We have recently shown that the laminin-binding integrin receptor, alpha 6 beta 1, is prominently expressed in the developing chick retina, and its expression and activity are regulated during development on both retinal ganglion cells and other neural retinal cells. In the present study, we show that antibodies specific for the extracellular portion of the chick alpha 6 subunit dramatically inhibit interactions in vitro between embryonic day 6 neural retinal cells and laminin, showing that alpha 6 beta 1 functions as an important laminin receptor on developing retinal neurons. In previous work, we showed that alpha 6 mRNA levels on retinal ganglion cells decrease dramatically after E6 during the period that RGC axons innervate the optic tectum. In the present study, we show decreases in alpha 6 mRNA are not prevented by ablation of the optic tectum, indicating that tectal contact is not the major cause of this decrease. Within the embryonic retina, the alpha 6 subunit is codistributed, in part, with laminin, suggesting that it functions as a laminin receptor during retina development in vivo. Furthermore, two isoforms of the alpha 6 protein with distinct cytoplasmic domains generated by differential splicing have quite different distribution patterns in the retina, suggesting that these two isoforms may have different functions during retinal development.

Adler
R.
,
Jerdan
J.
,
Hewitt
A. T.
(
1985
)
Responses of cultured neural retinal cells to substratum-bound laminin and other extracellular matrix molecules.
Dev. Biol
112
,
100
114
Bodary
S. C.
,
Napier
M. A.
,
McLean
J. W.
(
1989
)
Expression of recombinant platelet glycoprotein IIb/IIIa results in a functional fibrinogen-binding complex.
J. Biol. Chem
264
,
18859
18862
Bottenstein
J. E.
,
Skaper
S. D.
,
Varon
S.
,
Sato
J.
(
1980
)
Selective survival of neurons from chick embryo sensory ganglionic dissociates by use of a defined, serum-free medium.
Exp. Cell Res
125
,
183
190
Carter
W. G.
,
Wayner
E. A.
,
Bouchard
T. S.
,
Kaur
P.
(
1990
)
The role of integrins2 1and 31 in cell-cell and cell-substrate adhesion of human epidermal cells.
J. Cell Biol
110
,
1387
1404
Chan
B. M. C.
,
Hemler
M. E.
(
1993
)
Multiple functional forms of the integrin VLA-2 can be derived from a single2 cDNA clone: Interconversion of forms induced by an anti-1 antibody.
J. Cell Biol
120
,
537
543
Chang
S.
,
Rathjen
F. G.
,
Raper
J. A.
(
1987
)
Extension of neurites on axons is impaired by antibodies against specific neural cell surface glycoproteins.
J. Cell Biol
104
,
355
362
Chomczynski
P.
,
Sacchi
N.
(
1987
)
Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction.
Anal. Biochem
162
,
156
159
de Curtis
I.
(
1991
)
Neuronal interactions with extracellular matrix.
Curr. Opin. Cell Biol
3
,
824
831
Halfter
W.
,
Fua
C. S.
(
1987
)
Immunohistochemical localization of laminin, neural cell adhesion molecule, collagen type IV and T-61 antigen in the embryonic retina of the japanese quail by in vivo injection of antibodies.
Cell Tissue Res
249
,
487
496
Jessell
T. M.
(
1988
)
Adhesion molecules and the hierarchy of neural development.
Neuron
1
,
3
13
Kallunki
P.
,
Sainio
K.
,
Eddy
R.
,
Byers
M.
,
Kallunki
T.
,
Saviola
H.
,
Beck
K.
,
Hirvonen
H.
,
Shows
T.
,
Tryggvason
K.
(
1992
)
A truncated laminin chain homologous to the B2 chain: Structure, spatial expression and chromosomal assignment.
J. Cell Biol
119
,
679
693
O'Rear
J. J.
(
1992
)
A novel laminin B1 chain variant in avian eye.
J. Biol. Chem
267
,
20555
20557
Rager
G. H.
(
1980
)
Development of the retinotectal projection in the chicken.
Adv. Anat. Embryol. Cell Biol
63
,
1
92
Sanes
J. R.
(
1989
)
Extracellular matrix molecules that influence neural development.
Annu. Rev. Neurosci
12
,
491
516
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