Our workgroup is interested in the function and differentiation of red blood cells (RBCs) of the chicken embryo. Due to the
key function of the RBCs for oxygen supply, interferences of the embryonic /fetal erythropoiesis are a fundamental cause of a
defect or abortive development.
The first population of the embryonic RBCs performs all steps of the terminal differentiation within the bloodstream and it allows access to normal erythroid progenitor cells which in adult organisms are normally found in the bone marrow. For this reason, the blood of the chicken embryo is an easy-accessible model to study aspects of embryonic/fetal RBC function and erythroid differentiation of vertebrates.
ATP as well UTP and CTP are the main allosteric effectors of the embryonic hemoglobins. Via in vivo hypoxia/hyperoxia,
characteristic changes of the nucleotide pattern occur which result in the modification of the O2 transport function of the
RBCs.We investigate the underlying cellular and biochemical mechanisms and the control by hormones.
(contact persons: Baumann, Dragon)
The stimulation of mid-to late-stage embryonic RBCs by ß-adrenergic or adenosine A2a receptor agonists and the subsequent
activation of the adenylyl cyclase lead to accumulation of the important erythroid enzymes carbonic anhydrase II and pyrimidine
nucleotidase I. The induction is the consequence of activated gene expression and is accompanied by the synthesis of other
regulatory proteins which are known to accompany differentiation processes of many cell types (epithelial, neuronal and
myogenic): We identified 1.) c-Fos, a transcription factor, 2.) TOB (=APRO6), a protein with anti-proliferative properties,
and 3.) IFR1 (=PC4=TIS7=IFRD1), a protein with supports differentiation by an unknown mechanism. We want to unravel the
cellular function of the three proteins in the context of the terminal differentiating RBCs to better understand the process
and regulation of terminal erythroid maturation.
(Contact person: Dragon)
The activation of receptors for purine- and pyrimidine nucleotides generally depends on the metabolisation of the
nucleotides (ATP, UTP) that are released by cells. During this process, embryonic RBCs play a key role: they are a source for
extra-cellular ATP/UTP/cAMP and due to their high 5'-ectonucleotidase activity, they are able to rapidly hydrolyse
extra-cellular nucleotides. We investigate the developmental profile, as well as the regulation of the
erythroid 5'-ectonucleotidase activity.
(Contact person: Baumann)