Yugong Ho, Ph.D.
1999, Ph.D., Temple University
Current Research
A set of distal human growth hormone (hGH) cluster locus control regions (LCR), identified initially by their DNase I hypersensitivity (HS), have been shown to be essential for the tissue-restricted expression of hGH gene. A 1.6 kb fragment of the LCR containing only HS I,II is sufficient to confer a high-level of hGH-N expression in pituitaries of transgenic mice when the fragment is juxtaposed to the hGH gene.

One of my projects is to study the cis-acting HS I,II in the context of the intact hGH locus. A bacteriophage P1-clone containing the majority of the hGH cluster and the full set of the LCR is identified in this lab. I am using RecA-assisted homologous recombination to mutate the HS I, II region in the P1 clone. The expression of the hGH will be studied in transgenic mice carrying the mutated LCR and hGH cluster to characterize the role(s) of the HS I,II in tissue-specific expression of the hGH. The minimum sequence required for the HS I,II cis-acting activity will be identified using this approach. I am also going to determine whether HS I,II acts as the sole determinant of somatotrope specificity of hGH by deleting the HS I,II region using the same approach.

The second project I am interested is to study whether hGH LCR is conserved in the mouse growth hormone (mGH) gene. Our hypothesis is that sequence- and functional-homologues of the hGH LCR have been evolutionarily preserved in the mouse genome. P1 clones containing the mGH and 5'-flanking region of the mGH are identified. The sequence homologous to the hGH LCR in the mGH 5'-flanking region will be identified. DNase I mapping will be performed in the DNA of the mGH ant 5'-flanking region in intact chromatin isolated from pituitaries of mouse line expresses high-level GH to investigate whether the sequence homologous to hGH LCR is DNase I hypersensitive. Any additional HS site in mGH locus will also be identified using this approach. These HS sites will be deleted from the mouse genome and the expression of mGH will be studied to characterize the role(s) of these HS sites.

Selected Publications
  1. Ho, Y., Doherty, A.S. and Schultz, R.M. (1994). Mouse preimplantation embryo development in vitro: effect of sodium concentration an culture media on RNA synthesis and accumulation and gene expression. Mol. Repro. and Dev., 38, 131-141

  2. Ho, Y., Wigglesworth, K., Eppig, J.J. and Schultz, R.M. (1995) Preimplantation development of mouse embryo in KSOM: augmentation by amino acid and analysis of gene expression. Mol. Repro. and Dev., 41,232-238.

  3. Ho, Y., Kim, S and Waring R.B. (1997) A protein encoded by a group I intron directly assists RNA splicing and is a DNA endonuclease. Proc. Natl. Acad. Sci.USA, 94, 8994-8999.

  4. Ho, Y., and Waring R.B. (1999). The maturase encoded by a group I intron from Aspergillus nidulans stabilizes RNA tertiary structure and promotes rapid splicing. J.Mol.Biol., 292,987-1001.

  5. Ho, Y., Elefant, F., Cooke, N.E. and Liebhaber, S.A. (2001). A Defined Locus Control Region Determinant Mediates Chromatin Domain Acetylation and Remote Gene Activation. Submitted.
Last Updated: Thu, May 17, 2001