LncRNA IMFlnc1 promotes porcine intramuscular adipocyte adipogenesis by sponging miR-199a-5p to up-regulate CAV-1

Transcriptome profiling of longissimus dorsi during different prenatal stages to identify genes involved in intramuscular fat deposition in lean and obese pig breeds

BACKGROUND

There was significant difference in muscle development between fat-type and lean-type pig breeds.

METHODS AND RESULTS

In current study, transcriptome analysis and bioinformatics analysis were used to compare the difference in longissimus dorsi (LD) muscle at three time-points (38 days post coitus (dpc), 58 dpc, and 78 dpc ) between Huainan (HN) and Large white (LW) pig breeds. A total of 24500 transcripts were obtained in 18 samples, and 2319, 2799, and 3713 differently expressed genes (DEGs) were identified between these two breeds at 38 dpc, 58 dpc, and 78 dpc, respectively. And the number and foldchange of DEGs were increased, the alternative splice also increased. The cluster analysis of DEGs indicated the embryonic development progress of LD muscle between these two breeds was different. There were 539 shared DEGs between HN and LW at three stages, and the top-shared DEGs were associated with muscle development and lipid deposition, such as KLF4, NR4A1, HSP70, ZBTB16 and so on.

CONCLUSIONS

The results showed DEGs between Huainan (HN) and Large white (LW) pig breeds, and contributed to the understanding the muscle development difference between HN and LW, and provided basic materials for improvement of meat quality.

The role of lncFABP4 in modulating adipogenic differentiation in buffalo intramuscular preadipocytes

Intramuscular fat (IMF) is a crucial determinant of meat quality and is influenced by various regulatory factors. Despite the growing recognition of the important role of long noncoding RNAs (lncRNAs) in IMF deposition, the mechanisms underlying buffalo IMF deposition remain poorly understood. In this study, we identified and characterized a lncRNA, lncFABP4, which is transcribed from the antisense strand of fatty acid-binding protein 4 (FABP4). lncFABP4 inhibited cell proliferation in buffalo intramuscular preadipocytes. Moreover, lncFABP4 significantly increased intramuscular preadipocyte differentiation, as indicated by an increase in the expression of the adipogenic markers peroxisome proliferator-activated receptor gamma (PPARG), CCAAT enhancer binding protein alpha (C/EBPα), and FABP4. Mechanistically, lncFABP4 was found to have the potential to regulate downstream gene expression by participating in protein-protein interaction pathways. These findings contribute to further understanding of the intricate mechanisms through which lncRNAs modulate intramuscular adipogenesis in buffaloes.

lncRNA Hnscr Regulates Lipid Metabolism by Mediating Adipocyte Lipolysis

Obesity is a process of fat accumulation due to the imbalance between energy intake and consumption. Long noncoding RNA (lncRNA) Hnscr is crucial for metabolic regulation, but its roles in lipid metabolism during obesity are still unknown. In this article, we found that the expression of Hnscr gradually decreased in adipose tissues of diet-induced obese mice. Furthermore, the deletion of Hnscr promoted an increase in body weight and adipose tissue weight by upregulating the expression of lipogenesis genes and downregulating lipolysis genes in inguinal white adipose tissue (iWAT) and brown adipose tissue. In vitro knockdown of Hnscr in adipocytes resulted in reduced lipolysis of adipocytes. Overexpression of Hnscr by adenovirus or drug mimics showed the opposite. Mechanistically, Hnscr regulated adipose lipid metabolism by mediating the cyclic adenosine monophosphate/protein kinase A signaling pathway. This study identifies the initial characterization of Hnscr as a critical modifier that regulates lipid metabolism, suggesting that lncRNA Hnscr is a potential target for treating obesity.

Diverse Regulatory Manners and Potential Roles of lncRNAs in the Developmental Process of Asian Honey Bee (Apis cerana) Larval Guts

Long non-coding RNAs (lncRNAs) are crucial modulators in a variety of biological processes, such as gene expression, development, and immune defense. However, little is known about the function of lncRNAs in the development of Asian honey bee (Apis cerana) larval guts. Here, on the basis of our previously obtained deep-sequencing data from the 4-, 5-, and 6-day-old larval guts of A. cerana workers (Ac4, Ac5, and Ac6 groups), an in-depth transcriptome-wide investigation was conducted to decipher the expression pattern, regulatory manners, and potential roles of lncRNAs during the developmental process of A. cerana worker larval guts, followed by the verification of the relative expression of differentially expressed lncRNAs (DElncRNAs) and the targeting relationships within a competing endogenous RNA (ceRNA) axis. In the Ac4 vs. Ac5 and Ac5 vs. Ac6 comparison groups, 527 and 498 DElncRNAs were identified, respectively, which is suggestive of the dynamic expression of lncRNAs during the developmental process of larval guts. A cis-acting analysis showed that 330 and 393 neighboring genes of the aforementioned DElncRNAs were respectively involved in 29 and 32 functional terms, such as cellular processes and metabolic processes; these neighboring genes were also respectively engaged in 246 and 246 pathways such as the Hedgehog signaling pathway and the Wnt signaling pathway. Additionally, it was found that 79 and 76 DElncRNAs as potential antisense lncRNAs may, respectively, interact with 72 and 60 sense-strand mRNAs. An investigation of competing endogenous RNA (ceRNA) networks suggested that 75 (155) DElncRNAs in the Ac4 vs. Ac5 (Ac5 vs. Ac6) comparison group could target 7 (5) DEmiRNAs and further bind to 334 (248) DEmRNAs, which can be annotated to 33 (29) functional terms and 186 (210) pathways, including 12 (16) cellular- and humoral-immune pathways (lysosome pathway, necroptosis, MAPK signaling pathway, etc.) and 11 (10) development-associated signaling pathways (Wnt, Hippo, AMPK, etc.). The RT-qPCR detection of five randomly selected DElncRNAs confirmed the reliability of the used sequencing data. Moreover, the results of a dual-luciferase reporter assay were indicative of the binding relationship between MSTRG.11294.1 and miR-6001-y and between miR-6001-y and ncbi_107992440. These results demonstrate that DElncRNAs are likely to modulate the developmental process of larval guts via the regulation of the source genes' transcription, interaction with mRNAs, and ceRNA networks. Our findings not only yield new insights into the developmental mechanism underlying A. cerana larval guts, but also provide a candidate ceRNA axis for further functional dissection.

Transcriptome analysis of mRNAs, lncRNAs, and miRNAs in the skeletal muscle of Tibetan chickens at different developmental stages

Introduction: As a valuable genetic resource, native birds can contribute to the sustainable development of animal production. Tibetan chickens, known for their special flavor, are one of the important local poultry breeds in the Qinghai-Tibet Plateau. However, Tibetan chickens have a slow growth rate and poor carcass traits compared with broilers. Although most of the research on Tibetan chickens focused on their hypoxic adaptation, there were fewer studies related to skeletal muscle development. Methods: Here, we performed the transcriptional sequencing of leg muscles from Tibetan chicken embryos at E (embryonic)10, E14, and E18. Results: In total, 1,600, 4,610, and 2,166 DE (differentially expressed) mRNAs, 210, 573, and 234 DE lncRNAs (long non-coding RNAs), and 52, 137, and 33 DE miRNAs (microRNAs) were detected between E10 and E14, E10 and E18, and E14 and E18, respectively. Functional prediction showed several DE mRNAs and the target mRNAs of DE lncRNAs and DE miRNAs were significantly enriched in sarcomere organization, actin cytoskeleton organization, myofibril, muscle fiber development, and other terms and pathways related to muscle growth and development. Finally, a lncRNA-miRNA-mRNA ceRNA (competing endogenous RNA) network associated with muscle growth and development, which contained 6 DE lncRNAs, 13 DE miRNAs, and 50 DE mRNAs, was constructed based on the screened DE RNAs by Gene Ontology (GO) enrichment. These DE RNAs may play a critical regulatory role in the skeletal muscle development of chickens. Discussion: The results provide a genomic resource for mRNAs, lncRNAs, and miRNAs potentially involved in the skeletal muscle development of chickens, which lay the foundation for further studies of the molecular mechanisms underlying skeletal muscle growth and development in Tibetan chickens.

The emerging roles of circRNAs in traits associated with livestock breeding

Many indicators can be used to evaluate the productivity and quality of livestock, such as meat and milk production as well as fat deposition. Meat and milk production are measures of livestock performance, while fat deposition affects the taste and flavor of the meat. The circRNAs, are non-coding RNAs, that are involved in the regulation of all these three traits. We review the functions and mechanisms of circRNAs in muscle and fat development as well as lactation to provide a theoretical basis for circRNA research in animal husbandry. Various phenotypic changes presented in livestock may be produced by different circRNAs. Our current concern is how to use the roles played by circRNAs to our advantage to produce the best possible livestock. Hence, we describe the advantages and disadvantages of knockout techniques for circRNAs. In addition, we also put forward our thoughts regarding the mechanism and network of circRNAs to provide researchers with novel ideas of how molecular biology can help us advance our goals in animal farming. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.

Transcriptome Analysis Reveals the Age-Related Developmental Dynamics Pattern of the Longissimus Dorsi Muscle in Ningxiang Pigs

The growth and development of the Longissimus Dorsi muscle are complex, playing an important role in the determination of pork quality. The study of the Longissimus Dorsi muscle at the mRNA level is particularly crucial for finding molecular approaches to improving meat quality in pig breeding. The current study utilized transcriptome technology to explore the regulatory mechanisms of muscle growth and intramuscular fat (IMF) deposition in the Longissimus Dorsi muscle at three core developmental stages (natal stage on day 1, growing stage on day 60, and finishing stage on day 210) in Ningxiang pigs. Our results revealed 441 differentially expressed genes (DEGs) in common for day 1 vs. day 60 and day 60 vs. day 210, and GO (Gene Ontology) analysis showed that candidate genes RIPOR2, MEGF10, KLHL40, PLEC, TBX3, FBP2, and HOMER1 may be closely related to muscle growth and development, while KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis showed that DEGs (UBC, SLC27A5, RXRG, PRKCQ, PRKAG2, PPARGC1A, PLIN5, PLIN4, IRS2, and CPT1B) involved the PPAR (Peroxisome Proliferator-Activated Receptor) signaling pathway and adipocytokine signaling pathway, which might play a pivotal role in the regulation of IMF deposition. PPI (Protein-Protein Interaction Networks) analysis found that the STAT1 gene was the top hub gene. Taken together, our results provide evidence for the molecular mechanisms of growth and development and IMF deposition in Longissimus Dorsi muscle to optimize carcass mass.

Research progress of non-coding RNAs regulation on intramuscular adipocytes in domestic animals

Intramuscular fat (IMF) is the main determinant of the economic value of domestic animal meat, and has a vital impact on the sensory quality characteristics, while the content of IMF is mainly determined by the size and number of intramuscular adipocytes. In recent years, due to the development of sequencing technology and omics technology, a large number of non-coding RNAs have been identified in intramuscular adipocytes. Non-coding RNAs are a kind of RNA regulatory factors with biological functions but without translation function, which mainly include microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). These non-coding RNAs regulate the key genes of intramuscular adipocyte growth and development at post-transcriptional level through a variety of regulatory mechanisms, and affect the number and size of intramuscular adipocytes, thus affecting the content of IMF. Here, the review summarizes the candidate non-coding RNAs (miRNAs, lncRNAs, circRNAs) and genes involved in the regulation of intramuscular adipocytes, the related regulation mechanism and signaling pathways, in order to provide reference for further clarifying the molecular regulation mechanism of non-coding RNAs on intramuscular adipocytes in domestic animals.

Mechanisms of circRNA/lncRNA-miRNA interactions and applications in disease and drug research

In recent years, breakthroughs in bioinformatics have been made with the discovery of many functionally significant non-coding RNAs (ncRNAs). The discovery of these ncRNAs has further demonstrated the multi-level characteristics of intracellular gene expression regulation, which plays an important role in assisting diagnosis, guiding clinical drug use and determining prognosis in the treatment process of various diseases. microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) are the three major types of ncRNAs that interact with each other. Studies have shown that lncRNAs and circRNAs can sponge miRNAs, thereby influencing normal physiological processes and regulating mRNA expression and, thus, the physiological state of cells. This paper summarizes the mechanism of action and research progress of the three ncRNA and seven types of modalities. This summary is intended to provide new ideas for diagnosing and treating diseases and researching and developing new drugs.

Competing endogenous RNA network construction based on long non-coding RNAs, microRNAs, and mRNAs related to fat deposition in Songliao black swine

China has a long history of pig breeding and a number of local breeds. The Songliao Black pig, bred in China in 2009, shows high variation in backfat thickness and therefore is well-suited to fat deposition research. Fat deposition is a complex trait, and the underlying regulatory factors are not fully characterized. In this study, the molecular basis of fat deposition traits was evaluated by comparisons between three individuals with extremely high-backfat thickness and three with extremely low-backfat thickness selected from 53 gilts. Subcutaneous adipose tissues of the back were collected for strand-specific library RNA sequencing (RNA-seq) and small RNA-seq. We identified 13 184 mRNAs, 2046 long non-coding (lnc)RNAs, and 494 micro (mi)RNAs by high-throughput sequencing. Furthermore, we detected 150 differentially expressed mRNAs, 66 differentially expressed lncRNAs, and eight differentially expressed miRNAs. A functional enrichment analysis indicated that these genes are involved in multiple fat metabolism-related pathways, including positive regulation of fat cell differentiation, and fat digestion and absorption. We used various algorithms (miRanda, TargetScan, and RNAhybrid) to predict targeting relationships and constructed a competing endogenous RNA network containing seven lncRNAs, three miRNAs, and six mRNAs. All these genes were differentially expressed between the extremely high and low backfat thickness groups or enriched in pathways related to fat metabolism. Our results provide insight into the regulatory mechanisms by which non-coding RNAs and their target genes influence backfat deposition in pigs. Furthermore, our newly constructed competing endogenous RNA (lncRNA-miRNA-mRNA) network provides a basis for further exploration of fat deposition traits and non-coding RNA functions.

Co-expression analysis of long non-coding RNAs and mRNAs involved in intramuscular fat deposition in Muchuan black-bone chicken

The intramuscular fat (IMF) content in meat products is positively correlated with meat quality, making it an important consumer trait. Long non-coding RNAs (lncRNAs) play central roles in regulating various biological processes, but little is currently known about the mechanisms by which they regulate IMF deposition in chickens. This study sampled the breast muscles of chickens with high (H) and low (L) IMF content and constructed six small RNA libraries. High-throughput sequencing technology was used to profile the breast muscle transcriptome (lncRNA and mRNA) and to identify the differentially expressed lncRNAs (DELs) and mRNAs (DEGs) between the H and L groups. In total, 263 DELs (118 up-regulated and 145 down-regulated lncRNAs) and 443 DEGs (203 up-regulated and 240 down-regulated genes) were identified between the two groups. To analyse the DELs-DEGs interaction network, co-expression analysis was conducted to identify lncRNA-mRNA pairs. In total, 19,270 lncRNA/mRNA pairs were identified, including 16,398 significant correlation pairs that presented as positive and 2872 pairs that presented as negative. The lncRNA-mRNA network comprised 263 lncRNA nodes and 440 mRNA nodes. Pathway analysis, using the Kyoto Encyclopedia of Genes and Genomes, indicated that pathways associated with fat deposition and lipid metabolism such as the MAPK, PPAR, GnRH, ErbB and calcium signalling pathways, fatty acid elongation and fatty acid metabolism. Overall, the study identified potential candidate lncRNAs, genes and regulatory networks associated with chicken IMF deposition. These findings provide new insights to help clarify the regulatory mechanisms of IMF deposition in chickens which can be used to improve the IMF content in poultry.

Comprehensive investigation and regulatory function of lncRNAs engaged in western honey bee larval immune response to Ascosphaera apis invasion

Ascosphaera apis is a fungal pathogen that exclusively infects bee larvae, causing chalkbrood disease, which results in severe damage for beekeeping industry. Long non-coding RNAs (lncRNAs) are versatile regulators in various biological processes such as immune defense and host-pathogen interaction. However, expression pattern and regulatory role of lncRNAs involved in immune response of bee host to A. apis invasion is still very limited. Here, the gut tissues of Apis mellifera ligustica 4-, 5-, and 6-day-old larvae inoculated by A. apis spores (AmT1, AmT2, and AmT3 groups) and corresponding un-inoculated larval guts (AmCK1, AmCK2, and AmCK3 groups) were prepared and subjected to deep sequencing, followed by identification of lncRNAs, analysis of differentially expressed lncRNAs (DElncRNAs), and investigation of competing endogenous RNA (ceRNA) network. In total, 3,746 A. m. ligustica lncRNAs were identified, including 78 sense lncRNAs, 891 antisense lncRNAs, 1,893 intergenic lncRNAs, 346 bidirectional lncRNAs, and 210 intronic lncRNAs. In the 4-, 5-, and 6- comparison groups, 357, 236, and 505 DElncRNAs were discovered. Additionally, 217, 129, and 272 DElncRNAs were respectively predicted to regulate neighboring genes via cis-acting manner, and these targets were associated with a series of GO terms and KEGG pathways of great importance, such as response to stimulus and Jak-STAT signaling pathway. Moreover, 197, 95, and 356 DElncRNAs were observed to target 10, eight, and 21 DEmiRNAs and further target 147, 79, and 315 DEmRNAs, forming complex regulatory networks. Further investigation suggested that these targets were engaged in several key cellular and humoral immune pathways, such as phagosome and MAPK signaling pathway. Ultimately, the expression trends of nine randomly selected DElncRNAs were verified by RT-qPCR, confirming the authenticity and reliability of our transcriptome data. Findings in this current work not only provide candidate DElncRNAs for functional study, but also lay a foundation for unclosing the mechanism underlying DElncRNA-regulated larval immune responses to A. apis invasion.

Identification and characterization of circRNAs related to meat quality during embryonic development of the longissimus dorsi muscle in two pig breeds

Meat quality, an important economic trait, is regulated by many factors, especially by genetic factors, including coding genes, miRNAs, and lncRNAs. Recent studies have elucidated that circRNAs also play a key role in muscle development and lipid deposition. However, the functions and regulatory mechanisms of circRNAs in meat quality remain mostly unknown. The circRNA expression profiles between Huainan pigs (Chinese indigenous pigs, fat-type, Huainan HN) and Large White pigs (Western commercial pigs, lean-type, LW) in the longissimus dorsi (LD) muscle at 38, 58, and 78 days post conception (dpc) were compared by sequencing. In total, 39,887 circRNAs were identified in 18 samples, and 60, 78, and 86 differentially expressed circRNAs (DECs) were found at the three stages mentioned above between these two breeds. The parent genes of DECs were enriched in myogenesis, proliferation, adipogenesis and muscle fiber-type transition. The circRNA-miRNA interaction networks included 38 DECs and 47 miRNAs, and these miRNAs were involved in muscle development and lipid metabolism. Two shared DECs (circ_0030593 and circ_0032760) of these three stages were selected, their head-to-tail junction sites were validated by Sanger sequencing, and RT‒qPCR results suggested that these two DECs might be involved in intramuscular fat deposition. These findings provide a basis for understanding the role of circRNAs in meat quality.

Identification of Candidate Genes and Regulatory Competitive Endogenous RNA (ceRNA) Networks Underlying Intramuscular Fat Content in Yorkshire Pigs with Extreme Fat Deposition Phenotypes

Intramuscular fat (IMF) content is vital for pork quality, serving an important role in economic performance in pig industry. Non-coding RNAs, with mRNAs, are involved in IMF deposition; however, their functions and regulatory mechanisms in porcine IMF remain elusive. This study assessed the whole transcriptome expression profiles of the Longissimus dorsi muscle of pigs with high (H) and low (L) IMF content to identify genes implicated in porcine IMF adipogenesis and their regulatory functions. Hundreds of differentially expressed RNAs were found to be involved in fatty acid metabolic processes, lipid metabolism, and fat cell differentiation. Furthermore, combing co-differential expression analyses, we constructed competing endogenous RNAs (ceRNA) regulatory networks, showing crosstalk among 30 lncRNAs and 61 mRNAs through 20 miRNAs, five circRNAs and 11 mRNAs through four miRNAs, and potential IMF deposition-related ceRNA subnetworks. Functional lncRNAs and circRNAs (such as MSTRG.12440.1, ENSSSCT00000066779, novel_circ_011355, novel_circ_011355) were found to act as ceRNAs of important lipid metabolism-related mRNAs (LEP, IP6K1, FFAR4, CEBPA, etc.) by sponging functional miRNAs (such as ssc-miR-196a, ssc-miR-200b, ssc-miR10391, miR486-y). These findings provide potential regulators and molecular regulatory networks that can be utilized for research on IMF traits in pigs, which would aid in marker-assisted selection to improve pork quality.

miR-381-3p Inhibits Intramuscular Fat Deposition through Targeting FABP3 by ceRNA Regulatory Network

Intramuscular fat (IMF) deposition is an important determinant of pork quality and a complex process facilitated by non-coding ceRNAs. In this study, 52 Berkshire × Anqing Sixwhite crossbred pigs were slaughtered to measure eight carcass and pork quality traits. Whole-transcriptome sequencing analysis was performed using longissimus dorsi samples of six low- and high-IMF samples; 34 ceRNA networks, based on 881, 394, 158 differentially expressed (DE) lncRNAs, miRNAs, and mRNAs, were constructed. Following weighted gene co-expression network analysis between the low and high IMF, only one ceRNA, lncRNA4789/miR-381-3p/FABP3, that showed similar DE trend in longissimus dorsi tissue was retained. Dual-luciferase reporter assays further indicated that FABP3 was a direct, functional target of miR-381-3p, where miR-381-3p overexpression inhibited the mRNA and protein expression of FABP3. In addition, overexpressed lncRNA4789 attenuated the effect of miR-381-3p on FABP3 by sponging miR-381-3p. Cell function verification experiment demonstrated that miR-381-3p suppressed IMF deposition by inhibiting preadipocyte cell differentiation and lipid droplet deposition via the suppression of FABP3 expression in the peroxisome proliferator-activated receptor signalling pathway, whereas lncRNA4789 rescued FABP3 expression by sponging miR-381-3p. Our study may aid in identifying novel molecular markers for its optimization in IMF which is of importance in breeding for improving pork quality.

The long non-coding RNA lncMYOZ2 mediates an AHCY/MYOZ2 axis to promote adipogenic differentiation in porcine preadipocytes

Long non-coding RNAs (lncRNAs) play a vital role in regulating adipogenesis. However, the associated regulatory mechanisms have yet to be described in detail in pig. In this study, we demonstrate a critical role for lncMYOZ2 in adipogenesis from porcine preadipocytes. Specifically, lncMYOZ2 was more abundant in the adipose tissue of Mashen (fat-type) pigs than for Large White (lean-type) pigs, and knockdown of this lncRNA significantly inhibited the differentiation of porcine preadipocytes into adipocytes. Mechanistically, we used RNA pull-down and RIP assays to establish that lncMYOZ2 interacts with adenosylhomocysteinase (AHCY). Moreover, lncMYOZ2 knockdown increased promoter methylation of the target gene MYOZ2 and lowered its expression. Finally, we describe a positive regulatory role for MYOZ2 in adipogenesis. Collectively, these findings establish lncMYOZ2 as an important epigenetic regulator of adipogenesis via the aforementioned AHCY/MYOZ2 pathway, and provide insights into the role of lncRNAs in porcine adipose development.

Genome-wide characterization of lncRNAs and mRNAs in muscles with differential intramuscular fat contents

Meat quality is one of the most important traits in pig production. Long non-coding RNAs (lncRNAs) have been involved in diverse biological processes such as muscle development through regulating gene expression. However, studies on lncRNAs lag behind and a comparatively small number of lncRNAs have been identified in pigs. Also, the effects of lncRNAs on meat quality remain to be characterized. Here, we analyzed lncRNAs in longissimus thoracis (LT) and semitendinosus (ST) muscles, being different in meat quality, with RNA-sequencing technology. A total of 500 differentially expressed lncRNAs (DELs) and 2,094 protein-coding genes (DEGs) were identified. Through KEGG analysis on DELs, we first made clear that fat deposition might be the main reason resulting in the differential phenotype of LT and ST, for which cGMP–PKG and VEGF signaling pathways were the most important ones. In total, forty-one key DELs and 50 DEGs involved in the differential fat deposition were then characterized. One of the key genes, cAMP-response element binding protein 1, was selected to confirm its role in porcine adipogenesis with molecular biology methods and found that it promotes the differentiation of porcine preadipocytes, consistent with its higher expression level and intramuscular fat contents in LT than that in ST muscle. Furthermore, through integrated analysis of DELs and DEGs, transcription factors important for differential fat deposition were characterized among which BCL6 has the most target DEGs while MEF2A was targeted by the most DELs. The results provide candidate genes crucial for meat quality, which will contribute to improving meat quality with molecular-breeding strategies.

Differentially Expressed lncRNAs Related to the Development of Abdominal Fat in Gushi Chickens and Their Interaction Regulatory Network

Chickens are one of the most important sources of meat worldwide, and the growth status of abdominal fat is closely related to production efficiency. Long noncoding RNAs (lncRNAs) play an important role in lipid metabolism and deposition regulation. However, research on the expression profile of lncRNAs related to the development of abdominal fat in chickens after hatching and their interaction regulatory networks is still lacking. To characterize the lncRNA expression profile during the development of chicken abdominal fat, abdominal adipose tissues from 6-, 14-, 22-, and 30-week-old Chinese Gushi chickens were herein used to construct 12 cDNA libraries, and a total of 3,827 new lncRNAs and 5,466 previously annotated lncRNAs were revealed. At the same time, based on the comparative analysis of five combinations, 276 differentially expressed lncRNAs (DE-lncRNAs) were screened. Functional enrichment analysis showed that the predicted target genes of these DE-lncRNAs were significantly enriched in pathways related to the posttranscriptional regulation of gene expression, negative regulation of cell proliferation, cell adhesion and other biological processes, glycosphingolipid biosynthesis, PPAR signaling, fatty acid degradation, fatty acid synthesis and others. In addition, association analysis of the lncRNA transcriptome profile was performed, and DE-lncRNA-related lncRNA-mRNA, lncRNA-miRNA and lncRNA-miRNA-mRNA interaction regulatory networks were constructed. The results showed that DE-lncRNA formed a complex network with PPAR pathway components, including PPARD, ACOX1, ADIPOQ, CPT1A, FABP5, ASBG2, LPL, PLIN2 and related miRNAs, including mir-200b-3p, mir-130b-3p, mir-215-5p, mir-122-5p, mir-223 and mir-125b-5p, and played an important regulatory role in biological processes such as lipid metabolism, adipocyte proliferation and differentiation. This study described the dynamic expression profile of lncRNAs in the abdominal fat of Gushi chickens for the first time and constructed the DE-lncRNA interaction regulatory network. The results expand the number of known lncRNAs in chicken abdominal fat and provide valuable resources for further elucidating the posttranscriptional regulatory mechanism of chicken abdominal fat development or deposition.

Caveolin-1 Regulates Cellular Metabolism: A Potential Therapeutic Target in Kidney Disease

The kidney is an energy-consuming organ, and cellular metabolism plays an indispensable role in kidney-related diseases. Caveolin-1 (Cav-1), a multifunctional membrane protein, is the main component of caveolae on the plasma membrane. Caveolae are represented by tiny invaginations that are abundant on the plasma membrane and that serve as a platform to regulate cellular endocytosis, stress responses, and signal transduction. However, caveolae have received increasing attention as a metabolic platform that mediates the endocytosis of albumin, cholesterol, and glucose, participates in cellular metabolic reprogramming and is involved in the progression of kidney disease. It is worth noting that caveolae mainly depend on Cav-1 to perform the abovementioned cellular functions. Furthermore, the mechanism by which Cav-1 regulates cellular metabolism and participates in the pathophysiology of kidney diseases has not been completely elucidated. In this review, we introduce the structure and function of Cav-1 and its functions in regulating cellular metabolism, autophagy, and oxidative stress, focusing on the relationship between Cav-1 in cellular metabolism and kidney disease; in addition, Cav-1 that serves as a potential therapeutic target for treatment of kidney disease is also described.

LncIMF2 promotes adipogenesis in porcine intramuscular preadipocyte through sponging MiR-217

Intramuscular fat is positively related to meat quality including tenderness, flavor, and juiciness. Long noncoding RNA (LncRNA) plays a vital role in regulating adipogenesis. However, it is largely unknown about lncRNAs associated with porcine intramuscular adipocyte adipogenesis. In the present study, we focus on a novel LncRNA, which is named lncIMF2, associated with adipogenesis by our previous RNA-sequence analysis and bioinformatics analysis. We demonstrated LncIMF2 knockdown inhibited the proliferation of porcine intramuscular adipocytes while expression of cell cycle-related genes was decreased. Besides, we found LncIMF2 knockdown inhibited expression of adipogenic differentiation marker genes including PPARγ (Peroxisome proliferator-activated reporter gamma) and ATGL (Adipose triglyceride lipase). Similarly, overexpression of LncIMF2 promotes proliferation and differentiation of porcine intramuscular preadipocytes. Moreover, we proved that IncIMF2 acts as a molecular sponge for MicroRNA-217 (miR-217), which has been found associated with adipogenesis, thereby affecting the expression of the miR-217 target gene. Collectively, our findings will contribute to a deeper understanding of the role of LncRNA in pig IMF deposition for the improvement of meat quality.

Identification and functional prediction of long noncoding RNAs related to intramuscular fat content in Laiwu pigs

Objective

Intramuscular fat (IMF) is a critical economic indicator of pork quality. Studies on IMF among different pig breeds have been performed via high-throughput sequencing, but comparisons within the same pig breed remain unreported.

Methods

This study was performed to explore the gene profile and identify candidate long noncoding RNA (lncRNAs) and mRNAs associated with IMF deposition among Laiwu pigs with different IMF contents. Based on the longissimus dorsi muscle IMF content, eight pigs from the same breed and management were selected and divided into two groups: a high IMF (>12%, H) and low IMF group (<5%, L). Whole-transcriptome sequencing was performed to explore the differentially expressed (DE) genes between these two groups.

Results

The IMF content varied greatly among Laiwu pig individuals (2.17% to 13.93%). Seventeen DE lncRNAs (11 upregulated and 6 downregulated) and 180 mRNAs (112 upregulated and 68 downregulated) were found. Gene Ontology analysis indicated that the following biological processes played an important role in IMF deposition: fatty acid and lipid biosynthetic processes; the extracellular signal-regulated kinase cascade; and white fat cell differentiation. In addition, the peroxisome proliferator-activated receptor, phosphatidylinositol-3-kinase-protein kinase B, and mammalian target of rapamycin pathways were enriched in the pathway analysis. Intersection analysis of the target genes of DE lncRNAs and mRNAs revealed seven candidate genes associated with IMF accumulation. Five DE lncRNAs and 20 DE mRNAs based on the pig quantitative trait locus database were identified and shown to be related to fat deposition. The expression of five DE lncRNAs and mRNAs was verified by quantitative real time polymerase chain reaction (qRT-PCR). The results of qRT-PCR and RNA-sequencing were consistent.

Conclusion

These results demonstrated that the different IMF contents among pig individuals may be due to the DE lncRNAs and mRNAs associated with lipid droplets and fat deposition.

LncRNA MIR31HG is activated by STAT1 and facilitates glioblastoma cell growth via Wnt/β-catenin signaling pathway

Long non-coding RNAs (lncRNAs) have been reported to biologically regulate tumor progression. LncRNA MIR31HG has been identified as an oncogene in several cancer types, but its role and mechanism in glioblastoma (GBM) remain to be explored. In the present study, we detected strongly-expressed MIR31HG in GBM cells through RT-qPCR analysis. Through loss-of-function assays, we uncovered that MIR31HG exerted its oncogenic property in GBM through boosting cell proliferation and suppressing the apoptosis. Mechanistically, STAT1 was found to be as a transcription factor and played a part in activating the transcription of MIR31HG with upregulating the expression of MIR31HG in GBM. Moreover, high MIR31HG level was confirmed to induce the activation of Wnt/β-catenin signaling pathway in a variety of cancers. From subcellular fractionation and western blot assays, it was displayed that MIR31HG activated Wnt/β-catenin signaling pathway through enhancing the nuclear translocation of β-catenin. Rescue assays showed that the treatment of LiCl countervailed MIR31HG depletion-induced inhibition on GBM cell growth. In conclusion, STAT1-induced upregulation of lncRNA MIR31HG facilitates GBM cell growth by activating Wnt/β-catenin signaling pathway.

The role of long noncoding RNAs in livestock adipose tissue deposition - A review

With the development of sequencing technology, numerous, long noncoding RNAs (lncRNAs) have been discovered and annotated. Increasing evidence has shown that lncRNAs play an essential role in regulating many biological and pathological processes, especially in cancer. However, there have been few studies on the roles of lncRNAs in livestock production. In animal products, meat quality and lean percentage are vital economic traits closely related to adipose tissue deposition. However, adipose tissue accumulation is also a pivotal contributor to obesity, diabetes, atherosclerosis, and many other diseases, as demonstrated by human studies. In livestock production, the mechanism by which lncRNAs regulate adipose tissue deposition is still unclear. In addition, the phenomenon that different animal species have different adipose tissue accumulation abilities is not well understood. In this review, we summarize the characteristics of lncRNAs and their four functional archetypes and review the current knowledge about lncRNA functions in adipose tissue deposition in livestock species. This review could provide theoretical significance to explore the functional mechanisms of lncRNAs in adipose tissue accumulation in animals.