Akirin2 could promote the proliferation but not the differentiation of duck myoblasts via the activation of the mTOR/p70S6K signaling pathway

Role of nuclear protein Akirin in the modulation of female reproduction in Nilaparvata lugens (Hemiptera: Delphacidae)

Introduction: Akirin as a highly conserved transcription factor, exerts a profound influence on the growth, development, immune response, and reproductive processes in animals. The brown planthopper (BPH), Nilaparvata lugens, a major pest in rice production in Asia, possesses high reproductive capacity, a critical factor contributing to reduced rice yields. The aims of this study were to demonstrate the regulatory role of Akirin in the reproduction of BPH. Methods: In this study, quantitative PCR (qPCR) was used to detect the mRNA expression of genes. RNA interference (RNAi) was used to downregulate the expression of Akirin gene, and RNA sequencing (RNA-seq) was used to screen for differentially expressed genes caused by Akirin downregulation. Hormone contents were measured with the enzyme linked immunosorbent assay (ELISA), and protein content was evaluated with the bicinchoninic acid (BCA) method. Results: Using BPH genome data, we screened for an Akirin gene (NlAkirin). An analysis of tissue-specific expressions showed that NlAkirin was expressed in all tissues tested in female BPH, but its expression level was highest in the ovary. After inhibiting the mRNA expression of NlAkirin in BPH females, the number of eggs laid, hatching rate, and number of ovarioles decreased. Transcriptome sequencing was performed, following a NlAkirin double-stranded RNA treatment. Compared with the genes of the control, which was injected with GFP double-stranded RNA, there were 438 upregulated genes and 1012 downregulated genes; the expression of vitellogenin (Vg) and vitellogenin receptor (VgR) genes as well as the mRNA expression of genes related to the target of rapamycin (TOR), juvenile hormone (JH), and insulin pathways involved in Vg synthesis was significantly downregulated. As a result of NlAkirin knockdown, the titers of JH III and Ecdysone (Ecd) were downregulated in unmated females but returned to normal levels in mated females. The ovarian protein contents in both unmated and mated females were downregulated. Discussion and conclusion: Our results suggest that NlAkirin affects female BPH reproduction by regulating the mRNA expression of genes related to the Vg, VgR, TOR, JH, and insulin signaling pathways, in addition to the titers of JH III and Ecd. The findings of this research provide novel insights into the regulatory role of Akirin in insect reproductive capacity.

Phenotypic Identification, Genetic Characterization, and Selective Signal Detection of Huitang Duck

The Huitang duck (HT), a long-domesticated elite local breed from Hunan Province, China, with excellent meat quality, has not had its population genetic structure and genomic selective sweeps extensively studied to date. This study measured the phenotypic characteristics of HT and conducted comparative analysis between HT and 16 different duck breeds, including wild, indigenous, and meat breeds, to characterize its population structure and genetic potential. The results revealed that HT is a dual-purpose indigenous breed with a genetic background closely related to the Youxian sheldrake and Linwu ducks. In the selective sweep analysis between HT and Linwu ducks, genes such as PLCG2, FN1, and IGF2BP2, which are associated with muscle growth and development, were identified near the 27 selection signals. The comparison between HT and Jinding ducks revealed 68 selective signals that contained important genes associated with ovarian development (GRIK4, MAP3K8, and TGIF1) and egg-laying behaviors (ERBB4). Selective sweep analysis between HT and Youxian sheldrake ducks found 93 selective regions covering genes related to both meat (IGF1R and IGFBP5) and egg-production (FOXO3 and ITPR1) traits. Our study may provide novel knowledge for exploring the population structure and genetic potential of HT, offering a theoretical basis for its breeding strategies in the future.

The identification of nuclear factor Akirin with immune defense role in silkworm, Bombyx mori

Akirins, highly conserved nuclear factors, regulate diverse physiological processes such as innate immunity. The biological functions of Akirins have extensively been studied in vertebrates and many invertebrates; however, there is no report so far on lepidopteran insects. In the present study, we identified and characterized a novel Akirin from the silkworm, Bombyx mori (designated as BmAkirin), and explored its potential roles in innate immunity. The expression analysis revealed the unequal mRNA levels of BmAkirin in all the tested tissues; however, the gene's transcription level was highest in testis, followed by ovaries and hemocytes. It also had significant expression levels at the early stages of embryonic development. Expression of BmAkirin in fat bodies and hemocytes exhibited an increase in various degrees when challenged with virus, fungus, Gram-negative bacteria, and Gram-positive bacteria. Immunofluorescence analysis showed BmAkirin protein was prominently localized in the nucleus. Knockdown of BmAkirin strongly reduced the expression of AMPs and decreased the survival ability of larva upon immune stimulation. Moreover, the bacterial clearance ability of larvae was also decreased following the depletion of BmAkirin. Collectively, our results demonstrate that BmAkirin plays an indispensable role in the innate immunity of Bombyx mori (B. mori) by positively modulating AMPs expression in vivo.

Effect of thermal manipulation during embryogenesis on the promoter methylation and expression of myogenesis-related genes in duck skeletal muscle

Avian embryos are an ideal system to investigate the effect of incubation temperature on embryonic development, but the characteristics and mechanisms of temperature effects on poultry embryonic myogenesis are unclear. In this study, we investigated the effect of increasing the incubation temperature by 1 °C on the expression of nine myogenesis-related genes in ducks and then explored the correlation between the alteration of promoter methylation and the expression of two of the nine genes under thermal manipulation (TM). The qRT-PCR results showed that TM during embryonic days (ED) 1-10 promoted (P < 0.05) the expression of genes in breast muscle (PAX3, PAX7, MYOG, MCK, SIX1, TNNC1) and leg muscle (MYOD, MYOG, MYF5, MCK, AKIRIN2, TNNC1). TM during ED10-20 promoted the expression of PAX3, MYF5 and MCK and inhibited AKIRIN2 expression in breast muscle (P < 0.05); however, it inhibited the expression of PAX3, PAX7, MYOD, MYOG, MYF5, SIX1, AKIRIN2 and TNNC1 and promoted MCK expression in leg muscle (P < 0.05). TM during ED20-27 inhibited the expression of genes in breast muscle (PAX7) and leg muscle (MYOD, MYOG, MYF5, TNNC1) and promoted MCK expression in breast and leg muscle (P < 0.05). Furthermore, with the Sequenom MassARRAY platform, it was observed that the average methylation level of AKIRIN2 (ED10) and TNNC1 (ED20) in leg muscle decreased (P < 0.05) after TM. Notably, we found significant (P < 0.05) inverse correlations between the methylation and mRNA levels of AKIRIN2 under TM during ED1-10 (r = - 0.969) and ED10-20 (r = - 0.805). Taken together, TM during ED1-10 was more favorable for improving duck myogenesis-related gene expression than TM during ED10-20 and ED20-27. TM during duck embryogenesis seemed to have a greater effect on the development of leg muscle than breast muscle and might alter AKIRIN2 expression by changing its promoter methylation status. These findings may be helpful to understand temperature effects on the muscle development of avian embryos and to explore the role of epigenetic regulation during this process.

Functional Evolution of Subolesin/Akirin

The Subolesin/Akirin constitutes a good model for the study of functional evolution because these proteins have been conserved throughout the metazoan and play a role in the regulation of different biological processes. Here, we investigated the evolutionary history of Subolesin/Akirin with recent results on their structure, protein-protein interactions and function in different species to provide insights into the functional evolution of these regulatory proteins, and their potential as vaccine antigens for the control of ectoparasite infestations and pathogen infection. The results suggest that Subolesin/Akirin evolved conserving not only its sequence and structure, but also its function and role in cell interactome and regulome in response to pathogen infection and other biological processes. This functional conservation provides a platform for further characterization of the function of these regulatory proteins, and how their evolution can meet species-specific demands. Furthermore, the conserved functional evolution of Subolesin/Akirin correlates with the protective capacity shown by these proteins in vaccine formulations for the control of different arthropod and pathogen species. These results encourage further research to characterize the structure and function of these proteins, and to develop new vaccine formulations by combining Subolesin/Akirin with interacting proteins for the control of multiple ectoparasite infestations and pathogen infection.

Effects of Active Immunization Against Akirin2 on Muscle Fiber-type Composition in Pigs

The objective of this study was to investigate effects of active immunization against Akirin2 on muscle fiber-type composition in pigs. Here we showed that the titer of Akirin2 antibody in pigs immunized with porcine Akirin2 (pAkirin2) was significantly increased. Active immunization against pAkirin2 decreased succinic dehydrogenase and malate dehydrogenase activities and increased lactate dehydrogenase activity in the longissimus dorsi muscle of pigs. Active immunization against pAkirin2 significantly decreased MyHC I and MyHC IIa mRNA expressions and MyHC I protein expression and increased mRNA expressions of MyHC IIb as well as protein expressions of MyHC IIb and fast-MyHC. mRNA expressions of nuclear factors of activated T cells c1 (NFATc1), transcriptional coactivator PPARγ coactivator-1α, myocyte enhancer factor 2C, and modulatory calcineurin interacting protein 1 exon 4 isform were also notably decreased by active immunization against pAkirin2. Together, our data imply that active immunization against pAkirin2 may result in a slow to fast fiber-type shift in pigs, and which may be mediated by suppression of the calcineurin/NFATc1 signaling pathway.

Akirin2 regulates proliferation and differentiation of porcine skeletal muscle satellite cells via ERK1/2 and NFATc1 signaling pathways

Akirin2, a novel nuclear factor, plays an important role in myogenesis. To investigate the role of Akirin2 in proliferation and differentiation of porcine skeletal muscle satellite cells, Akirin2 overexpression and Akirin2 silence technologies were employed. Our results showed that overexpression of Akirin2 markedly enhanced the proliferation and differentiation of porcine skeletal muscle satellite cells, whereas silencing of Akirin2 got the opposite results. Furthermore, our results showed that Akirin2 affected proliferation and differentiation of porcine skeletal muscle satellite cells through extracellular-signal regulated kinase-1/2 (ERK1/2) and NFATc1 signaling pathways. These results indicate that Akirin2 can effectively promote skeletal muscle satellite cells proliferation and differentiation, acting through ERK1/2- and NFATc1-dependent mechanisms.

The Crosstalk between HDPSCs and HUCMSCs on Proliferation and Osteogenic Genes Expression in Coculture System

Objectives: The present study established a non-contact coculture system in vitro, aiming to investigate the crosstalk between human dental pulp stem cells (hDPSCs) and human umbilical cord mesenchymal stem cells (hUCMSCs) on proliferation activity and osteogenic genes expression through paracrine. Materials and methods: The stemness of hDPSCs and hUCMSCs were identified by flow cytometric analysis and multipotential differentiation assays. With the help of transwell inserts, the non-contact coculture system in vitro was established between hDPSCs and hUCMSCs. EdU labeling analysis and Western Blot were used to detect the proliferation activity. The mRNA and protein levels of osteogenic genes were evaluated by RT-PCR and Western Blot. The expression of elements in Akt/mTOR signaling pathway were detected by Western Blot. Results: Both hDPSCs and hUCMSCs were positive to MSCs specific surface markers and had multi-differentiation potential. The proportion of EdU-positive cells increased and the expression of CDK6 and CYCLIN A were up-regulated in cocultured hDPSCs. Both prior coculture and persistent coculture improved mRNA and protein levels of osteogenic genes in hDPSCs. While in cocultured hUCMSCs, no statistical differences were observed on proliferation and osteogenesis. The phosphorylation of Akt and mTOR was up-regulated in cocultured hDPSCs. Conclusions: The crosstalk between hDPSCs and hUCMSCs in coculture system increased the proliferation activity and enhanced osteogenic genes expression in hDPSCs. Akt/mTOR signaling pathway might take part in the enhancing effects in both cell proliferation and gene expression.