ABSTRACT
The edg-1 immediate-early gene encodes a G-protein-coupled receptor homolog implicated in endothelial cell differentiation. We report the cloning of the rat edg-1 gene. Our Northern analyses indicate that edg-1 is much more widely expressed than previously thought. edg-1 mRNA was found in many organs at several stages of development with relatively high levels present in adult brain. edg-1 transcripts were also detected in several cell lines. Expression of edg-1 mRNA in the PC12 cell model of neuronal differentiation was unaffected by agents that cause PC12 cells to differentiate or proliferate. Therefore, edg-1 may play a cell-type-specific role in differentiation and also participate in neurotransmission.
Subject(s)
Brain/metabolism , Gene Expression , Genes, Immediate-Early , Immediate-Early Proteins/genetics , Rats/genetics , Receptors, Cell Surface , Receptors, G-Protein-Coupled , Aging , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern , Brain/embryology , Brain/growth & development , Cell Differentiation , Cell Line , Cloning, Molecular , Embryonic and Fetal Development , Gestational Age , Humans , Immediate-Early Proteins/biosynthesis , Molecular Sequence Data , Neurons/physiology , Organ Specificity , PC12 Cells , RNA, Messenger/analysis , RNA, Messenger/biosynthesis , Receptors, Lysophospholipid , Sequence Homology, Amino AcidABSTRACT
Ciliary neurotrophic factor (CNTF) has been shown to modulate the in vitro and in vivo survival, proliferation and differentiation of many neuronal cell types. Evidence indicates that it produces most if not all these effects by binding to a receptor subunit referred to as the CNTF receptor alpha component (CNTFR alpha). We cloned a cDNA encoding part of the rat CNTFR alpha and used it in Northern analyses to study CNTFR alpha mRNA expression. Examination of various tissues of embryonic day 18 and postnatal day 14 rats indicated that CNTFR alpha mRNA is primarily but not exclusively expressed in brain at these stages of development. Further studies revealed that the CNTFR alpha transcripts are present throughout brain development from embryonic day 12 to adulthood and display a widespread distribution in the adult brain. A survey of rodent cell lines detected highest CNTFR alpha mRNA concentrations in neuronal lines and a low concentration in a Schwann cell derived line. CNTFR alpha mRNA was not detected in fibroblast lines and a glioma line. Finally, nerve growth factor treatment decreased CNTFR alpha mRNA levels in PC12 cells. This result demonstrates that signal transduction processes activated by a neurotrophin can influence CNTF activated signal transduction processes. Such cross-talk may play an important in vivo role in the development and maintenance of the many neuronal cell types that are responsive to both neurotrophins and CNTF.
Subject(s)
Gene Expression Regulation, Developmental/physiology , RNA, Messenger/biosynthesis , Receptors, Nerve Growth Factor/genetics , Animals , Brain/embryology , Brain/growth & development , Brain/metabolism , Cell Line , Cloning, Molecular , Embryonic and Fetal Development/genetics , PC12 Cells , Rats , Receptor, Ciliary Neurotrophic Factor , Schwann Cells/metabolismABSTRACT
Polymerase chain reaction techniques and medium stringency library screening were used to isolate a rat cDNA ("H218") which encodes a novel guanine nucleotide-binding protein coupled receptor homolog ("pH218"). Northern analysis revealed that brain H218 mRNA is preferentially expressed during embryogenesis. In addition, H218 mRNA is expressed in all developing tissues and rodent cell lines examined with highest levels detected in primitive, transformed cells. H218 mRNA expression in cell lines is rapidly increased by a tumor promoter and rapidly decreased by a differentiation-inducing growth factor. Finally, all of the sequence motifs characteristic of Src homology 2 domains are present in pH218 but in a unique arrangement. We conclude that pH218 may function as a growth factor receptor.