Two LIM domain proteins and UNC-96 link UNC-97/pinch to myosin thick filaments in Caenorhabditis elegans muscle.
By yeast two-hybrid screening, we found three novel interactors (UNC-95, LIM-8, and LIM-9) for UNC-97/PINCH in Caenorhabditis elegans. All three proteins contain LIM domains that are required for binding. Among the three interactors, LIM-8 and LIM-9 also bind to UNC-96, a component of sarcomeric M-lines. UNC-96 and LIM-8 also bind to the C-terminal portion of a myosin heavy chain (MHC), MHC A, which resides in the middle of thick filaments in the proximity of M-lines. All interactions identified by yeast two-hybrid assays were confirmed by in vitro binding assays using purified proteins. All three novel UNC-97 interactors are expressed in body wall muscle and by antibodies localize to M-lines. Either a decreased or an increased dosage of UNC-96 results in disorganization of thick filaments. Our previous studies showed that UNC-98, a C2H2 Zn finger protein, acts as a linkage between UNC-97, an integrin-associated protein, and MHC A in myosin thick filaments. In this study, we demonstrate another mechanism by which this linkage occurs: from UNC-97 through LIM-8 or LIM-9/UNC-96 to myosin.
Qadota
Hiroshi
H
Department of Pathology, Emory University, Atlanta, GA 30322, USA.
Mercer
Kristina B
KB
Miller
Rachel K
RK
Kaibuchi
Kozo
K
Benian
Guy M
GM
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D060588:LIM Domain Proteins; D009124:Muscle Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding
D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D018398:Homeodomain Proteins; D060588:LIM Domain Proteins; C525961:Lim-8 protein, C elegans; C525958:Lim-9 protein, C elegans; D009124:Muscle Proteins; C514106:UNC-96 protein, C elegans; C117451:UNC-97 protein, C elegans; D009218:Myosins