform expression on the dystrophin-deficient heart, and identify a strong effect of LTBP4 genotype of DCM in DMD.

Latent transforming growth factor beta binding protein 4: A regulator of mitochondrial function in acute kidney injury.

Recently, latent transforming growth factor beta binding protein 4 (LTBP4) was implicated in the pathogenesis of renal damage through its modulation of mitochondrial dynamics. The seminal article written by Su et al. entitled "LTBP4 (Latent Transforming Growth Factor Beta Binding Protein 4) Protects Against Renal Fibrosis via Mitochondrial and Vascular Impacts" uncovers LTBP4's renoprotective role against acute kidney injury via modulating mitochondrial dynamics. Recently, LTBP4 has emerged as a driver in the mitochondrial-dependent modulation of age-related organ pathologies. This article aims to expand our understanding of LTBP4's diverse roles in these diseases in the context of these recent findings.

Specific Overexpression of YAP in Vascular Smooth Muscle Attenuated Abdominal Aortic Aneurysm Formation by Activating Elastic Fiber Assembly via LTBP4.

Abdominal aortic aneurysm (AAA) is a fatal vascular disease. Vascular smooth muscle cells (VSMCs) play a crucial role in the pathogenesis of AAA. Increasing evidence has shown that Yes-associated protein (YAP) is involved in diverse vascular diseases. However, the role of YAP in AAA remains unclear. The current study aimed to determine the role of YAP in AAA formation and the underlying mechanism. We found that YAP expression in VSMCs was markedly decreased in human and experimental AAA samples. Furthermore, VSMC-specific YAP overexpression prevented several pathogenic factor-induced AAA. Mechanistically, YAP overexpression in VSMCs promoted latent transforming growth factor-ß binding protein 4 (LTBP4) expression, an important factor in elastic fiber assembly. Finally, silencing of LTBP4 in VSMCs abolished the protective role of YAP in AAA formation in vivo. Our results suggest that YAP promotes LTBP4-mediated elastic fibril assembly in VSMCs, which mitigates elastin degradation and AAA formation.

Association of polymorphisms rs2303729, rs10880, and rs1131620 of LTBP4 with sarcopenia in elderly patients with type 2 diabetes mellitus.

BACKGROUND: Latent TGFß binding protein 4 (LTBP4) modifies skeletal muscle function, and polymorphisms in this gene have been associated with a longer ambulation time in patients with Duchenne muscular dystrophy. However, no studies associate these polymorphisms with an acquired muscle condition. AIM: The study aims to determine whether three functional variants within the LTBP4 were associated with sarcopenia in patients with type 2 diabetes mellitus (T2DM). SUBJECTS AND METHODS: We performed an analysis with 144 elderly individuals with T2DM, including 101 without sarcopenia and 43 with sarcopenia. Polymorphism frequency was determined by real-time PCR allelic discrimination TaqMan assay. RESULTS: Under different genetic models, the univariant analysis did not show a significant association of any polymorphism with sarcopenia. But the multivariate model analysis showed that variant rs1131620 (OR 7.852, 95% CI 1.854-33.257, p = 0.005) was significantly associated with sarcopenia under a dominant model. Under the same analysis, the variants rs2303729 and rs10880 had a more discrete association (OR 3.537 95% CI 1.078-11.607, p = 0.037; OR 5.008, 95% CI 1.120-22.399, p = 0.035, respectively). CONCLUSIONS: Our study highlights the importance of studying LTBP4 polymorphisms associated with sarcopenia. These findings suggest that the rs1131620 polymorphism of the LTBP4 may be part of the observed sarcopenia process in patients with T2DM.

LTBP4, SPP1, and CD40 Variants: Genetic Modifiers of Duchenne Muscular Dystrophy Analyzed in Serbian Patients.

BACKGROUND: Clinical course variability in Duchenne muscular dystrophy (DMD) is partially explained by the mutation location in the DMD gene and variants in modifier genes. We assessed the effect of the SPP1, CD40, and LTBP4 genes and DMD mutation location on loss of ambulation (LoA). METHODS: SNPs in SPP1-rs28357094, LTBP4-rs2303729, rs1131620, rs1051303, rs10880, and CD40-rs1883832 were genotyped, and their effect was assessed by survival and hierarchical cluster analysis. RESULTS: Patients on glucocorticoid corticosteroid (GC) therapy experienced LoA one year later (p = 0.04). The modifying effect of SPP1 and CD40 variants, as well as LTBP4 haplotypes, was not observed using a log-rank test and multivariant Cox regression analysis. Cluster analysis revealed two subgroups with statistical trends in differences in age at LoA. Almost all patients in the cluster with later LoA had the protective IAAM LTBP4 haplotype and statistically significantly fewer CD40 genotypes with harmful T allele and "distal" DMD mutations. CONCLUSIONS: The modifying effect of SPP1, CD40, and LTBP4 was not replicated in Serbian patients, although our cohort was comparable in terms of its DMD mutation type distribution, SNP allele frequencies, and GC-positive effect with other European cohorts. Cluster analysis may be able to identify patient subgroups carrying a combination of the genetic variants that modify LoA.

First report of a short in-frame biallelic deletion removing part of the EGF-like domain calcium-binding motif in LTBP4 and causing autosomal recessive cutis laxa type 1C.

Cutis laxa (CL) is a rare connective tissue disorder characterized by wrinkled, abundant and sagging skin, sometimes associated with systemic impairment. Biallelic alterations in latent transforming growth factor beta-binding protein 4 gene (LTBP4) cause autosomal recessive type 1C cutis laxa (ARCL1C, MIM #613177). The present report describes the case of a 17-months-old girl with cutis laxa together with a literature review of previous ARCL1C cases. Based on proband main clinical signs (cutis laxa and pulmonary emphysema), clinical exome sequencing (CES) was performed and showed a new nine base-pairs homozygous in-frame deletion in LTBP4 gene. RT-PCR and cDNA Sanger sequencing were performed in order to clarify its impact on RNA. This report demonstrates that a genetic alteration in the EGF-like 14 domain calcium-binding motif of LTBP4 gene is likely responsible for cutis laxa in our patient.

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 TGFß 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.

Autosomal recessive cutis laxa type 1C with a homozygous LTBP4 splicing variant: a case report and update of literature.

BACKGROUND: Autosomal recessive cutis laxa (ARCL) is a heterogeneous disorder with three primary forms (ARCL 1, ARCL 2 and ARCL 3). Latent transforming growth factor beta binding protein 4 (LTBP4) anomalies cause ARCL1C and are connected to different problems in the skin and other organs. Herein, we present a seven month old Iranian boy with a clinical manifestation of ARCL1 with literature review of previous cases with attributes of ARCL1C. METHODS: Considering the craniofacial characteristics and respiratory distress of the proband, cutis laxa (CL) was expected and whole-exome sequencing (WES) was performed. RESULTS: In the proband, signs of CL were mainly located in the face, thorax, and abdomen. The prenatal investigation revealed a diaphragmatic hernia and certain uncommon signs, such as an atrial septal defect and pyloric stenosis. The WES showed a novel homozygous mutation (c.533-1G > A) in exon six of the LTBP4 gene. CONCLUSION: This report showed a new variant with uncommon clinical features, such as a stenosis atrial septal defect and pyloric stenosis, which causes ARCL1C. Unfortunately, the proband developed several heart problems and died at the age of seven months and seven days. Thus, a more in-depth evaluation is needed to clarify the different aspects of CL related to LTBP4 disorder.

Aberrant interaction between mutated ADAMTSL2 and LTBP4 is associated with adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) is a complex spinal deformity with a prevalence of 1%-3%. Genetic factors have been associated with the etiology of AIS. However, previous studies mainly focused on common single nucleotide polymorphisms which confer modest disease risk. Recently, rare variants in FBN1 and other extracellular matrix genes have been implicated in AIS, suggesting a potential overlapping disease etiology between AIS and hereditary connective tissue disorders (HCTD). In this study, we systematically analyzed rare variants in a set of HCTD-related genes in 302 AIS patients who underwent exome sequencing. We firstly focused on pathogenic variants based on a monogenic inheritance and identified nine disease-associated variants in FBN1, COL11A1, COL11A2 and TGFBR2. We then explored the potential interactions between variants in different genes based on the case-control statistics. We identified three ADAMTSL2-LTBP4 variant pairs in three AIS patients and none in controls. Furthermore, we revealed that the variant pairs identified in these genes could affect the interaction between ADAMTSL2 and LTBP4 and upregulate TGF-ß signaling pathway in human fibroblasts. Our findings implicate that the aberrant interaction between mutated ADAMTSL2 and LTBP4 was associated with AIS.

Clinical and Molecular Delineation of Cutis Laxa Syndromes: Paradigms for Homeostasis.

Cutis laxa (CL) syndromes are a large and heterogeneous group of rare connective tissue disorders that share loose redundant skin as a hallmark clinical feature, which reflects dermal elastic fiber fragmentation. Both acquired and congenital-Mendelian- forms exist. Acquired forms are progressive and often preceded by inflammatory triggers in the skin, but may show systemic elastolysis. Mendelian forms are often pleiotropic in nature and classified upon systemic manifestations and mode of inheritance. Though impaired elastogenesis is a common denominator in all Mendelian forms of CL, the underlying gene defects are diverse and affect structural components of the elastic fiber or impair metabolic pathways interfering with cellular trafficking, proline synthesis, or mitochondrial functioning. In this chapter we provide a detailed overview of the clinical and molecular characteristics of the different cutis laxa types and review the latest insights on elastic fiber assembly and homeostasis from both human and animal studies.

Genetic Modifiers and Phenotype of Duchenne Muscular Dystrophy: A Systematic Review and Meta-Analysis.

The transforming growth factor beta (TGFß) pathway could modulate the Duchenne muscular dystrophy (DMD) phenotype. This meta-analysis aims to estimate the association of genetic variants involved in the TGFß pathway, including the latent transforming growth factor beta binding protein 4 (LTBP4) and secreted phosphoprotein 1 (SPP1) genes, among others, with age of loss of ambulation (LoA) and cardiac function in patients with DMD. Meta-analyses were conducted for the hazard ratio (HR) of LoA for each genetic variant. A subgroup analysis was performed in patients treated exclusively with glucocorticoids. Eight studies were included in the systematic review and four in the meta-analyses. The systematic review suggests a protective effect of LTBP4 haplotype IAAM (recessive model) for LoA. It is also suggested that the SPP1 rs28357094 genotype G (dominant model) is associated with early LoA in glucocorticoids-treated patients. The meta-analysis of the LTBP4 haplotype IAAM showed a protective association with LoA, with an HR = 0.78 (95% CI: 0.67-0.90). No association with LoA was observed for the SPP1 rs28357094. The LTBP4 haplotype IAAM is associated with a later LoA, especially in the Caucasian population, while the SPP1 rs28357094 genotype G could be associated with a poor response to glucocorticoids. Future research is suggested for SPP1 rs11730582, LTBP4 rs710160, and THBS1 rs2725797.

ZNF326 promotes colorectal cancer epithelial-mesenchymal transition.

Zinc-finger protein 326 (ZNF326) activity has been reported in different tumors, but its expression and possible mechanism of action in colorectal cancer are not known. In this study, we applied immunohistochemistry to detect the expression of ZNF326 in colorectal tissues. Next, we used a ZNF326 expression plasmid and small interfering (si) RNA-ZNF326 (siZNF326) to transfect colorectal cancer cell lines in order to determine the effect of ZNF326 on cell migration and as well as its potential role in promoting epithelial-mesenchymal transition (EMT). A higher ZNF326 expression in the nuclei of colorectal tumor cells compared to normal mucosa was observed (70.3%, 109/155 specimens vs. 23.2%, 36/155 specimens). A high ZNF326 expression level was positively correlated with tumor differentiation, tumor-node-metastasis (TNM) staging, and lymph node metastasis. Transfection of cancer cell lines (SW480 and SW620) with a ZNF326-overexpression vector promoted colorectal cancer cell invasion and altered the expression of EMT-related proteins. Vimentin, N-cadherin, Snail, and Slug were upregulated, whereas E-cadherin and zonula occludens-1 (ZO-1) were downregulated. In contrast, downregulation of ZNF326 expression using siRNA-ZNF326 in cancer cell lines (CL187 and RKO) resulted in the opposite findings. ZNF326 overexpression also upregulated the expression of latent transforming growth factor beta binding protein 4 (LTBP4) and p-Smad2/3. In conclusion, ZNF326 promoted the EMT and invasiveness of colorectal cancer cells. These findings are likely due to LTBP4 and p-Smad2/3 upregulation and, in turn, transforming growth factor beta (TGF-ß) signaling activation.

The pan HDAC inhibitor Givinostat improves muscle function and histological parameters in two Duchenne muscular dystrophy murine models expressing different haplotypes of the LTBP4 gene.

BACKGROUND: In the search of genetic determinants of Duchenne muscular dystrophy (DMD) severity, LTBP4, a member of the latent TGF-ß binding protein family, emerged as an important predictor of functional outcome trajectories in mice and humans. Nonsynonymous single-nucleotide polymorphisms in LTBP4 gene associate with prolonged ambulation in DMD patients, whereas an in-frame insertion polymorphism in the mouse LTBP4 locus modulates disease severity in mice by altering proteolytic stability of the Ltbp4 protein and release of transforming growth factor-ß (TGF-ß). Givinostat, a pan-histone deacetylase inhibitor currently in phase III clinical trials for DMD treatment, significantly reduces fibrosis in muscle tissue and promotes the increase of the cross-sectional area (CSA) of muscles in mdx mice. In this study, we investigated the activity of Givinostat in mdx and in D2.B10 mice, two mouse models expressing different Ltbp4 variants and developing mild or more severe disease as a function of Ltbp4 polymorphism. METHODS: Givinostat and steroids were administrated for 15 weeks in both DMD murine models and their efficacy was evaluated by grip strength and run to exhaustion functional tests. Histological examinations of skeletal muscles were also performed to assess the percentage of fibrotic area and CSA increase. RESULTS: Givinostat treatment increased maximal normalized strength to levels that were comparable to those of healthy mice in both DMD models. The effect of Givinostat in both grip strength and exhaustion tests was dose-dependent in both strains, and in D2.B10 mice, Givinostat outperformed steroids at its highest dose. The in vivo treatment with Givinostat was effective in improving muscle morphology in both mdx and D2.B10 mice by reducing fibrosis. CONCLUSION: Our study provides evidence that Givinostat has a significant effect in ameliorating both muscle function and histological parameters in mdx and D2.B10 murine models suggesting a potential benefit also for patients with a poor prognosis LTBP4 genotype.

LTBP4 in Health and Disease.

Latent transforming growth factor ß (TGFß)-binding protein (LTBP) 4, a member of the LTBP family, shows structural homology with fibrillins. Both these protein types are characterized by calcium-binding epidermal growth factor-like repeats interspersed with 8-cysteine domains. Based on its domain composition and distribution, LTBP4 is thought to adopt an extended structure, facilitating the linear deposition of tropoelastin onto microfibrils. In humans, mutations in LTBP4 result in autosomal recessive cutis laxa type 1C, characterized by redundant skin, pulmonary emphysema, and valvular heart disease. LTBP4 is an essential regulator of TGFß signaling and is related to development, immunity, injury repair, and diseases, playing a central role in regulating inflammation, fibrosis, and cancer progression. In this review, we focus on medical disorders or diseases that may be manipulated by LTBP4 in order to enhance the understanding of this protein.

Disruption of LTBP4 Inhibition-Induced TGFß1 Activation Promoted Cell Proliferation and Metastasis in Skin Melanoma by Inhibiting the Activation of the Hippo-YAP1 Signaling Pathway.

Melanoma is a malignant tumor derived from melanocytes, which is the most fatal skin cancer. The present study aimed to explore and elucidate the candidate genes in melanoma and its underlying molecular mechanism. A total of 1,156 differentially expressed genes were obtained from the GSE46517 dataset of Gene Expression Omnibus database using the package "limma" in R. Based on two algorithms (LASSO and SVM-RFE), we obtained three candidate DEGs (LTBP4, CDHR1, and MARCKSL1). Among them, LTBP4 was identified as a diagnostic marker of melanoma (AUC = 0.985). Down-regulation of LTBP4 expression was identified in melanoma tissues and cells, which predicted poor prognosis of patients with melanoma. Cox analysis results discovered that LTBP4 with low expression was an independent prognostic factor for overall survival in patients with melanoma. LTBP4 inhibition reduced cell apoptosis and promoted cell proliferation and metastasis. These changes were correlated with the expression levels of caspase-3, Ki67 and E-cadherin. Further, as indicated by tumor formation study of nude mice, LTBP4 silencing improved the tumorigenic ability of melanoma cells. Knockdown of LTBP4 increased the percentage of active TGFß1 secreted by melanoma cells. CTGF, Gyr61, and Birc5 expression levels were reduced, YAP1 phosphorylation was inhibited, and YAP1 was translocated from the cytoplasm to the nucleus in melanoma cells treated with TGF-ß1. These effects were reversed by LTBP4 overexpression. As evidenced by immunofluorescent staining, Western blotting and luciferase reporter assay, LTBP4 overexpression activated the Hippo signaling pathway, which was characterized by the increased nuclear-cytoplasmic translocation of YAP1 and the enhanced phosphorylation of YAP1, MST1, and MOB1. In addition, the effects of LTBP4 overexpression on inhibiting CTGF, Cyr61 and Birc5 expression, promoting the apoptosis, and inhibiting the metastasis and proliferation of melanoma cells were reversed by the overexpression of YAP1 or MST1. In conclusion, the LTBP4-TGFß1-Hippo-YAP1 axis is a critical pathway for the progression of skin melanoma.

Two novel compound heterozygous variants of LTBP4 in a Chinese infant with cutis laxa type IC and a review of the related literature.

BACKGROUND: Autosomal recessive cutis laxa type IC (ARCL IC, MIM: #613177) results from a mutation in the LTBP4 gene (MIM: #604710) on chromosome 19q13. CASE PRESENTATION: A 28-day-old Chinese infant with generalized cutis laxa accompanied by impaired pulmonary, gastrointestinal, genitourinary, retinal hemorrhage, abnormality of coagulation and hyperbilirubinemia was admitted to our hospital. To find out the possible causes of these symptoms, whole-exome sequencing was performed on the infant. Two novel pathogenic frame-shift variants [c.605_606delGT (p.Ser204fs * 8) and c.1719delC (p.Arg574fs * 199)] of the LTBP4 gene associated with ARCL IC were found which was later verified by Sanger sequencing. The pathogenicity of mutations was subsequently assessed by several software programs and databases. In addition, an analytical review on the clinical phenotypes of the disease previously reported in literature was performed. CONCLUSIONS: This is the first report of a Chinese infant with ARCL IC in China due to novel pathogenic variations of LTBP4. Our study extends the cutis laxa type IC mutation spectrum as well as the phenotypes associated with the disease in different populations.

Disruption of LTBP4 Induced Activated TGFß1, Immunosuppression Signal and Promoted Pulmonary Metastasis in Hepatocellular Carcinoma.

INTRODUCTION: The current prognosis of hepatocellular carcinoma (HCC) is unsatisfactory due to high rates of recurrence and metastasis, which has led to research focused on the discovery of metastasis genes. METHODS: In this study, we combined in silico analysis and in vitro transwell experiments to identify a metastasis gene. Then, we used an in vivo experiment to validate the metastasis. Furthermore, a series of experiments such as FACS, Western blot, and ELISA were applied to explore the function of the metastasis gene. RESULTS: LTBP4 (latent transforming growth factor beta binding protein 4) was confirmed as a metastasis gene, whose expression levels are correlated with the overall survival rate of HCC patients. We further showed that the knockout of LTBP4 in an HCC cell line increased cell proliferation, activated the cell cycle, and induced metastasis events. Moreover, we proved that LTBP4-KO could increase the percentage of active TGFß1 secreted by HCC cell lines, as well as the recruitment of MDSCs (myeloid-derived suppressor cells) by active TGFß1 (transforming growth factor beta 1), which further inhibited CD8+ T cell proliferation and activated the immune suppression signal. CONCLUSION: Our results demonstrate that the LTBP4-TGFß1-MDSCs axis is a critical pathway for the immune suppression signals of HCC primary tumors.