Biomedical subjects

D H Blohm

Publications and source records attributed to D H Blohm.

4 recordsLinked to original sources

PubMed2001

New developments in microarray technology.

Microarrays have emerged as indispensable research tools for gene expression profiling and mutation analysis. New classification of cancer subtypes, dissecting the yeast metabolism and large-scale genotyping of human single nucleotide polymorphisms are important results being obtained with this technique. Realizing the microsphere-based massively parallel signature sequencing technique as fluid microarrays, building new types of protein arrays and constructing miniaturized flow-through systems, which can potentially take this technology from the research bench into industrial, clinical and other routine applications, exemplify the intense developments that are now ongoing in this field.

Biotechnology↗

PubMed1997

Expression of eight metabotropic glutamate receptor subtypes during neuronal differentiation of P19 embryocarcinoma cells: a study by RT-PCR and in situ hybridization.

Metabotropic glutamate receptors modulate neuronal activity but expression and alternative splicing of their subtypes (mGluR1-mGluR8) during early neuronal differentiation are essentially unknown. In the mouse embryocarcinoma cell line P19, one of the best established systems to study neurogenesis in vitro, it was shown by RT-PCR and in situ hybridization that the neuronal differentiation process, induced by retinoic acid, is characterized by an early increase in the expression of mGluR3, mGluR7 and mGluR8 and a late rise in the mRNA levels of mGluR1 and mGluR5, whereas mGluR2 and mGluR4 seem to be constitutively expressed. In comparison, in primary embryonic neurons all mGluR subtypes were detected at day 3 after plating while primary astrocytes and oligodendrocytes have diverging mGluR pattern. In addition, the splicing pattern of mGluR1 and mGluR5 transcripts differ remarkably between neural cells in vitro and brain tissue. These data, although not comparable to the situation in vivo, might be a hint on so far unknown functions of metabotropic glutamate receptors during neuronal differentiation.

Animals↗

PubMed1997

Expression and mRNA splicing of glycine receptor subunits and gephyrin during neuronal differentiation of P19 cells in vitro, studied by RT-PCR and immunocytochemistry.

The mouse EC cell line P19, differentiating in vitro into neural cell types under the influence of retinoic acid, represents a well established model system for neurogenesis. In this system the expression of the alpha (alpha 1-alpha 3) and beta subunits of the inhibitory glycine receptor (GlyR) and of gephyrin as well as their mRNA splice variants was analyzed by RT-PCR and by immunocytochemistry. In the course of neuronal differentiation of P19 cells mRNA of GlyR beta is constitutively expressed, GlyR alpha 1 and alpha 2 are induced and GlyR alpha 3 was not detected. From the three gephyrin transcripts known to be differently spliced in the C3/C4 cassette region, the C3 transcript was found at all stages while the C4 transcript was not detectable. The insert-free form was measurable in P19 cells only 3-4 days post induction by retinoic acid. In addition a GlyR beta splice variant and a fourth gephyrin transcript were detected. Primary glial cells do not contain significant amounts of GlyR alpha subunits while in primary neuronal cells transcripts of GlyR alpha 2 were found as well as the mRNA of the GlyR beta subunit and of gephyrin. PC12 cells do not express glycine receptor genes but do express gephyrin. Immunocytochemistry confirmed the constitutive expression of gephyrin at the protein level, whereas GlyR antigens could only be detected in islets of the 'P19 neurons'. In conclusion, P19 and primary neuronal cells but not PC12 cells express the transcripts of glycine receptor components, necessary to generate functional receptors.

Animals↗

PubMed1996

The RNA binding protein HuD: rat cDNA and analysis of the alternative spliced mRNA in neuronal differentiating cell lines P19 and PC12.

HuD belongs to a family of neurospecific RNA binding proteins found in man, frog and fly [49]. To investigate whether this protein is involved in regulation of neuronal differentiation of rodent cells in vivo and in vitro, the cDNA of the rat homolog gene (r-HuD) was cloned, its expression was studied in rat brain and in neurogenic cell lines, and the splicing of its RNA was analyzed. Coding sequences of HuD from man and rat were found to be 99.5 and 95% identical at protein and DNA level, respectively. In rat brain r-HuD transcripts 3.7 and 4.2 kb in length were detected by Northern blot analysis. RT-PCR and in situ hybridization revealed that rodent homologues of HuD transcripts are present in P19 mouse embryo carcinoma and in PC12 rat pheochromocytoma cell lines both able to differentiate into neurons. In contrast, r-HuD transcripts were not detectable in the rat glioma cell line C6. In P19 cells a strong induction of HuD mRNA was observed after triggering neuronal differentiation by retinoic acid, whereas in PC12 cells the mRNA was present before and after nerve growth factor (NGF) induced neuronal differentiation. In both neuronal cell lines and in brain of adult rat and mouse HuD mRNA is alternatively spliced in a region which encodes a proline rich linker domain between the second and third RNA recognition motif. This RNA processing event seems to be differently regulated in PC12 cells on the one hand, and in P19 cells and brain of rat and mouse on the other.

Alternative Splicing↗