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The laminin alpha chains: expression, developmental transitions, and chromosomal locations of alpha1-5, identification of heterotrimeric laminins 8-11, and cloning of a novel alpha3 isoform.

Miner JH, Patton BL, Lentz SI, Gilbert DJ, Snider WD, Jenkins NA, Copeland NG, Sanes JR - J. Cell Biol. (1997)

Bottom Line: Interspecific backcross mapping of the five alpha chain genes revealed that they are distributed on four mouse chromosomes.Finally, we identified a novel full-length alpha3 isoform encoded by the Lama3 gene, which was previously believed to encode only truncated chains.Together, these results reveal remarkable diversity in BL composition and complexity in BL development.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.

ABSTRACT
Laminin trimers composed of alpha, beta, and gamma chains are major components of basal laminae (BLs) throughout the body. To date, three alpha chains (alpha1-3) have been shown to assemble into at least seven heterotrimers (called laminins 1-7). Genes encoding two additional alpha chains (alpha4 and alpha5) have been cloned, but little is known about their expression, and their protein products have not been identified. Here we generated antisera to recombinant alpha4 and alpha5 and used them to identify authentic proteins in tissue extracts. Immunoprecipitation and immunoblotting showed that alpha4 and alpha5 assemble into four novel laminin heterotrimers (laminins 8-11: alpha4beta1gamma1, alpha4beta2gamma1, alpha5beta1gamma1, and alpha5beta2gamma1, respectively). Using a panel of nucleotide and antibody probes, we surveyed the expression of alpha1-5 in murine tissues. All five chains were expressed in both embryos and adults, but each was distributed in a distinct pattern at both RNA and protein levels. Overall, alpha4 and alpha5 exhibited the broadest patterns of expression, while expression of alpha1 was the most restricted. Immunohistochemical analysis of kidney, lung, and heart showed that the alpha chains were confined to extracellular matrix and, with few exceptions, to BLs. All developing and adult BLs examined contained at least one alpha chain, all alpha chains were present in multiple BLs, and some BLs contained two or three alpha chains. Detailed analysis of developing kidney revealed that some individual BLs, including those of the tubule and glomerulus, changed in laminin chain composition as they matured, expressing up to three different alpha chains and two different beta chains in an elaborate and dynamic progression. Interspecific backcross mapping of the five alpha chain genes revealed that they are distributed on four mouse chromosomes. Finally, we identified a novel full-length alpha3 isoform encoded by the Lama3 gene, which was previously believed to encode only truncated chains. Together, these results reveal remarkable diversity in BL composition and complexity in BL development.

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Schematic summary of kidney development,  and expression patterns of  the laminin α chains in various nephron segment BLs.  The laminin α and β chains  expressed in the developing  glomerular BL (GBM) and  its progenitors are boxed.  See text for details.
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Figure 7: Schematic summary of kidney development, and expression patterns of the laminin α chains in various nephron segment BLs. The laminin α and β chains expressed in the developing glomerular BL (GBM) and its progenitors are boxed. See text for details.

Mentions: We next used our panel of antisera to ask when developing BLs acquire their complement of laminin α chains. Based on the studies of adult organs detailed above, and on the fact that laminins have been implicated as important in renal development and function (Klein et al., 1988; Noakes et al., 1995), we focused on kidney for this analysis. In fact, we found a complex and dynamic pattern of laminin α chain expression in the BLs of the developing nephron. To document these results, it is first necessary to summarize the main stages of nephrogenesis (Fig. 7).


The laminin alpha chains: expression, developmental transitions, and chromosomal locations of alpha1-5, identification of heterotrimeric laminins 8-11, and cloning of a novel alpha3 isoform.

Miner JH, Patton BL, Lentz SI, Gilbert DJ, Snider WD, Jenkins NA, Copeland NG, Sanes JR - J. Cell Biol. (1997)

Schematic summary of kidney development,  and expression patterns of  the laminin α chains in various nephron segment BLs.  The laminin α and β chains  expressed in the developing  glomerular BL (GBM) and  its progenitors are boxed.  See text for details.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139892&req=5

Figure 7: Schematic summary of kidney development, and expression patterns of the laminin α chains in various nephron segment BLs. The laminin α and β chains expressed in the developing glomerular BL (GBM) and its progenitors are boxed. See text for details.
Mentions: We next used our panel of antisera to ask when developing BLs acquire their complement of laminin α chains. Based on the studies of adult organs detailed above, and on the fact that laminins have been implicated as important in renal development and function (Klein et al., 1988; Noakes et al., 1995), we focused on kidney for this analysis. In fact, we found a complex and dynamic pattern of laminin α chain expression in the BLs of the developing nephron. To document these results, it is first necessary to summarize the main stages of nephrogenesis (Fig. 7).

Bottom Line: Interspecific backcross mapping of the five alpha chain genes revealed that they are distributed on four mouse chromosomes.Finally, we identified a novel full-length alpha3 isoform encoded by the Lama3 gene, which was previously believed to encode only truncated chains.Together, these results reveal remarkable diversity in BL composition and complexity in BL development.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.

ABSTRACT
Laminin trimers composed of alpha, beta, and gamma chains are major components of basal laminae (BLs) throughout the body. To date, three alpha chains (alpha1-3) have been shown to assemble into at least seven heterotrimers (called laminins 1-7). Genes encoding two additional alpha chains (alpha4 and alpha5) have been cloned, but little is known about their expression, and their protein products have not been identified. Here we generated antisera to recombinant alpha4 and alpha5 and used them to identify authentic proteins in tissue extracts. Immunoprecipitation and immunoblotting showed that alpha4 and alpha5 assemble into four novel laminin heterotrimers (laminins 8-11: alpha4beta1gamma1, alpha4beta2gamma1, alpha5beta1gamma1, and alpha5beta2gamma1, respectively). Using a panel of nucleotide and antibody probes, we surveyed the expression of alpha1-5 in murine tissues. All five chains were expressed in both embryos and adults, but each was distributed in a distinct pattern at both RNA and protein levels. Overall, alpha4 and alpha5 exhibited the broadest patterns of expression, while expression of alpha1 was the most restricted. Immunohistochemical analysis of kidney, lung, and heart showed that the alpha chains were confined to extracellular matrix and, with few exceptions, to BLs. All developing and adult BLs examined contained at least one alpha chain, all alpha chains were present in multiple BLs, and some BLs contained two or three alpha chains. Detailed analysis of developing kidney revealed that some individual BLs, including those of the tubule and glomerulus, changed in laminin chain composition as they matured, expressing up to three different alpha chains and two different beta chains in an elaborate and dynamic progression. Interspecific backcross mapping of the five alpha chain genes revealed that they are distributed on four mouse chromosomes. Finally, we identified a novel full-length alpha3 isoform encoded by the Lama3 gene, which was previously believed to encode only truncated chains. Together, these results reveal remarkable diversity in BL composition and complexity in BL development.

Show MeSH
Related in: MedlinePlus