Figure 2. Robust versus quiescent states of Bmp2 expression reflect active versus homeostatic states of periosteal bone growth.

LacZ staining on tissues from mice expressing beta-galactosidase from one allele of the endogenous Bmp2 locus (Bmp2^lacz/+). (a) Lateral view of a whole mount E13.5 Bmp2^lacz/+ mouse embryo, representative of other Bmp2^lacz/+ littermates. (b,c) Longitudinal sections through the (b) forelimb or (c) hindlimb of E14.5 Bmp2^lacz/+ mouse embryos. (d,e) Longitudinal sections of (d) digits or (e) radius/ulna of newborn Bmp2^lacz/+ mice. (f–l) Longitudinal sections through cortical femoral bone from (f) 7 day-old, (g) 14 day-old, (h) 21 day-old or (i) 6 month-old Bmp2^lacz/+ mice. Abbreviations: PO (periosteum), CB (cortical bone), or MA (marrow) in brackets. (j–l) Standardized fractures were established in femurs of Bmp2^lacz/+ and WT littermate mice (n = 3). (k,l) LacZ staining 3 days post-fracture in (k) Bmp2^lacz/+ or (l) negative control WT mice.

Figure 2—figure supplement 1. Schematic of the Bmp2^lacz knock-in allele.

Homologous recombination was used to replace the first 336 coding nucleotides of murine Bmp2 with non-membrane targeted bacterial beta-galactosidase. (a) Specifics of allele construction from the UC Davis Knock Out Mouse Project repository, Velocigene project ID 12406. (b) Schematic of the targeting strategy and the ZEN-Ub1 replacement cassette. (c) Genomic view of targeted locus visualized with the publicly-available Ensembl genome browser (www.ensembl.org).

Figure 2—figure supplement 2. Bmp2 expression domain during periosteal bone growth.

(a) LacZ staining on tissues from mice expressing beta-galactosidase from the endogenous Bmp2 locus (Bmp2^lacz/+). Longitudinal sections through the (a) forelimb of an E14.5 Bmp2^lacz/+ mouse embryo, (b) forelimb of a newborn Bmp2^lacz/+ mouse, or (c) humerus of a 2 week-old Bmp2^lacz/+ mouse. Black bar indicates LacZ expression domain in the PO (periosteum), CB (cortical bone), or MA (marrow) in brackets.