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. Author manuscript; available in PMC: 2025 Oct 31.
Published in final edited form as: Am J Physiol Endocrinol Metab. 2025 Sep 12;329(5):E707–E718. doi: 10.1152/ajpendo.00084.2025

Figure 6. Effects of low dose ACTH1–24 on structural bone proteins, the ACTH1–24 and VEGF receptors, and mitochondrial complex proteins of human osteoblasts.

Figure 6.

Human osteoblasts were differentiated for 5 weeks on polyethylene terephthalate membranes as described in Methods. Effects of no ACTH1–24 to 10−12 M, 10−9 M, and 10−6 M ACTH1–24 treatment by PCR. For clarity, p-values are shown in the figure only.

A. Effect on structural proteins and key bone differentiation factors. Individual PCR measurements of type I collagen (Col1A1), bone GLA protein (osteocalcin), alkaline phosphatase (ALPL), and the master differentiation factor RunX2 are shown. Significant effects are seen for all, with maximal effects for collagen and alkaline phosphatase at 10−12 M.

B. Effect on the ACTH1–24 receptor MC2R and on the key differentiation cytokine VEGF and its receptors FLT-1 and FLK-1. Effects are variable but seen at 10−12 M for the MC2R, VEGF, and FLK-1. Effects on FLT-1 are smaller and less distinct.

C. Variable effects on several mitochondrial complex proteins. This was studied because of the energy-intensive process of bone formation. All were upregulated at 10−12M ACTH1–24, but with variable effects and variable specificity for the lowest dose of ACTH1–24.