Joomyeong ‘Joo’ Kim
Russell Thompson, Jr. Family Professor
BMB Division
PhD: Louisiana State University Medical Center at New Orleans, 1995
Phone: 225-578-7692
Office: 644 Life Sciences Building
Lab: 686/688 Life Sciences Building
E-mail: jkim@lsu.edu
Area of Interest
Genomic imprinting and Epigenetics
Genomic imprinting is an epigenetic mechanism in which only one allele of a gene is expressed while the other is silenced through DNA methylation and histone modifications. In mammalian genomes, approximately 200 autosomal genes are regulated in this parent-of-origin–specific manner. Imprinting is found primarily in eutherian mammals and is thought to have co-evolved with their unique reproductive strategies involving placentation and viviparity. Our laboratory has characterized one such imprinted region located on human chromosome 19q13.4 and the syntenic region on proximal mouse chromosome 7. This 500-kb domain contains seven imprinted genes—paternally expressed Peg3, Usp29, Zfp264, and APeg3, and maternally expressed Zim1, Zim2, and Zim3.
This domain is regulated by two cis-acting elements: the oocyte-specific alternative promoter U1 and the Peg3 Differentially Methylated Region (Peg3-DMR). The U1 promoter establishes maternal-specific DNA methylation at the Peg3-DMR, which in turn drives paternal expression of Peg3 and Usp29 and maternal expression of Zim1. Comparative genomic analyses suggest that the U1 promoter originated from an ancient retrotransposon that inserted before the radiation of mammalian species. Deletion of this promoter leads to biallelic expression—and thus a two-fold dosage—of Peg3, resulting in several reproduction-related phenotypes, including delayed parturition and impaired placentophagy (placenta-eating) and nest-building behaviors. Currently, our research focuses on two major questions regarding the Peg3 imprinted domain: (1) how retrotransposons contributed to the formation of this domain during mammalian evolution, and (2) what roles this domain plays in mammalian reproduction.
Selected Publicationscomplete list of publications
Publications (2025)
Kim J. (2025) Ancient retrotransposon-derived promoters for mammalian genomic imprinting. https://doi.org/10.1101/2025.07.14.664778.
Kim J. (2025) Fetal influence on maternal pregnancy through the Peg3 imprinted domain (submitted).