GPAT Gene Silencing in Muscle Reduces Diacylglycerols Content and Improves Insulin Action in Diet-Induced Insulin Resistance

Kojta, Iwona; Zabielski, Piotr; Roszczyc-Owsiejczuk, Kamila; Imierska, Monika; Sokołowska, Emilia

doi:10.3390/ijms21197369

Cited by 12 publications

(14 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Decreased insulin sensitivity was manifested by increased fasting glucose and insulin levels, impaired glucose tolerance, decreased insulin sensitivity, and increased HOMA-IR. The same effects of consuming a high-fat diet have also been reported in other studies [ 23 , 36 , 37 , 38 , 39 , 40 , 41 ]. In addition, it has also been confirmed that the HFD diet leads to an increase in total free fatty acids in plasma.…”

Section: Discussionsupporting

confidence: 84%

Serine Palmitoyltransferase Gene Silencing Prevents Ceramide Accumulation and Insulin Resistance in Muscles in Mice Fed a High-Fat Diet

Imierska

Roszczyc-Owsiejczuk

Sokołowska

et al. 2022

Cells

Self Cite

View full text Add to dashboard Cite

Skeletal muscles account for ~80% of insulin-stimulated glucose uptake and play a key role in lipid metabolism. Consumption of a high-fat diet (HFD) contributes to metabolic changes in muscles, including the development of insulin resistance. The studies carried out to date indicate that the accumulation of biologically active lipids, such as long-chain acyl-CoA, diacylglycerols and ceramides, play an important role in the development of insulin resistance in skeletal muscles. Unfortunately, it has not yet been clarified which of these lipid groups plays the dominant role in inducing these disorders. In order to explore this topic further, we locally silenced the gene encoding serine palmitoyltransferase (SPT) in the gastrocnemius muscle of animals with HFD-induced insulin resistance. This enzyme is primarily responsible for the first step of de novo ceramide biosynthesis. The obtained results confirm that the HFD induces the development of whole-body insulin resistance, which results in inhibition of the insulin pathway. This is associated with an increased level of biologically active lipids in the muscles. Our results also demonstrate that silencing the SPT gene with the shRNA plasmid reduces the accumulation of ceramides in gastrocnemius muscle, which, in turn, boosts the activity of the insulin signaling pathway. Furthermore, inhibition of ceramide synthesis does not significantly affect the content of other lipids, which suggests the leading role of ceramide in the lipid-related induction of skeletal muscle insulin resistance.

show abstract

Section: Discussionsupporting

confidence: 84%

Serine Palmitoyltransferase Gene Silencing Prevents Ceramide Accumulation and Insulin Resistance in Muscles in Mice Fed a High-Fat Diet

Imierska

Roszczyc-Owsiejczuk

Sokołowska

et al. 2022

Cells

Self Cite

View full text Add to dashboard Cite

show abstract

“…SPT is considered as a key enzyme regulating sphingolipid levels in cells, and regulation of SPT may prevent the harmful accumulation of ceramide ( Hanada 2003 ). GPAT play an important role in the de novo synthesis of DAG ( Kojta et al, 2020 ). CPT-1A is responsible for the transfer of FA into mitochondria and is the key enzyme in the oxidation of FA ( Lundsgaard et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

“…Serine-palmitoyl transferase (SPT) is a heterodimer composed of two subunits, SPT long chain 1 (SPTLC1) and SPT long chain 2 (SPTLC2), and is the rate-limiting enzyme for de novo ceramide synthesis. Glycerol-3-phosphate acyltransferases (GPAT) is the rate-limiting enzyme in the lipid anabolic pathway and is involved in the de novo synthesis of DAG ( Kojta et al, 2020 ). Carnitine palmitoyltransferase-1A (CPT-1A) is located in the inner membrane of cell mitochondria and is a key rate-limiting enzyme in the FAO.…”

Section: Introductionmentioning

confidence: 99%

Notoginsenoside R1 Ameliorates Cardiac Lipotoxicity Through AMPK Signaling Pathway

et al. 2022

View full text Add to dashboard Cite

Aims: Cardiac lipotoxicity is the common consequence of lipid metabolism disorders in cardiomyocytes during development of heart failure (HF). Adenosine 5′monophosphate-activated protein kinase (AMPK) acts as an energy sensor and has a beneficial effect in reducing lipotoxicity. Notoginsenoside R1 (NGR1) is extracted from the traditional Chinese medicine Panax notoginseng (Burkill) F.H.Chen (P. notoginseng) and has definite cardioprotective effects. However, whether NGR1 can attenuate HF by mitigating lipotoxicity has not been elucidated yet. This study aimed to explore whether NGR1 plays a protective role against HF by ameliorating cardiac lipotoxicity via the AMPK pathway.Methods: In this study, HF mice model was established by left anterior descending (LAD) ligation. palmitic acid (PA) stimulated H9C2 cell model was applied to clarify the effects and potential mechanism of NGR1 on lipotoxicity. In vivo, NGR1 (7.14 mg/kg/days) and positive drug (simvastatin: 2.9 mg/kg/days) were orally administered for 14 days. Echocardiography was applied to assess heart functions. Lipid levels were measured by Enzyme-linked immunosorbent assay (ELISA) and key proteins in the AMPK pathway were detected by western blots. In vitro, NGR1 (40 μmol/L) or Compound C (an inhibitor of AMPK, 10 μmol/L) was co-cultured with PA stimulation for 24 h in H9C2 cells. CCK-8 assay was used to detect cell viability. Key lipotoxicity-related proteins were detected by western blots and the LipidTOX™ neutral lipid stains were used to assess lipid accumulation. In addition, Apoptosis was assessed by Hoechst/PI staining.Results: NGR1 could significantly improve the cardiac function and myocardial injury in mice with HF and up-regulate the expression of p-AMPK. Impressively, NGR1 inhibited the synthesis of diacylglycerol (DAG) and ceramide and promoted fatty acid oxidation (FAO) in vivo. Moreover, NGR1 significantly promoted expression of CPT-1A, the key enzyme in FAO pathway, and down-regulated the expression of GPAT and SPT, which were the key enzymes catalyzing production of DAG and ceramide. In vitro experiments showed that NGR1 could significantly attenuate lipid accumulation in PA-induced H9C2 cells and the Hoechst/PI staining results showed that NGR1 ameliorated lipotoxicity-induced apoptosis in PA-stimulated H9C2 cell model. Furthermore, co-treatment with inhibitor of AMPK abrogated the protective effects of NGR1. The regulative effects of NGR1 on lipid metabolism were also reversed by AMPK inhibitor.Conclusion: NGR1 could significantly improve the heart function of mice with HF and reduce cardiac lipotoxicity. The cardio-protective effects of NGR1 are mediated by the activation of AMPK pathway.

show abstract

“…Skeletal muscle glucose uptake under insulin stimulation was measured with the intravenous bolus of 2-deoxy-[1,2-3H (N)]-D-glucose, as described earlier [ 28 ]. Animals received radiolabeled glucose injection through lateral tail vein 20 min prior to euthanasia (12 µCi/25 g fat-free mass, total volume approx.…”

Section: Methodsmentioning

confidence: 99%

CerS1 but Not CerS5 Gene Silencing, Improves Insulin Sensitivity and Glucose Uptake in Skeletal Muscle

Błachnio-Zabielska

Roszczyc-Owsiejczuk

Imierska

et al. 2022

Cells

Self Cite

View full text Add to dashboard Cite

Skeletal muscle is perceived as a major tissue in glucose and lipid metabolism. High fat diet (HFD) lead to the accumulation of intramuscular lipids, including: long chain acyl-CoA, diacylglycerols, and ceramides. Ceramides are considered to be one of the most important lipid groups in the generation of skeletal muscle insulin resistance. So far, it has not been clearly established whether all ceramides adversely affect the functioning of the insulin pathway, or whether there are certain ceramide species that play a pivotal role in the induction of insulin resistance. Therefore, we designed a study in which the expression of CerS1 and CerS5 genes responsible for the synthesis of C18:0-Cer and C16:0-Cer, respectively, was locally silenced in the gastrocnemius muscle of HFD-fed mice through in vivo electroporation-mediated shRNA plasmids. Our study indicates that HFD feeding induced both, the systemic and skeletal muscle insulin resistance, which was accompanied by an increase in the intramuscular lipid levels, decreased activation of the insulin pathway and, consequently, a decrease in the skeletal muscle glucose uptake. CerS1 silencing leads to a reduction in C18:0-Cer content, with a subsequent increase in the activity of the insulin pathway, and an improvement in skeletal muscle glucose uptake. Such effects were not visible in case of CerS5 silencing, which indicates that the accumulation of C18:0-Cer plays a decisive role in the induction of skeletal muscle insulin resistance.

show abstract

GPAT Gene Silencing in Muscle Reduces Diacylglycerols Content and Improves Insulin Action in Diet-Induced Insulin Resistance

Cited by 12 publications

References 45 publications

Serine Palmitoyltransferase Gene Silencing Prevents Ceramide Accumulation and Insulin Resistance in Muscles in Mice Fed a High-Fat Diet

Serine Palmitoyltransferase Gene Silencing Prevents Ceramide Accumulation and Insulin Resistance in Muscles in Mice Fed a High-Fat Diet

Notoginsenoside R1 Ameliorates Cardiac Lipotoxicity Through AMPK Signaling Pathway

CerS1 but Not CerS5 Gene Silencing, Improves Insulin Sensitivity and Glucose Uptake in Skeletal Muscle

Contact Info

Product

Resources

About