Stefano Squarzoni

Publications (37)121.54 Total impact

• Article: ANTISENSE-INDUCED MESSENGER DEPLETION CORRECTS A COL6A2 DOMINANT MUTATION IN ULLRICH MYOPATHY.

  Francesca Gualandi, Elisa Manzati, Patrizia Sabatelli, Chiara Passarelli, Matteo Bovolenta, Camilla Pellegrini, Daniela Perrone, Stefano Squarzoni, Elena Pegoraro, Paolo Bonaldo, Alessandra Ferlini
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  ABSTRACT: Collagen VI genes mutations cause Ullrich and Bethlem muscular dystrophies. Pathogenic mutations frequently have a dominant negative effect, with defect in collagen VI chains secretion and assembling. It is agreed that, conversely, collagen VI haploinsufficiency has no pathological consequences. Thus, RNA targeting approaches aimed at preferentially inactivating the mutated COL6 messenger may represent a promising therapeutic strategy. By in vitro studies we obtained the preferential depletion of the mutated COL6A2 messenger, by targeting a common SNPs, cistronic with a dominant COL6A2 mutation. We used a 2'OMePS antisense oligonucleotide covering the SNP within exon 3, which is out of frame. Exon 3 skipping has the effect of depleting the mutated transcript via RNA nonsense-mediated decay, recovering the correct collagen VI secretion and restoring the ability to form an interconnected microfilament network into the extracellular matrix. This novel RNA modulation approach to correcting dominant mutations may represent a therapeutic strategy potentially applicable to a great variety of mutations and diseases.
  Human gene therapy 09/2012; · 4.20 Impact Factor
• Article: Familial partial lipodystrophy, mandibuloacral dysplasia and restrictive dermopathy feature barrier-to-autointegration factor (BAF) nuclear redistribution.

  Cristina Capanni, Stefano Squarzoni, Vittoria Cenni, Maria Rosaria D'Apice, Alessandra Gambineri, Giuseppe Novelli, Manfred Wehnert, Renato Pasquali, Nadir M Maraldi, Giovanna Lattanzi
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  ABSTRACT: Prelamin A processing impairment is a common feature of a restricted group of rare genetic alterations/disorders associated with a wide range of clinical phenotypes. Changes in histone posttranslational modifications, alterations in non-histone chromatin proteins and chromatin disorganization have been specifically linked to impairment of specific, distinct prelamin A processing steps, but the molecular mechanism involved in these processes is not yet understood . In this study, we show that the accumulation of wild-type prelamin A detected in restrictive dermopathy (RD), as well as the accumulation of mutated forms of prelamin A identified in familial partial lipodystrophy (FPLD) and mandibuloacral dysplasia (MADA), affect the nuclear localization of barrier-to-autointegration factor (BAF), a protein able to link lamin A precursor to chromatin remodeling functions. Our findings, in accordance with previously described results, support the hypothesis of a prelamin A involvement in BAF nuclear recruitment and suggest BAF-prelamin A complex as a protein platform usually activated in prelamin A-accumulating diseases. Finally, we demonstrate the involvement of the inner nuclear membrane protein emerin in the proper localization of BAF-prelamin A complex.
  Cell cycle (Georgetown, Tex.) 08/2012; 11(19):3568-77. · 5.36 Impact Factor
• Article: Altered chromatin organization and SUN2 localization in mandibuloacral dysplasia are rescued by drug treatment.

  Daria Camozzi, Maria Rosaria D'Apice, Elisa Schena, Vittoria Cenni, Marta Columbaro, Cristina Capanni, Nadir M Maraldi, Stefano Squarzoni, Michela Ortolani, Giuseppe Novelli, Giovanna Lattanzi
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  ABSTRACT: Mandibuloacral dysplasia type A (MADA) is a rare laminopathy characterized by growth retardation, craniofacial anomalies, bone resorption at specific sites including clavicles, phalanges and mandibula, mottled cutaneous pigmentation, skin rigidity, partial lipodystrophy, and insulin resistance. The disorder is caused by recessive mutations of the LMNA gene encoding for A-type lamins. The molecular feature of MADA consists in the accumulation of the unprocessed lamin A precursor, which is detected at the nuclear rim and in intranuclear aggregates. Here, we report the characterization of prelamin A post-translational modifications in MADA cells that induce alterations in the chromatin arrangement and dislocation of nuclear envelope-associated proteins involved in correct nucleo-cytoskeleton relationships. We show that protein post-translational modifications change depending on the passage number, suggesting the onset of a feedback mechanism. Moreover, we show that treatment of MADA cells with the farnesyltransferase inhibitors is effective in the recovery of the chromatin phenotype, altered in MADA, provided that the cells are at low passage number, while at high passage number, the treatment results ineffective. Moreover, the distribution of the lamin A interaction partner SUN2, a constituent of the nuclear envelope, is altered by MADA mutations, as argued by the formation of a highly disorganized lattice. Treatment with statins partially rescues proper SUN2 organization, indicating that its alteration is caused by farnesylated prelamin A accumulation. Given the major role of SUN1 and SUN2 in the nucleo-cytoskeleton interactions and in regulation of nuclear positioning in differentiating cells, we hypothesise that mechanisms regulating nuclear membrane-centrosome interplay and nuclear movement may be affected in MADA fibroblasts.
  Histochemie 06/2012; 138(4):643-51. · 2.59 Impact Factor
• Source

  Available from: Sudheer Kumar Gara

  Article: Expression of collagen VI α5 and α6 chains in human muscle and in Duchenne muscular dystrophy-related muscle fibrosis.

  Patrizia Sabatelli, Francesca Gualandi, Sudheer Kumar Gara, Paolo Grumati, Alessandra Zamparelli, Elena Martoni, Camilla Pellegrini, Luciano Merlini, Alessandra Ferlini, Paolo Bonaldo, Nadir Mario Maraldi, Mats Paulsson, Stefano Squarzoni, Raimund Wagener
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  ABSTRACT: Collagen VI is a major extracellular matrix (ECM) protein with a critical role in maintaining skeletal muscle functional integrity. Mutations in COL6A1, COL6A2 and COL6A3 genes cause Ullrich Congenital Muscular Dystrophy (UCMD), Bethlem Myopathy, and Myosclerosis. Moreover, Col6a1(-/-) mice and collagen VI deficient zebrafish display a myopathic phenotype. Recently, two additional collagen VI chains were identified in humans, the α5 and α6 chains, however their distribution patterns and functions in human skeletal muscle have not been thoroughly investigated yet. By means of immunofluorescence analysis, the α6 chain was detected in the endomysium and perimysium, while the α5 chain labeling was restricted to the myotendinous junctions. In normal muscle cultures, the α6 chain was present in traces in the ECM, while the α5 chain was not detected. In the absence of ascorbic acid, the α6 chain was mainly accumulated into the cytoplasm of a sub-set of desmin negative cells, likely of interstitial origin, which can be considered myofibroblasts as they expressed α-smooth muscle actin. TGF-β1 treatment, a pro-fibrotic factor which induces trans-differentiation of fibroblasts into myofibroblasts, increased the α6 chain deposition in the extracellular matrix after addition of ascorbic acid. In order to define the involvement of the α6 chain in muscle fibrosis we studied biopsies of patients affected by Duchenne Muscular Dystrophy (DMD). We found that the α6 chain was dramatically up-regulated in fibrotic areas where, in contrast, the α5 chain was undetectable. Our results show a restricted and differential distribution of the novel α6 and α5 chains in skeletal muscle when compared to the widely distributed, homologous α3 chain, suggesting that these new chains may play specific roles in specialized ECM structures. While the α5 chain may have a specialized function in tissue areas subjected to tensile stress, the α6 chain appears implicated in ECM remodeling during muscle fibrosis.
  Matrix biology: journal of the International Society for Matrix Biology 04/2012; 31(3):187-96. · 3.56 Impact Factor
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  Available from: Sudheer Kumar Gara

  Article: Differential and restricted expression of novel collagen VI chains in mouse.

  Sudheer Kumar Gara, Paolo Grumati, Stefano Squarzoni, Patrizia Sabatelli, Anna Urciuolo, Paolo Bonaldo, Mats Paulsson, Raimund Wagener
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  ABSTRACT: Recently, three novel collagen VI chains, α4, α5 and α6, were identified. These are thought to substitute for the collagen VI α3 chain, probably forming α1α2α4, α1α2α5 or α1α2α6 heterotrimers. The expression pattern of the novel chains is so far largely unknown. In the present study, we compared the tissue distribution of the novel collagen VI chains in mouse with that of the α3 chain by immunohistochemistry, immunoelectron microscopy and immunoblots. In contrast to the widely expressed α3 chain, the novel chains show a highly differential, restricted and often complementary expression. The α4 chain is strongly expressed in the intestinal smooth muscle, surrounding the follicles in ovary, and in testis. The α5 chain is present in perimysium and at the neuromuscular junctions in skeletal muscle, in skin, in the kidney glomerulus, in the interfollicular stroma in ovary and in the tunica albuginea of testis. The α6 chain is most abundant in the endomysium and perimysium of skeletal muscle and in myocard. Immunoelectron microscopy of skeletal muscle localized the α6 chain to the reticular lamina of muscle fibers. The highly differential and restricted expression points to the possibility of tissue-specific roles of the novel chains in collagen VI assembly and function.
  Matrix biology: journal of the International Society for Matrix Biology 05/2011; 30(4):248-57. · 3.56 Impact Factor
• Article: Prelamin A processing and functional effects in restrictive dermopathy.

  Marta Columbaro, Elisabetta Mattioli, Elisa Schena, Cristina Capanni, Vittoria Cenni, Nicolas Levy, Claire L Navarro, Rosalba Del Coco, Stefano Squarzoni, Daria Camozzi, Chris J Hutchison, Manfred Wehnert, Giovanna Lattanzi
  Cell cycle (Georgetown, Tex.) 12/2010; 9(23):4766-8. · 5.36 Impact Factor
• Article: Muscular laminopathies: role of prelamin A in early steps of muscle differentiation.

  Nadir M Maraldi, Cristina Capanni, Rosalba Del Coco, Stefano Squarzoni, Marta Columbaro, Elisabetta Mattioli, Giovanna Lattanzi, Francesco A Manzoli
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  ABSTRACT: Lamin A is a nuclear envelope constituent involved in a group of human disorders, collectively referred to as laminopathies, which include Emery-Dreifuss muscular dystrophy. Because increasing evidence suggests a role of lamin A precursor in nuclear functions, we investigated the processing of prelamin A along muscle differentiation. Both protein levels and cellular localization of prelamin A appears to be modulated during C2C12 mouse myoblasts activation. Similar changes also occur in the expression of two lamin A-binding proteins: emerin and LAP2α. Furthermore prelamin A forms a complex with LAP2α in differentiating myoblasts. Prelamin A accumulation in cycling myoblasts by expressing unprocessable mutants affects LAP2α and PCNA amount and increases caveolin 3 mRNA and protein levels, whilst accumulation of prelamin A in differentiated muscle cells following treatment with a farnesyl transferase inhibitor inhibits caveolin 3 expression. These data provide evidence for a critical role of lamin A precursor in the early steps of muscle cell differentiation. In fact the post-translational processing of prelamin A affects caveolin 3 expression and influences the myoblast differentiation process. Thus, altered lamin A processing could affect myoblast differentiation and/or muscle regeneration and might contribute to the myopathic phenotype.
  Advances in enzyme regulation 10/2010; 51(1):246-56.
• Source

  Available from: Rosa Curci

  Article: Expression of the Collagen VI α5 and α6 Chains in Normal Human Skin and in Skin of Patients with Collagen VI-Related Myopathies

  Patrizia Sabatelli, Sudheer K Gara, Paolo Grumati, Anna Urciuolo, Francesca Gualandi, Rosa Curci, Stefano Squarzoni, Alessandra Zamparelli, Elena Martoni, Luciano Merlini, Mats Paulsson, Paolo Bonaldo, Raimund Wagener
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  ABSTRACT: Collagen VI is an extracellular matrix protein with critical roles in maintaining muscle and skin integrity and function. Skin abnormalities, including predisposition to keratosis pilaris and abnormal scarring, were described in Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy (BM) patients carrying mutations in COL6A1, COL6A2, and COL6A3 genes, whereas COL6A5, previously designated as COL29A1, was linked to atopic dermatitis. To gain insight into the function of the newly identified collagen VI α5 and α6 chains in human skin, we studied their expression and localization in normal subjects and in genetically characterized UCMD and BM patients. We found that localization of α5, and to a lesser extent α6, is restricted to the papillary dermis, where the protein mainly colocalizes with collagen fibrils. In addition, both chains were found around blood vessels. In UCMD patients with COL6A1 or COL6A2 mutations, immunolabeling for α5 and α6 was often altered, whereas in a UCMD and in a BM patient, each with a COL6A3 mutation, expression of α5 and α6 was apparently unaffected, suggesting that these chains may substitute for α3, forming α1α2α5 or α1α2α6 heterotrimers.Abbreviations: BM, Bethlem myopathy; UMCD, Ullrich congential muscular dystrophy
  Journal of Investigative Dermatology 09/2010; 131(1):99-107. · 6.31 Impact Factor
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  Available from: orphanresearch.net

  Article: Lamin A precursor induces barrier-to-autointegration factor nuclear localization.

  Cristina Capanni, Vittoria Cenni, Tokuko Haraguchi, Stefano Squarzoni, Stefan Schüchner, Egon Ogris, Giuseppe Novelli, Nadir Maraldi, Giovanna Lattanzi
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  ABSTRACT: Lamin A, a protein component of the nuclear lamina, is synthesized as a precursor named prelamin A, whose multi-step maturation process involves different protein intermediates. As demonstrated in laminopathies such as familial partial lipodystrophy, mandibuloacral dysplasia, Werner syndrome, Hutchinson-Gilford progeria syndrome and restrictive dermopathy, failure of prelamin A processing results in the accumulation of lamin A protein precursors inside the nucleus which dominantly produces aberrant chromatin structure. To understand if nuclear lamina components may be involved in prelamin A chromatin remodeling effects, we investigated barrier-to-autointegration factor (BAF) localization and expression in prelamin A accumulating cells. BAF is a DNA-binding protein that interacts directly with histones, lamins and LEM-domain proteins and has roles in chromatin structure, mitosis and gene regulation. In this study, we show that the BAF heterogeneous localization between nucleus and cytoplasm observed in HEK293 cycling cells changes in response to prelamin A accumulation. In particular, we observed that the accumulation of lamin A, non-farnesylated prelamin A and farnesylated carboxymethylated lamin A precursors induce BAF nuclear translocation. Moreover, we show that the treatment of human fibroblasts with prelamin A interfering drugs results in similar changes. Finally, we report that the accumulation of progerin, a truncated form of farnesylated and carboxymethylated prelamin A identified in Hutchinson-Gilford progeria syndrome cells, induces BAF recruitment in the nucleus. These findings are supported by coimmunoprecipitation of prelamin A or progerin with BAF in vivo and suggest that BAF could mediate prelamin A-induced chromatin effects.
  Cell cycle (Georgetown, Tex.) 07/2010; 9(13):2600-10. · 5.36 Impact Factor
• Article: Recessive COL6A2 C-globular missense mutations in Ullrich congenital muscular dystrophy: role of the C2a splice variant.

  Rui-Zhu Zhang, Yaqun Zou, Te-Cheng Pan, Dessislava Markova, Andrzej Fertala, Ying Hu, Stefano Squarzoni, Umbertina Conti Reed, Suely K N Marie, Carsten G Bönnemann, Mon-Li Chu
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  ABSTRACT: Ullrich congenital muscular dystrophy (UCMD) is a disabling and life-threatening disorder resulting from either recessive or dominant mutations in genes encoding collagen VI. Although the majority of the recessive UCMD cases have frameshift or nonsense mutations in COL6A1, COL6A2, or COL6A3, recessive structural mutations in the COL6A2 C-globular region are emerging also. However, the underlying molecular mechanisms have remained elusive. Here we identified a homozygous COL6A2 E624K mutation (C1 subdomain) and a homozygous COL6A2 R876S mutation (C2 subdomain) in two UCMD patients. The consequences of the mutations were investigated using fibroblasts from patients and cells stably transfected with the mutant constructs. In contrast to expectations based on the clinical severity of these two patients, secretion and assembly of collagen VI were moderately affected by the E624K mutation but severely impaired by the R876S substitution. The E624K substitution altered the electrostatic potential of the region surrounding the metal ion-dependent adhesion site, resulting in a collagen VI network containing thick fibrils and spots with densely packed microfibrils. The R876S mutation prevented the chain from assembling into triple-helical collagen VI molecules. The minute amount of collagen VI secreted by the R876S fibroblasts was solely composed of a faster migrating chain corresponding to the C2a splice variant with an alternative C2 subdomain. In transfected cells, the C2a splice variant was able to assemble into short microfibrils. Together, the results suggest that the C2a splice variant may functionally compensate for the loss of the normal COL6A2 chain when mutations occur in the C2 subdomain.
  Journal of Biological Chemistry 03/2010; 285(13):10005-15. · 4.77 Impact Factor
• Article: Mineralization behavior with mesenchymal stromal cells in a biomimetic hyaluronic acid-based scaffold.

  Cristina Manferdini, Vincenzo Guarino, Nicoletta Zini, Maria Grazia Raucci, Andrea Ferrari, Francesco Grassi, Elena Gabusi, Stefano Squarzoni, Andrea Facchini, Luigi Ambrosio, Gina Lisignoli
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  ABSTRACT: A biomimetic hyaluronic acid (HA)-based polymer scaffold was analysed in vitro for its characteristics and potential to support mineralization as carrier-vehicle. Biomimetic apatite crystal nucleation on the scaffold surface was obtained by a fine control of the pH level that increased ionic solubility thus controlling apatite formation kinetic. Different concentrations of human mesenchymal stromal cells (h-MSCs) were seeded on the scaffold, osteogenesis was induced in the presence or absence of fibroblast growth factor -2 and mineralization was analysed at different time points. We found that only at the highest h-MSCs concentration tested, the cells were uniformly distributed inside and outside the scaffold and proliferation started to decrease from day 7. Electron microscopy analysis evidenced that h-MSCs produced extracellular matrix but did not establish a direct contact with the scaffold. We found mineralized calcium-positive areas mainly present along the backbone of the scaffold starting from day 21 and increasing at day 35. FGF-2 treatment did not accelerate or increase mineralization. Non-biomimetic HA-based control scaffold showed immature mineralized areas only at day 35. Our data demonstrate that the biomimetic treatment of an HA-based scaffold promotes a faster mineralization process suggesting its possible use in clinics as a support for improving bone repair.
  Biomaterials 02/2010; 31(14):3986-96. · 7.40 Impact Factor
• Article: Emerin-prelamin A interplay in human fibroblasts.

  Cristina Capanni, Rosalba Del Coco, Elisabetta Mattioli, Daria Camozzi, Marta Columbaro, Elisa Schena, Luciano Merlini, Stefano Squarzoni, Nadir Mario Maraldi, Giovanna Lattanzi
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  ABSTRACT: Emerin is a nuclear envelope protein that contributes to nuclear architecture, chromatin structure, and gene expression through its interaction with various nuclear proteins. In particular, emerin is molecularly connected with the nuclear lamina, a protein meshwork composed of lamins and lamin-binding proteins underlying the inner nuclear membrane. Among nuclear lamina components, lamin A is a major emerin partner. Lamin A, encoded by the LMNA gene (lamin A/C gene), is produced as a precursor protein (prelamin A) that is post-transcriptionally modified at its C-terminal region where the CaaX motif triggers a sequence of modifications, including farnesylation, carboxymethylation, and proteolytic cleavage by ZMPSTE 24 (zinc metalloproteinase Ste24) metalloproteinase. Impairment of the lamin A maturation pathway causing lamin A precursor accumulation is linked to the development of rare diseases such as familial partial lipodystrophy, MADA (mandibuloacral dysplasia), the Werner syndrome, Hutchinson-Gilford progeria syndrome and RD (restrictive dermopathy). In the present study, we show that emerin and different prelamin A forms influence each other's localization. We show that the accumulation of non-farnesylated as well as farnesylated carboxymethylated lamin A precursors in human fibroblasts modifies emerin localization. On the contrary, emerin absence at the inner nuclear membrane leads to unprocessed (non-farnesylated) prelamin A aberrant localization only. Moreover, we observe that the restoration of emerin expression in emerin-null cells induces the recovery of non-farnesylated prelamin A localization. These results indicate that emerin-prelamin A interplay influences nuclear organization. This finding may be relevant to the understanding of laminopathies.
  Biology of the Cell 04/2009; 101(9):541-54. · 3.60 Impact Factor
• Article: Prelamin A is involved in early steps of muscle differentiation.

  Cristina Capanni, Rosalba Del Coco, Stefano Squarzoni, Marta Columbaro, Elisabetta Mattioli, Daria Camozzi, Anna Rocchi, Katia Scotlandi, Nadir Maraldi, Roland Foisner, Giovanna Lattanzi
  [show abstract] [hide abstract]
  ABSTRACT: Lamin A is a nuclear lamina constituent implicated in a number of human disorders including Emery-Dreifuss muscular dystrophy. Since increasing evidence suggests a role of the lamin A precursor in nuclear functions, we investigated the processing of prelamin A during differentiation of C2C12 mouse myoblasts. We show that both protein levels and cellular localization of prelamin A are modulated during myoblast activation. Similar changes of lamin A-binding proteins emerin and LAP2alpha were observed. Furthermore, prelamin A was found in a complex with LAP2alpha in differentiating myoblasts. Prelamin A accumulation in cycling myoblasts by expressing unprocessable mutants affected LAP2alpha and PCNA amount and increased caveolin 3 mRNA and protein levels, while accumulation of prelamin A in differentiated muscle cells following treatment with a farnesyl transferase inhibitor appeared to inhibit caveolin 3 expression. Our data provide evidence for a critical role of the lamin A precursor in the early steps of muscle cell differentiation.
  Experimental Cell Research 11/2008; 314(20):3628-37. · 3.58 Impact Factor
• Article: Effects of prelamin A processing inhibitors on the differentiation and activity of human osteoclasts.

  Nicoletta Zini, Sofia Avnet, Sonia Ghisu, Nadir Mario Maraldi, Stefano Squarzoni, Nicola Baldini, Giovanna Lattanzi
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  ABSTRACT: Osteoclast differentiation is a complex process involving cytoskeleton and nuclear reorganization. Osteoclasts regulate bone homeostasis and have a key role in bone degenerative processes. Osteolysis and osteoporosis characterize a subset of laminopathies, inherited disorders due to defects in lamin A/C. Laminopathies featuring bone resorption are characterized, at the molecular level, by anomalous accumulation of the unprocessed lamin A precursor, called prelamin A. To obtain a suitable cell model to study prelamin A effects on osteoclasts, prelamin A processing inhibitors FTI-277 or AFCMe were applied to peripheral blood monocytes induced to differentiate towards the osteoclastic lineage. Previous studies have shown that treatment with FTI-277 causes accumulation of non-farnesylated prelamin A, while AFCMe inhibition of prelamin A maturation causes accumulation of a farnesylated form. We demonstrate that monocytes subjected to FTI-277 treatment and mostly those subjected to AFCMe administration, differentiate towards the osteoclastic lineage more efficiently than untreated monocytes, in terms of number of multinucleated giant cells, mRNA expression of osteoclast-related genes and TRACP 5b activity. On the other hand, the bone resorption activity of osteoclasts obtained in the presence of high prelamin A levels is lower with respect to control osteoclasts. This finding may help the understanding of the osteolytic and osteoporotic processes that characterize progeroid laminopathies.
  Journal of Cellular Biochemistry 05/2008; 105(1):34-40. · 2.87 Impact Factor
• Article: Drugs affecting prelamin A processing: effects on heterochromatin organization.

  Elisabetta Mattioli, Marta Columbaro, Cristina Capanni, Spartaco Santi, Nadir M Maraldi, M Rosaria D'Apice, Giuseppe Novelli, Massimo Riccio, Stefano Squarzoni, Roland Foisner, Giovanna Lattanzi
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  ABSTRACT: Increasing interest in drugs acting on prelamin A has derived from the finding of prelamin A involvement in severe laminopathies. Amelioration of the nuclear morphology by inhibitors of prelamin A farnesylation has been widely reported in progeroid laminopathies. We investigated the effects on chromatin organization of two drugs inhibiting prelamin A processing by an ultrastructural and biochemical approach. The farnesyltransferase inhibitor FTI-277 and the non-peptidomimetic drug N-acetyl-S-farnesyl-l-cysteine methylester (AFCMe) were administered to cultured control human fibroblasts for 6 or 18 h. FTI-277 interferes with protein farnesylation causing accumulation of non-farnesylated prelamin A, while AFCMe impairs the last cleavage of the lamin A precursor and is expected to accumulate farnesylated prelamin A. FTI-277 caused redistribution of heterochromatin domains at the nuclear interior, while AFCMe caused loss of heterochromatin domains, increase of nuclear size and nuclear lamina thickening. At the biochemical level, heterochromatin-associated proteins and LAP2 alpha were clustered at the nuclear interior following FTI-277 treatment, while they were unevenly distributed or absent in AFCMe-treated nuclei. The reported effects show that chromatin is an immediate target of FTI-277 and AFCMe and that dramatic remodeling of chromatin domains occurs following treatment with the drugs. These effects appear to depend, at least in part, on the accumulation of prelamin A forms, since impairment of prelamin A accumulation, here obtained by 5-azadeoxycytidine treatment, abolishes the chromatin effects. These results may be used to evaluate downstream effects of FTIs or other prelamin A inhibitors potentially useful for the therapy of laminopathies.
  Experimental Cell Research 03/2008; 314(3):453-62. · 3.58 Impact Factor
• Article: Pre-Lamin A processing is linked to heterochromatin organization.

  Giovanna Lattanzi, Marta Columbaro, Elisabetta Mattioli, Vittoria Cenni, Daria Camozzi, Manfred Wehnert, Spartaco Santi, Massimo Riccio, Rosalba Del Coco, Nadir M Maraldi, Stefano Squarzoni, Roland Foisner, Cristina Capanni
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  ABSTRACT: Pre-lamin A undergoes subsequent steps of post-translational modification at its C-terminus, including farnesylation, methylation, and cleavage by ZMPSTE24 metalloprotease. Here, we show that accumulation of different intermediates of pre-lamin A processing in nuclei, induced by expression of mutated pre-lamin A, differentially affected chromatin organization in human fibroblasts. Unprocessed (non-farnesylated) pre-lamin A accumulated in intranuclear foci, caused the redistribution of LAP2alpha and of the heterochromatin markers HP1alpha and trimethyl-K9-histone 3, and triggered heterochromatin localization in the nuclear interior. In contrast, the farnesylated and carboxymethylated lamin A precursor accumulated at the nuclear periphery and caused loss of heterochromatin markers and Lap2alpha in enlarged nuclei. Interestingly, pre-lamin A bound both HP1alpha and LAP2alpha in vivo, but the farnesylated form showed reduced affinity for HP1alpha. Our data show a link between pre-lamin A processing and heterochromatin remodeling and have major implications for understanding molecular mechanisms of human diseases linked to mutations in lamins.
  Journal of Cellular Biochemistry 01/2008; 102(5):1149-59. · 2.87 Impact Factor
• Article: Prelamin A processing and heterochromatin dynamics in laminopathies.

  Nadir M Maraldi, Elisabetta Mattioli, Giovanna Lattanzi, Marta Columbaro, Cristina Capanni, Daria Camozzi, Stefano Squarzoni, Francesco A Manzoli
  Advances in Enzyme Regulation 02/2007; 47:154-67.
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  Available from: ccmb.res.in

  Article: A pathogenic mechanism leading to partial lipodistrophy and prospects for pharmacological treatment of insulin resistance syndrome.

  Nadir M Maraldi, Cristina Capanni, Elisabetta Mattioli, Marta Columbaro, Stefano Squarzoni, Weena K Parnaik, Manfred Wehnert, Giovanna Lattanzi
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  ABSTRACT: The understanding of a common complex phenotype such as insulin resistance can be favoured by evaluation of monogenic syndromes. Clinical definition, pathogenesis, and therapeutical strategies for the insulin resistance syndrome can thus be improved by the characterization at the molecular genetic level of monogenic forms of lipodystrophies. Here we report experimental evidence on the pathogenic mechanism underlying insulin resistance in a rare form of laminopathy, due to mutation of the LMNA gene coding for lamin A/C, the Dunnigan-type familial partial lipodystrophy (FPLD). The defect, consisting in the intranuclear accumulation of mutant unprocessed precursors of lamin A, reduces the amount of the DNA-bound adipocyte transcription factor sterol regulatory element binding protein 1 (SREBP1) and lowers the peroxisome proliferator-activated receptor (PPARgamma) expression, causing the impairment of pre-adipocyte differentiation. The treatment with the PPARgamma ligand troglitazone (TDZ) is able to rescue the adipogenic program. Since FPLD recapitulates the essential metabolic abnormalities of the common insulin resistance syndrome, the beneficial effects of TDZ on monogenic lipodystrophies might provide a clue as to the future treatment strategies also for the common syndrome of insulin resistance.
  Acta bio-medica: Atenei Parmensis 02/2007; 78 Suppl 1:207-15.
• Chapter: Mitochondrial Pathogenesis of Myopathies Due to Collagen VI Mutations

  Nadir M. Maraldi, Stefano Squarzoni, Patrizia Sabatelli
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  ABSTRACT: Muscle cells are individually surrounded by a basal lamina which interacts with several constituents of the extracellular matrix (ECM), which contributes to the mechanical stability of contractile cells. A major component of the muscular ECM is collagen VI, which forms a microfibrillar network in association with the basal lamina. Mutations in the genes which encode any of the three chains of collagen VI have been reported in Bethlem myopathy and Ullrich congenital muscular dystrophy.
  12/2006: pages 133-144;
• Article: Ultrastructural defects of collagen VI filaments in an Ullrich syndrome patient with loss of the alpha3(VI) N10-N7 domains.

  Stefano Squarzoni, Patrizia Sabatelli, Natascha Bergamin, Pascale Guicheney, Ercan Demir, Luciano Merlini, Giovanna Lattanzi, Andrea Ognibene, Cristina Capanni, Elisabetta Mattioli, Marta Columbaro, Paolo Bonaldo, Nadir Mario Maraldi
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  ABSTRACT: Ultrastructural alterations of collagen VI in cultured fibroblasts and reduced collagen VI immunostaining in the papillary dermis and endomysium were detected in a patient with a mild form of Ullrich congenital muscular dystrophy caused by a COL6A3 gene mutation. The patient had been previously demonstrated to express an alpha3(VI) chain shorter than normal due to skipping of the mutated exon. We show that collagen VI filaments are not organized in a normal network in the extracellular matrix secreted by patient's cultured fibroblasts. Moreover, we demonstrate that in this patient the alpha3(VI) chain is produced in lower amounts and it is almost exclusively represented by the shorter, alternatively spliced N6-C5 isoform. These results suggest that different alpha3(VI) chain isoforms, containing also domains of the N10-N7 region, are required for assembling a proper collagen VI network in the extracellular matrix.
  Journal of Cellular Physiology 02/2006; 206(1):160-6. · 3.87 Impact Factor