Blanche Capel

Overview:

In mammals, the primary step in male sex determination is the initiation of testis development in the bipotential gonad primordium. This step depends on the Y-linked male sex-determining gene, Sry. Expression of Sry in the XY gonad, or as a transgene in an XX gonad, leads to the differentiation of Sertoli cells. Failures in Sertoli cell differentiation in the XY gonad result in sex reversal and ovary formation. In addition to Sertoli cell differentiation, we are studying the signaling pathways between Sry expression and early steps in testis organogenesis using mouse as a model system. Using genetic and cell biology approaches, we determined the origin of several key cell types of the testis. We also identified two pathways, proliferation and cell migration, that are controlled by Sry and lead to the architectural patterning of the testis. Currently we are investigating the novel hypothesis that reciprocal signals between the vasculature and Sertoli cells are involved in patterning testis cords. Testis organogenesis is an ideal model system to study the integration of vasculature during development of organ structure. In addition, we are investigating critical signals between Sertoli cells and germ cells during testis cord formation. Defects in these signals result in teratomas and gonadal blastomas, common neoplasias in young boys. Experimental approaches include the use of molecular and biochemical techniques, mutant mice, transgenics, organ culture assays, differential screens, immunocytochemistry imaging techniques, and classic mouse genetics.

Positions:

James B. Duke Distinguished Professor of Cell Biology

Cell Biology
School of Medicine

Professor of Cell Biology

Cell Biology
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Affiliate of the Regeneration Next Initiative

Regeneration Next Initiative
School of Medicine

Education:

Ph.D. 1989

University of Pennsylvania

Grants:

Identification of a Genetic Pathway Linking Temperature with Epigenetic Control of Gonad Determination in T. scripta

Administered By
Cell Biology
Awarded By
National Science Foundation
Role
Principal Investigator
Start Date
End Date

Defining Mechanisms of Ovarian Rescue

Administered By
Cell Biology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Opposing Pathways in Mammalian Sex Determination

Administered By
Cell Biology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Opposing Pathways in Mammalian Sex Determination

Administered By
Cell Biology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

DND1 Mediated Posttranscriptional Regulation in Murine Prospermatogonia During G1/G0 Arrest

Administered By
Cell Biology
Awarded By
National Institutes of Health
Role
Principal Investigator
Start Date
End Date

Publications:

RUNX1 maintains the identity of the fetal ovary through an interplay with FOXL2.

Sex determination of the gonads begins with fate specification of gonadal supporting cells into either ovarian pre-granulosa cells or testicular Sertoli cells. This fate specification hinges on a balance of transcriptional control. Here we report that expression of the transcription factor RUNX1 is enriched in the fetal ovary in rainbow trout, turtle, mouse, goat, and human. In the mouse, RUNX1 marks the supporting cell lineage and becomes pre-granulosa cell-specific as the gonads differentiate. RUNX1 plays complementary/redundant roles with FOXL2 to maintain fetal granulosa cell identity and combined loss of RUNX1 and FOXL2 results in masculinization of fetal ovaries. At the chromatin level, RUNX1 occupancy overlaps partially with FOXL2 occupancy in the fetal ovary, suggesting that RUNX1 and FOXL2 target common sets of genes. These findings identify RUNX1, with an ovary-biased expression pattern conserved across species, as a regulator in securing the identity of ovarian-supporting cells and the ovary.
Authors
Nicol, B; Grimm, SA; Chalmel, F; Lecluze, E; Pannetier, M; Pailhoux, E; Dupin-De-Beyssat, E; Guiguen, Y; Capel, B; Yao, HH-C
MLA Citation
Nicol, Barbara, et al. “RUNX1 maintains the identity of the fetal ovary through an interplay with FOXL2..” Nat Commun, vol. 10, no. 1, Nov. 2019. Pubmed, doi:10.1038/s41467-019-13060-1.
URI
https://scholars.duke.edu/individual/pub1421630
PMID
31712577
Source
pubmed
Published In
Nature Communications
Volume
10
Published Date
Start Page
5116
DOI
10.1038/s41467-019-13060-1

To Be or Not To Be a Testis.

Work that established the testis as the driver of male development, and the Y-chromosome as the bearer of the male-determining gene, established a working model, and set the stage for the molecular age of mammalian sex determination. The discovery and characterization of Sry/SRY at the top of the hierarchy in mammals launched the field in two major directions. The first was to identify the downstream transcription factors and other molecular players that drive the bifurcation of Sertoli and granulosa cell differentiation. The second major direction was to understand organogenesis of the early bipotential gonad, and how divergence of its two distinct morphogenetic pathways (testis and ovary) is regulated at the cellular level. This review will summarize the early discoveries soon after Sry was identified, and focus on my study of the gonad as a model of organogenesis.
Authors
MLA Citation
Capel, Blanche. “To Be or Not To Be a Testis..” Reproduction, July 2019. Pubmed, doi:10.1530/REP-19-0151.
URI
https://scholars.duke.edu/individual/pub1396204
PMID
31265995
Source
pubmed
Published In
Reproduction
Published Date
DOI
10.1530/REP-19-0151

The RNA-binding protein DND1 acts sequentially as a negative regulator of pluripotency and a positive regulator of epigenetic modifiers required for germ cell reprogramming.

The adult spermatogonial stem cell population arises from pluripotent primordial germ cells (PGCs) that enter the fetal testis around embryonic day (E)10.5. PGCs undergo rapid mitotic proliferation, then enter prolonged cell cycle arrest (G1/G0), during which they transition to pro-spermatogonia. In mice homozygous for the Ter mutation in the RNA-binding protein Dnd1 (Dnd1Ter/Ter ), many male germ cells (MGCs) fail to enter G1/G0 and instead form teratomas: tumors containing many embryonic cell types. To investigate the origin of these tumors, we sequenced the MGC transcriptome in Dnd1Ter/Ter mutants at E12.5, E13.5 and E14.5, immediately prior to teratoma formation, and correlated this information with DO-RIP-Seq-identified DND1 direct targets. Consistent with previous results, we found DND1 controls downregulation of many genes associated with pluripotency and active cell cycle, including mTor, Hippo and Bmp/Nodal signaling pathway elements. However, DND1 targets also include genes associated with male differentiation, including a large group of chromatin regulators activated in wild-type but not mutant MGCs during the E13.5 and E14.5 transition. Results suggest multiple DND1 functions and link DND1 to initiation of epigenetic modifications in MGCs.
Authors
Ruthig, VA; Friedersdorf, MB; Garness, JA; Munger, SC; Bunce, C; Keene, JD; Capel, B
MLA Citation
URI
https://scholars.duke.edu/individual/pub1395666
PMID
31253634
Source
pubmed
Published In
Development
Volume
146
Published Date
DOI
10.1242/dev.175950

Development of germ cells in the mouse.

In mammals, germ cells are induced from a population of cells at the base of the allantois. This regulative mechanism of germ line induction depends on Bmp signals and a combination of epigenetic changes that silence somatic differentiation genes and activate pluripotency genes. RNA binding proteins are a conserved feature of germ cell development in mammals, and play critical roles in the establishment and maintenance of pluripotency. After their specification, germ cells move through the gut to the gonads under the influence of migratory and attractive cues. In the gonad, germ cells initiate sex-specific differentiation. Germ cells that arrive in the ovary enter meiosis, whereas germ cells that arrive in the testis undergo mitotic arrest. Entry into meiosis is controlled by retinoic acid signals that are blocked in the testis. The signals regulating mitotic arrest in the testis are still not completely understood, but likely involve RNA-binding proteins. Epigenetic reprograming occurs during specification, migratory stages, and sex-specific stages, when maternal and paternal imprints are established. The facility of transitions between germ cells and stem cells suggests a close relationship among their genomic programs.
Authors
Durcova-Hills, G; Capel, B
MLA Citation
Durcova-Hills, Gabriela, and Blanche Capel. “Development of germ cells in the mouse..” Curr Top Dev Biol, vol. 83, 2008, pp. 185–212. Pubmed, doi:10.1016/S0070-2153(08)00406-7.
URI
https://scholars.duke.edu/individual/pub868596
PMID
19118667
Source
pubmed
Published In
Current Topics in Developmental Biology
Volume
83
Published Date
Start Page
185
End Page
212
DOI
10.1016/S0070-2153(08)00406-7

A timecourse analysis of systemic and gonadal effects of temperature on sexual development of the red-eared slider turtle Trachemys scripta elegans.

Temperature dependent sex determination (TSD) is the process by which the environmental temperature experienced during embryogenesis influences the sex of an organism, as in the red-eared slider turtle Trachemys scripta elegans. In accord with current paradigms of vertebrate sex determination, temperature is believed to exert its effects on sexual development in T. scripta entirely within the middle third of development, when the gonad is forming. However, whether temperature regulates the transcriptome in T. scripta early embryos in a manner that could influence secondary sex characteristics or establish a pro-male or pro-female environment has not been investigated. In addition, apart from a handful of candidate genes, very little is known about potential similarities between the expression cascade during TSD and the genetic cascade that drives mammalian sex determination. Here, we conducted an unbiased transcriptome-wide analysis of the effects of male- and female-promoting temperatures on the turtle embryo prior to gonad formation, and on the gonad during the temperature sensitive period. We found sexually dimorphic expression reflecting differences in steroidogenic enzymes and brain development prior to gonad formation. Within the gonad, we mapped a cascade of differential expression similar to the genetic cascade established in mammals. Using a Hidden Markov Model based clustering approach, we identified groups of genes that show heterochronic shifts between M. musculus and T. scripta. We propose a model in which multiple factors influenced by temperature accumulate during early gonadogenesis, and converge on the antagonistic regulation of aromatase to canalize sex determination near the end of the temperature sensitive window of development.
Authors
Czerwinski, M; Natarajan, A; Barske, L; Looger, LL; Capel, B
MLA Citation
Czerwinski, Michael, et al. “A timecourse analysis of systemic and gonadal effects of temperature on sexual development of the red-eared slider turtle Trachemys scripta elegans..” Dev Biol, vol. 420, no. 1, Dec. 2016, pp. 166–77. Pubmed, doi:10.1016/j.ydbio.2016.09.018.
URI
https://scholars.duke.edu/individual/pub1146713
PMID
27671871
Source
pubmed
Published In
Dev Biol
Volume
420
Published Date
Start Page
166
End Page
177
DOI
10.1016/j.ydbio.2016.09.018