This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Vallette-Kasic, S. Articles by Drouin, J. Search for Related Content PubMed PubMed Citation Articles by Vallette-Kasic, S. Articles by Drouin, J. Related Collections Neuroendocrinology and Pituitary Pediatric Endocrinology

The TPIT Gene Mutation M86R Associated with Isolated Adrenocorticotropin Deficiency Interferes with Protein: Protein Interactions

Laboratoire de Génétique Moléculaire (S.V.-K., C.C., A.B., Y.G., J.D.), Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada H2W 1R7; Molecular Endocrinology (L.M.), William Harvey Research Institute, London EC1M 6BQ, United Kingdom; and Developmental Endocrinology Research Group (M.D.), Clinical and Molecular Genetics Unit, Institute of Child Health London, University College London, London, WC1N 1EH, United Kingdom

Address all correspondence and requests for reprints to: Dr. Jacques Drouin, Laboratoire de génétique moléculaire, Institut de recherches cliniques de Montréal, 110, avenue des Pins Ouest, Montréal, QC, Canada H2W 1R7. E-mail: jacques.drouin{at}ircm.qc.ca.

Context: Tpit is a T-box transcription factor important for terminal differentiation of pituitary proopiomelanocortin-expressing cells. We previously showed that human and murine mutations in the gene encoding this highly cortico/melanotrope-specific transcription factor cause a neonatal onset form of congenital isolated ACTH deficiency (IAD). We characterized the largest series of neonatal IAD patients caused by TPIT mutations, and this revealed a highly homogeneous clinical presentation. So far, 12 different loss-of-function TPIT mutations have been identified. The methionine 86 arginine (M86R) TPIT mutation was recently identified in compound heterozygosity with the 782delA frame-shift mutation in two siblings with early-onset IAD.

Objective: We conducted a functional analysis of the missense M86R mutation to assess transcriptional activity, DNA binding activity, and nuclear location, as well as protein-protein interactions.

Results: Although the M86 residue is located within the T-box DNA-binding domain, it did not affect monomer DNA-binding activity per se, but it impaired DNA binding with other DNA-bound proteins, including itself (homodimers) and pituitary homeobox 1 (Pitx1). The M86 residue is at the interface between T domains in the T dimers crystal structure, and it appears that the same residue is involved in heterodimer formation with pituitary Pitx1. Furthermore, TPIT M86R is deficient in the recruitment of the coactivator SRC2 that partly mediates the CRH stimulation of proopiomelanocortin transcription.

Conclusion: Thus, the M86R TPIT mutation is defining an important surface of the T domain for multiple protein interactions and for transcription.

This article has been cited by other articles:

				S. A. Miller, A. C. Huang, M. M. Miazgowicz, M. M. Brassil, and A. S. Weinmann Coordinated but physically separable interaction with H3K27-demethylase and H3K4-methyltransferase activities are required for T-box protein-mediated activation of developmental gene expression Genes & Dev., November 1, 2008; 22(21): 2980 - 2993. [Abstract] [Full Text] [PDF]

				P.-L. Lavoie, L. Budry, A. Balsalobre, and J. Drouin Developmental Dependence on NurRE and EboxNeuro for Expression of Pituitary Proopiomelanocortin Mol. Endocrinol., July 1, 2008; 22(7): 1647 - 1657. [Abstract] [Full Text] [PDF]