Exploring scavenger receptor class F member 2 and the importance of scavenger receptor family in prediagnostic diseases.

Scavenger Receptor Class F Member 2 (SCARF2), also known as the Type F Scavenger Receptor Family gene, encodes for Scavenger Receptor Expressed by Endothelial Cells 2 (SREC-II). This protein is a crucial component of the scavenger receptor family and is vital in protecting mammals from infectious diseases. Although research on SCARF2 is limited, mutations in this protein have been shown to cause skeletal abnormalities in both SCARF2-deficient mice and individuals with Van den Ende-Gupta syndrome (VDEGS), which is also associated with SCARF2 mutations. In contrast, other scavenger receptors have demonstrated versatile responses and have been found to aid in pathogen elimination, lipid transportation, intracellular cargo transportation, and work in tandem with various coreceptors. This review will concentrate on recent progress in comprehending SCARF2 and the functions played by members of the Scavenger Receptor Family in pre-diagnostic diseases.

The potential inhibitory effect of ginsenoside Rh2 on mitophagy in UV-irradiated human dermal fibroblasts.

Background: In addition to its use as a health food, ginseng is used in cosmetics and shampoo because of its extensive health benefits. The ginsenoside, Rh2, is a component of ginseng that inhibits tumor cell proliferation and differentiation, promotes insulin secretion, improves insulin sensitivity, and shows antioxidant effects. Methods: The effects of Rh2 on cell survival, extracellular matrix (ECM) protein expression, and cell differentiation were examined. The antioxidant effects of Rh2 in UV-irradiated normal human dermal fibroblast (NHDF) cells were also examined. The effects of Rh2 on mitochondrial function, morphology, and mitophagy were investigated in UV-irradiated NHDF cells. Results: Rh2 treatment promoted the proliferation of NHDF cells. Additionally, Rh2 increased the expression levels of ECM proteins and growth-associated immediate-early genes in ultraviolet (UV)-irradiated NHDF cells. Rh2 also affected antioxidant protein expression and increased total antioxidant capacity. Furthermore, treatment with Rh2 ameliorated the changes in mitochondrial morphology, induced the recovery of mitochondrial function, and inhibited the initiation of mitophagy in UV-irradiated NHDF cells. Conclusion: Rh2 inhibits mitophagy and reinstates mitochondrial ATP production and membrane potential in NHDF cells damaged by UV exposure, leading to the recovery of ECM, cell proliferation, and antioxidant capacity.

Functional characteristics and research trends of PDE11A in human diseases (Review).

cAMP and cGMP are important secondary messengers involved in cell regulation and metabolism driven by the G protein­coupled receptor. cAMP is converted via adenylyl cyclase (AC) and activates protein kinase A to phosphorylate intracellular proteins that mediate specific responses. cAMP signaling serves a role at multiple steps in tumorigenesis. The level of cAMP is increased in association with cancer cell formation through activation of AC­stimulatory G protein by mutation. Phosphodiesterases (PDEs) hydrolyze cAMP and cGMP to AMP and GMP. PDEs are composed of 11 families, and each can hydrolyze cAMP and cGMP or both cAMP and cGMP. PDEs perform various roles depending on their location and expression site, and are involved in several diseases, including male erectile dysfunction, pulmonary hypertension, Alzheimer's disease and schizophrenia. PDE11A is the 11th member of the PDE family and is characterized by four splice variants with varying tissue expression and N­terminal regulatory regions. Among tissues, the expression of PDE11A was highest in the prostate, and it was also expressed in hepatic skeletal muscle, pituitary, pancreas and kidney. PDE11A is the first PDE associated with an adrenocortical tumor associated genetic condition. In several studies, three PDE11A mutations have been reported in patients with Cushing syndrome with primary pigmented nodular adrenocortical disease or isolated micronodular adrenocortical disease without other genetic defects. It has been reported that an increase in PDE11A expression affects the proliferation of glioblastoma and worsens patient prognosis. The present mini­review summarizes the location of PDE11A expression, the impact of structural differences and disease relevance.

Phosphodiesterase 11 A (PDE11A), a potential biomarker for glioblastoma.

Phosphodiesterase 11A (PDE11A), a 3',5'-cyclic nucleotide phosphodiesterase, is a key regulator of intracellular signaling that functions by degrading cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). However, the function of PDE11A in brain tumors is currently unclear. In this study, we found that PDE11A may be involved in glioblastoma development. The protein and mRNA levels of PDE11A were significantly higher in U87-MG, U251-MG and U343-MG glioblastoma cell lines. Gene expression analyses by deep-sequencing revealed that PDE11A mRNA levels were higher in U87-MG and U251-MG cells compared to other cells in the cerebral cortex. A comprehensive analysis of The Cancer Genome Atlas (TCGA) data revealed that PDE11A expression was also elevated in glioblastoma patients. Taken together, these data indicate that PDE11A expression was increased in glioblastoma cell lines and glioma patients, suggesting that PDE11A could be a putative diagnostic marker and therapeutic target for glioma.

Emerging role of LETM1/GRP78 axis in lung cancer.

The selective autophagy of damaged mitochondria is called mitophagy. Mitochondrial dysfunction, mitophagy, and apoptosis have been suggested to be interrelated in various human lung carcinomas. Leucine zipper EF-hand-containing transmembrane protein-1 (LETM1) was cloned in an attempt to identify candidate genes for Wolf-Hirschhorn syndrome. LETM1 plays a role in mitochondrial morphology, ion homeostasis, and cell viability. LETM1 has also been shown to be overexpressed in different human cancer tissues, including lung cancer. In the current study, we have provided clear evidence that LETM1 acts as an anchoring protein for the mitochondria-associated ER membrane (MAM). Fragmented mitochondria have been found in lung cancer cells with LETM1 overexpression. In addition, a reduction of mitochondrial membrane potential and significant accumulation of microtubule-associated protein 1 A/1B-light chain 3 punctate, which localizes with Red-Mito, was found in LETM1-overexpressed cells, suggesting that mitophagy is upregulated in these cells. Interestingly, glucose-regulated protein 78 kDa (GRP78; an ER chaperon protein) and glucose-regulated protein 75 kDa (GRP75) were posited to interact with LETM1 in the immunoprecipitated LETM1 of H460 cells. This interaction was enhanced in cells treated with carbonyl cyanide m-chlorophenylhydrazone, a chemical mitophagy inducer. Treatment of cells with honokiol (a GRP78 inhibitor) blocked LETM1-mediated mitophagy, and CRISPR/Cas9-mediated GRP75 knockout inhibited LETM1-induced autophagy. Thus, GRP78 interacts with LETM1. Taken together, these observations support the notion that the complex formation of LETM1/GRP75/GRP78 might be an important step in MAM formation and mitophagy, thus regulating mitochondrial quality control in lung cancer.

Scavenger receptor class F member 2 (SCARF2) as a novel therapeutic target in glioblastoma.

Scavenger receptor class F member 2 (SCARF2) is expressed by endothelial cells with very large cytoplasmic domains and is the second isotype, also known as scavenger receptor expressed by endothelial cells 2 (SREC-2). SREC-1 plays an important role in the binding and endocytosis of various endogenous and exogenous ligands. Many studies have been carried out on modified low-density lipoprotein internalization activity, but there have been few studies on SCARF2. Higher expression of SCARF2 has been found in glioblastoma (GBM) than normal brain tissue. Through analysis of The Cancer Genome Atlas database, it was confirmed that SCARF2 is widely expressed in GBM, and increased SCARF2 expression correlated with a poor prognosis in patients with glioma. The results of this study showed that the expression of SCARF2 is increased in GBM cell lines and patients, suggesting that SCARF2 may be a potential diagnostic marker and therapeutic molecule for cancers including glioma.

Corrigendum: Current Knowledge on the Function of α-Methyl Acyl-CoA Racemase in Human Diseases.

[This corrects the article DOI: 10.3389/fmolb.2020.00153.].

Alpha-Methylacyl-CoA Racemase (AMACR), a Potential New Biomarker for Glioblastoma.

Alpha-Methylacyl-CoA racemase (AMACR), which was initially discovered as a prostate cancer marker, is critical for the chiral inversion mechanism of branched-chain fatty acids. However, the function of AMACR in brain tumors has not been investigated. In this study, AMACR appeared to be involved in glioblastoma. The protein and mRNA levels of AMACR were highly elevated in glioblastoma. Downregulation of AMACR inhibited cell proliferation. Comprehensive analysis of the public REMBRANDT GBM dataset also confirmed that the level of AMACR expression was correlated with the clinical prognosis of glioma patients. In summary, these findings indicate that AMACR expression is increased in a glioblastoma cell line and glioma patients, suggesting that AMACR might be a potential diagnostic marker and therapeutic target for cancer, including glioma.

Current Knowledge on the Function of α-Methyl Acyl-CoA Racemase in Human Diseases.

Branched chain fatty acids perform very important functions in human diet and drug metabolism. they cannot be metabolized in mitochondria and are instead processed and degraded in peroxisomes due to the presence of methyl groups on the carbon chains. Oxidative degradation pathways for lipids include α- and ß-oxidation and several pathways. In all metabolic pathways, α-methyl acyl-CoA racemase (AMACR) plays an essential role by regulating the metabolism of lipids and drugs. AMACR regulates ß-oxidation of branched chain lipids in peroxisomes and mitochondria and promotes chiral reversal of 2-methyl acids. AMACR defects cause sensory-motor neuronal and liver abnormalities in humans. These phenotypes are inherited and are caused by mutations in AMACR. In addition, AMACR has been found to be overexpressed in prostate cancer. In addition, the protein levels of AMACR have increased significantly in many types of cancer. Therefore, AMACR may be an important marker in tumors. In this review, a comprehensive overview of AMACR studies in human disease will be described.

Revisiting the Warburg Effect: Diet-Based Strategies for Cancer Prevention.

It is widely acknowledged that cancer cell energy metabolism relies mainly on anaerobic glycolysis; this phenomenon is described as the Warburg effect. However, whether the Warburg effect is caused by genetic dysregulation in cancer or is the cause of cancer remains unknown. The exact reasons and physiology of this abnormal metabolism are unclear; therefore, many researchers have attempted to reduce malignant cell growth in tumors in preclinical and clinical studies. Anticancer strategies based on the Warburg effect have involved the use of drug compounds and dietary changes. We recently reviewed applications of the Warburg effect to understand the benefits of this unusual cancer-related metabolism. In the current article, we summarize diet strategies for cancer treatment based on the Warburg effect.

Yin Yang 1 is required for PHD finger protein 20-mediated myogenic differentiation in vitro and in vivo.

The development of skeletal muscle requires progression of a highly ordered cascade of events comprising myogenic lineage commitment, myoblast proliferation, and terminal differentiation. The process of myogenesis is controlled by several myogenic transcription factors that act as terminal effectors of signaling cascades and produce appropriate developmental stage-specific transcripts. PHD finger protein 20 (PHF20) is a multidomain protein and subunit of a lysine acetyltransferase complex that acetylates histone H4 and p53, but its function is unclear. Notably, it has been reported that PHF20 knockout mice die shortly after birth and display a wide variety of phenotypes within the skeletal and hematopoietic systems. Therefore, the putative role of PHF20 in myogenic differentiation was further investigated. In the present study, we found that protein and mRNA expression levels of PHF20 were decreased during myogenic differentiation in C2C12 cells. At the same time, Yin Yang 1 (YY1) was also decreased during myogenic differentiation. PHF20 overexpression increased YY1 expression during myogenic differentiation, together with a delay in MyoD expression. PHF20 expression enhanced the transcriptional activity of YY1 while shRNA-mediated depletion of PHF20 resulted in the reduction of YY1 promoter activity in C2C12 cells. In addition, PHF20 directly bounds to the YY1 promoter in C2C12 cells. In a similar manner, YY1 expression was elevated while myosin heavy chain expression was decreased in PHF20 transgenic (TG) mice. Histological analysis revealed abnormalities in the shape and length of muscles in PHF20-TG mice. Furthermore, PHF20-TG muscles slowly regenerated after cardiotoxin injection, indicating that PHF20 affected muscle differentiation and regeneration after injury in vivo. Taken together, these results suggested that PHF20 plays an important role in myogenic differentiation by regulating YY1.

Relationship Between Ginsenoside Rg3 and Metabolic Syndrome.

Metabolic syndrome is an important public health issue and is associated with a more affluent lifestyle. Many studies of metabolic syndrome have been reported, but its pathogenesis remains unclear and there is no effective treatment. The ability of natural compounds to ameliorate metabolic syndrome is currently under investigation. Unlike synthetic chemicals, such natural products have proven utility in various fields. Recently, ginsenoside extracted from ginseng and ginseng root are representative examples. For example, ginseng is used in dietary supplements and cosmetics. In addition, various studies have reported the effects of ginsenoside on metabolic syndromes such as obesity, diabetes, and hypertension. In this review, we describe the potential of ginsenoside Rg3, a component of ginseng, in the treatment of metabolic syndrome.

Association of p21-activated kinase-1 activity with aggressive tumor behavior and poor prognosis of head and neck cancer.

BACKGROUND: This study investigated the role of p21-activated kinase (PAK)-1 in progression of head and neck squamous cell carcinoma (HNSCC). METHODS: We examined PAK isoforms and explored whether PAK activation enhanced in vitro invasion of the HNSCC cell line. We analyzed the relationship between PAK1 expression and various clinicopathological features and investigated the effect of PAK1 overexpression on survival in 119 patients with HNSCC. RESULTS: PAK1 and PAK2 are predominantly expressed in HNSCC cells and patient tissues. Particularly, PAK1 makes the dominant contribution to increase in cell migration and invasion. There was a statistically significant correlation between PAK1 overexpression and aggressive cancer behavior. Moreover, PAK1 seemed to be a prognostic factor for overall and disease-specific survival in patients. Interestingly, enhancement of PAK1 expression was found in the invasive front of cancer. CONCLUSION: PAK1 is associated with the aggressive tumor behavior and poor prognosis of head and neck cancer.

SOCS3 and SOCS6 are required for the risperidone-mediated inhibition of insulin and leptin signaling in neuroblastoma cells.

Antipsychotic drugs are regularly used for the treatment of many types of psychiatric disorders. The administration of second-generation antipsychotics is often associated with weight gain and the development of diabetes mellitus; however, the molecular mechanisms underlying the effects of these drugs remain poorly understood. Leptin and insulin play key roles in the regulation of energy balance and glucose homeostasis, and resistance to the actions of these hormones can occur with obesity and inflammation, resulting in the pathogenesis of obesity and type 2 diabetes. In this study, the effects of risperidone on the insulin-induced protein kinase B (PKB) phosphorylation and leptin-stimulated signal transducer and activator of transcription 3 (STAT3) phosphorylation were investigated in the human SH-SY5Y neuroblastoma cell line. The treatment of these cells with risperidone induced the activation of extracellular signal-related kinase (ERK) by cellular cyclic adenosine 3-monophosphate (cAMP)-dependent protein kinase (also known as protein kinase A; PKA) and the mechanisms involved include the induction of suppressor of cytokine signaling 3 (SOCS3) and suppressor of cytokine signaling 6 (SOCS6) expression. The risperidone-induced ERK activation induced an upregulation of SOCS3 and SOCS6 mRNA expression levels. Taken together, these results suggest that risperidone modulates SOCS3 and SOCS6 expression through adenylate cyclase-mediated ERK activation, which, in turn, leads to an inhibition of insulin-induced PKB phosphorylation and leptin-stimulated STAT3 phosphorylation. Eventually, these effects result in excessive body weight gain due to the inhibition of both the leptin and insulin signaling pathways.

ß-Lapachone alleviates alcoholic fatty liver disease in rats.

UNLABELLED: Alcohol-induced liver injury is the most common liver disease in which fatty acid metabolism is altered. It is thought that altered NAD(+)/NADH redox potential by alcohol in the liver causes fatty liver by inhibiting fatty acid oxidation and the activity of tricarboxylic acid cycle reactions. ß-Lapachone (ßL), a naturally occurring quinone, has been shown to stimulate fatty acid oxidation in an obese mouse model by activating adenosine monophosphate-activated protein kinase (AMPK). In this report, we clearly show that ßL reduced alcohol-induced hepatic steatosis and induced fatty acid oxidizing capacity in ethanol-fed rats. ßL treatment markedly decreased hepatic lipids while serum levels of lipids and lipoproteins were increased in rats fed ethanol-containing liquid diets with ßL administration. Furthermore, inhibition of lipolysis, enhancement of lipid mobilization to mitochondria and upregulation of mitochondrial ß-oxidation activity in the soleus muscle were observed in ethanol/ßL-treated animals compared to the ethanol-fed rats. In addition, the activity of alcohol dehydrogenase, but not aldehyde dehydrogenase, was significantly increased in rats fed ßL diets. ßL-mediated modulation of NAD(+)/NADH ratio led to the activation of AMPK signaling in these animals. CONCLUSION: Our results suggest that improvement of fatty liver by ßL administration is mediated by the upregulation of apoB100 synthesis and lipid mobilization from the liver as well as the direct involvement of ßL on NAD(+)/NADH ratio changes, resulting in the activation of AMPK signaling and PPARα-mediated ß-oxidation. Therefore, ßL-mediated alteration of NAD(+)/NADH redox potential may be of potential therapeutic benefit in the clinical setting.

New players in high fat diet-induced obesity: LETM1 and CTMP.

OBJECTIVE: Obesity contributes to insulin resistance and is a risk factor for diabetes. C-terminal modulator protein (CTMP) and leucine zipper/EF-hand-containing transmembrane protein 1 (LETM1) have been reported to influence the phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB) signaling pathway via the modulation of PKB activity, a key player for insulin signaling. However, it remains unclear whether CTMP and LETM1 are associated with PI3K/PKB signaling in mouse models of obesity. MATERIALS/METHODS: To address this question, we used two different mouse models of obesity, including high-fat diet (HFD)-induced diabetic mice and genetically modified obese mice (ob/ob mice). The levels of insulin-signaling molecules in these mice were determined by immunohistochemical and Western blot analyses. The involvement of CTMP and LETM1 in PI3K/PKB signaling was investigated in HEK293 cells by transient transfection and adenovirus-mediated infection. RESULTS: We found that the levels of insulin receptor, phosphorylated PKB, and LETM1 were lower and the level of CTMP was higher in the adipose tissue of obese mice on an HFD compared to lean mice on a chow diet. Similar results were obtained in ob/ob mice. In HEK293 cells, the activation of PKB increased the LETM1 level, and inhibition of PKB increased the CTMP level. The overexpression of CTMP suppressed the insulin-induced increase in PKB phosphorylation, which was abrogated by co-overexpression with LETM1. CONCLUSION: These results suggest that CTMP and LETM1 may participate in impaired insulin signaling in the adipose tissue of obese mice, raising the possibility that these parameters may serve as new candidate biomarkers or targets in the development of new therapeutic approaches for diabetes.

Characterization of fragmented 3-phosphoinsitide-dependent protein kinase-1 (PDK1) by phosphosite-specific antibodies.

AIMS: The 3-phosphoinositide-dependent protein kinase-1 (PDK1) activates a number of protein kinases of the AGC subfamily, including protein kinase B and ribosomal S6 protein kinase by phosphorylating these kinases at the activation-loop. PDK1 activity is regulated by auto-phosphorylation and is further increased by stimulation of cells. PDK1 has been shown to have several phosphorylation sites including 5 serine and 3 tyrosine residues. However, Ser241 and Tyr373/376 are only involved in the regulation of PDK1 activity. MAIN METHODS: In this study, we found the putative fragments of PDK1 by using anti-Myc and anti-PDK1 antibodies. Furthermore, the existence of four different sizes of PDK1 were confirmed with other phosphosite specific antibodies. KEY FINDINGS: Taken together, the catalytic domain of PDK1 (42 kDa and 37 kDa) is separately existed in the cells and might be important for the regulation of subset of PDK1 substrate. Because the crystal structural studies suggested that PIF-pocket is located at the catalytic domain and plays a critical role on substrate recognition. SIGNIFICANCE: These suggested importance and roles of this fragment are needed to be determined. Further study on these fragments of PDK1 will provide new insight on the regulatory mechanism of PDK1 in patho-physiological condition.

Astrocytic phosphorylation of PDK1 on Tyr9 following an excitotoxic lesion in the mouse hippocampus.

3-phosphoinositide-dependent kinase-1 (PDK1) is suggested to play important roles in the regulation of synaptic plasticity and neuronal cell survival in the mature CNS. Although few studies have investigated the roles of PDK1, little is known about PDK1 changes in glial cells under neuropathological conditions. In current report, phosphorylation of PDK1 was monitored specially on tyrosine residues, following the induction of an excitotoxic lesion in rat brain by using kainic acid administration. In injured hippocampal CA3 region, Tyr9 phosphorylation of PDK1 was increased from 4h until 3 day post-injection. Double immunohistochemistry further evaluated that these phosphorylated forms of PDK1 were localized in astrocytes not other cells. Overexpression of unphosphorylatable mutant, PDK1-Y9F leads to inhibit Protein kinase B (PKB/Akt) activation and cAMP responsive element binding protein (CREB) phosphorylation. In conclusion, our results suggested for the first time that tyrosine phosphorylation of PDK1 is required for PKB and CREB activation in KA-mediated excitotoxic lesion in mouse brain.

PKB-mediated PHF20 phosphorylation on Ser291 is required for p53 function in DNA damage.

PHD finger protein 20 (PHF20) is a transcription factor, which was originally identified in glioma patients. PHF20 appears to be a novel antigen in glioma, and has also termed glioma-expressed antigen 2. PHF20 is thought to contribute to the development of cancers, including glioblastoma, lung cancer, colon cancer and ovarian cancer. However, little is known about the function of PHF20 in various cancers. Here we report that PHF20 contains two consensus sites for protein kinase B (PKB) phosphorylation (RxRxxS/T). PKB can directly phosphorylate PHF20 on Ser291 in vitro and in vivo. It has been shown that PKB participates in the tumor suppressor p53 regulated gene expression program and has a direct effect on p21 regulation after DNA damage. UV-induced DNA damage results in accumulation of p53 and PKB activation. Interestingly, PKB-mediated PHF20 phosphorylation led to an inhibition of p53 induction following UV treatment, leading to the reduction of p21 transcriptional activity. Using anti PHF20 and anti pPKB (S473) antibodies, these events were mapped in various human cancer tissues. Taken together, these data suggest that PHF20 is a novel substrate for PKB and its phosphorylation by PKB plays an important role in tumorigenesis via regulating of p53 mediated signaling.