Blastocyst Development and Pluripotent Stem Cell Differentiation Biology
Our research group is studying the cellular and molecular biology of mammalian embryonic cell proliferation and cell differentiation. We use experimental systems such as (i) development of blastocyst through hatching process and (ii) differentiation of pluripotent stem cells (PSCs) to tri-lineage cell types i.e., cardiac, neural and pancreatic islet cell aggregate cell types. Questions being addressed are (i) how the first differentiated embryo ( i.e., blastocyst) is formed; (ii) how blastocyst undergoes zona pellucida hatching and how it becomes implantation-competent, leading to establishment of early pregnancy. Blastocyst-derived hatching enabling molecular regulators are examined in terms of their gene expression, sub-cellular localization and function (Fig. 1).
To study differentiation of PSCs, we earlier derived EGFP-transgene-expressing (i) embryonic stem cell line (GS-2 ES-cell line) and (ii) induced pluripotent stem cell (N9 iPS-cell) line. Using these transgenic PSC lines, we are addressing questions related to enrichment and mechanism of differentiation of cardiac, neuronal and pancreatic β-islet cell types. Also, cell signaling mechanisms and differentiation-associated gene expression profiles and their epigenetic regulations are being investigated (Fig. 2).
In the area of reproductive endocrinology, we assess sex-steroid and glucocorticoid hormones and their fecal metabolites in Asian elephants in order to assess reproductive and stress status of free-ranging elephants and possibly endangered primate species (Collaborative project with Prof. R. Sukumar, CES).
We employ a number of state-of-the-art experimental approaches such as culture of embryos/stem cells, cell-molecular biological and immunofluorescence methods, FACS analysis, video-micrograph and morphometric analysis, patch-clamp-based electrophysiological analysis during real embryo development time. These studies contribute to our knowledge on the basic biology of early development and stem cell differentiation. They have implications in animal (human) biotechnology, alleviation of infertility and regenerative medicine.
- Sen Roy S. and Seshagiri P.B. Expression and function of cyclooxygenase-2 is necessary for hamster blastocyst hatching. Mol. Hum. Reprod, 19: 838–851, 2013.
- Abbey D. and Seshagiri P.B. Aza-induced cardiomyocyte differentiation-associated gene expression in mouse P19 EC-cells: role of DNA methylation, histone acetylation and ERK signaling. Gene 526: 364-373, 2013.
- Singh G., Totiger, T. Seshagiri P.B. Successful derivation of EGFP-transgenic embryonic stem cell line from a genetically non-permissive FVB/N mouse. Am. J. Stem Cell. 1: 163-173, 2012.
- Mariappa D., Aladakatti R.H., Dasari S.K., Sreekumar A., Wolkowicz M., Van der Hoorn F. and Seshagiri P.B. Inhibition of tyrosine phosphorylation of sperm flagellar proteins, outer dense fiber protein-2 and tektin-2, is associated with impaired motility during capacitation of hamster spermatozoa. Mol. Reprod. Dev., 77: 182-193, 2010.
- Seshagiri, P.B., Sen Roy, S., Sireesha, G. and Rao, R.P. Cellular and molecular regulation of mammalian blastocyst hatching. J. Reprod. Immunol., 83: 79–84, 2009.