Molecular Medicine Section

Department of Neuroscience, University of Siena

Professor, Director Molecular Medicine Section
Department of Neuroscience
University of Siena, Siena, Italy

Director, Molecular Medicine Unit,
University Hospital of Siena (AOUS), Siena, Italy

Research interests
Research projects
Laboratory members
PhD in Molecular Medicine
Diagnostic activities
Secretary office
0577 234079
0577 234130; 153; 157; 185
0577 234191
0577 234192; 234051
Research Projects
  1. Molecular mechanisms in the organization of specialised domains of the sarcoplasmic reticulum of muscle cells.

    One of the major questions of current research is to define the subcellular localization of many proteins in cells and how they eventually interact to generate complex functional structure. The sarcoplasmic reticulum of muscle cells is a clear example of how vertebrate cells are able to organize distinct subcellular regions where proteins selectively segregate to form specialized functional domains.

    a) mechanisms for delivering proteins to sub-compartments of the sarcoplasmic reticulum.

    The sarcoplasmic reticulum, which represents a complex sub-compartmentalization of smooth ER, appears as a network of tubules and cisternae, mainly devoted to Ca2+ storage. At least two structurally and functionally distinct subdomains have been identified in the sarcoplasmic reticulum, the longitudinal tubules and the terminal cisternae. However, although these domains have been well described in terms of their morphological and biochemical composition, little is known about the mechanisms directing the organization of sarcoplasmic reticulum domains or about targeting or segregation of specific proteins to specific sub-compartments.

    b) molecular mechanism(s) responsible for the interactions between the sarcoplasmic reticulum and myofibrils.

    The sarcoplasmic reticulum is organised to form a sleeve-like structure of intracellular membranes organised around each myofibril. In this context, specialised subdomains of the sarcoplasmic reticulum are precisely aligned with respect to specific regions of the sarcomere/contractile apparatus in a structural arrangement that reflects the optimal positioning of Ca2+ release sites with respect to their target: the myofilaments. We have recently discovered that ank1.5, a small splice variant of the ank1 gene localised on the sarcoplasmic reticulum membrane, is capable of interacting with the C-terminus of Obscurin, a giant sarcomeric protein present in the myofibrils. The interaction between ank1.5 and Obscurin represents the first direct evidence of two proteins that may provide a direct link between the sarcoplasmic reticulum and myofibrils. We are currently extending these studies to identify other components necessary for the assembly of these structures.

    c) confocal and epifluorescence microscopy techniques ( FRAP and FRET) to study protein dynamics and interactions in the sarcoplasmic reticulum.

    Most of the projects carried out in our lab are based on sophisticated methods for understanding localization and dynamic of proteins of interest in living cells. Fluorescent chimeras of proteins of interest are expressed in cultured myoblasts and observed through live imaging. These techniques take advantage of both laser confocal and epifluorescence microscopy using recently developed protocols such as FRAP (fluorescence microscopy after photobleaching), FRET (fluorescence resonance energy transfer) and time lapse imaging. These techniques allow us to follow proteins of interest through myoblast differentiation until they reach their spatial and functional status in highly differentiated cells. FRAP measurements, which measure the level of mobility of specific proteins, may provide indirect evidence on the possible association of the protein being analysed with relatively stable structures of the cell. FRET analyses, on the other hand, can be used to verify interactions between proteins and within protein complexes.

    d) in silico and “wet” cloning of novel muscle-specific genes.

    In addition to study known proteins of the sarcoplasmic reticulum, we are working to the identification of novel muscle specific proteins involved in the organization of this organelle. Recent results from our laboratory support the notion that the intracellular organization of the sarcoplasmic reticulum and of of its subcellular domains with respect to the sarcomere is the result of a series of changes which can be followed during muscle development in vivo as well as during differentiation of muscle cells in vitro. To identify and characterise genes encoding proteins involved in this process we are following two complementary strategies: 1) screening of available microarray data sets looking for genes expressed predominantly in muscle tissues, but of unknown function; 2) molecular cloning by Suppression Subtractive Hybridization (SSH) technique to compare gene expression between cells at different levels of organization of the sarcoplasmic reticulum. Selected genes are being characterized with respect to their localization in muscle cells by confocal fluorescence microscopy and by RNA interference (RNAi) in order to verify their function.

  2. Mechanisms that regulate proliferative and differentiative potentials of human adult stem cells.

    Research on adult stem cells is attracting increasing interest in light of the many biological questions that are linked to stem cells in terms of basic research, but also because stem cells hold great promise for the development of new therapies for a variety of disorders for which a cure is not yet available. Since 2004 our group is participating in the Center for Stem Cell Research of the University of Siena, where our research is currently focused on two main projects:

    1) Characterisation of human mesenchymal stem cells from adult human tissues.
    2) Studies on circulating Endothelial Precursors Cells (EPCs) and their role in different pathological conditions.

    a) Mesenchymal Stem Cells

    Mesenchymal stem cells (MSCs) are multipotent adult stem cells with the ability to differentiate into several cell types including adipose, bone and cartilage cells and represent good candidates for cellular therapy and regenerative medicine. The molecular mechanisms that regulate proliferation and differentiation of MSCs are not known. We are interested in elucidating these mechanisms and to compare the characteristics of the mesenchymal stem cells that we have derived from different sources. We also want to verify the regenerative capacity of these cells by using animal models of pathologies such as cardiac infarction and skeletal muscle injury.

    Although MSCs were originally isolated from bone marrow, similar populations have been reported in other tissues. In our lab, we have isolated and expanded different populations of MSCs from adipose, cardiac and pancreatic tissues and from umbilical cord blood. The phenotype of these cells has been characterised at the level of cell surface antigen expression by FACS analysis and of gene expression profile by RT-PCR. The potential of these cells to differentiate in different cell types, including adipose, cartilage, bone, skeletal and cardiac muscle cells is being tested in a comparative way to verify whether MSCs from different tissues display similar or different capabilities in their differentiative potentials. Molecular analysis will be performed to verify whether these cells can be distinguished in terms of gene expression aiming to define the molecular pathways that govern proliferation and differentiation in adult human stem cells.

    b) Endothelial precursor cells in the pathogenesis of disease states

    Endothelial Progenitor Cells (EPCs) are one example of stem cells present in adults. EPCs are a subtype of circulating, bone marrow derived cells with properties similar to those of embryonic angioblasts contained in peripheral blood of adults. These precursors have the potential to differentiate into mature endothelial cells. A feature of EPCs is their ability to form clusters or colony forming units (CFU’s). The influence of pathological conditions on the number of circulating EPCs has been reported in the literature for patients with risk factors for ischemic cardiovascular disease and other pathologies. Again, in spite of the interest on these cells, they are still poorly characterised and relatively poor information is available. The aim of the current project is to screen a cohort of patients with various pathological conditions and healthy controls using a number of cell surface antigens potentially expressed on stem cells with a view to better define the EPC populations circulating in normal and pathological conditions. The techniques applied in this project include fluorescence-activated cell sorter (FACS) for the analysis of peripheral blood mononucleated cells, cell culture and immuno-fluorescence techniques. Molecular techniques are also being applied to isolated populations of EPC to characterise their profile of gene expression.


1) GIANNINI G., CLEMENTI E., CECI R., MARZIALI G. and SORRENTINO V. Expression of a ryanodine receptor-Ca2+ channel that is regulated by TGFß. 1992. Science 257, 91-94.

2) SORRENTINO V. and VOLPE P. Ryanodine receptors: how many, where and why? 1993. Trends in Pharmacol. Sciences.14, 98-103.

3) GIANNINI G., CONTI A., MAMMARELLA S., SCROBOGNA M. and SORRENTINO V. The ryanodine receptor/Calcium channel genes are widely and differentially expressed in murine brain and peripheral tissues. 1995. Journal of Cell Biology 128, 893-904.

4) OTTINI L., MARZIALI G., CONTI A., CHARLESWORTH A. and SORRENTINO V. Alpha and beta isoforms of ryanodine receptor from chicken skeletal muscle are the homologues of mammalian RyR1 and RyR3. 1996. Biochemical Journal 315, 207-216.

5) CONTI A., GORZA L. and SORRENTINO V. Differential distribution of ryanodine receptor type 3 (RyR3) gene product in mammalian skeletal muscles. 1996. Biochemical Journal 316, 19-23.

6) TARRONI P., ROSSI D., CONTI A. and SORRENTINO V. Expression of the ryanodine receptor type 3 calcium release channel during development and differentiation of mammalian skeletal muscle cells. 1997. Journal of Biological Chemistry 272, 19808-19813.

7) BERTOCCHINI F., OVITT C., CONTI A., BARONE V., SCHOLER H.R., BOTTINELLI R., REGGIANI C. and SORRENTINO V. Requirement for the ryanodine receptor type 3 for efficient contraction in neonatal skeletal muscles. 1997. The EMBO Journal. 16, 6956-6963.

8) BARONE V., BERTOCCHINI F., BOTTINELLI R., PROTASI F., ALLEN P.D., FRANZINI ARMSTRONG C., REGGIANI C. and SORRENTINO V. Contractile impairment and structural alterations of skeletal muscles from knockout mice lacking type 1 and type 3 ryanodine receptors. 1998. FEBS Letters 422, 160-164.

9) SONNLEITNER A., CONTI A., BERTOCCHINI F., SCHINDLER H. and SORRENTINO V. Functional properties of the ryanodine receptor type 3 (RyR3) Ca2+ release channel. 1998. The EMBO Journal. 17, 2790-2798.

10) ISLAM S., LEIBIGER I., LEIBIGER B., ROSSI D., SORRENTINO V., EKSTROM T., WESTERBLAD H., ANDRADE F.H. and BERGGREN P. In situ activation of the type 2 ryanodine receptor in pancreatic beta cells requires cAMP-dependent phosphorylation. 1998. Proc Natl Acad Sci U S A 95, 6145-6150.

11) MARCOLONGO P., BARONE V., PRIORI G., PIROLA B., GIGLIO S., BIASUCCI G., ZAMMARCHI E., PARENTI G., BURCHELL A., BENEDETTI A. and SORRENTINO V. Structure and mutation analysis of the glycogen storage disease type 1b gene. 1998. FEBS Letters 436, 247-50.

12) BARONE V., MASSA O., INTRAVAIA E., BRACCO A., DI MARTINO A., TEGAZZIN V., COZZOLINO S. and SORRENTINO V. Mutation screening of the RYR1 gene and identification of two novel mutations in Italian malignant hyperthermia families. 1999. J. Med. Genetics 36, 115-118.

13) SORRENTINO V. and REGGIANI C. Expression of ryanodine receptor type 3 in skeletal muscle. A new partner in excitation-contraction coupling? 1999. Trends in Cardiovascular Medicine 9, 54-61.

14) FLUCHER B.E., CONTI A., TAKESHIMA H. and SORRENTINO V. Type 3 and Type 1 ryanodine receptors are colocalized in triads of the same mammalian skeletal muscle fibers. 1999. J. Cell. Biology 146, 621-30.

15) CONKLIN M.W., BARONE V., SORRENTINO V. and CORONADO R. Contribution of ryanodine receptor type 3 to Ca(2+) sparks in embryonic mouse skeletal muscle. 1999. Biophysical J. 77, 1394-1403.

16) BALSCHUN D., WOLFER D.P., BERTOCCHINI F., BARONE V., CONTI A., ZUSCHRATTER W., MISSIAEN L., LIPP H.P., FREY U. and SORRENTINO V. Deletion of the ryanodine receptor Type 3 (RyR3) impairs forms of synaptic plasticity and spatial learning. 1999. EMBO J. 18, 5264-5273.

17) SKIROKOVA N., SHIROKOV R., ROSSI D., GONZALEZ A., KIRSCH W.G., GARCIA J., SORRENTINO V. and RIOS E. Spatially segregated control of Ca2+ release in developing skeletal muscle of mice. 1999. J. Physiology, J Physiol (Lond) 521, 483-495

18) CONKLIN M.W., AHERN C.A., VALLEJO P., SORRENTINO V., TAKESHIMA H. and CORONADO R. Comparison of Ca(2+) Sparks Produced Independently by Two Ryanodine Receptor Isoforms (Type 1 or Type 3). 2000. Biophys J. 78, 1777-1785.

19) SORRENTINO V., BARONE V. and ROSSI D. Intracellular Ca2+ release channels in evolution. 2000. Curr. Opin. Gen. Dev. 10, 662-667.

20) PRIORI S.G., NAPOLITANO C., TISO N., MEMMI M., VIGNATI G., BLOISE R., SORRENTINO V. and DANIELI G.A. Mutations in the cardiac Ryanodine Receptor gene (hRyR2) underlie Catecholaminergic Polymorphic Ventricular Tachycardia. 2001. Circulation 103, 196-200.

21) BULTYNCK G., DE SMET P., ROSSI D., CALLEWAERT G., MISSIAEN L., SORRENTINO V., DE SMEDT H. and PARYS J. B. Characterisation and mapping of the 12 kDa FK506-binding protein (FKBP12)-binding site on different isoforms of the ryanodine receptor and of the inositol 1,4,5-trisphosphate receptor. 2001. Biochemical J. 354, 413-422.

22) ROSSI R., BOTTINELLI R., SORRENTINO V. and REGGIANI C. Response to caffeine and ryanodine receptor isoforms in mouse skeletal muscles. 2001. Am J Physiol Cell Physiol. 281, C585-C594.

23) SORRENTINO V. and R. RIZZUTO. Molecular genetics of Ca2+ stores and intracellular Ca2+ signalling. 2001. Trends in Pharmacol. Sciences. 22, 459-464.

24) FULCERI R., ROSSI R., BOTTINELLI R., CONTI A., INTRAVAIA E., GALIONE A., BENEDETTI A., SORRENTINO V. and REGGIANI C. Ca2+ release induced by cyclic ADP ribose in mice lacking type 3 ryanodine receptor. 2001. Biochem Biophys Res Commun. 288, 697-702

25) SIMEONI I., ROSSI D., ZHU X., GARCÍA J., VALDIVIA H.H. and SORRENTINO V. Imperatoxin A (IpTx(a)) from Pandinus imperator stimulates [(3)H]ryanodine binding to RyR3 channels. 2001. FEBS Letters 508, 5-10.

26) LÖHN M., JESSNER W., FÜRSTENAU M., WELLNER M., SORRENTINO V., HALLER H., LUFT F.C. and GOLLASCH M. Regulation of Calcium Sparks and Spontaneous Transient Outward Currents by RyR3 in Arterial Vascular Smooth Muscle Cells. 2001. Circulation Research 89, 1051–1057.

27) BULTYNCK G., ROSSI D., CALLEWAERT G., MISSIAEN L., SORRENTINO V., PARYS J.B. and DE SMEDT H. The Conserved Sites for the FK506-binding Proteins in Ryanodine Receptors and Inositol 1,4,5-Trisphosphate Receptors Are Structurally and Functionally Different . 2001. J. Biol. Chem. 276, 47715-47724.

28) MATYASH M., MATYASH V., NOLTE C., SORRENTINO V. and KETTENMANN H. Requirement of functional ryanodine receptor type 3 for astrocyte migration. 2002. FASEB J. 16, 84-86

29) MIRONNEAU M., MACREZ N., MOREL J.L., SORRENTINO V. AND MIRONNEAU C. Identification and function of ryanodine receptor subtype 3 in non-pregnant mouse myometrial cells. 2002. J. Physiology 538, 707–716

30) NABHANI T., ZHU X., SIMEONI I., SORRENTINO V., VALDIVIA H.H. and GARCÍA J. Imperatoxin a enhances Ca (2+) release in developing skeletal muscle containing ryanodine receptor type 3. 2002. Biophysical J. 82, 1319-1328.

31) BARONE F., GENAZZANI A.A., CONTI A., CHURCHILL G.C., PALOMBI F., ZIPARO E., SORRENTINO V., GALIONE A. and FILIPPINI A. A pivotal role for cADPR-mediated Ca2+ signalling: regulation of endothelin-induced contraction in peritubular smooth muscle cells. 2002. FASEB J. 16, 697-705.

32) ROSSI D., SIMEONI I., MICHELI M., BOOTMAN M., LIPP P., ALLEN P.D. and SORRENTINO V. RyR1 and RyR3 Isoforms provide distintct intracellular Ca2+ signals in HEK 293 cells. 2002. J Cell Sci. 115, 2497-2504

33) GALLI L., ORRICO A., COZZOLINO S., PIETRINI V., TEGAZZIN V. and SORRENTINO V. Mutations in the RYR1 gene in Italian patients at risk for Malignant Hyperthermia: evidence for a cluster of novel mutations in the C-terminal region. 2002. Cell Calcium 32, 143-151

34) SALANOVA M., PRIORI G., BARONE V., INTRAVAIA E., FLUCHER B., CIRUELA F., MCILHINNEY R.A.J., PARYS J.B., MIKOSHIBA K. AND SORRENTINO V. Homer proteins and InsP3 receptors co-localize in the longitudinal sarcoplasmic reticulum of skeletal muscle fibers. 2002. Cell Calcium 32, 193-200.

35) ROSSI D. and SORRENTINO V. Molecular genetics of ryanodine receptors / Ca2+ release channels. 2002. Cell Calcium 32, 307-319

BAGNATO P., BARONE V., ROSSI D. AND SORRENTINO V. Binding of an Ankyrin-1 isoform to the C-terminus of Obscurin identifies a molecular link between the sarcoplasmic reticulum and myofibrils in striated muscles. 2003. J. Cell. Biology 160,245-253.