TNAP upregulation is a critical factor in Tauopathies and its blockade ameliorates neurotoxicity and increases life-expectancy.

Tauopathies are a family of neurodegenerative diseases characterized by the presence of abnormally hyperphosphorylated Tau protein. Several studies have proposed that increased extracellular Tau (eTau) leads to the spread of cerebral tauopathy. However, the molecular mechanisms underlying eTau-induced neurotoxicity remain unclear. Previous in vitro studies reported that the ecto-enzyme tissue-nonspecific alkaline phosphatase (TNAP) dephosphorylate eTau at different sites increasing its neurotoxicity. Here, we confirm TNAP protein upregulation in the brains of Alzheimer's patients and found a similar TNAP increase in Pick's disease patients and P301S mice, a well-characterized mouse model of tauopathies. Interestingly, the conditional overexpression of TNAP causes intracellular Tau hyperphosphorylation and aggregation in cells neighbouring those overexpressing the ectoenzyme. Conversely, the genetic disruption of TNAP reduced the dephosphorylation of eTau and decreased neuronal hyperactivity, brain atrophy, and hippocampal neuronal death in P301S mice. TNAP haploinsufficiency in P301S mice prevents the decreased anxiety-like behaviour, motor deficiency, and increased memory capacity and life expectancy. Similar results were observed by the in vivo pharmacological blunting of TNAP activity. This study provides the first in vivo evidence demonstrating that raised TNAP activity is critical for Tau-induced neurotoxicity and suggest that TNAP blockade may be a novel and efficient therapy to treat tauopathies.

Mitochondrial TNAP controls thermogenesis by hydrolysis of phosphocreatine.

Adaptive thermogenesis has attracted much attention because of its ability to increase systemic energy expenditure and to counter obesity and diabetes1-3. Recent data have indicated that thermogenic fat cells use creatine to stimulate futile substrate cycling, dissipating chemical energy as heat4,5. This model was based on the super-stoichiometric relationship between the amount of creatine added to mitochondria and the quantity of oxygen consumed. Here we provide direct evidence for the molecular basis of this futile creatine cycling activity in mice. Thermogenic fat cells have robust phosphocreatine phosphatase activity, which is attributed to tissue-nonspecific alkaline phosphatase (TNAP). TNAP hydrolyses phosphocreatine to initiate a futile cycle of creatine dephosphorylation and phosphorylation. Unlike in other cells, TNAP in thermogenic fat cells is localized to the mitochondria, where futile creatine cycling occurs. TNAP expression is powerfully induced when mice are exposed to cold conditions, and its inhibition in isolated mitochondria leads to a loss of futile creatine cycling. In addition, genetic ablation of TNAP in adipocytes reduces whole-body energy expenditure and leads to rapid-onset obesity in mice, with no change in movement or feeding behaviour. These data illustrate the critical role of TNAP as a phosphocreatine phosphatase in the futile creatine cycle.

Quantitative atomic force microscopy provides new insight into matrix vesicle mineralization.

Matrix vesicles (MVs) are a class of extracellular vesicles that initiate mineralization in cartilage, bone, and other vertebrate tissues by accumulating calcium ions (Ca2+) and inorganic phosphate (Pi) within their lumen and forming a nucleation core (NC). After further sequestration of Ca2+ and Pi, the NC transforms into crystalline complexes. Direct evidence of the existence of the NC and its maturation have been provided solely by analyses of dried samples. We isolated MVs from chicken embryo cartilage and used atomic force microscopy peak force quantitative nanomechanical property mapping (AFM-PFQNM) to measure the nanomechanical and morphological properties of individual MVs under both mineralizing (+Ca2+) and non-mineralizing (-Ca2+) fluid conditions. The elastic modulus of MVs significantly increased by 4-fold after incubation in mineralization buffer. From AFM mapping data, we inferred the morphological changes of MVs as mineralization progresses: prior to mineralization, a punctate feature, the NC, is present within MVs and this feature grows and stiffens during mineralization until it occupies most of the MV lumen. Dynamic light scattering showed a significant increase in hydrodynamic diameter and no change in the zeta potential of hydrated MVs after incubation with Ca2+. This validates that crystalline complexes, which are strongly negative relative to MVs, were forming within the lumen of MVs. These data were substantiated by transmission electron microscopy energy dispersive X-ray and Fourier transform infrared spectroscopic analyses of dried MVs, which provide evidence that the complexes increased in size, crystallinity, and Ca/P ratio within MVs during the mineralization process.

Non-targeted profiling of circulating microRNAs in women with polycystic ovary syndrome (PCOS): effects of obesity and sex hormones.

PURPOSE: Circulating micro-ribonucleic acids (miRNAs) are small noncoding RNA molecules that influence gene transcription. We conducted the present profiling study to characterize the expression of circulating miRNAs in lean and obese patients with polycystic ovary syndrome (PCOS), the most common endocrine and metabolic disorder in premenopausal women. BASIC PROCEDURES: We selected 11 control women, 12 patients with PCOS and 12 men so that they were similar in terms of body mass index. Five control women, 6 men and 6 patients with PCOS had normal weight whereas 6 subjects per group were obese. We used miRCURY LNA™ Universal RT microRNA PCR for miRNA profiling. MAIN FINDINGS: The expression of 38 miRNAs and was different between subjects with PCOS and male and female controls. The differences in 15 miRNAs followed a pattern suggestive of androgenization characterized by expression levels that were similar in patients with PCOS and men but were different compared with those of control women. The expression of 13 miRNAs in women with PCOS was similar to that of control women and different compared with the expression observed in men, suggesting sexual dimorphism and, lastly, we observed 5 miRNAs that were expressed differently in women with PCOS compared with both men and control women, suggesting a specific abnormality in expression associated with the syndrome. Obesity interacted with the differences in several of these miRNAs, and the expression levels of many of them correlated with the hirsutism score, sex hormones and/or indexes of obesity, adiposity and metabolic dysfunction. PRINCIPAL CONCLUSIONS: The present results suggest that several serum miRNAs are influenced by PCOS, sex hormones and obesity. Our findings may guide the targeted search of miRNAs as clinically relevant markers for PCOS and its association with obesity and metabolic dysfunction in future studies.

Inhibition of arterial medial calcification and bone mineralization by extracellular nucleotides: The same functional effect mediated by different cellular mechanisms.

Arterial medial calcification (AMC) is thought to share some outward similarities to skeletal mineralization and has been associated with the transdifferentiation of vascular smooth muscle cells (VSMCs) to an osteoblast-like phenotype. ATP and UTP have previously been shown to inhibit bone mineralization. This investigation compared the effects of extracellular nucleotides on calcification in VSMCs with those seen in osteoblasts. ATP, UTP and the ubiquitous mineralization inhibitor, pyrophosphate (PPi ), dose dependently inhibited VSMC calcification by ≤85%. Culture of VSMCs in calcifying conditions was associated with an increase in apoptosis; treatment with ATP, UTP, and PPi reduced apoptosis to levels seen in non-calcifying cells. Extracellular nucleotides had no effect on osteoblast viability. Basal alkaline phosphatase (TNAP) activity was over 100-fold higher in osteoblasts than VSMCs. ATP and UTP reduced osteoblast TNAP activity (≤50%) but stimulated VSMC TNAP activity (≤88%). The effects of extracellular nucleotides on VSMC calcification, cell viability and TNAP activity were unchanged by deletion or inhibition of the P2Y2 receptor. Conversely, the actions of ATP/UTP on bone mineralization and TNAP activity were attenuated in osteoblasts lacking the P2Y2 receptor. Ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) hydrolyses ATP and UTP to produce PPi . In both VSMCs and osteoblasts, deletion of NPP1 blunted the inhibitory effects of extracellular nucleotides suggesting involvement of P2 receptor independent pathways. Our results show that although the overall functional effect of extracellular nucleotides on AMC and bone mineralization is similar there are clear differences in the cellular mechanisms mediating these actions.

Intravesicular Phosphatase PHOSPHO1 Function in Enamel Mineralization and Prism Formation.

The transport of mineral ions from the enamel organ-associated blood vessels to the developing enamel crystals involves complex cargo packaging and carriage mechanisms across several cell layers, including the ameloblast layer and the stratum intermedium. Previous studies have established PHOSPHO1 as a matrix vesicle membrane-associated phosphatase that interacts with matrix vesicles molecules phosphoethanolamine and phosphocholine to initiate apatite crystal formation inside of matrix vesicles in bone. In the present study, we sought to determine the function of Phospho1 during amelogenesis. PHOSPHO1 protein localization during amelogenesis was verified using immunohistochemistry, with positive signals in the enamel layer, ameloblast Tomes' processes, and in the walls of ameloblast secretory vesicles. These ameloblast secretory vesicle walls were also labeled for amelogenin and the exosomal protein marker HSP70 using immunohistochemistry. Furthermore, PHOSPHO1 presence in the enamel organ was confirmed by Western blot. Phospho1-/- mice lacked sharp incisal tips, featured a significant 25% increase in total enamel volume, and demonstrated a significant 2-fold reduction in silver grain density of von Kossa stained ground sections indicative of reduced mineralization in the enamel layer when compared to wild-type mice (p < 0.001). Scanning electron micrographs of Phospho1-/- mouse enamel revealed a loss of the prominent enamel prism "picket fence" structure, a loss of parallel crystal organization within prisms, and a 1.56-fold increase in enamel prism width (p < 0.0001). Finally, EDS elemental analysis demonstrated a significant decrease in phosphate incorporation in the enamel layer when compared to controls (p < 0.05). Together, these data establish that the matrix vesicle membrane-associated phosphatase PHOSPHO1 is essential for physiological enamel mineralization. Our findings also suggest that intracellular ameloblast secretory vesicles have unexpected compositional similarities with the extracellular matrix vesicles of bone, dentin, and cementum in terms of vesicle membrane composition and intravesicular ion assembly.

Biophysical aspects of biomineralization.

During the process of endochondral bone formation, chondrocytes and osteoblasts mineralize their extracellular matrix (ECM) by promoting the synthesis of hydroxyapatite (HA) seed crystals in the sheltered interior of membrane-limited matrix vesicles (MVs). Several lipid and proteins present in the membrane of the MVs mediate the interactions of MVs with the ECM and regulate the initial mineral deposition and posterior propagation. Among the proteins of MV membranes, ion transporters control the availability of phosphate and calcium needed for initial HA deposition. Phosphatases (orphan phosphatase 1, ectonucleotide pyrophosphatase/phosphodiesterase 1 and tissue-nonspecific alkaline phosphatase) play a crucial role in controlling the inorganic pyrophosphate/inorganic phosphate ratio that allows MV-mediated initiation of mineralization. The lipidic microenvironment can help in the nucleation process of first crystals and also plays a crucial physiological role in the function of MV-associated enzymes and transporters (type III sodium-dependent phosphate transporters, annexins and Na+/K+ ATPase). The whole process is mediated and regulated by the action of several molecules and steps, which make the process complex and highly regulated. Liposomes and proteoliposomes, as models of biological membranes, facilitate the understanding of lipid-protein interactions with emphasis on the properties of physicochemical and biochemical processes. In this review, we discuss the use of proteoliposomes as multiple protein carrier systems intended to mimic the various functions of MVs during the initiation and propagation of mineral growth in the course of biomineralization. We focus on studies applying biophysical tools to characterize the biomimetic models in order to gain an understanding of the importance of lipid-protein and lipid-lipid interfaces throughout the process.

Topographic analysis by atomic force microscopy of proteoliposomes matrix vesicle mimetics harboring TNAP and AnxA5.

Atomic force microscopy (AFM) is one of the most commonly used scanning probe microscopy techniques for nanoscale imaging and characterization of lipid-based particles. However, obtaining images of such particles using AFM is still a challenge. The present study extends the capabilities of AFM to the characterization of proteoliposomes, a special class of liposomes composed of lipids and proteins, mimicking matrix vesicles (MVs) involved in the biomineralization process. To this end, proteoliposomes were synthesized, composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phospho-l-serine (DPPS), with inserted tissue-nonspecific alkaline phosphatase (TNAP) and/or annexin V (AnxA5), both characteristic proteins of osteoblast-derived MVs. We then aimed to study how TNAP and AnxA5 insertion affects the proteoliposomes' membrane properties and, in turn, interactions with type II collagen, thus mimicking early MV activity during biomineralization. AFM images of these proteoliposomes, acquired in dynamic mode, revealed the presence of surface protrusions with distinct viscoelasticity, thus suggesting that the presence of the proteins induced local changes in membrane fluidity. Surface protrusions were measurable in TNAP-proteoliposomes but barely detectable in AnxA5-proteoliposomes. More complex surface structures were observed for proteoliposomes harboring both TNAP and AnxA5 concomitantly, resulting in a lower affinity for type II collagen fibers compared to proteoliposomes harboring AnxA5 alone. The present study achieved the topographic analysis of lipid vesicles by direct visualization of structural changes, resulting from protein incorporation, without the need for fluorescent probes.

Serum Bioavailable Vitamin D Concentrations and Bone Mineral Density in Women After Obesity Surgery.

INTRODUCTION: Low bone mass after obesity surgery may arise as a consequence of chronic malabsorption of calcium and vitamin D. However, we have not found any role of serum 25-hydroxyvitamin D or of polymorphisms in the vitamin D receptor gene in previous studies. PURPOSE: To investigate the circulating bioavailable 25-hydroxyvitamin D in women after bariatric procedures and its association with bone mass. PATIENTS AND METHODS: The study consisted of 91 women on follow-up for 7 ± 2 years after bariatric surgery. We measured bone mineral density (BMD), serum parathormone (PTH), 25-hydroxyvitamin D, and vitamin D binding protein (VDBP). All patients were genotyped for two variants in the coding region of VDBP (rs4588 and rs7041). Bioavailable 25-hydroxyvitamin D was calculated in double homozygotes. RESULTS: We found a negative correlation between bioavailable 25-hydroxyvitamin D and PTH (r = -0.373, P = 0.018), but not with BMD at lumbar spine (r = -0.065, P = 0.682) or hip (r = -0.029, P = 0.857). When adjusting by age, similar results were found for PTH (r = -0.441, P = 0.005), BMD at lumbar spine (r = -0.026, P = 0.874) and hip (r = -0.096, P = 0.561). After multivariate linear regression, forcing bioavailable 25-hydroxyvitamin D into the model resulted in a weak significant association with BMD at the lumbar spine (ß = - 0.247, P = 0.025). CONCLUSIONS: Serum bioavailable 25-hydroxyvitamin D concentrations are not associated with bone mass loss after bariatric surgery in women. The negative association with serum PTH levels suggests that vitamin D supplementation partly improves secondary hyperparathyroidism, yet other mechanisms may contribute to low bone mass after bariatric surgery.

Acidosis is a key regulator of osteoblast ecto-nucleotidase pyrophosphatase/phosphodiesterase 1 (NPP1) expression and activity.

Previous work has shown that acidosis prevents bone nodule formation by osteoblasts in vitro by inhibiting mineralisation of the collagenous matrix. The ratio of phosphate (Pi ) to pyrophosphate (PPi ) in the bone microenvironment is a fundamental regulator of bone mineralisation. Both Pi and PPi , a potent inhibitor of mineralisation, are generated from extracellular nucleotides by the actions of ecto-nucleotidases. This study investigated the expression and activity of ecto-nucleotidases by osteoblasts under normal and acid conditions. We found that osteoblasts express mRNA for a number of ecto-nucleotidases including NTPdase 1-6 (ecto-nucleoside triphosphate diphosphohydrolase) and NPP1-3 (ecto-nucleotide pyrophosphatase/phosphodiesterase). The rank order of mRNA expression in differentiating rat osteoblasts (day 7) was Enpp1 > NTPdase 4 > NTPdase 6 > NTPdase 5 > alkaline phosphatase > ecto-5-nucleotidase > Enpp3 > NTPdase 1 > NTPdase 3 > Enpp2 > NTPdase 2. Acidosis (pH 6.9) upregulated NPP1 mRNA (2.8-fold) and protein expression at all stages of osteoblast differentiation compared to physiological pH (pH 7.4); expression of other ecto-nucleotidases was unaffected. Furthermore, total NPP activity was increased up to 53% in osteoblasts cultured in acid conditions (P < 0.001). Release of ATP, one of the key substrates for NPP1, from osteoblasts, was unaffected by acidosis. Further studies showed that mineralised bone formation by osteoblasts cultured from NPP1 knockout mice was increased compared with wildtypes (2.5-fold, P < 0.001) and was partially resistant to the inhibitory effect of acidosis. These results indicate that increased NPP1 expression and activity might contribute to the decreased mineralisation observed when osteoblasts are exposed to acid conditions.

Counter-regulatory phosphatases TNAP and NPP1 temporally regulate tooth root cementogenesis.

Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate (Pi) to mineral inhibitor pyrophosphate (PPi), where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase (TNAP) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1). The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enpp1 null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enpp1 gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected.

Hydrolysis of 2'3'-cGAMP by ENPP1 and design of nonhydrolyzable analogs.

Agonists of mouse STING (TMEM173) shrink and even cure solid tumors by activating innate immunity; human STING (hSTING) agonists are needed to test this therapeutic hypothesis in humans. The endogenous STING agonist is 2'3'-cGAMP, a second messenger that signals the presence of cytosolic double-stranded DNA. We report activity-guided partial purification and identification of ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP1) to be the dominant 2'3'-cGAMP hydrolyzing activity in cultured cells. The hydrolysis activity of ENPP1 was confirmed using recombinant protein and was depleted in tissue extracts and plasma from Enpp1(-/-) mice. We synthesized a hydrolysis-resistant bisphosphothioate analog of 2'3'-cGAMP (2'3'-cG(s)A(s)MP) that has similar affinity for hSTING in vitro and is ten times more potent at inducing IFN-ß secretion from human THP1 monocytes. Studies in mouse Enpp1(-/-) lung fibroblasts indicate that resistance to hydrolysis contributes substantially to its higher potency. 2'3'-cG(s)A(s)MP is therefore improved over natural 2'3'-cGAMP as a model agonist and has potential as a vaccine adjuvant and cancer therapeutic.

A novel approach to maintain gut mucosal integrity using an oral enzyme supplement.

OBJECTIVE: To determine the role of intestinal alkaline phosphatase (IAP) in enteral starvation-induced gut barrier dysfunction and to study its therapeutic effect as a supplement to prevent gut-derived sepsis. BACKGROUND: Critically ill patients are at increased risk for systemic sepsis and, in some cases, multiorgan failure leading to death. Years ago, the gut was identified as a major source for this systemic sepsis syndrome. Previously, we have shown that IAP detoxifies bacterial toxins, prevents endotoxemia, and preserves intestinal microbiotal homeostasis. METHODS: WT and IAP-KO mice were used to examine gut barrier function and tight junction protein levels during 48-hour starvation and fed states. Human ileal fluid samples were collected from 20 patients postileostomy and IAP levels were compared between fasted and fed states. To study the effect of IAP supplementation on starvation-induced gut barrier dysfunction, WT mice were fasted for 48 hours +/- IAP supplementation in the drinking water. RESULTS: The loss of IAP expression is associated with decreased expression of intestinal junctional proteins and impaired barrier function. For the first time, we demonstrate that IAP expression is also decreased in humans who are deprived of enteral feeding. Finally, our data demonstrate that IAP supplementation reverses the gut barrier dysfunction and tight junction protein losses due to a lack of enteral feeding. CONCLUSIONS: IAP is a major regulator of gut mucosal permeability and is able to ameliorate starvation-induced gut barrier dysfunction. Enteral IAP supplementation may represent a novel approach to maintain bowel integrity in critically ill patients.

Vascular calcification is dependent on plasma levels of pyrophosphate.

Plasma levels of pyrophosphate, an endogenous inhibitor of vascular calcification, are reduced in end-stage renal disease and correlate inversely with arterial calcification. However, it is not known whether the low plasma levels are directly pathogenic or are merely a marker of reduced tissue levels. This was tested in an animal model in which aortas were transplanted between normal mice and Enpp1(-/-) mice lacking ectonucleotide pyrophosphatase phosphodiesterase, the enzyme that synthesizes extracellular pyrophosphate. Enpp1(-/-) mice had very low plasma pyrophosphate and developed aortic calcification by 2 months that was greatly accelerated with a high-phosphate diet. Aortas of Enpp1(-/-) mice showed no further calcification after transplantation into wild-type mice fed a high-phosphate diet. Aorta allografts of wild-type mice calcified in Enpp1(-/-) mice but less so than the adjacent recipient Enpp1(-/-) aorta. Donor and recipient aortic calcium contents did not differ in transplants between wild-type and Enpp1(-/-) mice, demonstrating that transplantation per se did not affect calcification. Histology revealed medial calcification with no signs of rejection. Thus, normal levels of extracellular pyrophosphate are sufficient to prevent vascular calcification, and systemic Enpp1 deficiency is sufficient to produce vascular calcification despite normal vascular extracellular pyrophosphate production. This establishes an important role for circulating extracellular pyrophosphate in preventing vascular calcification.

Effects of polycystic ovary syndrome (PCOS), sex hormones, and obesity on circulating miRNA-21, miRNA-27b, miRNA-103, and miRNA-155 expression.

CONTEXT: MicroRNAs (miRNAs) are small, noncoding RNA sequences that negatively regulate gene expression at the post-transcriptional level. miRNA-21, miRNA-27b, miRNA-103, and miRNA-155 have been associated with metabolic disorders such as obesity and diabetes, which are also associated with polycystic ovary syndrome (PCOS). OBJECTIVE: We aimed to evaluate the effects of sex, sex hormones, and PCOS and their interactions with obesity on the expression in the circulation of these miRNAs. DESIGN: This was a case-control study. SETTINGS: The setting was an academic hospital. PARTICIPANTS: We included 12 control women, 12 patients with PCOS, and 12 men selected as to have similar body mass index (BMI) and age. Six subjects per group had normal weight (BMI < 25 kg/m(2)), and six subjects per group were obese (BMI ≥ 30 kg/m(2)). INTERVENTIONS: Blood samples were collected early in the morning after a 12-hour fast. MAIN OUTCOME MEASURES: We measured whole blood expression of miRNA-21, miRNA-27b, miRNA-103, and miRNA-155. RESULTS: Obesity significantly reduced the expression of miRNA-21, miRNA-27b, and miRNA-103. However, there was a significant interaction between obesity and the group of subjects in the expression of miRNA-21, miRNA-27b, miRNA-103, and miRNA-155 consisting of obesity reducing the expression of these miRNAs in control woman and men, but tending to increase their expression in women with PCOS. These differences paralleled those observed in serum T concentrations. CONCLUSIONS: The present results suggest that miRNAs that play an important role in metabolic and immune system processes are influenced by obesity and circulating androgen concentrations.

Extracellular matrix mineralization in periodontal tissues: Noncollagenous matrix proteins, enzymes, and relationship to hypophosphatasia and X-linked hypophosphatemia.

As broadly demonstrated for the formation of a functional skeleton, proper mineralization of periodontal alveolar bone and teeth - where calcium phosphate crystals are deposited and grow within an extracellular matrix - is essential for dental function. Mineralization defects in tooth dentin and cementum of the periodontium invariably lead to a weak (soft or brittle) dentition in which teeth become loose and prone to infection and are lost prematurely. Mineralization of the extremities of periodontal ligament fibers (Sharpey's fibers) where they insert into tooth cementum and alveolar bone is also essential for the function of the tooth-suspensory apparatus in occlusion and mastication. Molecular determinants of mineralization in these tissues include mineral ion concentrations (phosphate and calcium), pyrophosphate, small integrin-binding ligand N-linked glycoproteins and matrix vesicles. Amongst the enzymes important in regulating these mineralization determinants, two are discussed at length here, with clinical examples given, namely tissue-nonspecific alkaline phosphatase and phosphate-regulating gene with homologies to endopeptidases on the X chromosome. Inactivating mutations in these enzymes in humans and in mouse models lead to the soft bones and teeth characteristic of hypophosphatasia and X-linked hypophosphatemia, respectively, where the levels of local and systemic circulating mineralization determinants are perturbed. In X-linked hypophosphatemia, in addition to renal phosphate wasting causing low circulating phosphate levels, phosphorylated mineralization-regulating small integrin-binding ligand N-linked glycoproteins, such as matrix extracellular phosphoglycoprotein and osteopontin, and the phosphorylated peptides proteolytically released from them, such as the acidic serine- and aspartate-rich-motif peptide, may accumulate locally to impair mineralization in this disease.

Detección de la deleción F508 del gen CFTR por la técnica de mutagénesis dirigida mediante PCR en pacientes con enfermedad fibroquística / Detection of F508 Deletion in the CFTR Gene by PCR Directed Mutagenesis in Patients with fibrocystic Ddsease

La Fibrosis quística es la enfermedad autosómica recesiva más común en la población blanca y se caracteriza por la obstrucción de conductos, principalmente en pulmón, páncreas y tracto genital. Se presenta en uno de cada 2000 a 2500 nacidos vivos y tiene una frecuencia de portadores de uno cada 20 a 25 nacidos vivos. La enfermedad es causada por diferentes mutaciones en el gen regulador de la conductancia transmembrana de la fibrosis quística (CFTR). La mutación más frecuente en el gen CFTR es la deleción de tres pares de bases (CTT) denominada F508. Este trabajo se realizó con el fin de estandarizar la técnica de mutagénesis dirigida mediante PCR (PSM) para la detección de.la mutación F508 en pacientes con fibrosis quística. El método utilizado fue validado mediante secuenciación del DNA del exón 10 en todos los individuos. Mediante este análisis genético se detectaron seis individuos con las mutaciones F508 e I507. El método implementado en nuestro laboratorio podría servir para realizar un sondeo poblacional de portadores de mutaciones para la FQ.

Impact of the storage temperature on human plasma proteomic analysis: implications for the use of human plasma collections in research.

PURPOSE: To analyze the impact of storage temperature on the 2D-DIGE profile of human plasma. EXPERIMENTAL DESIGN: 2D-DIGE and MS were used to identify the differences in the proteomic profiles of aliquots of eight human plasma samples stored at either - 30 or - 80°C for 18 months. RESULTS: After the depletion of albumin and IgG, 2D-DIGE identified four spots significantly and reproducibly increased, and five spots that were decreased, in samples stored at - 30°C compared with those stored at - 80°C. These nine spots were manually excised, digested ingel and analyzed by MALDI-TOF/TOF. MASCOT database search using the PMF spectra allowed the identification of the proteins present in eight of the nine spots. All the spots corresponded to the complement C3 precursor protein. CONCLUSIONS AND CLINICAL RELEVANCE: Our present results indicate that plasma collections stored at -30°C, and not only those stored at - 80°C, may be used for 2D-DIGE analyses of albumin-and IgG-depleted human plasma without loosing the essential information about highly abundant proteins. This finding expands the applicability of 2D-DIGE to the study of human disease by permitting the analysis of human plasma samples stored at temperatures between - 30 and - 80°C.