MUCOUS CELL DIFFERENTIATION

Project: Research project

Project Details

Description

Mucociliary functions of respiratory tract epithelium play a very important
role in pulmonary defense. Vitamin A or its analogs (retinoids) is
required for the expression of these differentiated functions. In vitamin
A deficiency, the epithelium changes to a squamous keratinizing one
(squamous metaplasia). Both in vivo and in vitro organ culture studies
show that the addition of vitamin A or other retinoids can convert the
squamous epithelium to a normal mucociliary one. Excess vitamin A can
convert even the stratified skin epithelium to a one containing
mucus-secreting granules (mucous cell metaplasia). However, the nature of
mucociliary differentiation and the mechanism by which retinoid controls
the expression of these differentiated functions are still unknown. An
interdisciplinary approach is proposed to investigate the nature of
retinoid-responsive mucous cell differentiation in cultured hamster
tracheal epithelial (HTE) cells. We have developed a serum-free medium
that permits the growth and differentiation of protease-dissociated
respiratory tract epithelial cells, including HTE cells, on collagen gel
substrata. Vitamin A or other retinoids is required in HTE culture to
induce mucous cell differentiation and ciliogenesis. Based on the
preliminary studies, it is proposed that retinoids regulate mucous cell
differentiation, especially the synthesis of mucin core protein, apomucin,
at the genetic level in the squamous basal cells. To test this hypothesis
and examine the mechanisms of vitamin A regulation at the genetic and
biochemical levels, it will be necessary to develop genetic and
immunological probes for mucin. Development of these probes will be
facilitated by the well-defined culture system for HTE cells. Monoclonal
antibodies specific for hamster tracheal mucin and apomucin will be
developed for monitoring the stages of mucin biosynthesis during the
differentiation. cDNA probes to retinoid-responsive genes, in particular
cDNA complementary to apomucin, will be isolated. The cDNA library of HTE
cells cultured in the presence of retinoid will be developed and screened
with oligonucleotide probes corresponding to apomucin sequence or vitamin
A-responsive genes. Mabs will be used to immunoprecipitate polysome
fractions enriched with apomucin mRNA. Furthermore, a recently developed
biphasic culture chamber (the Whitcutt chamber) which enhances the polarity
of differentiation of cultured HTE cells similar to in vivo, will be used
to identify the precursor cell type involved in retinoid-reponsiove mucous
cell differentiation in vitro.
StatusFinished
Effective start/end date4/1/875/31/06

Funding

  • National Institutes of Health: $286,994.00
  • National Institutes of Health
  • National Institutes of Health: $310,010.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $302,954.00
  • National Institutes of Health
  • National Institutes of Health: $295,105.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $317,251.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $232,175.00
  • National Institutes of Health

ASJC

  • Medicine(all)

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