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Introduction and objectives Long non-coding RNAs (lncRNAs) have great potential as therapeutic targets in hepatocellular carcinoma (HCC). In this study, we aimed to uncover the function and molecular mechanism of long intergenic non-protein coding RNA 1006 (LINC01006) in HCC. Materials and methods Mice were injected with HCC cells in order to establish the HCC model. Quantitative reverse transcription polymerase chain reaction was used to determine the expression levels of LINC01006, cell adhesion molecule 1 (CADM1), and microRNA (miR)-194-5p in HCC tissues and cells. The cell proliferation, invasion, and migration abilities were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide, transwell, and wound healing assays. The interrelation between LINC01006, miR-194-5p, and CADM1 was confirmed by a dual-luciferase reporter assay. Western blotting was employed to assess the relative protein expression level of CADM1. Results LINC01006 and CADM1 displayed upregulation, but miR-194-5p exhibited downregulation in HCC cells and tissues. Short hairpin (sh)-LINC01006 and miR-194-5p mimics repressed the proliferative, migratory, and invasive capacities of HCC cells, and injection of sh-LINC01006 restrained the growth of HCC tumours in mice. LINC01006 served as a competing endogenous RNA of miR-194-5p and was inversely correlated with miR-194-5p. CADM1 was targeted by miR-194-5p, inversely correlated with miR-194-5p, and positively associated with LINC01006. Furthermore, transfection of pcDNA-CADM1 or the miR-194-5p inhibitor reversed the suppressive effects of sh-LINC01006 on the proliferation, invasion, and migration abilities of HCC cells. Conclusions Downregulation of LINC01006 repressed the development of HCC by sponging miR-194-5p to modulate the expression of CADM1, implying its potential as a therapeutic target for HCC.

The zebrafish kidney has been used effectively for studying kidney development, repair and disease. New gene editing capability makes it a more versatile in vivo vertebrate model system to investigate renal epithelial cells in their native environment. In this chapter we focus on dissecting gene function in basic cellular biology of renal epithelial cells, including lumen formation and cell polarity, in intact zebrafish embryos.

The kidneys are a crucial pair of organs that are responsible for filtering the blood to remove waste, maintain electrolyte and water homeostasis, and regulate blood pressure. There are a number of factors, both genetic and environmental, that can impair the function of the kidneys resulting in significant morbidity and mortality for millions of people affected by kidney disease worldwide. The zebrafish, Danio rerio, has emerged as an attractive vertebrate model in the study of kidney development and disease and has proven to be a powerful tool in the advancement of how kidney development occurs in vertebrates and how the kidney repairs itself after injury. Zebrafish share significant similarities in kidney development and composition of nephrons, the functional unit of the kidney. This makes the zebrafish a very promising model to study the mechanisms by which renal developmental defects occur. Furthermore, zebrafish are ideally suited for the study of how vertebrate kidneys respond to injury and have provided researchers with invaluable information on repair processes after kidney injury. Importantly, zebrafish have profound potential for discovering treatment modalities and, in fact, studies in zebrafish models have provided leads for therapeutics for human patients suffering from kidney disease and kidney injury. Here, we discuss the similarities and differences in zebrafish and mammalian kidney models, and highlight some of the major contributions the zebrafish has made in the understanding of kidney development and disease.

The target-of-rapamycin (TOR) pathway is a major regulator of cellular growth, division, and metabolism by coupling growth and nutrient cues to fundamental processes such as translation and transcription. In vertebrate models, disruptions affecting components of the TOR pathway result in cilia size abnormalities and ciliopathic phenotypes such as renal cysts. However, the mechanism by which the TOR pathway influenced cilia length and function was unknown. Recent work from zebrafish, in conjunction with the green alga Chlamydomonas, demonstrates that TOR complex 1 (TORC1)-mediated cilia length control is achieved through translational regulation of ciliary precursors. Further, in zebrafish, aberrant TORC1 signaling leads to left-right asymmetric patterning defects due to inefficient ciliary motility and fluid flow generation in the Kupffer's vesicle, a conserved embryonic organ that establishes laterality. Together, such findings show the utility of a combinatorial zebrafish and Chlamydomonas approach to dissecting the mechanistic relationship between the cilium and signaling molecules such as TOR. Here, we describe tools, reagents, and methodologies for the manipulation of the TOR pathway and the analysis of cilia morphology and function in zebrafish and Chlamydomonas.

The cilium, a previously little studied cell surface protrusion, has emerged as an important organelle in vertebrate cells. This tiny structure is essential for normal embryonic development, including the formation of left-right asymmetry, limb morphogenesis, and the differentiation of sensory cells. In the adult, cilia also function in a variety of processes, such as the survival of photoreceptor cells, and the homeostasis in several tissues, including the epithelia of nephric ducts. Human ciliary malfunction is associated with situs inversus, kidney cysts, polydactyly, blindness, mental retardation, obesity, and many other abnormalities. The genetic accessibility and optical transparency of the zebrafish make it an excellent vertebrate model system to study cilia biology. In this chapter, we describe the morphology and distribution of cilia in zebrafish embryonic and larval organs. We also provide essential protocols to analyze cilia formation and function.