Hormone-sensitive lipase deficiency affects the expression of SR-BI, LDLr, and ABCA1 receptors/transporters involved in cellular cholesterol uptake and efflux and disturbs fertility in mouse testis

A bioinformatic approach to characterize the vitellogenin receptor and the low density lipoprotein receptor superfamily in the newt Cynops orientalis

The Low Density Lipoprotein receptors (LDLRs) gene family includes 15 receptors: very low-density lipoprotein receptor (VLDLR), LDLR, Sorting-related receptor with A-type repeats (SORLA), and 12 LDL receptor-related proteins (LRPs): LRP1, LRP1B, LRP2, LRP3, LRP4, LRP5, LRP6, LRP8, LRP10, LRP11, LRP12, LRP13. Most of these are involved in the transduction of key signals during embryonic development and in the regulation of cholesterol homeostasis. In oviparous animals, the VLDL receptor is also known as VTGR since it facilitates the uptake of vitellogenin in ovary. In tetrapods, information concerning genes encoding these proteins is limited to a few taxa. Here, we report the characterization of VTGR in the amphibian Cynops orientalis. The secondary structure analyses and the expression profiles obtained from hepatic and gonadal tissues of C. orientalis supported the role of VTGR as vitellogenin oocyte membrane receptor in this species. Moreover, to get a holistic view of the evolutionary history of this gene superfamily, we extended our investigation to all 15 genes belonging to the LDLR superfamily analyzing through a phylogenetic analysis a total of 161 sequences belonging to 11 genera of vertebrates. The position of LRP8 in the tree and its expression findings in C. orientalis ovary allowed us to suggest that other proteins of the LDLR superfamily could act as receptors during vitellogenesis.

SEC14L2 regulates the transport of cholesterol in non-small cell lung cancer through SCARB1

BACKGROUND

Inhibiting cholesterol metabolism has shown great potential in non-small cell lung cancer (NSCLC). However, the regulatory mechanism of the lipid metabolism key factor Sect. 14-like lipid binding 2 (SEC14L2) in NSCLC remains unclear. This study investigates the effects of differentially expressed genes related to cholesterol metabolism on the development of NSCLC.

METHODS

Cox regression and survival analysis were performed to screen cholesterol metabolism-related genes and predict survival prognosis in NSCLC patients. The proliferation and migration of NSCLC cells were assessed by CCK-8, EdU, colony formation and wound-healing assay. Cholesterol depletion and rescue trials were used to evaluate the effect of SEC14L2 on cholesterol transport in NSCLC cells. IF and Co-IP were used to analyze the targeting relationship between SEC14L2 and scavenger receptor class B member 1 (SCARB1).

RESULTS

SEC14L2 was a key gene related to prognosis in NSCLC patients and was highly expressed in A549 and Calu-1 cells. Subsequent studies demonstrated that knockdown of SEC14L2 significantly reduced the proliferation and migration of NSCLC cells, resulting in inhibited tumor growth. Furthermore, both in vitro and in vivo experiments indicated that SEC14L2 regulated cholesterol uptake. Silencing SEC14L2 partially counteracted the promotion of cholesterol content by MβCD-chol in A549 and Calu-1 cells. We then verified that there was a protein interaction between SEC14L2 and SCARB1.

CONCLUSION

SEC14L2 promoted cholesterol uptake in NSCLC cells by up-regulating SCARB1 expression, thereby promoting NSCLC development.

Extra-virgin olive oil ameliorates high-fat diet-induced seminal and testicular disorders by modulating the cholesterol pathway

BACKGROUND

Rabbits are sensitive to dietary cholesterol and rapidly develop hypercholesterolemia, leading to prominent subfertility. Sterol regulatory element-binding protein isoform 2 drives the intracellular cholesterol pathway in many tissues, including the testicles. Its abnormal regulation could be the mainly responsible for the failure of suppressing cholesterol synthesis in a cholesterol-enriched environment, ultimately leading to testicular and seminal alterations. However, extra-virgin olive oil consumption has beneficial properties that promote lowering of cholesterol levels, including the recovery of seminal parameters altered under a high-fat diet.

OBJECTIVES

Our goal was to investigate the effects of high-fat diet supplementation with extra-virgin olive oil at the molecular level on rabbit testes, by analyzing sterol regulatory element-binding protein isoform 2 protein and its corresponding downstream effectors.

MATERIALS AND METHODS

During 12 months, male rabbits were fed a control diet, high-fat diet, or 6-month high-fat diet followed by 6-month high-fat diet plus extra-virgin olive oil. Serum lipids, testosterone levels, bodyweight, and seminal parameters were tested. The mRNA and protein levels of sterol regulatory element-binding protein isoform 2, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, and low-density lipoprotein receptor were determined by semi-quantitative polymerase chain reaction and Western blotting techniques. The expression pattern of sterol regulatory element-binding protein isoform 2 protein in the rabbit testicles was studied by indirect immunofluorescence. In addition, testicular cholesterol was detected and quantified by filipin staining and gas chromatography.

RESULTS

The data showed that the addition of extra-virgin olive oil to high-fat diet reduced testicular cholesterol levels and recovered the expression of sterol regulatory element-binding protein isoform 2, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, and low-density lipoprotein receptor initially altered by the high-fat diet.

DISCUSSION AND CONCLUSIONS

The combination of high-fat diet with extra-virgin olive oil encourages testicular recovery by modifying the expression of the enzymes related to intracellular cholesterol management.

LDLR heterozygous deletion reduces hamster testicular cholesterol toxicity via AMPK/Sirt1/PGC-1α pathway

Cholesterol is an important part of the human diet. The relationship and molecular mechanisms between intracellular cholesterol and male infertility are unclear. The purpose of this study was to evaluate the role of low-density lipoprotein receptor (LDLR) in male infertility. Both wild-type (WT) and LDLR heterozygous deletion (LDLR+/-) male Golden Syrian hamsters were fed either a high-fat diet (HFD) or a normal diet (ND). Plasma biochemistry, serum hormone, testicular histopathology, mRNA and protein expression of AMPK/Sirt1/PGC-1α in both testicular tissue and isolated Leydig cells (LCs) were measured. Compared with the ND animals, the WT HFD hamsters developed dyslipidemia at three weeks with lipid droplets deposited in LCs, testosterone decreased at four weeks (0.440 ± 0.264 ng/ml vs. 2.367 ± 1.236 ng/ml), the number of the Sertoli cells decreased (21.578 ± 2.934/one tubule vs. 25.733 ± 3.424/one tubule), the seminiferous epithelium became thinner (0.0813 ± 0.01729 mm vs. 0.0944 ± 0.0138 mm), testicular atrophy and AMPK/Sirt1/PGC-1α pathway downregulated at five weeks. All these changes persisted until the end of the study. LDLR+/- alleviated all of the above changes by downregulating the cellular influx of cholesterol induced by HFD except for higher hyperlipidemia. In summary, excessive intracellular cholesterol inactivates AMPK/Sirt1/PGC-1α pathway firstly in LCs and then in both Sertoli and spermatids. Cholesterol toxicity was LDLR dependent.

Paternal cadmium exposure affects testosterone synthesis by reducing the testicular cholesterol pool in offspring mice

Cadmium（Cd） is a heavy metal that is harmful to human health. Early studies have shown that cadmium can damage testicular structure, affecting testosterone synthesis and spermatogenesis. However, the effect of paternal Cd exposure on the reproductive system of offspring remains unclear. In this study, male 8-week C57BL/6 J mice were used as research objects, and Cd was injected intraperitoneally every other day at a dose of 1 mg/kg for 5 weeks, after which the effect on the reproductive system of offspring male mice was studied. Our results showed that the body weight of the offspring male mice increased faster, with increases of the testicular and epididymis indices under Cd exposure. At the same time, the serum testosterone and free cholesterol decreased, total cholesterol increased, and the sperm concentration decreased. Further qRT-PCR and western blot analyses showed that the expressions of StAR, P450scc, 3β-HSD and 17β-HSD, which are related to testosterone synthesis, was significantly downregulated. Additionally, ATGL, LDLR and SR-BI, which are related to the intracellular cholesterol pool were downregulated, leading to the reduction of the cholesterol pool and the accumulation of lipid droplets. Oil red O and BODIPY staining revealed an increase in the abundance of lipid droplets in testicular tissue of newborn and adult mice. Prediction of tsRNA target genes in the sperm of parents and testicular transcriptome of newborn mice showed that the differentially expressed genes were associated with catabolism of fatty acids, cholesterol and ion channels, while the mitochondrial and lysosome functions of testicular tissue of adult offspring mice were decreased. Overall, our results suggest that paternal Cd exposure reduced the intracellular cholesterol pool of testicular of offspring, affected testosterone synthesis and reproductive system development.