Biomedical subjects

Mira C Puri

Publications and source records attributed to Mira C Puri.

3 recordsLinked to original sources

PubMed2005

Selective role of a distinct tyrosine residue on Tie2 in heart development and early hematopoiesis.

The development of the cardiovascular system and the development of the early hematopoietic systems are closely related, and both require signaling through the Tie2 receptor tyrosine kinase. Although endothelial cells and hematopoietic cells as well as their precursors share common gene expression patterns during development, it remains completely unknown how Tie2 signaling coordinately regulates cardiovascular development and early hematopoiesis in vivo. We show here that mice with a targeted mutation in tyrosine residue 1100 in the carboxyl-terminal tail of Tie2 display defective cardiac development and impaired hematopoietic and endothelial cell development in the paraaortic splanchnopleural mesoderm similar to that seen in Tie2-null mutant mice. Surprisingly, however, unlike Tie2-null mutant mice, mice deficient in signaling through this tyrosine residue show a normal association of perivascular cells with nascent blood vessels. These studies are the first to demonstrate the physiological importance of a single tyrosine residue in Tie2, and they suggest that multiple tyrosine residues in the receptor may coordinate cardiovascular development and early hematopoietic development.

Animals↗

PubMed2003

Requirement for the TIE family of receptor tyrosine kinases in adult but not fetal hematopoiesis.

In mammals, the continuous production of hematopoietic cells (HCs) is sustained by a small number of hematopoietic stem cells (HSCs) residing in the bone marrow. Early HSC activity arises in the aorta-gonad mesonephros region, within cells localized to the ventral floor of the major blood vessels, suggesting that the first HSCs may be derived from cells capable of giving rise to the hematopoietic system and to the endothelial cells of the vasculature. TIE1 (TIE) and TIE2 (TEK) are related receptor tyrosine kinases with an embryonic expression pattern in endothelial cells, their precursors, and HCs, suggestive of a role in the divergence and function of both lineages. Indeed, gene targeting approaches have shown that TIE1, TIE2, and ligands for TIE2, the angiopoietins, are essential for vascular development and maintenance. To explore possible roles for these receptors in HCs, we have examined the ability of embryonic cells lacking both TIE1 and TIE2 to contribute to developmental and adult hematopoiesis by generating chimeric animals between normal embryonic cells and cells lacking these receptors. We show here that TIE receptors are not required for differentiation and proliferation of definitive hematopoietic lineages in the embryo and fetus; surprisingly, however, these receptors are specifically required during postnatal bone marrow hematopoiesis.

Aging↗

PubMed2003

A unique pattern of Tie1 expression in the developing murine lung.

The molecular mechanisms responsible for organ-specific differences in vascular development are not well established. Animals lacking the receptor tyrosine kinase Tie1 die of hemorrhage and pulmonary edema. Furthermore, cells lacking Tie1 are excluded from blood vessels of the mature lung. These findings suggest the importance of Tie1 in the pulmonary vasculature. We quantified the organ-specific expression of Tie1 during embryonic and postnatal murine development using both quantitative real-time polymerase chain reaction (PCR) and chemiluminescence employing a tie1.lacZ reporter. In the lung, Tie1 expression increases markedly immediately prior to birth and rises further in the newborn animal, a pattern not found in other organs. Furthermore, expression of Tie1 in the lung is also unique by its persistent increase in the adult animal. This unique pattern of Tie1 gene expression in the embryonic and mature lung supports a distinct role for Tie1 in the development and function of the pulmonary vasculature.

Animals↗