Small hairpin inhibitory RNA delivery in the metanephric organ culture identifies long noncoding RNA Pvt1 as a modulator of cyst growth

Activation of Piezo1 Inhibits Kidney Cystogenesis

The disruption of calcium signaling associated with polycystin deficiency has been proposed as the primary event underlying the increased abnormally patterned epithelial cell growth characteristic of Polycystic Kidney Disease. Calcium can be regulated through mechanotransduction, and the mechanosensitive cation channel Piezo1 has been implicated in sensing of intrarenal pressure and in urinary osmoregulation. However, a possible role for PIEZO1 in kidney cystogenesis remains undefined. We hypothesized that cystogenesis in ADPKD reflects altered mechanotransduction, suggesting activation of mechanosensitive cation channels as a therapeutic strategy for ADPKD. Here, we show that Yoda-1 activation of PIEZO1 increases intracellular Ca 2+ and reduces forskolin-induced cAMP levels in mIMCD3 cells. Yoda-1 reduced forskolin-induced IMCD cyst surface area in vitro and in mouse metanephros ex vivo in a dose-dependent manner. Knockout of polycystin-2 dampened the efficacy of PIEZO1 activation in reducing both cAMP levels and cyst surface area in IMCD3 cells. However, collecting duct-specific Piezo1 knockout neither induced cystogenesis in wild-type mice nor affected cystogenesis in the Pkd1 RC/RC model of ADPKD. Our study suggests that polycystin-2 and PIEZO1 play a role in mechanotransduction during cystogenesis in vitro , and ex vivo , but that in vivo cyst expansion may require inactivation or repression of additional suppressors of cystogenesis and/or growth. Our study provides a preliminary proof of concept for PIEZO1 activation as a possible component of combination chemotherapy to retard or halt cystogenesis and/or cyst growth.

Ablation of Long Noncoding RNA Hoxb3os Exacerbates Cystogenesis in Mouse Polycystic Kidney Disease

SIGNIFICANCE STATEMENT

Long noncoding RNAs (lncRNAs) are a class of nonprotein coding RNAs with pivotal functions in development and disease. They have emerged as an exciting new drug target category for many common conditions. However, the role of lncRNAs in autosomal dominant polycystic kidney disease (ADPKD) has been understudied. This study provides evidence implicating a lncRNA in the pathogenesis of ADPKD. We report that Hoxb3os is downregulated in ADPKD and regulates mammalian target of rapamycin (mTOR)/Akt pathway in the in vivo mouse kidney. Ablating the expression of Hoxb3os in mouse polycystic kidney disease (PKD) activated mTOR complex 2 (mTORC2) signaling and exacerbated the cystic phenotype. The results from our study provide genetic proof of concept for future studies that focus on targeting lncRNAs as a treatment option in PKD.

BACKGROUND

ADPKD is a monogenic disorder characterized by the formation of kidney cysts and is primarily caused by mutations in two genes, PKD1 and PKD2 .

METHODS

In this study, we investigated the role of lncRNA Hoxb3os in ADPKD by ablating its expression in the mouse.

RESULTS

Hoxb3os -null mice were viable and had grossly normal kidney morphology but displayed activation of mTOR/Akt signaling and subsequent increase in kidney cell proliferation. To determine the role of Hoxb3os in cystogenesis, we crossed the Hoxb3os -null mouse to two orthologous Pkd1 mouse models: Pkhd1/Cre; Pkd1F/F (rapid cyst progression) and Pkd1RC/RC (slow cyst progression). Ablation of Hoxb3os exacerbated cyst growth in both models. To gain insight into the mechanism whereby Hoxb3os inhibition promotes cystogenesis, we performed western blot analysis of mTOR/Akt pathway between Pkd1 single-knockout and Pkd1 - Hoxb3os double-knockout (DKO) mice. Compared with single-knockout, DKO mice presented with enhanced levels of total and phosphorylated Rictor. This was accompanied by increased phosphorylation of Akt at Ser 473 , a known mTORC2 effector site. Physiologically, kidneys from DKO mice displayed between 50% and 60% increase in cell proliferation and cyst number.

CONCLUSIONS

The results from this study indicate that ablation of Hoxb3os in mouse PKD exacerbates cystogenesis and dysregulates mTORC2.

Long Noncoding RNAs in the Pathogenesis of Insulin Resistance

Insulin resistance (IR), designated as the blunted response of insulin target tissues to physiological level of insulin, plays crucial roles in the development and progression of diabetes, nonalcoholic fatty liver disease (NAFLD) and other diseases. So far, the distinct mechanism(s) of IR still needs further exploration. Long non-coding RNA (lncRNA) is a class of non-protein coding RNA molecules with a length greater than 200 nucleotides. LncRNAs are widely involved in many biological processes including cell differentiation, proliferation, apoptosis and metabolism. More recently, there has been increasing evidence that lncRNAs participated in the pathogenesis of IR, and the dysregulated lncRNA profile played important roles in the pathogenesis of metabolic diseases including obesity, diabetes and NAFLD. For example, the lncRNAs MEG3, H19, MALAT1, GAS5, lncSHGL and several other lncRNAs have been shown to regulate insulin signaling and glucose/lipid metabolism in various tissues. In this review, we briefly introduced the general features of lncRNA and the methods for lncRNA research, and then summarized and discussed the recent advances on the roles and mechanisms of lncRNAs in IR, particularly focused on liver, skeletal muscle and adipose tissues.

Expression profile of long non-coding RNA in inner Mongolian cashmere goat with putative roles in hair follicles development

The hair follicle is a complex skin accessory organ, which determines hair growth. Long non-coding RNAs (lncRNAs) have been proven to play an important role in hair follicle development, but their specific mechanism is still unclear. In this study, high-throughput sequencing was used to obtain the expression profiles of lncRNA in the hair follicles of Inner Mongolian cashmere goats at different embryonic stages (45, 55, 65, and 75 days), and a total of 6,630 lncRNA were identified. According to the rules of hair follicle development, we combined miRNA and mRNA databases (published) and predicted lncRNA-miRNA, miRNA-mRNA, and lncRNA-mRNA interaction pairs in the 45 vs. 75 comparison group. We obtained 516 lncRNA-mRNA, 1,011 lncRNA-miRNA, and 7,411 miRNA-mRNA relationship pairs. Finally, target genes were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), and it was found that they were mainly enriched in the Wnt signaling pathway and PI3K-Akt signaling pathway related to hair follicle development, indicating that lncRNA may interact with miRNA/mRNA to directly or indirectly regulate the expression of genes related to hair follicle development. Dual-luciferase reporter gene analysis showed that lncRNA MSTRG.1705.1 could bind to Chi-miR-1, while lncRNA MSTRG.11809.1 had no binding site for Chi-miR-433. In conclusion, this study aims to further analyze the molecular regulation mechanism of hair follicle development and to lay a theoretical foundation for revealing the regulation mechanism of cashmere hair follicle growth.