Temporal and Spatial Post-Transcriptional Regulation of Zebrafish tie1 mRNA by Long Noncoding RNA During Brain Vascular Assembly

Abstract

Objective Tyrosine kinase containing immunoglobulin and epidermal growth factor homology1 (Tie1), an endothelial and hematopoietic cell-specific receptor tyrosine kinase, is an important regulator of angiogenesis and critical for maintaining vascular integrity. The post-transcriptional regulation of tie1 mRNA expression is not understood, but it might partly explain Tie1’s differential expression pattern in endothelium. Following up on our previous work that identified natural antisense transcripts from the tie1 locus—tie1 antisense (tie1AS), which regulates tie1 mRNA levels in zebrafish—we attempted to identify the mechanism of this regulation. Approach and Results Through in vitro and in vivo ribonucleoprotein binding studies, we demonstrated that tie1AS lncRNA interacts with an RNA binding protein—embryonic lethal and abnormal vision Drosophila-like1 (Elavl1)—that regulates tie1 mRNA levels. When we disrupted the interaction between tie1AS and Elavl1 by using constitutively active anti-sense morpholino oligonucleotides (MOs) or photoactivatable MOs, tie1 mRNA levels increased between 26 and 31 hours post fertilization (hpf), particularly in the head. This increase correlated with dilation of primordial midbrain channels, smaller eyes, and reduced ventricular space. We also observed these phenotypes when we used CRISPRi to knock down tie1AS. Treatment of the MO-injected embryos with a small molecule that decreased tie1 mRNA levels rescued all three abnormal phenotypes. Conclusions We identified a novel mode of temporal and spatial post-transcriptional regulation of tie1 mRNA. It involves lncRNA, tie1AS, and Elavl1 (an interactor of tie1AS).

Lessons learned from a lncRNA odyssey for two genes with vascular functions, DLL4 and TIE1

“…We found that tielAS selectively binds tie1 mRNA in the cytoplasm and that overexpression of tielAS downregulates tie1 mRNA levels, causing defects in endothelial cell contacts that result in abnormal intersomitic vessel formation in the zebrafish trunk [11]. Our recent work elucidates the mechanism [23]. Using several novel technologies, which will be discussed later in this review, we demonstrated that zebrafish tielAS lncRNA forms a complex with embryonic lethal and abnormal vision Drosophila-like 1 (Elavl1, an RNA-binding protein) to regulate tie1 mRNA levels in specific tissues in the head across a small window of time [23].…”

“…Our recent work elucidates the mechanism [23]. Using several novel technologies, which will be discussed later in this review, we demonstrated that zebrafish tielAS lncRNA forms a complex with embryonic lethal and abnormal vision Drosophila-like 1 (Elavl1, an RNA-binding protein) to regulate tie1 mRNA levels in specific tissues in the head across a small window of time [23]. Thus, zebrafish tielAS post-transcriptionally regulates tie1 mRNA in a temporal and spatial manner (Figure 2).…”

Knockdown of Novel lncRNA TCONS_00028652 in Zebrafish Affects Embryonic Vasculature Development

“…Recently, several developmentrelated lncRNAs have been identified and characterized in zebrafish and mouse (Dinger et al 2008;Pauli et al 2015;Luo et al 2016) and the results suggest that lncRNAs can substantially affect gene regulation during embryogenesis. For instance, lncRNA tie-AS was found to be involved in transcriptional regulation of vascular development (Li et al 2009;Chowdhury et al 2018). LncRNA braveheart was required for cardiovascular lineage commitment and activated the cardiac vascular gene network (Klattenhoff et al 2013;Hou et al 2017).…”

Expression and Gene Regulatory Network of SNHG1 in Hepatocellular Carcinoma

“…Long noncoding RNAs (lncRNAs) are an important category of ncRNAs that have lengths longer than 200 nucleotides [7,8]. Recent studies have revealed that lncRNAs perform various functions in biological processes, such as cell differentiation [9], signal transduction [10] or posttranscriptional regulation [11], that are conducive to the progression of tumours and many other diseases [12]. Increasing evidence suggests that lncRNAs can work alone or in cooperation with microRNAs (miRNAs).…”