Mediator Kinase Disruption in MED12-Mutant Uterine Fibroids From Hispanic Women of South Texas.
J Clin Endocrinol Metab. 2018 11 01; 103(11):4283-4292.JC

Abstract

Context

Mutations in the gene encoding Mediator complex subunit MED12 are dominant drivers of uterine fibroids (UFs) in women of diverse racial and ethnic origins. Previously, we showed that UF-linked mutations in MED12 disrupt its ability to activate cyclin C-CDK8/19 in Mediator. However, validation of Mediator kinase disruption in the clinically relevant setting of MED12-mutant UFs is currently lacking.

Objective

The objective of this study was twofold. First, to extend the ethnic distribution profile of MED12 mutations by establishing their frequency in UFs from Hispanic women of South Texas. Second, to examine the impact of MED12 mutations on Mediator kinase activity in patient-derived UFs.

Methods

We screened 219 UFs from 76 women, including 170 tumors from 57 Hispanic patients, for MED12 exon 2 mutations, and further examined CDK8/19 activity in Mediator complexes immunoprecipitated from MED12 mutation-negative and MED12 mutation-positive UFs.

Results

MED12 exon 2 mutations in UFs from Hispanic women are somatic in nature, predominantly monoallelic, and occur at high frequency (54.1%). We identified a minimal cyclin C-CDK8 activation domain on MED12 spanning amino acids 15 through 80 that includes all recorded UF-linked mutations in MED12, suggesting that disruption of Mediator kinase activity is a principal biochemical defect arising from these pathogenic alterations. Analysis of Mediator complexes recovered from patient UFs confirmed this, revealing that Mediator kinase activity is selectively impaired in MED12-mutant UFs.

Conclusions

MED12 mutations are important drivers of UF formation in Hispanic women of South Texas. MED12 mutations disrupt Mediator kinase activity, implicating altered CDK8/19 function in UF pathogenesis.

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Authors+Show Affiliations

Park MJ
Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
Shen H
Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
Kim NH
Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
Gao F
Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
Failor C
Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
Knudtson JF
Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
McLaughlin J
Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
Halder SK
Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, Augusta, Georgia.
Heikkinen TA
Research Programs Unit, Genome-Scale Biology Research Program and Medicum, Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
Vahteristo P
Research Programs Unit, Genome-Scale Biology Research Program and Medicum, Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland.
Al-Hendy A
Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, Augusta, Georgia.
Schenken RS
Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
Boyer TG
Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas.

MeSH

AdultCyclin-Dependent Kinase 8Cyclin-Dependent KinasesDNA Mutational AnalysisEnzyme AssaysExonsFemaleHispanic AmericansHumansLeiomyomaMediator ComplexMiddle AgedMutationRecombinant ProteinsTexasUterine NeoplasmsUterus

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

30099503