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. 2006 Apr;26(7):2615–2625. doi: 10.1128/MCB.26.7.2615-2625.2006

FIG. 3.

FIG. 3.

(A) Schematic diagram of the mouse SCL locus and the SV/PLAP/+19 transgenic reporter. SV, simian virus 40 minimal promoter; hPLAP, human placental alkaline phosphatase; 19, a 644-bp fragment of the mouse SCL locus, +19 kb from promoter 1a. (B) The SCL +19 core enhancer directs expression to the adult skeleton. Histological analysis of PLAP expression in mice carrying the SV/PLAP/+19 transgene (line 1772). (i) Longitudinal section of a femur from an adult transgenic mouse showing expression of PLAP in osteocytes (arrow), osteoblasts (solid arrow), and endothelium (arrowhead). (ii) Magnified view of the boxed area in panel i. (iii) There was no PLAP staining in the femur of wild-type littermate controls. (iv) Longitudinal section of the distal femur showing PLAP expression in chondrocytes (arrow) in the articular cartilage of adult transgenic mice. (v) Magnified view of articular chondrocytes from panel iv. (vi) There was no staining in articular chondrocytes (arrow) of littermate controls. B, bone; BM, bone marrow; C, cartilage. (C) The SCL +19 core enhancer directs expression to the developing skeleton. (i and ii) Cryosections of E16.5 embryos. (i) A longitudinal section of vertebrae from a transgenic embryo showing PLAP-positive cells (blue-purple) in the perichondrium and within ossifying cartilage. (ii) Vertebrae of E16.5 wild-type embryos do not stain for PLAP. (D) The SCL +19 core enhancer targets osteoblasts but not chondrocytes in the developing skeleton. (i to iv) Immunohistochemistry on serial sections of E12.5 embryos. (i) Section of a cervical vertebral body showing expression of the PLAP transgene (detected by immunohistochemistry and stained red) in cells within the perichondrium (arrow). (ii) Osteoblasts (detected using a collagen 1 antibody and stained brown) are not seen in the perichondrium (arrow) at this stage. (iii) Chondrocytes (detected using a collagen 2 antibody and stained brown) fill the vertebral anlage. (iv) The isotype control shows no staining. (v to viii) Immunohistochemistry on serial sections of E13.5 embryos. (v) Section through a cervical vertebral body showing PLAP-positive cells (red) in the perichondrium (arrow) and within the bone anlage (solid arrow). (vi) Osteoblasts (stained brown) are present in the perichondrium and correspond to the distribution of PLAP-positive cells (arrow and solid arrow) in panel v. (vii) Chondrocytes (stained brown) fill the cartilaginous core of the vertebral body. (viii) The isotype control shows no staining. (ix to xii) Immunohistochemistry on serial sections of E14.5 embryos, with sections corresponding to those of E13.5 embryos in panels v to viii. (E) The SCL +19 core enhancer also directs expression to the endothelium and vascular smooth muscle. (i) Section of a kidney from an adult transgenic mouse showing expression of the PLAP transgene (detected by immunohistochemistry and stained red) in the endothelium and smooth muscle wall of a branch of the renal artery (a). (ii) Magnified view of the boxed area in panel i showing PLAP expression in endothelial cells (arrow) and smooth muscle cells (arrowhead). W, wall. (iii) An adjacent section stained with an anti-CD31 (PECAM) antibody showing staining (brown) of the endothelium but not smooth muscle. (iv) Magnified view of the boxed area in panel iii showing endothelial staining (arrow). (v) An adjacent section stained with an anti-smooth muscle actin antibody showing staining (brown) of the smooth muscle wall. (vi) Magnified view of the boxed area in panel v showing staining of the wall but no staining in the endothelium (arrow). (vii) An adjacent section used as a negative (isotype) control. (viii) Magnified view of the boxed area in panel vii showing no staining in either the vessel wall or the endothelial lining.