In Vivo Reductionist Approach Identifies miR-15a Protecting Mice From Obesity

BACE1 inhibition via miR-6838-5p overexpression inhibits insulin resistance and the immune response in HFD-induced obesity in mice model

CONTEXT

Obesity is a chronic inflammatory disorder, which promotes the progression of metabolic disorders. MicroRNA (miR)-6838-5p is dysregulated and participates in the progression of several disorder models.

OBJECTIVE

To explore the role and mechanism of miR-6838-5p in insulin resistance.

METHODS

Mice were fed with high-fat diet (HFD) to construct an obesity animal model. The role of miR-6838-5p was evaluated by insulin tolerance test (ITT), glucose tolerance test (GTT), homeostasis model assessment of insulin resistance (HOMA-IR) analysis, enzyme-linked immunosorbent assay (ELISA) and western blot assays. The potential target of miR-6838-5p was screened through the starBase online website and confirmed by the luciferase assay.

RESULTS

HFD supply induced a prominent increase in the body weight, white adipose tissue (WAT) weight, the area under the curve (AUC) of GTT and ITT, HOMA-IR, the serum level of insulin and the serum concentrations and relative protein levels of interleukin (IL)-1β, IL-6 and monocyte chemoattractant protein-1 (MCP-1) accompanied with reduced levels of IL-10 in mice. The level of miR-6838-5p was reduced in HFD-fed mice. Upregulation of miR-6838-5p partly reversed the above-mentioned indicators. Moreover, miR-6838-5p directly targeted to β-site amyloid precursor protein cleaving enzyme1 (BACE1) and negatively regulated the BACE1 expression. Downregulation of BACE1 improved insulin sensitivity and inflammatory mediators release involving in AKT/GSK3β signaling pathway in HFD-fed mice. Besides, overexpression of BACE1 counteracted the depressant role of miR-6838-5p overexpression in insulin resistance and inflammatory factors release in HFD-fed mice.

CONCLUSION

MiR-6838-5p/BACE1 axis regulated insulin resistance and inflammatory factors release in HFD-fed mice.

Functional redundancy between glucocorticoid and mineralocorticoid receptors in mature corticotropin-releasing hormone neurons protects from obesity

OBJECTIVE

Here, we aimed to investigate the role of glucocorticoid and mineralocorticoid receptors (GRs and MRs, respectively) in the regulation of energy homeostasis.

METHODS

We used three mouse models with simultaneous deletion of GRs and MRs in either forebrain neurons, the paraventricular nucleus, or corticotropin-releasing hormone (CRH) neurons and compared them with wild-type controls or isolated knockout groups. In addition to body weight, food intake, energy expenditure, insulin sensitivity, fat/lean mass distribution, and plasma corticosterone levels, we also performed transcriptomic analysis of CRH neurons and assessed their response to melanocortinergic stimulation.

RESULTS

Similar to global double-knockout models, deletion of GRs and MRs specifically in mature CRH neurons resulted in obesity. Importantly, the latter was accompanied by insulin resistance, but not increased plasma corticosterone levels. Transcriptomic analysis of these neurons revealed upregulation of several genes involved in postsynaptic signal transduction, including the Ptk2b gene, which encodes proline-rich tyrosine kinase 2. Knockout of both nuclear receptors leads to upregulation of Ptk2b in CRH neurons, which results in their diminished responsiveness to melanocortinergic stimulation.

CONCLUSIONS

Our data demonstrate the functional redundancy of GRs and MRs in CRH neurons to maintain energy homeostasis and prevent obesity. Simultaneous targeting of both receptors might represent an unprecedented approach to counteract obesity.

Noodles, the all-in-one system for on-target efficiency analysis of CRISPR guide RNAs

The efficiency of clustered regularly interspaced short palindromic repeats (CRISPR) guide RNA (gRNA) targeting is critical for CRISPR associated protein 9 (Cas9)-dependent genomic modifications. Here, we developed Noodles, an all-in-one system to test the on-target activity of gRNAs easily and efficiently. Single-strand annealing repair mechanism of the split luciferase gene allows a positive selection of gRNAs efficiently driving nuclease activity of Cas9 from Streptococcus pyogenes (SpCas9). Our system can reliably validate in silico-predicted gRNAs before implementing them for in vitro and in vivo applications. Altogether, Noodles might be an asset for researchers and bioengineers, saving their time and efforts, while keeping the screening efficient and sensitive. •All-in-one dual-luciferase system to easily probe on-target activity of gRNAs based on homology-directed repair mechanism.•Easy-to-subclone spCas9-based 2-plasmid system comprising Renilla luciferase for transfection efficiency control.