Lack of SPNS1 results in accumulation of lysolipids and lysosomal storage disease in mouse models.

Accumulation of sphingolipids, especially sphingosines, in the lysosomes is a key driver of several lysosomal storage diseases. The transport mechanism for sphingolipids from the lysosome remains unclear. Here, we identified SPNS1, which shares the highest homology to SPNS2, a sphingosine-1-phosphate (S1P) transporter, functions as a transporter for lysolipids from the lysosome. We generated Spns1-KO cells and mice and employed lipidomic and metabolomic approaches to reveal SPNS1 ligand identity. Global KO of Spns1 caused embryonic lethality between E12.5 and E13.5 and an accumulation of sphingosine, lysophosphatidylcholines (LPC), and lysophosphatidylethanolamines (LPE) in the fetal livers. Similarly, metabolomic analysis of livers from postnatal Spns1-KO mice presented an accumulation of sphingosines and lysoglycerophospholipids including LPC and LPE. Subsequently, biochemical assays showed that SPNS1 is required for LPC and sphingosine release from lysosomes. The accumulation of these lysolipids in the lysosomes of Spns1-KO mice affected liver functions and altered the PI3K/AKT signaling pathway. Furthermore, we identified 3 human siblings with a homozygous variant in the SPNS1 gene. These patients suffer from developmental delay, neurological impairment, intellectual disability, and cerebellar hypoplasia. These results reveal a critical role of SPNS1 as a promiscuous lysolipid transporter in the lysosomes and link its physiological functions with lysosomal storage diseases.

Kidney derived apolipoprotein M and its role in acute kidney injury.

Aim: Apolipoprotein M (apoM) is mainly expressed in liver and in proximal tubular epithelial cells in the kidney. In plasma, apoM associates with HDL particles via a retained signal peptide and carries sphingosine-1-phosphate (S1P), a small bioactive lipid. ApoM is undetectable in urine from healthy individuals but lack of megalin receptors in proximal tubuli cells induces loss of apoM into the urine. Besides this, very little is known about kidney-derived apoM. The aim of this study was to address the role of apoM in kidney biology and in acute kidney injury. Methods: A novel kidney-specific human apoM transgenic mouse model (RPTEC-hapoMTG) was generated and subjected to either cisplatin or ischemia/reperfusion injury. Further, a stable transfection of HK-2 cells overexpressing human apoM (HK-2-hapoMTG) was developed to study the pattern of apoM secretion in proximal tubuli cells. Results: Human apoM was present in plasma from RPTEC-hapoMTG mice (mean 0.18 µM), with a significant increase in plasma S1P levels. In vitro apoM was secreted to both the apical (urine) and basolateral (blood) compartment from proximal tubular epithelial cells. However, no differences in kidney injury score was seen between RPTEC-hapoMTG and wild type (WT) mice upon kidney injury. Further, gene expression of inflammatory markers (i.e., IL6, MCP-1) was similar upon ischemia/reperfusion injury. Conclusion: Our study suggests that kidney-derived apoM is secreted to plasma, supporting a role for apoM in sequestering molecules from excretion in urine. However, overexpression of human apoM in the kidney did not protect against acute kidney injury.

Deficiency in the omega-3 lysolipid transporter Mfsd2a leads to aberrant oligodendrocyte lineage development and hypomyelination.

Patients with autosomal recessive microcephaly 15 caused by deficiency in the sodium-dependent lysophosphatidylcholine (LPC) transporter major facilitator superfamily domain-containing 2a (Mfsd2a) present with both microcephaly and hypomyelination, suggesting an important role for LPC uptake by oligodendrocytes in the process of myelination. Here we demonstrate that Mfsd2a is specifically expressed in oligodendrocyte precursor cells (OPCs) and is critical for oligodendrocyte development. Single-cell sequencing of the oligodendrocyte lineage revealed that OPCs from OPC-specific Mfsd2a-KO mice (2aOKO mice) underwent precocious differentiation into immature oligodendrocytes and impaired maturation into myelinating oligodendrocytes, correlating with postnatal brain hypomyelination. 2aOKO mice did not exhibit microcephaly, a finding consistent with the notion that microcephaly is the consequence of an absence of LPC uptake at the blood-brain barrier rather than a deficiency in OPCs. Lipidomic analysis showed that OPCs and iOLs from 2aOKO mice had significantly decreased levels of phospholipids containing omega-3 fatty acids, with a corresponding increase in unsaturated fatty acids, the latter being products of de novo synthesis governed by Srebp-1. RNA-Seq indicated activation of the Srebp-1 pathway and defective expression of regulators of oligodendrocyte development. Taken together, these findings indicate that the transport of LPCs by Mfsd2a in OPCs is important for maintaining OPC state to regulate postnatal brain myelination.

Loss of ABCA8B decreases myelination by reducing oligodendrocyte precursor cells in mice.

The myelin sheath, which is wrapped around axons, is a lipid-enriched structure produced by mature oligodendrocytes. Disruption of the myelin sheath is observed in several neurological diseases, such as multiple sclerosis. A crucial component of myelin is sphingomyelin, levels of which can be increased by ABCA8, a member of the ATP-binding cassette transporter family. ABCA8 is highly expressed in the cerebellum, specifically in oligodendroglia. However, whether ABCA8 plays a role in myelination and mechanisms that would underlie this role remain unknown. Here, we found that the absence of Abca8b, a mouse ortholog of ABCA8, led to decreased numbers of cerebellar oligodendrocyte precursor cells (OPCs) and mature oligodendrocytes in mice. We show that in oligodendrocytes, ABCA8 interacts with chondroitin sulfate proteoglycan 4 (CSPG4), a molecule essential for OPC proliferation, migration, and myelination. In the absence of Abca8b, localization of CSPG4 to the plasma membrane was decreased, contributing to reduced cerebellar CSPG4 expression. Cerebellar CSPG4+ OPCs were also diminished, leading to decreased mature myelinating oligodendrocyte numbers and cerebellar myelination levels in Abca8b-/- mice. In addition, electron microscopy analyses showed that the number of nonmyelinated cerebellar axons was increased, whereas cerebellar myelin thickness (g-ratio), myelin sheath periodicity, and axonal diameter were all decreased, indicative of disordered myelin ultrastructure. In line with disrupted cerebellar myelination, Abca8b-/- mice showed lower cerebellar conduction velocity and disturbed locomotion. In summary, ABCA8 modulates cerebellar myelination, in part through functional regulation of the ABCA8-interacting protein CSPG4. Our findings suggest that ABCA8 disruption may contribute to the pathophysiology of myelin disorders.

Data resource profile: the Korea National Hospital Discharge In-depth Injury Survey.

The Korea National Hospital Discharge In-depth Injury Survey (KNHDIS), which was started in 2005, is a national probability survey of general hospitals in Korea with 100 or more beds conducted by the Korea Disease Control and Prevention Agency (KDCA). The KNHDIS captures approximately 9% of discharged cases from sampled hospitals using a 2-stage stratified cluster sampling scheme, among which 13% are injury related cases, defined as S00-T98 (injury, poisoning, and certain other consequences of external causes) using International Classification of Diseases, 10th revision codes. The KNHDIS collects information on characteristics of injury-related discharges in order to understand the scale of injuries, identify risk factors, and provide data supporting prevention policies and intervention strategies. The types of data captured include the hospitals' information, detailed clinical information, and injury-related codes such as the mechanism, activities undertaken when injured (sports, leisure activities, work, treatment, and education), external causes of the injury, and location of the occurrence of the injury based on the International Classification of External Causes of Injuries. Furthermore, the means of transportation, risk factors for suicide, and toxic substances are recoreded. Annual reports of the KNHDIS are publicly accessible to browse via the KDCA website (http://www.kdca.go.kr) and microdata are available free of charge upon request via email (kcdcinjury@korea.kr).

Dihydroceramide Desaturase Functions as an Inducer and Rectifier of Apoptosis: Effect of Retinol Derivatives, Antioxidants and Phenolic Compounds.

Dihydroceramide desaturase (Degs1) catalyses the introduction of a 4,5-trans double bond into dihydroceramide to form ceramide. We show here that Degs1 is polyubiquitinated in response to retinol derivatives, phenolic compounds or anti-oxidants in HEK293T cells. The functional predominance of native versus polyubiquitinated forms of Degs1 appears to govern cytotoxicity. Therefore, 4-HPR or celecoxib appear to stimulate the de novo ceramide pathway (with the exception of C24:0 ceramide), using native Degs1, and thereby promote PARP cleavage and LC3B-I/II processing (autophagy/apoptosis). The ubiquitin-proteasomal degradation of Degs1 is positively linked to cell survival via XBP-1s and results in a concomitant increase in dihydroceramides and a decrease in C24:0 ceramide levels. However, in the case of 4-HPR or celecoxib, the native form of Degs1 functionally predominates, such that the apoptotic programme is sustained. In contrast, 4-HPA or AM404 do not produce apoptotic ceramide, using native Degs1, but do promote a rectifier function to induce ubiquitin-proteasomal degradation of Degs1 and are not cytotoxic. Therefore, Degs1 appears to function both as an 'inducer' and 'rectifier' of apoptosis in response to chemical cellular stress, the dynamic balance for which is dependent on the nature of chemical stress, thereby determining cytotoxicity. The de novo synthesis of ceramide or the ubiquitin-proteasomal degradation of Degs1 in response to anti-oxidants, retinol derivatives and phenolic compounds appear to involve sensors, and for rectifier function, this might be Degs1 itself.

A new model for regulation of sphingosine kinase 1 translocation to the plasma membrane in breast cancer cells.

The translocation of sphingosine kinase 1 (SK1) to the plasma membrane (PM) is crucial in promoting oncogenesis. We have previously proposed that SK1 exists as both a monomer and dimer in equilibrium, although it is unclear whether these species translocate to the PM via the same or different mechanisms. We therefore investigated the structural determinants involved to better understand how translocation might potentially be targeted for therapeutic intervention. We report here that monomeric WT mouse SK1 (GFP-mSK1) translocates to the PM of MCF-7L cells stimulated with carbachol or phorbol 12-myristate 13-acetate, whereas the dimer translocates to the PM in response to sphingosine-1-phosphate; thus, the equilibrium between the monomer and dimer is sensitive to cellular stimulus. In addition, carbachol and phorbol 12-myristate 13-acetate induced translocation of monomeric GFP-mSK1 to lamellipodia, whereas sphingosine-1-phosphate induced translocation of dimeric GFP-mSK1 to filopodia, suggesting that SK1 regulates different cell biological processes dependent on dimerization. GFP-mSK1 mutants designed to modulate dimerization confirmed this difference in localization. Regulation by the C-terminal tail of SK1 was investigated using GFP-mSK1 truncations. Removal of the last five amino acids (PPEEP) prevented translocation of the enzyme to the PM, whereas removal of the last ten amino acids restored translocation. This suggests that the penultimate five amino acids (SRRGP) function as a translocation brake, which can be released by sequestration of the PPEEP sequence. We propose that these determinants alter the arrangement of N-terminal and C-terminal domains in SK1, leading to unique surfaces that promote differential translocation to the PM.

Shared reference materials harmonize lipidomics across MS-based detection platforms and laboratories.

Quantitative MS of human plasma lipids is a promising technology for translation into clinical applications. Current MS-based lipidomic methods rely on either direct infusion (DI) or chromatographic lipid separation methods (including reversed phase and hydrophilic interaction LC). However, the use of lipid markers in laboratory medicine is limited by the lack of reference values, largely because of considerable differences in the concentrations measured by different laboratories worldwide. These inconsistencies can be explained by the use of different sample preparation protocols, method-specific calibration procedures, and other experimental and data-reporting parameters, even when using identical starting materials. Here, we systematically investigated the roles of some of these variables in multiple approaches to lipid analysis of plasma samples from healthy adults by considering: 1) different sample introduction methods (separation vs. DI methods); 2) different MS instruments; and 3) between-laboratory differences in comparable analytical platforms. Each of these experimental variables resulted in different quantitative results, even with the inclusion of isotope-labeled internal standards for individual lipid classes. We demonstrated that appropriate normalization to commonly available reference samples (i.e., "shared references") can largely correct for these systematic method-specific quantitative biases. Thus, to harmonize data in the field of lipidomics, in-house long-term references should be complemented by a commonly available shared reference sample, such as NIST SRM 1950, in the case of human plasma.

Nutritional intake of pregnant women with gestational diabetes or type 2 diabetes mellitus.

Adequate intake of nutrients by pregnant women diagnosed with gestational diabetes mellitus (GDM) or type 2 diabetes (T2DM) is very important for appropriate weight gain and maintenance of normoglycemia without ketonuria. The aim of this study was to investigate the nutritional intake of pregnant women with GDM or T2DM who had not been provided with nutritional education regarding blood glucose management. Between June 2008 and May 2010, 125 pregnant women who had been diagnosed with GDM or T2DM and had not received any nutrition education regarding glycemic control and proper diet during pregnancy were interviewed to collect data regarding background characteristics, health-related behaviors, and course of pregnancy and instructed to record their dietary intake using a 24-hour recall method for one day. Using the collected data, the index of nutritional quality, nutrient adequacy ratio, and mean adequacy ratio values of the subjects were calculated. Analysis of the values indicated that the majority of the subjects did not meet recommended intake levels for most micronutrients and consumed an undesirable ratio of macronutrients, specifically a higher percentage of total carbohydrates than the current recommendation level. The GDM and T2DM groups obtained 56.6% and 63.6%, respectively (p = 0.012), of their calories by carbohydrate intake, which exceeded the recommended levels (125.8% in GDM groups, 141.3% in T2DM groups).

[Effects of Web-based health education on blood glucose and blood pressure improvement in postmenopausal women with impaired fasting blood glucose].

PURPOSE: The purpose of this study was to investigate the effectiveness of an educational intervention that used both cellular phones and the Internet to provide a short messaging service (SMS) relating to blood glucose, blood pressure, and serum lipid levels in postmenopausal women with impaired fasting glucose (IFG). METHODS: Twenty-eight postmenopausal women were assigned to an intervention group and twenty-one postmenopausal women to a control group. The intervention was provided for 12 weeks. Patients in the intervention group were asked to access a web site by using a cellular phone or to use the Internet directly and input their blood glucose and blood pressure levels weekly. Participants were sent the optimal recommendations weekly by both cellular phone and Internet. RESULTS: The intervention group had a mean decrease in systolic blood pressure (SBP) level of 8.1 mmHg but changes for the control group were not significant. There was a significant mean change in diastolic blood pressure (DBP) level for the intervention group (-7.7 mmHg). The mean change in the control group was not significant. CONCLUSION: This educational intervention using the Internet and a SMS by cellular phone improved levels of SBP and DBP in postmenopausal women with IFG.

Effects on diabetes management of a health-care provider mediated, remote coaching system via a PDA-type glucometer and the Internet.

We conducted a randomized controlled trial for 12 weeks in patients with type 2 diabetes living in a rural part of Korea. The intervention group (n = 35) was managed by a diabetes centre which provided specialized management mediated by a primary health-care nurse who used a PDA-type blood glucometer with a bar code detector to measure the capillary glucose levels. The control group (n = 36) received usual care. Compared with baseline, HbA(1c) was significantly reduced at three-month follow-up in the intervention group (8.0% vs. 7.5%; P < 0.01), but not in the control group. Total cholesterol was significantly reduced in the intervention group (10.7 mmol/L vs. 10.4 mmol/L; P = 0.043). Fasting plasma glucose and triglyceride levels were lower at follow-up in both groups, but the difference was not significant. The new system could be implemented widely and would contribute to improving the quality of diabetes care, even in isolated rural areas.

Ubiquitous Diabetes Management System via Interactive Communication Based on Information Technologies: Clinical Effects and Perspectives.

New diabetes management systems based on interactive communication have been introduced recently, accompanying rapid advances in information technology; these systems are referred to as "ubiquitous diabetes management systems." In such ubiquitous systems, patients and medical teams can communicate via Internet or telecommunications, with patients uploading their glucose data and personal information, and medical teams sending optimal feedback. Clinical evidence from both long-term and short-term trials has been reported by some researchers. Such systems appear to be effective not only in reducing the levels of HbA1c but also in stabilizing glucose control. However, most notably, evidence for the cost-effectiveness of such a system should be demonstrated before it can be propagated out to the general population in actual clinical practice. To establish a cost-effective model, various types of clinical decision supporting software designed to reduce the labor time of physicians must first be developed. A number of sensors and devices for monitoring patients' data are expected to be available in the near future; thus, methods for automatic interconnections between devices and web charts were also developed. Further investigations to demonstrate the clinical outcomes of such a system should be conducted, hopefully leading to a new paradigm of diabetes management.

Complication reducing effect of the information technology-based diabetes management system on subjects with type 2 diabetes.

OBJECTIVE: We introduced a new information technology-based diabetes management system, called the Internet-based glucose monitoring system (IBGMS), and demonstrated its short-term and long-term favorable effects. However, there has been no report on clinical effects of such a new diabetes management system on the development of diabetic complications so far. This study was used to simulate the complication reducing effect of the IBGMS, given in addition to existing treatments in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: The CORE Diabetes Model, a peer-reviewed, published, validated computer simulation model, was used to project long-term clinical outcomes in type 2 diabetes patients receiving the IBGMS in addition to their existing treatment. The model combined standard Markov submodels to simulate the incidence and progression of diabetes-related complications. RESULTS: The addition of IBGMS was associated with improvements in reducing diabetic complications, mainly microangiopathic complications, including diabetic retinopathy, diabetic neuropathy, diabetic nephropathy, and diabetic foot ulcer. The IBGMS also delayed the development of all diabetic complications for more than 1 year. CONCLUSIONS: This study demonstrated that the simulated IBGMS, compared to existing treatment, was associated with a reduction of diabetic complications. As a result, it provides valuable evidence for practical application to the public in the world.

Effects of nurse-coordinated intervention on patients with type 2 diabetes in Korea.

This study investigated the effects of a nurse-coordinated intervention on patients with type 2 diabetes in Korea. Fifteen patients were randomly assigned to an intervention group and 10 to a control group. The intervention was implemented for 12 weeks by telephone. Patients in the intervention group had a mean decrease of 1.2% in glycosylated hemoglobin (HbA(1C)) levels and those in the control group had a mean increase of 0.5%. Patients' satisfaction with care was higher in the intervention group than in the control group after the intervention. These findings indicated that the nurse-coordinated intervention could improve HbA(1C) levels and satisfaction with care in patients with type 2 diabetes in Korea.

Adherence to diabetes control recommendations: impact of nurse telephone calls.

BACKGROUND: Type 2 diabetes mellitus is increasing in incidence and research has shown that normalization of blood glucose levels can moderate the risk of microvascular and neurological complications. AIM: The purpose of this study was to investigate the effect of nurse telephone calls on glycosylated haemoglobin (HbA1c) levels and adherence to diabetes control recommendations. METHODS: A randomized design with control and experimental groups being assessed pre- and post intervention was used to assess the effectiveness of nurse telephone calls. Twenty patients were randomly assigned to an intervention group and 16 to a control group. The goal of the intervention was to keep blood glucose concentrations close to the normal range (HbA1c < 7%). The intervention was applied to the intervention group for 12 weeks, and consisted of continued education and reinforcement of diet, exercise, medication adjustment recommendations, as well as frequent self-monitoring of blood glucose levels. Telephone intervention was performed twice per week for the first month and then weekly for the second and third month. Participants were requested to write self-management logs including blood glucose levels, diet and an exercise diary. A dietitian analysed the diet diaries and participants were informed about their results by telephone or mail. All medication adjustments were communicated to participants' doctors. The HbA1c and diabetes adherence were measured before and after the intervention. RESULTS: Patients in the intervention group had a mean decrease of 1.2% in HbA1c levels and those in the control group had a mean increase of 0.6% in HbA1c levels. The intervention group had greater diet and blood glucose testing adherence than the control group. CONCLUSION: These findings indicate that a nurse telephone intervention can improve HbA1c, and diet and blood glucose testing adherence.

A telephone-delivered intervention to improve glycemic control in type 2 diabetic patients.

This study was performed to investigate the effect of a telephone-delivered intervention on glycemic control and body mass index in Korean type 2 diabetic patients. 38 patients were randomly selected, with 20 assigned to a telephone group and 18 to a control group. The goal of the intervention was to keep blood glucose concentrations close to the normal range. The intervention was applied to the telephone group for 12 weeks. It consisted of continuous education and reinforcement of diet, exercise and medication adjustment, as well as frequent self-monitoring of blood glucose levels. Telephone intervention was performed twice per week for the first month, and then weekly for the second and third months. Subjects were requested to write self- management logs, including blood glucose, diet and an exercise diary. The diet diaries were analyzed by a dietitian, and subjects instructed about the results by telephone counseling or mail. All medication adjustments were communicated to the subjects' diabetes specialist. Glycosylated hemoglobin (HbA1c), fasting blood glucose (FBG) and 2-hour postprandial glucose were measured before, and after, the intervention. Patients in the telephone group had a mean decrease of 1.2%, with those in the control group having a mean increase of 0.6%, in HbA1c. There were no significant differences in the body mass index (BMI) between the two groups. These findings indicated that a telephone-delivered intervention would improve HbA1c, but would not affect BMI.