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Harris Laboratory
Ann Harris Group
The main interests of the group centre on the basic defect in cystic
fibrosis (CF). We are tackling two important questions that are
central to the pathology of the disease: First, what are the genetic
elements that confer tissue specificity and temporal regulation
on expression of the CFTR gene, that when mutated causes CF?
Second, why are CF respiratory and digestive systems obstructed
by mucous secretions? Progress on these topics could make a
significant contribution to the efficacy of treatments for CF, either
by gene therapy or by pharmacological means.
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Regulation of expression of the CFTR gene. The cystic fibrosis
transmembrane conductance regulator (CFTR) gene shows a
complex pattern of expression, with temporal and spatial
regulation that is not accounted for by elements in the promoter.
Using a combined approach of DNase1 hypersensitive site
(DHS) mapping and comparative genomics we have identified
candidate regulatory elements flanking the gene within introns.
The major focus of current research is to determine which of these
DHS contain important regulatory elements for CFTR and how
they function together in vivo. We are also evaluating changes in
chromatin structure that accompany CFTR gene expression.
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Developmental regulation of CFTR expression. The abundance
of CFTR mRNA in the respiratory epithelium falls dramatically
during gestation and relative low levels are evident after birth.
This is an enigma since the primary site of CF pathology is in the
lung. We are investigating the mechanism of the down-regulation
of CFTR expression and asking whether recruitment of alternative
5' exons play a role in this process.
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Mucins and CF. The failure to clear mucous secretions from
epithelial surfaces remains a major problem in CF treatment. Not only
are mucin deposits a significant cause of tissue damage but also
contribute to the relative inefficiency of gene therapy protocols. We
aim to establish the biochemical basis of the CF-associated mucin
abnormailities. We have determined that the O-glycosylation of
mucins, which affects their biochemical and biophysical properties
is not altered by the presence mutant CFTR. We are now concentrating
on the mechanisms of cleavage and release of membrane-tethered
mucins and their role in CF pathology.
Selected Recent Publications
Silverman, H.S., Sutton-Smith, M., McDermott, K., Heal, P., Leir, S.H.,
Hollingsworth, M.A., Morris, H.R., Dell, A., Harris, A. (2003) The contribution
of tandem repeat number to the O-glycosylation of mucins. Glycobiology, 13:
265-277
Mouchel, N., Broackes-Carter, F., Harris, A. (2003) Alternative 5' exons of the
CFTR gene show developmental regulation. Hum. Mol.Genet. 12: 759-769.
Williams, S.H., Mouchel, N., Harris, A. (2003) A comparative genomic analysis
of the cow, pig, and human CFTR genes identifies potential intronic regulatory
elements. Genomics 81: 628-639.
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Williams, S.H., Sahota, V., Palmai-Pallag, T., Tebbutt, S.J., Walker, J., Harris,
A. (2003) Evaluation of gene targeting by homologous recombination in ovine
somatic cells. Molec. Reprod. and Devel. 66: 155-125.
Mouchel, N., Henstra, S.A., McCarthy, V.A., Williams, S.H., Phylactides, M.,
Harris, A. (2004) HNF1alpha is involved in regulation of expression of the CFTR
gene. Biochemical Journal. 378: 909-918.
Leir, S.H., Parry, S., Palmai-Pallag, T., Morris, H.R., Dell, A., Harris, A. (2005)
Mucin glycosylation and sulphation in airway epithelial cells is not influenced
by CFTR expression. Am. J. Resp. Cell and Mol. Biol. 32(5): 453-61.
Palmai-Pallag, T., Khodabukus, N., Kinarsky, L., Leir, S-H., Sherman, S.,
Hollingsworth, M.A., and Harris, A. (2005) The role of the SEA (sea urchin
sperm protein, enterokinase and agrin) - module in cleavage of membrane-
tethered mucins. FEBS J. 272:2901-11.
Shiraga, T., Winpenny, J., Hollingsworth, M.A., Harris, A. (2005) Evaluation of
potential regulatory elements in two DNase I hypersensitive sites in the MUC1
gene promoter. Exp. Cell Research. 308:41-52.
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