New Gene Family Discovered
Researchers at the University of Texas Southwestern Medical Center (Dallas, TX) discovered a gene family that may play an essential role in cell division in a variety of cell types. Their finding, reported in the July issue of Human Molecular Genetics, may lead to breakthroughs in the treatment of male infertility and cancer.
The group, led by Andrew Zinn, assistant professor of internal medicine, was on the trail of a gene called morc, which they knew to be essential for spermatogenesis (morc is short for microrchidia, a medical term for abnormally small testes). After isolating the gene from mice and humans, they found the protein, or similar ones, not only in the testis, but also in other tissues in all the multi-cellular organisms tested, including zebrafish, nematodes, slime mold, and plants.
"Morc is apparently part of a novel pathway that regulates sperm production," said Zinn. "Possibly even more important is that, because we have found similar human proteins in many tissues, we believe morc defines a new gene family that plays an as yet unknown, important function in all cells."
Prior work from Zinn's group in collaboration with Mark Watson, assistant professor of pathology, on a transgenic mouse bearing the morc mutation had shown that it prevents sperm maturation by blocking the earliest stages of sperm production. Mice are normal at birth, but at puberty (day 10) precursor cells for sperm production began dying through apoptosis. This scenario resembles some types of male infertility in humans. In addition, since some testicular tumors are believed to arise from germ cells blocked in sperm production, morc also may play a role in tumorigenesis.
Because the researchers know how the mutation affects male reproduction and they have now found Morc in other cell types, they believe that other family members may perform a similar function in cell division in somatic cells, or mitosis, as Morc does in meiosis.
"Morc family members may serve a general role in the regulation of cell division in all tissues and may malfunction in cancer cells," Watson said. "The next step is to discover with which proteins Morc interacts in the nucleus. This will give us clues as to its biochemical function."
The other researchers involved in the study were: Norimitsu Inoue, a postdoctoral fellow in the Eugene McDermott Center for Human Growth and Development; former UT Southwestern pathology research assistant Karl Hess; and Randall Moreadith, formerly of the UT Southwestern Department of Internal Medicine. Researchers at the University of Tennessee (Knoxville) also participated in the study.
For more information: Andrew Zinn, Eugene McDermott Center for Human Growth and Development, UT Southwestern Medical Center at Dallas, Dallas, TX, 75235-9094. Tel: 214-648-1615. Fax: 214-648-1666. Email: Andrew.Zinn@email.swmed.edu.