Kidney stone matrix proteins:Role in stone formation

Stone formation is induced by an increased level of urine crystallization promoters and reduced levels of its inhibitors.Crystallization inhibitors include citrate,magnesium,zinc,and organic compounds such as glycosaminoglycans.In the urine,there are various proteins,such as uromodulin(Tamm-Horsfall protein),calgranulin,osteopontin,bikunin,and nephrocalcin,that are present in the stone matrix.The presence of several carboxyl groups in these macromolecules reduces calcium oxalate monohydrate crystal adhesion to the urinary epithelium and could potentially protect against lithiasis.Proteins are the most abundant component of kidney stone matrix,and their presence may reflect the process of stone formation.Many recent studies have explored the proteomics of urinary stones.Among the stone matrix proteins,the most frequently identified were uromodulin,S100 proteins(calgranulins A and B),osteopontin,and several other proteins typically engaged in inflammation and immune response.The normal level and structure of these macromolecules may constitute protection against calcium salt formation.Paradoxically,most of them may act as both promoters and inhibitors depending on circumstances.Many of these proteins have other functions in modulating oxidative stress,immune function,and inflammation that could also influence stone formation.Yet,the role of these kidney stone matrix proteins needs to be established through more studies comparing urinary stone proteomics between stone formers and non-stone formers.

Altered profiles of nuclear matrix proteins during the differentiation of human gastric mucous adenocarcinoma MGc80-3 cells

AIM： To find and identify specific nuclear matrix proteins associated with proliferation and differentiation of carcinoma cells, which will be potential markers for cancer diagnosis and targets in cancer therapy. METHODS： Nuclear matrix proteins were selectively extracted from MGcS0-3 cells treated with or without hexamethylamine bisacetamide （HMBA）, and subjected to 2-D gel electrophoresis. The resulted protein patterns were analyzed by Melanie software. Spots of nuclear matrix proteins differentially expressed were excised and subjected to in situ digestion with trypsin. Peptide masses were obtained by matrix-assisted laser-desorption/ ionization time of flight mass spectrometry （MALDI-TOFMS） analysis and submitted for database searching using Mascot tool. RESULTS： The MGc80-3 cells were induced into differentiation by HMBA. There were 22 protein spots which changed remarkably in the nuclear matrix, from differentiation of MGcS0-3 cells compared to control. Eleven of which were identified. Seven proteinsactin, prohibitin, porin 31HL, heterogeneous nuclear dbonucleoprotein A2/B1, vimentin, ATP synthase, and heat shock protein 60 were downregulated, whereas three proteins - heat shock protein gp96, heat shock protein 90-beta, and valosin-containing protein were upregulated, and the oxygen-regulated protein was only found in the differentiated MGc80-3 cells. CONCLUSION： The induced differentiation of carcinoma cells is accompanied by the changes of nuclear matrix proteins. Further characterization of those proteins will show the mechanism of cellular proliferation and differentiation, as well as cancer differentiation.

Induction of Bone Matrix Protein Expression by Native Bone Matrix Proteins in C2C12 Culture

Objective To study the expression of bone matrix protein （BMP） induced by bovine bone morphogenetic proteins （BMPs） in vitro. Methods Type 1 collagen, osteopontin （OPN）, osteonectin （ON）, osteocalcin （OC）, and bone sialoprotein （BSP） were detected by immunohistochemistry in C2C12 cultured from day 1 to day 28. Results The signaling of bone matrix protein expression became weaker except for type I collagen, OC and BSP after 5 days. Fourteen days after culture, the positive signaling of type I collagen, OPN, ON, OC, and BSP was gradually declined, and could be detected significantly as compared with that of the negative control on day 28. BMP assay showed that the lkaline phosphatase （ALP） activity was higher in C2C12 culture than in the control during the 14-day culture. Also, total protein and DNA significantly increased during the 14-day culture. High levels of ALP were seen in preosteoblasts and osteoblsts in vivo and in differentiating osteoblasts in vitro. ALP was well recognized as a marker reflecting osteoblastic activity. Conclusion Native bovine BMP induces conversion of myoblasts into osteoblasts, produces type I collagen, and plays significantly role in osteoinduction and bone matrix mineralization of C2C 12 in vitro.

The 5'-flanking cis-acting elements of the human ε-globin gene associates with the nuclear matrix and binds to the nuclear matrix proteins

The nucleax mains attachment regions(MARs) and the binding nuclear matrix proteins in the 5’-flalildng cisacting elements of the humanε-globin gene have been examined. Using in vitro DNA-matrix binding assay,it has been shown that the positive stage-specific regulatory element (ε-PREII, -446bp-419bp) upstream of this gene could specifically associate with the nuclear matrix from K562 cells, indicating thatε-PREII mad be an erythroidspecilic facultstive MAR. In gel mobility shift assay and Southwestern blotting assal an eothroid-specific nuclear matrix protein (ε-NMPk) in K562 cells has been revealed to bind to this positive regulatory element (E-PREII). Furthermore, we demonstrated that the silencer (-392hp -177bp) uP8tream of the humanε-globin gene could associate with the nuclear matrices from K562, HEL and Raji cells. In addition, the nucleax matrix proteins prepared from these three cell lines could also bind to this silencer, suggesting that this silencer element linght be a constitutive nuclear mains attachment region (constitutive MAR). Our results demonstrated that the nucleax madrid and nuclear mains proteins lxilght play an important role in the regulation of the human 5-globin gene expression.

Changes of β_3 Integrins and Extracellular Matrix Proteins in the Endometrium of Unexplained Infertility

The purpose of this study was to investigate changes of β 3 integrins and extra cellular matrix proteins including fibronectin (FN), laminin (LN) and collagen type Ⅳ (CL typeⅣ) on the endometrium of secretory phase from 31 fertile women (fertility group)and 34 women with unexplained infertility (infertility group) by a histochemical method.The results were as follows:In glandular epithelium, β 3 integrin appeared in the mid secretory phase and continued to late secretory phase in the fertility group, but was not expressed during the secretory phase in the infertility group. Extracellular matrix proteins from the fertility group were expressed more strongly in mid secretory phase than that in the early secretory phase, and were weakest in the late secretory phase. Compared with the fertility group, the levels of extracellular matrix proteins in the infertility group were elevated in the secretory phase. In conclusion: our current study demonstrate that β 3 integrin and extracellular matrix proteins are expressed at different levels in the endometrium during the menstrual cycle. They are involved in endometrial changes during the menstrual cycle and during the implantation of the blastocyst. Their unusual expression result in the failure of implantation.

STUDY ON NUCLEAR MATRIX PROTEINS FROM HUMAN BREAST CARCINOMA

Objective To investigate the marker protein of human breast carcinoma from nuclear matrix proteins (NMPs). Methods NMPs were injected subcutaneously into rabbit to get antiserum, which was used to detect the NMPs specificity for breast carcinoma. Results There was an apparent positive band (100 kD) in the NMPs of breast carcinoma, which did not exist in normal breast and other tumors that were detected.Conclusion One or one group of 100 kD NMPs were found to be related to human breast carcinoma, which may be involved in the carcinogenesis and development of human breast carcinoma and valuable for breast carcinoma diagnosis.

Alreration of nuclear matrix-intermediate filament system and differential expression of nuclear matrix proteins during human hepatocarcinoma cell differentiation

AIM： To investigate the association between the configurational and compositional changes of nuclear matrix and the differentiation of carcinoma cells. METHODS： Cells cultured with or without 5 × 10^-3 mmol/L of hexamethylene bisacetamide （HMBA） on Nickel grids were treated by selective extraction and prepared for whole mount observation under electron microscopy. The samples were examined under transmission electron microscope. Nuclear matrix proteins were selectively extracted and subjected to subcellular proteomics study. The protein expression patterns were analyzed by PDQuest software. Spots of differentially expressed nuclear matrix proteins were excised and subjected to in situ digestion with trypsin. The peptides were analyzed by matrix-assisted laser- desorption/ionization time of flight mass spectrometry （MALDI-TOF-MS）. Data were submitted for database searching using Mascot tool （www.matrixscience.com）. RESULTS： The nuclear matrix （NM） and intermediate filament （IF） in SMMC-7721 hepatocarcinoma cells were found relatively sparse and arranged irregularly. The nuclear lamina was non-uniform, and two kinds of filaments were not tightly connected. After induction for differentiation by HMBA, the NM-IF filaments were concentrated and distributed uniformly. The heterogeneous population of filaments, including highly branched utrathin filaments could also be seen in the regular meshwork. The connection between the two kinds of filaments and the relatively thin, condensed and sharply demarcated lamina composed of intermediate- sized filaments was relatively fastened. Meanwhile, 21 NM proteins changed remarkably during SMMC-7721 cell differentiation. Four proteins, i.e. mutant Pystl, hypothetical protein, nucleophosminl, and LBP were downregulated, whereas four other proteins, eIF6, p44 subunit, 13-tubulin, and SIN3B were upregulated with the last one, SR2/ASF found only in the differentiated SMMC-7721 cells. CONCLUSION： The induced differentiation of SMMC-7721 cells by HMBA is accompanied by the configurational changes of nuclear matrix-intermediate filament （NM-IF） system and the compositional changes of nuclear matrix protein expression. These changes may be important morphological or functional indications of the cancer cell reversion.

Enamel matrix proteins in promoting saliva lubrication

Anti-wear performance of human enamel in the mouth is closely related to the lubrication of salivary pellicle.It is well known that the inorganic hydroxyapatite(HA)of the enamel plays an important role in the adsorption and pellicle-forming of salivary proteins on the enamel,but the role of enamel matrix proteins remains unclear.In this study,the adsorption and lubrication behavior of salivary proteins on original,heated,and deproteinated enamel surfaces was comparatively investigated using an atomic force microscopy and nano-indentation/scratch techniques.Compared with that on the original enamel surface,the adsorption and lubrication behavior of salivary proteins remains almost unchanged on the heated enamel surface(where the enamel matrix proteins are denatured but the size of HA crystalline nanoparticles keeps constant)but exhibits an obvious compromise on the deproteinated enamel surface(where the enamel matrix proteins are removed and agglomeration of HA crystallites occurs).The HA agglomeration weakens the electrostatic interaction of enamel surfaces with salivary proteins to cause a distinct negative influence on the adsorption and pellicle-forming of salivary proteins.Further,the negative effect is confirmed with a quartz crystal microbalance with dissipation.In summary,by regulating enamel nanostructure for appropriate electrostatic interactions between salivary proteins and enamel surfaces,the enamel matrix proteins play an essential role in the adsorption and pellicle-forming of salivary proteins on human enamel,and then contribute to saliva lubrication,which provides the enamel with an anti-wear mechanism.The findings will promote and assist the design of enamel-inspired anti-wear materials.

Changes of Nuclear Matrix Proteins Following the Differentiation of Human Osteosarcoma MG-63 Cells

Human osteosarcoma MG-63 cells were induced into differentiation by 5 mmol/L hexamethylene bisacetamide （HMBA）. Their nuclear matrix proteins （NMPs） were selectively extracted and subjected to two-dimensional gel electrophoresis analysis. The results of protein patterns were analyzed by Melanie software. The spots of differentially expressed NMPs were excised and subjected to in situ digestion with trypsin. The maps of peptide mass fingerprinting were obtained by MALDI-TOF-MS analysis, and were submitted for NCBI database searches by Mascot tool. There were twelve spots changed remarkably during the differentiation induced by HMBA, nine of which were identified. The roles of the regulated proteins during the MG-63 differentiation were analyzed. This study suggests that the induced differentiation of cancer cells is accompanied by the changes of NMPs, and confirms the presence of some specific NMPs related to the cancer cell proliferation and differentiation. The changed NMPs are potential markers for cancer diagnosis or targets for cancer therapy.

Comparative proteomic analysis of extracellular matrix proteins secreted by hypertrophic scar witb normal skin fibroblasts

The formation of hypertrophic scars (HSs) is a fibroproliferative disorder of abnormal wound healing. HSs usually characterize excessive proliferation of fibroblasts, abnormal deposition of extracellular matrix (ECM) during wound healing, associated with cosmetic, functional, and psychological problems. Owing to the role of ECM proteins in scar formation, we comparatively analyzed matrix proteins secreted by normal skin fibroblasts (NSFs) and HS fibroblasts (HSFs). The acetone-extracted secreted proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and identified by mass spectrometry (MS). Based on Go annotation of MS data, the profiling of ECM proteins was established and scar-related proteins have been screened out. The functions of several ECM proteins identified by MS have been discussed, such as collagens I, VI, XII, fibronectin, decorin, lumican, and protein procollagen C endopeptidase enhancer 1 (PCPE-1). Among them, the MS result of PCPE-1 was supported by Western blotting that PCPE-1 from HSFs were significantly upregulated than that from NSFs. It is suggested that PCPE-1 could be a potential target for scar treatment. The exploration of scar related proteins may provide new perspectives on understanding the mechanism of scar formation and open a new way to scar treatment and prevention.

Interactions between the nuclear matrix proteins and the 5'-flanking cis-acting elements of the human ε-globin gene

An erythroid-specific nuclear matrix protein (termed ε-NMP_k) in K562 cells, which can specifically bind to the positive stage-specific regulatory element (ε-PRE Ⅱ, -446—-419 bp) upstream of the human ε-globin gene, has been identified by using gel mobility shift assay.Meanwhile, Southwestern blotting assay showed that the nuclear matrix protein ε-NMP_k in K562,cells may be composed of two polypeptides ( ～ 40 ku). In addition, it is observed in the gel mobility shift assay that the nuclear matrix proteins from K562, HEL and Raji cells can bind to the silencer DNA ( - 392— -177 bp) in the 5’-flanking sequence of human ε-globin gene respectively. However, the shift band K detected in K562 cells is different from shift band H/R in HEL and Raji cells, suggesting that a common nuclear matrix protein may exist in HEL and Raji cells. Results show that the nuclear matrix protein may play an important role in the regulation of the human ε-globin gene expression.

Aberrant expression of genes and proteins in pterygium and their implications in the pathogenesis

Pterygium is a common ocular surface disease induced by a variety of factors. The exact pathogenesis of pterygium remains unclear. Numbers of genes and proteins are discovered in pterygium and they function differently in the occurrence and development of this disease. We searched the Web of Science and PubMed throughout history for literatures about the subject. The keywords we used contain pterygium, gene, protein, angiogenesis, fibrosis, proliferation, inflammation, pathogenesis and therapy. In this review, we summarize the aberrant expression of a range of genes and proteins in pterygium compared with normal conjunctiva or cornea, including growth factors, matrix metalloproteinases and tissue inhibitors of mefalloproteinases, interleukins, tumor suppressor genes, proliferation related proteins, apoptosis related proteins, cell adhesion molecules, extracellular matrix proteins, heat shock proteins and tight junction proteins. We illustrate their possible mechanisms in the pathogenesis of pterygium as well as the related intervention based on them for pterygium therapy.

The interaction between the human β-globin locus control region and nuclear matrix

Our previous study showed that hydroxyurea (Hu) could induce HEL cells to express humanβ-globin gene. However the molecular mechanisms by which the expression of β-globin gene is activated and regulated are poorly understood. Here we show that the binding patterns between the core DNA sequences (HS2 core sequence -10681- -10971 bp , HS3 core sequence -14991- -14716 bp and HS4 core sequence -18586- -18306 bp) of DNase I hypersensitive sites in the human β-globin LCR and nuclear matrix proteins isolated from Hu induced and uninduced HEL cells are quite different. Results demonstrated that nuclear matrix proteins might play important roles in regulating the expression of humanβ-like globin genes through their interaction with HSs (HS2,HS3 and HS4 core sequences) in the LCR. Moreover, the results obtained from the in vitro DNA-matrix binding assay showed that the core DNA sequences of DNase I hypersensitive sites (HS2, HS3 and HS4) were unable to bind to the nuclear matrix isolated from uninduced HEL cells; in addition, HS2 core DNA sequence was capable of binding to the nuclear matrix prepared from Hu-induced HEL cells, while both HS3 and HS4 core DNA sequences could not do so. Results indicated that the HS2 core DNA sequence may be a functional MAR (matrix attachment region). We suggest that the HS2 core DNA sequence binding to the nuclear matrix in Hu-induced HEL cells may open the structure of chromatin to make the LCR accessible to the promoter of β-globin gene and to promote its transcription.

NUCLEAR MATRIX PROTEIN IN LEUKEMIA CELLS

Objective: To compare the composition of nuclear matrix proteins (NMP) between leukemia cells and normal bone marrow cells. Methods: NMP was isolated by high-salt extraction and identified in acute and chronic myelogenous leukemia cells as well as in the blast phase of chronic leukemia. On SDS-PAGE, NMPs with molecular myelogenous ferment from what were seen in normal bone marrow cells were present in both acute and chronic myelogenous leukemia. Conclusion: Marked changes of NMP, not only in contents but also in compositions, exist in leukemic cells compared with normal bone marrow cells. NMP may serve as a target of chemotherapeutic drug against leukemia.

Altered serum level of cartilage oligomeric matrix protein and its association with coronary calcification in patients with coronary heart disease

Background Cartilage oligomeric matrix protein （COMP） is mainly found in the skeletal system and vascular smooth muscle cells. Recent researches showed that it had a protective function on blood vessels and could also inhibit vascular calcification. We investigated the serum COMPs in coronary heart disease （CHD） patients, and the relationship between serum COMP and the calcification of coronary artery. Methods A total of 233 consecutive chest pain patients who first underwent coronary angiography followed by multi-slice computed to- mography （MSCT） within six months were recruited and divided into two groups according to the coronary angiography luminal diameter narrowing percentages： CHD group （diameter narrowing 〉 50%, n = 194） and control group （diameter narrowing 〈 50%, n = 39）. The Gen- sini score, Syntax score and coronary artery calcium score （CACs） were calculated. The serum COMP level was determined using ELISA. Results The levels of COMP were significantly higher in the CHD group than in the control group 155.7 （124.5-194.5） ng/mL vs. 128.4 （113.0-159.9） ng/mL, P = 0.019. There were no correlation between COMP, Gensini score, Syntax score, severity of coronary stenosis and the number of coronary artery with stenosis 〉 50%. The serum COMP was correlated with age （r = 0.294, P 〈 0.001）, fasting glucose （r = 0.163, P = 0.015）, HbAlc （r = 0.194, P = 0.015） and CACs （r = 0.137, P = 0.037）. Stepwise linear regression analysis showed that COMP level and age were independent predictors of CACs in the CHD patients （fl = 0.402, t = 2.612, P = 0.015; fl = 0.472, t = 3.077, P = 0.005）. Performance of COMP for predicting CHD was shown as area under curve （AUC）： 0.632, 95% CI： 0.549-0.715 and upper tertile CACs was AUC： 0.602, 95% CI： 0.5264）.678 in receiver operating characteristic （ROC） curve analysis. Conclusion Calcification of coronary artery was an independent predictor of serum COMPs.

Association between serum cartilage oligomeric matrix protein and coronary artery calcification in maintenance hemodialysis patients

Background Coronary artery calcification(CAC)is common in end-stage renal disease(ESRD)patients,and the extent of CAC is closely related to cardiovascular outcomes in ESRD patients.Cartilage oligomeric matrix protein(COMP),as a component of the vascular matrix,has been found to be an inhibitor of arterial calcification in basic studies.However,there is no clinical research on the correlation between COMP and CAC in maintenance hemodialysis(MHD)patients.The aim of this study was to explore the relationship between serum COMP levels and CAC and cardiovascular events in MHD patients.Methods Serum COMP levels were compared between 54 MHD patients and 66 healthy people.MHD patients were then divided into three groups according to the tertiles of the concentration of COMP level and were followed up for major adverse cardiac events(MACEs),which were defined as a combined end point of new onset angina pectoris,nonfatal myocardial infarction,heart failure,coronary artery revascularization,hospitalization due to angina pectoris and all-cause deaths.The CAC score was calculated based on computed tomography scans.Results The serum COMP level in MHD patients was significantly higher than that in the general population[984.23(248.43-1902.61)ng/mL vs.219.01(97.26-821.92)ng/mL,P<0.01].Serum COMP levels were positively correlated with CAC(r=0.313,P=0.021)and serum parathyroid hormone in MHD patients(r=0.359,P<0.01).Linear regression suggested that after adjusting for age,fasting blood glucose(Glu)and glycosylated hemoglobin(HbAlc),CAC score was an independent predictor in the final model for COMP level(β=0.424,t=3.130,P<0.01).The receiver operating characteristic(ROC)curve showed that COMP≥994 mg/mL had 68.0%sensitivity and 72.4%specificity for the prediction of severe CAC[area under the curve(AUC):0.674,P=0.030,95%CI:0.526-0.882].After a median follow-up of 16 months(8-24 months),there was no difference in the incidence rate of MACEs between the upper,middle and lower serum COMP groups.Conclusions Our study found that MHD patients have higher levels of circulating COMP than controls.The serum COMP level is positively correlated with CAC score and could be used as a biomarker of severe CAC in MHD patients.However,there is no obvious correlation between serum COMP levels and the incidence of cardiovascular events.

Comparisons of voided urine cytology, nuclear matrix protein-22 and bladder tumor associated antigen tests for bladder cancer of geriatric male patients in Taiwan, China

Aim： To compare the results of bladder tumor associated antigen （BTA TRAK）, nuclear matrix protein 22 （NMP 22） and voided urine cytology （VUC） in detecting bladder cancer. Methods： A total of 135 elderly male and 50 healthy volunteers enrolled in this study were classified into three groups： （i） 93 patients with bladder cancer; （ii） 42 patients with urinary benign conditions; and （iii） 50 healthy volunteers. BTA TRAK and NMP 22 kits were used to detect bladder cancer. Voided urine cytology was used to compare the sensitivity and specificity of the screening tests. Results： The sensitivity and specificity of cytology, BTA TRAK and NMP 22 were 24% and 97%, 51% and 73%, 78% and 73%, respectively. The level of NMP 22 increased with tumor grading. The BTA TRAK kit has the lowest sensitivity among the screening tests. The NMP 22 with the best sensitivity can be an adjunct to cytology for evaluating bladder cancer. Conclusion： The NMP 22 test has a better correlation with the grading of the bladder cancer than BTA TRAK. As cytology units are typically not available in hospitals or in outpatient clinics, NMP 22 might be a promising tool for screening bladder cancer.

Inactive matrix Gla protein is elevated in patients with inflammatory bowel disease

BACKGROUND Matrix Gla protein(MGP)is a vitamin K dependent peptide which has an established role in suppression of vascular calcification.Recent studies have pointed to a possible link between immunomodulatory effect of MGP and inflammatory bowel disease(IBD).AIM To compare plasma levels of dephosphorylated and uncarboxylated MGP(dpucMGP)between IBD patients and controls.METHODS This cross-sectional study was conducted on 70 patients with IBD(30 patients with ulcerative colitis and 40 patients with Crohn’s disease)and 60 age and gender matching healthy controls.Plasma dp-ucMGP levels were analyzed from blood samples by CLIA method using IDS-iSYS InaKtif MGP(Immunodiagnostic Systems,Frankfurt,Germany)according to the manufacturer's instructions.fecal calprotectin(FC)levels were determined from stool samples by turbidimetric immunoassay method using Bühlmann fecal calprotectin turbo assay(Bühlmann Laboratories Aktiengesellschaft,Schonenbuch,Switzerland).Other parameters were analyzed according to the standard laboratory procedures.RESULTS Plasma levels of dp-ucMGP were significantly higher in patients with IBD compared to the healthy control group(629.83±124.20 pmol/mL vs 546.7±122.09 pmol/mL,P<0.001),and there was no significant difference between patients with Crohn’s disease and patients with ulcerative colitis(640.02±131.88 pmol/mL vs 616.23±113.92 pmol/mL,P=0.432).Furthermore,a significant positive correlation of plasma dp-ucMGP levels was found with both FC levels(r=0.396,P<0.001)and high sensitivity C-reactive protein(hsCRP)levels(r=0.477,P<0.001).Moreover,in the total study population a significant positive correlation was found between dp-ucMGP with age(r=0.210,P=0.016)and waist circumference(r=0.264,P=0.002).Multiple linear regression analysis showed that dp-ucMGP levels retained significant association with FC(β±SE,0.06±0.02,P=0.003).CONCLUSION Study results support experimental data of MGP immunomodulatory IBD effect and indicate potential involvement in the pathophysiology of the disease,and possibly extraintestinal manifestations.

Dentin matrix protein 1 and phosphate homeostasis are critical for postnatal pulp, dentin and enamel formation

Deletion or mutation of dentin matrix protein 1 （DMP1） leads to hypophosphatemic rickets and defects within the dentin. However, it is largely unknown if this pathological change is a direct role of DMP1 or an indirect role of phosphate （Pi） or both. It has also been previously shown that Klotho-deficient mice, which displayed a high Pi level due to a failure of Pi excretion, causes mild defects in the dentinal structure. This study was to address the distinct roles of DMP1 and Pi homeostasis in cell differentiation, apoptosis and mineralization of dentin and enamel. Our working hypothesis was that a stable Pi homeostasis is critical for postnatal tooth formation, and that DMP1 has an antiapoptotic role in both amelogenesis and dentinogenesis. To test this hypothesis, Dmpl-null （Dmpl-/-）, Klotho-deficient （kl/kl）, Dmpl/Klotho-double-deficient （Dmpl-/-/kl/kl） and wild-type （WT） mice were killed at the age of 6 weeks. Combinations of X-ray, microcomputed tomography （I^CT）, scanning electron microscopy （SEM）, histology, apoptosis and immunohistochemical methods were used for characterization of dentin, enamel and pulp structures in these mutant mice. Our results showed that Dmpl-/- （a low Pi level） or kl/kl（a high Pi level） mice displayed mild dentin defects such as thin dentin and a reduction of dentin tubules. Neither deficient mouse line exhibited any apparent changes in enamel or pulp structure. However, the double-deficient mice （a high Pi level） displayed severe defects in dentin and enamel structures, including loss of dentinal tubules and enamel prisms, as well as unexpected ectopic ossification within the pulp root canal. TUNEL assay showed a sharp increase in apoptotic cells in ameloblasts and odontoblasts. Based on the above findings, we conclude that DMP1 has a protective role for odontoblasts and ameloblasts in a pro-apoptotic environment （a high Pi level）.

Significance of serum glucagon-like peptide-1 and matrix Gla protein levels in patients with diabetes and osteoporosis

BACKGROUND Osteoporosis is a systemic bone disease characterized by decreased bone mass,impaired bone mass,and reduced bone strength that leads to increased bone fragility and fracture.Type 2 diabetes mellitus(T2DM)complicated with osteoporosis is a common systemic metabolic bone disease,and reduced bone mass and bone strength are considered the main clinical features;however,the pathogenesis of this disease has not been fully clarified.Its occurrence is considered related to sex,age,and genetic factors.There are many risk factors for diabetes complicated with osteoporosis.Therefore,exploring these risk factors will help prevent it.AIM To investigate the relationships among serum glucagon-like peptide-1(GLP-1)levels,matrix Gla protein(MGP)levels,and diabetes with osteoporosis.METHODS Sixty patients with T2DM complicated with osteoporosis confirmed by the endocrinology department of our hospital were selected as the case group.Sixty T2DM patients with bone loss were selected as the control group.Sixty healthy participants were selected as the healthy group.The general data,bone mineral density index,and bone metabolic markers of the three groups were compared.The relationships among GLP-1 levels,MGP levels,and the bone mineral density index of the case group were analyzed using linear correlation analysis and a logistic regression model.RESULTS Differences in sex,smoking,and drinking among the case group,control group,and healthy group were not statistically significant(P>0.05).The mean age of the case group was older than those of the control and healthy groups(P<0.05).The body mass index,fasting plasma glucose level,HbA1c level,hypertension rate,and coronary heart disease rate of the case and control groups were higher than those of the healthy group(P<0.05).The serum GLP-1 and MGP levels of the case group were lower than those of the control and healthy groups;these differences were statistically significant(P<0.05).The serum GLP-1 and MGP levels of the control group were lower than those of the healthy group;these differences were statistically significant(P<0.05).The serum GLP-1 and MGP levels of the case group were significantly positively correlated with the bone mineral density values of the hip and lumbar spine(P<0.05).The results of the logistic regression model showed that age and duration of diabetes were independent risk factors for osteoporosis in diabetic patients(P<0.05)and that increased GLP-1 and MGP values were protective factors against osteoporosis in diabetic patients(P<0.05).CONCLUSION Serum GLP-1 and MGP levels of diabetic patients with osteoporosis were significantly decreased and positively correlated with bone mineral density and were independent risk factors for osteoporosis in diabetic patients.