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Genomic structure and alternative splicing of murine R2B receptor protein tyrosine phosphatases (PTPkappa, mu, rho and PCP-2).

Besco J, Popesco MC, Davuluri RV, Frostholm A, Rotter A - BMC Genomics (2004)

Bottom Line: The greatest variability in genomic organization and the majority of alternatively spliced exons were observed in the juxtamembrane domain, a region critical for the regulation of signal transduction.Comparison of the four R2B RPTP genes revealed virtually identical principles of genomic organization, despite great disparities in gene size due to variations in intron length.Although subtle differences in exon length were also observed, it is likely that functional differences among these genes arise from the specific combinations of exons generated by alternative splicing.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology, The Ohio State University, Columbus, Ohio 43210, USA. besco.1@osu.edu

ABSTRACT

Background: Four genes designated as PTPRK (PTPkappa), PTPRL/U (PCP-2), PTPRM (PTPmu) and PTPRT (PTPrho) code for a subfamily (type R2B) of receptor protein tyrosine phosphatases (RPTPs) uniquely characterized by the presence of an N-terminal MAM domain. These transmembrane molecules have been implicated in homophilic cell adhesion. In the human, the PTPRK gene is located on chromosome 6, PTPRL/U on 1, PTPRM on 18 and PTPRT on 20. In the mouse, the four genes ptprk, ptprl, ptprm and ptprt are located in syntenic regions of chromosomes 10, 4, 17 and 2, respectively.

Results: The genomic organization of murine R2B RPTP genes is described. The four genes varied greatly in size ranging from approximately 64 kb to approximately 1 Mb, primarily due to proportional differences in intron lengths. Although there were also minor variations in exon length, the number of exons and the phases of exon/intron junctions were highly conserved. In situ hybridization with digoxigenin-labeled cRNA probes was used to localize each of the four R2B transcripts to specific cell types within the murine central nervous system. Phylogenetic analysis of complete sequences indicated that PTPrho and PTPmu were most closely related, followed by PTPkappa. The most distant family member was PCP-2. Alignment of RPTP polypeptide sequences predicted putative alternatively spliced exons. PCR experiments revealed that five of these exons were alternatively spliced, and that each of the four phosphatases incorporated them differently. The greatest variability in genomic organization and the majority of alternatively spliced exons were observed in the juxtamembrane domain, a region critical for the regulation of signal transduction.

Conclusions: Comparison of the four R2B RPTP genes revealed virtually identical principles of genomic organization, despite great disparities in gene size due to variations in intron length. Although subtle differences in exon length were also observed, it is likely that functional differences among these genes arise from the specific combinations of exons generated by alternative splicing.

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Type R2B gene expression in the adult mouse brain. In situ hybridization using digoxigenin-labeled riboprobes was used to localize the four R2B phosphatases in sagittal sections of a P180 male C57BL/6 mouse brain. PTPρ  (A-E), PTPμ (F-J), PTPκ (K-O), and PCP-2 (P-T) transcripts were present in various regions of the CNS including the olfactory bulb, cortex, hippocampus, and cerebellum. Olfactory bulb: ac, anterior commissure; g, granule layer; m, mitral cell layer; gl, glomerular layer; epl, external plexiform layer. Cortex: cortical layers I-VI. Hippocampus: d, dentate gyrus; h, hilus; or, oriens layer; py, pyramidal layer; r, radiatum layer; GII, Golgi II neurons. Cerebellum: dcn, deep cerebellar nuclei; ml, molecular layer; P, Purkinje cell layer; g, granule cell layer; G, Golgi cells. Arrowhead (D) shows anterior-posterior cerebellar boundary. Scale bars: Columns 1, 2 and 3 = 50 μm; column 4 = 500 μm; column 5 = 100 μm.
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Figure 9: Type R2B gene expression in the adult mouse brain. In situ hybridization using digoxigenin-labeled riboprobes was used to localize the four R2B phosphatases in sagittal sections of a P180 male C57BL/6 mouse brain. PTPρ (A-E), PTPμ (F-J), PTPκ (K-O), and PCP-2 (P-T) transcripts were present in various regions of the CNS including the olfactory bulb, cortex, hippocampus, and cerebellum. Olfactory bulb: ac, anterior commissure; g, granule layer; m, mitral cell layer; gl, glomerular layer; epl, external plexiform layer. Cortex: cortical layers I-VI. Hippocampus: d, dentate gyrus; h, hilus; or, oriens layer; py, pyramidal layer; r, radiatum layer; GII, Golgi II neurons. Cerebellum: dcn, deep cerebellar nuclei; ml, molecular layer; P, Purkinje cell layer; g, granule cell layer; G, Golgi cells. Arrowhead (D) shows anterior-posterior cerebellar boundary. Scale bars: Columns 1, 2 and 3 = 50 μm; column 4 = 500 μm; column 5 = 100 μm.

Mentions: In the present study, digoxigenin–labeled cRNA probes were used to determine the cellular localization of R2B transcripts in specific regions of the adult (P180) mouse brain: The olfactory bulb, cerebral cortex, hippocampus and cerebellum (Figure 9). Each of the four R2B transcripts was expressed at moderate to high levels in the mitral, external granule and glomerular layers of the olfactory bulb, and at lower levels in the external plexiform layer. All four R2B transcripts were distributed throughout the cerebral cortex, with the highest levels observed in layers II, IV, and V (PTPρ), IV and V (PTPμ), II to V (PTPκ), and II through VI (PCP-2). Within the hippocampus and dentate gyrus, large cells (Golgi II neurons) scattered throughout the hippocampal CA1, CA2, and CA3 regions, oriens and pyramidal layers, the hilus and subiculum, expressed PTPρ and PTPμ at very high levels. The PTPκ and PCP-2 transcripts were also present in Golgi II neurons, however, expression was restricted to cells in the hilus (PTPκ, PCP-2) and subiculum (PCP-2). Much higher expression levels were present in hippocampal pyramidal cells and dentate granule cells. Each of the four R2B transcripts was differentially expressed in the cerebellum. PTPρ mRNA was almost entirely restricted to the granule cell layer of lobules 1–6 of the cerebellar cortex and deep cerebellar neurons; very sparse labeling was also present in basket and stellate cells in the molecular layer. PTPμ was expressed at high levels in the Purkinje cells, and at much lower levels in Golgi, stellate and basket cells. The PTPκ transcript was present at low levels in basket, stellate, Golgi and granule cells throughout the cerebellar molecular and granule cell layers. PCP-2 was expressed at moderate levels in granule and Purkinje cells, and at lower levels in basket and stellate cells, and in deep cerebellar neurons. The sense signal for each of the four genes (not shown) was very low and distributed uniformly across sections, indicating that non-specific expression was negligible. These studies show that each of the four R2B transcripts exhibit exclusive, as well as overlapping, distribution patterns.


Genomic structure and alternative splicing of murine R2B receptor protein tyrosine phosphatases (PTPkappa, mu, rho and PCP-2).

Besco J, Popesco MC, Davuluri RV, Frostholm A, Rotter A - BMC Genomics (2004)

Type R2B gene expression in the adult mouse brain. In situ hybridization using digoxigenin-labeled riboprobes was used to localize the four R2B phosphatases in sagittal sections of a P180 male C57BL/6 mouse brain. PTPρ  (A-E), PTPμ (F-J), PTPκ (K-O), and PCP-2 (P-T) transcripts were present in various regions of the CNS including the olfactory bulb, cortex, hippocampus, and cerebellum. Olfactory bulb: ac, anterior commissure; g, granule layer; m, mitral cell layer; gl, glomerular layer; epl, external plexiform layer. Cortex: cortical layers I-VI. Hippocampus: d, dentate gyrus; h, hilus; or, oriens layer; py, pyramidal layer; r, radiatum layer; GII, Golgi II neurons. Cerebellum: dcn, deep cerebellar nuclei; ml, molecular layer; P, Purkinje cell layer; g, granule cell layer; G, Golgi cells. Arrowhead (D) shows anterior-posterior cerebellar boundary. Scale bars: Columns 1, 2 and 3 = 50 μm; column 4 = 500 μm; column 5 = 100 μm.
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Figure 9: Type R2B gene expression in the adult mouse brain. In situ hybridization using digoxigenin-labeled riboprobes was used to localize the four R2B phosphatases in sagittal sections of a P180 male C57BL/6 mouse brain. PTPρ (A-E), PTPμ (F-J), PTPκ (K-O), and PCP-2 (P-T) transcripts were present in various regions of the CNS including the olfactory bulb, cortex, hippocampus, and cerebellum. Olfactory bulb: ac, anterior commissure; g, granule layer; m, mitral cell layer; gl, glomerular layer; epl, external plexiform layer. Cortex: cortical layers I-VI. Hippocampus: d, dentate gyrus; h, hilus; or, oriens layer; py, pyramidal layer; r, radiatum layer; GII, Golgi II neurons. Cerebellum: dcn, deep cerebellar nuclei; ml, molecular layer; P, Purkinje cell layer; g, granule cell layer; G, Golgi cells. Arrowhead (D) shows anterior-posterior cerebellar boundary. Scale bars: Columns 1, 2 and 3 = 50 μm; column 4 = 500 μm; column 5 = 100 μm.
Mentions: In the present study, digoxigenin–labeled cRNA probes were used to determine the cellular localization of R2B transcripts in specific regions of the adult (P180) mouse brain: The olfactory bulb, cerebral cortex, hippocampus and cerebellum (Figure 9). Each of the four R2B transcripts was expressed at moderate to high levels in the mitral, external granule and glomerular layers of the olfactory bulb, and at lower levels in the external plexiform layer. All four R2B transcripts were distributed throughout the cerebral cortex, with the highest levels observed in layers II, IV, and V (PTPρ), IV and V (PTPμ), II to V (PTPκ), and II through VI (PCP-2). Within the hippocampus and dentate gyrus, large cells (Golgi II neurons) scattered throughout the hippocampal CA1, CA2, and CA3 regions, oriens and pyramidal layers, the hilus and subiculum, expressed PTPρ and PTPμ at very high levels. The PTPκ and PCP-2 transcripts were also present in Golgi II neurons, however, expression was restricted to cells in the hilus (PTPκ, PCP-2) and subiculum (PCP-2). Much higher expression levels were present in hippocampal pyramidal cells and dentate granule cells. Each of the four R2B transcripts was differentially expressed in the cerebellum. PTPρ mRNA was almost entirely restricted to the granule cell layer of lobules 1–6 of the cerebellar cortex and deep cerebellar neurons; very sparse labeling was also present in basket and stellate cells in the molecular layer. PTPμ was expressed at high levels in the Purkinje cells, and at much lower levels in Golgi, stellate and basket cells. The PTPκ transcript was present at low levels in basket, stellate, Golgi and granule cells throughout the cerebellar molecular and granule cell layers. PCP-2 was expressed at moderate levels in granule and Purkinje cells, and at lower levels in basket and stellate cells, and in deep cerebellar neurons. The sense signal for each of the four genes (not shown) was very low and distributed uniformly across sections, indicating that non-specific expression was negligible. These studies show that each of the four R2B transcripts exhibit exclusive, as well as overlapping, distribution patterns.

Bottom Line: The greatest variability in genomic organization and the majority of alternatively spliced exons were observed in the juxtamembrane domain, a region critical for the regulation of signal transduction.Comparison of the four R2B RPTP genes revealed virtually identical principles of genomic organization, despite great disparities in gene size due to variations in intron length.Although subtle differences in exon length were also observed, it is likely that functional differences among these genes arise from the specific combinations of exons generated by alternative splicing.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology, The Ohio State University, Columbus, Ohio 43210, USA. besco.1@osu.edu

ABSTRACT

Background: Four genes designated as PTPRK (PTPkappa), PTPRL/U (PCP-2), PTPRM (PTPmu) and PTPRT (PTPrho) code for a subfamily (type R2B) of receptor protein tyrosine phosphatases (RPTPs) uniquely characterized by the presence of an N-terminal MAM domain. These transmembrane molecules have been implicated in homophilic cell adhesion. In the human, the PTPRK gene is located on chromosome 6, PTPRL/U on 1, PTPRM on 18 and PTPRT on 20. In the mouse, the four genes ptprk, ptprl, ptprm and ptprt are located in syntenic regions of chromosomes 10, 4, 17 and 2, respectively.

Results: The genomic organization of murine R2B RPTP genes is described. The four genes varied greatly in size ranging from approximately 64 kb to approximately 1 Mb, primarily due to proportional differences in intron lengths. Although there were also minor variations in exon length, the number of exons and the phases of exon/intron junctions were highly conserved. In situ hybridization with digoxigenin-labeled cRNA probes was used to localize each of the four R2B transcripts to specific cell types within the murine central nervous system. Phylogenetic analysis of complete sequences indicated that PTPrho and PTPmu were most closely related, followed by PTPkappa. The most distant family member was PCP-2. Alignment of RPTP polypeptide sequences predicted putative alternatively spliced exons. PCR experiments revealed that five of these exons were alternatively spliced, and that each of the four phosphatases incorporated them differently. The greatest variability in genomic organization and the majority of alternatively spliced exons were observed in the juxtamembrane domain, a region critical for the regulation of signal transduction.

Conclusions: Comparison of the four R2B RPTP genes revealed virtually identical principles of genomic organization, despite great disparities in gene size due to variations in intron length. Although subtle differences in exon length were also observed, it is likely that functional differences among these genes arise from the specific combinations of exons generated by alternative splicing.

Show MeSH
Related in: MedlinePlus