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DPY-17 and MUA-3 Interact for Connective Tissue-Like Tissue Integrity in Caenorhabditis elegans: A Model for Marfan Syndrome.

Fotopoulos P, Kim J, Hyun M, Qamari W, Lee I, You YJ - G3 (Bethesda) (2015)

Bottom Line: RNAi of dpy-17 in mua-3 rescued the lethality, confirming dpy-17 is a suppressor. dpy-17 encodes a collagen known to genetically interact with dpy-31, a BMP-1/Tolloid-like metalloprotease required for TGFβ activation in mammals.Consistent with that, RNAi of dbl-1, a TGFβ homolog, modestly rescued the lethality of mua-3 mutants, suggesting a potentially conserved interaction between MUA-3 and a TGFβ pathway in C. elegans.Our work provides genetic evidence of the interaction between TGFβ and a fibrillin homolog, and thus provides a simple yet powerful genetic model to study TGFβ function in development of Marfan pathology.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298.

No MeSH data available.


Related in: MedlinePlus

dbl-1 genetically interacts with mua-3 mutants. (A) RNAi of TGFβ2 homolog (dbl-1) rescued the mua-3 lethality at 25°. The numbers are average percent survival ± SEM. (B) A mutation in dbl-1 did not rescue the mua-3 lethality at 25°. (C) A mutation in dbl-1 reduces the survival of mua-3 at 15°.
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fig3: dbl-1 genetically interacts with mua-3 mutants. (A) RNAi of TGFβ2 homolog (dbl-1) rescued the mua-3 lethality at 25°. The numbers are average percent survival ± SEM. (B) A mutation in dbl-1 did not rescue the mua-3 lethality at 25°. (C) A mutation in dbl-1 reduces the survival of mua-3 at 15°.

Mentions: Because the sequence of mua-3 is most similar to the human fibrillin1 gene, and because the phenotype of our new mutant mimics certain aspects of Marfan pathology, we investigated the potential genetic interaction between mua-3 and TGFβ2 signaling. Recent studies show that overactivation of the TGFβ2 pathway results in Marfan pathology and appearances such as connective tissue defects and long stature (for review see Lindsay and Dietz 2011). Interestingly, overexpressing DBL-1, a homolog of TGFβ2, increases body size in C. elegans (Morita et al. 2002). We hypothesized that the DBL-1 TGFβ pathway regulates body size in C. elegans as TGFβ2 does in humans, and thus in the mua-3 mutants increased TGFβ signaling may contribute to lethality. To test this hypothesis, we knocked down the expression of dbl-1 by RNAi and examined whether mua-3 lethality was reduced. RNAi reduced the lethality of mua-3 mildly yet significantly, suggesting a potential conserved link between excess TGFβ signaling and misregulation in body size shown in Marfan syndrome in C. elegans (Figure 3A). We generated double mutants of mua-3; dbl-1 to further examine the interaction between two genes. The existing allele of dbl-1(nk3) carries a deletion covering the entire gene, and thus no protein is made. The double mutants did not survive any better than mua-3 single mutants at 25° (Figure 3B). Interestingly, however, the double mutants die more at 15°, clearly showing a genetic interaction between two genes (Figure 3C). That the mutation of dbl-1 cannot rescue mua-3 but RNAi knockdown of dbl-1 can suggest that complete knockout of dbl-1 does not help mua-3, but reduction of MUA-3 levels does. Also, the increase of the death in the double mutants shows there is genetic interaction between these two. This is fully consistent with the findings in mammals. Reduction of TGFβ2 by various means alleviates Marfan syndrome. However, conditional yet complete knockout TGFβ2 receptor in smooth muscle cells impairs the contractile apparatus of vascular smooth muscle and exacerbates the aortic disease induced by mutation of fibrillin1 (Li et al. 2014).


DPY-17 and MUA-3 Interact for Connective Tissue-Like Tissue Integrity in Caenorhabditis elegans: A Model for Marfan Syndrome.

Fotopoulos P, Kim J, Hyun M, Qamari W, Lee I, You YJ - G3 (Bethesda) (2015)

dbl-1 genetically interacts with mua-3 mutants. (A) RNAi of TGFβ2 homolog (dbl-1) rescued the mua-3 lethality at 25°. The numbers are average percent survival ± SEM. (B) A mutation in dbl-1 did not rescue the mua-3 lethality at 25°. (C) A mutation in dbl-1 reduces the survival of mua-3 at 15°.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4502371&req=5

fig3: dbl-1 genetically interacts with mua-3 mutants. (A) RNAi of TGFβ2 homolog (dbl-1) rescued the mua-3 lethality at 25°. The numbers are average percent survival ± SEM. (B) A mutation in dbl-1 did not rescue the mua-3 lethality at 25°. (C) A mutation in dbl-1 reduces the survival of mua-3 at 15°.
Mentions: Because the sequence of mua-3 is most similar to the human fibrillin1 gene, and because the phenotype of our new mutant mimics certain aspects of Marfan pathology, we investigated the potential genetic interaction between mua-3 and TGFβ2 signaling. Recent studies show that overactivation of the TGFβ2 pathway results in Marfan pathology and appearances such as connective tissue defects and long stature (for review see Lindsay and Dietz 2011). Interestingly, overexpressing DBL-1, a homolog of TGFβ2, increases body size in C. elegans (Morita et al. 2002). We hypothesized that the DBL-1 TGFβ pathway regulates body size in C. elegans as TGFβ2 does in humans, and thus in the mua-3 mutants increased TGFβ signaling may contribute to lethality. To test this hypothesis, we knocked down the expression of dbl-1 by RNAi and examined whether mua-3 lethality was reduced. RNAi reduced the lethality of mua-3 mildly yet significantly, suggesting a potential conserved link between excess TGFβ signaling and misregulation in body size shown in Marfan syndrome in C. elegans (Figure 3A). We generated double mutants of mua-3; dbl-1 to further examine the interaction between two genes. The existing allele of dbl-1(nk3) carries a deletion covering the entire gene, and thus no protein is made. The double mutants did not survive any better than mua-3 single mutants at 25° (Figure 3B). Interestingly, however, the double mutants die more at 15°, clearly showing a genetic interaction between two genes (Figure 3C). That the mutation of dbl-1 cannot rescue mua-3 but RNAi knockdown of dbl-1 can suggest that complete knockout of dbl-1 does not help mua-3, but reduction of MUA-3 levels does. Also, the increase of the death in the double mutants shows there is genetic interaction between these two. This is fully consistent with the findings in mammals. Reduction of TGFβ2 by various means alleviates Marfan syndrome. However, conditional yet complete knockout TGFβ2 receptor in smooth muscle cells impairs the contractile apparatus of vascular smooth muscle and exacerbates the aortic disease induced by mutation of fibrillin1 (Li et al. 2014).

Bottom Line: RNAi of dpy-17 in mua-3 rescued the lethality, confirming dpy-17 is a suppressor. dpy-17 encodes a collagen known to genetically interact with dpy-31, a BMP-1/Tolloid-like metalloprotease required for TGFβ activation in mammals.Consistent with that, RNAi of dbl-1, a TGFβ homolog, modestly rescued the lethality of mua-3 mutants, suggesting a potentially conserved interaction between MUA-3 and a TGFβ pathway in C. elegans.Our work provides genetic evidence of the interaction between TGFβ and a fibrillin homolog, and thus provides a simple yet powerful genetic model to study TGFβ function in development of Marfan pathology.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298.

No MeSH data available.


Related in: MedlinePlus