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Comparative Analysis of BMPR2 Gene and Its Mutations in Idiopathic Pulmonary Arterial Hypertension
Comparative Analysis of BMPR2 Gene and Its Mutations in Idiopathic Pulmonary Arterial Hypertension* Wai P. K. Wong, PhD; James A. Knowles, MD, PhD; and Jane H. Morse, MD
(CHEST 2005; 128:615S) Abbreviation: IPAH ⫽ idiopathic pulmonary arterial hypertension
of the gene BMPR2 encoding the protein M utations bone morphogenetic protein receptor type II have
been found in the patients with familial and sporadic forms of idiopathic pulmonary arterial hypertension (IPAH). The BMPR2 gene belongs to the transforming growth factor- receptor protein family, which is a large family of different proteins that regulate normal cell growth. When the gene is mutated or becomes defective, it allows the vascular cells within the small pulmonary arteries to grow unregulated and block the blood vessels. The predicted protein structure of BMPR2 consists of extracellular ligand binding, transmembrane, kinase, and long cytoplasmic domains. In this study, we performed a comparative sequence analysis of BMPR2 from diverse vertebrates and invertebrates. We found that the protein kinase domain exhibited an overall high degree of conservation (85 to 99% identity in vertebrates), while the extracellular domain and the long cytoplasmic tail with largely unknown function were more divergent. However, within the cytoplasmic tail, we identified several highly conserved regions, including a 44-amino acid prolineglutamic acid-serine-threonine motif, which were likely to represent functional or structural subdomains. In addition, comparison of human, mouse, and zebra fish BMPR2 exons revealed an increased rate of nonsynonymous nucleotide substitutions in exons 12 and 13, which encoded most of the cytoplasmic tail, compared to the other exons. This finding suggested that the cytoplasmic tail may have evolved under different functional constraints. Furthermore, the distribution of IPAH-associated mutations and neutral polymorphisms suggested that IPAH-associated missense mutations occurred at highly conserved residues while polymorphisms were in regions of lower conservation. Remarkably, almost all of the 20 missense mutations occurred at nucleotides and *From the Department of Medicine, Department of Psychiatry, Columbia Genome Center, Columbia University College of Physicians and Surgeons and the New York State Psychiatric Institute, New York, NY. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml). Correspondence to: James A. Knowles, MD, PhD, Associate Professor of Clinical Psychiatry, Columbia University College of Physicians and Surgeons, Columbia Genome Center, New York State Psychiatric Institute, 1051 Riverside Dr, Room 5916, Unit 28, New York, NY 10032; e-mail [email protected] www.chestjournal.org
amino acids that were identical across all species studied. Taken together, these data identified the regions of the BMPR2 gene that may be critical for its normal function. 1286December2005
Ventilation/Perfusion Ratios in Pulmonary Arterial Hypertension* Effects of IV and Inhaled Prostacyclin Derivatives Tomas Bratel, MD; Lars Lagerstrand, MD; Lars-Åke Brodin, MD; Jacek Nowak, MD; and Ivar Randmaa, MD
(CHEST 2005; 128:615S– 616S) Abbreviations: log SDQ ⫽ SD of the distribution of perfusion; PVR ⫽ pulmonary vascular resistance; Svo2 ⫽ venous oxygen ˙ ⫽ ventilation/perfusion saturation; V˙/Q
nine patients with severe pulmonary arterial hyperI ntension (one primary and the others secondary to
systemic sclerosis or pulmonary embolism), ventilation/ ˙ ) ratios were measured during right-heart perfusion (V˙/Q catheterization using a multiple inert gas elimination ˙ ratios were assessed before and after technique. V˙/Q administration of IV epoprostanol, 8.5 ⫾ 1.8 ng/kg/min. Following 5.1 ⫾ 1.5 months of inhaled iloprost therapy ˙ ratios were again measured before and 15 (20 g tid), V˙/Q min after inhalation of 20 g of iloprost. Before treatment, mean (⫾ SD) pulmonary artery pressure was 46.2 ⫾ 13.5 mm Hg. Pulmonary vascular resistance (PVR) was 8.61 ⫾ 4.52 mm Hg/L/min, and cardiac output was 4.22 ⫾ 0.75 L/min. There was a moderately elevated shunt of 5.1% (range, 1.6 to 19.5%) of cardiac output and ˙ ventilation of 8.1% of minute ventisubstantial high V˙/Q lation (range, 2.9 to 36.8%), and increased dispersion of ˙ ratios (SD of the perfusion and ventilation for the V˙/Q distribution of perfusion [log SDQ], 0.93 ⫾ 0.31; and SD of the distribution of ventilation, 08 ⫾ 0.23). Epoprostanol infusion resulted in a 21 ⫾ 18% reduction in PVR and a 36 ⫾ 14% reduction in systemic vascular resistance. log SDQ was further increased by 30 ⫾ 33%. The mean increase in shunt was approximately 60% higher during epoprostanol than after iloprost (p ⫽ 0.06). However, due to increased cardiac output and raised venous oxygen saturation (Svo2), Pao2 was not significantly altered. *From the Department of Pulmonary Diseases (Dr. Bratel), Karolinska Hospital, Karolinska; and Department of Clinical Physiology (Drs. Lagerstrand, Brodin, Nowak, and Randmaa), Huddinge University Hospital, Stockholm, Sweden. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml). Correspondence to: Tomas Bratel, MD, Department of Pulmonary Diseases, Karolinska Hospital, Karolinska, Sweden CHEST / 128 / 6 / DECEMBER, 2005 SUPPLEMENT
615S
(CHEST 2005; 128:615S) Abbreviation: IPAH ⫽ idiopathic pulmonary arterial hypertension
of the gene BMPR2 encoding the protein M utations bone morphogenetic protein receptor type II have
been found in the patients with familial and sporadic forms of idiopathic pulmonary arterial hypertension (IPAH). The BMPR2 gene belongs to the transforming growth factor- receptor protein family, which is a large family of different proteins that regulate normal cell growth. When the gene is mutated or becomes defective, it allows the vascular cells within the small pulmonary arteries to grow unregulated and block the blood vessels. The predicted protein structure of BMPR2 consists of extracellular ligand binding, transmembrane, kinase, and long cytoplasmic domains. In this study, we performed a comparative sequence analysis of BMPR2 from diverse vertebrates and invertebrates. We found that the protein kinase domain exhibited an overall high degree of conservation (85 to 99% identity in vertebrates), while the extracellular domain and the long cytoplasmic tail with largely unknown function were more divergent. However, within the cytoplasmic tail, we identified several highly conserved regions, including a 44-amino acid prolineglutamic acid-serine-threonine motif, which were likely to represent functional or structural subdomains. In addition, comparison of human, mouse, and zebra fish BMPR2 exons revealed an increased rate of nonsynonymous nucleotide substitutions in exons 12 and 13, which encoded most of the cytoplasmic tail, compared to the other exons. This finding suggested that the cytoplasmic tail may have evolved under different functional constraints. Furthermore, the distribution of IPAH-associated mutations and neutral polymorphisms suggested that IPAH-associated missense mutations occurred at highly conserved residues while polymorphisms were in regions of lower conservation. Remarkably, almost all of the 20 missense mutations occurred at nucleotides and *From the Department of Medicine, Department of Psychiatry, Columbia Genome Center, Columbia University College of Physicians and Surgeons and the New York State Psychiatric Institute, New York, NY. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml). Correspondence to: James A. Knowles, MD, PhD, Associate Professor of Clinical Psychiatry, Columbia University College of Physicians and Surgeons, Columbia Genome Center, New York State Psychiatric Institute, 1051 Riverside Dr, Room 5916, Unit 28, New York, NY 10032; e-mail [email protected] www.chestjournal.org
amino acids that were identical across all species studied. Taken together, these data identified the regions of the BMPR2 gene that may be critical for its normal function. 1286December2005
Ventilation/Perfusion Ratios in Pulmonary Arterial Hypertension* Effects of IV and Inhaled Prostacyclin Derivatives Tomas Bratel, MD; Lars Lagerstrand, MD; Lars-Åke Brodin, MD; Jacek Nowak, MD; and Ivar Randmaa, MD
(CHEST 2005; 128:615S– 616S) Abbreviations: log SDQ ⫽ SD of the distribution of perfusion; PVR ⫽ pulmonary vascular resistance; Svo2 ⫽ venous oxygen ˙ ⫽ ventilation/perfusion saturation; V˙/Q
nine patients with severe pulmonary arterial hyperI ntension (one primary and the others secondary to
systemic sclerosis or pulmonary embolism), ventilation/ ˙ ) ratios were measured during right-heart perfusion (V˙/Q catheterization using a multiple inert gas elimination ˙ ratios were assessed before and after technique. V˙/Q administration of IV epoprostanol, 8.5 ⫾ 1.8 ng/kg/min. Following 5.1 ⫾ 1.5 months of inhaled iloprost therapy ˙ ratios were again measured before and 15 (20 g tid), V˙/Q min after inhalation of 20 g of iloprost. Before treatment, mean (⫾ SD) pulmonary artery pressure was 46.2 ⫾ 13.5 mm Hg. Pulmonary vascular resistance (PVR) was 8.61 ⫾ 4.52 mm Hg/L/min, and cardiac output was 4.22 ⫾ 0.75 L/min. There was a moderately elevated shunt of 5.1% (range, 1.6 to 19.5%) of cardiac output and ˙ ventilation of 8.1% of minute ventisubstantial high V˙/Q lation (range, 2.9 to 36.8%), and increased dispersion of ˙ ratios (SD of the perfusion and ventilation for the V˙/Q distribution of perfusion [log SDQ], 0.93 ⫾ 0.31; and SD of the distribution of ventilation, 08 ⫾ 0.23). Epoprostanol infusion resulted in a 21 ⫾ 18% reduction in PVR and a 36 ⫾ 14% reduction in systemic vascular resistance. log SDQ was further increased by 30 ⫾ 33%. The mean increase in shunt was approximately 60% higher during epoprostanol than after iloprost (p ⫽ 0.06). However, due to increased cardiac output and raised venous oxygen saturation (Svo2), Pao2 was not significantly altered. *From the Department of Pulmonary Diseases (Dr. Bratel), Karolinska Hospital, Karolinska; and Department of Clinical Physiology (Drs. Lagerstrand, Brodin, Nowak, and Randmaa), Huddinge University Hospital, Stockholm, Sweden. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml). Correspondence to: Tomas Bratel, MD, Department of Pulmonary Diseases, Karolinska Hospital, Karolinska, Sweden CHEST / 128 / 6 / DECEMBER, 2005 SUPPLEMENT
615S