Characterization of Argonaute-containing protein complexes in Leishmania-infected human macrophages.

The intracellular protozoan parasite Leishmania causes leishmaniasis in humans, leading to serious illness and death in tropical and subtropical areas worldwide. Unfortunately, due to the unavailability of approved vaccines for humans and the limited efficacy of available drugs, leishmaniasis is on the rise. A comprehensive understanding of host-pathogen interactions at the molecular level could pave the way to counter leishmaniasis. There is growing evidence that several intracellular pathogens target RNA interference (RNAi) pathways in host cells to facilitate their persistence. The core elements of the RNAi system are complexes of Argonaute (Ago) proteins with small non-coding RNAs, also known as RNA-induced silencing complexes (RISCs). Recently, we have shown that Leishmania modulates Ago1 protein of host macrophages for its survival. In this study, we biochemically characterize the Ago proteins' interactome in Leishmania-infected macrophages compared to non-infected cells. For this, a quantitative proteomic approach using stable isotope labelling by amino acids in cell culture (SILAC) was employed, followed by purification of host Ago-complexes using a short TNRC6 protein-derived peptide fused to glutathione S-transferase beads as an affinity matrix. Proteomic-based detailed biochemical analysis revealed Leishmania modulated host macrophage RISC composition during infection. This analysis identified 51 Ago-interacting proteins with a broad range of biological activities. Strikingly, Leishmania proteins were detected as part of host Ago-containing complexes in infected cells. Our results present the first report of comprehensive quantitative proteomics of Ago-containing complexes isolated from Leishmania-infected macrophages and suggest targeting the effector complex of host RNAi machinery. Additionally, these results expand knowledge of RISC in the context of host-pathogen interactions in parasitology in general.

Intensive care risk and long-term outcomes in pediatric allogeneic hematopoietic cell transplant recipients.

ABSTRACT: Allogeneic hematopoietic cell transplantation (HCT) can be complicated by life-threatening organ toxicity and infection necessitating intensive care. Epidemiologic data have been limited by single-center studies, poor database granularity, and a lack of long-term survivors. To identify contemporary trends in intensive care unit (ICU) use and long-term outcomes, we merged data from the Center for International Blood and Marrow Transplant Research and the Virtual Pediatric Systems databases. We identified 6995 pediatric patients with HCT aged ≤21 years who underwent first allogeneic HCT between 2008 and 2014 across 69 centers in the United States or Canada and followed patients until the year 2020. ICU admission was required for 1067 patients (8.3% by day +100, 12.8% by 1 year, and 15.3% by 5 years after HCT), and was linked to demographic background, pretransplant organ toxicity, allograft type and HLA-match, and the development of graft-versus-host disease or malignancy relapse. Survival to ICU discharge was 85.7%, but more than half of ICU survivors required ICU readmission, leading to 52.5% and 42.6% survival at 1- and 5-years post-ICU transfer, respectively. ICU survival was worse among patients with malignant disease, poor pretransplant organ function, and alloreactivity risk factors. Among 1-year HCT survivors, those who required ICU in the first year had 10% lower survival at 5 years and developed new dialysis-dependent renal failure at a greater rate (P<.001). Thus, although ICU management is common and survival to ICU discharge is high, ongoing complications necessitate recurrent ICU admission and lead to a poor 1-year outcome in select patients who are at high risk.

Leishmania infection upregulates and engages host macrophage Argonaute 1, and system-wide proteomics reveals Argonaute 1-dependent host response.

Leishmania donovani, an intracellular protozoan parasite, is the causative agent of visceral leishmaniasis, the most severe form of leishmaniasis in humans. It is becoming increasingly clear that several intracellular pathogens target host cell RNA interference (RNAi) pathways to promote their survival. Complexes of Argonaute proteins with small RNAs are core components of the RNAi. In this study, we investigated the potential role of host macrophage Argonautes in Leishmania pathogenesis. Using Western blot analysis of Leishmania donovani-infected macrophages, we show here that Leishmania infection selectively increased the abundance of host Argonaute 1 (Ago1). This increased abundance of Ago1 in infected cells also resulted in higher levels of Ago1 in active Ago-complexes, suggesting the preferred use of Ago1 in RNAi in Leishmania-infected cells. This analysis used a short trinucleotide repeat containing 6 (TNRC6)/glycine-tryptophan repeat protein (GW182) protein-derived peptide fused to Glutathione S-transferase as an affinity matrix to capture mature Ago-small RNAs complexes from the cytosol of non-infected and Leishmania-infected cells. Furthermore, Ago1 silencing significantly reduced intracellular survival of Leishmania, demonstrating that Ago1 is essential for Leishmania pathogenesis. To investigate the role of host Ago1 in Leishmania pathogenesis, a quantitative whole proteome approach was employed, which showed that expression of several previously reported Leishmania pathogenesis-related proteins was dependent on the level of macrophage Ago1. Together, these findings identify Ago1 as the preferred Argonaute of RNAi machinery in infected cells and a novel and essential virulence factor by proxy that promotes Leishmania survival.

Critical Illness Risk and Long-Term Outcomes Following Intensive Care in Pediatric Hematopoietic Cell Transplant Recipients.

Background: Allogeneic hematopoietic cell transplantation (HCT) can be complicated by the development of organ toxicity and infection necessitating intensive care. Risk factors for intensive care admission are unclear due to heterogeneity across centers, and long-term outcome data after intensive care are sparse due to a historical paucity of survivors. Methods: The Center for International Blood and Marrow Transplant Research (CIBMTR) was queried to identify patients age ≤21 years who underwent a 1st allogeneic HCT between 2008-2014 in the United States or Canada. Records were cross-referenced with the Virtual Pediatric Systems pediatric ICU database to identify intensive care admissions. CIBMTR follow-up data were collected through the year 2020. Result: We identified 6,995 pediatric HCT patients from 69 HCT centers, of whom 1,067 required post-HCT intensive care. The cumulative incidence of PICU admission was 8.3% at day +100, 12.8% at 1 year, and 15.3% at 5 years post HCT. PICU admission was linked to younger age, lower median zip code income, Black or multiracial background, pre-transplant organ toxicity, pre-transplant CMV seropositivity, use of umbilical cord blood and/or HLA-mismatched allografts, and the development of post-HCT graft-versus-host disease or malignancy relapse. Among PICU patients, survival to ICU discharge was 85.7% but more than half of ICU survivors were readmitted to a PICU during the study interval. Overall survival from the time of 1st PICU admission was 52.5% at 1 year and 42.6% at 5 years. Long-term post-ICU survival was worse among patients with malignant disease (particularly if relapsed), as well as those with poor pre-transplant organ function and alloreactivity risk-factors. In a landmark analysis of all 1-year HCT survivors, those who required intensive care in the first year had 10% lower survival at 5 years (77.1% vs. 87.0%, p<0.001) and developed new dialysis-dependent renal failure at a greater rate (p<0.001). Conclusions: Intensive care management is common in pediatric HCT patients. Survival to ICU discharge is high, but ongoing complications necessitate recurrent ICU admission and lead to a poor 1-year outcome in many patients. Together, these data suggest an ongoing burden of toxicity in pediatric HCT patients that continues to limit long-term survival.

Review of Lasers and Energy-Based Devices for Skin Rejuvenation and Scar Treatment With Histologic Correlations.

BACKGROUND: Lasers and energy-based devices (EBD) are popular treatments for skin rejuvenation and resurfacing. Achieving desired outcomes and avoiding complications require understanding the effects of these devices at a histologic level. Currently, no comprehensive review summarizing the histologic effects of laser and energy-based treatments exists. OBJECTIVE: To describe how lasers and EBD alter skin histology and improve the overall understanding of these devices. MATERIALS AND METHODS: A PubMed search was conducted for studies with histologic analysis of fractional picosecond laser, fractional radiofrequency microneedling, nonablative lasers, and ablative lasers. RESULTS: Fractional picosecond lasers induce intraepidermal and/or dermal vacuoles from laser-induced optical breakdown. Fractional radiofrequency microneedling delivers thermal energy to the dermis while sparing the epidermis, making it safer for patients with darker skin phototypes. Fractional nonablative lasers induce conical zones of coagulation of the epidermis and upper dermis. Ablative lasers vaporize the stratum corneum down to the dermis. Traditional ablative lasers cause diffuse vaporization while fractional ablative lasers generate columns of tissue ablation. CONCLUSION: Lasers and EBD are effective for skin resurfacing and rejuvenation and have different mechanisms with disparate targets in the skin. Safe and effective use of devices requires understanding the histologic laser-tissue interaction.

Systemic comorbidities of rosacea: practice gaps among dermatologists.

Rosacea is a chronic inflammatory skin condition that is associated with multiple systemic comorbidities, with the strongest evidence linking rosacea to hypertension, dyslipidemia, inflammatory bowel disease, and anxiety and depression. To assess dermatologists' awareness of and screening practices for rosacea comorbidities, we developed a survey that was distributed to attendings and residents across four academic dermatology departments in Massachusetts. A total of 73 dermatologists with varying experience participated in the study. Findings demonstrated significant knowledge and practice gaps among academic dermatologists in managing systemic comorbidities in rosacea. In addition, dermatologists' awareness of rosacea comorbidities was negatively correlated with number of years out of residency training, highlighting the need to address this knowledge gap through increased continuing medical education. Importantly, we observed a low screening frequency despite a high awareness of the association between rosacea and ocular comorbidities, suggesting that additional financial, institutional, or practice barriers likely contribute to the low screening rate.

Non-invasive prenatal sequencing for multiple Mendelian monogenic disorders using circulating cell-free fetal DNA.

Current non-invasive prenatal screening is targeted toward the detection of chromosomal abnormalities in the fetus1,2. However, screening for many dominant monogenic disorders associated with de novo mutations is not available, despite their relatively high incidence3. Here we report on the development and validation of, and early clinical experience with, a new approach for non-invasive prenatal sequencing for a panel of causative genes for frequent dominant monogenic diseases. Cell-free DNA (cfDNA) extracted from maternal plasma was barcoded, enriched, and then analyzed by next-generation sequencing (NGS) for targeted regions. Low-level fetal variants were identified by a statistical analysis adjusted for NGS read count and fetal fraction. Pathogenic or likely pathogenic variants were confirmed by a secondary amplicon-based test on cfDNA. Clinical tests were performed on 422 pregnancies with or without abnormal ultrasound findings or family history. Follow-up studies on cases with available outcome results confirmed 20 true-positive, 127 true-negative, zero false-positive, and zero-false negative results. The initial clinical study demonstrated that this non-invasive test can provide valuable molecular information for the detection of a wide spectrum of dominant monogenic diseases, complementing current screening for aneuploidies or carrier screening for recessive disorders.

Pleomorphic dermal sarcoma in a man with HIV: report with next-generation sequencing analysis and review of the atypical fibroxanthoma/pleomorphic dermal sarcoma spectrum.

Atypical fibroxanthoma (AFX) is a rare cutaneous fibrohistiocytic tumor that typically arises on chronically sun-damaged skin, such as the head and neck, as a nondescript ulcerated papule, nodule, or tumor. The clinical prognosis is usually favorable and metastasis is rare. Pleomorphic dermal sarcoma (PDS), or undifferentiated pleomorphic sarcoma, is a recently introduced diagnostic moniker for AFX-like tumors with more aggressive clinical and histologic features such as necrosis and vascular invasion. The exact relationship between AFX and PDS has been debated. Diagnosis of these tumors is generally based on immunohistochemical staining to exclude other mimics. A wholly specific marker for this tumor does not exist, leading to diagnostic ambiguity in certain cases. Herein, we present a case of pleomorphic dermal sarcoma in a 53-year-old man with human immunodeficiency virus that displayed patchy S100 staining concerning for melanoma upon hospital pathology review. Next-generation sequencing analysis confirmed a mutation pattern consistent with published molecular signatures of AFX/PDS. In discussing this case, we review the current understanding of AFX/PDS and discuss diagnostic pitfalls, as well as emphasize on how next-generation sequencing techniques might improve accuracy in the diagnosis of tumors in the spectrum of AFX/PDS.

Miransertib (ARQ 092), an orally-available, selective Akt inhibitor is effective against Leishmania.

Leishmaniasis is amongst the most important neglected diseases, afflicting more than 12 million people in 88 countries. There is an urgent need for safe orally bioavailable and cost-effective drugs for the treatment of leishmaniasis. It has recently been shown that Leishmania activates host macrophage serine/threonine kinase Akt, to promote survival of both parasites and infected cells. Here, we sought to evaluate a compound, Miransertib (ARQ 092), an orally bioavailable and selective allosteric Akt inhibitor currently in clinical trials for patients with PI3K/Akt-driven tumors or Proteus syndrome. Miransertib was tested against Leishmania donovani and Leishmania amazonensis, causative agents of visceral and cutaneous leishmaniasis, respectively. Cultured promastigotes were susceptible to Miransertib. In addition, Miransertib was markedly effective against intracellular amastigotes of L. donovani or L. amazonensis-infected macrophages. Miransertib also enhanced mTOR dependent autophagy in Leishmania-infected macrophages, which may represent one mechanism of Miransertib-mediated killing of intracellular Leishmania. Whereas parasite clearance in the spleen of mice infected with L. donovani and treated with Miransertib was comparable to that when treated with miltefosine, Miransertib caused a greater reduction in the parasite load in the liver. In the cutaneous leishmaniasis infection model, lesions were reduced by 40% as compared to mock treated mice. Together, these results provide direct evidence to support the conclusion that Miransertib is an excellent lead compound for the development of a new oral drug therapy for visceral and cutaneous leishmaniasis.

Basal Cell Carcinoma with Osteoma Cutis.

Osteoma cutis is the formation of bone within the skin. It can present as either primary osteoma cutis or secondary osteoma cutis. Secondary osteoma cutis is more common and is associated with inflammatory, infectious, and neoplastic disorders, including basal cell carcinoma. A 79-year-old Caucasian man without underlying kidney disease or calcium abnormalities presented with a basal cell carcinoma with osteoma cutis on the chin. Basal cell carcinoma with osteoma cutis has seldom been described; however, the occurrence of this phenomenon may be more common than suggested by the currently published literature. The preferred treatment is surgical excision-with or without using Mohs micrographic technique. When the histopathologic examination reveals bone formation in the skin, clinicians should consider the possible presence of an adjacent malignancy, such as a basal cell carcinoma.

De Novo Missense Variants in TRAF7 Cause Developmental Delay, Congenital Anomalies, and Dysmorphic Features.

TRAF7 is a multi-functional protein involved in diverse signaling pathways and cellular processes. The phenotypic consequence of germline TRAF7 variants remains unclear. Here we report missense variants in TRAF7 in seven unrelated individuals referred for clinical exome sequencing. The seven individuals share substantial phenotypic overlap, with developmental delay, congenital heart defects, limb and digital anomalies, and dysmorphic features emerging as key unifying features. The identified variants are de novo in six individuals and comprise four distinct missense changes, including a c.1964G>A (p.Arg655Gln) variant that is recurrent in four individuals. These variants affect evolutionarily conserved amino acids and are located in key functional domains. Gene-specific mutation rate analysis showed that the occurrence of the de novo variants in TRAF7 (p = 2.6 × 10-3) and the recurrent de novo c.1964G>A (p.Arg655Gln) variant (p = 1.9 × 10-8) in our exome cohort was unlikely to have occurred by chance. In vitro analyses of the observed TRAF7 mutations showed reduced ERK1/2 phosphorylation. Our findings suggest that missense mutations in TRAF7 are associated with a multisystem disorder and provide evidence of a role for TRAF7 in human development.

Edema Bullae Mimicking Disseminated Herpes Zoster.

Edema bullae typically forms at the site of skin swelling during acute states of volume overload, most commonly during renal or cardiac failure. Herpes zoster is a reactivation of latent varicella zoster virus that typically presents as painful vesicles in a dermatomal distribution. In immunocompromised individuals, disseminated herpes zoster skin manifestations may occur with several lesions in multiple dermatomes or widespread individual lesions or both, even visceral organs can be involved. Additionally, many conditions are known to mimic the lesions and distribution of herpes zoster. A 53-year-old immunosuppressed male with a history of renal transplant presented with dermatomal and non-dermatomal, disseminated herpes zoster that was confirmed by polymerase chain reaction testing. After one week of intravenous antiviral therapy during which his virus infection-associated lesions were resolved, new blisters developed near the insertion site of a peripheral venous line located on a previously uninvolved yet swollen upper extremity. The varicella zoster virus disease was initially suspected, but lab studies and skin biopsy of a blister excluded progressive or persistent viral infection and established a diagnosis of acute edema bullae. The blisters resolved following removal of the peripheral catheter. Acute edema bullae should be added to the list of mimickers of disseminated varicella zoster virus infection.

Erythrodermic Psoriasis in a Man with Monoclonal B-cell Lymphocytosis.

Erythroderma is characterized by erythema involving greater than 90% of the body surface area and may be caused by several etiologies, including erythrodermic psoriasis. Psoriasis is an autoimmune skin and systemic condition characterized by erythematous and scaly plaques. Monoclonal B-cell lymphocytosis is an asymptomatic hematological disorder diagnosed by elevated, small, clonal B-cell counts in the peripheral blood. The characteristics of a 71-year-old man with new onset of erythrodermic psoriasis and concurrent monoclonal B-cell lymphocytosis are presented. The simultaneous development of these two conditions raises the possibility that they may share a related pathogenesis.

A Comprehensive Strategy for Accurate Mutation Detection of the Highly Homologous PMS2.

Germline mutations in the DNA mismatch repair gene PMS2 underlie the cancer susceptibility syndrome, Lynch syndrome. However, accurate molecular testing of PMS2 is complicated by a large number of highly homologous sequences. To establish a comprehensive approach for mutation detection of PMS2, we have designed a strategy combining targeted capture next-generation sequencing (NGS), multiplex ligation-dependent probe amplification, and long-range PCR followed by NGS to simultaneously detect point mutations and copy number changes of PMS2. Exonic deletions (E2 to E9, E5 to E9, E8, E10, E14, and E1 to E15), duplications (E11 to E12), and a nonsense mutation, p.S22*, were identified. Traditional multiplex ligation-dependent probe amplification and Sanger sequencing approaches cannot differentiate the origin of the exonic deletions in the 3' region when PMS2 and PMS2CL share identical sequences as a result of gene conversion. Our approach allows unambiguous identification of mutations in the active gene with a straightforward long-range-PCR/NGS method. Breakpoint analysis of multiple samples revealed that recurrent exon 14 deletions are mediated by homologous Alu sequences. Our comprehensive approach provides a reliable tool for accurate molecular analysis of genes containing multiple copies of highly homologous sequences and should improve PMS2 molecular analysis for patients with Lynch syndrome.

Hydrogen sulfide suppresses oxidized low-density lipoprotein (ox-LDL)-stimulated monocyte chemoattractant protein 1 generation from macrophages via the nuclear factor κB (NF-κB) pathway.

This study was designed to examine the role of hydrogen sulfide (H2S) in the generation of oxidized low-density lipoprotein (ox-LDL)-stimulated monocyte chemoattractant protein 1 (MCP-1) from macrophages and possible mechanisms. THP-1 cells and RAW macrophages were pretreated with sodium hydrosulfide (NaHS) and hexyl acrylate and then treated with ox-LDL. The results showed that ox-LDL treatment down-regulated the H2S/cystathionine-ß-synthase pathway, with increased MCP-1 protein and mRNA expression in both THP-1 cells and RAW macrophages. Hexyl acrylate promoted ox-LDL-induced inflammation, whereas the H2S donor NaHS inhibited it. NaHS markedly suppressed NF-κB p65 phosphorylation, nuclear translocation, DNA binding activity, and recruitment to the MCP-1 promoter in ox-LDL-treated macrophages. Furthermore, NaHS decreased the ratio of free thiol groups in p65, whereas the thiol reductant DTT reversed the inhibiting effect of H2S on the p65 DNA binding activity. Most importantly, site-specific mutation of cysteine 38 to serine in p65 abolished the effect of H2S on the sulfhydration of NF-κB and ox-LDL-induced NF-κB activation. These results suggested that endogenous H2S inhibited ox-LDL-induced macrophage inflammation by suppressing NF-κB p65 phosphorylation, nuclear translocation, DNA binding activity, and recruitment to the MCP-1 promoter. The sulfhydration of free thiol group on cysteine 38 in p65 served as a molecular mechanism by which H2S inhibited NF-κB pathway activation in ox-LDL-induced macrophage inflammation.

LIN28 binds messenger RNAs at GGAGA motifs and regulates splicing factor abundance.

LIN28 is a conserved RNA-binding protein implicated in pluripotency, reprogramming, and oncogenesis. It was previously shown to act primarily by blocking let-7 microRNA (miRNA) biogenesis, but here we elucidate distinct roles of LIN28 regulation via its direct messenger RNA (mRNA) targets. Through crosslinking and immunoprecipitation coupled with high-throughput sequencing (CLIP-seq) in human embryonic stem cells and somatic cells expressing exogenous LIN28, we have defined discrete LIN28-binding sites in a quarter of human transcripts. These sites revealed that LIN28 binds to GGAGA sequences enriched within loop structures in mRNAs, reminiscent of its interaction with let-7 miRNA precursors. Among LIN28 mRNA targets, we found evidence for LIN28 autoregulation and also direct but differing effects on the protein abundance of splicing regulators in somatic and pluripotent stem cells. Splicing-sensitive microarrays demonstrated that exogenous LIN28 expression causes widespread downstream alternative splicing changes. These findings identify important regulatory functions of LIN28 via direct mRNA interactions.

Endogenous generation of sulfur dioxide in rat tissues.

While sulfur dioxide (SO(2)) has been previously known for its toxicological effects, it is now known to be produced endogenously in mammals from sulfur-containing amino acid L-cysteine. L-cysteine is catalyzed by cysteine dioxygenase (CDO) to L-cysteinesulfinate, which converts to ß-sulfinylpyruvate through transamination by aspartate aminotransferase (AAT), and finally spontaneously decomposes to pyruvate and SO(2). The present study explored endogenous SO(2) production, and AAT and CDO distribution in different rat tissue. SO(2) content was highest in stomach, followed by tissues in the right ventricle, left ventricle, cerebral gray matter, pancreas, lung, cerebral white matter, renal medulla, spleen, renal cortex and liver. AAT activity and AAT1 mRNA expression were highest in the left ventricle, while AAT1 protein expression was highest in the right ventricle. AAT2 and CDO mRNA expressions were both highest in liver tissue. AAT2 protein expression was highest in the renal medulla, but CDO protein expression was highest in liver tissue. In all tissues, AAT1 and AAT2 were mainly distributed in the cytoplasm rather than the nucleus. These observed differences among tissues endogenously generating SO(2) and associated enzymes are important in implicating the discovery of SO(2) as a novel endogenous signaling molecule.

Effects of sulfur dioxide on hypoxic pulmonary vascular structural remodeling.

Hypoxic pulmonary hypertension is a pathophysiological process important in the development of various cardiopulmonary diseases. Recently, we found that sulfur dioxide could be produced endogenously by pulmonary vessels, and that it showed vascular regulatory capabilities. In this paper, we examined the role of sulfur dioxide in hypoxic pulmonary vascular structural remodeling (HPVSR). A total of 48 Wistar rats were divided into six groups. Rats in the hypoxic group, hypoxic+sulfur dioxide group, and hypoxic+hydroxamate group were left under hypoxic conditions, whereas the control group, control+sulfur dioxide group, and control+hydroxamate group rats were left in room air. For each group, we measured the pulmonary arterial pressure, sulfur dioxide content in plasma and lung tissue, glutamate oxaloacetate transaminase 1 and 2 mRNAs, micro- and ultra-structural changes in pulmonary arteries, proliferation of pulmonary smooth muscle cells, vascular collagen metabolism, pulmonary endothelial cell inflammatory response, and pulmonary vascular endothelin-1 production in the rats. In hypoxic rats, the content of sulfur dioxide in plasma and lung tissue decreased significantly in comparison with those in the control groups, and significant pulmonary hypertension, pulmonary vascular structural remodeling, and increased vascular inflammatory response were also observed in hypoxic rats. Sulfur dioxide donor significantly downregulated Raf-1, mitogen-activated protein kinase kinase-1 (MEK-1) and p-ERK/ERK, and inhibited pulmonary vascular smooth muscle cell proliferation, collagen remodeling and pulmonary vascular endothelial cell nuclear factor-kappaB (NF-kappaB), and intercellular adhesion molecule 1 (ICAM-1) expressions. It also prevented pulmonary hypertension and pulmonary vascular structural remodeling in association with the upregulated sulfur dioxide/glutamate oxaloacetate transaminase pathway. Hydroxamate, however, advanced pulmonary hypertension, pulmonary vascular structural remodeling, and inflammatory response of the pulmonary artery in association with a downregulated sulfur dioxide/glutamate oxaloacetate transaminase pathway. The results suggested that sulfur dioxide markedly inhibited Raf-1, MEK-1, and the phosphorylation of extracellular signal-regulated kinase (ERK), and then inhibited pulmonary arterial smooth muscle cell (PASMC) proliferation induced by hypoxia. The downregulated sulfur dioxide/glutamate oxaloacetate transaminase pathway may be involved in the mechanisms responsible for pulmonary hypertension and pulmonary vascular structural remodeling.