• BMB Reports
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• 제46권1호
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• pp.1-8
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• 2013

Phosphoinositides are the phosphorylated derivatives of phosphatidylinositol, and play a very significant role in a diverse range of signaling processes in eukaryotic cells. A number of phosphoinositide-metabolizing enzymes, including phosphoinositide-kinases and phosphatases are involved in the synthesis and degradation of these phospholipids. Recently, the function of various phosphatases in the phosphatidylinositol signaling pathway has been of great interest. In the present review we summarize the structural insights and biochemistry of various phosphatases in regulating phosphoinositide metabolism.

• BMB Reports
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• 제47권7호
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• pp.361-368
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• 2014

Lipid components in biological membranes are essential for maintaining cellular function. Phosphoinositides, the phosphorylated derivatives of phosphatidylinositol (PI), regulate many critical cell processes involving membrane signaling, trafficking, and reorganization. Multiple metabolic pathways including phosphoinositide kinases and phosphatases and phospholipases tightly control spatio-temporal concentration of membrane phosphoinositides. Metabolizing enzymes responsible for PI 4,5-bisphosphate (PI(4,5)P2) production or degradation play a regulatory role in Toll-like receptor (TLR) signaling and trafficking. These enzymes include PI 4-phosphate 5-kinase, phosphatase and tensin homolog, PI 3-kinase, and phospholipase C. PI(4,5)P2 mediates the interaction with target cytosolic proteins to induce their membrane translocation, regulate vesicular trafficking, and serve as a precursor for other signaling lipids. TLR activation is important for the innate immune response and is implicated in diverse pathophysiological disorders. TLR signaling is controlled by specific interactions with distinct signaling and sorting adaptors. Importantly, TLR signaling machinery is differentially formed depending on a specific membrane compartment during signaling cascades. Although detailed mechanisms remain to be fully clarified, phosphoinositide metabolism is promising for a better understanding of such spatio-temporal regulation of TLR signaling and trafficking.

• 환경위생공학
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• 제16권3호
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• pp.14-21
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• 2001

The effects of sodium molybdate(Mo) on phospholipid metabolism in sciatic nerve isolated from lead-intoxicated rat were investigated. Four weeks aged albino rats were divided into four groups : normal control group, lead(10 ppm)-treated group, Mo(1 mg/kg)-treated group, lead and Mo-treated group. As a result of the study, Mo significantly increased the rate of incorporation of $2-[^3H]$myo-inositol into polyphosphinositides in lead-intoxicated rat. Mo also increased the rate of phosphatidylcholine metabolism in normal and lead-intoxicated rats. However, Mo did not affect the metabolism of phosphatidylserine and phosphatidylethanola-mine in normal and lead-intoxicated status. These results suggest that Mo might improve lead-intoxicated status by principally enhancing the metabolism of myo-inositol-related phospholipids and by partly phosphatidylcholine in sciatic nerve.

• 환경위생공학
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• 제16권4호
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• pp.1-8
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• 2001

We have previously demonstrated that sodium molybdate(Mo) improved lead-intoxicated status by enhancing the metabolism of mao-inositol-related phospholipids in sciatic nerves isolated from rats. In this study, in order to address the reduction mechanism of Mo for lead toxicity, effects of Mo on cystidine-diglyceride transferase, phosphatidylinositol kinase, and phosphatidyl inositol-4-phosphate kinase, involved in mao-inositol metabolism of nerve, were investigated in vivo and in vitro. Mo significantly increased the activities of cystidine- diglyceride transferase and phosphatidylinositol kinase in lead-intoxicated rat, and the pattern of increase was dose-dependent manner. However, Mo did not affect the activity of phosp- hatidylinositiol-4-phosphate kinase in normal and lead-intoxicated rats. We also found that Mo affected the activities of phopholipid metabolism-related enzymes not by the indirect manner such as activation of another metabolic pathway but by the direct manner. These results suggest that the improvement mechanism of Mo for lead-intoxicated status might be a normalization of the activities of phospholipid metabolism-related enzymes in sciatic nerve.

• 한국산학기술학회논문지
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• 제12권7호
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• pp.3310-3316
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• 2011

Hematoxylin은 한국의 남부지방에서 당뇨합병증을 치료하기 위하여 사용해오던 민간약제인 Hematoxylon campechianum의 주성분이다. 본 논문에서는 hematoxylin의 혈당저하 메커니즘을 연구하기 위하여 3개 군의 흰쥐-정상군, 당뇨군, hematoxylin 처치군-에서 분리한 대퇴신경을 대상으로 2-deoxyglucose 수송능과 인지질 대사능을 조사였다. 실험결과 hematoxylin은 당뇨군에서 혈당치를 현저하게 감소시키는 것으로 나타났다. 또한 무게단위의 기준으로 당뇨군의 신경조직의 경우, 총 인지질의 양은 20% 감소하였으나 상대적으로 phosphatidylinositide의 감소는 작은 것으로 나타났다. 이 경우, hematoxylin을 처치하면 2-[3H] myo-inositol이 총 phosphoinositids로 대사되는 비율이 증가하는 것으로 밝혀졌다. 이러한 효과는 낮은 농도의 hematoxylin 처치군보다 높은 농도의 처치군에서 훨씬 큰 것으로 나타났다. 이상의 실험결과는 hematoxylin의 당뇨개선 메커니즘이 myo-inositol 대사를 증가시킴으로써 체내 당 수송과 인지질 대사를 정상화시킨다는 점을 제시하고 있다. 따라서 본 연구결과를 토대로 저자들은 hematoxylin은 향후 당뇨 치료제로서 후보 물질이 될 수 있음을 제시하고자 한다.

• Molecules and Cells
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• 제44권8호
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• pp.613-622
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• 2021

In vertebrate eyes, the retinal pigment epithelium (RPE) provides structural and functional homeostasis to the retina. The RPE takes up retinol (ROL) to be dehydrogenated and isomerized to 11-cis-retinaldehyde (11-cis-RAL), which is a functional photopigment in mammalian photoreceptors. As excessive ROL is toxic, the RPE must also establish mechanisms to protect against ROL toxicity. Here, we found that the levels of retinol dehydrogenases (RDHs) are commonly decreased in phosphatase tensin homolog (Pten)-deficient mouse RPE, which degenerates due to elevated ROL and that can be rescued by feeding a ROL-free diet. We also identified that RDH gene expression is regulated by forkhead box O (FOXO) transcription factors, which are inactivated by hyperactive Akt in the Pten-deficient mouse RPE. Together, our findings suggest that a homeostatic pathway comprising PTEN, FOXO, and RDH can protect the RPE from ROL toxicity.

• Journal of Yeungnam Medical Science
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• 제7권1호
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• pp.39-50
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• 1990

세포막의 정보전달기전중 phosphoinositide system은 정보가 전달될때 phospholipase C 효소의 작용으로 phosphatidyl inositol bisphosphate로부터 inositol triphosphate($IP_3$)와 diacylglycerol이 생성되며 $IP_3$는 다시 $IP_3$kinase에 의해 inositol tetrakisphosphate($IP_4$)로 되어 이차전령 물로서 작용한다. 본 연구는 $IP_3$kinase효소가 $Ca^{2+}$와 calmodulin에 의해 활성화되는 성질을 이용하여 calmodulin을 정제하고 $IP_3$kinase효소와의 친화도를 비교 관찰하였다. Calmodulin정제는 phenyl-Sepharose resin을 이용하여 column chromatography를 시행하여 정제확인하였으며 분자량이 17,000임을 SDS-polyacrylamide gel 전기영동으로 확인하였다. 정제된 calmodulin을 affigel column에 결합시킨 gel에 소의 뇌로부터 분리한 $IP_3$kinase효소가 담긴 시료를 calmodulin-affigel column에 적용하여 결합 및 유출정도를 비교하였으며 $Ca^{2+}$이 든 buffer에서 친화도가 가장 컸으며 유출은 EGTA용액에서 일부 유출되었으며 calmodulin/$Ca^{2+}$이 든 buffer에선 강한 유출정도를 관찰하였다. 그러나 calmodulin/$Ca^{2+}$는 $IP_3$kinase효소의 활성을 증가시키며 calmodulin이 단백질이어서 정제면에서 효소와의 분리가 쉽지않아 여러 다른 detergent를 적용하였으나 0.2% chaps buffer에서 집중된 유출을 관찰하였다.

• 한방비만학회지
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• 제22권2호
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• pp.102-114
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• 2022

Objectives: We investigated the effects of Allii Fistulosi Bulbus (AFB) on high fat diet (HFD)-induced obesity in mice and the regulation of energy metabolism in muscle tissues of mice. Methods: The C57BL/6 mice (6 weeks, male) were fed a HFD for 8 weeks and then administrated with AFB extract at 500 mg/kg (p.o.) once daily for 4 weeks. The body weight (BW), muscle weight, calorie intake, fasting blood glucose (FBG) and serum glucose, insulin, and low-density lipoprotein-cholesterol (LDL-C) levels were measured in mice. It was also observed the histological changes of pancreas, liver, and fat tissues with hematoxylin and eosin staining. It was investigated the phosphorylation of insulin receptor substrate 1 (IRS-1), Ser/Thr kinase (AKT), and adenosine monophosphate-activated protein kinase (AMPK), and the expression of phosphoinositide 3-kinase, glucose transporter type 4 (GLUT4), and sirtuin1 (Sirt1) in gastrocnemius tissues by western blot, respectively. Results: The increases of BWs, calorie intakes and FBG levels in obesity mice were decreased significantly by the administration of AFB extract. The AFB extract administration was reduced significantly serum levels of glucose, insulin, and LDL-C in obesity mice. The AFB extract inhibited lipid accumulation in liver tissues, hyperplasia of pancreatic islets, and enlargement of fat tissues in obesity mice. The phosphorylation of IRS-1 and AKT was increased significantly in muscle tissues and AMPK phosphorylation and the GLUT4 and Sirt1 expression were decreased significantly in muscle tissues after the AFB administration. Conclusions: Our study indicates that AFB extract improves symptoms of obesity through regulation of energy regulating proteins in muscle tissues.

• Journal of Animal Science and Technology
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• 제64권3호
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• pp.481-499
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• 2022

This study aims to determine the effects of D-methionine (D-Met) isomer and the methionine precursor 2-hydroxy-4-methylthiobutanoic acid i (HMBi) supplementation on milk protein synthesis on immortalized bovine mammary epithelial cell (MAC-T). MAC-T cells were seeded using 10-cm dishes and cultured in Dulbecco's modified Eagle's medium/F12 (DMEM/F12) basic medium. The basic medium of DMEM/F12 was replaced with the lactogenic DMEM/ F12 differentiation medium when 90% of MAC-T cells reached confluency. The best dosage at 0.6 mM of D-Met and HMBi and incubation time at 72 h were used uniformly for all treatments. Each treatment was replicated six times wherein treatments were randomly assigned in a 6-well plate. Cell, medium, and total protein were determined using a bicinchoninic acid protein assay kit. Genes, proteomics and metabolomics analyses were also done to determine the mechanism of the milk protein synthesis pathway. Data were analyzed by two-way analysis of variance (ANOVA) with supplement type and plate as fixed effects. The least significant difference test was used to evaluate the differences among treatments. The HMBi treatment group had the highest beta-casein and S6 kinase beta-1 (S6K1) mRNA gene expression levels. HMBi and D-Met treatments have higher gene expressions compared to the control group. In terms of medium protein content, HMBi had a higher medium protein quantity than the control although not significantly different from the D-Met group. HMBi supplementation stimulated the production of eukaryotic translation initiation factor 3 subunit protein essential for protein translation initiation resulting in higher medium protein synthesis in the HMBi group than in the control group. The protein pathway analysis results showed that the D-Met group stimulated fructose-galactose metabolism, glycolysis pathway, phosphoinositide 3 kinase, and pyruvate metabolism. The HMBi group stimulated the pentose phosphate and glycolysis pathways. Metabolite analysis revealed that the D-Met treatment group increased seven metabolites and decreased uridine monophosphate (UMP) production. HMBi supplementation increased the production of three metabolites and decreased UMP and N-acetyl-L-glutamate production. Taken together, D-Met and HMBi supplementation are effective in stimulating milk protein synthesis in MAC-T cells by genes, proteins, and metabolites stimulation linked to milk protein synthesis.

• 생명과학회지
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• 제31권8호
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• pp.729-735
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• 2021

제 2 형 당뇨병은 조직의 포도당 흡수 능력에 이상이 있을 때 발생하며, 인슐린에 의한 포도당 섭취와 신진대사는 혈당을 유지하는 기본 활동이며 포도당 섭취는 인슐린이 세포 표면의 수용체에 결합하여 시작되는 다양한 신호 단계를 거친다. 본 연구는 Ecklonia cava에서 분리된 활성 화합물 인 2,7-phloroglucinol-6,6-bieckol이 3T3-L1 지방 세포에서 인슐린 신호전달체계에 따른 포도당 흡수 증가에 미치는 영향에 대한 것이다. 2,7-phloroglucinol-6,6-bieckol 은 3T3-L1 지방 세포에서 농도의존적으로 GLUT4의 발현을 증가시켜 원형질막에서의 glucose uptake 를 증가시켰다. 이는 인슐린 신호 전달 경로에서 2,7-phloroglucinol-6,6-bieckol 에 의한 IRS-1, AKT의 인산화 및 PI3K 활성화에 의한 것이다. PHB는 또한 AMPK 인산화와 활성화를 자극했다. 2,7-phloroglucinol-6,6-bieckol에 의한 PI3K/AKT 및 AMPK 경로의 인산화 및 활성화는 wortmannin (PI3K 억제제) 및 화합물 C (AMPK 억제제)를 사용하여 확인하였다. 본 연구에서 2,7-phloroglucinol-6,6-bieckol 이 3T3-L1 지방 세포에서 PI3K 및 AMPK 경로를 통해 원형질막으로의 GLUT4 전위를 촉진함으로써 포도당 흡수를 증가시킬 수 있음을 나타내었다. 이러한 결과는 2,7-phloroglucinol-6,6-bieckol 가 인슐린 감수성을 개선하는 데 도움이 될 수 있음을 시사한다.