Calcitonin gene-related peptide and peripheral nerve regeneration.
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Animals↗
Biomedical subjects
C A Haas
Publications and source records attributed to C A Haas.
Gamma interferon-like immunoreactive material in rat neurons: evidence against a close relationship to gamma interferon.
Gamma interferon is a potent immunoregulatory peptide produced by activated lymphocytes. Recently, a gamma interferon-like immunoreactive molecule has been demonstrated immunohistochemically in subpopulations of rat neurons. We have now further characterized this molecule. Western blot analysis of spinal ganglia homogenates revealed a single 60,000 mol. wt band that was immunoreactive with monoclonal antibody DB1 directed against rat gamma interferon. A polyclonal antiserum and the monoclonal antibodies DB10 and DB12 failed to detect this band although all antibodies were able to label the major 18,000 mol. wt band of recombinant gamma interferon on the same blots. The 60,000 mol. wt band was selectively present in homogenates from primary sensory and sympathetic ganglia but was absent from the central nervous system and other peripheral organs, corresponding to the reported immunocytochemical distribution of gamma interferon-like immunoreactivity. The 60,000 mol. wt protein does not appear to be glycosylated. It could not be solubilized by detergents such as Triton X-100 and it co-purified with cytoskeleton-enriched preparations. At the nucleic acid level, Northern blot analysis using probes specific for rat gamma interferon mRNA failed to detect specific mRNA in rat spinal ganglia, whereas a strong 1.2 kb signal was detected in activated spleen cells. Functionally, gamma interferon-like immunoreactive material is strongly induced in superior cervical ganglion neurons after preganglionic axotomy of the sympathetic chain, but remains constant or slightly decreases in L5 spinal ganglion neurons after sciatic nerve transection. In contrast, major histocompatibility complex antigens are strongly induced on non-neuronal cells in both systems. We conclude that the neuronal gamma interferon-like immunoreactive material is clearly distinct from lymphocyte-derived gamma interferon and might not be involved in the control of major histocompatibility complex expression on glial cells.
Animals↗
Rat facial motoneurons express increased levels of calcitonin gene-related peptide mRNA in response to axotomy.
The expression and localization of the mRNA encoding the calcitonin gene-related peptide (CGRP) were analyzed in the rat facial nucleus after axotomy by Northern blot analysis and by in situ hybridization histochemistry (ISH) using a synthetic 32P-labeled oligonucleotide probe. Northern blot analysis revealed the presence of the 1.2 kb CGRP mRNA in RNA extracted from the facial nucleus. This mRNA species was strongly increased after axotomy of the facial nerve. By ISH increased levels of CGRP mRNA were observed as soon as 16 hr after axotomy compared with the unoperated nucleus. CGRP mRNA could be localized in more than 50% of the motoneurons. Three populations of motoneurons with no, moderate, or strong labeling for CGRP mRNA could be distinguished. Peak expression of CGRP mRNA during the first 48 hr was followed by a decline to moderate levels at day 4 after lesion, and to almost basal levels at days 7 and 9. These data demonstrate that axotomy of the facial nerve leads to an early and strong induction of CGRP gene expression in motoneurons of the facial nucleus.
Amino Acid Sequence↗
Synapsin I expression in the rat retina during postnatal development.
The expression of the synapsin I gene was studied during postnatal development of the rat retina at the mRNA and protein levels. In situ hybridization histochemistry showed that synapsin I mRNA was expressed already in nerve cells in the ganglion cell layer of the neonatal retina, while it appeared in neurons of the inner nuclear layer from postnatal day 4 onward. Maximal expression of synapsin I mRNA was observed at P12 in ganglion cells and in neurons of the inner nuclear layer followed by moderate expression in the adult. At the protein level a shift of synapsin I appearance was observed from cytoplasmic to terminal localization during retinal development by immunohistochemistry. In early stages (P4 and P8), synapsin I was seen in neurons of the ganglion cell layer and in neurons of the developing inner nuclear layer as well as in the developing inner plexiform layer. In the developing outer plexiform layer synapsin I was localized only in horizontal cells and in their processes. Its early appearance at P4 indicated the early maturation of this cell type. A shift and strong increase of labelling to the plexiform layers at P12 indicated the localization of synapsin I in synaptic terminals. The inner plexiform layer exhibited a characteristic stratified pattern. Photoreceptor cells never exhibited synapsin I mRNA or synapsin I protein throughout development.
Animals↗
Multiple synapsin I messenger RNAs are differentially regulated during neuronal development.
Synapsin I is a neuron-specific protein consisting of two isoforms Ia and Ib. It is thought to play a role in the regulation of neurotransmitter release. In this study the structure and expression of two classes of synapsin I mRNA have been examined. The two mRNA classes have molecular sizes of 3.4 and 4.5 kb, respectively. Both classes translate into synapsin I polypeptides and display a high degree of base sequence homology. Utilizing an oligonucleotide-directed RNase H assay we have shown that both mRNA classes have a common start site of transcription and differ from one another toward their 3' ends. The expression of the two synapsin I mRNA classes is differentially regulated during the development of the rat brain and cerebellum. In the cerebellum the 4.5-kb transcript is expressed until postnatal day 7, after which it decreases to an undetectable level. The 3.4-kb mRNA is found throughout cerebellar development and in the adult. This suggests that the 3.4-kb mRNA class consists of messages which can encode both synapsin I polypeptides. Using quantitative Northern blot analysis a peak in the expression of this mRNA was observed at postnatal day 20. The maximum expression of the 3.4-kb class coincides with the period of synaptogenesis in the cerebellum. In addition to the developmental time course of synapsin mRNA expression a description of its spatial distribution throughout the cerebellum was performed using in situ hybridization histochemistry. From postnatal day 15 onwards, with a maximum at postnatal day 20, synapsin mRNA was localized in the internal granule cell layer of the cerebellum. On a cellular level, the granule cells, but not the neighboring Purkinje cells, express high levels of synapsin mRNA. These observations implicate developmentally coordinated differential RNA splicing in the regulation of neuron-specific gene expression and substantiate the correlation of synapsin gene expression with the period of synaptogenic differentiation of neurons.
Animals↗
Role of NGF in axotomy-induced c-Jun expression in medial septal cholinergic neurons.
The extent of neuronal regeneration after axotomy largely depends on the survival capacity of the injured cell. It has been shown for a long time that nerve fiber transection results in retrograde changes in the parent neuronal cell body, and that these changes may eventually lead to neuronal degeneration. At present, little is known about the sequence of events initiated in a nerve cell body by the transection of its axonal process. In this report, we will focus on an interaction of nerve growth factor (NGF) with the transcription factor c-Jun in intact and axotomized septohippocampal projection neurons.
Animals↗