Franca Cambi, M.D., Ph.D.
MD, University of Florence, Medical School, Florence, Italy, PhD, Neuroscience University La Sapienza, Rome, Italy.
Dr. Cambi's laboratory is focused upon oligodendrocyte cell biology, regulation of alternative splicing of genes expressed by differentiating oligodendrocytes and the molecular determinants that regulate oligodendrocyte function in maintaining myelin and axonal integrity during development, in inherited myelin disorders and in injury models.
Oligodendrocytes, the myelin forming cells of the central nervous system differentiate from progenitor cells in the immediate post-natal period and produce large amount of myelin and myelin specific proteins. Oligodendrocytes generate functionally diverse protein species through temporally regulated alternative splicing of myelin specific genes. A major myelin protein is proteolipid protein (PLP) which is comprised of two alternatively spliced products, PLP and DM20. The mechanisms that regulate spatial and temporal regulation of alternative splicing in oligodendrocytes are critically important for oligodendrocyte functions and brain development and function. Mutations that impair regulatory elements of PLP alternative splicing or defects in splicing factors cause abnormalities of myelin and axonal function and integrity. We have shown that mutations that impair PLP alternative splicing in humans cause developmental and neurodegenerative disorders characterized by axonal degeneration and loss. We have identified and characterized novel regulatory sequences and the role of splicing factors in the alternative splicing of PLP. Current projects in the laboratory explore: 1) the cis-acting elements and the splicing factors that regulate PLP alternative splicing in differentiating oligodendrocytes, 2) the molecular components that link signal transduction and regulation of PLP/DM20 alternative splicing, 3) the cellular consequences that PLP mutations have on myelin and axon integrity in vivo in a novel knockin mouse model that carries deletion of an intronic splicing enhancer identified in human disease. The mouse shows motor deficits and myelin abnormalities. We are in the process of investigating axonal integrity and transport and the molecular determinants of axo-glial interactions, 4) future directions are to explore the role of PLP missplicing in injury models, such as cord injuries and inflammatory disorders.
The laboratory uses primary cell cultures of rat oligodendrocytes and immortalized oligodendrocyte cell lines as the experimental system in which to identify regulatory elements and splicing factors and to investigate the efficacy of RNAi in correcting PLP defects. In vivo studies are conducted in a knockin mouse model that carries a defect in PLP alternative splicing. In collaboration with Dr. Saatman, we are performing axon transport studies. Techniques used in the laboratory are: primary cell cultures and organotypic cultures, RT-PCR, proteomics, quantitative immunoblotting, immunocytochemistry, transfections, RNAi, gene expression, motor and behavioral studies.
Garbern J, Cambi F, Tang X-M, et al. PLP protein is necessary in both central and peripheral myelin. Neuron 1997;19:205-218.
Tang X-M, Strocchi P, Cambi F. Changes in the activity of cdk2 and cdk5 accompany differentiation of rat primary oligodendrocytes. J Cell Biochem 1998;68:128-137.
Tang X-M, Beesley J, Grinspan J, Seth P, Kamholz J, Cambi F. Cell cycle arrest induced by p27 is not sufficient to induce oligodendrocyte differentiation. J Cell Biochem, 1999;76:270-279.
Mars T, Yu JK, Tang XM, Miranda A, Grubic Z, Cambi F, King MP. Differentiation of glial cells and motor neurons during development of the neuromuscular junction in co-cultures of rat spinal cord explant and human muscle. J Comp Neurology, 2001;438(2):239-51.
Huang Z, Tang X-M, Cambi F. Differentiation of oligodendrocytes is associated with loss of expression of the retinoblastoma protein. Mol & Cell Neurosci, 2002;19:250-262.
Hobson G, Huang Z, Stabley D, Sperle K, Cambi F. A PLP splicing abnormality is associated with an unusual presentation of PMD. Ann Neurol, 2002; 52:477-488.
Wang E, Huang Z, Hobson G, Dimova N, Sperle K, A McCullough and Cambi F. PLP1 alternative splicing in differentiating oligodendrocytes: characterization of an exonic splicing enhancer. J Cell Biochem 2006; 97:999-1016.
Hobson G, Huang Z, Sperle K, Sistermans E, Rogan P, Garbern J, Kolodny E, Naidu S and Cambi F. Analysis of the contribution of splice site strength in the regulation of proteolipid protein and DM20 alternative splicing in differentiating oligodendrocytes in vitro. Hum Mutat 27:69-77, 2006.
Sabet A, Li J, Ghandour K, Pu Q, Wu X, Kamholz J, Shy M and Cambi F. Skin biopsies demonstrate MPZ splicing abnormalities in CMT1B. Neurology 67:1141-1146, 2006.
Wang E, Dimova N, and Cambi F. PLP/DM20 ratio is regulated by hnRNPH and F and a novel G-rich enhancer in oligodendrocytes. Nucleic Acids Research 2007; 35: 4164-78.
Wang E, Dimova N, Sperle K, Huang Z, Lock L, McCulloch MC, Edgar JM, Hobson G and Cambi F. Deletion of a splicing enhancer disrupts PLP/DM20 ratio and myelin stability. Exp Neurol. 2008 Dec;214(2):322-30, 2008.
Wang E and Cambi F. Heterogeneous nuclear ribonucleoproteins H and F regulate the proteolipid protein/DM20 ratio by recruiting U1 small nuclear ribonucleoprotein through a complex array of G runs. J Biol Chem 2009, 284(17):11194-204. Epub 2009 Feb 25.
Bargagna-Mohan P, Paranthan R, Hamza A, Dimova N, Trucchi B, Srinivasan S, Elliott G, Zhu H, Zhan C, Lau D, Cambi F & Mohan R. Withaferin A. Targets Intermediate Filaments GFAP and Vimentin in a Model of Retinal Gliosis. EPub J Biol Chem. 2010 Jan 4.
Department of Neurology
Tel: (859) 323-5683