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Paired related homeobox 1 is a protein that in humans is encoded by the PRRX1 gene.[1][2]


The DNA-associated protein encoded by this gene is a member of the paired family of homeobox proteins localized to the nucleus. The protein functions as a transcription coactivator, enhancing the DNA-binding activity of serum response factor, a protein required for the induction of genes by growth and differentiation factors. The protein regulates muscle creatine kinase, indicating a role in the establishment of diverse mesodermal muscle types. Alternative splicing yields two isoforms that differ in abundance and expression patterns.[2]

Role in mesenchymal stem cell differentiation

Prrx1 expression is restricted to the mesoderm during embryonic development, and both Prrx1 and Prrx2 are expressed in mesenchymal tissues in adult mice.[3][4][5][6][7] Mice that lack both Prrx1 and Prrx2 have profound defects in mesenchymal cell differentiation in the craniofacial region.[5][8] Several recent studies demonstrate that PRRX1 can regulate differentiation of mesenchymal precursors. For example, PRRX1 inhibits adipogenesis by activating transforming growth factor-beta (TGF-beta) signaling,[9] and also acts downstream of tumor necrosis factor-alpha to inhibit osteoblast differentiation.[10]


  1. Grueneberg DA, Natesan S, Alexandre C, Gilman MZ (Sep 1992). "Human and Drosophila homeodomain proteins that enhance the DNA-binding activity of serum response factor". Science. 257 (5073): 1089–95. doi:10.1126/science.257.5073.1089. PMID 1509260.
  2. 2.0 2.1 "Entrez Gene: PRRX1 paired related homeobox 1".
  3. Kern MJ, Witte DP, Valerius MT, Aronow BJ, Potter SS (October 1992). "A novel murine homeobox gene isolated by a tissue specific PCR cloning strategy". Nucleic Acids Res. 20 (19): 5189–95. doi:10.1093/nar/20.19.5189. PMC 334304. PMID 1383943.
  4. Nohno T, Koyama E, Myokai F, Taniguchi S, Ohuchi H, Saito T, Noji S (July 1993). "A chicken homeobox gene related to Drosophila paired is predominantly expressed in the developing limb". Dev. Biol. 158 (1): 254–64. doi:10.1006/dbio.1993.1184. PMID 8101172.
  5. 5.0 5.1 Lu MF, Cheng HT, Kern MJ, Potter SS, Tran B, Diekwisch TG, Martin JF (February 1999). "prx-1 functions cooperatively with another paired-related homeobox gene, prx-2, to maintain cell fates within the craniofacial mesenchyme" (PDF). Development. 126 (3): 495–504. PMID 9876178.
  6. Hu YS, Zhou H, Kartsogiannis V, Eisman JA, Martin TJ, Ng KW (November 1998). "Expression of rat homeobox gene, rHOX, in developing and adult tissues in mice and regulation of its mRNA expression in osteoblasts by bone morphogenetic protein 2 and parathyroid hormone-related protein". Mol. Endocrinol. 12 (11): 1721–32. doi:10.1210/me.12.11.1721. PMID 9817598.
  7. Cserjesi P, Lilly B, Bryson L, Wang Y, Sassoon DA, Olson EN (August 1992). "MHox: a mesodermally restricted homeodomain protein that binds an essential site in the muscle creatine kinase enhancer". Development. 115 (4): 1087–101. PMID 1360403.
  8. ten Berge D, Brouwer A, Korving J, Martin JF, Meijlink F (October 1998). "Prx1 and Prx2 in skeletogenesis: roles in the craniofacial region, inner ear and limbs". Development. 125 (19): 3831–42. PMID 9729491.
  9. Du B, Cawthorn WP, Su A, Doucette CR, Yao Y, Hemati N, Kampert S, McCoin C, Broome DT, Rosen CJ, Yang G, MacDougald OA (February 2013). "The transcription factor paired-related homeobox 1 (Prrx1) inhibits adipogenesis by activating transforming growth factor-β (TGFβ) signaling". J. Biol. Chem. 288 (5): 3036–47. doi:10.1074/jbc.M112.440370. PMC 3561528. PMID 23250756.
  10. Lu X, Beck GR, Gilbert LC, Camalier CE, Bateman NW, Hood BL, Conrads TP, Kern MJ, You S, Chen H, Nanes MS (January 2011). "Identification of the homeobox protein Prx1 (MHox, Prrx-1) as a regulator of osterix expression and mediator of tumor necrosis factor α action in osteoblast differentiation". J. Bone Miner. Res. 26 (1): 209–19. doi:10.1002/jbmr.203. PMC 3179318. PMID 20683885.

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This article incorporates text from the United States National Library of Medicine, which is in the public domain.