Skip to main content
Journal cover image

alphaSU2, an epithelial integrin that binds laminin in the sea urchin embryo.

Publication ,  Journal Article
Hertzler, PL; McClay, DR
Published in: Developmental biology
March 1999

At gastrulation in the sea urchin embryo dramatic cell adhesion changes contribute to primary mesenchyme cell ingression movements and to cell rearrangements during archenteron invagination. At ingression, quantitative adhesion assays demonstrated previously that primary mesenchyme cells (PMCs) change their affinity for neighboring cells, for a fibronectin-like substrate, and for the hyaline layer. To investigate the molecular basis for these and other differential cell affinities at gastrulation, we have identified an integrin that appears to be responsible for specific alterations in cell-substrate adhesion to laminin. During early cleavage stages blastomeres adhere poorly to laminin substrates. Around hatching there is a large increase in the ability of blastomeres to bind to laminin and this increase correlates temporally with the expression of an integrin on the basal surface all blastomeres. PMCs, after undergoing their epithelial-mesenchymal transition, have a strongly reduced affinity for laminin relative to ectoderm cells and, correspondingly, do not stain for the presence of the integrin. We identified the alpha integrin cDNA from Lytechinus variegatus by RT-PCR. Overlapping clones were obtained from a midgastrula cDNA library to provide a complete sequence for the integrin. The composite cDNA encoded a protein that was most similar to the alpha5 subgroup of vertebrate integrins, but there was not a definitive vertebrate integrin homolog. Northern blots and Western immunoblots showed that the sea urchin integrin, which we have named alphaSU2, is present in eggs and during all stages of development. Immunolocalization with specific polyclonal antibodies showed that alphaSU2 first appears on the basal cell surface of epithelia at the midblastula stage, at a time correlating with the increase in adhesive affinity for laminin. The protein remains at high levels on the basal surface of ectoderm cells but is temporarily reduced or eliminated from endoderm cells during their convergent-extension movements. To confirm integrin binding specificity, alphaSU2 was transfected into an alpha-integrin-deficient CHO cell line. alphaSU2-expressing CHO cells bound well to isolated sea urchin basal lamina and to purified laminin. The transfected cells bound weakly or not at all to fibronectin, type I collagen, and type IV collagen. This is consistent with the hypothesis that alphaSU2 integrin functions by binding epithelial cells to laminin in the basal lamina. In vivo, modulation of alphaSU2 integrin expression correlates with critical adhesive changes during cleavage and gastrulation. Thus, this protein appears to be an important contributor to the morphogenetic rearrangements that characterize gastrulation in the sea urchin embryo.

Duke Scholars

Altmetric Attention Stats
Dimensions Citation Stats

Published In

Developmental biology

DOI

EISSN

1095-564X

ISSN

0012-1606

Publication Date

March 1999

Volume

207

Issue

1

Start / End Page

1 / 13

Related Subject Headings

  • Transfection
  • Sequence Homology, Amino Acid
  • Sequence Analysis, DNA
  • Sea Urchins
  • RNA, Messenger
  • Protein Binding
  • Phylogeny
  • Molecular Sequence Data
  • Mesoderm
  • Laminin
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Hertzler, P. L., & McClay, D. R. (1999). alphaSU2, an epithelial integrin that binds laminin in the sea urchin embryo. Developmental Biology, 207(1), 1–13. https://doi.org/10.1006/dbio.1998.9165
Hertzler, P. L., and D. R. McClay. “alphaSU2, an epithelial integrin that binds laminin in the sea urchin embryo.Developmental Biology 207, no. 1 (March 1999): 1–13. https://doi.org/10.1006/dbio.1998.9165.
Hertzler PL, McClay DR. alphaSU2, an epithelial integrin that binds laminin in the sea urchin embryo. Developmental biology. 1999 Mar;207(1):1–13.
Hertzler, P. L., and D. R. McClay. “alphaSU2, an epithelial integrin that binds laminin in the sea urchin embryo.Developmental Biology, vol. 207, no. 1, Mar. 1999, pp. 1–13. Epmc, doi:10.1006/dbio.1998.9165.
Hertzler PL, McClay DR. alphaSU2, an epithelial integrin that binds laminin in the sea urchin embryo. Developmental biology. 1999 Mar;207(1):1–13.
Journal cover image

Published In

Developmental biology

DOI

EISSN

1095-564X

ISSN

0012-1606

Publication Date

March 1999

Volume

207

Issue

1

Start / End Page

1 / 13

Related Subject Headings

  • Transfection
  • Sequence Homology, Amino Acid
  • Sequence Analysis, DNA
  • Sea Urchins
  • RNA, Messenger
  • Protein Binding
  • Phylogeny
  • Molecular Sequence Data
  • Mesoderm
  • Laminin