Novel roles for LIX1L in promoting cancer cell proliferation through ROS1-mediated LIX1L phosphorylation

A-to-I edited miR-154-p13-5p inhibited cell proliferation and migration and induced apoptosis by targeting LIX1L in the bladder cancer

With the advancement of RNA sequencing technology, there has been a drive to uncover and elucidate the pivotal role of A-to-I RNA editing events in tumorigenesis. However, A-to-I miRNA editing events have been clearly identified in bladder cancer, the molecular mechanisms underlying their role in bladder cancer remain unclear. In our investigation, we observed a notable under-expression of edited miR-154-p13-5p in bladder cancer (BC) tissues, in contrast to normal counterparts. Remarkably, heightened expression levels of edited miR-154-p13-5p correlated with improved survival outcomes. To assess the impact of modified miR-154-p13-5p, we conducted a string of cell phenotype assays through transfection of the corresponding miRNAs or siRNAs. The results unequivocally demonstrate that edited miR-154-p13-5p exerts a substantial inhibitory influence on proliferation, migration, and induces apoptosis by specifically targeting LIX1L in bladder cancer. Moreover, we observed that the editing of miR-154-p13-5p or LIX1L-siRNAs inhibits the expression of LIX1L, thereby suppressing EMT-related proteins and cell cycle protein CDK2. Simultaneously, an upregulation in the expression levels of Caspase-3 and Cleaved Caspase-3 were also detected. Our research findings suggest that the upregulation of edited miR-154-p13-5p could potentially enhance the prognosis of bladder cancer, thereby presenting molecular biology-based therapeutic strategies.

Immunolocalization of lix1 in the regenerating tail of lizard indicates that the protein is mainly present in the nervous tissue

PURPOSE

Lizard regeneration derives from the re-activation of a number of developmental genes after tail amputation. Among genes with the highest expression, as indicated from the transcriptome, is lix1 which functional role is not known.

METHOD

An antibody that cross-reacts with the lizard Podarcis muralis lix1 has been utilized to detect by immunofluorescence the sites of localization of the protein in the regenerating tail.

RESULTS

Lix1-protein is almost exclusively localized in the regenerating spinal cord (ependyma) and nerves growing into the blastema, in sparse blastema cells but is undetectable in other tissues.

CONCLUSIONS

Since the spinal cord is essential to stimulate tail regeneration it is hypothesized that the lix1 protein is part of the signaling or growing factors produced from the regenerating spinal cord that are needed for tail regeneration of the lizard tail.

DCHS1, Lix1L, and the Septin Cytoskeleton: Molecular and Developmental Etiology of Mitral Valve Prolapse

Mitral valve prolapse (MVP) is a common cardiac valve disease that often progresses to serious secondary complications requiring surgery. MVP manifests as extracellular matrix disorganization and biomechanically incompetent tissues in the adult setting. However, MVP has recently been shown to have a developmental basis, as multiple causal genes expressed during embryonic development have been identified. Disease phenotypes have been observed in mouse models with human MVP mutations as early as birth. This study focuses on the developmental function of DCHS1, one of the first genes to be shown as causal in multiple families with non-syndromic MVP. By using various biochemical techniques as well as mouse and cell culture models, we demonstrate a unique link between DCHS1-based cell adhesions and the septin-actin cytoskeleton through interactions with cytoplasmic protein Lix1-Like (LIX1L). This DCHS1-LIX1L-SEPT9 axis interacts with and promotes filamentous actin organization to direct cell-ECM alignment and valve tissue shape.

Limb expression 1-like (LIX1L) protein promotes cholestatic liver injury by regulating bile acid metabolism

BACKGROUND & AIMS

Cholestatic liver diseases comprise a variety of disorders of bile formation and/or flow which generally result in progressive hepatobiliary injury. Regulation of bile acid (BA) synthesis and homeostasis is a promising strategy for the treatment of cholestatic liver disease. Limb expression 1-like protein (LIX1L) plays an important role in post-transcriptional gene regulation, yet its role in cholestatic liver injury remains unclear.

METHODS

LIX1L expression was studied in patients with primary sclerosing cholangitis (PSC) or primary biliary cholangitis (PBC), and 3 murine models of cholestasis (bile duct ligation [BDL], Mdr2 knockout [Mdr2^-/-], and cholic acid [CA] feeding). Lix1l knockout mice were employed to investigate the function of LIX1L in cholestatic liver diseases. Chromatin immunoprecipitation assays were performed to determine whether Egr-1 bound to the Lix1l promoter. MiRNA expression profiling was analyzed by microarray. An adeno-associated virus (AAV)-mediated hepatic delivery system was used to identify the function of miR-191-3p in vivo.

RESULTS

LIX1L expression was increased in the livers of patients with PSC and PBC, and in the 3 murine models, as well as in BA-stimulated primary mouse hepatocytes. BA-induced Lix1l upregulation was dependent on Egr-1, which served as a transcriptional activator. LIX1L deficiency attenuated cholestatic liver injury in BDL and Mdr2^-/- mice. MiR-191-3p was the most reduced miRNA in livers of WT-BDL mice, while it was restored in Lix1l^-/--BDL mice. MiR-191-3p targets and downregulates Lrh-1, thereby inhibiting Cyp7a1 and Cyp8b1 expression. AAV-mediated hepatic delivery of miR-191-3p significantly attenuated cholestatic liver injury in Mdr2^-/- mice.

CONCLUSIONS

LIX1L deficiency alleviates cholestatic liver injury by inhibiting BA synthesis. LIX1L functions as a nexus linking BA/Egr-1 and miR-191-3p/LRH-1 signaling. LIX1L and miR-191-3p may be promising targets for the treatment of BA-associated hepatobiliary diseases.

LAY SUMMARY

Bile acid homeostasis can be impaired in cholestatic liver diseases. Our study identified a novel mechanism of positive feedback regulation in cholestasis. LIX1L and miR-191-3p represent potential therapeutic targets for cholestatic liver diseases.

LIX1-like protein promotes liver cancer progression via miR-21-3p-mediated inhibition of fructose-1,6-bisphosphatase

Limb and CNS expressed 1 like (LIX1L) is over-expressed in several types of tumors. However, the function of LIX1L in glucose metabolism and hepatocellular carcinoma (HCC) progression remains elusive. Here we report that LIX1L is over-expressed in human HCC tissues, which predicts unfavorable prognosis. LIX1L deficiency in vivo significantly attenuated liver cancer initiation in mice. Functional studies indicated that LIX1L overexpression elevated proliferation, migratory, invasive capacities of HCC cells in vitro, and promoted liver cancer growth and metastasis in vivo. LIX1L knockdown up-regulated fructose-1,6-bisphosphatase (FBP1) expression to reduce glucose consumption as well as lactate production. Mechanistically, LIX1L increased miR-21-3p expression, which targeted and suppressed FBP1, thereby promoting HCC growth and metastasis. MiR-21-3p inhibitor could abrogate LIX1L induced enhancement of cell migration, invasion, and glucose metabolism. Inhibition of miR-21-3p suppressed tumor growth in an orthotopic tumor model. Our results establish LIX1L as a critical driver of hepatocarcinogenesis and HCC progression, with implications for prognosis and treatment.

G protein-coupled estrogen receptor 1 (GPER-1) and agonist G-1 inhibit growth of ovarian cancer cells by activation of anti-tumoral transcriptome responses: impact of GPER-1 mRNA on survival

PURPOSE

The present study intended to further elucidate the role of G protein-coupled estrogen receptor 1 (GPER-1) in ovarian cancer by comparing the effects of a GPER-1 knockdown and treatment with its agonist G-1 on cell growth, apoptosis, and the transcriptome of two ovarian cancer cell lines. Furthermore, the role of GPER-1 in ovarian cancer survival was examined.

METHODS

GPER-1 expression in OVCAR-3 and OAW-42 ovarian cancer cells was knocked down by RNAi. The effects on cell growth were measured by means of the fluorimetric cell titer blue assay and on the transcriptome by Affymetrix GeneChip analysis. The effect of GPER-1 on patient's survival was examined using open source mRNA and clinical data of 1657 ovarian cancer patients.

RESULTS

GPER-1 knockdown resulted in a significant growth stimulation of both cell lines, whereas treatment with agonist G-1 decreased growth of both cell lines in a dose-dependent manner. Transcriptome analyses revealed a set of 18 genes being conversely regulated after GPER-1 knockdown and G-1 treatment. Generally, treatment with G-1 led to a transcriptome response associated with growth inhibition. In contrast, knockdown of GPER-1 exerted opposite effects, stimulating pathways activating mitosis, but inhibiting pathways associated with apoptosis or interferon signaling. Further analyses using open-access mRNA and clinical data by bioinformatical online tools revealed a longer OS (HR = 0.86, p = 0.057) and PFS (HR = 0.81, p = 0.0035) of ovarian cancer patients with high GPER-1 mRNA expression.

CONCLUSIONS

The results of this study clearly support the hypothesis that GPER-1 acts as a tumor suppressor in ovarian cancer.

Identification of urinary exosomal noncoding RNAs as novel biomarkers in chronic kidney disease

In chronic kidney disease (CKD), the decline in the glomerular filtration rate is associated with increased morbidity and mortality and thus poses a major challenge for healthcare systems. While the contribution of tissue-derived miRNAs and mRNAs to CKD progression has been extensively studied, little is known about the role of urinary exosomes and their association with CKD. Exosomes are small, membrane-derived endocytic vesicles that contribute to cell-to-cell communication and are present in various body fluids, such as blood or urine. Next-generation sequencing approaches have revealed that exosomes are enriched in noncoding RNAs and thus exhibit great potential for sensitive nucleic acid biomarkers in various human diseases. Therefore, in this study we aimed to identify urinary exosomal ncRNAs as novel biomarkers for diagnosis of CKD. Since up to now most approaches have focused on the class of miRNAs, we extended our analysis to several other noncoding RNA classes, such as tRNAs, tRNA fragments (tRFs), mitochondrial tRNAs, or lincRNAs. For their computational identification from RNA-seq data, we developed a novel computational pipeline, designated as ncRNASeqScan. By these analyses, in CKD patients we identified 30 differentially expressed ncRNAs, derived from urinary exosomes, as suitable biomarkers for early diagnosis. Thereby, miRNA-181a appeared as the most robust and stable potential biomarker, being significantly decreased by about 200-fold in exosomes of CKD patients compared to healthy controls. Using a cell culture system for CKD indicated that urinary exosomes might indeed originate from renal proximal tubular epithelial cells.