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Proceedings of the Society for Experimental Biology and Medicine 223:362-366 (2000)
© 2000 Society for Experimental Biology and Medicine

Original Article

Leptin Receptor Transcripts Are Constitutively Expressed in Placenta and Adipose Tissue with Advancing Baboon Pregnancy

Amy E. Green*,§, Jennifer S. O'neil*,§, Kenneth F. Swan*, Rudolf P. Bohm, Jr., Marion S. Ratterree and Michael C. Henson*,{dagger},{ddagger},§,¶,1


* Departments of Obstetrics/Gynecology,
{dagger} Physiology,
{ddagger} Anatomy, and
§ The Interdisciplinary Program of Molecular and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana 70112–2699; and
Tulane Regional Primate Research Center, Covington, Louisiana 70433–8915


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
The baboon (Papio sp.) is an accepted nonhuman primate model for the study of the endocrinology of human pregnancy. To further characterize this model with regard to leptin function, messenger RNA transcripts for both long (Ob-RL) and short (Ob-RS) leptin receptor isoforms were identified in maternal tissues at various stages of gestation. Thus, placental villous, subcutaneous and omental adipose tissues were collected upon cesarean delivery at early (Days 60–62), mid (Days 98–102) and late (Days 159–164) pregnancy (term {approx} 184 days). Additionally, amniochorion, decidua, and corpus luteum were collected in late gestation. Expression of Ob-RL and Ob-RS transcripts was determined in relation to constitutively expressed glyceraldehyde-3-phosphate dehydrogenase via reverse transcriptase-polymerase chain reaction, and transcripts were localized within specific placental cell types by in situ hybridization. Ob-RL and Ob-RS transcripts were present in amniochorion, decidua, and corpus luteum at term and appeared constitutively expressed throughout gestation in placenta and adipose tissues. Ob-RS was expressed in greater (P < 0.02) abundance than Ob-RL in all tissues. Within the placenta, receptor isoforms were localized predominantly to the syncytiotrophoblast. The expression of leptin receptor transcripts in maternal adipose tissues, as well as in the syncytiotrophoblast, amniochorion, decidua, and corpus luteum, suggests the potential for autocrine/paracrine roles for the polypeptide in the endocrinology of primate pregnancy. These are the first such observations in a nonhuman primate and support the use of the baboon as a model for the study of leptin in human pregnancy.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Leptin, a 16-kDa polypeptide produced by both adipocytes and the placenta, functions in the regulation of energy homeostasis via interaction with a specific hypothalamic receptor (1). Human leptin receptor transcripts have been identified in adipose tissue (2), placenta (3-5), and ovary (2, 6), suggesting that leptin may exert direct effects on a number of peripheral tissues. In the human placenta, leptin, Ob-RL, and Ob-RS transcripts have been localized to the syncytiotrophoblast, suggesting potential regulatory roles for the polypeptide in pregnancy (5). The leptin receptor is a member of the Cytokine Class 1 Receptor Superfamily and is homologous to the gp130 subunit of cytokine receptors, such as interleukin-6 (IL-6). It exists as five alternatively spliced isoforms, each differing in the length of their intracellular domains (7). The long isoform (Ob-RL) is detected predominantly in the weight-regulating regions of the hypothalamus and has a 302-amino acid intracellular domain, capable of signal transduction through the activation of Janus kinase and the signal transducers and activators of transcription (JAK/STAT). Three of the shorter isoforms, including Ob-RS, have cytoplasmic domains ranging from 32–40 amino acids and differential signaling capabilities, possibly involving mitogen activating protein kinase (MAPK) (8). Although the functions of the shorter isoforms have yet to be determined, they may be involved in either leptin transport across the blood-brain barrier or leptin clearance from the body, or they may act as circulating leptin binding proteins (7, 9).

The baboon (Papio sp.) is a proven model for the study of human pregnancy (10) and we have previously reported on the similarities in maternal leptin profiles between human (5) and baboon (11) pregnancy. Because the further development of animal models in which leptin regulation and function can be studied will prove valuable to a better understanding of leptin in human gestation, the goal of the current study was to characterize the ontogeny of leptin receptor transcripts with advancing baboon pregnancy.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Animals.
Baboons were maintained in accordance with USDA regulations and the Guide for the Care and Use of Laboratory Animals (NIH Publication 86–23). The experimental protocol was approved by the Institutional Care and Use Committee of the Tulane Regional Primate Research Center. Fifteen female baboons, weighing {approx} 14–17 kg, were individually housed in stainless steel cages. As we have previously described, a 12-hr photoperiod (0600–1800 hr) was maintained in air-conditioned rooms, and animals were fed a primate maintenance ration with fresh fruit daily and water provided ad libitum (11). Females were quartered with males for mating within indoor/outdoor enclosures (4–5 days) coinciding with the estimated occurrence of ovulation, as determined by daily menstrual cycle records and the observance of external sex skin turgescence (10-12).

Tissue Collection.
Baboon placental villous, amniochorion, decidua, corpus luteum, omental, and subcutaneous adipose tissues were collected at cesarean delivery under isofluorane anesthesia, as we have previously reported (11, 12). Tissues were obtained at early (60–62 days), mid (98–102 days) and late (159–167 days) gestation. Normal term in the baboon was {approx} 184 days. Samples designated as "early" were collected {approx} 30–35 days following the luteal-placental shift. Placental tissue was harvested from multiple villous trees and pooled for each animal, as we have previously described (13). Samples of abdominal subcutaneous adipose tissues were collected at the site of the initial abdominal incision, with samples of omental adipose tissues collected from the peritoneal cavity. Amniochorion, decidua, and corpus luteum were collected in late gestation. Tissue samples were flash-frozen in liquid nitrogen for storage at –80°C for reverse transcriptase-polymerase chain reaction (RT-PCR) or fixed in Histochoice (Amresco, Solon, OH) for in situ hybridization.

RNA Extraction and RT-PCR.
Total RNA was extracted from all tissues using TRIzol reagent (Life Technologies, Grand Island, NY) according to Chomczynski and Sacchi (14) as adapted in our laboratory (5). All samples were treated with DNase (Gibco, Life Technologies Inc., Gaithersburg, MD) to eliminate DNA contamination and reprecipitated with sodium acetate and 100% ethanol. Oligonucleotide primers were synthesized (Midland Reagent Company, Midland, TX) for Ob-RL (2), Ob-RS (15), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (5). Primer sequences, Genbank accession numbers, and PCR product sizes are listed in Table IGo. Sequence analysis of PCR products (Biotech Core, Palo Alto, CA) confirmed that primers specifically amplified regions of Ob-RL and Ob-RS complimentary DNAs (cDNA) (11). Complimentary DNAs were synthesized from 2 µg total RNA (placental, amniochorion, decidua, and corpus luteum) or 1 µg of total RNA (adipose tissues) using SuperScript Kit (Life Technologies), and PCR was performed in Temp-Tronic Thermocyclers (Barnstead/Thermolyne, Dubuque, IA) as we have previously described (5). Conditions for PCR were as follows: Ob-RL (32 cycles for amplification, denaturation at 94°C for 60 sec, annealing at 60°C for 60 sec, extension at 72°C for 90 sec) (2), Ob-RS (32 cycles for amplification, denaturation at 94°C for 30 sec, annealing at 51°C for 30 sec, extension at 72°C for 40 sec) (15), GAPDH (24 cycles for amplification, denaturation at 94°C for 30 sec, annealing at 58°C for 60 sec, extension at 72°C for 60 sec) (5). PCR products were viewed under UV light on 2% agarose gels with ethidium bromide. PCR reactions were accompanied by the following controls: GAPDH affirmed consistent cDNA synthesis; sterile water blanks served as a reagent control; and RNA that had not been transcribed into cDNA was used as a control for DNA contamination.


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  		Table I.   Sequences of Ob-RL (Long Isoform), Ob-RS (Short Isoform), and GAPDH Primers Used in RT-PCR
 
Linear ranges for each receptor isoform and GAPDH were determined to ensure that all reactions were analyzed during the exponential phase of amplification. Amplification efficiencies for each receptor isoform and GAPDH were found to be consistent between individual reactions, ensuring minimal interassay variability (16). Band intensities were analyzed using the Alpha Imager 2000 digital analysis system (Alpha Innotech, San Leandro, CA), as we have previously described (5, 11). Semiquantitative assessment of mRNA transcripts was made via a ratio between leptin receptor isoforms and GAPDH.

In Situ Hybridization.
Paraffin-embedded tissue sections (6 µm) were floated onto Superfrost Plus microscope slides (Labcraft, Fisher Scientific, Norwalk, GA). The slides were fixed overnight at 37°C and baked at 65°C prior to deparaffinization. In situ hybridization was performed using 5' biotinylated probes for both Ob-RL and Ob-RS, as we have described previously (5).

Statistical Analysis.
A one-way analysis of variance (ANOVA) and t-tests were performed to establish statistical significance between groups. Significant differences were understood to exist when P < 0.05.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Gestational Profile for Leptin Receptor Isoforms.
Ob-RL and Ob-RS expression was determined via RT-PCR in placental villous, amniochorion, decidua, corpus luteum, omental, and subcutaneous adipose tissues (Fig. 1)Go. Expression of Ob-RL and Ob-RS mRNA transcripts was semiquantitatively assessed through comparison with constitutively expressed GAPDH. No significant differences (P > 0.05) in Ob-RL or Ob-RS transcript abundance were observed as a consequence of advancing gestation in placenta, omental adipose tissue, or subcutaneous adipose tissue (Fig. 2)Go. Thus, both isoforms appear to be constitutively expressed throughout baboon pregnancy. Also as illustrated in Figure 2Go, Ob-RS transcripts were consistently expressed in greater abundance than Ob-RL transcripts in placenta (P < 0.002), omental adipose tissue (P < 0.02), and mid- and late subcutaneous adipose tissue (P < 0.01). There were no statistically significant differences between Ob-RS and Ob-RL in subcutaneous fat collected at the early time point.



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  		Figure 1.   Expression of Ob-RL and Ob-RS mRNA transcripts in peripheral tissues. Ob-RL (439 bp) and Ob-RS (573 bp) mRNA transcript expression was demonstrated by RT-PCR in placental villous tissue (P), amniochorion (AC), decidua (D), corpus luteum (CL), omental adipose tissue (OAT), and subcutaneous adipose tissue (SAT).

 


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  		Figure 2.   Ob-RL and Ob-RS mRNA transcripts in peripheral tissues. Ratios of band intensities of Ob-RL and Ob-RS receptor isoforms to GAPDH at early (Days 60–62), mid- (Days 98–102), and late (Days 159–167) gestation in (A) placental villous tissue [n = 5], (B) omental adipose tissue [n = 4], and (C) subcutaneous adipose tissue [n = 4]. Each bar represents the mean ± standard error. Open bars denote Ob-RL, and closed bars denote Ob-RS. Different lower-case letters denote statistically significant differences in transcript abundance: placental tissue (a compared with b, P < 0.002), omental adipose tissue (a compared with b, P < 0.02), subcutaneous adipose tissue (a compared with b, P < 0.01).

 
Placental Histology.
To determine specific cellular localization of Ob-RL and Ob-RS transcription, sections of placental villous tissue were evaluated by standard light microscopy and in situ hybridization. As depicted in Figure 3AGo, hematoxylin and eosin staining revealed multinucleated syncytiotrophoblasts surrounding placental villi (black arrowhead). Ob-RS and Ob-RL mRNA transcripts were predominantly expressed within the syncytiotrophoblast encasing the villous trees (Figs. 3B & 3C)Go. The 5' sense strand was used as a negative control for both receptor isoform hybridizations. Figure 3DGo is representative of a negative control, using the 5' sense strand for Ob-RL.



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  		Figure 3.   In situ hybridization of Ob-RL and Ob-RS in placenta. (A) Hematoxylin and eosin stain of villous placental tissue from early in gestation. The syncytiotrophoblast (black arrowhead) and the intravillous space (iv) are denoted. Positive in situ hybridization of (B) Ob-RS and (C) Ob-RL, using the 3' antisense mRNA. (D) In situ hybridization of Ob-RL using the 5' sense mRNA as a negative control.

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
The leptin receptor is a key component in the regulation of leptin action at the tissue level. Thus, leptin receptors are expressed in a variety of organs, and in vitro evidence suggests that, in addition to effects on the hypothalamus, leptin may also exert direct effects on a number of peripheral tissues, including the placenta (5), ovary (6), adrenal gland (15), and adipose tissue (17). Although a number of regulatory roles for leptin have been implied (1, 4, 11, 15, 18), little is known about leptin receptor ontogeny during primate pregnancy. Therefore, to more fully understand pregnancy as a unique physiological state that affects whole-body metabolism and energy expenditure, six distinct tissues were examined in the current study for expression of two signaling competent isoforms of the leptin receptor. The presence of both receptor isoforms in the placenta, amniochorion, decidua, corpus luteum, and adipose tissue attests to the potential significance of leptin as a reproductive hormone. Physiological roles for leptin at these peripheral sites are yet undefined, but we might hypothesize from our findings (5, 11) and those of others (19) that leptin has the potential to initiate, via receptor-mediated mechanisms, signaling cascades ultimately affecting placental endocrine function, conceptus growth, and/or the maternal hypothalamic-pituitary axis.

Although all tissue samples were collected after the luteal-placental shift, we report that long and short isoforms of the leptin receptor are constitutively expressed in placenta, as well as in two distinct adipose depots, throughout most of baboon pregnancy. This finding contrasts with a recent report, which documented an increase in placental leptin receptor mRNA transcripts with advancing gestation in the rat (20). However, certain differences may be inherent between primate and rat pregnancy. In this capacity, leptin transcripts may (21) or may not (22) be present in rat placenta, a feature that may be in contrast to both the baboon and the human, species that exhibit similar profiles for placental leptin mRNA transcripts during pregnancy (5, 11). Because of this and other reproductive similarities, we have proposed the baboon to be an excellent model for the study of leptin and leptin receptor biology during human pregnancy (11).

In the baboon, Ob-RS mRNA transcripts were expressed in greater abundance than Ob-RL, suggesting the potential for divergent signaling capacities. Leptin receptor signaling involves the dimerization of the cytoplasmic domains of the receptor chains. This action is essential for signal transduction and is proposed to bring JAKs, which are associated with intracellular motifs, into the necessary proximity for cross-phosphorylation and activation of their catalytic domains (23). Upon JAK activation, STAT proteins are recruited, dimerized, and translocated to the nucleus to modulate the transcription of target genes. Ob-RS and Ob-RL are the two most prominent isoforms of the leptin receptor, and they have differing signaling capabilities, reflected in the varying lengths of their intracellular domains. Ob-RL has a fully intact intracellular domain, which enables it to activate the JAK/STAT pathway, whereas Ob-RS is unable to recruit STAT proteins due to the absence of certain intracellular protein motifs (24). Despite this, Ob-RS still has the capacity to transduce signals through JAK or MAPK activation (8).

This study demonstrated a greater abundance of placental and adipose Ob-RS mRNA transcripts than Ob-RL, suggesting an increased presence of the membrane-bound shorter isoform. Precedent established from other homodimerizing cytokine receptors attests to strong dominant-negative repression, by dimerization, of inefficient signaling isoforms with signaling competent ones (25). This implies that Ob-RS may repress the signaling capacity of Ob-RL by forming a heterodimer. Despite this supposition, Ob-RL is only minimally affected by dominant negative repression by Ob-RS heterodimer formation (24, 26) and is capable of signal transduction in light of a greater abundance of Ob-RS (26). In peripheral tissues, Ob-RS, though incapable of activating STAT proteins, may be of greater importance than once thought in transducing leptin signals to the nucleus. The greater abundance of Ob-RS may facilitate an increased activation of other signaling pathways.

The syncytiotrophoblast is that portion of the placenta responsible for the manufacture of many of the steroid and polypeptide hormones normally associated with pregnancy in the human and nonhuman primate (10, 13). In the current study, two leptin receptor isoforms were localized to this cell population within the baboon placenta. Previously, we have identified transcripts for leptin in baboon syncytiotrophoblast (11), and both leptin and two leptin receptor isoforms in human syncytiotrophoblast (5). Collectively therefore our results suggest that leptin has the capacity to act in an autocrine/paracrine fashion within this endocrinologically active tissue. We also report that Ob-RL and Ob-RS mRNA transcripts are constitutively expressed in baboon placenta and adipose tissues, with Ob-RS expressed in relatively greater abundance. Both isoforms were also found to be expressed in amniochorion, decidua, and corpus luteum. This study further emphasizes the potential importance of leptin to regulatory mechanisms in the primate maternal-fetoplacental unit and to the utility of the baboon as an endocrine model for human pregnancy. However, further investigations are needed to address the physiological roles of leptin and its receptor throughout primate pregnancy.


   Footnotes
 
This work was supported by NIH Research Grant R29 HD32502 to M.C.H. and by P51 RR00164–35 to the Tulane Regional Primate Center. It was presented in part at the 32nd Annual Meeting of the Society for the Study of Reproduction.

1 To whom requests for reprints should be addressed at Tulane University School of Medicine, Department of Obstetrics and Gynecology, 1430 Tulane Avenue, New Orleans, LA 70112–2699. E-mail: michael.henson{at}tulane.edu Back


   References
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 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Mantzoros CS, Moschos SJ. Leptin: In search of role(s) in human physiology and pathophysiology. Clin Endocrinol 49:551–567, 1998.[Medline]
  2. Kielar D, Clark JSC, Ciechanowicz A, Kurzawski G, Sulikowski T, Naruszewicz M. Leptin receptor isoforms expressed in human adipose tissue. Metabolism 47:844–847, 1998.[Medline]
  3. Luoh S-M, Di Marco F, Levin N, Armanini M, Xie MH, Nelson C, Bennett GL, Williams M, Spencer SA, Gurney A, de Sauvage FJ. Cloning and characterization of a human leptin receptor using a biologically active leptin immunoadhesin. J Mol Endocrinol 18:77–85, 1997.[Abstract/Free Full Text]
  4. Cioffi JA, Shafer AW, Zupancic TJ, Smith-Gbur J, Mikhail A, Platika D, Snodgrass HR. Novel B219/OB receptor isoforms: Possible role of leptin in hematopoiesis and reproduction. Nat Med 2:585–589, 1996.[Medline]
  5. Henson MC, Swan KF, O'neil JS. Expression of placental leptin and leptin receptor transcripts in early pregnancy and at term. Obstet Gynecol 92:1020–1028, 1998.[Abstract]
  6. Karlsson C, Lindell K, Svensson E, Bergh C, Lind P, Billig H, Carlsson LMS, Carlsson B. Expression of functional leptin receptors in the human ovary. J Clin Endocrinol Metab 82:4144–4148, 1997.[Abstract/Free Full Text]
  7. Tartaglia LA. The leptin receptor. J Biol Chem 272:6093–6096, 1997.[Free Full Text]
  8. Bjørbæk C, Uotani S, da Silva B, Flier JS. Divergent signaling capacities of the long and short isoforms of the leptin receptor. J Biol Chem 272:32686–32695, 1997.[Abstract/Free Full Text]
  9. Lewandowski K, Horn R, O'callaghan CJ, Dunlop D, Medley GF, O'hare P, Brabant G. Free leptin, bound leptin, and soluble leptin receptor in normal and diabetic pregnancies. J Clin Endocrinol Metab 84:300–306, 1999.[Abstract/Free Full Text]
  10. Henson MC. Pregnancy maintenance and the regulation of placental progesterone biosynthesis in the baboon. Hum Reprod Update 4:389–405, 1998.[Abstract/Free Full Text]
  11. Henson MC, Castracane VD, O'neil JS, Gimpel T, Swan KF, Green AE, Shi W. Serum leptin concentrations and expression of leptin transcripts in placental trophoblast with advancing baboon pregnancy. J Clin Endocrinol Metab 84:2543–2549, 1999.[Abstract/Free Full Text]
  12. Henson MC, Greene SJ, Reggio BC, Shi W, Swan KF. Effects of reduced maternal lipoprotein-cholesterol availability on placental progesterone biosynthesis in the baboon. Endocrinology 138:1385–1397, 1997.[Abstract/Free Full Text]
  13. Henson MC, Shi W, Greene SJ, Reggio BC. Effects of pregnant human, nonpregnant human, and fetal bovine sera on human chorionic gonadotropin, estradiol, and progesterone release by cultured human trophoblast cells. Endocrinology 137:2067–2074, 1996.[Abstract]
  14. Chomczynski P, Sacchi N. Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem 162:156–159, 1997.
  15. Glasow A, Haidan A, Hilbers U, Breidert M, Gillespie J, Scherbaum WA, Chrousos GP, Bornstein SR. Expression of Ob receptor in normal human adrenals: Differential regulation of adrenocortical and adrenomedullary function by leptin. J Clin Endocrinol Metab 83:4459–4466, 1998.[Abstract/Free Full Text]
  16. Dufva M, Svenningsson A, Hansson GK. Differential regulation of macrophage scavenger receptor isoforms: mRNA quantification using the polymerase chain reaction. J Lipid Res 36:2282–2290, 1995.[Abstract]
  17. Siegrist-Kaiser CA, Pauli V, Juge-Aubry CE, Boss O, Pernin A, Chin WW, Cusin I, Rohner-Jeanrenaud F, Burger AG, Zapf J, Meier CA. Direct effects of leptin on brown and white adipose tissue. J Clin Invest 100:2858–2864, 1997.[Medline]
  18. Masuzaki H, Ogawa Y, Sagawa N, Hosoda K, Matsumoto T, Mise H, Nishimura H, Yoshimasa Y, Tanaka I, Mori T, Nakao K. Nonadipose tissue production of leptin: Leptin as a novel placenta-derived hormone in humans. Nat Med 3:1029–1033, 1997.[Medline]
  19. Clarke IJ, Henry BA. Leptin and reproduction. Rev Reprod 4:48–55, 1999.[Abstract]
  20. Kawai M, Murakami T, Otani S, Shima K, Yamaguchi M, Kishi K. Co-localization of leptin receptor (OB-R) mRNA and placental lactogen-II in rat trophoblast cells: Gestational profile of OB-R mRNA expression in placentae. Biochem Biophys Res Commun 257:425–430, 1999.[Medline]
  21. Amico JA, Thomas A, Crowley RS, Burmeister LA. Concentrations of leptin in the serum of pregnant, lactating, and cycling rats and of leptin messenger ribonucleic acid in rat placental tissue. Life Sci 63:1387–1395, 1998.[Medline]
  22. Kawai M, Yamaguchi M, Murakami T, Shima K, Murata Y, Kishi K. The placenta is not the main source of leptin production in pregnant rat: Gestational profile of leptin in plasma and adipose tissues. Biochem Biophys Res Commun 240:798–802, 1997.[Medline]
  23. Ihle JN, Kerr IM. JAKs and STATS in signaling by the cytokine receptor superfamily. TIG 11:69–74, 1995.
  24. White DW, Kuropatwinski KK, Devos R, Baumann H, Tartaglia LA. Leptin receptor (OB-R) signaling: Cytoplasmic domain mutational analysis and evidence for receptor homo-oligomerization. J Biol Chem 272:4065–4071, 1997.[Abstract/Free Full Text]
  25. Ross RJM, Esposito N, Shen XY, Von Laue S, Chew SL, Dobson PRM, Postel-Vinay M-C, Finidori J. A short isoform of the human growth hormone receptor functions as a dominant negative inhibitor of the full-length receptor and generates large amounts of binding protein. Mol Endocrinol 11:265–273, 1997.[Abstract/Free Full Text]
  26. White DW, Tartaglia LA. Evidence for ligand-independent homo-oligomerization of leptin receptor (OB-R) isoforms: A proposed mechanism permitting productive long-form signaling in the presence of excess short-form expression. J Cell Biochem 73:278–288, 1999.[Medline]
Received for publication September 14, 1999. Accepted for publication November 10, 1999.




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