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Biallelic Expression of the Gs Gene in Human Bone and Adipose Tissue

Institutes of Endocrine Sciences (G.M., S.B., C.P., A.G.L., E.F., M.F., P.B.-P., A.S.) and Neurological Sciences (M.L.), University of Milan, Ospedale Maggiore Istituto di Ricovero e Cura a Carattere Scientifico, 20122 Milan, Italy

Address all correspondence and requests for reprints to: Anna Spada, M.D., Istituto di Scienze Endocrine, Università di Milano, Padiglione Granelli, Via F. Sforza, 35, 20122 Milan, Italy. E-mail: anna.spada{at}unimi.it.

	Abstract

Top Abstract Introduction Patients and Methods Results and Discussion References

 
Mutations of the Gs gene inherited from the mother lead to pseudohypoparathyroidism (PHP) type Ia (PHP Ia), in which Albright’s hereditary osteodistrophy is associated to resistance to the action of different hormones, whereas the same mutations inherited from the father lead to isolated Albright’s hereditary osteodistrophy [pseudo-PHP (PPHP)]. Accordingly, it has been suggested that Gs is under tissue-specific imprinting control, and recent studies provided evidence for a predominant maternal origin of Gs transcripts in different endocrine organs involved in the PHP Ia phenotype. To establish whether Gs is imprinted also in tissues that are site of alteration both in PHP Ia and PPHP, we selected 20 bone and 10 adipose tissue samples, which were heterozygous for a known polymorphism in exon 5. Expression from both parental alleles was evaluated by RT-PCR and enzymatic digestion of the resulting fragments. By this approach, the great majority of the samples analyzed showed an equal expression of the two alleles. Our results provide evidence for the absence of Gs imprinting in human bone and fat and suggest that the clinical finding of osteodystrophy and obesity in PHP Ia and PPHP patients despite the presence of a normal Gs allele is likely due to Gs haploinsufficiency in these tissues.

	Introduction

Top Abstract Introduction Patients and Methods Results and Discussion References

 
PSEUDOHYPOPARATHYROIDISM (PHP) REFERS to a heterogeneous group of rare metabolic disorders characterized by hypocalcemia and hyperphosphatemia due to resistance to PTH (1, 2). Heterozygous loss of function mutations in stimulatory guanine nucleotide binding protein -subunit gene inherited from the mother lead to PHP type Ia (PHP Ia), a disease in which Albright’s hereditary osteodystrophy (AHO), a disorder characterized by a constellation of physical features (short stature, central obesity, round face, brachydactyly, and sc calcifications), is associated with end-organ resistance to the action of different hormones that activate Gs-coupled receptors, primarily PTH, TSH, gonadotropins, and GHRH (3, 4 ; reviewed in Refs.5, 6, 7 and at http://mammary.nih.gov/aho/). Interestingly, when the same mutations are inherited from the father, patients show the physical abnormalities of AHO, without evidence of hormone resistance [pseudo-PHP (PPHP)] (8, 9). This pattern of inheritance is consistent with a tissue-specific Gs paternal allele imprinting, an epigenetic phenomenon by which the paternal allele undergoes partial or total loss of expression (10, 11). The human Gs gene maps on chromosome 20q13, and there is increasing evidence that this locus is under complex imprinting control with multiple maternally, paternally, and biallelically alternatively spliced transcripts encoding multiple products (Fig. 1) (12, 13, 14, 15, 16). Considering the PHP Ia phenotype, Gs gene imprinting was predicted to be limited mainly to tissues, such as the renal proximal tubule, the thyroid, and the gonad, in which there is a parent-of-origin-specific difference in hormone responsiveness (17, 18, 19). Indeed, different authors have recently demonstrated that in the thyroid, the gonad and the pituitary Gs transcription mainly derives from the maternal allele (20, 21, 22, 23). On the contrary, organs affected in both PHP Ia and PPHP such as the bone and the adipose cells, whose differentiation has been demonstrated to be regulated by Gs activation and cAMP accumulation (24, 25, 26), would be expected to express the two alleles at the same extent.

View larger version (20K): [in this window] [in a new window]   FIG. 1. Genomic organization of human GNAS locus. The figure shows four alternative first exons that splice into exon 2, generating five different transcripts: Gs, NESP55, XLs, exon 1A, and an antisense transcript. Both the maternal and paternal alleles are shown. Arrows designate transcription start sites. The XLs, antisense, and 1A transcripts are expressed only from the paternal allele, whereas NESP55 is expressed specifically from the maternal allele. On the contrary, the Gs gene is biallelically expressed in most tissues, but it is predominantly expressed from the maternal allele in specific endocrine tissues such as the pituitary gland, the thyroid, and the gonad (20 21 22 ). The arrowhead marks the polymorphic FokI site in exon 5. Gray arrows indicate the position of primers used for RT-PCR.

	Patients and Methods

Top Abstract Introduction Patients and Methods Results and Discussion References

 
Tissues

The study included 23 normal flat-bone tissues obtained from patients undergoing neurosurgery treatment, 10 normal femoral tissues obtained from patients operated for thigh-bone fracture, and 22 visceral adipose tissue specimens from normal-weight patients undergoing abdominal surgery. The study also included femoral samples obtained from fetuses at 12, 16, and 26 wk gestation retrieved after legal voluntary termination or spontaneous intrauterine death. In all cases, the informed consent of the mother was obtained before procurement of the tissues, in accordance with guidelines outlined by the San Paolo Institute Ethics Committee.

As control, we used two pituitary samples that had been previously analyzed and in which the Gs gene had been demonstrated to be paternally imprinted (21). Informed consent was obtained in all cases by prior approval of the project by the local ethics committee.

PCR, semiquantitative RT-PCR, and digestions

DNA and RNA were extracted from all samples with standard methods. Exon 5 was amplified from genomic DNA by PCR using the primers and under the conditions described previously (27). The amplified products were then screened by digestion for a silent T to C polymorphism in exon 5 (28) that creates a FokI site (1 h at 37 C, with 1 U of enzyme). Heterozygosity for this polymorphism was then confirmed by direct sequencing (ABI-PRISM 310; PE Applied Biosystems, Foster City, CA).

To examine allele-specific gene expression, 1 µg total RNA was reverse transcribed (Promega, Madison, WI) and then subjected to PCR (28 cycles at 94/63/72 C for 45/45/45 sec) using a common downstream primer located in exon 6 (21), and three exon 1-specific upstream primers amplifying Gs (GenBank accession no. M21139 J03647, nucleotides 789–807), exon 1A (GenBank accession no. AF 246983, nucleotides 1692–1711), and NESP55 (GenBank accession no. AJ 251760, nucleotides 1432–1451) genes, respectively (Gs, 5'-CCATGGGCTGCCTCGGGAACA-3'; exon 1A, 5'-CCTTGCGTGTGAGTGCACCT-3'; and NESP55, 5'-AGCCCGAGGACAAAGATCCA-3').

The hypoxanthine-guanine phosphoribosyltransferase (HGPRT) gene was used as internal standard to verify and normalize template concentration. For each cDNA, preliminary experiments were conducted to determine the PCR cycles corresponding to the exponential phase, as previously described (27). RT-PCR products were digested with FokI as for genomic DNA and visualized on 2% Nusieve-1% agarose gels. Bands from Gs RT-PCR were finally evaluated by an imaging densitometer (GS-700; Bio-Rad Laboratories, Inc., Richmond, CA), and the maternal contribution was calculated as a percentage of the sum of the normalized values for the two alleles. Due to alternative splicing of exon 3, each Gs allele displays a double band, and the unspliced form (i.e. the upper band) was arbitrarily chosen for densitometric evaluation.

To rule out the presence of blood contamination, we evaluated the presence of two specific white blood cell antigens: CD14 and CD3 transcripts were amplified using intron-spanning primers in all our samples and visualized on agarose gel (primers and PCR conditions available on request).

	Results and Discussion

Top Abstract Introduction Patients and Methods Results and Discussion References

 
The evaluation of parental origin of transcription of the Gs gene was carried out on samples that were heterozygous for the polymorphism in exon 5: 12 flat bone, eight tubular bone (six adult and two fetal samples at 12 and 26 wk gestational age), and 10 adipose samples. The parental origin of Gs transcripts was established by FokI digestion and direct sequencing of NESP55 and exon 1A transcripts, and both analyses showed the expected monoallelic expression from opposite alleles, thus confirming the presence of an intact imprinting status in the samples investigated. In particular, when a NESP55-derived transcript was shown to carry the polymorphism, i.e. the correspondent band was digested by Fok1, the exon 1A-derived transcript from the same sample always displayed a wild-type sequence and was not digested by the same enzyme. With the exception of one flat-bone sample that displayed a slight predominance of the maternal allele over the paternal one (ratio of maternal to total x 100, 61%), all the examined tissues showed a similar expression of the Gs gene from the two alleles (ratio maternal to total x 100 ± SD, 53.2 ± 6.5%, P = not significant) (Fig. 2). No difference in allele-specific expression ratio was observed between flat and tubular bone, as well as between adult and fetal bone. Two pituitary samples were also investigated as a control of imprinted tissues (21). In these samples, although the Gs-derived transcripts were biallelically expressed, a significant predominant expression of the maternal allele over the paternal one was found (Fig. 2).

View larger version (35K): [in this window] [in a new window]   FIG. 2. To examine Gs allele-specific gene expression, RT-PCR products from specific amplifications of Gs, exon 1A, and NESP55 genes were digested with FokI, and the parental origin of Gs transcripts was established by observing the pattern of digestion of the maternally derived NESP55 transcript. The figure shows the expression of the Gs gene after 1-h digestion with FokI in three different adipose (A), four adult bone (B1 and B2, flat bones; B3 and B4, femoral bones), and two fetal bone (FB) samples that were found to be heterozygous for the polymorphism in exon 5. All samples displayed a comparable intensity of bands from the two alleles. In all cases, the study of the maternally derived NESP55 and the paternally derived exon 1A transcripts indicated the expected monoallelic expression. In particular, when a NESP-derived transcript was shown to carry the polymorphism, i.e. the correspondent band was digested by Fok1, the exon 1A-derived transcript from the same sample always displayed a wild-type sequence and was not digested by the same enzyme. Two pituitary samples (P) are included as an example of imprinted tissues. Gs-derived transcripts are biallelically expressed but show a significant predominant expression of the maternal allele over the paternal one, i.e. the most expressed allele is always the same represented in NESP55 transcripts. Uncut (U) control is also shown in the figure. Double bands seen in all samples are due to alternative splicing of exon 3, characteristic of all GNAS1 transcripts. In our study the unspliced form (i.e. the upper band) has been arbitrarily chosen for densitometric evaluation. The reciprocal amount of spliced and nonspliced Gs transcripts has been demonstrated to vary in different tissues and under different metabolic conditions, but the physiological significance of these changes is still a matter of debate.

Our study first demonstrates that, unlike specific endocrine tissues in which Gs transcription mainly derives from the maternal allele, human bone and fat tissues showed a biallelic expression of the gene, with an equal contribution from the maternal and the paternal alleles. Admittedly, other experimental approaches are needed to rule out the existence of a slight but still significant difference between maternal and paternal expression. These results are in part at variance with the data obtained in Gs (12) and, more recently, in exon 1A (29) knockout (KO) mice, in which imprinting of Gs paternal allele was observed in the adipose tissue. It is likely that these discrepant data may be due to either species differences (mouse vs. human) or experimental model (naturally occurring mutations vs. KO). However, it is worth noting that GsKO mice only in part recapitulate the human PHP Ia and PPHP phenotypes (12).

A recent report by our lab (21) demonstrated the presence of imprinting of Gs paternal allele in selective tissues, such as the thyroid, the pituitary, and the gonad, which, besides the kidney, are affected in PHP Ia patients (2, 3, 4), consistent with the notion that heterozygous loss-of-function mutations inherited from the mother lead to PHP type Ia phenotype. Moreover, the observation of a different extent of maternal contribution to Gs expression in thyroid and gonadal samples may explain why hypothyroidism is present in the totality of patients with PHP Ia, whereas hypogonadism is demonstrated in a lower percentage of cases. In agreement with the notion that patients with PHP Ia show a normal responsiveness to ACTH, both the paternal and maternal allele were equally expressed in the adrenal gland (21), thus justifying the occurrence of resistance to some (PTH, TSH, GHRH, and gonadotropins), but not all, hormones that activate Gs-coupled pathways in patients with PHP Ia.

We now provide additional data on the complex regulation of Gs expression in different organs that are involved in AHO phenotype. All patients with inactivating Gs mutations, independently of the maternal or paternal origin of the mutation, display osteodystrophy and central obesity. Several lines of evidence suggest that differentiation of these organs is, at least in part, regulated by the cAMP pathway. Gs activation inhibits the differentiation of osteoprogenitor cells to mature osteoblasts in a cAMP-dependent manner, and, conversely, decreased Gs expression leads to increased osteoblast differentiation (24). Similarly, Gs blockage promotes differentiation of preadipocytes to mature adipocytes, whereas ß-adrenergic agents induce the expression of uncoupling protein and increase the rate of thermogenesis (25, 26). Therefore, it is plausible that Gs deficiency in pluripotential cells might promote the formation of bone in heterotopic locations on one hand and lead to decreased energy expenditure in adipose tissue, thus resulting in obesity, on the other. Therefore, taking into consideration the absence of Gs gene imprinting in bone and adipose tissue reported here, it is tempting to speculate that the clinical finding of osteodystrophy and obesity in all PHP Ia and PPHP patients despite the presence of one normal Gs allele may be due to the presence of haploinsufficiency of this gene, at least in these tissues. Conversely, in most other tissues, the presence of 50% activity of the protein is predicted to be sufficient for a normal function (30).

Taken together, the data described herein strongly support the hypothesis that tissue-specific imprinting of the Gs gene is indeed the potential mechanism responsible for occurrence of variable resistance to hormone action in patients with PHP Ia and may explain the presence of some AHO features such as osteodystrophy and obesity in all patients carrying Gs mutations.

	Acknowledgments

 
We acknowledge the staff in the Department of Obstetrics and Gynaecology of San Paolo Hospital Medical School (University of Milan, Italy) for obtaining fetal samples.

	Footnotes

 
This work was partially supported by Ministero dell’Istruzione, dell’Università e della Ricerca Grant 2002068252 and by Ricerca Corrente Funds of Ospedale Maggiore Istituto di Ricovero e Cura a Carattere Scientifico (Milan, Italy).

Abbreviations: AHO, Albright’s hereditary osteodystrophy; KO, knockout; PHP, pseudohypoparathyroidism; PHP Ia, PHP type Ia; PPHP, pseudo-PHP.

Received March 23, 2004.

Accepted September 8, 2004.

	References

Top Abstract Introduction Patients and Methods Results and Discussion References

 

1. Albright F, Burnett CH, Smith PH, Parson W 1942 Pseudohypoparathyroidism-an example of "Seabright Bantam syndrome." Endocrinology 30:922–932
2. Weinstein LS 1998 Albright hereditary osteodystrophy, pseudohypoparathyroidism, and Gs deficiency. In: Spiegel AM, ed. G proteins, receptors, and disease. Totowa, NJ: Humana Press; 23–56.
3. Mantovani G, Maghnie M, Weber G, De Menis E, Brunelli V, Cappa M, Loli P, Beck-Peccoz P, Spada A 2003 GHRH resistance in pseudohypoparathyroidism type Ia: new evidence for imprinting of the Gs gene. J Clin Endocrinol Metab 88:4070–4074[Abstract/Free Full Text]
4. Germain-Lee EL, Groman J, Crane JL, Jan de Beur SM, Levine MA 2003 Growth hormone deficiency in pseudohypoparathyroidism type 1a: another manifestation of multihormone resistance. J Clin Endocrinol Metab 88:4059–4069[Abstract/Free Full Text]
5. Aldred MA, Trembath RC 2000 Activating and inactivating mutations in the human GNAS1 gene. Hum Mutat 16:183–189[CrossRef][Medline]
6. Weinstein LS, Yu S, Warner DR, Liu J 2001 Endocrine manifestations of stimulatory G protein -subunit mutations and the role of genomic imprinting. Endocr Rev 22:675–705[Abstract/Free Full Text]
7. Lania A, Mantovani G, Spada A 2001 G protein mutations in endocrine diseases. Eur J Endocrinol 145:543–559[Abstract]
8. Nakamoto JM, Sandstrom AT, Brickman AS, Christenson RA, Van Dop C 1998 Pseudohypoparthyroidism type Ia from maternal but not paternal transmission of a Gs gene mutation. Am J Med Genet 77:261–267[CrossRef][Medline]
9. Weinstein LS, Yu S 1999 The role of genomic imprinting of Gs in the pathogenesis of Albright’s hereditary osteodystrophy. Trends Endocrinol Metab 10:81–85[CrossRef][Medline]
10. Bartolomei MS, Tilgham SM 1997 Genomic imprinting in mammals. Annu Rev Genet 31:493–525[CrossRef][Medline]
11. Polychronakos C, Kukuvitis A 2002 Parental genomic imprinting in endocrinopathies. Eur J Endocrinol 147:561–569[Abstract]
12. Yu S, Yu D, Lee E, Eckhaus M, Lee R, Corria Z, Accili D, Westphal H, Weinstein LS 1998 Variable and tissue-specific hormone resistance in heterotrimeric Gs protein -subunit (Gs) knockout mice is due to tissue-specific imprinting of the Gs gene. Proc Natl Acad Sci USA 95:8715–8720[Abstract/Free Full Text]
13. Hayward BE, Kamiya M, Strain L, Moran V, Campbell R, Hayashizaki Y, Bonthron DT 1998 The human GNAS1 gene is imprinted and encodes distinct paternally and biallelically expressed G proteins. Proc Natl Acad Sci USA 95:10038–10043[Abstract/Free Full Text]
14. Hayward BE, Moran V, Strain L, Bonthron DT 1998 Bidirectional imprinting of a single gene: GNAS1 encodes maternally, paternally and biallelically derived proteins. Proc Natl Acad Sci USA 95:15475–15480[Abstract/Free Full Text]
15. Peters J, Wroe SF, Wells CA, Miller HJ, Bodle D, Beechey CV, Williamson CM, Kelsey G 1999 A cluster of oppositely imprinted transcripts at the Gnas locus in the distal imprinting region of mouse chromosome 2. Proc Natl Acad Sci USA 96:3830–3835[Abstract/Free Full Text]
16. Liu J, Yu S, Litman D, Chen W, Weinstein LS 2000 Identification of a methylation imprint mark within the mouse Gnas locus. Mol Cell Biol 20:5808–5817[Abstract/Free Full Text]
17. Farfel Z, Brickman AS, Kaslow HR, Kaslow VM, Bourne HR 1980 Defect of receptor-cyclase coupling protein in patients with pseudohypoparathyroidism. N Engl J Med 303:237–242[Abstract]
18. Levine MA, Downs Jr RW, Moses AM, Breslau NA, Marx SJ, Lasker RD, Rizzoli RE, Aurbach GD, Spiegel AM 1983 Resistance to multiple hormones in patients with pseudohypoparathyroidism: association with deficient activity of guanine nucleotide regulatory protein. Am J Med 74:545–556[CrossRef][Medline]
19. Levine MA, Downs RW, Singer M, Marx SJ, Aurbach GD, Spiegel AM 1980 Deficient activity of guanine nucleotide regulatory protein in erythrocytes from patients with pseudohypoparathyroidism. Biochem Biophys Res Commun 94:1319–1324[CrossRef][Medline]
20. Hayward BE, Barlier A, Korbonits M, Grossman AB, Jacquet P, Enjalbert A, Bonthron DT 2001 Imprinting of the Gs gene GNAS1 in the pathogenesis of acromegaly. J Clin Invest 107:R31–R36
21. Mantovani G, Ballare E, Giammona E, Beck-Peccoz P, Spada A 2002 The Gs gene: predominant maternal origin of transcription in human thyroid gland and gonads. J Clin Endocrinol Metab 87:4736–4740[Abstract/Free Full Text]
22. Germain-Lee EL, Ding CL, Deng Z, Crane JL, Saji M, Ringel MD, Levine MA 2002 Paternal imprinting of G(s) in the human thyroid as the basis of TSH resistance in pseudohypoparathyroidism type 1a. Biochem Biophys Res Commun 296:67–72[CrossRef][Medline]
23. Liu J, Erlichman B, Weinstein LS 2003 The stimulatory G protein -subunit Gs is imprinted in human thyroid glands: implications for thyroid function in pseudohypoparathyroidism types 1A and 1B. J Clin Endocrinol Metab 88:4336–4341[Abstract/Free Full Text]
24. Turksen K, Grogoriadis AE, Heersche JNM, Aubin JE 1990 Forskolin has biphasic effects on osteoprogenitor cell differentiation in vitro. J Cell Physiol 127:61–69
25. Wang H, Watkins DC, Malbon CC 1992 Antisense oligodeoxynucleotides to Gs () subunit sequence accelerate differentiation of fibroblasts to adipocytes. Nature 358:334–337[CrossRef][Medline]
26. Hamann A, Flier JS, Lowell BB 1996 Decreased brown fat markedly enhances susceptibility to diet-induced obesity, diabetes and hyperlipidemia. Endocrinology 137:21–29[Abstract]
27. Mantovani G, Romoli R, Weber G, Brunelli V, De Menis E, Beccio S, Beck-Peccoz P, Spada A 2000 Mutational analysis of GNAS1 in patients with pseudohypoparathyroidism: identification of two novel mutations. J Clin Endocrinol Metab 85:4243–4248[Abstract/Free Full Text]
28. Miric A, Vechio JD, Levine MA 1993 Heterogeneous mutations in the gene encoding the -subunit of the stimulatory G protein of adenylyl cyclase in Albright hereditary osteodystrophy. J Clin Endocrinol Metab 76:1560–1568[Abstract]
29. Williamson CM, Ball ST, Nottingham WT, Skinner JA, Plagge A, Turner MD, Powles N, Hough T, Papworth D, Fraser WD, Maconochie M, Peters J 2004 A cis-acting control region is required exclusively for the tissue-specific imprinting of Gnas. Nat Genet 36:894–899[CrossRef][Medline]
30. Levine MA, Jap TS, Mauseth RS, Downs RW, Spiegel AM 1986 Activity of the stimulatory guanine nucleotide-binding protein is reduced in erythrocytes from patients with pseudohypoparathyroidism and pseudopseudohypoparathyroidism: biochemical, endocrine and genetic analysis of Albright’s hereditary osteodystrophy in six kindreds. J Clin Endocrinol Metab 62:497–502[Abstract/Free Full Text]

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This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mantovani, G. Articles by Spada, A. Search for Related Content PubMed PubMed Citation Articles by Mantovani, G. Articles by Spada, A.