Postdoctoral Position Available

Charles Sagerstrom, Ph.D.

Academic Role: Associate Professor

Faculty Appointment(s) In:
   Biochemistry and Molecular Pharmacology

Other Affiliation(s):
   Interdisciplinary Graduate Program

Gene expression in embryogenesis

Formation of the vertebrate central nervous system (CNS) begins early during embryogenesis - at gastrula stages, but extensive refinements continue to take place before the fully functional adult CNS emerges. Neural development is carefully controlled and perturbations of this process give rise to defects ranging from severe developmental abnormalities to mild cognitive impairments. We are studying genes that control early neural development, particularly formation of the caudal CNS (hindbrain and spinal cord) in the zebrafish, using a three-step strategy. 

Gene discovery
We are screening for novel genes involved in neural development by several approaches.  First, we have used subtractive hybridization to isolate genes expressed specifically in the caudal CNS. Second, we are using ‘expression profiling’ to identify novel genes expressed downstream of paralog group 1 hox genes in the caudal hindbrain.  Third, we are undertaking a haploid genetic screen for mutations affecting hindbrain development.  Fourth, we are using co-precipitation together with MALDI-TOF analysis to identify interacting partners of proteins known to regulate hindbrain development.

Derive genetic pathways
We next integrate these genes into pathways that drive hindbrain development, using a number of molecular genetic approaches. For instance, we use injection of synthetic mRNA to ectopically activate gene function in wild type embryos, or to rescue defects in various mutant lines, and we use antisense technology to ‘knock-down’ the function of specific genes. We have recently begun generating transgenic lines that will provide better spatiotemporal control for these types of misexpression studies.

Define biochemical activities
Lastly, we define the function of the various gene products using a variety of biochemical approaches.  For instance, we carry out reporter assays in transfected cell lines, analyze protein:protein interactions in vivo and in vitro and study histone acetylation using embryo lysates.

Research Figure

Legend:

Wholemount in situ hybridization detects the expression of four different genes (two in red, two in purple) in the forming neurectoderm of the zebrafish. (Dorsal view at 10 hours post fertilization.)

Recent Publications

C.G. Sagerström, Y. Grinblat and H. Sive. (1996).   Anteroposterior patterning in the zebrafish, Danio rerio: an explant assay reveals inductive and suppressive cell interactions.  Development.122: 1873-1883.

C.G. Sagerström and H.L. Sive. (1996).  RNA blot analysis.  In A laboratory guide toRNA: Isolation, Analysis and Synthesis.   Ed. P. Krieg. Wiley-Liss, Inc. pp 83-103.

C.G. Sagerström, B.I. Sun, and H.L. Sive. (1997). Subtractive hybridization: Past present and future. Ann. Rev. Biochem. 66:751-783.

C.G. Sagerström. (1997) Slippery slopes: Understanding gradients and asymmetries in development.   Trends in Cell Biology  7:463-465.

Y. Grinblat, M. Lane, C.G. Sagerström and H. Sive. (1998). Analysis of zebrafish development using explant culture assays. Meth. Cell Biol. 59:128-155.

N. Vlachakis, D. Ellstrom and C.G. Sagerström. (2000). A novel Pbx family member expressed during early zebrafish embryogenesis forms trimeric complexes with Meis3 and Hoxb1b. Developmental Dynamics 217:109-119.

C.G. Sagerström, B. Kao, M. Lane and H.L. Sive. (2001). Isolation and characterization of posteriorly restricted genes in the zebrafish gastrula. Developmental Dynamics 220:402-408.

N. Vlachakis, S-K. Choe and C. G. Sagerström. (2001). Meis3 synergizes with Pbx4 and Hoxb1b in promoting hindbrain fates in the zebrafish. Development 128:1299-1312.

S.-K. Choe, N. Vlachakis and C. G. Sagerström. (2002). Meis family proteins are required for hindbrain development in the zebrafish. Development 129:585-595.

L. Etheridge, P. diIorio and C. G Sagerström (2002). A zebrafish unc-45 related gene expressed during muscle development. Developmental Dynamics 224:457-460.

M. E. Lane  , A. P. Runko, N. M. Roy, and C. G. Sagerström. (2002). Dynamic expression and regulation by Fgf8 and Pou2 of the zebrafish LIM-only gene lmo4. Mechanisms of Development 119: S185-189.

K. M. Astrofsky, R. A. Bullis and C. G. Sagerström (2002). Biology and management of the zebrafish. In Laboratory Animal Medicine. 2^nd edition.  Ed. J. Fox, L. Anderson, F. Loew, F. Quimby, pp. 861-883. Academic

A. P. Runko and C. G. Sagerström. (2003). Nlz belongs to a family of zinc-finger containing repressors and controls segmental gene expression in the zebrafish hindbrain. Developmental Biology 262:254-267.

N. M. Roy and C. G. Sagerström (2004).  An early Fgf-signal required for gene expression in the zebrafish hindbrain primordium. Developmental Brain Research. 148: 27-42.

A. P. Runko and C. G. Sagerström (2004). Isolation of nlz2 and characterization of essential domains in Nlz-family proteins. Journal of Biological Chemistry 279: 11917-11925.

S. –K. Choe and C. G. Sagerström. (2004).  Paralog group 1 hox genes regulate rhombomere 5/6-expression of vhnf1, a repressor of rostral hindbrain fates, in a meis-dependent manner.  Developmental Biology  271:350-361.

M. Nakamura,  A. P. Runko and C. G. Sagerström. (2004).  A novel zinc-finger subfamily regulating embryogenesis.  Journal of Cellular Biochemistry. 93:887-895

C. G. Sagerström. (2004).   pbX marks the spot.  Developmental Cell 6: 737-738

C. G. Sagerström, L. S. Gammill, R. Veale and H. Sive. (2005).   Specification of the enveloping layer and lack of autoneuralization in zebrafish embryonic explants. Developmental Dynamics 232: 85-97.

S. –K. Choe and C. G. Sagerström. (2005). Variable meis-dependence among paralog group-1 hox genes. Biochemical and Biophysical Research Communications.   331:1384-1391.

Rotation Project Background

During early embryogenesis the primordium of the central nervous system (CNS) consists of an epithelium - the neural plate - that is only a single cell-layer thick. The neural plate subsequently undergoes an extraordinary set of developmental steps to form all structures of the adult CNS. This process raises two separate, but interrelated, questions: 1). How is each neural structure positioned correctly? and 2). How is the differentiation of each structure regulated? We are particularly interested in understanding the earliest steps in these processes and we focus our work on how the caudal CNS (the cerebellum, brainstem and spinal cord) is formed.

We have isolated several genes that are expressed in the neural plate and we use zebrafish embryos to explore the role of these genes in formation of the caudal CNS. We combine in vivo experiments aimed at defining the biological role of each gene with in vitro biochemical experiments aimed at understanding their mechanism of action.

Potential Rotation Projects

1. Role of Pbx4 in controlling histone acetylation.   The Pbx4 transcription factor binds both histone deacetylases (HDACs) and histone acetyltransferases (HATs) in vitro, but it is not clear if these interactions are essential in vivo.  This project entails identifying HDAC and HAT binding sites on Pbx4 and testing binding mutants in cell culture reporter assays as well as in zebrafish embryos.
2. Identification of novel Nlz-interacting proteins.  The Nlz protein acts a repressor of transcription, but appears to require cofactors to access target promoters.  This project entails identifying Nlz-interacting proteins by ‘pull-down’ from zebrafish embryo lysates.
3. Deriving a genetic pathway for the formation of hindbrain rhombomere (r) 4 and 5.  A number of genes are required for formation of r4 and r5, but it is not clear how they fit into a genetic pathway.  This project entails gene misexpression in wild type and mutant zebrafish embryos using mRNA injections and transgenic lines.

Academic Background

B.A., Macalester College, MN, 1987
Ph.D., Stanford University, CA, 1993

Office: LRB-815, Lab 870 D-F
Phone: 508-856-8006
E-mail: Charles.Sagerstrom@umassmed.edu
Keywords: Neurobiology, Gene Expression, Developmental Biology

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Postdoctoral Position Available A postdoctoral position is available to study in this laboratory. Contact Dr. Sagerström for additional details.