Limits...
Synaptopodin: an actin-associated protein in telencephalic dendrites and renal podocytes.

Mundel P, Heid HW, Mundel TM, Krüger M, Reiser J, Kriz W - J. Cell Biol. (1997)

Bottom Line: In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins.The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity.From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Cell Biology, University of Heidelberg, Germany. peter.mundel@urz.uni-heidelberg.de

ABSTRACT
Synaptopodin is an actin-associated protein of differentiated podocytes that also occurs as part of the actin cytoskeleton of postsynaptic densities (PSD) and associated dendritic spines in a subpopulation of exclusively telencephalic synapses. Amino acid sequences determined in purified rat kidney and forebrain synaptopodin and derived from human and mouse brain cDNA clones show no significant homology to any known protein. In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins. The open reading frame of synaptopodin encodes a polypeptide with a calculated Mr of 73.7 kD (human)/74.0 kD (mouse) and an isoelectric point of 9.38 (human)/9. 27 (mouse). Synaptopodin contains a high amount of proline ( approximately 20%) equally distributed along the protein, thus virtually excluding the formation of any globular domain. Sequence comparison between human and mouse synaptopodin revealed 84% identity at the protein level. In both brain and kidney, in vivo and in vitro, synaptopodin gene expression is differentiation dependent. During postnatal maturation of rat brain, synaptopodin is first detected by Western blot analysis at day 15 and reaches maximum expression in the adult animal. The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity. From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

Show MeSH

Related in: MedlinePlus

Two-dimensional analysis of rat brain synaptopodin.  (a) Coomassie brilliant blue-stained two-dimensional Western  blot, using NEPHGE in the first dimension and SDS-PAGE in  the second, of a fraction enriched for synaptopodin (arrow) obtained after reversed-phase HPLC chromatography of a heat- stable supernatant from rat forebrain cytosolic extracts. (b) ECL  detection of synaptopodin using mAb G1.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2139823&req=5

Figure 2: Two-dimensional analysis of rat brain synaptopodin. (a) Coomassie brilliant blue-stained two-dimensional Western blot, using NEPHGE in the first dimension and SDS-PAGE in the second, of a fraction enriched for synaptopodin (arrow) obtained after reversed-phase HPLC chromatography of a heat- stable supernatant from rat forebrain cytosolic extracts. (b) ECL detection of synaptopodin using mAb G1.

Mentions: Using mAb G1, a heat-stable protein with an apparent molecular mass of 100 kD was recognized by immunoblotting in cytosolic extracts from rat brain (Fig. 1). In cytosolic fractions from isolated rat kidney glomeruli, a heat-stable band with an apparent molecular mass of 110 kD was shown (Fig. 1). The originally described 44-kD band (Mundel et al., 1991) represents a proteolytic fragment of the 110-kD protein (Fig. 1). On two-dimensional gel electrophoresis, synaptopodin appeared as a very basic protein with an isoelectric point around 9.4 (Fig. 2).


Synaptopodin: an actin-associated protein in telencephalic dendrites and renal podocytes.

Mundel P, Heid HW, Mundel TM, Krüger M, Reiser J, Kriz W - J. Cell Biol. (1997)

Two-dimensional analysis of rat brain synaptopodin.  (a) Coomassie brilliant blue-stained two-dimensional Western  blot, using NEPHGE in the first dimension and SDS-PAGE in  the second, of a fraction enriched for synaptopodin (arrow) obtained after reversed-phase HPLC chromatography of a heat- stable supernatant from rat forebrain cytosolic extracts. (b) ECL  detection of synaptopodin using mAb G1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139823&req=5

Figure 2: Two-dimensional analysis of rat brain synaptopodin. (a) Coomassie brilliant blue-stained two-dimensional Western blot, using NEPHGE in the first dimension and SDS-PAGE in the second, of a fraction enriched for synaptopodin (arrow) obtained after reversed-phase HPLC chromatography of a heat- stable supernatant from rat forebrain cytosolic extracts. (b) ECL detection of synaptopodin using mAb G1.
Mentions: Using mAb G1, a heat-stable protein with an apparent molecular mass of 100 kD was recognized by immunoblotting in cytosolic extracts from rat brain (Fig. 1). In cytosolic fractions from isolated rat kidney glomeruli, a heat-stable band with an apparent molecular mass of 110 kD was shown (Fig. 1). The originally described 44-kD band (Mundel et al., 1991) represents a proteolytic fragment of the 110-kD protein (Fig. 1). On two-dimensional gel electrophoresis, synaptopodin appeared as a very basic protein with an isoelectric point around 9.4 (Fig. 2).

Bottom Line: In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins.The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity.From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Cell Biology, University of Heidelberg, Germany. peter.mundel@urz.uni-heidelberg.de

ABSTRACT
Synaptopodin is an actin-associated protein of differentiated podocytes that also occurs as part of the actin cytoskeleton of postsynaptic densities (PSD) and associated dendritic spines in a subpopulation of exclusively telencephalic synapses. Amino acid sequences determined in purified rat kidney and forebrain synaptopodin and derived from human and mouse brain cDNA clones show no significant homology to any known protein. In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins. The open reading frame of synaptopodin encodes a polypeptide with a calculated Mr of 73.7 kD (human)/74.0 kD (mouse) and an isoelectric point of 9.38 (human)/9. 27 (mouse). Synaptopodin contains a high amount of proline ( approximately 20%) equally distributed along the protein, thus virtually excluding the formation of any globular domain. Sequence comparison between human and mouse synaptopodin revealed 84% identity at the protein level. In both brain and kidney, in vivo and in vitro, synaptopodin gene expression is differentiation dependent. During postnatal maturation of rat brain, synaptopodin is first detected by Western blot analysis at day 15 and reaches maximum expression in the adult animal. The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity. From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

Show MeSH
Related in: MedlinePlus