Integrin alpha 6B beta 1 is involved in kidney tubulogenesis in vitro.
Laminin-1 has previously been shown to be of major importance for the development of kidney tubules. Antibodies against fragments E8 and E3 of laminin-1 perturb kidney development in vitro. We here studied expression of integrins alpha 6 beta 1 and alpha 6 beta 4, two known laminin receptors, during kidney development. Integrin beta 1 subunit could be detected by immunofluorescence on all cell types of embryonic mouse kidney, but we could not detect integrin beta 4 subunit in embryonic kidney by immunofluorescence or by in situ hybridization. The presence of integrin alpha 6 subunit in all epithelia of embryonic kidney was demonstrated by immunofluorescence and by in situ hybridization. RT-PCR showed that alpha 6B is the major splice variant in embryonic kidney. During in vitro conversion of nephrogenic mesenchyme to epithelial tubules, a strong increase in the expression of the 6 kb mRNA for alpha 6 integrin subunit was seen by northern blotting at the onset of epithelial morphogenesis, on day two of culture. Immunoprecipitation of extracts from embryonic kidney with antibodies against alpha 6 subunit yielded bands corresponding to the expected size of beta 1 integrin subunit but not of beta 4 subunit. Monoclonal antibodies against either alpha 6 or beta 1 subunit but not against E-cadherin blocked kidney tubulogenesis in vitro. This suggests that integrin alpha 6B beta 1 is involved in kidney tubulogenesis in vitro. Another possibility is that the antibodies against integrin alpha 6 and beta 1 subunit cause abnormal signalling by the integrin.
Falk
M
M
Department of Animal Physiology, Uppsala University, Biomedical Center, Uppsala, Sweden.
Salmivirta
K
K
Durbeej
M
M
Larsson
E
E
Ekblom
M
M
Vestweber
D
D
Ekblom
P
P
D000818:Animals; D000906:Antibodies; D015152:Blotting, Northern; D015820:Cadherins / Q000276:immunology / Q000502:physiology; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D039121:Integrin alpha6beta1; D019012:Integrin beta1 / Q000502:physiology*; D016023:Integrins / Q000276:immunology / Q000502:physiology*; D007684:Kidney Tubules / Q000196:embryology*; D051379:Mice; D016133:Polymerase Chain Reaction; D017474:Receptors, Laminin / Q000502:physiology*
D000906:Antibodies; D015820:Cadherins; D039121:Integrin alpha6beta1; D019012:Integrin beta1; D016023:Integrins; D017474:Receptors, Laminin