Location
Philadelphia, PA
Start Date
17-4-2026 1:30 PM
End Date
17-4-2026 2:30 PM
Description
Growth plates preserve regions of cartilage that are the site of longitudinal skeletal growth. They contain distinct zones of proliferating and differentiating chondrocytes that allow for rapid growth of the bone.
Parathyroid hormone-like hormone (Pthlh) is expressed by reserve zone chondrocytes at the top of the growth-plate to keep underlying columnar chondrocytes in a proliferative state. As these cells differentiate and begin to undergo hypertrophy, they express Indian hedgehog (Ihh), which signals back to reserve chondrocytes to promote Pthlh expression. This produces a feedback loop that preserves a pool of proliferating chondrocytes.
The metatarsal (MT) bones in the feet form a single growth plate. Previously, we observed that Pthlh is lost in the non-growth plate forming end of the MT. Here we use RNA sequencing to compare the growth plate forming and non-forming ends of the mouse MT3 to identify additional differentially expressed genes (DEGs) associated with growth plate formation.
Slc14a1 is differentially expressed in distal postnatal day (P) 0, P4 and P9 MTs and encodes a membrane glycoprotein of a urea transporter (UT-B) that is expressed in erythrocytes and the kidney. However, Slc14a1’s role during bone formation has not been thoroughly investigated.
Objective: To understand the role of Slc14a1 during bone formation, we performed in situ hybridization (ISH) to compare its spatial expression patterns in the growth plate forming and non-forming ends of neonatal mouse MTs.
Methods: Histological specimens were collected from hind limbs of P0, P4, and P9 FVB/NJ mice. Samples were fixed in an RNase-free preparation of 4% paraformaldehyde and decalcified in an RNase-free preparation of Morse’s solution (22.5% formic acid and 10% sodium citrate) for 24 hours. We performed ISH on paraffin-embedded sections using RNAscope™ 2.5 HD Assay-RED (ACD Bio) for Slc14a1 following RNAscope™ standard protocol, except replacing standard antigen retrieval processes with the use of an RNAscope™ proprietary antigen retrieval enzyme for bone and cartilage tissue.
Results: At P0, Slc14a1 is primarily expressed in round epiphyseal chondrocytes adjacent to the growth plate and throughout the columnar zones at both ends. At P4, expression is more intense at the epiphyseal/columnar chondrocyte boundary of the distal end, while expression remains more diffuse in the proximal columnar zone. At P9, expression is localized to the epiphyseal/columnar zone boundary in the distal growth plate, and it is absent in the proximal end. Slc14a1 also shows progressively greater expression in the marrow cavity of the primary ossification center from P0 to P9.
Conclusion: Slc14a1 is expressed during growth plate formation and becomes more localized to the reserve zone chondrocytes in the distal P9 MT. The pattern of Slc14a1 expression in the reserve zone echoes that of the Pthlh with stronger expression in the growth plate forming end of the MT. While understanding of the role of this gene in bone biology is limited, it is possible that it may be involved in the PTHrP/Ihh feedback loop, suggesting possible implications of Slc14a1 in ossification of the epiphysis.
Embargo Period
6-4-2027
Expression of Slc14a1 during Growth Plate Formation
Philadelphia, PA
Growth plates preserve regions of cartilage that are the site of longitudinal skeletal growth. They contain distinct zones of proliferating and differentiating chondrocytes that allow for rapid growth of the bone.
Parathyroid hormone-like hormone (Pthlh) is expressed by reserve zone chondrocytes at the top of the growth-plate to keep underlying columnar chondrocytes in a proliferative state. As these cells differentiate and begin to undergo hypertrophy, they express Indian hedgehog (Ihh), which signals back to reserve chondrocytes to promote Pthlh expression. This produces a feedback loop that preserves a pool of proliferating chondrocytes.
The metatarsal (MT) bones in the feet form a single growth plate. Previously, we observed that Pthlh is lost in the non-growth plate forming end of the MT. Here we use RNA sequencing to compare the growth plate forming and non-forming ends of the mouse MT3 to identify additional differentially expressed genes (DEGs) associated with growth plate formation.
Slc14a1 is differentially expressed in distal postnatal day (P) 0, P4 and P9 MTs and encodes a membrane glycoprotein of a urea transporter (UT-B) that is expressed in erythrocytes and the kidney. However, Slc14a1’s role during bone formation has not been thoroughly investigated.
Objective: To understand the role of Slc14a1 during bone formation, we performed in situ hybridization (ISH) to compare its spatial expression patterns in the growth plate forming and non-forming ends of neonatal mouse MTs.
Methods: Histological specimens were collected from hind limbs of P0, P4, and P9 FVB/NJ mice. Samples were fixed in an RNase-free preparation of 4% paraformaldehyde and decalcified in an RNase-free preparation of Morse’s solution (22.5% formic acid and 10% sodium citrate) for 24 hours. We performed ISH on paraffin-embedded sections using RNAscope™ 2.5 HD Assay-RED (ACD Bio) for Slc14a1 following RNAscope™ standard protocol, except replacing standard antigen retrieval processes with the use of an RNAscope™ proprietary antigen retrieval enzyme for bone and cartilage tissue.
Results: At P0, Slc14a1 is primarily expressed in round epiphyseal chondrocytes adjacent to the growth plate and throughout the columnar zones at both ends. At P4, expression is more intense at the epiphyseal/columnar chondrocyte boundary of the distal end, while expression remains more diffuse in the proximal columnar zone. At P9, expression is localized to the epiphyseal/columnar zone boundary in the distal growth plate, and it is absent in the proximal end. Slc14a1 also shows progressively greater expression in the marrow cavity of the primary ossification center from P0 to P9.
Conclusion: Slc14a1 is expressed during growth plate formation and becomes more localized to the reserve zone chondrocytes in the distal P9 MT. The pattern of Slc14a1 expression in the reserve zone echoes that of the Pthlh with stronger expression in the growth plate forming end of the MT. While understanding of the role of this gene in bone biology is limited, it is possible that it may be involved in the PTHrP/Ihh feedback loop, suggesting possible implications of Slc14a1 in ossification of the epiphysis.