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Site-specific inductive and inhibitory activities of MMP-2 and MMP-3 orchestrate mammary gland branching morphogenesis.

Wiseman BS, Sternlicht MD, Lund LR, Alexander CM, Mott J, Bissell MJ, Soloway P, Itohara S, Werb Z - J. Cell Biol. (2003)

Bottom Line: Unexpectedly, MMP-2 also represses precocious lateral branching during mid-puberty.In contrast, MMP-3 induces secondary and tertiary lateral branching of ducts during mid-puberty and early pregnancy.Thus, specific MMPs refine the mammary branching pattern by distinct mechanisms during mammary gland branching morphogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, University of California, San Francisco, CA 94143-0452, USA.

ABSTRACT
During puberty, mouse mammary epithelial ducts invade the stromal mammary fat pad in a wave of branching morphogenesis to form a complex ductal tree. Using pharmacologic and genetic approaches, we find that mammary gland branching morphogenesis requires transient matrix metalloproteinase (MMP) activity for invasion and branch point selection. MMP-2, but not MMP-9, facilitates terminal end bud invasion by inhibiting epithelial cell apoptosis at the start of puberty. Unexpectedly, MMP-2 also represses precocious lateral branching during mid-puberty. In contrast, MMP-3 induces secondary and tertiary lateral branching of ducts during mid-puberty and early pregnancy. Nevertheless, the mammary gland is able to develop lactational competence in MMP mutant mice. Thus, specific MMPs refine the mammary branching pattern by distinct mechanisms during mammary gland branching morphogenesis.

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MMP-3 is required for lateral branching in the mammary gland. (A–H) Whole mounts of mammary glands of (A, C, E, and G) MMP-3 +/− and (B, D, F, and H) MMP-3 −/− mice at (A and B) 42 d old in estrus, (C and D) 6 d of pregnancy, (E and F) 9 d of pregnancy, and (G and H) 13 d of pregnancy. (I and J) Whole mounts of mammary glands of 70-d-old virgin (I) nontransgenic controls or (J) WAP-MMP-3 transgenic mice. Bars, 1 mm. (K) Wild-type mammary gland stained for Ln-1. Note reduction in Ln-1 where lateral branches are budding (arrows). Bar, 25 μm. (L–N) Penetration of ducts (L), number of total branches per millimeter (M), and number of ramified secondary branches per millimeter (N) from primary ducts of MMP-3 −/− and MMP-3 +/− mammary glands. Data are mean ± SEM using 4–12 mammary glands per data point. ***, P < 0.0005; **, P < 0.005; *P, < 0.05, unpaired, two-tailed t test.
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fig5: MMP-3 is required for lateral branching in the mammary gland. (A–H) Whole mounts of mammary glands of (A, C, E, and G) MMP-3 +/− and (B, D, F, and H) MMP-3 −/− mice at (A and B) 42 d old in estrus, (C and D) 6 d of pregnancy, (E and F) 9 d of pregnancy, and (G and H) 13 d of pregnancy. (I and J) Whole mounts of mammary glands of 70-d-old virgin (I) nontransgenic controls or (J) WAP-MMP-3 transgenic mice. Bars, 1 mm. (K) Wild-type mammary gland stained for Ln-1. Note reduction in Ln-1 where lateral branches are budding (arrows). Bar, 25 μm. (L–N) Penetration of ducts (L), number of total branches per millimeter (M), and number of ramified secondary branches per millimeter (N) from primary ducts of MMP-3 −/− and MMP-3 +/− mammary glands. Data are mean ± SEM using 4–12 mammary glands per data point. ***, P < 0.0005; **, P < 0.005; *P, < 0.05, unpaired, two-tailed t test.

Mentions: MMP-3 −/− mice showed a loss of function phenotype (Fig. 5, A and B) that was the mirror image of the gain of function phenotype that we described previously in WAP-MMP-3 transgenic mice (Fig. 5, I and J; Sympson et al., 1994). The heterozygote and wild-type mice were indistinguishable. In contrast to MMP-2 −/− mice, the ductal tree of mammary glands from MMP-3 −/− mice was much sparser, yet there were no differences in primary ductal invasion compared with controls (Fig. 5, A, B, and L). Both the frequency of branches and the total number of branch points were greatly reduced in MMP-3 −/− mice (Fig. 5 M and not depicted). However, there was no difference in the number of TEBs (not depicted) between MMP-3 −/− glands and controls, indicating that MMP-3 was needed for lateral branching, rather than dichotomous branching through TEB bifurcation. Furthermore, ramified secondary branches were absent (Fig. 5 N), implying that MMP-3 regulates both secondary and tertiary branching. This phenotype was transient and most evident around 50 d old (Fig. 5, M and N). By 70 d old, the mammary ductal tree in MMP-3 −/− mice was indistinguishable from controls, indicating that other factors can compensate for MMPs after 50 d.


Site-specific inductive and inhibitory activities of MMP-2 and MMP-3 orchestrate mammary gland branching morphogenesis.

Wiseman BS, Sternlicht MD, Lund LR, Alexander CM, Mott J, Bissell MJ, Soloway P, Itohara S, Werb Z - J. Cell Biol. (2003)

MMP-3 is required for lateral branching in the mammary gland. (A–H) Whole mounts of mammary glands of (A, C, E, and G) MMP-3 +/− and (B, D, F, and H) MMP-3 −/− mice at (A and B) 42 d old in estrus, (C and D) 6 d of pregnancy, (E and F) 9 d of pregnancy, and (G and H) 13 d of pregnancy. (I and J) Whole mounts of mammary glands of 70-d-old virgin (I) nontransgenic controls or (J) WAP-MMP-3 transgenic mice. Bars, 1 mm. (K) Wild-type mammary gland stained for Ln-1. Note reduction in Ln-1 where lateral branches are budding (arrows). Bar, 25 μm. (L–N) Penetration of ducts (L), number of total branches per millimeter (M), and number of ramified secondary branches per millimeter (N) from primary ducts of MMP-3 −/− and MMP-3 +/− mammary glands. Data are mean ± SEM using 4–12 mammary glands per data point. ***, P < 0.0005; **, P < 0.005; *P, < 0.05, unpaired, two-tailed t test.
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Related In: Results  -  Collection

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fig5: MMP-3 is required for lateral branching in the mammary gland. (A–H) Whole mounts of mammary glands of (A, C, E, and G) MMP-3 +/− and (B, D, F, and H) MMP-3 −/− mice at (A and B) 42 d old in estrus, (C and D) 6 d of pregnancy, (E and F) 9 d of pregnancy, and (G and H) 13 d of pregnancy. (I and J) Whole mounts of mammary glands of 70-d-old virgin (I) nontransgenic controls or (J) WAP-MMP-3 transgenic mice. Bars, 1 mm. (K) Wild-type mammary gland stained for Ln-1. Note reduction in Ln-1 where lateral branches are budding (arrows). Bar, 25 μm. (L–N) Penetration of ducts (L), number of total branches per millimeter (M), and number of ramified secondary branches per millimeter (N) from primary ducts of MMP-3 −/− and MMP-3 +/− mammary glands. Data are mean ± SEM using 4–12 mammary glands per data point. ***, P < 0.0005; **, P < 0.005; *P, < 0.05, unpaired, two-tailed t test.
Mentions: MMP-3 −/− mice showed a loss of function phenotype (Fig. 5, A and B) that was the mirror image of the gain of function phenotype that we described previously in WAP-MMP-3 transgenic mice (Fig. 5, I and J; Sympson et al., 1994). The heterozygote and wild-type mice were indistinguishable. In contrast to MMP-2 −/− mice, the ductal tree of mammary glands from MMP-3 −/− mice was much sparser, yet there were no differences in primary ductal invasion compared with controls (Fig. 5, A, B, and L). Both the frequency of branches and the total number of branch points were greatly reduced in MMP-3 −/− mice (Fig. 5 M and not depicted). However, there was no difference in the number of TEBs (not depicted) between MMP-3 −/− glands and controls, indicating that MMP-3 was needed for lateral branching, rather than dichotomous branching through TEB bifurcation. Furthermore, ramified secondary branches were absent (Fig. 5 N), implying that MMP-3 regulates both secondary and tertiary branching. This phenotype was transient and most evident around 50 d old (Fig. 5, M and N). By 70 d old, the mammary ductal tree in MMP-3 −/− mice was indistinguishable from controls, indicating that other factors can compensate for MMPs after 50 d.

Bottom Line: Unexpectedly, MMP-2 also represses precocious lateral branching during mid-puberty.In contrast, MMP-3 induces secondary and tertiary lateral branching of ducts during mid-puberty and early pregnancy.Thus, specific MMPs refine the mammary branching pattern by distinct mechanisms during mammary gland branching morphogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, University of California, San Francisco, CA 94143-0452, USA.

ABSTRACT
During puberty, mouse mammary epithelial ducts invade the stromal mammary fat pad in a wave of branching morphogenesis to form a complex ductal tree. Using pharmacologic and genetic approaches, we find that mammary gland branching morphogenesis requires transient matrix metalloproteinase (MMP) activity for invasion and branch point selection. MMP-2, but not MMP-9, facilitates terminal end bud invasion by inhibiting epithelial cell apoptosis at the start of puberty. Unexpectedly, MMP-2 also represses precocious lateral branching during mid-puberty. In contrast, MMP-3 induces secondary and tertiary lateral branching of ducts during mid-puberty and early pregnancy. Nevertheless, the mammary gland is able to develop lactational competence in MMP mutant mice. Thus, specific MMPs refine the mammary branching pattern by distinct mechanisms during mammary gland branching morphogenesis.

Show MeSH
Related in: MedlinePlus