Caenorhabditis elegans UNC-98, a C2H2 Zn finger protein, is a novel partner of UNC-97/PINCH in muscle adhesion complexes.
To further understand the assembly and maintenance of the muscle contractile apparatus, we have identified a new protein, UNC-98, in the muscle of Caenorhabditis elegans. unc-98 mutants display reduced motility and a characteristic defect in muscle structure. We show that the major defect in the mutant muscle is in the M-lines and dense bodies (Z-line analogs). Both functionally and compositionally, nematode M-lines and dense bodies are analogous to focal adhesions of nonmuscle cells. UNC-98 is a novel 310-residue polypeptide consisting of four C2H2 Zn fingers and several possible nuclear localization signal and nuclear export signal sequences. By use of UNC-98 antibodies and green fluorescent protein fusions (to full-length UNC-98 and UNC-98 fragments), we have shown that UNC-98 resides at M-lines, muscle cell nuclei, and possibly at dense bodies. Furthermore, we demonstrated that 1) the N-terminal 106 amino acids are both necessary and sufficient for nuclear localization, and 2) the C-terminal (fourth) Zn finger is required for localization to M-lines and dense bodies. UNC-98 interacts with UNC-97, a C. elegans homolog of PINCH. We propose that UNC-98 is both a structural component of muscle focal adhesions and a nuclear protein that influences gene expression.
Mercer
Kristina B
KB
Department of Pathology, Emory University, Atlanta, Georgia 30322, USA.
Flaherty
Denise B
DB
Miller
Rachel K
RK
Qadota
Hiroshi
H
Tinley
Tina L
TL
Moerman
Donald G
DG
Benian
Guy M
GM
D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D010641:Phenotype; D016335:Zinc Fingers / Q000235:genetics / Q000502:physiology*
D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D009124:Muscle Proteins; C117451:UNC-97 protein, C elegans; C481656:UNC-98 protein, C elegans; C490233:pin-2 protein, C elegans