Chiara Balducci

Cerebrospinal Fluid Lysosomal Enzymes and Alpha-Synuclein in Parkinson's Disease

To assess the discriminating power of multiple cerebrospinal fluid (CSF) biomarkers for Parkinsons disease (PD), we measured several proteins playing an important role in the disease pathogenesis. The activities of β‐glucocerebrosidase and other lysosomal enzymes, together with total and oligomeric α‐synuclein, and total and phosphorylated tau, were thus assessed in CSF of 71 PD patients and compared to 45 neurological controls. Activities of β‐glucocerebrosidase, β‐mannosidase, β‐hexosaminidase, and β‐galactosidase were measured with established enzymatic assays, while α‐synuclein and tau biomarkers were evaluated with immunoassays. A subset of PD patients (n = 44) was also screened for mutations in the β‐glucocerebrosidase‐encoding gene (GBA1). In the PD group, β‐glucocerebrosidase activity was reduced (P < 0.05) and patients at earlier stages showed lower enzymatic activity (P < 0.05); conversely, β‐hexosaminidase activity was significantly increased (P < 0.05). Eight PD patients (18%) presented GBA1 sequence variations; 3 of them were heterozygous for the N370S mutation. Levels of total α‐synuclein were significantly reduced (P < 0.05) in PD, in contrast to increased levels of α‐synuclein oligomers, with a higher oligomeric/total α‐synuclein ratio in PD patients when compared with controls (P < 0.001). A combination of β‐glucocerebrosidase activity, oligomeric/total α‐synuclein ratio, and age gave the best performance in discriminating PD from neurological controls (sensitivity 82%; specificity 71%, area under the receiver operating characteristic curve = 0.87). These results demonstrate the possibility of detecting lysosomal dysfunction in CSF and further support the need to combine different biomarkers for improving the diagnostic accuracy of PD.

Lysosomal hydrolases in cerebrospinal fluid from subjects with Parkinson's disease

Recent studies have shown a genetic association between glucocerebrosidase deficiencies and Parkinsons disease (PD). To further explore this issue the activity of β‐glucocerebrosidase and the activities of other lysosomal enzymes, α‐mannosidase, β‐mannosidase, β‐hexosaminidase, and β‐galactosidase have been evaluated in the cerebrospinal fluid (CSF) of PD patients. The activities of α‐mannosidase, β‐mannosidase, β‐glucocerebrosidase, and β‐hexosaminidase were substantially decreased in the CSF of PD patients, while levels of β‐galactosidase were essentially identical to controls. This study indicates that in PD several lysosomal hydrolases have decreased activities, further supporting a possible link between pathophysiological mechanisms underlying PD and lysosomal hydrolases.

Cerebrospinal fluid β-glucocerebrosidase activity is reduced in Dementia with Lewy Bodies

The autophagy-lysosomal degradation pathway plays a role in the onset and progression of neurodegenerative diseases. Clinical and genetic studies indicate that mutations of beta-glucocerebrosidase represent genetic risk factors for synucleinopathies, including Parkinsons Disease (PD) and Dementia with Lewy Bodies (DLB). We recently found a decreased activity of lysosomal hydrolases, namely beta-glucocerebrosidase, in cerebrospinal fluid of PD patients. We have thus measured the activity of these enzymes - alpha-mannosidase (EC 3.2.1.24), beta-mannosidase (EC 3.2.1.25), beta-glucocerebrosidase (EC 3.2.1.45), beta-galactosidase (EC 3.2.1.23) and beta-hexosaminidase (EC 3.2.1.52) - in cerebrospinal fluid of patients suffering from DLB, Alzheimers Disease (AD), Fronto-Temporal Dementia (FTD) and controls. Alpha-mannosidase activity showed a marked decrease across all the pathological groups as compared to controls. Conversely, beta-glucocerebrosidase activity was selectively reduced in DLB, further suggesting that this enzyme might specifically be impaired in synucleinopathies.

First pilot newborn screening for four lysosomal storage diseases in an Italian region: Identification and analysis of a putative causative mutation in the GBA gene

We report the first newborn screening pilot study in an Italian region for four lysosomal disorders including Pompe disease, Gaucher disease, Fabry disease and mucopolysaccharidosis type 1. The screening has been performed using enzymatic assay on Dry Blood Spot on filter paper. A total of 3403 newborns were screened. One newborn showed a reduction of β-glucosidase activity in leucocytes. Molecular analysis revealed a status of compound heterozygous for the panethnic mutation N370S and for the sequence variation E388K, not yet correlated to Gaucher disease onset. The functional consequences of the E388K replacement on β-glucosidase activity were evaluated by in vitro expression, showing that the mutant protein retained 48% of wild type activity. Structural modeling predicted that the E388K replacement, localized to a surface of the enzyme, would change the local charges distribution which, in the native protein, displays an overwhelming presence of negative charges. However, the newborn, and a 4 year old sister showing the same genomic alterations, are currently asymptomatic. This pilot newborn screening for lysosomal diseases appears to be feasible and affordable to be extended to large populations. Moreover other lysosomal diseases for which a therapy is available or will be available, could be included in the screening.

Basic fibroblast growth factor autocrine loop controls human osteosarcoma phenotyping and differentiation.

BackgroundWe focused on the phenotype of non-mineralizing MG63 and mineralizing TE85 human osteosarcoma cells and investigated the role of bFGF in modulating their differentiative responses. Basic FGF expression and bFGF effects on osteocalcin, runt-related transcription factor-2 (RUNX2), matrix molecular production and bFGF receptors, were evaluated.Materials and MethodsOsteocalcin and RUNX2 gene expression were studied by RT-PCR analysis. We evaluated cell proliferation by DNA content and performed differentiation studies on glycosaminoglican (GAG), collagen and proteoglican (PG) synthesis by using radiolabelled precursors and Northern blotting. BFGF receptors were quantified by bFGF receptor binding assay.ResultsOsteocalcin is expressed in MG63 and TE65. RUNX2 RNA is differentially spliced in the two cell lines. BFGF elicits the effects of differentially splicing RUNX2. Proliferation, GAG synthesis, bFGF and proteoglycan mRNA expression, high and low affinity bFGF receptors, were more marked in MG63 and differently affected by bFGF. Procollagen expression and alkaline phosphatase activity were significantly reduced. BFGF increased TE85 cell proliferation and reduced TE85 procollagen and osteocalcin production.ConclusionsThe different splice variants in RUNX2 gene in the two cell lines might be related to their different phenotypes. The less differentiated stage of MG63 could also be related to bFGF over-production and more bFGF receptors. The consequent increase in bFGF-bFGF receptor binding could explain the bFGF differentiative effects on MG63. We suggest an autocrine role of bFGF endogenous release in controlling the different osteosarcoma phenotypes.

Identification and molecular characterization of six novel mutations in the UDP-N-acetylglucosamine-1-phosphotransferase gamma subunit ( GNPTG) gene in patients with mucolipidosis III gamma

Mucolipidosis type III (MLIII) is an autosomal recessive disorder affecting lysosomal hydrolase trafficking. In a study of 10 patients from seven families with a clinical phenotype and enzymatic diagnosis of MLIII, six novel GNPTG gene mutations were identified. These included missense (p.T286M) and nonsense (p.W111X) mutations and a transition in the obligate AG‐dinucleotide of the intron 8 acceptor splice site (c.610–2A>G). Three microdeletions were also identified, two of which (c.611delG and c.640_667del28) were located within the coding region whereas one (c.609+28_610‐16del) was located entirely within intron 8. RT‐PCR analysis of the c.610–2A>G transition demonstrated that the change altered splicing, leading to the production of two distinct aberrantly spliced forms, viz. the skipping of exon 9 (p.G204_K247del) or the retention of introns 8 and 9 (p.G204VfsX28). RT‐PCR analysis, performed on a patient homozygous for the intronic deletion (c.609+28_610‐16del), failed to detect any GNPTG RNA transcripts. To determine whether c.609+28_610‐16del allele‐derived transcripts were subject to nonsense‐mediated mRNA decay (NMD), patient fibroblasts were incubated with the protein synthesis inhibitor anisomycin. An RT‐PCR fragment retaining 43 bp of intron 8 was consistently detected suggesting that the 33‐bp genomic deletion had elicited NMD. Quantitative real‐time PCR and GNPTG western blot analysis confirmed that the homozygous microdeletion p.G204VfsX17 had elicited NMD resulting in failure to synthesize GNPTG protein. Analysis of the sequences surrounding the microdeletion breakpoints revealed either intrinsic repetitivity of the deleted region or short direct repeats adjacent to the breakpoint junctions. This is consistent with these repeats having mediated the microdeletions via replication slippage and supports the view that the mutational spectrum of the GNPTG gene is strongly influenced by the properties of the local DNA sequence environment. Hum Mutat 30:1–7, 2009.

Synthesis and Secretion of Transforming Growth Factor-β1 by Human Desmoid Fibroblast Cell Line and Its Modulation by Toremifene

The present study provides evidence that the in vitro cultured fibroblast cell line from desmoid tumors differs from normal fibrobasts in its extracellular matrix (ECM) macromolecule composition and is modulated by treatment with toremifene, an antiestrogen that reduces tumor mass by an unknown mechanism. The results showed increased transforming growth factor-beta 1 (TGF-beta1) production, TGF-beta1 mRNA expression, and TGF-beta1 receptor number in desmoid fibroblasts compared with normal cells. As desmoid fibroblasts did not produce tumor necrosis factor-alpha (TNF-alpha) but were sensitive to it, which enhanced glycosaminoglycans (GAG) accumulation, we assessed the TGF-beta1 effects on TNF-alpha production by human monocytes. Our results showed TGF-beta1 significantly increased TNF-alpha secretion by monocytes. Toremifene mediated its effects in desmoid fibroblasts via an estrogen receptor-independent pathway. It inhibited GAG accumulation and the secretion of both latent and active forms of TGF-beta1 and had an inhibitory effect on TNF-alpha production by monocytes. Our results suggest that in reducing TGF-beta1 production by desmoid fibroblasts and TNF-alpha production by monocytes, toremifene may restore the balance between the two growth factors.

Effects of transforming growth factor-β1 and tumour necrosis factor-α on cultured fibroblasts from skin fibroma as modulated by toremifene

To determine how toremifene, an anti‐oestrogen triphenylethylene derivate, reduces tumour mass, we investigated its modulation of TGF‐β1 and TNF‐α in fibroma fibroblasts. Normal and fibroma fibroblasts, isolated from patients affected by Gardners syndrome without or with fibroma manifestation, were cultured in vitro. Secretion of GAG, collagen and TGF‐β1 was increased in fibroma fibroblasts compared to healthy cells. The increase in TGF‐β1 secretion into the medium was associated with a parallel increase in TGF‐β1 gene expression and receptor number. Receptor cross‐linking studies using radiolabelled TGF‐β1 revealed more receptors, particularly types I and II, in fibroma fibroblasts than in normal cells. Normal and fibroma fibroblasts did not synthesise TNF‐α, but they had TNF‐α membrane receptors, as shown by TNF‐α assay. TNF‐α secreted by human monocytes, which may be present in the peritumoral area, increased cell proliferation and GAG accumulation and was, in turn, enhanced by TGF‐β1 treatment. Both growth factors increased angiogenesis, as shown by the CAM assay. Toremifene reduced TGF‐β1 secretion by fibroma fibroblasts and TNF‐α secretion by monocytes, thus downregulating cell proliferation, ECM macromolecule accumulation and angiogenic progression. We hypothesise that increased TGF‐β1 gene expression and TGF‐β1 secretion in fibroma fibroblasts as well as the subsequent rise in TNF‐α production by monocytes may facilitate fibroma growth and that toremifene inhibits autocrine and paracrine growth factor production.

Identification of two novel β-mannosidosis-associated sequence variants: Biochemical analysis of β-mannosidase (MANBA) missense mutations

Beta-mannosidosis (OMIM # 248510) is an autosomal-recessive lysosomal storage disorder caused by deficiency of the lysosomal enzyme beta-mannosidase (MANBA, E.C. 3.2.1.25). The disorder has been reported in goat, cattle and man. The human disorder is rare and only 20 cases in 16 families have been reported. We have sequenced the exons and exon-intron borders in a European patient with infantile onset of beta-mannosidosis. The patient was compound heterozygous for a silent mutation (c.375A>G) in exon 3 causing alternative splicing, and a missense mutation (c.1513T>C, p.Ser505Pro) in exon 12. The alternative splicing event deleted four nucleotides from the transcript and was predicted to result in premature termination of translation. In order to evaluate the consequence of the missense mutation, we inserted the human beta-mannosidase gene into an expression vector, performed site-directed mutagenesis and expressed the normal and mutant enzyme in COS-7 cells. We also included the previously reported beta-mannosidosis-associated missense mutations c.544C>T (p.Arg182Trp) and c.1175G>A (p.Gly392Glu), which were found in patients presenting a milder phenotype. Cells transfected with the wild-type construct showed a 33-fold increase in beta-mannosidase activity compared to mock-transfected cells, whereas cells transfected with the mutant constructs showed no detectable increase in activity. We propose that the milder phenotype described in some beta-mannosidosis patients with missense mutations in the MANBA gene is not due to residual beta-mannosidase activity, but rather caused by epigenetic and/or environmental factors.

Human desmoid fibroblasts: matrix metalloproteinases, their inhibitors and modulation by Toremifene

BackgroundDesmoid tumour is a benign, non metastasising neoplasm characterised by an elevated deposition of organic macromolecules in the extracellular matrix (ECM). The matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases involved in the degradation of ECM macromolecules. The MMPs and their natural inhibitors (TIMPs) have been implicated in tumour growth, invasion and metastasis. In this study we provide evidence that the in vitro cultured cell line from desmoid tumour accumulates more collagen fibres in the ECM than healthy fibroblasts.MethodsWe investigated collagen accumulation by 3H-thymidine incorporation, MMP expression by substrate gel zymography and TIMP expression by Western blot analysis.ResultsDesmoid fibroblasts showed a reduction in MMP activity and an increase of type I and III collagen and TIMPs compared to normal fibroblasts.ConclusionThe increase in collagen in desmoid fibroblasts was due to inhibited collagen degradation (reduction of MMP activity) rather than to increased collagen synthesis. Adding toremifene, an anti-estrogen triphenylethylene derivate, to desmoid fibroblasts reduced collagen accumulation by decreasing mRNA expression and increasing collagen degradation.