PgmNr Z582: Cure modeling human genetic skeletal muscle disorders.

Authors:
N. Umemoto; M. Urban; R. Harm; M. McNulty; K. Predmore; M. Serres; C. Daby; H. Sizek; C. Bullard; D. Hunter; X. Xu; K. Clark; S. Ekker


Institutes
Mayo Clinic, Rochester, MN.


Abstract:

Background: Approved treatments are available for only ~5 percent of the thousands of known rare diseases. In particular, almost all neuromuscular disorders are considered orphan diseases caused by single gene defect. However, there are few approved drugs for the disorders. To overcome the bottleneck in drug discovery for these rare diseases, we hypothesize that the use of a new concept we call "cure modeling" can be used to augment traditional disease modeling such as gene knock-out animals. 
Methods: To explore and identify the molecular mechanisms and signatures of health from these genetic skeletal muscle diseases, we have deployed our genome engineering technology to construct reversible mutant alleles, Protein Trap Gene-break Transposon (GBT) system in zebrafish. The main features of the GBT system are; i) GBT constructs are integrated in zebrafish genome using transposons and mapped using next gen sequencing; ii) >95% of the time, GBT alleles show 99% knockdown of the tagged endogenous transcripts; iii) mRFP reporter expression shows specific localization of the gene product; iv) Cre recombinase can be used to revert the mutant locus to wild-type function. 
Results and Discussion:  We have created 5 GBT cure models that have the mutant locus in orthologous zebrafish genes (ano5a, ryr1b, dnajb6b, casq1a and gyg1a) associated with human genetic disorders in skeletal muscle. To assess functional phenotypes of skeletal muscle in the GBT fish lines compared with or without exercise, we are screening the alteration of tcap expression, a molecular marker rapidly induced by skeletal muscle activity. Here, we report details about our findings from this unique functional phenotypic assay. These initial revertible mutants exhibit how cure modeling can represent an idealized therapy to treat a tested genetic disease at the level of transcripts, proteins, metabolites and other molecular components.



ZFIN Genetics Index
1. ano5a
2. ryr1b
3. dnajb6b
4. casq1a
5. gyg1a