Understanding limb development not only gives insights into the outgrowth and differentiation of the limb, but also has clinical relevance. Limb development begins with two paired limb buds (forelimb and hindlimb buds), which are initially undifferentiated mesenchymal cells tipped with a thickening of the ectoderm, termed the apical ectodermal ridge (AER). As a transitional embryonic structure, the AER undergoes four stages and contributes to multiple axes of limb development through the coordination of signalling centres, feedback loops, and other cell activities by secretory signalling and the activation of gene expression. Within the scope of proximodistal patterning, it is understood that while fibroblast growth factors (FGFs) function sequentially over time as primary components of the AER signalling process, there is still no consensus on models that would explain proximodistal patterning itself. In anteroposterior patterning, the AER has a dual-direction regulation by which it promotes the sonic hedgehog (Shh) gene expression in the zone of polarizing activity (ZPA) for proliferation, and inhibits Shh expression in the anterior mesenchyme. In dorsoventral patterning, the AER activates Engrailed-1 (En1) expression, and thus represses Wnt family member 7a (Wnt7a) expression in the ventral ectoderm by the expression of Fgfs, Sp6/8, and bone morphogenetic protein (Bmp) genes. The AER also plays a vital role in shaping the individual digits, since levels of Fgf4/8 and Bmps expressed in the AER affect digit patterning by controlling apoptosis. In summary, the knowledge of crosstalk within AER among the three main axes is essential to understand limb growth and pattern formation, as the development of its areas proceeds simultaneously.
Animals ; Apoptosis ; Body Patterning ; Bone Morphogenetic Proteins/biosynthesis* ; Developmental Biology ; Ectoderm/metabolism* ; Extremities/embryology* ; Fibroblast Growth Factor 10/metabolism* ; Fibroblast Growth Factors/biosynthesis* ; Gene Expression Regulation ; Hedgehog Proteins/biosynthesis* ; Homeodomain Proteins/biosynthesis* ; Mesoderm/metabolism* ; Mice ; Signal Transduction ; Wnt Proteins/biosynthesis*

OBJECTIVETo investigate the expression of Shh and its receptors Ptc1 and Ptc2 mRNA in the cap stage of mouse molar and discuss its role in early tooth morphogenesis.

METHODSThe embryonic mouse heads of early tooth development (E10.5 - E15.5) were obtained and 5 micro m serial sections were made. Immunohistochemical staining of PCNA was carried out by SP method. The expression pattern of Shh, Ptc1, and Ptc2 mRNA was analysed by in situ hybridization.

RESULTSE14.5, outer dental epithelium, inner dental epithelium, stellate reticulum and underlying dental mesenchyme were PCNA positive. Most of the enamel knot cells were PCNA negative. A few of the enamel knot cells were PCNA positive. Shh, Ptc1, and Ptc2 mRNA were strongly expressed in outer dental epithelium, inner dental epithelium, stellate reticulum and the enamel knot.

CONCLUSIONIn the cap stage, Shh as a paracrine and autocrine signaling molecule might stimulate epithelium and mesenchyme proliferation.

Animals ; Hedgehog Proteins ; Mice ; Molar ; metabolism ; Patched Receptors ; Patched-1 Receptor ; RNA, Messenger ; biosynthesis ; Receptors, Cell Surface ; biosynthesis ; genetics ; Tooth Germ ; growth & development ; metabolism ; Trans-Activators ; biosynthesis

OBJECTIVETo investigate whether the sonic hedgehog signaling pathway is involved in the development of human fetal prostate, and to evaluate the changing staining patterns of its molecules, sonic hedgehog (SHH), patchedl (PTC1), smoothened (SMO), and GLI1, in the human fetal prostate at various gestation stages.

METHODSFifteen human fetal prostate specimens at various developmental stages (10 - 39 weeks) were included in this study. SHH, PTC1, SMO and GLI1 were detected in all the specimens by immunohistochemical technique. All the slides were observed and assessed under the light microscope.

RESULTSSHH, PTC1, SMO and GLI1 could be detected in human fetal prostate tissues, and their expression formed two surges, the former at week 16, and the latter at week 28. The staining of SHH and SMO was distributed only in the ductal epithelium but not in the stroma. The expression of PTC1 and GLI1 could be found mainly in the epithelium, with minimal staining in the stroma.

CONCLUSIONThe sonic hedgehog signaling pathway is involved in the development of the human fetal prostate. The high expression of its molecules at early gestation stages might be associated with the induction of prostatic buds, while their abundant expression at later gestation stages might be related to the prostate ductal branching, growth, differentiation and morphogenesis.

Gene Expression Regulation, Developmental ; physiology ; Hedgehog Proteins ; biosynthesis ; Humans ; Male ; Oncogene Proteins ; biosynthesis ; Patched Receptors ; Prostate ; embryology ; metabolism ; Receptors, Cell Surface ; biosynthesis ; Receptors, G-Protein-Coupled ; biosynthesis ; Signal Transduction ; physiology ; Smoothened Receptor ; Trans-Activators ; biosynthesis ; Zinc Finger Protein GLI1

OBJECTIVETo investigate the expression and biological effect of Shh during late bell stage by morphological and semi-quantitative analysis.

METHODSTooth germs were selected from new born Bal b/c mouse (P1, P2, P3, P5, P7). Semi-quality of Shh was measured by Western Blot and the expression place and strength of Shh were observed by in situ hybridization.

RESULTSShh was expressed in the ameloblast layer during late bell stage; the expression strength was high in secretive period and decreased with development; the active N-section was detectable before P3.

CONCLUSIONShh expresses specially in the ameloblast layer in late bell stage, and expression quality is related to the function of ameloblasts.

Ameloblasts ; metabolism ; Animals ; Blotting, Western ; Gene Expression ; Hedgehog Proteins ; In Situ Hybridization ; In Vitro Techniques ; Mice ; Mice, Inbred BALB C ; Tooth Germ ; cytology ; metabolism ; Trans-Activators ; biosynthesis ; genetics

OBJECTIVETo study the expression of Smo protein and the downstream transcription factor Gli1 protein in Sonic hedgehog signal transduction pathway in gastric carcinoma.

METHODSA tissue microarray was constructed using 85 gastric carcinoma and 25 normal gastric mucosa specimens. The expression of Smo and Gli1 proteins were detected immunohistochemically and the correlation between their expression in gastric carcinoma was analyzed.

RESULTSOnly weak expression, if any, of Smo and Gli1 proteins was detected in normal gastric mucosa, but in papillary adenocarcinoma, tubular adenocarcinoma and poorly differentiated adenocarcinoma, their expressions were significant increased as the differentiation degree was lowered. Smo protein expression in gastric carcinoma was significantly correlated with that of Gli1 protein with correlation coefficient of 0.989 (P<0.001).

CONCLUSIONThe abnormal activity of Sonic hedgehog signal transduction pathway may play an important role in the occurrence of papillary adenocarcinoma, tubular adenocarcinoma and poorly differentiated adenocarcinoma, and this abnormality is associated with Smo protein overexpression, which upregulates the expression of the downstream transcription factor Gli1 protein.

Adenocarcinoma ; metabolism ; pathology ; physiopathology ; Adult ; Aged ; Female ; Hedgehog Proteins ; physiology ; Humans ; Immunohistochemistry ; Male ; Middle Aged ; Receptors, G-Protein-Coupled ; biosynthesis ; Signal Transduction ; Smoothened Receptor ; Stomach Neoplasms ; metabolism ; pathology ; physiopathology ; Transcription Factors ; biosynthesis ; Zinc Finger Protein GLI1