Allelic Gene Regulation of Pcdh-α and Pcdh-γ Clusters Involving Both Monoallelic and Biallelic Expression in Single Purkinje Cells

Abstract

The molecular basis for providing the identity and diversity of single neurons is a key for realizing the brain system. Diverse protocadherin isoforms encoded by the Pcdh-α and Pcdh-γ gene clusters are expressed in all of the vertebrates studied. For the Pcdh-α isoforms, differential expression patterns have been found in single Purkinje cells by unusual monoallelic and combinatorial types of gene regulation. Here we investigated total allelic gene regulation in the Pcdh-α and -γ clusters, including the C-type variable exons (C1 to C5) and the Pcdh-γA and -γB variable exons in single Purkinje cells. Using split single-cell reverse transcription-PCR analysis, almost all of the Purkinje cells at postnatal day 21 biallelically expressed all the C-type isoforms, whereas the Pcdh-α isoforms showed both monoallelic and combinatorial expression. The Pcdh-γA and -γB isoforms also showed differential regulation in each cell with both monoallelic and combinatorial gene regulation. These data indicated that different types of allelic gene regulation (monoallelic versus biallelic) occurred in the Pcdh-α and -γ clusters, although they were spliced into the same constant exons. It has been reported that each C-type Pcdh-α or -γ transcript has a different expression pattern during brain development, suggesting that the different C-type variable exons may code temporal diversity, although the Pcdh-α, -γA, and -γB isoforms were differential and combinatorial gene regulation within a single cell. Thus, the multiple gene regulations in the Pcdh-α and -γ clusters had a potential mechanism for increasing the diversity of individual neurons in the brain. The molecular basis for providing the identity and diversity of single neurons is a key for realizing the brain system. Diverse protocadherin isoforms encoded by the Pcdh-α and Pcdh-γ gene clusters are expressed in all of the vertebrates studied. For the Pcdh-α isoforms, differential expression patterns have been found in single Purkinje cells by unusual monoallelic and combinatorial types of gene regulation. Here we investigated total allelic gene regulation in the Pcdh-α and -γ clusters, including the C-type variable exons (C1 to C5) and the Pcdh-γA and -γB variable exons in single Purkinje cells. Using split single-cell reverse transcription-PCR analysis, almost all of the Purkinje cells at postnatal day 21 biallelically expressed all the C-type isoforms, whereas the Pcdh-α isoforms showed both monoallelic and combinatorial expression. The Pcdh-γA and -γB isoforms also showed differential regulation in each cell with both monoallelic and combinatorial gene regulation. These data indicated that different types of allelic gene regulation (monoallelic versus biallelic) occurred in the Pcdh-α and -γ clusters, although they were spliced into the same constant exons. It has been reported that each C-type Pcdh-α or -γ transcript has a different expression pattern during brain development, suggesting that the different C-type variable exons may code temporal diversity, although the Pcdh-α, -γA, and -γB isoforms were differential and combinatorial gene regulation within a single cell. Thus, the multiple gene regulations in the Pcdh-α and -γ clusters had a potential mechanism for increasing the diversity of individual neurons in the brain. The brain contains a huge number of neurons that have diverse characteristics and identities to enable the generation of complex neuronal networks. Therefore, the molecular mechanism for specifying the identity and diversity of single neurons is important for realizing the complexity of the brain. Approximately 100 diverse cadherin superfamily genes are highly expressed in the brain (1Yagi T. Takeichi M. Genes Dev. 2000; 14: 1169-1180PubMed Google Scholar, 2Hamada S. Yagi T. Neurosci. Res. 2001; 41: 207-215Crossref PubMed Scopus (35) Google Scholar). Among them, the CNRs (cadherin-related neuronal receptors) are also diverse and highly expressed in the vertebrate brain (3Kohmura N. Senzaki K. Hamada S. Kai N. Yasuda R. Watanabe M. Ishii H. Yasuda M. Mishina M. Yagi T. Neuron. 1998; 20: 1137-1151Abstract Full Text Full Text PDF PubMed Scopus (387) Google Scholar). The CNRs are Pcdh-α (protocadherin-α) genes. Their diverse isoforms are generated from gene clusters on chromosomes; these clusters of Pcdh-α and Pcdh-γ contain variable regions (tandemly arrayed diverse variable exons) and constant regions (common, cis-spliced exons of Pcdh-α and Pcdh-γ) (4Wu Q. Maniatis T. Cell. 1999; 97: 779-790Abstract Full Text Full Text PDF PubMed Scopus (564) Google Scholar, 5Wu Q. Maniatis T. Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 3124-3129Crossref PubMed Scopus (97) Google Scholar, 6Sugino H. Hamada S. Yasuda R. Tuji A. Matsuda Y. Fujita M. Yagi T. Genomics. 2000; 63: 75-87Crossref PubMed Scopus (106) Google Scholar, 7Sugino H. Yanase H. Hamada S. Kurokawa K. Asakawa S. Shimizu N. Yagi T. Biochem. Biophys. Res. Commun. 2004; 316: 437-445Crossref PubMed Scopus (17) Google Scholar, 8Tada M.N. Senzaki K. Tai Y. Morishita H. Tanaka Y.Z. Murata Y. Ishii Y. Asakawa S. Shimizu N. Sugino H. Yagi T. Gene (Amst.). 2004; 340: 197-211Crossref PubMed Scopus (34) Google Scholar, 9Yanase H. Sugino H. Yagi T. Genomics. 2004; 83: 717-726Crossref PubMed Scopus (20) Google Scholar, 10Wu Q. Zhang T. Cheng J.F. Kim Y. Grimwood J. Schmutz J. Dickson M. Noonan J.P. Zhang M.Q. Myers R.M. Maniatis T. Genome. Res. 2001; 11: 389-404Crossref PubMed Scopus (203) Google Scholar, 11Wu Q. Genetics. 2005; 169: 2179-2188Crossref PubMed Scopus (70) Google Scholar, 12Noonan J.P. Grimwood J. Danke J. Schmutz J. Dickson M. Amemiya C.T. Myers R.M. Genome Res. 2004; 14: 2397-2405Crossref PubMed Scopus (64) Google Scholar). Their genomic organization is similar to that of immunoglobulin and T-cell receptor genes (3Kohmura N. Senzaki K. Hamada S. Kai N. Yasuda R. Watanabe M. Ishii H. Yasuda M. Mishina M. Yagi T. Neuron. 1998; 20: 1137-1151Abstract Full Text Full Text PDF PubMed Scopus (387) Google Scholar). This diversity of Pcdh cluster genes could be one of the mechanisms by which neurons are distinguished from each other. The single-cell analysis of Purkinje cells using multiple RT-PCRs showed that the expression of each variable exon in the Pcdh-α gene is monoallelic and combinatorial (13Esumi S. Kakazu N. Taguchi Y. Hirayama T. Sasaki A. Hirabayashi T. Koide T. Kitsukawa T. Hamada S. Yagi T. Nat. Genet. 2005; 37: 171-176Crossref PubMed Scopus (204) Google Scholar). This was a novel type of allelic expression for diversified receptor families in the brain. The differential expression patterns of the Pcdh-α isoforms in single neurons also suggested a mechanism for providing the identity and specificity of single neurons in the brain (13Esumi S. Kakazu N. Taguchi Y. Hirayama T. Sasaki A. Hirabayashi T. Koide T. Kitsukawa T. Hamada S. Yagi T. Nat. Genet. 2005; 37: 171-176Crossref PubMed Scopus (204) Google Scholar). The variable exons of the Pcdh-α and Pcdh-γ clusters are classified into several subgroups, Pcdh-α, Pcdh-γA, Pcdh-γB, and C-type (4Wu Q. Maniatis T. Cell. 1999; 97: 779-790Abstract Full Text Full Text PDF PubMed Scopus (564) Google Scholar, 10Wu Q. Zhang T. Cheng J.F. Kim Y. Grimwood J. Schmutz J. Dickson M. Noonan J.P. Zhang M.Q. Myers R.M. Maniatis T. Genome. Res. 2001; 11: 389-404Crossref PubMed Scopus (203) Google Scholar). The Pcdh-α gene cluster contains the variable exons Pcdh-α1to Pcdh-α12, and in addition, α7/8 exists in wild mouse strains and two C-type variable exons, C1 and C2 (10Wu Q. Zhang T. Cheng J.F. Kim Y. Grimwood J. Schmutz J. Dickson M. Noonan J.P. Zhang M.Q. Myers R.M. Maniatis T. Genome. Res. 2001; 11: 389-404Crossref PubMed Scopus (203) Google Scholar, 14Taguchi Y. Koide T. Shiroishi T. Yagi T. Mol. Biol. Evol. 2005; 22: 1433-1443Crossref PubMed Scopus (16) Google Scholar, 15Takei Y. Hamada S. Senzaki K. Mutoh T. Sugino H. Yagi T. Genomics. 2001; 72: 321-330Crossref PubMed Scopus (18) Google Scholar). The Pcdh-γ gene cluster contains Pcdh-γA, Pcdh-γB, and three C-type variable exons, C3, C4, and C5 (10Wu Q. Zhang T. Cheng J.F. Kim Y. Grimwood J. Schmutz J. Dickson M. Noonan J.P. Zhang M.Q. Myers R.M. Maniatis T. Genome. Res. 2001; 11: 389-404Crossref PubMed Scopus (203) Google Scholar). The five C-type variable exons of Pcdh-α and Pcdh-γ are highly homologous to each other and distinct from the other exons in the clusters. Here we examined the allelic gene regulation of these types of variable exons in the Pcdh-α and Pcdh-γ gene clusters at the single-cell level. Interestingly, the C-type variable exons were constantly expressed in Purkinje cells at postnatal day (P) 3The abbreviations used are: Pn, postnatal day n; B6, C57BL/6; RT, reverse transcription. 21 from both alleles, although monoallelic and combinatorial types of expression were commonly found for the Pcdh-α, Pcdh-γA, and Pcdh-γB variable exons. Our results indicated that biallelic and monoallelic gene regulation for variable exons coexist for each Pcdh gene cluster. The monoallelic and combinatorial expression of distinct Pcdh-α, Pcdh-γA, and Pcdh-γB variable exons is a potential mechanism for generating distinct identity in single Purkinje cells. Animals—F1 hybrid offspring were obtained by intercrossing mice of the laboratory strain C57BL/6 (B6) (Purchased from Charles River) with the Japanese wild mouse strain JF1, obtained from the National Institute for Genetics (Mishima, Shizuoka, Japan). The mouse strain JF1 is different from that of our previous report (13Esumi S. Kakazu N. Taguchi Y. Hirayama T. Sasaki A. Hirabayashi T. Koide T. Kitsukawa T. Hamada S. Yagi T. Nat. Genet. 2005; 37: 171-176Crossref PubMed Scopus (204) Google Scholar) but shares similar polymorphisms in Pcdh-α locus. The JF1 mice show more suitable characteristics for daily care than MSM mice. In Situ Hybridization—In situ hybridization was performed as described previously (13Esumi S. Kakazu N. Taguchi Y. Hirayama T. Sasaki A. Hirabayashi T. Koide T. Kitsukawa T. Hamada S. Yagi T. Nat. Genet. 2005; 37: 171-176Crossref PubMed Scopus (204) Google Scholar, 16Schaeren-Wiemers N. Gerfin-Moser A. Histochemistry. 1993; 100: 431-440Crossref PubMed Scopus (1086) Google Scholar) on 10-μm-thick frozen sagittal sections prepared from the P21 B6 mouse cerebellum using Pcdh-α3 (nucleotides 379–2362 according to GenBank™ accession number NM_138662), Pcdh-αC1 (nucleotides 28–2405 according to GenBank™ accession number NM_001003671), Pcdh-αC2 (nucleotides 63–2516 according to GenBank™ accession number NM_001003672), and Pcdh-α CP3 (nucleotides 2518–4559 according to GenBank™ accession number NM_138662), as templates to synthesize digoxigenin-11-UTP-labeled (Roche) cRNA probes. The Pcdh-α CP3 probe bound to the identical 3′-untranslated regions of Pcdh-α1 to 12, C1, C2, and 7/8 (JF1). Split Single-cell RT-PCR of Purkinje Cells—Split single-cell RT-PCR of Purkinje cells was carried out as described previously (13Esumi S. Kakazu N. Taguchi Y. Hirayama T. Sasaki A. Hirabayashi T. Koide T. Kitsukawa T. Hamada S. Yagi T. Nat. Genet. 2005; 37: 171-176Crossref PubMed Scopus (204) Google Scholar). In brief, single Purkinje cells were prepared from the cerebellum of the F1 mice from B6 female × JF1 male, at P21. The tissue was dissected and subjected to enzymatic digestion at 37 °C for 30 min in 10 ml of dissociation solution consisting of 90 units of papain (Worthington), 0.002% dl-cysteine HCl (Sigma), 0.05% DNase I (Sigma), 0.1% bovine serum albumin (Sigma), and 0.05% glucose (Nacalai Tesque). The digested tissue was spun for 8 min at 300 × g, and the pellet was resuspended in Dulbecco's modified Eagle's medium (Sigma). To remove debris, the cells were filtered through a 100-μm cell strainer (Falcon). Single Purkinje cells were picked up by glass capillary and placed in thin, 200-μl PCR tubes with 6 μl of RNase-free water in each tube. Complementary DNA was synthesized from single-cell samples after being primed with 40 pmol/reaction of each primer in a total volume of 10 μl, using 7.5 units of Thermoscript reverse transcriptase (Invitrogen) according to the manufacturer's at °C for The was by at °C for The from a single Purkinje cell were split into three PCR tubes as and used as a for the The PCR was performed using μl of single-cell μl of PCR μl of μl of each μl of 10 each primer μl of and μl of and the PCR of of min at °C and 30 of at °C and 10 min at The primer are in The PCR primer was on a in all of the variable exons and in The for RT-PCR were in different exons to by the of genomic The of each PCR was performed using μl of the PCR as a In each was using primer by of of 30 30 The were by subjected to using a DNA and on or The to the from which each PCR was The of monoallelic expression from biallelic expression was by using In Situ of the C-type in the Pcdh-α previously examined the expression of the Pcdh-α variable exons in Purkinje cells (13Esumi S. Kakazu N. Taguchi Y. Hirayama T. Sasaki A. Hirabayashi T. Koide T. Kitsukawa T. Hamada S. Yagi T. Nat. Genet. 2005; 37: 171-176Crossref PubMed Scopus (204) Google Scholar). The Pcdh-α cluster contains two of the C-type of variable exons, C1 and C2 Y. Koide T. Shiroishi T. Yagi T. Mol. Biol. Evol. 2005; 22: 1433-1443Crossref PubMed Scopus (16) Google Scholar, 15Takei Y. Hamada S. Senzaki K. Mutoh T. Sugino H. Yagi T. Genomics. 2001; 72: 321-330Crossref PubMed Scopus (18) Google Scholar). Therefore, we examined the expression of the C1 and C2 in individual Purkinje cells of the B6 mouse cerebellum using in situ hybridization the for the C1 and C2 variable exons all of the Purkinje cells the which may expression were for the C1 probe and for the C2 probe similar to that of the constant probe The expression pattern of Pcdh-α3 was different from that of the C1 and C2 variable exons the for Pcdh-α3 was but was in of Purkinje cells. These results suggested that Purkinje cell expressed C1 and C2 in to the expression of the Pcdh-α variable exons. of Pcdh-α C1 and C2 from of Pcdh-α1to in Single Purkinje examined the expression of the C1 and C2 variable exons in the Pcdh-α cluster. the C1 and C2 variable exons of the JF1 mouse strain and polymorphisms the B6 strain Using the Purkinje cells of P21 F1 mice from a B6 × JF1 we performed split single-cell RT-PCR Single Purkinje cells were picked up by glass Complementary DNA of Pcdh-α, and was synthesized from the single-cell samples in a same and the was into three tubes and subjected to PCR The of PCR was carried out for each and used for each Pcdh-α variable the Pcdh-α for Purkinje J. K. Neurosci. 1998; Full Text Full Text PDF PubMed Scopus Google and the single Purkinje cells all had a Pcdh-α variable exon PCR in at one of the three which were subjected to the Purkinje PCR the of the the cells were subjected to PCR all were for and that they were Purkinje cells. Purkinje cells had three of three PCR for at one of the Pcdh-α variable exons to with our previous results (13Esumi S. Kakazu N. Taguchi Y. Hirayama T. Sasaki A. Hirabayashi T. Koide T. Kitsukawa T. Hamada S. Yagi T. Nat. Genet. 2005; 37: 171-176Crossref PubMed Scopus (204) Google Scholar). In to three of three PCR of the cell showed one of three or two of three PCR in cell may the of the in that cells. cells were for C1 and C2 our in situ hybridization results and C2 showed PCR in all the C1 was in all three tubes and These results indicated that of the Purkinje cells expressed the C1 and C2 variable exons, which is different from the other Pcdh-α variable exons. each PCR was subjected to to three patterns of monoallelic expression of the monoallelic expression of the and biallelic expression. monoallelic expression pattern was found for of the 21 three of three for the Pcdh-α1 to variable exons The monoallelic expression pattern was found in the in cell in cell and in cell and in cell and in cell and in cell in cell and and in cell In the of isoforms in cell each PCR showed different suggesting that the was expressed biallelically and at a could a single biallelic were in one PCR three of three monoallelic expression be at N. H. A. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). at versus was a highly by analysis monoallelic and biallelic expression the expressed isoforms, were from the B6 and five from the JF1 Thus, allelic from the or was found in These previous results monoallelic and combinatorial expression of the Pcdh-α variable exons in Purkinje cells (13Esumi S. Kakazu N. Taguchi Y. Hirayama T. Sasaki A. Hirabayashi T. Koide T. Kitsukawa T. Hamada S. Yagi T. Nat. Genet. 2005; 37: 171-176Crossref PubMed Scopus (204) Google Scholar). the same we the allelic expression patterns of the C1 and C2 variable exons. expression patterns were found for of the three of three for the C2 variable For the C1 variable biallelic expression patterns were found for of the three of three cell showed a monoallelic expression but the was almost similar to the biallelic expression of the C1 variable These results in to the Pcdh-α1 to variable exons, the C-type variable exons in the Pcdh-α cluster were expressed biallelically in Purkinje of the B6 and JF1 as the of each Pcdh-α variable exon in the split single-cell RT-PCR analysis in Purkinje cells in a and of the C-type in the Pcdh-α and Pcdh-γ the results obtained for the C1 and C2 variable exons, the expression patterns of all five C-type variable exons in the Pcdh-α and Pcdh-γ clusters were in single Purkinje cells by split single-cell RT-PCR analysis The C-type variable exons in the Pcdh-α and Pcdh-γ clusters were expressed of 21 cells showed the C1 variable and all 21 cells showed the C2 to C5 variable exons. the allelic expression patterns were by the PCR expression patterns were commonly found for all five of the C-type variable exons in the Pcdh-α and Pcdh-γ biallelic expression was in of the three of three for the variable of for the variable 21 of 21 for the variable of for the variable and of for the variable These results that the C-type variable exons in the Pcdh-α and Pcdh-γ clusters were expressed and biallelically in Purkinje of the B6 and JF1 as the of each Pcdh-α and Pcdh-γ C4, and -γ C5 exons in the split single-cell RT-PCR analysis in Purkinje cells in a and of the Pcdh-α, Pcdh-γA, and Pcdh-γB in Purkinje allelic expression patterns of the Pcdh-γA and -γB variable exons in the Pcdh-γ cluster were to we polymorphisms of the Pcdh-γ variable exons the B6 and JF1 Pcdh-γ exons and of the variable exons and of the variable exons) were and expression patterns were using split single-cell RT-PCR analysis in single Purkinje cells and Among Purkinje cells showed the PCR of or in all three tubes These cells were used for allelic expression The other cells show PCR in all three of the 8 cells showed PCR and the other cells showed PCR in one or two expression patterns were found for all of the three of three for the Pcdh-γA and Pcdh-γB variable exons the expressed isoforms, were from the B6 and were from the JF1 allelic was found for the Pcdh-γA or Pcdh-γB variable exons. These results that the Pcdh-γA and Pcdh-γB variable exons were each in single Purkinje cells. and combinatorial expression patterns of distinct variable exons were also found for the Pcdh-γA and Pcdh-γB variable exons. with our previous these results indicated that each Purkinje cell both Pcdh-α and Pcdh-γ variable of the B6 and JF1 as the of each and exon in the split single-cell RT-PCR analysis in Purkinje cells in a we examined the of the Pcdh-α and Pcdh-γ variable exons in single Purkinje cells. The split single-cell RT-PCR analysis showed that each single Purkinje cell both Pcdh-α and Pcdh-γ variable exons Purkinje two of these cells expressed the variable exon from the B6 and two expressed from the JF1 These Purkinje cells expressed different of cell showed two of three results for the from the B6 and three of three for the could be distinguished are cell had two of three PCR results for expression and three of three for from the B6 In addition, one cell two of three PCR results for from the B6 two of three for from the JF1 and two of three for from the B6 showed three of three PCR results for from the B6 and three of three for and Thus, individual Purkinje cell could of the Pcdh-α, Pcdh-γA, and Pcdh-γB variable exons from different alleles, suggesting that more combinatorial diversity is by differential of Pcdh-α and -γ variable exons in single Purkinje cells in a Here we showed that the mouse Pcdh gene clusters contain both and biallelically expressed variable exons and that the Pcdh genes are expressed and within a single Purkinje cell. the Pcdh-α and Pcdh-γA and -γB variable exons were whereas the C-type variable exons in the Pcdh-α and Pcdh-γ clusters were biallelically of the C-type variable exons were expressed in all Purkinje cells of the P21 mouse This is with the in situ hybridization results reported previously M. M. K. R. Mol. Neurosci. 2005; PubMed Scopus Google Scholar). the other the Pcdh-α and Pcdh-γA and -γB variable exons were expressed and in single Purkinje cells of the P21 mouse The expression patterns of the Pcdh-α and Pcdh-γ gene clusters in the are in of the Pcdh-α and Pcdh-γ isoforms were expressed in individual Purkinje cells at whereas all of the C-type variable exons in the Pcdh-α and Pcdh-γ gene clusters were Our previous report and have that two of Pcdh-α were expressed from the Pcdh-α and all five of the C-type exons in Pcdh-α and Pcdh-γ were expressed The of Pcdh-γA and -γB be from the Among the Purkinje cells a the PCR in all three split tubes was found in cells for the genes and in 10 cells for the genes and exons were expressed Purkinje cell. are Pcdh-γA and Pcdh-γB variable exons in the gene cluster. Therefore, is of for we that of Pcdh-γA by and of Pcdh-γB by be expressed individual Purkinje cell. In of Pcdh-α, of Pcdh-γA, and Pcdh-γB be expressed in a Purkinje cell. In the Pcdh-α and Pcdh-γ × × × from Pcdh-α from each one from Pcdh-γA from each and one from Pcdh-γB from each in a single Purkinje cell. Therefore, these variable exons may diversity to different individual Purkinje cells. The showed that both the Pcdh-α and Pcdh-γ were expressed in the same Purkinje cell. It was previously reported that Pcdh-α and Pcdh-γ a which to the cell Pcdh-α is expressed on the cell of cells with Pcdh-α T. Hamada S. Senzaki K. Murata Y. Yagi T. Res. 2004; PubMed Scopus Google is cells are with both Pcdh-α and Pcdh-γ Y. Hamada S. Morishita H. Mutoh T. Yagi T. J. Biol. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). It that complex of Pcdh-α and Pcdh-γ may be on the cell of the Purkinje cells. to be the specificity of complex is different from that of the the of the complex on the cell may molecular diversity to and in the brain. It was previously that the expression patterns of the C-type Pcdh-α and Pcdh-γ are different from of the other variable exons during mouse brain The of Pcdh-α C1 and C2 at whereas of the other Pcdh-α exons at Y. Hamada S. Senzaki K. Mutoh T. Sugino H. Yagi T. Genomics. 2001; 72: 321-330Crossref PubMed Scopus (18) Google Scholar). M. M. K. R. Mol. Neurosci. 2005; PubMed Scopus Google Scholar) reported that the Pcdh-γ of and are expressed and at The transcript expression at but is in the transcript is the of the postnatal and M. M. K. R. Mol. Neurosci. 2005; PubMed Scopus Google Scholar). the by that the variable exon was more expressed than the This is with our results and our that the number of PCR in the split single-cell RT-PCR analysis the expression level. that the of C-type Pcdh-α and Pcdh-γ at different be that the C-type variable exons temporal diversity, and the Pcdh-α1 to and the Pcdh-γA and variable exons diversity for neuronal cell identity in the mouse brain. expression has been for genes. It is into five PubMed Scopus Google Scholar, Genet. PubMed Scopus Google genomic Cell. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar, Y. Nat. Genet. PubMed Scopus Google allelic K. PubMed Scopus Google Scholar, J. PubMed Scopus Google Scholar, A. H. R. Cell. Full Text PDF PubMed Scopus Google monoallelic and combinatorial and differential monoallelic expression. The S. K. S. 1998; PubMed Scopus Google S. K. S. 1998; PubMed Scopus Google Scholar, J.P. J. PubMed Scopus Google Scholar, R.M. 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J. 2000; PubMed Scopus Google Scholar). although the gene has a different and different exons from the the C-type Pcdh-α and Pcdh-γ variable exons have a distinct but and exons with other protocadherin genes in the same cluster Kim Y. Q. R. Maniatis T. Mol. Cell. Full Text Full Text PDF PubMed Scopus Google Scholar, H. A. Genes Dev. PubMed Scopus Google Scholar). It be to the of protocadherin which may a novel mechanism for the regulation of monoallelic gene expression. The showed that both the Pcdh-α and Pcdh-γ gene clusters contain and biallelically expressed genes. Our results that the Pcdh-α and Pcdh-γ gene clusters were generated by the of a gene and that the gene cluster both and biallelically expressed variable exons. at the mechanisms of expression of the protocadherin gene cluster be for the molecular mechanisms in generating the diversity of individual The of neuronal cell diversity by the of Pcdh-α and Pcdh-γ is to be as a molecular mechanism by which neuronal are in the vertebrate brain. T. Shiroishi for providing the JF1 strain and of the Yagi laboratory for and during the of with