Exogenous regucalcin suppresses osteoblastogenesis and stimulates adipogenesis in mouse bone marrow culture

Overexpression of RGPR-p117 reveals anticancer effects by regulating multiple signaling pathways in bone metastatic human breast cancer MDA-MB-231 cells

The role of RGPR-p117, a transcription factor, which binds to the TTGGC motif in the promoter region of the regucalcin gene, in cell regulation remains to be investigated. This study elucidated whether RGPR-p117 regulates the activity of triple-negative human breast cancer MDA-MB-231 cells in vitro. The wild-type and RGPR-p117-overexpressing cancer cells were cultured in DMEM supplemented with fetal bovine serum. RGPR-p117 overexpression suppressed colony formation and growth of cancer cells. Stimulatory effects of epidermal growth factor on cell growth were blocked by RGPR-p117 overexpression. Wild-type cell proliferation was repressed by cell cycle and intracellular signaling inhibitors. These effects were not potentiated in transfectants. Overexpressed RGPR-p117 protected cancer cells against apoptosis inducers. Mechanistic results showed that RGPR-p117 overexpression decreased the expression of Ras, PI3-kinase, Akt, mitogen-activated protein kinase, and mTOR, which are involved in cell growth, while it elevated the levels of the cancer cell suppressor p53, Rb, p21, and regucalcin. Overexpression of RGPR-p117 suppressed cancer cell migration and adhesion. Interestingly, osteoblastic MC3T3-E1 cells or macrophage RAW264.7 cells involved in the bone microenvironment were impaired by coculture with MDA-MB-231 cells. The effects of cancer cells were blocked by transfection. Coculture with conditioned medium obtained from breast cancer cells repressed proliferation and enhanced the death of osteoblastic cells and macrophages. A TNF-α signaling inhibitor blocked these effects. Thus, overexpressed RGPR-p117 was found to suppress the activity of breast cancer cells by regulating various signaling processes, providing new insight into cellular signaling regulation.

Discovery of potential biomarkers for osteoporosis using LC/GC-MS metabolomic methods

Purpose

For early diagnosis of osteoporosis (OP), plasma metabolomics of OP was studied by untargeted LC/GC-MS in a Chinese elderly population to find possible diagnostic biomarkers.

Methods

A total of 379 Chinese community-dwelling older adults aged ≥65 years were recruited for this study. The BMD of the calcaneus was measured using quantitative ultrasound (QUS), and a T value ≤-2.5 was defined as OP. Twenty-nine men and 47 women with OP were screened, and 29 men and 36 women were matched according to age and BMI as normal controls using propensity matching. Plasma from these participants was first analyzed by untargeted LC/GC-MS, followed by FC and P values to screen for differential metabolites and heatmaps and box plots to differentiate metabolites between groups. Finally, metabolic pathway enrichment analysis of differential metabolites was performed based on KEGG, and pathways with P ≤ 0.05 were selected as enrichment pathways.

Results

We screened metabolites with FC>1.2 or FC<1/1.2 and P<0.05 and found 33 differential metabolites in elderly men and 30 differential metabolites in elderly women that could be potential biomarkers for OP. 2-Aminomuconic acid semialdehyde (AUC=0.72, 95% CI 0.582-0.857, P=0.004) is highly likely to be a biomarker for screening OP in older men. Tetradecanedioic acid (AUC=0.70, 95% CI 0.575-0.818, P=0.004) is highly likely to be a biomarker for screening OP in older women.

Conclusion

These findings can be applied to clinical work through further validation studies. This study also shows that metabolomic analysis has great potential for application in the early diagnosis and recurrence monitoring of OP in elderly individuals.

C. R. Twelve Weeks of Whole Body Vibration Training Improve Regucalcin, Body Composition and Physical Fitness in Postmenopausal Women: A Pilot Study

(1) Background: Regucalcin or senescence marker protein 30 (SMP30) is a Ca2+ binding protein discovered in 1978 with multiple functions reported in the literature. However, the impact of exercise training on SMP30 in humans has not been analyzed. Aging is associated with many detrimental physiological changes that affect body composition, functional capacity, and balance. The present study aims to investigate the effects of whole body vibration (WBV) in postmenopausal women. (2) Methods: A total of 13 women (aged 54.3 ± 3.4 years) participated in the study. SMP30, body composition (fat mass, lean mass, and bone mass) and physical fitness (balance, time up and go (TUG) and 6-min walk test (6MWT)) were measured before and after the 12 weeks of WBV training. (3) Results: The WBV training program elicited a significant increase in SPM30 measured in plasma (27.7%, p = 0.004) and also in 6MWT (12.5%, p < 0.001). The WBV training also significantly reduced SPM30 measured in platelets (38.7%, p = 0.014), TUG (23.1%, p < 0.001) and total body fat mass (4.4%, p = 0.02). (4) Conclusions: There were no significant differences in balance, lean mass or bone mass. The present study suggests that 12 weeks of WBV has the potential to improve SPM30, fat mass, TUG and 6MWT in postmenopausal women.

Involvement of regucalcin gene promoter region-related protein-p117, a transcription factor, in human obesity

Regucalcin gene promoter region-related protein-p117 (RGPR-p117; gene symbol, rgpr-117) was identified in 2001 as a novel transcription factor that specifically binds to a nuclear factor I consensus motif, TTGGC(N)₆CC in the promoter region of the regucalcin (rgn) gene. The human RGPR-p117 gene consists of 26 exons spanning ~4.1 kbp and is localized on chromosome 1q25.2. The nuclear translocation of cytoplasm RGPR-p117 is mediated via the protein kinase C-dependent signaling pathway. Overexpression of RGPR-p117 enhances the transcription activity of rgn, and a protective effect on cell death by inhibition of gene expression levels of caspase-3, caspase-8 and FADD proteins that possess the TTGGC motif in the promoter region of those genes was revealed. RGPR-p117 has a crucial role as a transcription factor. Notably, RGPR-p117 was shown to localize in the plasma membranes, mitochondria and microsomes (endoplasmic reticulum; ER). RGPR-p117, which is located in the ER, was also shown to have a role as an ER export factor implicated in the transports of proteins and lipids. As a result of this finding, it was proposed in 2007 that RGPR-p117 is renamed SEC 16 homolog B, endoplasmic reticulum export factor (SEC16B). Recently, there is increasing evidence that RGPR-p117/SEC16B may be involved in human obesity. Thus, the current review presents data regarding the involvement of RGPR-p117 in human obesity.

β-Caryophyllene promotes osteoblastic mineralization, and suppresses osteoclastogenesis and adipogenesis in mouse bone marrow cultures in vitro

Osteoporosis is induced by the reduction in bone mass through decreased osteoblastic osteogenesis and increased osteoclastic bone resorption, and it is associated with obesity and diabetes. Osteoblasts and adipocytes are derived from bone marrow mesenchymal stem cells. The prevention of osteoporosis is an important public health concern in aging populations. β-caryophyllene, a component of various essential oils, is a selective agonist of the cannabinoid receptor type 2 and exerts cannabimimetic anti-inflammatory effects in animals. The present study aimed to identify the effect of β-caryophyllene on adipogenesis, osteoblastic mineralization and osteoclastogenesis in mouse bone marrow cell cultures in vitro. Bone marrow cells obtained from mouse femoral tissues were cultured in the presence of β-caryophyllene (0.1-100 µM) in vitro. The results revealed that β-caryophyllene stimulated osteoblastic mineralization, and suppressed adipogenesis and osteoclastogenesis. Thus, β-caryophyllene may be used as a therapeutic agent for the prevention and treatment of osteoporosis.

Regucalcin expression in bovine tissues and its regulation by sex steroid hormones in accessory sex glands

Regucalcin (RGN) is a mammalian Ca2+-binding protein that plays an important role in intracellular Ca2+ homeostasis. Recently, RGN has been identified as a target gene for sex steroid hormones in the prostate glands and testis of rats and humans, but no studies have focused on RGN expression in bovine tissues. Thus, in the present study, we examined RGN mRNA and protein expression in the different tissues and organs of veal calves and beef cattle. Moreover, we investigated whether RGN expression is controlled through sex steroid hormones in bovine target tissues, namely the bulbo-urethral and prostate glands and the testis. Sex steroid hormones are still illegally used in bovine husbandry to increase muscle mass. The screening of the regulation and function of anabolic sex steroids via modified gene expression levels in various tissues represents a new approach for the detection of illicit drug treatments. Herein, we used quantitative PCR, western blot and immunohistochemistry analyses to demonstrate RGN mRNA and protein expression in bovine tissues. In addition, estrogen administration down-regulated RGN gene expression in the accessory sex glands of veal calves and beef cattle, while androgen treatment reduced RGN gene expression only in the testis. The confirmation of the regulation of RGN gene expression through sex steroid hormones might facilitate the potential detection of hormone abuse in bovine husbandry. Particularly, the specific response in the testis suggests that this tissue is ideal for the detection of illicit androgen administration in veal calves and beef cattle.

Curcumin analogue UBS109 prevents bone loss in breast cancer bone metastasis mouse model: involvement in osteoblastogenesis and osteoclastogenesis

Bone metastasis of breast cancer typically leads to osteolysis, which causes severe pathological bone fractures and hypercalcemia. Bone homeostasis is skillfully regulated through osteoblasts and osteoclasts. Bone loss with bone metastasis of breast cancer may be due to both activation of osteoclastic bone resorption and suppression of osteoblastic bone formation. This study was undertaken to determine whether the novel curcumin analogue UBS109 has preventive effects on bone loss induced by breast cancer cell bone metastasis. Nude mice were inoculated with breast cancer MDA-MB-231 bone metastatic cells (10(6) cells/mouse) into the head of the right and left tibia. One week after inoculation, the mice were treated with control (vehicle), oral administration (p.o.) of UBS109 (50 or 150 mg/kg body weight), or intraperitoneal administration (i.p.) of UBS109 (10 or 20 mg/kg body weight) once daily for 5 days per week for 7 weeks. After UBS109 administration for 7 weeks, hind limbs were assessed using an X-ray diagnosis system and hematoxylin and eosion staining to determine osteolytic destruction. Bone marrow cells obtained from the femurs and tibias were cultured to estimate osteoblastic mineralization and osteoclastogenesis ex vivo and in vitro. Remarkable bone loss was demonstrated in the tibias of mice inoculated with breast cancer MDA-MB-231 bone metastatic cells. This bone loss was prevented by p.o. administration of UBS109 (50 and 150 mg/kg body weight) and i.p. treatment of UBS109 (10 and 20 mg/kg) in vivo. Culture of bone marrow cells obtained from the bone tissues of mice with breast cancer cell bone metastasis showed suppressed osteoblastic mineralization and stimulated osteoclastogenesis ex vivo. These changes were not seen after culture of the bone marrow cells obtained from mice treated with UBS109. Moreover, UBS109 was found to stimulate osteoblastic mineralization and suppress lipopolysaccharide (LPS)-induced osteoclastogenesis in bone marrow cells obtained from normal nude mice in vitro. These findings suggest that the novel curcumin analogue UBS109 prevents breast cancer cell bone metastasis-induced bone loss by stimulating osteoblastic mineralization and suppressing osteoclastogenesis.

The role of regucalcin in bone homeostasis: involvement as a novel cytokine

Regucalcin, which was discovered as a calcium-binding protein in 1978, has been demonstrated to play a multifunctional role in the regulation of various tissues and cell types. Regucalcin plays a pivotal role in the regulation of intracellular calcium homeostasis, various enzyme activities, cell signal transduction, nuclear function and gene expression, and cell proliferation and apoptosis. Moreover, regucalcin has been found to play a role in the regulation of bone homeostasis. Overexpression of regucalcin induces bone loss in regucalcin transgenic rats in vivo and deficiency causes osteomalacia in vivo. Regucalcin mRNA and its protein are expressed in rat femoral tissues, bone marrow cells, and osteoblastic cells. Exogenous regucalcin has suppressive effects on the differentiation and mineralization of osteoblastic MC3T3-E1 cells and stimulates osteoclastogenesis in mouse bone marrow culture in vitro. Moreover, regucalcin has been found to suppress osteoblastogenesis and stimulate adipogenesis in the bone marrow culture system in vitro. Regucalcin shows enhancing effects on activation of NF-κB, which is mediated through tumor necrosis factor-α (TNF-α) or the receptor activator of the NF-κB ligand (RANKL) in preosteoblastic cells and preosteoclastic cells. Exogenous regucalcin may play a pivotal role in the regulation of bone homeostasis as a suppressor in osteoblastogenesis and an enhancer in osteoclastogenesis, suggesting its role as a cytokine.

Novel regulatory roles of omega-3 fatty acids in metabolic pathways: a proteomics approach

Background

Omega-3 polyunsaturated fatty acids (n-3 PUFA) have been shown to alleviate the symptoms of metabolic disorders, such as heart disease, diabetes, obesity and insulin resistance. Several putative mechanisms by which n-3 PUFA elicit beneficial health effects have been proposed; however, there is still a shortage of knowledge on the proteins and pathways that are regulated by n-3 PUFA.

Methods

Using two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, we investigated the effects of diets high or low in n-3 PUFA on hepatic proteomic profile of C57BL/6 mice.

Results

The findings show for the first time that high dietary n-3 PUFA reduced the expression of regucalcin, adenosine kinase and aldehyde dehydrogenase. On the other hand, diets high in n-3 PUFA increased the expression of apolipoprotein A-I, S-adenosylmethionine synthase, fructose-1, 6-bisphosphatase, ketohexokinase, malate dehydrogenase, GTP-specific succinyl CoA synthase, ornithine aminotransferase and protein disulfide isomerase-A3.

Conclusions

Our findings revealed for the first time that n-3 PUFA causes alterations in several novel functional proteins involved in regulating lipid, carbohydrate, one-carbon, citric acid cycle and protein metabolism, suggesting integrated regulation of metabolic pathways. These novel proteins are potential targets to develop therapeutic strategies against metabolic disorders.

Bioactive flavonoid p-hydroxycinnamic acid stimulates osteoblastogenesis and suppresses adipogenesis in bone marrow culture

The bioactive flavonoid p-hydroxycinnamic acid (HCA), which is an intermediate-metabolic substance in plants and fruits, is synthesized from tyrosine. The biological effect of HCA is poorly understood. Among cinnamic acid and its related compounds, HCA has a specific-anabolic effect on bone, being found to stimulate osteoblastogenesis and to inhibit osteoclastogenesis through the suppression of NF-κB signaling, thereby preventing bone loss. Bone marrow mesenchymal stem cells give rise to ostoblasts and adipocytes. HCA might therefore have effects on osteoblastogenesis and adipogenesis in bone marrow culture. This study demonstrates (1) that HCA has stimulatory effects on osteoblastogenesis and mineralization and suppressive effects on adipogenesis in mouse bone marrow culture and (2) that HCA depresses adipogenesis in mouse 3T3-L1 preadipocytes in vitro. Such effects of HCA might be involved in the differentiation of mesenchymal stem cells.

Involvement of regucalcin in lipid metabolism and diabetes

Regucalcin (RGN/SMP30) was originally discovered in 1978 as a unique calcium-binding protein that does not contain the EF-hand motif of calcium-binding domain. The regucalcin gene (rgn) is localized on the X chromosome and is identified in over 15 species consisting the regucalcin family. Regucalcin has been shown to play a multifunctional role in cell regulation; maintaining of intracellular calcium homeostasis and suppressing of signal transduction, translational protein synthesis, nuclear deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) synthesis, proliferation, and apoptosis in many cell types. Moreover, regucalcin may play a pathophysiological role in metabolic disorder. The expression of regucalcin is stimulated through the action of insulin in liver cells in vitro and in vivo and it is decreased in the liver of rats with type I diabetes induced by streptozotocin administration in vivo. Overexpression of endogenous regucalcin stimulates glucose utilization and lipid production in liver cells with glucose supplementation in vitro. Regucalcin reveals insulin resistance in liver cells. Deficiency of regucalcin induces an impairment of glucose tolerance and lipid accumulation in the liver of mice in vivo. Overexpression of endogenous regucalcin has been shown to decrease triglyceride, total cholesterol and glycogen contents in the liver of rats, inducing hyperlipidemia. Leptin and adiponectin mRNA expressions in the liver tissues are decreased in regucalcin transgenic rats. Decrease in hepatic regucalcin is associated with the development and progression of nonalcoholic fatty liver disease and fibrosis in human patients. Regucalcin may be a key molecule in lipid metabolic disorder and diabetes.