Worm Breeder's Gazette 13(5): 28 (February 1, 1995)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Johns Hopkins University, Baltimore MD 21218 We have identified and characterized 12 genes, designated mua (for muscle attachment), that are required for maintaining muscle to cuticle attachments (WBG 12.3). Phenotypically, these mutations are reminiscent of the muscular dystrophies of vertebrates. One intriguing possibility raised by our studies is that a tension-activated feedback system may regulate muscle attachment formation in C. elegans. We have previously reported the cloning of mua-3 (WBG v13.3), which encodes a novel matrix receptor protein, and have recently cloned mua-1. mua-1(rh160) causes a progressive detachment of the body-wall muscles from the hypodermis and cuticle during larval growth. About 20% of L1 larvae, 80% of L2 and over 90% of adults are affected. The initial detachment is often in either the head or midbody where intact muscle bands pull away from a small region of their normal attachments. Subsequent larger regions of detachment and occasional breaks between adjacent muscles within the bands are observed. There is a ventral bias, 74% of the affected L2s (and 54% of adults) show only ventral detachment. rh160 animals often display additional defects, which are presumably secondary consequences of the body-wall muscle defect. These include aberrant gonadal morphologies, egg laying defects due to loss of vulval muscle attachments, and death due to eversion of the uterus through the vulva. However, in rh160 homozygous adults with intact body-wall muscles anal depressor muscle and pharyngeal musculature are unaffected. These observations suggest that mua-1 activity is specific to the body- wall muscles. We have cloned mua-1 by genetic mapping and microinjection rescue. Rescuing activity is contained within an 8 kb SpeI to HindIII fragment of cosmid F54H5. Deleting DNA on either side of a KpnI site within the fragment abolishes its activity. We sequenced outwards from this KpnI site, and aligned our sequence with the genomic sequence of F54H5 obtained from the Sequencing Project. The predicted MUA1 protein (246 aa) comprises a potential N terminal activating region and three C terminal C2 H2 zinc-fingers. The KpnI site lies between the N terminal and the zinc- finger portions of the protein. MUA1 is most closely related to human BTEB2 and mouse erythroid Krupple-like factor (EKLF), members of sub-family of GC box binding transcriptional regulators. An analysis of the zinc-finger domains of these proteins, and the closely related Sp1 and the Wilms-Tumor WT1 , shows MUA1 to be more distantly related to BTEB2 and EKLF than they are to each other. Both these proteins show organ specific expression patterns but neither is expressed in muscle, raising the possibility that a vertebrate MUA1 remains to be identified. If such a gene exists, we predict mutations in it might result in a dystrophic muscle phenotype. mua1.........SNKRNPTDKKFVVHACTYPGCFKKYSKSSHLKAHERTHSGEKPFVCKWQNCSWKFA bteb2human...NRRS**DLE*RRI*Y*D****T*V*T********L***T****YK*T*EG*D*R** eklfmus.TAPPKRSR*TLAP*RQAA*T*GHE**G*S**********L***T****YA*S*DG*D*R** btebrat.....SGVASKGKHASEKR*K*P*S**G*V*G********Y*V*T**R**P*T*PD*LK**S Sp1 rat...................*I*HIQ**G*V*G*T***R**L*W*T**R**M*N*SY*GKR*T WT1 rat.............TSEKRPFM*A****N*R*F*L***QM*S*K*T****YQ*DFKD*ERR*S mua-1..RSEELTRHMRKHTGDKPFRCSLCDRNFARSDHLSLHMKRHSTI bteb2..**D*****Y*****A***Q*GV*N*S*S*****A******QN eklf...**D*****Y*****HR**C*G**P*A*S*****A******L bteb...**D*****Y*T***E*Q***P**EKR*M*****TK*AR**TDFHPSMIKRSKKALASPL Sp1....**D**Q**K*T***E*K*A*PE*PKR*M*****K*I*T*QNKK.... WT1....**DQ*K**Q*R***V***Q*KT*Q*K*S*****KT*TRT*TGKTSEKPFSCRWHSCQKKFARSDE LVRHHNMHQRNMTKLQLAL