Mutation c.-379 C>T in DGAT1 affects intramyocellular lipid content by altering MYOD1 binding affinity.

Intramuscular fat (IMF) is one of the most important indexes of pork taste quality. Diacylglycerol acyltransferase 1 (DGAT1), belonging to the acyl-coenzyme A: DGAT enzymes family, is a rate-limiting enzyme responsible for the final step of triglyceride (TG) synthesis. It is involved in TG storage in skeletal muscle; however, the underlying mechanism is not well understood. This study aimed to uncover functional mutations that can influence DGAT1 expression and consequently affect IMF deposition in pork. Two experimental groups containing individuals with high and low IMF content (6.23 ± 0.20 vs. 1.25 ± 0.05, p < 0.01) were formed from 260 Duroc × Large White × Yorkshire (D × L × Y) cross-bred pigs. A novel SNP c.-379 C>T was uncovered in the DGAT1 gene using comparative sequencing with pool DNA of high- and low-IMF groups. The IMF content of CT genotype individuals (3.19 ± 0.11%) was higher than that of CC genotype individuals (2.86 ± 0.11%) when analyzing 260 D × L × Y pigs (p < 0.05). The DGAT1 expression levels revealed a significant positive correlation with IMF content (r = 0.33, p < 0.01). Luciferase assay revealed that the DGAT1 promoter with the c.-379 T allele has a higher transcription activity than that bearing the C allele in C2C12 myoblast cells, but not in 3T3-L1 pre-adipocytes. Online prediction followed by chromatin immunoprecipitation-polymerase chain reaction assay confirmed that myogenic determination factor 1 (MYOD1) binds to the DGAT1 promoter with the c.-379 C allele but not the T allele. In vitro experiments demonstrated that MYOD1 represses DGAT1 transcription and lipogenesis. As a muscle-specific transcription factor, MYOD1 can inhibit the transcription of DGAT1 with the c.-379 C allele in muscle cells. However, in the absence of MYOD1 binding to the mutated DGAT1 promoter with the c.-379 T allele, DGAT1 expresses at a higher level in the muscle cells of the c.-379 T genotype, leading to more intramyocellular lipid accumulation than in the muscle cells of the c.-379 C genotype. The SNP c.-379 C>T in the promoter region of the DGAT1 gene provides a promising molecular marker for improving pork IMF content without affecting other fat depots.

The development and controversy of competitive endogenous RNA hypothesis in non-coding genes.

As a momentous post-transcriptional regulator, microRNAs (miRNAs) are attracting more and more attention. The classical miRNAs regulated mechanism shows it binds to the targets' 3'UTR thus play the role in post-transcription. Meanwhile, single miRNA can target multiple genes, so those should compete to bind that miRNA. Vice versa, single gene can sponge mass of miRNAs as well. Thus the competitive endogenous RNAs (ceRNAs) hypothesis was put forward in 2011. The ceRNA hypothesis has made huge achievements, in particular in non-coding genes, which including long non-coding RNAs (lncRNAs), circle RNAs (circRNAs) and pseudogenes, even viral transcripts. It also contributed greatly to epigenetics development. However, an increasing number of controversies have occurred with applause. Based on this situation, this review introduces something in detail about the ceRNAs hypothesis achieved in lncRNAs, circRNAs, pseudogenes and viral transcripts, respectively. Meanwhile, it also covers controversy of the ceRNAs hypothesis.

MiR-144-3p Targets FoxO1 to Reduce Its Regulation of Adiponectin and Promote Adipogenesis.

MicroRNAs (miRNAs), as a series of important short-chain non-coding RNAs, play an important post-transcriptional role in many biological activities, including adipogenesis. miR-144 is significantly upregulated in type II diabetes (T2D), and is considered to be an important biomarker for T2D. However, although the occurrence of T2D is inextricably linked to adipogenesis, whether miR-144 directly regulates adipogenesis remains to be further explored. In this paper, we demonstrate that miR-144 has a higher expression level in a porcine high backfat group, and it has a significant positive effect on promoting the differentiation of pre-adipocytes. FoxO1 is a target gene of miR-144, and inhibits the differentiation of pre-adipocytes. On the other hand, we demonstrate that FoxO1 can bind to the AdipoQ gene promoter, then regulate the AdipoQ expression by binding to the FoxO1 binding site in the AdipoQ promoter -1,499 to -1,489 bp and -1,238 to -1,228 bp regions, especially the -1,499 to -1,489 bp region. Meanwhile, miR-144 and FoxO1 co-expressional research has also shown that both factors regulate adipogenesis. To sum up, our research indicates that miR-144 targets FoxO1, thus reducing its expression and inhibiting its promotional effect on adiponectin, thereby alleviating the inhibitory effect of adiponectin on adipogenesis.