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Ablation of Cypher, a PDZ-LIM domain Z-line protein, causes a severe form of congenital myopathy.

Zhou Q, Chu PH, Huang C, Cheng CF, Martone ME, Knoll G, Shelton GD, Evans S, Chen J - J. Cell Biol. (2001)

Bottom Line: Examination of striated muscle from the mutants revealed that Cypher is not required for sarcomerogenesis or Z-line assembly, but rather is required for maintenance of the Z-line during muscle function.In vitro studies demonstrated that individual domains within Cypher localize independently to the Z-line via interactions with alpha-actinin or other Z-line components.These results suggest that Cypher functions as a linker-strut to maintain cytoskeletal structure during contraction.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Medicine and Department of Medicine, University of California at San Diego School of Medicine, La Jolla, CA 92093, USA.

ABSTRACT
Cypher is a member of a recently emerging family of proteins containing a PDZ domain at their NH(2) terminus and one or three LIM domains at their COOH terminus. Cypher knockout mice display a severe form of congenital myopathy and die postnatally from functional failure in multiple striated muscles. Examination of striated muscle from the mutants revealed that Cypher is not required for sarcomerogenesis or Z-line assembly, but rather is required for maintenance of the Z-line during muscle function. In vitro studies demonstrated that individual domains within Cypher localize independently to the Z-line via interactions with alpha-actinin or other Z-line components. These results suggest that Cypher functions as a linker-strut to maintain cytoskeletal structure during contraction.

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X-gal staining of cypher LacZ/knock-in heterozygous embryos at different development stages. Embryos from embryonic day (E) 8.5, 9.5, 11.5, and 13.5 were stained with X-gal for ∼8 h at 30°C. X-gal staining of heart (H) was detected from E 8.5. Somite (S) staining was not detectable at E 8.5, but was detected at E 9.5 in a decreasing rostral to caudal gradient. The somite expression pattern progresses caudally through E 11.5, corresponding to somite maturation. At this stage, cypher expression was also detected in cells migrating from the myotome (M). At E 13.5, cypher expression was detected throughout the embryonic musculature. Bar, 1 mm.
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fig2: X-gal staining of cypher LacZ/knock-in heterozygous embryos at different development stages. Embryos from embryonic day (E) 8.5, 9.5, 11.5, and 13.5 were stained with X-gal for ∼8 h at 30°C. X-gal staining of heart (H) was detected from E 8.5. Somite (S) staining was not detectable at E 8.5, but was detected at E 9.5 in a decreasing rostral to caudal gradient. The somite expression pattern progresses caudally through E 11.5, corresponding to somite maturation. At this stage, cypher expression was also detected in cells migrating from the myotome (M). At E 13.5, cypher expression was detected throughout the embryonic musculature. Bar, 1 mm.

Mentions: To understand the in vivo function of Cypher in striated muscle and to exploit cypher as a potentially useful lineage marker, we used homologous recombination to knock-in a β-galactosidase cDNA downstream of the endogenous cypher promoter, meanwhile disrupting the cypher gene which encodes both Cypher1 and Cypher2 (Fig. 1). Assays for β-galactosidase activity are very sensitive and give resolution at the single cell level, thus permitting us to look in greater detail at expression of cypher during embryogenesis (Chu et al., 2000). As shown in Fig. 2, cypher is expressed exclusively in heart at embryonic day (E) 8.5, but at E 9.5 it was detected in somites in a rostral to caudal gradient, with highest expression rostrally. The somite expression pattern progresses caudally through E 11.5, corresponding to somite maturation. At this stage, cypher expression was also detected in cells migrating from the myotome. At E 13.5, cypher expression was detected throughout the embryonic musculature. The X-gal staining pattern observed here matches well with our previous RNA in situ hybridization results, with the exception that the X-gal staining was observed earlier in the somites, in keeping with its greater sensitivity (Zhou et al., 1999).


Ablation of Cypher, a PDZ-LIM domain Z-line protein, causes a severe form of congenital myopathy.

Zhou Q, Chu PH, Huang C, Cheng CF, Martone ME, Knoll G, Shelton GD, Evans S, Chen J - J. Cell Biol. (2001)

X-gal staining of cypher LacZ/knock-in heterozygous embryos at different development stages. Embryos from embryonic day (E) 8.5, 9.5, 11.5, and 13.5 were stained with X-gal for ∼8 h at 30°C. X-gal staining of heart (H) was detected from E 8.5. Somite (S) staining was not detectable at E 8.5, but was detected at E 9.5 in a decreasing rostral to caudal gradient. The somite expression pattern progresses caudally through E 11.5, corresponding to somite maturation. At this stage, cypher expression was also detected in cells migrating from the myotome (M). At E 13.5, cypher expression was detected throughout the embryonic musculature. Bar, 1 mm.
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Related In: Results  -  Collection

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fig2: X-gal staining of cypher LacZ/knock-in heterozygous embryos at different development stages. Embryos from embryonic day (E) 8.5, 9.5, 11.5, and 13.5 were stained with X-gal for ∼8 h at 30°C. X-gal staining of heart (H) was detected from E 8.5. Somite (S) staining was not detectable at E 8.5, but was detected at E 9.5 in a decreasing rostral to caudal gradient. The somite expression pattern progresses caudally through E 11.5, corresponding to somite maturation. At this stage, cypher expression was also detected in cells migrating from the myotome (M). At E 13.5, cypher expression was detected throughout the embryonic musculature. Bar, 1 mm.
Mentions: To understand the in vivo function of Cypher in striated muscle and to exploit cypher as a potentially useful lineage marker, we used homologous recombination to knock-in a β-galactosidase cDNA downstream of the endogenous cypher promoter, meanwhile disrupting the cypher gene which encodes both Cypher1 and Cypher2 (Fig. 1). Assays for β-galactosidase activity are very sensitive and give resolution at the single cell level, thus permitting us to look in greater detail at expression of cypher during embryogenesis (Chu et al., 2000). As shown in Fig. 2, cypher is expressed exclusively in heart at embryonic day (E) 8.5, but at E 9.5 it was detected in somites in a rostral to caudal gradient, with highest expression rostrally. The somite expression pattern progresses caudally through E 11.5, corresponding to somite maturation. At this stage, cypher expression was also detected in cells migrating from the myotome. At E 13.5, cypher expression was detected throughout the embryonic musculature. The X-gal staining pattern observed here matches well with our previous RNA in situ hybridization results, with the exception that the X-gal staining was observed earlier in the somites, in keeping with its greater sensitivity (Zhou et al., 1999).

Bottom Line: Examination of striated muscle from the mutants revealed that Cypher is not required for sarcomerogenesis or Z-line assembly, but rather is required for maintenance of the Z-line during muscle function.In vitro studies demonstrated that individual domains within Cypher localize independently to the Z-line via interactions with alpha-actinin or other Z-line components.These results suggest that Cypher functions as a linker-strut to maintain cytoskeletal structure during contraction.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Medicine and Department of Medicine, University of California at San Diego School of Medicine, La Jolla, CA 92093, USA.

ABSTRACT
Cypher is a member of a recently emerging family of proteins containing a PDZ domain at their NH(2) terminus and one or three LIM domains at their COOH terminus. Cypher knockout mice display a severe form of congenital myopathy and die postnatally from functional failure in multiple striated muscles. Examination of striated muscle from the mutants revealed that Cypher is not required for sarcomerogenesis or Z-line assembly, but rather is required for maintenance of the Z-line during muscle function. In vitro studies demonstrated that individual domains within Cypher localize independently to the Z-line via interactions with alpha-actinin or other Z-line components. These results suggest that Cypher functions as a linker-strut to maintain cytoskeletal structure during contraction.

Show MeSH
Related in: MedlinePlus