Jun-li Liu

Biography

Peking University, China BSc 1978-1982 Biology Peking University, Health Science Centre, China MSc 1982-1985 Physiology McGill University, Montreal, Canada PhD 1990-1995 Experimental Medicine National Institutes of Health, NIDDK, Bethesda, MD Postdoctoral 1995-2000 Endocrinology

Research Interest

Insulin-like growth factor (IGF)-I is a peptide hormone mainly produced from the liver and other tissues at lower and variable levels. Research of last decade by us and others has established that IGF-I is a potent growth factor for pancreatic islet cells, promotes cell survival and prevents onset of experimental diabetes. In order to explore where and how IGF-I acts on the islet cells, we have screened and identified the molecular targets using the technique of whole genome microarray. Prominently among the 82 preliminary targets we have discovered, CCN5/WISP2 has never been known to be expressed by the islet cells nor regulated by IGF-I. In a recent study we have shown that CCN5 is normally expressed in islet beta-cells, IGF-I directly stimulates its gene expression, and IGF-I overexpression caused increased level in the islets. We further demonstrate CCN5 overexpression accelerates the proliferation of insulinoma cells, activate signaling molecules Akt and/or Erk1/2 kinases, and CCN5 overexpression prevent cell death. We thus hypothesize that CCN5 is normally expressed by islet beta-cells and activated by IGF-I, its increased production promote islet cell proliferation and regeneration, and survival, in concert to the action of IGF-I. We propose to establish a direct stimulation of CCN5 gene expression by IGF-I, the effects of in vitro administration of CCN5 on pancreatic islet cell proliferation and survival against harsh conditions, in vivo stimulation on pancreatic islet regeneration after removing part of the pancreas, and in vivo protection of CCN5 protein against experimental diabetes in mice. These studies will aid in the design of novel and potentially more effective therapeutic approaches exploiting CCN5 and its molecular targets, in improving the survival and function of the pancreatic islet cells.