IpitationTestis protein extracts were prepared in lysis buffer containing 50 mM Tris-HCl, 150 mM NaCl, 1 NP-40, 2 mM MgCl2, 50 U/ml benzonase nuclease (Sigma), protease inhibitor cocktail (Calbiochem) and 5 mM get (��)-Hexaconazole sodium orthovanadate). The lysates were pre-cleared overnight with unconjugated agarose. 20 mg of affinity purified goat GGN1 antibody [8] and goat IgG were separately conjugated to resin using an AminoLink Plus Immobilisation kit (Thermo Scientific) as per manufacturer’s instructions. Equal amounts 25033180 of testis extracts (4 mg) were added to the GGN1 or goat IgG column and incubated overnight at 4uC. Following extensive washing with PBS, bound protein complexes were eluted with 0.1 M glycine (pH 2.7) and separated on SDSPAGE. Immunoblotting was performed using antibodies against FANCA at 2 mg/ml (ab97578, Abcam) FANCL at 2.5 mg/ml (ab94458, Abcam), FANCD2 at 1 mg/ml (ab2187, Abcam), FANCI at 2 mg/ml (ab74332, Abcam), BRCA1 at 0.2 mg/ml (sc646, Santa Cruz) and BRCC36 at 0. 25 mg/ml (ab115172, Abcam), and detected using ECL Plus (GE Bioscience). FANCL, FANCD2 and BRCC36 antibodies were used for reciprocal IPs as described above. Of these, FANCL antibody was unable to pull down FANCL protein. To confirm verify haploinsufficiency, 20 mg of spermatocyte protein extracts were loaded and probed with GGN1 antibody at 1 mg/ml.Materials and Methods Generation of the Ggn Knockout MiceAnimal experiments were approved by the Monash University and the University of Queensland Animal Ethics Committees. A 2.6 kb DNA fragment containing the entire protein-coding region of the Ggn gene was replaced with a 1.8 kb Kanamycin-Neomycin cassette (Figure 1A). Gene targeting was performed using the R1 ES cells (129X1/SvJ6129Sl) [35] purchased from Prof. Andras Nagy (Samuel Lunenfeld Research Terlipressin Institute, Toronto, Canada). The targeted ES clones were verified by Southern blotting (Figure 1B). Two independent targeted ES clones were injected into C57BL/6 blastocysts and the resulting male chimeras mated with C57BL/6 females to establish knockout mouse lines and subsequently backcrossed onto C57BL/6J for 12 generations. Both lines exhibited identical phenotypic defects. Genotyping of 3 weeks-old pups and post-implantation embryos was performed by multiplex PCR using two primer pairs: GGNa-Fw+GGNa-Rev and NeoR-Fw+NeoR-Rev (Table S1), whereby the wild-type alleles gave a band of 285 bp and the knockout allele gave a band of 537 bp. Genotyping of pre-implantation embryos was performed using a nested PCR strategy, whereby 1 ml from the first 1317923 round of PCR amplification (using primers GGNa-Fw+GGNaRev and NeoR-Fw+NeoR-Rev) was used as a template for the second round of PCR amplification using primers: GGNbFw+GGNb-Rev and 2ndNeo-Fw +2ndNeo-Rev (Table S1). The wild-type Ggn allele gave a 360 bp product and the knockout alleles gave a 220 bp product.Meiotic SpreadMeiotic spreads were prepared as previously described from postnatal day 17?9 mice [38]. DSBs were visualised with a RAD51 antibody at 8 mg/ml (sc-8349, Santa Cruz), and progression through meiosis was marked with a SYCP3 antibody at 4 mg/ml (sc-74569, Santa Cruz). The first 50 pachytene spermatocytes for 7 Ggn+/2 and Ggn+/2 mice were photographed. Pachynema was defined as the presence of fully synapsed chromosomes i.e. no gaps. Foci on autosomes and the XY body were recorded separately. Statistical significance was determined using a student’s t-test was used to compare the means of two populations. P values ,0.0.IpitationTestis protein extracts were prepared in lysis buffer containing 50 mM Tris-HCl, 150 mM NaCl, 1 NP-40, 2 mM MgCl2, 50 U/ml benzonase nuclease (Sigma), protease inhibitor cocktail (Calbiochem) and 5 mM sodium orthovanadate). The lysates were pre-cleared overnight with unconjugated agarose. 20 mg of affinity purified goat GGN1 antibody [8] and goat IgG were separately conjugated to resin using an AminoLink Plus Immobilisation kit (Thermo Scientific) as per manufacturer’s instructions. Equal amounts 25033180 of testis extracts (4 mg) were added to the GGN1 or goat IgG column and incubated overnight at 4uC. Following extensive washing with PBS, bound protein complexes were eluted with 0.1 M glycine (pH 2.7) and separated on SDSPAGE. Immunoblotting was performed using antibodies against FANCA at 2 mg/ml (ab97578, Abcam) FANCL at 2.5 mg/ml (ab94458, Abcam), FANCD2 at 1 mg/ml (ab2187, Abcam), FANCI at 2 mg/ml (ab74332, Abcam), BRCA1 at 0.2 mg/ml (sc646, Santa Cruz) and BRCC36 at 0. 25 mg/ml (ab115172, Abcam), and detected using ECL Plus (GE Bioscience). FANCL, FANCD2 and BRCC36 antibodies were used for reciprocal IPs as described above. Of these, FANCL antibody was unable to pull down FANCL protein. To confirm verify haploinsufficiency, 20 mg of spermatocyte protein extracts were loaded and probed with GGN1 antibody at 1 mg/ml.Materials and Methods Generation of the Ggn Knockout MiceAnimal experiments were approved by the Monash University and the University of Queensland Animal Ethics Committees. A 2.6 kb DNA fragment containing the entire protein-coding region of the Ggn gene was replaced with a 1.8 kb Kanamycin-Neomycin cassette (Figure 1A). Gene targeting was performed using the R1 ES cells (129X1/SvJ6129Sl) [35] purchased from Prof. Andras Nagy (Samuel Lunenfeld Research Institute, Toronto, Canada). The targeted ES clones were verified by Southern blotting (Figure 1B). Two independent targeted ES clones were injected into C57BL/6 blastocysts and the resulting male chimeras mated with C57BL/6 females to establish knockout mouse lines and subsequently backcrossed onto C57BL/6J for 12 generations. Both lines exhibited identical phenotypic defects. Genotyping of 3 weeks-old pups and post-implantation embryos was performed by multiplex PCR using two primer pairs: GGNa-Fw+GGNa-Rev and NeoR-Fw+NeoR-Rev (Table S1), whereby the wild-type alleles gave a band of 285 bp and the knockout allele gave a band of 537 bp. Genotyping of pre-implantation embryos was performed using a nested PCR strategy, whereby 1 ml from the first 1317923 round of PCR amplification (using primers GGNa-Fw+GGNaRev and NeoR-Fw+NeoR-Rev) was used as a template for the second round of PCR amplification using primers: GGNbFw+GGNb-Rev and 2ndNeo-Fw +2ndNeo-Rev (Table S1). The wild-type Ggn allele gave a 360 bp product and the knockout alleles gave a 220 bp product.Meiotic SpreadMeiotic spreads were prepared as previously described from postnatal day 17?9 mice [38]. DSBs were visualised with a RAD51 antibody at 8 mg/ml (sc-8349, Santa Cruz), and progression through meiosis was marked with a SYCP3 antibody at 4 mg/ml (sc-74569, Santa Cruz). The first 50 pachytene spermatocytes for 7 Ggn+/2 and Ggn+/2 mice were photographed. Pachynema was defined as the presence of fully synapsed chromosomes i.e. no gaps. Foci on autosomes and the XY body were recorded separately. Statistical significance was determined using a student’s t-test was used to compare the means of two populations. P values ,0.0.
