Location
Philadelphia, PA
Start Date
17-4-2026 1:30 PM
End Date
17-4-2026 2:30 PM
Description
Introduction: The metatarsal (MT) bones of the feet form a single growth plate. The growth plate of MT1 in the first digit forms at the proximal end, whereas in digits 2-5 the MT growth plates occur distally. We used RNA sequencing of MT1 and MT3 to compare growth plate-forming and non-forming ends to identify differentially expressed genes (DEGs) associated with growth plate formation. We then compared DEGs shared between MT1 and MT3 at three different time points: postnatal day (P)0, P4, and P9. Two genes with shared differential expression among the distal MT1 and MT3 at all ages are Tenm1 and Epha7.
Tenm1 (Teneurin-1) encodes a large transmembrane glycoprotein that mediates cell-cell adhesion and contributes to developmental patterning. Although most extensively studied in the nervous system, emerging evidence suggests broader roles in developmental tissue organization. Epha7 encodes an Eph receptor tyrosine kinase. Eph/ephrin signaling regulates cell positioning, boundary formation, proliferation, and differentiation during embryonic development and skeletal patterning.
Objective: To further define the role of Tenm1 and Epha7 during bone formation, we performed in situ hybridization to compare their spatial expression patterns in distal and proximal neonatal mouse MTs.
Methods: Hind limbs were collected from FVB/NJ mice. Samples were fixed in an RNase-free preparation of 4% paraformaldehyde and decalcified in RNase-free Morse’s solution (22.5% formic acid and 10% sodium citrate) for 24 hours, and embedded in paraffin following standard procedures. In situ hybridization (ISH) was performed on paraffin-embedded sections using RNAscopeTM 2.5 HD Assay-RED (ACD Bio) probes for Tenm1 and Epha7, following the standard RNAscopeTM protocol with modification using a proprietary antigen retrieval enzyme optimized for bone and cartilage tissue.
Results: Tenm1 expression is strongest in the distal epiphyseal chondrocytes at all three ages of both MT1 and MT3. It is not found in the proximal epiphyses of the MT3 and only present in the proximal end of the MT1 at P0. Tenm1 is also expressed in the perichondrium and periosteum. At P9, its expression in the distal epiphyses appears to be associated with ligamentous insertions.
Epha7 expression is particularly strong in the early hypertrophic chondrocytes of the growth plates of both MT1 and MT3. Expression begins to be reduced in the corresponding zones of the non-growth plate forming ends. At P9, expression is observed in early hypertrophic cells surrounding the primary center of ossification. Beyond hypertrophic chondrocytes, Epha7 is also observed in the perichondrium and periosteum.
Conclusion: The spatial expression patterns of Tenm1 and Epha7 largely match our quantitative RNA-seq data. Tenm1 has a clear bias towards distal expression and may be associated with the formation of ligamentous attachments. Epha7 shows striking expression in early hypertrophic chondrocytes and may have a role in growth plate regulation. However, it is also strongly expressed in the perichondrium which may explain the greater overall expression detected in distal MTs.
Embargo Period
6-3-2027
Tenm1 and Epha7 expression during distal metatarsal ossification
Philadelphia, PA
Introduction: The metatarsal (MT) bones of the feet form a single growth plate. The growth plate of MT1 in the first digit forms at the proximal end, whereas in digits 2-5 the MT growth plates occur distally. We used RNA sequencing of MT1 and MT3 to compare growth plate-forming and non-forming ends to identify differentially expressed genes (DEGs) associated with growth plate formation. We then compared DEGs shared between MT1 and MT3 at three different time points: postnatal day (P)0, P4, and P9. Two genes with shared differential expression among the distal MT1 and MT3 at all ages are Tenm1 and Epha7.
Tenm1 (Teneurin-1) encodes a large transmembrane glycoprotein that mediates cell-cell adhesion and contributes to developmental patterning. Although most extensively studied in the nervous system, emerging evidence suggests broader roles in developmental tissue organization. Epha7 encodes an Eph receptor tyrosine kinase. Eph/ephrin signaling regulates cell positioning, boundary formation, proliferation, and differentiation during embryonic development and skeletal patterning.
Objective: To further define the role of Tenm1 and Epha7 during bone formation, we performed in situ hybridization to compare their spatial expression patterns in distal and proximal neonatal mouse MTs.
Methods: Hind limbs were collected from FVB/NJ mice. Samples were fixed in an RNase-free preparation of 4% paraformaldehyde and decalcified in RNase-free Morse’s solution (22.5% formic acid and 10% sodium citrate) for 24 hours, and embedded in paraffin following standard procedures. In situ hybridization (ISH) was performed on paraffin-embedded sections using RNAscopeTM 2.5 HD Assay-RED (ACD Bio) probes for Tenm1 and Epha7, following the standard RNAscopeTM protocol with modification using a proprietary antigen retrieval enzyme optimized for bone and cartilage tissue.
Results: Tenm1 expression is strongest in the distal epiphyseal chondrocytes at all three ages of both MT1 and MT3. It is not found in the proximal epiphyses of the MT3 and only present in the proximal end of the MT1 at P0. Tenm1 is also expressed in the perichondrium and periosteum. At P9, its expression in the distal epiphyses appears to be associated with ligamentous insertions.
Epha7 expression is particularly strong in the early hypertrophic chondrocytes of the growth plates of both MT1 and MT3. Expression begins to be reduced in the corresponding zones of the non-growth plate forming ends. At P9, expression is observed in early hypertrophic cells surrounding the primary center of ossification. Beyond hypertrophic chondrocytes, Epha7 is also observed in the perichondrium and periosteum.
Conclusion: The spatial expression patterns of Tenm1 and Epha7 largely match our quantitative RNA-seq data. Tenm1 has a clear bias towards distal expression and may be associated with the formation of ligamentous attachments. Epha7 shows striking expression in early hypertrophic chondrocytes and may have a role in growth plate regulation. However, it is also strongly expressed in the perichondrium which may explain the greater overall expression detected in distal MTs.