Hemidesmosomes are complex macromolecular structures which integrate elements of the extracellular matrix and the cytoskeleton of epithelial cells. To characterize cell-matrix interactions in the hemidesmosome, we have made use of 804G cells which possess the unusual ability to assemble hemidesmosomes in vitro. During the course of our studies, we have raised a set of monoclonal antibodies against rat laminin-5, the major structural element comprising 804G matrix. One of these, termed CM6, recognizes the 150 kDa alpha chain of rat laminin-5 and binds the globular (G) domain of intact laminin-5 molecules as determined by rotary shadowing. CM6 antibodies perturb formed hemidesmosomes in 804G cells. In particular, within 1 hour of incubation of 804G cells with CM6 antibodies, colocalization of laminin-5 and alpha 6 beta 4 integrin is lost and by 2 hours, staining generated by hemidesmosomal antibodies appears primarily cytoplasmic in the perinuclear zone. Ultrastructurally, CM6 antibodies first appear to induce detachment of hemidesmosomes from the underlying matrix. Next, portions of the basal cell surface invaginate to form vesicles whose cytoplasmic-facing surface is coated with hemidesmosomes still associated with keratin intermediate filaments. Anchoring filaments extend into the inside compartment of the vesicles. We have also studied the impact of CM6 antibodies on a model system in which the matrix of 804G cells induces de novo assembly of hemidesmosomes in human keratinocytes. This process involves the plasma membrane reorganization of the hemidesmosome associated integrin alpha 6 beta 4 as well as a redistribution of other hemidesmosome components such as the 230 kDa bullous pemphigoid antigen. Pretreatment of 804G matrix with CM6 antibodies blocks such plasma membrane reorganization of hemidesmosome components and inhibits hemidesmosome formation. Our studies indicate a crucial role for the G domain of the alpha chain of laminin-5 in both nucleation of hemidesmosome assembly as well as maintenance of hemidesmosome structural integrity.
Laminin-5 and hemidesmosomes: role of the alpha 3 chain subunit in hemidesmosome stability and assembly
S.E. Baker, S.B. Hopkinson, M. Fitchmun, G.L. Andreason, F. Frasier, G. Plopper, V. Quaranta, J.C. Jones; Laminin-5 and hemidesmosomes: role of the alpha 3 chain subunit in hemidesmosome stability and assembly. J Cell Sci 1 October 1996; 109 (10): 2509–2520. doi: https://doi.org/10.1242/jcs.109.10.2509
Download citation file:
Advertisement
Cited by
JCS Journal Meeting 2023: Imaging Cell Dynamics

Our 2023 Journal Meeting on ‘Imaging Cell Dynamics’ will be held from 14-17 May 2023 in Lisbon, Portugal. We have a limited number of spaces left so sign up now! Registration deadline: 31 March.
Call for papers: Cell and Tissue Polarity
-PolarityCFP.png?versionId=4491)
We are welcoming submissions for our next special issue, which will focus on ‘Cell and tissue polarity’ and will be guest edited by David Bryant. Submission deadline: 15 July.
Webinar: Increasing the visibility and impact of your research
-HUBSwebinar.jpg?versionId=4491)
Would you like to increase the visibility and impact of your research and raise your profile internationally? If so, register for the very practical webinar we are running in association with HUBS on 23 February 2023.
Cell scientist to watch: Gautam Dey

We interviewed Gautam Dey, who became a group leader at EMBL in Heidelberg, Germany, in 2021. His lab investigates the fundamental organisational principles and evolutionary dynamics of the nuclear compartment across eukaryotes.
Mechanisms of eukaryotic transcription termination at a glance

Check out our latest Cell Science at a Glance article and accompanying poster for an overview of the current understanding about the mechanisms of transcription termination by the three eukaryotic RNAPs.