Cell Biology – Immunology – Pathology
Kidney International (2003) 63, 1321–1337; doi:10.1046/j.1523-1755.2003.00870.x
Distinct distribution of specific members of protein 4.1 gene family in the mouse nephron
Mohamed Ramez, Marcel Blot-Chabaud, Françoise Cluzeaud, Sumita Chanan, Michael Patterson, Loren D Walensky1, Shirin Marfatia, Anthony J Baines, Joel A Chasis, John G Conboy, Narla Mohandas and Philippe Gascard
Department of Subcellular Structure, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California; INSERM U478, Institut Fédératif de Recherche "Cellules Epithéliales," Faculté de Médecine X. Bichat, Paris, France; Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland; New York Blood Center, New York, New York; Department of Biosciences, University of Kent, Canterbury, England, United Kingdom
Correspondence: Philippe Gascard, Ph.D., Staff Scientist, Department of Subcellular Structure, Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail stop 74-157, Berkeley, CA 94720. E-mail PDGascard@lbl.gov
1Dr. Walensky's present address is Department of Cancer Immunology and AIDS, Dana Farber Cancer Institute, Harvard Medical School, Boston, Massachussetts 02115.
Received 26 August 2002; Revised 24 October 2002; Accepted 21 November 2002.
Abstract
Distinct distribution of specific members of protein 4.1 gene family in the mouse nephron.
Background
Protein 4.1 is an adapter protein that links the actin cytoskeleton to various transmembrane proteins. These 4.1 proteins are encoded by four homologous genes, 4.1R, 4.1G, 4.1N, and 4.1B, which undergo complex alternative splicing. Here we performed a detailed characterization of the expression of specific 4.1 proteins in the mouse nephron.
Methods
Distribution of renal 4.1 proteins was investigated by staining of paraformaldehyde-fixed mouse kidney sections with antibodies highly specific for each 4.1 protein. Major 4.1 splice forms, amplified from mouse kidney marathon cDNA, were expressed in transfected COS-7 cells in order to assign species of known exon composition to proteins detected in kidney.
Results
A 105 kD 4.1R splice form, initiating at ATG-2 translation initiation site and lacking exon 16, but including exon 17B, was restricted to thick ascending limb of Henle's loop. A 95 kD 4.1N splice form, lacking exons 15 and 17D, was expressed in either descending or ascending thin limb of Henle's loop, distal convoluted tubule, and all regions of the collecting duct system. A major 108 kD 4.1B splice form, initiating at a newly characterized ATG translation initiation site, and lacking exons 15, 17B, and 21, was present only in Bowman's capsule and proximal convoluted tubule (PCT). There was no expression of 4.1G in kidney.
Conclusion
Distinct distribution of 4.1 proteins along the nephron suggests their involvement in targeting of selected transmembrane proteins in kidney epithelium and, therefore, in regulation of specific kidney functions.
Keywords:
kidney, nephron, cytoskeleton, protein 4.1
