Russell V. Anthony, PhD
Hill Professor of Biotechnology
Office: W135 ARBL Building, Foothills Campus
My teaching responsibilities primarily lie in graduate education. I currently coordinate and teach Metabolic Endocrinology (BS 632), coordinate and teach the endocrinology and gastrointestinal physiology sections within Mammalian Physiology II (BS 501), and lecture in Reproductive Physiology and Endocrinology (BS640).
The placenta is a multifaceted organ that plays critical roles in maintaining and protecting the developing fetus. These roles include nutrient transfer from the mother to the fetus and waste secretion from the fetus to the mother, acting as a barrier for the fetus against pathogens and the maternal immune system, and as an active endocrine organ. My research is directed at characterizing the communication between the developing fetus and the utero-placental unit that is required for normal fetal growth and development to occur. I hold a joint appointment in the Department of Pediatrics at the University of Colorado Health Sciences Center (UCHSC) in Denver. My research efforts at the Perinatal Research Facility at UCHSC and the Animal Reproduction and Biotechnology Laboratory at CSU provide an integrated research effort in placental and fetal physiology. The following highlight focus areas of our current research.
Transcriptional Regulation and Function of Placental Hormones
As an active endocrine organ, the placenta is capable of secreting a plethora of hormones, growth factors and cytokines. Some of these are true placental hormones since they are not produced by other organs and have known or inferred functions during pregnancy. Included in this category are members of the growth hormone (GH) - prolactin (PRL) gene family. Placental members of this family have been implicated in modulating maternal and fetal metabolism, luteal function and mammogenesis. We have characterized the biosynthesis and structure of one member of this family, ovine placental lactogen (oPL), and have structurally characterized the gene encoding oPL. The 5'-flanking region of the oPL gene is being examined to determine what cis-acting elements and trans-acting factors are responsible for its expression only by chorionic binucleate cells. We now know that this regulation involves a splice variant of activator protein-2a, GATA-2 and PURa, a single-strand DNA binding protein that is involved in the transcriptional regulation of genes expressed in the nervous system. The greatest amount of transactivation is conferred by the sequence residing between -383 to -217 base pairs, relative to the transcriptional start site. This region includes two DNase footprints, FP5 and FP6, mutation of which results the reduction of transactivation to basal levels. While potential Ets-1 and CEBPa cis-acting elements reside in FP6, recent evidence from electrophoretic mobility shift assays, super-shift assays, two-base pair transversion mutations, overexpression studies and RNA interference studies (see figure below) indicates that specificity proteins (Sp) 1 or 3 are responsible for this activity.
Periattachment factor (PAF) is a newly described gene with 10.6-fold higher mRNA concentration in day 17.5 bovine embryos, than in day 15.5 embryos, and its expression declines to non-detectable amounts by day 30 of gestation. This time period is a critical window of ruminant embryo development, and we now know that PAF is expressed at comparable times in pig, sheep and horse embryos, as well as human placenta, kidney and lung in a variety of species. The protein encoded by PAF mRNA contains a nuclear-targeting sequence and 4 protein kinase C phosphorylation sites, but no obvious DNA binding motif. Accordingly, we have hypothesized that PAF may be acting as a coactivator/corepressor of transcription during this critical window of conceptus development. We have generated recombinant PAF and are in the process of generating antibodies raised against PAF, as well as developing short hairpin RNA (shRNA) cassettes for use in RNA interference to examine the function of PAF. Our approach is to use lentivirus-mediated stable transfection (see figure below) of sheep embryos, to effectively "knockdown" PAF activity during this window of conceptus development, and determine the effects on conceptus development and pregnancy maintenance.
Placental Function and Fetal Development
Placental insufficiency-fetal growth restriction (PI-FGR) is a major cause of increased perinatal morbidity and mortality in humans, and has recently been tied to the predisposition of adult onset of diabetes, hypertension, stroke and coronary heart disease. Using a pregnant sheep model of PI-FGR, we are studying the vascular and endocrine development of the placenta in PI-FGR pregnancies. The overall aim of these studies is to determine what aspects of placental development are insufficient or incorrect, thereby setting the stage for an FGR outcome. It is our hope that, through these basic studies, key developmental mechanisms can be evaluated, such that potential interventive methods can be derived.We have determined that placental vascular structure is altered, and that expression of vascular endothelial growth factor and placental growth factor, their receptors VEGFR1 and VEGFR2, antiopoietin 1 and angiopoietin 2, and their common receptor Tie 2, is altered at varying times during FGR pregnancies. Collectively these data infer that there are acute responses and more chronic responses or changes in the factors driving placental vasculogenesis and angiogenesis in FGR pregnancies. Furthermore, maternal concentrations of progesterone and oPL are depressed in PI-FGR pregnancies, and during late gestation the FGR placenta truly has a deficit in its ability to produce progesterone. Near-term these fetuses become hypoxic, hypoglycemic and hypertensive, as a result of the altered placental development and functional placental insufficiency, as evidenced in the changes in fetal oxygenation depicted below.
Due to the role that fetal hypoxia may play in altered fetal development within FGR pregnancies, and the impact that this may have on postnatal well being, we are examining the impact of development stage-specific prenatal hypoxia in rats. Initially we predicted that prenatal hypoxia from days 18 through 21 of gestation in rats would have the greatest detrimental effects, but have found more interesting results following prenatal hypoxia at days 12 through 15. As a result of this early hypoxia, the rats are smaller at birth, but at postnatal day 30 these rats are hyperinsulinemic, have reduced liver glycogen stores and reduced liver glycogen synthase. These preliminary results may indicate that early prenatal hypoxia-induced developmental programming may induce adolescent insulin resistance, potentially resulting in type 2 Diabetes. We continue to examine this rat model as a means of determining the long-term impact of altered fetal environment.
Regnault TRH, Battaglia FC, Wilkening RB, Anthony RV. 1999. Altered arterial concentrations of placental hormones during maximal placental growth in a model of placental insufficiency. J Endocrinol 163:433-442.
Liang R, Limesand SW, Anthony RV. 1999. Structure and transcriptional regulation of the ovine placental lactogen gene. Eur J Biochem 265:883-895.
Phillips ID, Anthony RV, Owens JA, Robinson JS, McMillen IC. 2001. Restriction of fetal growth has a differential impact on fetal prolactin and prolactin receptor mRNA expression. J Neuroendocrinol 13:175-181.
Limesand SW, Anthony RV. 2001. Novel activator protein-2a splice-variants function as transactivators of the ovine placental lactogen gene. Eur J Biochem 268:2390-2401.
Devaskar SU, Anthony R, Hay W Jr. 2002. Ontogeny and insulin regulation of fetal ovine white adipose tissue leptin expression. Am J Physiol 282:R431-R438.
Regnault TRH, Galan HL, Parker TA, Anthony RV. 2002. Placental development in normal and compromised pregnancies. Placenta 23:S119-S129.
Regnault TRH, Orbus RJ, de Vrijer B, Davidsen M, Limesand SW, Galan HL, Wilkening RB, Anthony RV. 2002. Placental expression of VEGF, PIGF and their receptors in a model of placental insufficiency-intrauterine growth restriction (PI-IUGR). Placenta 23:132-144.
Anthony RV, Scheaffer AN, Wright CD, Regnault TRH. 2003. Ruminant models of prenatal growth restriction. Reproduction Suppl 61:183-194.
Regnault TRH, DeVrijer B, Galan HL, Davidsen ML, Trembler KA, Battaglia FC, Wilkening RB, Anthony RV. 2003. The relationship between transplacental O2 diffusion and placental expression of PlGF, VEGF and their receptors in a placental insufficiency model of fetal growth restriction. J Physiol 550:641-656.
Limesand SW, Jeckel KM, Anthony RV. 2004. Pura, a single-stranded DNA binding protein, augments placental lacogen gene transcription. Mol Endocrinol 18:447-457.
Galan HL, Anthony RV, Rigano S, Parker TA, de Vrijer B, Ferrazzi E, Wilkening RB, Regnault TRH. 2005. Hypertension and abnormal doppler velocimetry in the growth restricted fetus. Am J Obstet Gynecol 192:272-279.
Wallace JM, Regnault TRH, Limesand SW, Hay WW Jr, Anthony RV. 2005. Investigating the causes of low birth weight in contrasting ovine paradigms. J Physiol 565:19-26.
Erickson Hagen AS, Orbus RJ, Wilkening RB, Regnault TRH, Anthony RV. 2005. Placental expression of angiopoietin-1, angiopoietin-2 and Tie-2 during placental development in an ovine model of placental insufficiency-fetal growth restriction. Ped Res 58:1228-1232.
Arroyo JA, Anthony RV, Parker TA, Galan HL. 2006. Differential expression of placental and vascular endothelial nitric oxide Synthase (eNOS) in an ovine model of fetal growth restriction. Am J Obstet Gynecol 195:771-777.
de Vrijer B, Davidsen ML, Wilkening RB, Anthony RV, Regnault TRH. 2006. Altered placental and fetal expression of IGFs and IGF-binding proteins associated with intrauterine growth restriction in fetal sheep during early and mid pregnancy. Ped Res 60: in press.