CircDOCK7 facilitates the proliferation and adipogenic differentiation of chicken abdominal preadipocytes through the gga-miR-301b-3p/ACSL1 axis

Abstract

Background Abdominal fat deposition depends on both the proliferation of preadipocytes and their maturation into adipocytes, which is a well-orchestrated multistep process involving many regulatory molecules. Circular RNAs (circRNAs) have emergingly been implicated in mammalian adipogenesis. However, circRNA-mediated regulation in chicken adipogenesis remains unclear. Our previous circRNA sequencing data identified a differentially expressed novel circRNA, 8:27,886,180|27,889,657, during the adipogenic differentiation of chicken abdominal preadipocytes. This study aimed to investigate the regulatory role of circDOCK7 in the proliferation and adipogenic differentiation of chicken abdominal preadipocytes, and explore its molecular mechanisms of competing endogenous RNA underlying chicken adipogenesis. Results Our results showed that 8:27,886,180|27,889,657 is an exonic circRNA derived from the head-to-tail splicing of exons 19–22 of the dedicator of cytokinesis 7 (DOCK7) gene, abbreviated as circDOCK7. CircDOCK7 is mainly distributed in the cytoplasm of chicken abdominal preadipocytes and is stable because of its RNase R resistance and longer half-life. CircDOCK7 is significantly upregulated in the abdominal fat tissues of fat chickens compared to lean chickens, and its expression gradually increases during the proliferation and adipogenic differentiation of chicken abdominal preadipocytes. Functionally, the gain- and loss-of-function experiments showed that circDOCK7 promoted proliferation, G0/G1- to S-phase progression, and glucose uptake capacity of chicken abdominal preadipocytes, in parallel with adipogenic differentiation characterized by remarkably increased intracellular lipid droplet accumulation and triglyceride and acetyl coenzyme A content in differentiated chicken abdominal preadipocytes. Mechanistically, a pull-down assay and a dual-luciferase reporter assay confirmed that circDOCK7 interacted with gga-miR-301b-3p, which was identified as an inhibitor of chicken abdominal adipogenesis. Moreover, the ACSL1 gene was demonstrated to be a direct target of gga-miR-301b-3p. Chicken ACSL1 protein is localized in the endoplasmic reticulum and mitochondria of chicken abdominal preadipocytes and acts as an adipogenesis accelerator. Rescue experiments showed that circDOCK7 could counteract the inhibitory effects of gga-miR-301b-3p on ACSL1 mRNA abundance as well as the proliferation and adipogenic differentiation of chicken abdominal preadipocytes. Conclusions CircDOCK7 serves as a miRNA sponge that directly sequesters gga-miR-301b-3p away from the ACSL1 gene, thus augmenting adipogenesis in chickens. These findings may elucidate a new regulatory mechanism underlying abdominal fat deposition in chickens.

RNA-Seq Analysis Revealed circRNAs and Genes Associated with Abdominal Fat Deposition in Ducks

“…For example, chi-circ_0006511 has been shown to regulate the expression of CD36 by adsorbing miR-87, significantly reducing the differentiation of goat intramuscular adipocytes [10]. Additionally, the cytoplasmic exon of circDOCK7 acts as an miRNA sponge, sequestering gga-miR-301b-3p from ACSL1, which increases ACSL1 mRNA levels after transcription, facilitating the proliferation and differentiation of adipocytes [34]. In this study, we constructed 18,283 circRNA-miRNA-mRNA targeting relationships involving 67 circRNAs, 14 miRNAs, and 856 mRNAs.…”

Lipid Droplet–Mitochondria Contacts in Health and Disease

“…ACSL1 is crucial for fatty acid metabolism, activating fatty acids for β-oxidation in mitochondria and regulating LD formation and lipolysis. Its activity is closely tied to the cell's metabolic status and influences LD-mitochondria interactions [53,54].…”