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Diversity in genomic organisation, developmental regulation and distribution of the murine PR72/B" subunits of protein phosphatase 2A.

Zwaenepoel K, Louis JV, Goris J, Janssens V - BMC Genomics (2008)

Bottom Line: The subcellular localisation and cell cycle regulatory ability of several PR72/B" isoforms were determined, demonstrating differences as well as similarities.In contrast to PR55/B and PR61/B', the PR72/B" family seems evolutionary more divergent, as only two of the murine genes have a human orthologue.We have integrated these results in a more consistent nomenclature of both human and murine PR72/B" genes and their transcripts/proteins.

View Article: PubMed Central - HTML - PubMed

Affiliation: Protein Phosphorylation and Proteomics Group, Dept, Molecular Cell Biology, Faculty of Medicine, K,U, Leuven, Gasthuisberg O&N1, Herestraat 49 box 901, B-3000 Leuven, Belgium. Karen.Zwaenepoel@med.kuleuven.be

ABSTRACT

Background: Protein phosphatase 2A (PP2A) is a serine/threonine-specific phosphatase displaying vital functions in growth and development through its role in various signalling pathways. PP2A holoenzymes comprise a core dimer composed of a catalytic C and a structural A subunit, which can associate with a variable B-type subunit. The importance of the B-type subunits for PP2A regulation cannot be overestimated as they determine holoenzyme localisation, activity and substrate specificity. Three B-type subunit families have been identified: PR55/B, PR61/B' and PR72/B", of which the latter is currently the least characterised.

Results: We deduced the sequences and genomic organisation of the different murine PR72/B" isoforms: three genes encode nine isoforms, five of which are abundantly expressed and give rise to genuine PP2A subunits. Thereby, one novel subunit was identified. Using Northern blotting, we examined the tissue-specific and developmental expression of these subunits. All subunits are highly expressed in heart, suggesting an important cardiac function. Immunohistochemical analysis revealed a striated expression pattern of PR72 and PR130 in heart and skeletal muscle, but not in bladder smooth muscle. The subcellular localisation and cell cycle regulatory ability of several PR72/B" isoforms were determined, demonstrating differences as well as similarities.

Conclusion: In contrast to PR55/B and PR61/B', the PR72/B" family seems evolutionary more divergent, as only two of the murine genes have a human orthologue. We have integrated these results in a more consistent nomenclature of both human and murine PR72/B" genes and their transcripts/proteins. Our results provide a platform for the future generation of PR72/B" knockout mice.

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Immunohistochemistry of mPR130/B"α1 and mPR72/B"α2 in muscle tissue (heart, skeletal muscle and smooth muscle). A: Sections of bladder (a-c), skeletal muscle (d-f) and heart (g-i) were costained with the nuclei-specific hematoxylin dye (blue) and antibodies specific for mPR130/B"α1 (b, e, h) or mPR72/B"α2 (c, f, i). As a control, sections were stained with pre-immune sera (a, d, g). B: Staining of longitudinal sections of skeletal muscle with iron hematoxylin (a, b), PR130-specific AB (c,d), PR72-specific AB (e) and costaining with iron hematoxylin and PR130 AB (f) or PR72 AB (g).
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Figure 8: Immunohistochemistry of mPR130/B"α1 and mPR72/B"α2 in muscle tissue (heart, skeletal muscle and smooth muscle). A: Sections of bladder (a-c), skeletal muscle (d-f) and heart (g-i) were costained with the nuclei-specific hematoxylin dye (blue) and antibodies specific for mPR130/B"α1 (b, e, h) or mPR72/B"α2 (c, f, i). As a control, sections were stained with pre-immune sera (a, d, g). B: Staining of longitudinal sections of skeletal muscle with iron hematoxylin (a, b), PR130-specific AB (c,d), PR72-specific AB (e) and costaining with iron hematoxylin and PR130 AB (f) or PR72 AB (g).

Mentions: In longitudinal sections of skeletal muscle, mPR130/B"α1 and mPR72/B"α2 both intensively stain the muscle fibers in a striated pattern (Figure 8A, e–f). To evaluate whether these bands represent the I- or A-bands, we counterstained the sections with iron hematoxylin. This dye gives the A-band a dark blue colour and colocalises with mPR130/B"α1 and mPR72/B"α2 (Figure 8B, f–g). In one of the muscle fibers stained with mPR130/B"α1 AB, we could even observe a darker stained band positioned in the centre of the A-band (Figure 8B, d). This band probably represents the H-zone. In sections of murine myocardium, a similar striated staining pattern could be observed in the longitudinally positioned muscle fibers. Cross-sectional muscle fibers did not show staining of any specific structures (Figure 8A, h–i). In bladder, neither mPR130/B"α1 AB nor mPR72/B"α2 AB stained the smooth muscle fibers of the muscular layer. In contrast, mPR130/B"α1 staining could be seen in the transitional epithelial layer, lining the inner cavity of the bladder (Figure 8A, b–c). In none of the cases, specific staining of any structures was observed using pre-immune serum (Figure 8A, a,d,g).


Diversity in genomic organisation, developmental regulation and distribution of the murine PR72/B" subunits of protein phosphatase 2A.

Zwaenepoel K, Louis JV, Goris J, Janssens V - BMC Genomics (2008)

Immunohistochemistry of mPR130/B"α1 and mPR72/B"α2 in muscle tissue (heart, skeletal muscle and smooth muscle). A: Sections of bladder (a-c), skeletal muscle (d-f) and heart (g-i) were costained with the nuclei-specific hematoxylin dye (blue) and antibodies specific for mPR130/B"α1 (b, e, h) or mPR72/B"α2 (c, f, i). As a control, sections were stained with pre-immune sera (a, d, g). B: Staining of longitudinal sections of skeletal muscle with iron hematoxylin (a, b), PR130-specific AB (c,d), PR72-specific AB (e) and costaining with iron hematoxylin and PR130 AB (f) or PR72 AB (g).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2529318&req=5

Figure 8: Immunohistochemistry of mPR130/B"α1 and mPR72/B"α2 in muscle tissue (heart, skeletal muscle and smooth muscle). A: Sections of bladder (a-c), skeletal muscle (d-f) and heart (g-i) were costained with the nuclei-specific hematoxylin dye (blue) and antibodies specific for mPR130/B"α1 (b, e, h) or mPR72/B"α2 (c, f, i). As a control, sections were stained with pre-immune sera (a, d, g). B: Staining of longitudinal sections of skeletal muscle with iron hematoxylin (a, b), PR130-specific AB (c,d), PR72-specific AB (e) and costaining with iron hematoxylin and PR130 AB (f) or PR72 AB (g).
Mentions: In longitudinal sections of skeletal muscle, mPR130/B"α1 and mPR72/B"α2 both intensively stain the muscle fibers in a striated pattern (Figure 8A, e–f). To evaluate whether these bands represent the I- or A-bands, we counterstained the sections with iron hematoxylin. This dye gives the A-band a dark blue colour and colocalises with mPR130/B"α1 and mPR72/B"α2 (Figure 8B, f–g). In one of the muscle fibers stained with mPR130/B"α1 AB, we could even observe a darker stained band positioned in the centre of the A-band (Figure 8B, d). This band probably represents the H-zone. In sections of murine myocardium, a similar striated staining pattern could be observed in the longitudinally positioned muscle fibers. Cross-sectional muscle fibers did not show staining of any specific structures (Figure 8A, h–i). In bladder, neither mPR130/B"α1 AB nor mPR72/B"α2 AB stained the smooth muscle fibers of the muscular layer. In contrast, mPR130/B"α1 staining could be seen in the transitional epithelial layer, lining the inner cavity of the bladder (Figure 8A, b–c). In none of the cases, specific staining of any structures was observed using pre-immune serum (Figure 8A, a,d,g).

Bottom Line: The subcellular localisation and cell cycle regulatory ability of several PR72/B" isoforms were determined, demonstrating differences as well as similarities.In contrast to PR55/B and PR61/B', the PR72/B" family seems evolutionary more divergent, as only two of the murine genes have a human orthologue.We have integrated these results in a more consistent nomenclature of both human and murine PR72/B" genes and their transcripts/proteins.

View Article: PubMed Central - HTML - PubMed

Affiliation: Protein Phosphorylation and Proteomics Group, Dept, Molecular Cell Biology, Faculty of Medicine, K,U, Leuven, Gasthuisberg O&N1, Herestraat 49 box 901, B-3000 Leuven, Belgium. Karen.Zwaenepoel@med.kuleuven.be

ABSTRACT

Background: Protein phosphatase 2A (PP2A) is a serine/threonine-specific phosphatase displaying vital functions in growth and development through its role in various signalling pathways. PP2A holoenzymes comprise a core dimer composed of a catalytic C and a structural A subunit, which can associate with a variable B-type subunit. The importance of the B-type subunits for PP2A regulation cannot be overestimated as they determine holoenzyme localisation, activity and substrate specificity. Three B-type subunit families have been identified: PR55/B, PR61/B' and PR72/B", of which the latter is currently the least characterised.

Results: We deduced the sequences and genomic organisation of the different murine PR72/B" isoforms: three genes encode nine isoforms, five of which are abundantly expressed and give rise to genuine PP2A subunits. Thereby, one novel subunit was identified. Using Northern blotting, we examined the tissue-specific and developmental expression of these subunits. All subunits are highly expressed in heart, suggesting an important cardiac function. Immunohistochemical analysis revealed a striated expression pattern of PR72 and PR130 in heart and skeletal muscle, but not in bladder smooth muscle. The subcellular localisation and cell cycle regulatory ability of several PR72/B" isoforms were determined, demonstrating differences as well as similarities.

Conclusion: In contrast to PR55/B and PR61/B', the PR72/B" family seems evolutionary more divergent, as only two of the murine genes have a human orthologue. We have integrated these results in a more consistent nomenclature of both human and murine PR72/B" genes and their transcripts/proteins. Our results provide a platform for the future generation of PR72/B" knockout mice.

Show MeSH
Related in: MedlinePlus