New mutations and genotype-phenotype correlation in late-onset Pompe patients

Pompe disease is a glycogen storage disease caused by acid alfa-glucosidase deficiency. Here, we report clinical properties, genetic features of our late-onset Pompe patients. Seven patients were followed during the last 10 years in our institute. The clinical and laboratory findings were reviewed. Neuropsychological evaluation was performed in four patients. Myotonic discharges of paraspinal muscles and denervation potentials were seen in all patients at the diagnosis and were disappeared during follow-up in two. Only one patient, whose MRI showed cerebral atrophy, had attention and executive dysfunction. Compound heterozygous patients with IVS 1-13T>G have a milder disease. One patient who has homozygous IVS 1-13T>G mutation had more severe disease. Two of our patients who had very severe and fatal disease course carry double mutations on both alleles (c.547-39T>G and c.858+5ins7) that previously scored as "unknown" in Erasmus Pompe Center database. Lastly, we found new mutations (c.1209 C>A, 2737dupG) in two patients carrying IVS 1-13T>G in the other allele. Systemic involvements are very rare in late-onset Pompe patients. Similarly, Pompe disease does not cause cognitive impairment in adult population. Homozygous IVS 1-13T>G mutation and c.547-39T>G mutation which are previously noted as "unknown" pathogenicities cause a more severe disease.

Natural Prenylchalconaringenins and Prenylnaringenins as Antidiabetic Agents: α-Glucosidase and α-Amylase Inhibition and in Vivo Antihyperglycemic and Antihyperlipidemic Effects

Inhibition of α-glucosidase and α-amylase decreases postprandial blood glucose levels and delays glucose absorption, making it a treatment strategy for type 2 diabetes. This study examined in vivo and in vitro antidiabetic activities of natural prenylchalconaringenins 1 and 2 and prenylnaringenins 3 and 4, found in hops and beer. 3'-Geranylchalconaringenin (2) competitively and irreversibly inhibited α-glucosidase (IC₅₀ = 1.08 μM) with activity 50-fold higher than that of acarbose (IC₅₀ = 51.30 μM) and showed moderate inhibitory activity against α-amylase (IC₅₀ = 20.46 μM). Docking analysis substantiated these findings. In addition, compound 2 suppressed the increase in postprandial blood glucose levels and serum levels of total cholesterol and triglycerides in streptozotocin-induced diabetic mice. Taken together, these results suggest that 2 has dual inhibitory activity against α-glucosidase and α-amylase and alleviates diabetic hyperglycemia and hyperlipidemia, making it a potential functional food ingredient and drug candidate for management of type 2 diabetes.

Gut metagenomes of type 2 diabetic patients have characteristic single-nucleotide polymorphism distribution in Bacteroides coprocola

BACKGROUND

Gut microbes play a critical role in human health and disease, and researchers have begun to characterize their genomes, the so-called gut metagenome. Thus far, metagenomics studies have focused on genus- or species-level composition and microbial gene sets, while strain-level composition and single-nucleotide polymorphism (SNP) have been overlooked. The gut metagenomes of type 2 diabetes (T2D) patients have been found to be enriched with butyrate-producing bacteria and sulfate reduction functions. However, it is not known whether the gut metagenomes of T2D patients have characteristic strain patterns or SNP distributions.

FINDINGS

We downloaded public gut metagenome datasets from 170 T2D patients and 174 healthy controls and performed a systematic comparative analysis of their metagenome SNPs. We found that Bacteroides coprocola, whose relative abundance did not differ between the groups, had a characteristic distribution of SNPs in the T2D patient group. We identified 65 genes, all in B. coprocola, that had remarkably different enrichment of SNPs. The first and sixth ranked genes encode glycosyl hydrolases (GenBank accession EDU99824.1 and EDV02301.1). Interestingly, alpha-glucosidase, which is also a glycosyl hydrolase located in the intestine, is an important drug target of T2D. These results suggest that different strains of B. coprocola may have different roles in human gut and a specific set of B. coprocola strains are correlated with T2D.

Meadowsweet Teas as New Functional Beverages: Comparative Analysis of Nutrients, Phytochemicals and Biological Effects of Four Filipendula Species

In recent years, the increased popularity of functional beverages such as herbal teas and decoctions has led to the search for new sources of raw materials that provide appropriate taste and functionality to consumers. The objective of this study was to investigate the nutritional, phytochemical profiles and bioactivities of possible functional beverages produced from F. ulmaria and its alternative substitutes (F. camtschatica, F. denudata, F. stepposa). The investigated decoctions were analyzed regarding their macronutrient, carbohydrate, organic acid, amino acid and mineral composition. Quantification of the main phenolic compounds in the decoctions of meadowsweet floral teas was performed by a microcolumn RP-HPLC-UV procedure; the highest content was revealed in F. stepposa tea. The investigation of the essential oil of four meadowsweet teas revealed the presence of 28 compounds, including simple phenols, monoterpenes, sesquiterpenes and aliphatic components. The dominance of methyl salicylate and salicylaldehyde was noted in all samples. Studies on the water soluble polysaccharides of Filipendula flowers allowed us to establish their general affiliation to galactans and/or arabinogalactans with an admixture of glucans of the starch type and galacturonans as minor components. The bioactivity data demonstrated a good ability of meadowsweet teas to inhibit amylase, α-glucosidase and AGE formation. Tea samples showed antioxidant properties by the DPPH•, ABTS•+ and Br• free radicals scavenging assays and the carotene bleaching assay, caused by the presence of highly active ellagitannins. The anti-complement activity of the water-soluble polysaccharide fraction of meadowsweet teas indicated their possible immune-modulating properties. Filipendula beverage formulations can be expected to deliver beneficial effects due to their unique nutritional and phytochemical profiles. Potential applications as health-promoting functional products may be suggested.

Prospective exploratory muscle biopsy, imaging, and functional assessment in patients with late-onset Pompe disease treated with alglucosidase alfa: The EMBASSY Study

BACKGROUND

Late-onset Pompe disease is characterized by progressive skeletal myopathy followed by respiratory muscle weakness, typically leading to loss of ambulation and respiratory failure. In this population, enzyme replacement therapy (ERT) with alglucosidase alfa has been shown to stabilize respiratory function and improve mobility and muscle strength. Muscle pathology and glycogen clearance from skeletal muscle in treatment-naïve adults after ERT have not been extensively examined.

METHODS

This exploratory, open-label, multicenter study evaluated glycogen clearance in muscle tissue samples collected pre- and post- alglucosidase alfa treatment in treatment-naïve adults with late-onset Pompe disease. The primary endpoint was the quantitative reduction in percent tissue area occupied by glycogen in muscle biopsies from baseline to 6months. Secondary endpoints included qualitative histologic assessment of tissue glycogen distribution, secondary pathology changes, assessment of magnetic resonance images (MRIs) for intact muscle and fatty replacement, and functional assessments.

RESULTS

Sixteen patients completed the study. After 6months of ERT, the percent tissue area occupied by glycogen in quadriceps and deltoid muscles decreased in 10 and 8 patients, respectively. No changes were detected on MRI from baseline to 6months. A majority of patients showed improvements on functional assessments after 6months of treatment. All treatment-related adverse events were mild or moderate.

CONCLUSIONS

This exploratory study provides novel insights into the histopathologic effects of ERT in late-onset Pompe disease patients. Ultrastructural examination of muscle biopsies demonstrated reduced lysosomal glycogen after ERT. Findings are consistent with stabilization of disease by ERT in treatment-naïve patients with late-onset Pompe disease.

Determination of frequencies of alleles, associated with the pseudodeficiency of lysosomal hydrolases, in population of Ukraine

The pseudodeficiency of lysosomal hydrolases described as a significant reduction in enzyme activi­ty in vitro in clinically healthy individuals, can lead to diagnostic errors in the process of biochemical analysis of lysosomal storage disease in case of its combination with pathology of another origin. Pseudodeficiency is mostly caused by some non-pathogenic changes in the corresponding gene. These changes lead to the in vitro lability of the enzyme molecule, whereas in vivo the enzyme retains its functional activity. To assess the prevalence of the most common lysosomal hydrolases pseudodeficiency alleles in Ukraine, we have determined the frequency of alleles c.1055A>G and c.* 96A>G in the ARSA gene, substitutions c.739C>T (R247W) and c.745C>T (R249W) in the HEXA gene, c.1726G>A (G576S) and c.2065G>A (E689K) in the GAA gene, c.937G>T (D313Y) in the GLA1 gene and c.898G>A (A300T) in the IDUA gene in a group of 117 healthy individuals from different regions of the country and 14 heterozygous carriers of pathogenic mutations in the HEXA gene (parents of children with confirmed diagnosis of Tay-Sachs disease). The total frequency of haplotypes, associated with arylsulfatase A pseudodeficiency, in healthy people in Ukraine (c.1055G/c.*96G and c.1055G/c.*96A haplotypes) was 10.3%. The frequency of c.739C>T (R247W) allele, associated with hexo­saminidase A pseudodeficiency, among Tay-Sachs carriers from Ukraine was 7.1%. The total frequency of α-glucosidase pseudodeficiency haplotypes in healthy individuals in Ukraine (c.1726A/c.2065A and c.1726G/c.2065A haplotypes) was 2.6%. No person among examined individuals with the substitution c.937G>T (D313Y) in the GLA1 gene and c.898G>A (A300T) in the IDUA gene was found. The differential diagnostics of lysosomal storage diseases requires obligatory determination of the presence of the pseudodeficiency alleles, particularly the ones with high incidence in the total population. Ignoring phenomenon of pseudodeficiency may lead to serious diagnostic errors.

High-resolution Light Microscopy (HRLM) and Digital Analysis of Pompe Disease Pathology

Pompe disease is an autosomal recessive lysosomal storage disorder caused by a deficiency of the lysosomal enzyme acid α-glucosidase, responsible for the degradation of lysosomal glycogen. Absent or low levels of the enzyme leads to lysosomal glycogen accumulation in cardiac and skeletal muscle cells, resulting in progressive muscle weakness and death from cardiac or respiratory failure. Recombinant enzyme replacement and gene therapy are now being investigated as treatment modalities for this disease. A knockout mouse model for Pompe disease, induced by the disruption of exon 6 within the acid α-glucosidase gene, mimics the human disease and has been used to evaluate the efficacy of treatment modalities for clearing glycogen. However, for accurate histopathological assessment of glycogen clearance, maximal preservation of in situ lysosomal glycogen is essential. To improve retention of glycogen in Pompe tissues, several fixation and embedding regimens were evaluated. The best glycogen preservation was obtained when tissues fixed with 3% glutaraldehyde and postfixed with 1% osmium tetroxide were processed into epon-araldite. Preservation was confirmed by staining with the Periodic acid-Schiff's reaction and by electron microscopy. This methodology resulted in high-resolution light microscopy (HRLM) sections suitable for digital quantification of glycogen content in heart and skeletal muscle. Combining this method of tissue fixation with computer-assisted histomorphometry has provided us with what we believe is the most objective and reproducible means of evaluating histological glycogen load in Pompe disease.

Salmeterol enhances the cardiac response to gene therapy in Pompe disease

Enzyme replacement therapy (ERT) with recombinant human (rh) acid α-glucosidase (GAA) has prolonged the survival of patients. However, the paucity of cation-independent mannose-6-phosphate receptor (CI-MPR) in skeletal muscle, where it is needed to take up rhGAA, correlated with a poor response to ERT by muscle in Pompe disease. Clenbuterol, a selective β2 receptor agonist, enhanced the CI-MPR expression in striated muscle through Igf-1 mediated muscle hypertrophy, which correlated with increased CI-MPR (also the Igf-2 receptor) expression. In this study we have evaluated 4 new drugs in GAA knockout (KO) mice in combination with an adeno-associated virus (AAV) vector encoding human GAA, 3 alternative β2 agonists and dehydroepiandrosterone (DHEA). Mice were injected with AAV2/9-CBhGAA (1E+11 vector particles) at a dose that was not effective at clearing glycogen storage from the heart. Heart GAA activity was significantly increased by either salmeterol (p<0.01) or DHEA (p<0.05), in comparison with untreated mice. Furthermore, glycogen content was reduced in the heart by treatment with DHEA (p<0.001), salmeterol (p<0.05), formoterol (p<0.01), or clenbuterol (p<0.01) in combination with the AAV vector, in comparison with untreated GAA-KO mice. Wirehang testing revealed that salmeterol and the AAV vector significantly increased performance, in comparison with the AAV vector alone (p<0.001). Similarly, salmeterol with the vector increased performance significantly more than any of the other drugs. The most effective individual drugs had no significant effect in absence of vector, in comparison with untreated mice. Thus, salmeterol should be further developed as adjunctive therapy in combination with either ERT or gene therapy for Pompe disease.

Structural Analysis of Free N-Glycans in α-Glucosidase Mutants of Saccharomyces cerevisiae: Lack of the Evidence for the Occurrence of Catabolic α-Glucosidase Acting on the N-Glycans

Saccharomyces cerevisiae produces two different α-glucosidases, Glucosidase 1 (Gls1) and Glucosidase 2 (Gls2), which are responsible for the removal of the glucose molecules from N-glycans (Glc3Man9GlcNAc2) of glycoproteins in the endoplasmic reticulum. Whether any additional α-glucosidases playing a role in catabolizing the glucosylated N-glycans are produced by this yeast, however, remains unknown. We report herein on a search for additional α-glucosidases in S. cerevisiae. To this end, the precise structures of cytosolic free N-glycans (FNGs), mainly derived from the peptide:N-glycanase (Png1) mediated deglycosylation of N-glycoproteins were analyzed in the endoplasmic reticulum α-glucosidase-deficient mutants. 12 new glucosylated FNG structures were successfully identified through 2-dimentional HPLC analysis. On the other hand, non-glucosylated FNGs were not detected at all under any culture conditions. It can therefore be safely concluded that no catabolic α-glucosidases acting on N-glycans are produced by this yeast.

[Clinical characteristics and gene mutation analysis of one pedigree with infantile glycogen storage disease type II]

The clinical data of 2 infants with infantile glycogen storage disease type II (GSD II) from one pedigree were collected. The method of dried blood spots (DBS) was applied to collect peripheral blood samples, and the activity of acid alpha-D-glucosidase (GAA) in leukocytes was measured. The coding region of GAA gene in this pedigree was amplified by polymerase chain reaction and then direct sequencing was used to analyze mutations in GAA gene. The two infants were twins, who were admitted to the hospital due to feeding difficulties, generalized muscle weakness and hypotonia, cardiomegaly, and cardiac insufficiency when they were 10 months old. The GAA activity in leukocytes in the two infants was significantly lower than in normal controls. Gene sequencing revealed 2 compound heterozygous mutations in the two infants, i.e., G1942A and G2214A, respectively. G1942A had been proved pathogenic, and the latter one, G2214A, was a nonsense mutation, resulting in the change of tryptophan, the 738th amino acid of GAA, into a stop codon. The two infants were diagnosed with GSD II by gene detection and no enzyme replacement therapy could be provided to them. Follow-up visits showed that the two infants died at home at the age of 15 months and 17 months, respectively. GSD II is caused by deficiency of GAA activity resulting from mutation of GAA gene. The detection of GAA activity in peripheral blood by DBS and GAA gene detection are effective and feasible methods for diagnosis of GSD II.

Combined aerobic exercise and enzyme replacement therapy rejuvenates the mitochondrial-lysosomal axis and alleviates autophagic blockage in Pompe disease

A unifying feature in the pathogenesis of aging, neurodegenerative disease, and lysosomal storage disorders is the progressive deposition of macromolecular debris impervious to enzyme catalysis by cellular waste disposal mechanisms (e.g., lipofuscin). Aerobic exercise training (AET) has pleiotropic effects and stimulates mitochondrial biogenesis, antioxidant defense systems, and autophagic flux in multiple organs and tissues. Our aim was to explore the therapeutic potential of AET as an ancillary therapy to mitigate autophagic buildup and oxidative damage and rejuvenate the mitochondrial-lysosomal axis in Pompe disease (GSD II/PD). Fourteen weeks of combined recombinant acid α-glucosidase (rhGAA) and AET polytherapy attenuated mitochondrial swelling, fortified antioxidant defense systems, reduced oxidative damage, and augmented glycogen clearance and removal of autophagic debris/lipofuscin in fast-twitch skeletal muscle of GAA-KO mice. Ancillary AET potently augmented the pool of PI4KA transcripts and exerted a mild restorative effect on Syt VII and VAMP-5/myobrevin, collectively suggesting improved endosomal transport and Ca(2+)- mediated lysosomal exocytosis. Compared with traditional rhGAA monotherapy, AET and rhGAA polytherapy effectively mitigated buildup of protein carbonyls, autophagic debris/lipofuscin, and P62/SQSTM1, while enhancing MnSOD expression, nuclear translocation of Nrf-2, muscle mass, and motor function in GAA-KO mice. Combined AET and rhGAA therapy reactivates cellular clearance pathways, mitigates mitochondrial senescence, and strengthens antioxidant defense systems in GSD II/PD. Aerobic exercise training (or pharmacologic targeting of contractile-activity-induced pathways) may have therapeutic potential for mitochondrial-lysosomal axis rejuvenation in lysosomal storage disorders and related conditions (e.g., aging and neurodegenerative disease).

Late onset form of Pompe disease

BACKGROUND

Pompe disease is an autosomal recessive disorder of glycogen metabolism caused by deficiency in lysosomal enzyme α-glucosidase.

OBJECTIVES

We present first two patients from Slovakia with confirmed Pompe disease.

METHODS

Activity of α-glucosidase was measured using 4-methylumbelliferyl-α-D-glucopyranoside with the presence of acarbose, inhibitor that eliminates isoenzyme interference of maltase-glucoamylase. This methodical approach is substantial for determination of lysosomal enzyme deficiency. Using molecular genetic methods, PCR-RFLP and direct sequencing of coding region α-glucosidase gene (GAA) we have identified causal mutations in our patients.

RESULTS

Late-onset type of disease was confirmed by measuring α-glucosidase activity in leukocytes isolated from blood. The presence of common Caucasian mutation c.-32-13T>G was proved by genetic testing in the first patient in homozygous state. Second patient was a compound heterozygote, with mutation c.-32-13T>G on one allele and mutation A486P on the second allele.

CONCLUSION

We present a diagnostic algorithm for diagnosing the Pompe disease in patients of European origin. Enzyme replacement therapy has been used as a treatment option for improving the quality of life of patients. Early diagnosis and treatment of Pompe disease are considered to be critical for maximum efficacy of enzyme replacement therapy (Tab. 1, Fig. 3, Ref. 20).

Correcting Neuromuscular Deficits With Gene Therapy in Pompe Disease

OBJECTIVE

We have recently reported on the pathology of the neuromuscular junction (NMJ) in Pompe disease, reflecting disruption of neuronal and muscle homeostasis as a result of glycogen accumulation. The aim of this study was to examine how the alteration of NMJ physiology contributes to Pompe disease pathology; we performed molecular, physiological, and histochemical analyses of NMJ-related measures of the tibialis anterior muscles of young-, mid-, and late-stage alpha-glucosidase (GAA)-deficient mice.

METHODS

We performed intramuscular injection of an adeno-associated virus (AAV)9 vector expressing GAA (AAV9-hGAA) into the tibialis anterior muscle of Gaa(-/-) mice at early, mid, and severe pathological time points. We analyzed expression of NMJ-related genes, in situ muscle force production, and clearance of glycogen in conjunction with histological assessment of the NMJ.

RESULTS

Our data demonstrate that AAV9-hGAA is able to replace GAA to the affected tissue and modify AChR mRNA expression, muscle force production, motor endplate area, and innervation status. Importantly, the degree of restoration for these outcomes is limited by severity of disease. Early restoration of GAA activity was most effective, whereas late correction of GAA expression was not effective in modifying parameters reflecting NMJ structure and function nor in force restoration despite resolution of glycogen storage in muscle.

INTERPRETATION

Our data provide new mechanistic insight into the pathology of Pompe disease and suggest that early systemic correction to both neural and muscle tissues may be essential for successful correction of neuromuscular function in Pompe disease. Ann Neurol 2015;78:222-234.

[Analysis of clinical features of 6 patients with infantile type glycogen storage disease type II]

OBJECTIVE

To summarize clinical features and diagnosis of Chinese infantile patients with glycogen storage disease type II (GSD II).

METHOD

Six infant patients with GSD II diagnosed from January 2012 to June 2014 in the Department of Pediatrics, Peking University First Hospital were enrolled into this study. Clinical information of the 6 patients, including clinical manifestation, blood biochemistry, chest X-ray, echocardiogram, electrocardiogram, acid alpha-glucosidase (GAA) activity and GAA gene mutation analysis by direct sequencing of polymerase chain reaction (PCR) product were reviewed.

RESULT

Of the 6 patients, five were female and one was male, five of whom were classic infantile type while the other one was atypical. The age of onset ranged from birth to 3-month-old. All patients had varying degrees of generalized muscle weakness, hypotonia and development retardation or retrogression. Other common findings were feeding difficulties in two patients, tongue weakness in two patients, respiratory distress in four patients, macroglossia in one patient, and hepatomegaly in two patients. Left ventricular hypertrophy and cardiomegaly were obvious in all the six patients. All six patients were found to have a enlarged heart in physical examination, and three patients who underwent a chest X-ray examination had an enlarged heart shadow. Four patients who had an echocardiography were found to have myocardial hypertrophy. The electrocardiogram in three patients showed short PR intervals and high voltage. The creatine kinase (CK) levels were three to seven times elevated. The mildest elevated CK was 441 IU/L, and the highest CK level was 1 238 U/L. Assay of GAA enzyme activity in whole blood showed significantly reduced activity (1.3 nmol/ (spot·d) to 2 nmol/(spot·d)) in the patients tested. Gene sequencing in 4 patients showed 8 pathogenic mutations, including 6 missense mutations, one nonsense mutation and one frameshift mutation. The missense mutations were c.998C > A (p.Thr333Lys), c.1280T > C (p.Met427Thr), c.1760T > C (p.Leu587Pro), c.1924G > T (p.Val642Phe), c.2012T > A (p.Met671Lys) and c.2105G > A (p.Arg702His). The nonsense mutation was c2662G > T (p.Glu888X), and the frameshift mutation was c2812_2813delTG (p.Cys938fs). The 5 classic infantile patients died at the age of 7 to 22 months. The atypical infantile patient was 2 years and five months old according to our latest follow up.

CONCLUSION

Infantile GSD II had similar motor manifestations and cardiac involvements, blood biochemical test, imaging findings, enzyme assays, though there were slight differences. The probability of GSD II should be taken into consideration if an infant has both muscular disease and cardiac involvement.

A study of up to 12 years of follow-up of Friedreich ataxia utilising four measurement tools

OBJECTIVE

To explore the progression of Friedreich ataxia by analysing the change in scores of four clinical measures (the Friedreich Ataxia Rating Scale (FARS), the International Cooperative Ataxia Rating Scale (ICARS), the Functional Independence Measure (FIM) and the Modified Barthel Index (MBI)) over a period of up to 12 years, to ascertain the effects of clinical variables on performance of these measures, and to determine the most sensitive rating scale for measuring disease progression.

METHODS

We measured the disease progression of up to 147 individuals against disease duration grouped into 5-year intervals. Additional subgroups were created to study the effects of the size of the smaller FXN intron 1 GAA repeat size (GAA1) and onset age on rating scale performance.

RESULTS

Both the FARS and ICARS demonstrated greater change in the first 20 years post disease onset than in the subsequent 20 years during which there was little change in the mean score. While the FIM and MBI continued to deteriorate beyond 20 years post disease onset, floor effects were noted. As measured by the FARS, individuals with a larger GAA1 repeat were found to progress more quickly in the first 20 years of disease.

CONCLUSIONS

Individuals with larger GAA1 repeat sizes and earlier ages of disease onset were shown to deteriorate at a faster rate and were associated with greater FARS and ICARS scores and lower FIM and MBI scores, which are indicative of greater disease severity.

Effects of MAL61 and MAL62 overexpression on maltose fermentation of baker's yeast in lean dough

The predominant fermentable sugar in lean dough is maltose. To improve the leavening ability of baker's yeast in lean dough, maltose metabolism should be improved. Maltase (alpha-glucosidase, encoded by MAL62) and maltose permease (encoded by MAL61) are the major factors involved in maltose metabolism. The major rate-limiting factor in maltose metabolism and leavening ability of baker's yeast remains unclear. In this work, MAL61 and/or MAL62 overexpression strains were constructed to investigate the decisive factor for maltose metabolism of industrial baker's yeast in lean dough. Our results show that elevated maltose permease activity by MAL61 overexpression yielded less improvement in maltose fermentation compared to elevated maltase activity by MAL62 overexpression. Significant increase in maltase activity by MAL62 overexpression could result in a 44% increase in leavening ability of industrial baker's yeast in lean dough and a 39% increase in maltose metabolism in a medium containing glucose and maltose. Thus, maltase was the rate-limiting factor in maltose fermentation of industrial baker's yeast in lean dough. This study lays a foundation for breeding of industrial baker's yeast for quick dough leavening.

A new ester of fatty acid from a methanol extract of the whole plant of Amaranthus spinosus and its α-glucosidase inhibitory activity

CONTEXT

Amaranthus spinosus Linn. (Amaranthaceae), commonly known as "spiny pigweed", is used both in the Indian traditional system and in folk medicine to treat diabetes.

OBJECTIVE

The present study evaluates the scientific basis of antidiabetic activity of chloroform fraction of methanol extract of A. spinosus and of an isolated constituent of A. spinosus.

MATERIALS AND METHODS

HPLC analysis was performed to determine the purity and the amount of the constituent present in the plant extract. The yeast α-glucosidase inhibition technique was used to determine the antidiabetic activity of A. spinosus. Acarbose was used as a standard. An appropriate therapeutic approach for preventing diabetes mellitus and obesity is to retard the absorption of glucose by inhibition of α-glucosidase.

RESULTS

One novel fatty acid with strong α-glucosidase inhibitory activity - (14E, 18E, 22E, 26E) - methyl nonacosa-14, 18, 22, 26 tetraenoate [1] (IC50 value 6.52 µM/mL) and β-sitosterol [2] were purified. Compound 1 was found to be more potent than the methanol extract. HPLC quantitative analysis revealed that 0.15% of compound 1 and 0.06% of compound 2 were present in the plant extract.

CONCLUSION

This novel fatty acid can potentially be developed as a novel natural nutraceutical for the management of diabetes.

Enzyme therapy and immune response in relation to CRIM status: the Dutch experience in classic infantile Pompe disease

BACKGROUND

Enzyme-replacement therapy (ERT) in Pompe disease--an inherited metabolic disorder caused by acid α-glucosidase deficiency and characterized in infants by generalized muscle weakness and cardiomyopathy--can be complicated by immune responses. Infants that do not produce any endogenous acid α-glucosidase, so-called CRIM-negative patients, reportedly develop a strong response. We report the clinical outcome of our Dutch infants in relation to their CRIM status and immune response.

METHODS

Eleven patients were genotyped and their CRIM status was determined. Antibody formation and clinical outcome were assessed for a minimum of 4 years.

RESULTS

ERT was commenced between 0.1 and 8.3 months of age, and patients were treated from 0.3 to 13.7 years. All patients developed antibodies. Those with a high antibody titer (above 1:31,250) had a poor response. The antibody titers varied substantially between patients and did not strictly correlate with the patients' CRIM status. Patients who started ERT beyond 2 months of age tended to develop higher titers than those who started earlier. All three CRIM-negative patients in our study succumbed by the age of 4 years seemingly unrelated to the height of their antibody titer.

CONCLUSION

Antibody formation is a common response to ERT in classic infantile Pompe disease and counteracts the effect of treatment. The counteracting effect seems determined by the antibody:enzyme molecular stoichiometry. The immune response may be minimized by early start of ERT and by immune modulation, as proposed by colleagues. The CRIM-negative status itself seems associated with poor outcome.

Two novel mutations in acid α-glucosidase gene in two patients with Pompe disease

Pompe disease is an autosomal recessive lysosomal glycogen storage disorder (GSD) caused by acid α-glucosidase (GAA) deficiency. Pompe disease has a broad genotypic and phenotypic spectrum. The infantile-onset form is the most severe form and presents with hypotonia and cardiomyopathy in early infancy. The probands who died were found to have GSD type II based on clinical and biochemical findings. We report two families with Pompe disease in whom the parents' molecular analysis revealed two novel mutations: c.2045A>G (p.Q682R) and c.763C>T (p.Q255X).

Duplication of a promiscuous transcription factor drives the emergence of a new regulatory network

The emergence of new genes throughout evolution requires rewiring and extension of regulatory networks. However, the molecular details of how the transcriptional regulation of new gene copies evolves remain largely unexplored. Here we show how duplication of a transcription factor gene allowed the emergence of two independent regulatory circuits. Interestingly, the ancestral transcription factor was promiscuous and could bind different motifs in its target promoters. After duplication, one paralogue evolved increased binding specificity so that it only binds one type of motif, whereas the other copy evolved a decreased activity so that it only activates promoters that contain multiple binding sites. Interestingly, only a few mutations in both the DNA-binding domains and in the promoter binding sites were required to gradually disentangle the two networks. These results reveal how duplication of a promiscuous transcription factor followed by concerted cis and trans mutations allows expansion of a regulatory network.

Molecular Cloning of cDNAs and Genes for Three α-Glucosidases from European Honeybees,Apis melliferaL., and Heterologous Production of Recombinant Enzymes inPichia pastoris

cDNAs encoding three alpha-glucosidases (HBGases I, II, and III) from European honeybees, Apis mellifera, were cloned and sequenced, two of which were expressed in Pichia pastoris. The cDNAs for HBGases I, II, and III were 1,986, 1,910, and 1,915 bp in length, and included ORFs of 1,767, 1,743, and 1,704 bp encoding polypeptides comprised of 588, 580, and 567 amino acid residues, respectively. The deduced proteins of HBGases I, II, and III contained 18, 14, and 8 putative N-linked glycosylation sites, respectively, but at least 2 sites in HBGase II were unmodified by N-linked oligosaccharide. In spite of remarkable differences in the substrate specificities of the three HBGases, high homologies (38-44% identity) were found in the deduced amino acid sequences. In addition, three genomic DNAs, of 13,325, 2,759, and 27,643 bp, encoding HBGases I, II, and III, respectively, were isolated from honeybees, and the sequences were analyzed. The gene of HBGase I was found to be composed of 8 exons and 7 introns. The gene of HBGase II was not divided by intron. The gene of HBGase III was confirmed to be made up of 9 exons and 8 introns, and to be located in the region upstream the gene of HBGase I.

OsMOGS is required for N-glycan formation and auxin-mediated root development in rice (Oryza sativa L.)

N-glycosylation is a major modification of glycoproteins in eukaryotic cells. In Arabidopsis, great progress has been made in functional analysis of N-glycan production, however there are few studies in monocotyledons. Here, we characterized a rice (Oryza sativa L.) osmogs mutant with shortened roots and isolated a gene that coded a putative mannosyl-oligosaccharide glucosidase (OsMOGS), an ortholog of α-glucosidase I in Arabidopsis, which trims the terminal glucosyl residue of the oligosaccharide chain of nascent peptides in the endoplasmic reticulum (ER). OsMOGS is strongly expressed in rapidly cell-dividing tissues and OsMOGS protein is localized in the ER. Mutation of OsMOGS entirely blocked N-glycan maturation and inhibited high-mannose N-glycan formation. The osmogs mutant exhibited severe defects in root cell division and elongation, resulting in a short-root phenotype. In addition, osmogs plants had impaired root hair formation and elongation, and reduced root epidemic cell wall thickness due to decreased cellulose synthesis. Further analysis showed that auxin content and polar transport in osmogs roots were reduced due to incomplete N-glycosylation of the B subfamily of ATP-binding cassette transporter proteins (ABCBs). Our results demonstrate that involvement of OsMOGS in N-glycan formation is required for auxin-mediated root development in rice.