Dr. Yang co-invented, with Nathaniel Heintz and Peter Model, the first method to engineer Bacterial Artificial Chromosomes (BACs) to generate transgenic mice. BACs have the advantage of holding hundreds of thousands of base pairs of genomic DNA, while being relatively stable and easy to work with. For the vast majority of genes in the mammalian genome, the BAC transgenes encompass not only the coding region but also regulatory elements to confer reproducible transgene expression in vivo. The BAC transgenic approach has become a widely used and often preferred method to generate transgenic animals, from zebrafish to mamamals. Both BAC and conventional transgenic methods have been used by the Yang lab to develop and characterize several important disease models.
BACHD and BACHD-L: A human BAC containing the entire 170 kb human Huntingtin (htt) genomic locus was modified by replacing the human htt exon 1 with a loxP-flanked human mutant htt exon 1 sequence containing 97 mixed CAA-CAG repeats encoding a continuous polyglutamine (polyQ) stretch.
BAC-WT: This mouse model was generated as a control for the BACHD model. This mouse model was generated with same human BAC containing the htt genomic locus but with 21 CAG repeats.
RosaHD: This HD mouse model was created as a knockin using a targeting vector designed with a loxP-flanked transcriptional STOP sequence immediately upstream of a polyQ-mutant form of the human Huntingtin protein exon 1 (mhtt-exon1) sequence containing 103 mixed CAA-CAG repeats, each encoding glutamine, into the Gt(ROSA)26Sor locus.
BACHD-SA and BACHD-SD: Similar to the BACHD model, these HD mouse models were further modified by nucleotide substitutions that resulted in amino acid substitutions of alanine (SA) or asparagine (SD) for serine at positions 13 and 16.
BACHD-∆N17 and BAC-WT-∆N17: Similar to the BACHD model, these HD mouse models were generated with the BACHD (BACHD-∆N17) and BAC-WT constructs (BAC-WT-∆N17) which were further modified by nucleotide deletion that resulted in the loss of amino acids 2 to 16 in the N17 domain.
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Huntington’s Disease-Like 2:
HDL2-C and JPH3-GFP: The human BAC containing the entire JPH3 genomic locus was modified by inserting 120 CTG/CAG repeats into exon 2A to generate the HDL2-C line. Using the same human BAC containing the JPH3 genomic locus, a GFP sequence followed by a loxP-flanked STOP sequence (neo cassette and triple polyadenylation signal) was placed in front of the translation initiation codon of exon 1 to generate the JPH3-GFP line.
PARK2-Q311X: The mouse BAC containing the entire Slc6a3 genomic locus was modified by inserting a parkin-Q311X cDNA sequence, which is a FLAG-tagged mutant human parkin gene (PARK2) carrying the Q311X truncation associated with Turkish early-onset Parkinson’s disease, into Slc6a3 exon 2 upstream of the translation initiation codon.
BAC-aSyn and BAC-aSyn120: This transgenic mouse model expresses the human BAC containing the entire SNCA locus which was modified to possess loxP sites on either side of exon 2. When crossed to a strain expressing Cre recombinase, human aSyn expression can be reduced in a cell-specific manner. Similar to the BAC-aSyn model, but these mouse models express a truncated form of the human aSyn.
Basal Ganglia Circuitry and Opiate Addiction:
GPR6 mice: The endogenous GPR6 was targeted and disrupted by an in-frame insertion of a lacZ reporter gene.