BIOSYNTHETIC ARREST OF MUTANT CFTR

  • Gendler, Sandra J (PI)
  • Xiu, Chang (PI)
  • Ghanbari, Ray (PI)
  • Hanrahan, John (PI)
  • Clapham, David (PI)
  • Riordan, John (PI)

Project: Research project

Project Details

Description

More than 90% of CF patients have at least one deltaF508 allele of the
CFTR gene. The objective "Biosynthetic Arrest of Mutant CFTR' is to gain
a complete understanding of the biosynthetic block and mislocalization
of the deltaF508 CFTR protein. This information will facilitate the
development of practical approaches to overcoming the biosynthetic arrest
of the major CF-causing mutation and several other less frequent ones
which also compromise biosynthetic processing. This overall objective
will be pursued via four specific aims. In Specific Aim I, we shall
flesh out our present critical but rudimentary knowledge that deltaF508
CFTR is blocked at the level of the endoplasmic reticulum (ER) and that
it is at least some residual function. Confocal and electron microscopy
will be used to precisely determine the localization; inherent activity
of the molecule will be quantitatively assessed both after its
purification and in isolated ER. Monoclonal antibodies will be generated
to distinguish the biosynthetically immature and mature forms of CFTR so
that the maturation process can be readily monitored. Specific Aim II
will investigate the role of chaperones in CFTR biosynthesis. The
detection of any potential differential interactions between a chaperone
and wild-type and deltaF508 CFTR will provide a target to manipulate to
alleviate the biosynthetic arrest. Elucidation of the details of the
interaction with calnexin which has already been identified will be
intensively pursued. Since the failure of a calnexin-CFTR complex to
dissociate seems to contribute to the ER retention of deltaF508, ways of
avoiding or dissociating this complex will be sought. Because
oligosaccharides are involved in complex formation, glycosylation
inhibitors will be tested. In Specific Aim III, several other ways of
getting at least some of the deltaF508 protein past the block will be
investigated. We shall test the effects of antibodies, laser irradiation
and nucleotide analogs. Manipulations which are affective in getting
deltaF508 CFTR to the surface of cultured cells will be evaluated in
transgenic mice expressing only that allele of CFTR to determine if
testing in patients of that genotype is appropriate. Specific Aim IV to
identify and characterize other disease-causing mutations which
compromise protein maturation should be of most benefit by providing
additional insights into aspects of the normal process which may not be
revealed by studying just the wild-type and deltaF508 CFTR molecules.
StatusFinished
Effective start/end date9/30/948/31/97

Funding

  • National Institute of Diabetes and Digestive and Kidney Diseases
  • National Institute of Diabetes and Digestive and Kidney Diseases

ASJC

  • Medicine(all)

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