Pim1 kinase positively regulates myoblast behaviors and skeletal muscle regeneration

Transcriptomic Profiling of Meat Quality Traits of Skeletal Muscles of the Chinese Indigenous Huai Pig and Duroc Pig

The Huai pig is a well-known indigenous pig breed in China. The main advantages of Huai pigs over Western commercial pig breeds include a high intramuscular fat (IMF) content and good meat quality. There are significant differences in the meat quality traits of the same muscle part or different muscle parts of the same variety. To investigate the potential genetic mechanism underlying the meat quality differences in different pig breeds or muscle groups, longissimus dorsi (LD), psoas major (PM), and biceps femoris (BF) muscle tissues were collected from two pig breeds (Huai and Duroc). There were significant differences in meat quality traits and amino acid content. We assessed the muscle transcriptomic profiles using high-throughput RNA sequencing. The IMF content in the LD, PM, and BF muscles of Huai pigs was significantly higher than that in Duroc pigs (p < 0.05). Similarly, the content of flavor amino acids in the three muscle groups was significantly higher in Huai pigs than that in Duroc pigs (p < 0.05). We identified 175, 110, and 86 differentially expressed genes (DEGs) between the LD, PM, and BF muscles of the Huai and Duroc pigs, respectively. The DEGs of the different pig breeds and muscle regions were significantly enriched in the biological processes and signaling pathways related to muscle fiber type, IMF deposition, lipid metabolism, PPAR signaling, cAMP signaling, amino acid metabolism, and ECM-receptor interaction. Our findings might help improve pork yield by using the obtained DEGs for marker-assisted selection and providing a theoretical reference for evaluating and improving pork quality.

Serum-Circulating microRNAs in Sporadic Inclusion Body Myositis

BACKGROUND

Sporadic inclusion body myositis (s-IBM) represents a unique disease within idiopathic inflammatory myopathies with a dual myodegenerative-autoimmune physiopathology and a lack of an efficacious treatment. Circulating miRNA expression could expand our knowledge of s-IBM patho-mechanisms and provide new potential disease biomarkers. To evaluate the expression of selected pre-amplified miRNAs in the serum of s-IBM patients compared to those of a sex- and age-matched healthy control group, we enrolled 14 consecutive s-IBM patients and 8 sex- and age-matched healthy controls. By using two different normalization approaches, we found one downregulated and three upregulated miRNAs. hsa-miR-192-5p was significantly downregulated, while hsa-miR-372-3p was found to be upregulated more in the s-IBM patients compared to the level of the controls. The other two miRNAs had a very low expression levels (raw Ct data > 29). hsa-miR-192-5p and hsa-miR-372-3p were found to be significantly dysregulated in the serum of s-IBM patients. These miRNAs are involved in differentiation and regeneration processes, thus possibly reflecting pathological mechanisms in s-IBM muscles and potentially representing disease biomarkers.

Effects of an exogenous ketone ester using multi-omics in skeletal muscle of aging C57BL/6J male mice

Exogenous ketone ester supplementation provides a means to increase circulating ketone concentrations without the dietary challenges imposed by ketogenic diets. Our group has shown that oral R,S-1,3, butanediol diacetoacetate (BD-AcAc2) consumption results in body weight loss or maintenance with moderate increases in circulating ketones. We have previously shown a diet consisting of 25% BD-AcAc2 can maintain lean body mass (LBM) and induce fat mass (FM) loss in young, healthy male mice, but the underlying mechanisms are still unknown. Therefore, the purpose of this study was to determine if a diet consisting of 25% BD-AcAc2 (ketone ester, KE) would alter body composition, transcriptional regulation, the proteome, and the lipidome of skeletal muscle in aged mice. We hypothesized that the KE group would remain weight stable with improvements in body composition compared to controls, resulting in a healthy aging phenotype. Male C57BL/6J mice (n = 16) were purchased from Jackson Laboratories at 72 weeks of age. After 1 week of acclimation, mice were weighed and randomly assigned to one of two groups (n = 8 per group): control (CON) or KE. A significant group by time interaction was observed for body weight (P &lt; 0.001), with KE fed mice weighing significantly less than CON. FM increased over time in the control group but was unchanged in the KE group. Furthermore, LBM was not different between CON and KE mice despite KE mice weighing less than CON mice. Transcriptional analysis of skeletal muscle identified 6 genes that were significantly higher and 21 genes that were significantly lower in the KE group compared to CON. Lipidomic analysis of skeletal muscle identified no differences between groups for any lipid species, except for fatty acyl chains in triacylglycerol which was 46% lower in the KE group. Proteomics analysis identified 44 proteins that were different between groups, of which 11 were lower and 33 were higher in the KE group compared to CON. In conclusion, 72-week-old male mice consuming the exogenous KE, BD-AcAc2, had lower age-related gains in body weight and FM compared to CON mice. Furthermore, transcriptional and proteomics data suggest a signature in skeletal muscle of KE-treated mice consistent with markers of improved skeletal muscle regeneration, improved electron transport chain utilization, and increased insulin sensitivity.

Exercise-induced signaling pathways to counteracting cardiac apoptotic processes

Cardiovascular diseases are the most common cause of death in the world. One of the major causes of cardiac death is excessive apoptosis. However, multiple pathways through moderate exercise can reduce myocardial apoptosis. After moderate exercise, the expression of anti-apoptotic proteins such as IGF-1, IGF-1R, p-PI3K, p-Akt, ERK-1/2, SIRT3, PGC-1α, and Bcl-2 increases in the heart. While apoptotic proteins such as PTEN, PHLPP-1, GSK-3, JNK, P38MAPK, and FOXO are reduced in the heart. Exercise-induced mechanical stress activates the β and α5 integrins and subsequently, focal adhesion kinase phosphorylation activates the Akt/mTORC1 and ERK-1/2 pathways, leading to an anti-apoptotic response. One of the reasons for the decrease in exercise-induced apoptosis is the decrease in Fas-ligand protein, Fas-death receptor, TNF-α receptor, Fas-associated death domain (FADD), caspase-8, and caspase-3. In addition, after exercise mitochondrial-dependent apoptotic factors such as Bid, t-Bid, Bad, p-Bad, Bak, cytochrome c, and caspase-9 are reduced. These changes lead to a reduction in oxidative damage, a reduction in infarct size, a reduction in cardiac apoptosis, and an increase in myocardial function. After exercising in the heart, the levels of RhoA, ROCK1, Rac1, and ROCK2 decrease, while the levels of PKCε, PKCδ, and PKCɑ are activated to regulate calcium and prevent mPTP perforation. Exercise has an anti-apoptotic effect on heart failure by increasing the PKA-Akt-eNOS and FSTL1-USP10-Notch1 pathways, reducing the negative effects of CaMKIIδ, and increasing the calcineurin/NFAT pathway. Exercise plays a protective role in the heart by increasing HSP20, HSP27, HSP40, HSP70, HSP72, and HSP90 along with increasing JAK2 and STAT3 phosphorylation. However, research on exercise and factors such as Pim-1, Notch, and FAK in cardiac apoptosis is scarce, so further research is needed. Future research is recommended to discover more anti-apoptotic pathways. It is also recommended to study the synergistic effect of exercise with gene therapy, dietary supplements, and cell therapy for future research.

A systematic review on active sites and functions of PIM-1 protein

The Proviral Integration of Molony murine leukemia virus (PIM)-1 protein contributes to the solid cancers and hematologic malignancies, cell growth, proliferation, differentiation, migration, and other life activities. Many studies have related these functions to its molecular structure, subcellular localization and expression level. However, recognition of specific active sites and their effects on the activity of this constitutively active kinase is still a challenge. Based on the close relationship between its molecular structure and functional activity, this review covers the specific residues involved in the binding of ATP and different substrates in its catalytic domain. This review then elaborates on the relevant changes in protein conformation and cell functions after PIM-1 binds to different substrates. Therefore, this intensive study can improve the understanding of PIM-1-regulated signaling pathways by facilitating the discovery of its potential phosphorylation substrates.

Pim1 knockout alleviates sarcopenia in aging mice via reducing adipogenic differentiation of PDGFRα+ mesenchymal progenitors

BACKGROUND

Sarcopenia widely exists in elderly people and triggers numerous age-related events. The essential pathologic change lies in the increased intramuscular adipose tissue after aging with no exception to non-obese objects. Pim1 appears to be associated with adipogenic differentiation in recent studies, inspiring us to explore whether it regulates adipogenesis in aging muscles and affects sarcopenia.

METHODS

Wild-type and Pim1 knockout C57/BL6J mice were randomized into young and old groups. Histo-pathological and molecular biological methods were applied to assess the intramuscular adipose tissue content, the atrophy and regeneration, and the expressions of Pim1 and adipogenic transcription factors. PDGFRα+ mesenchymal progenitors were separated and their replicative aging model were established. Different time of adipogenic induction and different amounts of Pim1 inhibitor were applied, after which the adipogenic potency were evaluated. The expressions of Pim1 and adipogenic transcription factors were measured through western blotting.

RESULTS

The aging mice demonstrated decreased forelimb grip strength (P = 0.0003), hanging impulse (P < 0.0001), exhaustive running time (P < 0.0001), tetanic force (P = 0.0298), lean mass (P = 0.0008), and percentage of gastrocnemius weight in body weight (P < 0.0001), which were improved by Pim1 knockout (P = 0.0015, P = 0.0222, P < 0.0001, P = 0.0444, P = 0.0004, and P = 0.0003, respectively). To elucidate the mechanisms, analyses showed that Pim1 knockout decreased the fat mass (P = 0.0005) and reduced the intramuscular adipose tissue content (P = 0.0008) by inhibiting the C/EBPδ pathway (P = 0.0067) in aging mice, resulting in increased cross-sectional area of all and fast muscle fibres (P = 0.0017 and 0.0024 respectively), decreased levels of MuRF 1 and atrogin 1 (P = 0.0001 and 0.0329 respectively), and decreased content of Pax7 at the basal state (P = 0.0055). In vitro, senescent PDGFRα+ mesenchymal progenitors showed significantly increased the intracellular adipose tissue content (OD510) compared with young cells after 6 days of adipogenic induction (P < 0.0001). The Pim1 expression was elevated during adipogenic differentiation, and Pim1 inhibition significantly reduced the OD510 in senescent cells (P = 0.0040) by inhibiting the C/EBPδ pathway (P = 0.0047).

CONCLUSIONS

Pim1 knockout exerted protective effects in sarcopenia by inhibiting the adipogenic differentiation of PDGFRα+ mesenchymal progenitors induced by C/EBPδ activation and thus reducing the intramuscular adipose tissue content in aging mice. These results provide a potential target for the treatment of sarcopenia.

Negative Regulation of Erythroid Differentiation via the CBX8-TRIM28 Axis

Although the mechanism of chronic myeloid leukemia (CML) initiation through BCR/ABL oncogene has been well characterized, CML cell differentiation into erythroid lineage cells remains poorly understood. Using CRISPR-Cas9 screening, we identify Chromobox 8 (CBX8) as a negative regulator of K562 cell differentiation into erythrocytes. CBX8 is degraded via proteasomal pathway during K562 cell differentiation, which activates the expression of erythroid differentiation-related genes that are repressed by CBX8 in the complex of PRC1. During the differentiation process, the serine/threonine-protein kinase PIM1 phosphorylates serine 196 on CBX8, which contributes to CBX8 reduction. When CD235A expression levels are analyzed, the result reveals that the knockdown of PIM1 inhibits K562 cell differentiation. We also identify TRIM28 as another interaction partner of CBX8 by proteomic analysis. Intriguingly, TRIM28 maintains protein stability of CBX8 and TRIM28 loss significantly induces proteasomal degradation of CBX8, resulting in an acceleration of erythroid differentiation. Here, we demonstrate the involvement of the CBX8-TRIM28 axis during CML cell differentiation, suggesting that CBX8 and TRIM28 are promising novel targets for CML research.

Magnesium supplementation enhances mTOR signalling to facilitate myogenic differentiation and improve aged muscle performance

Magnesium (Mg²⁺), as an essential mineral, supports and sustains the health and activity of the organs of the human body. Despite some clinical evidence on the association of Mg²⁺ deficiency with muscle regeneration dysfunction and sarcopenia in older-aged individuals, there is no consensus on the action mode and molecular mechanism by which Mg²⁺ influences aged muscle size and function. Here, we identified the appropriate Mg²⁺ environment that promotes the myogenic differentiation and myotube hypertrophy in both C2C12 myoblast and primary aged muscle stem cell (MuSC). Through animal experiments, we demonstrated that Mg²⁺ supplementation in aged mice significantly promotes muscle regeneration and conserves muscle mass and strength. Mechanistically, Mg²⁺ stimulation activated the mammalian target of rapamycin (mTOR) signalling, inducing the myogenic differentiation and protein synthesis, which consequently offers protections against the age-related decline in muscle regenerative potential and muscle mass. These findings collectively provide a promising therapeutic strategy for MuSC dysfunction and sarcopenia through Mg²⁺ supplementation in the elderly.

Detecting differentially methylated regions with multiple distinct associations

Aim: We evaluated five methods for detecting differentially methylated regions (DMRs): DMRcate, comb-p, seqlm, GlobalP and dmrff. Materials & methods: We used a simulation study and real data analysis to evaluate performance. Additionally, we evaluated the use of an ancestry-matched reference cohort to estimate correlations between CpG sites in cord blood. Results: Several methods had inflated Type I error, which increased at more stringent significant levels. In power simulations with 1-2 causal CpG sites with the same direction of effect, dmrff was consistently among the most powerful methods. Conclusion: This study illustrates the need for more thorough simulation studies when evaluating novel methods. More work must be done to develop methods with well-controlled Type I error that do not require individual-level data.

Analysis of Key Genes Regulating the Warburg Effect in Patients with Gastrointestinal Cancers and Selective Inhibition of This Metabolic Pathway in Liver Cancer Cells

Objective

The Warburg effect, also known as aerobic glycolysis, plays a dominant role in the development of gastrointestinal (GI) cancers. In this study, we analyzed the expression of key genes involved in the Warburg effect in GI cancers and investigated the effect of suppressing the Warburg effect in vitro in liver cancer cell lines.

Methods

The Cancer Genome Atlas (TCGA) RNA-Seq data were used to determine gene expression levels, which were analyzed with GraphPad Prism 7.00. Genetic alterations were queried with cBioPortal. The influence of the Warburg effect on liver cancer cell viability, migration and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity was determined by means of MTT, transwell and GAPDH activity assays.

Results

The levels of expression of genes associated with the Warburg effect were increased in tumors. To our knowledge, this is the first report of upregulated expression of CUEDC2, HMGB2, PFKFB4, PFKP and SIX1 in liver cancer. Clinically, overexpression of these genes was associated with significantly worse overall survival of liver cancer patients. In vitro, selective inhibition of GADPH suppressed the growth and metastasis of Huh-7, Bel7404 and Hep3B hepatocellular carcinoma cell lines.

Conclusion

The Warburg effect may play an important role in GI cancers, especially in liver cancer.