Know Your Neighbors: Three Phenotypes in Null Mutants of the Myogenic bHLH Gene MRF4

摘要: The data from the MRF4, Hox, and globin studies suggest that many other knockout experiments may be subject to similar effects. examples we have discussed involve loci contain two or more related genes, these especially prone evolution of joint locus control elements interrelated cis-regulatory interactions. It is equally plausible our current picture skewed toward cases by investigator knowledge identity neighboring genes long-range effects will seen for unrelated adjacent genes. We therefore feel until substantially understood about cis-regulation over substantial regions genome it prudent consider in design interpretation. One might think direct complementation testing would clarify which knockouts are neighborhood complications, but mouse this solution not straightforward. has proved frustratingly difficult capture reintroduce into mice pieces DNA faithfully recapitulate full developmental pattern correct level expression wildtype gene. culprits appear very same aspects gene structure at work generating problem: dispersal pertinent regulatory large stretches also include additional Moreover, minigenes induced express complementing protein coding sequences, manner heat shock regulated constructions Drosophila, unreliable transgenic formats. For reasons application improved, if somewhat complex, strategies provides a immediate uncertainties. To avoid deleting sequences on one can instead introduce an effectively positioned stop codon. This coupled with removal selection cassette site-specific recombinases such as yeast Flp phage P1 Cre. Alternatively, so-called “hit-and-run” strategy, simultaneous introduction subtle nonsense missense mutations together elimination all residue (Ramirez-Solis et al. 1993xRamirez-Solis, R, Zheng, II, Whiting, J, Krumlauf, Bradley, A. Cell. 1993; 73: 279–294Abstract | Full Text PDF PubMed Scopus (227)See ReferencesRamirez-Solis 1993), used. achieves cleanest small specific mutations, calls greater effort establishing identifying desired ES cell line. Finally, existing knockouts, challenge their phenotypes attention identities activities