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alpha3beta1 Integrin is required for normal development of the epidermal basement membrane.

DiPersio CM, Hodivala-Dilke KM, Jaenisch R, Kreidberg JA, Hynes RO - J. Cell Biol. (1997)

Bottom Line: Laminin-5 and other matrix proteins remained associated with both the dermal and epidermal sides of blisters, suggesting rupture of the basement membrane itself, rather than detachment of the epidermis from the basement membrane as occurs in some blistering disorders such as epidermolysis bullosa.Consistent with this notion, primary keratinocytes from alpha3beta1-deficient skin adhered to laminin-5 through alpha6 integrins.However, alpha3beta1-deficient keratinocytes spread poorly compared with wild-type cells on laminin-5, demonstrating a postattachment requirement for alpha3beta1 and indicating distinct roles for alpha3beta1 and alpha6beta4.

View Article: PubMed Central - PubMed

Affiliation: Center for Cancer Research, and Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.

ABSTRACT
Integrins alpha3beta1 and alpha6beta4 are abundant receptors on keratinocytes for laminin-5, a major component of the basement membrane between the epidermis and the dermis in skin. These integrins are recruited to distinct adhesion structures within keratinocytes; alpha6beta4 is present in hemidesmosomes, while alpha3beta1 is recruited into focal contacts in cultured cells. To determine whether differences in localization reflect distinct functions of these integrins in the epidermis, we studied skin development in alpha3beta1-deficient mice. Examination of extracellular matrix by immunofluorescence microscopy and electron microscopy revealed regions of disorganized basement membrane in alpha3beta1-deficient skin. Disorganized matrix was first detected by day 15.5 of embryonic development and became progressively more extensive as development proceeded. In neonatal skin, matrix disorganization was frequently accompanied by blistering at the dermal-epidermal junction. Laminin-5 and other matrix proteins remained associated with both the dermal and epidermal sides of blisters, suggesting rupture of the basement membrane itself, rather than detachment of the epidermis from the basement membrane as occurs in some blistering disorders such as epidermolysis bullosa. Consistent with this notion, primary keratinocytes from alpha3beta1-deficient skin adhered to laminin-5 through alpha6 integrins. However, alpha3beta1-deficient keratinocytes spread poorly compared with wild-type cells on laminin-5, demonstrating a postattachment requirement for alpha3beta1 and indicating distinct roles for alpha3beta1 and alpha6beta4. Our findings support a novel role for alpha3beta1 in establishment and/or maintenance of basement membrane integrity, while alpha6beta4 is required for stable adhesion of the epidermis to the basement membrane through hemidesmosomes.

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The basement membrane in α3-  skin is disorganized. (A–D) Frozen skin sections from wild-type (A and C) or α3- (B  and D) mice were viewed by phase contrast  (A and B) or stained by immunofluorescence  with an antiserum against laminin-5 (C and  D). Arrowheads point to areas of laminin-5  staining at the basement membrane in the  wild-type skin (A and C) or at regions of disorganized basement membrane in α3-  skin (B and D). (E and F) Electron micrographs comparing ultrastructure of the basement membrane zone in wild-type (E) and  α3- (F) skin. (G and H) Schematic illustration of relevant structures seen in E and F.  BK, basal keratinocyte; LL, lamina lucida;  LD, lamina densa; arrowheads point to  hemidesmosomes along the basal aspect of  the plasma membranes in the basal keratinocytes. Bars: (D) 50 μm; (F) 200 nm.
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Figure 3: The basement membrane in α3- skin is disorganized. (A–D) Frozen skin sections from wild-type (A and C) or α3- (B and D) mice were viewed by phase contrast (A and B) or stained by immunofluorescence with an antiserum against laminin-5 (C and D). Arrowheads point to areas of laminin-5 staining at the basement membrane in the wild-type skin (A and C) or at regions of disorganized basement membrane in α3- skin (B and D). (E and F) Electron micrographs comparing ultrastructure of the basement membrane zone in wild-type (E) and α3- (F) skin. (G and H) Schematic illustration of relevant structures seen in E and F. BK, basal keratinocyte; LL, lamina lucida; LD, lamina densa; arrowheads point to hemidesmosomes along the basal aspect of the plasma membranes in the basal keratinocytes. Bars: (D) 50 μm; (F) 200 nm.

Mentions: Given the rupture of the basement membrane in blistered regions of α3- skin, we also examined basement membrane organization in nonblistered regions. As expected, laminin-5 in wild-type skin was restricted to the basement membrane directly below the basal keratinocytes of the epidermis (Fig. 3, A and C, arrowheads); the basement membrane appeared intact throughout each section examined. In marked contrast, staining of skin from α3- mice revealed extensive regions of matrix disorganization, where laminin-5 was also detected below the plane of the basement membrane (Fig. 3 D, arrowheads). Phase contrast of the same field showed that the epidermis and dermis were intact through these regions (Fig. 3 B). In some cases, dense concentrations of laminin-5, resembling continuous remnants of basement membrane, extended down into the dermal regions (for example, see Fig. 4 F). Laminin-5 staining of the basement membrane appeared normal in mice heterozygous for the α3- mutation, where α3β1 levels were reduced but still easily detectable (not shown). Based on the disorganized matrix/blistering phenotype, we were routinely able to identify skin sections from α3- mice before confirmation of genotype by PCR or Southern blot analysis.


alpha3beta1 Integrin is required for normal development of the epidermal basement membrane.

DiPersio CM, Hodivala-Dilke KM, Jaenisch R, Kreidberg JA, Hynes RO - J. Cell Biol. (1997)

The basement membrane in α3-  skin is disorganized. (A–D) Frozen skin sections from wild-type (A and C) or α3- (B  and D) mice were viewed by phase contrast  (A and B) or stained by immunofluorescence  with an antiserum against laminin-5 (C and  D). Arrowheads point to areas of laminin-5  staining at the basement membrane in the  wild-type skin (A and C) or at regions of disorganized basement membrane in α3-  skin (B and D). (E and F) Electron micrographs comparing ultrastructure of the basement membrane zone in wild-type (E) and  α3- (F) skin. (G and H) Schematic illustration of relevant structures seen in E and F.  BK, basal keratinocyte; LL, lamina lucida;  LD, lamina densa; arrowheads point to  hemidesmosomes along the basal aspect of  the plasma membranes in the basal keratinocytes. Bars: (D) 50 μm; (F) 200 nm.
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Figure 3: The basement membrane in α3- skin is disorganized. (A–D) Frozen skin sections from wild-type (A and C) or α3- (B and D) mice were viewed by phase contrast (A and B) or stained by immunofluorescence with an antiserum against laminin-5 (C and D). Arrowheads point to areas of laminin-5 staining at the basement membrane in the wild-type skin (A and C) or at regions of disorganized basement membrane in α3- skin (B and D). (E and F) Electron micrographs comparing ultrastructure of the basement membrane zone in wild-type (E) and α3- (F) skin. (G and H) Schematic illustration of relevant structures seen in E and F. BK, basal keratinocyte; LL, lamina lucida; LD, lamina densa; arrowheads point to hemidesmosomes along the basal aspect of the plasma membranes in the basal keratinocytes. Bars: (D) 50 μm; (F) 200 nm.
Mentions: Given the rupture of the basement membrane in blistered regions of α3- skin, we also examined basement membrane organization in nonblistered regions. As expected, laminin-5 in wild-type skin was restricted to the basement membrane directly below the basal keratinocytes of the epidermis (Fig. 3, A and C, arrowheads); the basement membrane appeared intact throughout each section examined. In marked contrast, staining of skin from α3- mice revealed extensive regions of matrix disorganization, where laminin-5 was also detected below the plane of the basement membrane (Fig. 3 D, arrowheads). Phase contrast of the same field showed that the epidermis and dermis were intact through these regions (Fig. 3 B). In some cases, dense concentrations of laminin-5, resembling continuous remnants of basement membrane, extended down into the dermal regions (for example, see Fig. 4 F). Laminin-5 staining of the basement membrane appeared normal in mice heterozygous for the α3- mutation, where α3β1 levels were reduced but still easily detectable (not shown). Based on the disorganized matrix/blistering phenotype, we were routinely able to identify skin sections from α3- mice before confirmation of genotype by PCR or Southern blot analysis.

Bottom Line: Laminin-5 and other matrix proteins remained associated with both the dermal and epidermal sides of blisters, suggesting rupture of the basement membrane itself, rather than detachment of the epidermis from the basement membrane as occurs in some blistering disorders such as epidermolysis bullosa.Consistent with this notion, primary keratinocytes from alpha3beta1-deficient skin adhered to laminin-5 through alpha6 integrins.However, alpha3beta1-deficient keratinocytes spread poorly compared with wild-type cells on laminin-5, demonstrating a postattachment requirement for alpha3beta1 and indicating distinct roles for alpha3beta1 and alpha6beta4.

View Article: PubMed Central - PubMed

Affiliation: Center for Cancer Research, and Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.

ABSTRACT
Integrins alpha3beta1 and alpha6beta4 are abundant receptors on keratinocytes for laminin-5, a major component of the basement membrane between the epidermis and the dermis in skin. These integrins are recruited to distinct adhesion structures within keratinocytes; alpha6beta4 is present in hemidesmosomes, while alpha3beta1 is recruited into focal contacts in cultured cells. To determine whether differences in localization reflect distinct functions of these integrins in the epidermis, we studied skin development in alpha3beta1-deficient mice. Examination of extracellular matrix by immunofluorescence microscopy and electron microscopy revealed regions of disorganized basement membrane in alpha3beta1-deficient skin. Disorganized matrix was first detected by day 15.5 of embryonic development and became progressively more extensive as development proceeded. In neonatal skin, matrix disorganization was frequently accompanied by blistering at the dermal-epidermal junction. Laminin-5 and other matrix proteins remained associated with both the dermal and epidermal sides of blisters, suggesting rupture of the basement membrane itself, rather than detachment of the epidermis from the basement membrane as occurs in some blistering disorders such as epidermolysis bullosa. Consistent with this notion, primary keratinocytes from alpha3beta1-deficient skin adhered to laminin-5 through alpha6 integrins. However, alpha3beta1-deficient keratinocytes spread poorly compared with wild-type cells on laminin-5, demonstrating a postattachment requirement for alpha3beta1 and indicating distinct roles for alpha3beta1 and alpha6beta4. Our findings support a novel role for alpha3beta1 in establishment and/or maintenance of basement membrane integrity, while alpha6beta4 is required for stable adhesion of the epidermis to the basement membrane through hemidesmosomes.

Show MeSH
Related in: MedlinePlus