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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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In situ hybridization of laminin α chain probes to E15.5 embryo parasagittal sections. (a) α1, (b) α2, (c) α3, (d) α4, and (e) α5.  α1 shows restricted expression in kidney and meninges (arrowheads); α2 and α4 show widespread expression in mesenchymal cells and  derivatives as well as in dorsal root ganglia (arrowheads); and α3 and α5 transcripts localize primarily to epithelia. (f–h) High power  views of (f) α3, (g) α4, and (h) α5 expression in lung. α3 and α5 are concentrated in the epithelial lung buds, and α4 to the mesenchyme.  H, heart; K, kidney; L, lung; SG, salivary gland; T, tongue (muscle). Bars: (d) 1 mm; (h) 50 μm.
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Figure 4: In situ hybridization of laminin α chain probes to E15.5 embryo parasagittal sections. (a) α1, (b) α2, (c) α3, (d) α4, and (e) α5. α1 shows restricted expression in kidney and meninges (arrowheads); α2 and α4 show widespread expression in mesenchymal cells and derivatives as well as in dorsal root ganglia (arrowheads); and α3 and α5 transcripts localize primarily to epithelia. (f–h) High power views of (f) α3, (g) α4, and (h) α5 expression in lung. α3 and α5 are concentrated in the epithelial lung buds, and α4 to the mesenchyme. H, heart; K, kidney; L, lung; SG, salivary gland; T, tongue (muscle). Bars: (d) 1 mm; (h) 50 μm.

Mentions: To map α chain expression in younger embryos (E15.5), we used in situ hybridization. Laminin α1 was detected in the kidney and in the meninges of the central nervous system (Fig. 4 a). Laminin α2 was observed primarily in the developing skeletal musculature, in dorsal root ganglia, and in kidney (Fig. 4 b). Laminin α3A/B was strongly expressed in skin, lung, olfactory epithelium, and the superficial layers of the tongue and palate (Fig. 4 c). Laminin α4 was expressed strongly in mesenchymal tissues of the head, in dorsal root ganglia, and in intestine, and was observed diffusely in skeletal and cardiac muscle (Fig. 4 d). Finally, laminin α5 was expressed in a pattern similar to α3, with additional sites of expression in salivary gland, in intestine, and in the most superficial cells of the liver (Fig. 4 e).


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)

In situ hybridization of laminin α chain probes to E15.5 embryo parasagittal sections. (a) α1, (b) α2, (c) α3, (d) α4, and (e) α5.  α1 shows restricted expression in kidney and meninges (arrowheads); α2 and α4 show widespread expression in mesenchymal cells and  derivatives as well as in dorsal root ganglia (arrowheads); and α3 and α5 transcripts localize primarily to epithelia. (f–h) High power  views of (f) α3, (g) α4, and (h) α5 expression in lung. α3 and α5 are concentrated in the epithelial lung buds, and α4 to the mesenchyme.  H, heart; K, kidney; L, lung; SG, salivary gland; T, tongue (muscle). Bars: (d) 1 mm; (h) 50 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2139892&req=5

Figure 4: In situ hybridization of laminin α chain probes to E15.5 embryo parasagittal sections. (a) α1, (b) α2, (c) α3, (d) α4, and (e) α5. α1 shows restricted expression in kidney and meninges (arrowheads); α2 and α4 show widespread expression in mesenchymal cells and derivatives as well as in dorsal root ganglia (arrowheads); and α3 and α5 transcripts localize primarily to epithelia. (f–h) High power views of (f) α3, (g) α4, and (h) α5 expression in lung. α3 and α5 are concentrated in the epithelial lung buds, and α4 to the mesenchyme. H, heart; K, kidney; L, lung; SG, salivary gland; T, tongue (muscle). Bars: (d) 1 mm; (h) 50 μm.
Mentions: To map α chain expression in younger embryos (E15.5), we used in situ hybridization. Laminin α1 was detected in the kidney and in the meninges of the central nervous system (Fig. 4 a). Laminin α2 was observed primarily in the developing skeletal musculature, in dorsal root ganglia, and in kidney (Fig. 4 b). Laminin α3A/B was strongly expressed in skin, lung, olfactory epithelium, and the superficial layers of the tongue and palate (Fig. 4 c). Laminin α4 was expressed strongly in mesenchymal tissues of the head, in dorsal root ganglia, and in intestine, and was observed diffusely in skeletal and cardiac muscle (Fig. 4 d). Finally, laminin α5 was expressed in a pattern similar to α3, with additional sites of expression in salivary gland, in intestine, and in the most superficial cells of the liver (Fig. 4 e).

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