Association between protein arginine N-methyltransferase 1 polymorphism and overt diabetic nephropathy: Role of asymmetric dimethylarginine in vascular tone.

Background: ω-NG,NG-asymmetric dimethylarginine (ADMA) regulates vascular tone and may participate in the pathogenesis of diabetic nephropathy (DN). Objective: To investigate whether single-nucleotide polymorphisms (SNPs) around the protein arginine N-methyltransferase 1 gene (PRMT1) influence ADMA dynamics and DN incidence and severity. Methods: This study utilized a hospital-based database containing 310 Japanese patients with type 2 diabetes mellitus (T2DM). The association of PRMT1-related tagged SNPs with DN stage distribution was examined using a dominant model of minor alleles. PRMT1 mRNA, serum ADMA, reactive hyperemia-peripheral arterial tonometry index (RHI), and brachial-ankle pulse wave velocity (baPWV) were compared between the genotype-based subgroups of causal SNP, and correlations between these variables were evaluated. Results: The composition of DN stages significantly differed between the GG and GA + AA subgroups of rs892151 (p = 0.026). In a propensity-matching cohort of rs892151, the GA + AA subgroup had an increased incidence of overt DN (odds ratio 2.92, 95 % confidence interval 1.12-7.62, p = 0.028), along with higher PRMT1 mRNA, serum ADMA levels, and baPWV than the GG subgroup (p < 0.001, p = 0.023 and 0.047, respectively). There were correlations between PRMT1 mRNA and serum ADMA levels, between serum ADMA levels and RHI, and between baPWV and urinary albumin excretion (r = 0.335, p < 0.001, r = -0.221, p = 0.029, and r = 0.254, p = 0.004, respectively). Conclusions: T2DM patients carrying the PRMT1-related variant rs892151 were susceptible to overt DN. ADMA-mediated endothelial dysfunction and arterial stiffness may be involved in the variant-related pathogenesis of overt DN.

Elderly-onset calcinosis of hyperphosphataemic familial tumoural calcinosis/hyperostosis-hyperphosphataemia syndrome: the role of comorbid scleroderma.

Summary: A 73-year-old woman with type 2 diabetes mellitus was referred to our department for glycaemic control. Physical examination revealed two subcutaneous hard masses around the left shoulder and the right hip joint. The patient could not fully extend her fingers because of skin sclerosis in both hands. Laboratory studies showed hyperphosphataemia and a high ratio of renal tubular maximum reabsorption of phosphate to glomerular filtration rate. There were no abnormalities in serum calcium, creatinine, alkaline phosphatase, and intact parathyroid hormone levels, whereas serum fibroblast growth factor 23 was low. Hyperphosphataemic familial tumoural calcinosis/hyperostosis-hyperphosphataemia syndrome (HFTC/HHS) was diagnosed using whole genome sequencing that revealed a novel frameshift beyond the 584th threonine located in the lectin domain of UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 3 associated with a duplication of the 1748th thymine in the coding region of the corresponding gene. Furthermore, anti-nuclear, anti-centromere, and anti-cardiolipin antibodies were positive, implying that comorbid limited type scleroderma might play a role in tumoural calcinosis (TC) development. A low phosphate diet was prescribed with phosphate-lowering medications, including aluminium hydroxide, acetazolamide, and sevelamer hydrochloride. The patient displayed a decrease in serum phosphate levels from 6.5 to 5.5 mg/dL 10 months after the initiation of treatment, but her TC had not improved during treatment for more than 1 year. This case was interesting because the patient with HFTC/HHS exhibited TC despite being over her 60s, and subsequent scleroderma might contribute to the specific clinical course. When HFTC/HHS presents with elderly-onset TC, the involvement of comorbidities in exacerbating TC should be considered. Learning points: HFTC/HHS occurs on an autosomal recessive basis, but its clinical course and manifestations differ significantly throughout the cases. HFTC/HHS may be undiagnosed until later in life because of its rarity, unfamiliarity, and phenotype diversity; therefore, HFTC/HHS should be included in the differential diagnosis of elderly patients with unexplained hyperphosphataemia or ectopic calcinosis. Comorbidities, including rheumatologic disorders, may contribute to developing HFTC/HHS-associated calcinosis.

Diabetic ketoacidosis-associated gangrenous ischaemic colitis masquerading as acute pancreatitis and differentiated using computed tomography.

Diagnosis of an acute abdomen during an episode of diabetic ketoacidosis (DKA) is crucial for providing appropriate treatments and obtaining favourable outcomes, but may be difficult due to its considerable overlap with multiple intra-abdominal diseases in terms of clinical course and laboratory findings. In this study, we presented a case showing signs of an acute abdomen with sharp rises in serum pancreatic biochemical markers during the treatment of DKA with pyelonephritis. Contrast-enhanced computed tomography (CT) was performed to confirm the onset of acute pancreatitis; however, pneumatosis intestinalis and poor enhancement of the rectal wall were detected, indicating the presence of rectal infarction. Hartmann's procedure was immediately performed, and histological examination of the resected specimen revealed gangrenous ischaemic colitis. The present case highlights DKA as a risk factor of ischaemic colitis and the role of contrast-enhanced CT in the differential diagnosis of an acute abdomen in hyperglycaemic crisis.

Protein arginine N-methyltransferase 1 gene polymorphism is associated with proliferative diabetic retinopathy in a Japanese population.

AIMS: To investigate the effects of single-nucleotide polymorphisms (SNPs) around the protein arginine N-methyltransferase 1 (PRMT1) gene on the incidence and severity of diabetic retinopathy (DR). METHODS: A total of 310 Japanese patients with type 2 diabetes mellitus (T2DM) were investigated. Genotyping of ten tagged SNPs were performed by quantitative real-time polymerase chain reaction (qRT-PCR). The association between each SNP genotype and diabetic microangiopathy was assessed using univariate analysis in a dominant model of the minor alleles followed by multivariate logistic regression analysis with the propensity score matching (PSM) method. The effect of disease-related SNP on PRMT1 and hypoxia-inducible factor-1α (HIF-1α) mRNA levels in vivo was evaluated by qRT-PCR. RESULTS: In the univariate analysis, the minor A allele at rs374569 and the minor C allele at rs3745468 were associated with DR severity (P = 0.047 and P = 0.003, respectively), but not diabetic nephropathy and peripheral polyneuropathy severity. Multivariate analysis showed that the rs3745468 variant caused an increased incidence of proliferative DR (PDR) (odds ratio 9.37, 95% confidence interval 1.12-78.0, P = 0.039). In the PSM cohort, the patients carrying the rs3745468 variant had lower PRMT1 mRNA levels compared to those without the variant (P = 0.037), and there was an inverse correlation between PRMT1 and HIF-1α mRNA levels (r = -0.233, P = 0.035). CONCLUSIONS: The rs3745468 variant in the PRMT1 gene was associated with an increased incidence of PDR in Japanese patients with T2DM and might be involved in the HIF-1-dependent hypoxic pathway through altered PRMT1 levels.

Remitting seronegative symmetrical synovitis with pitting oedema after surgical remission of Cushing's syndrome.

A 64-year-old woman with refractory cellulitis in the lower legs was referred for inadequate glycaemic control. Physical examination revealed cushingoid features including central obesity. CT of the abdomen revealed a right adrenal mass that was positive on 131I-adosterol imaging. Findings on endocrine evaluation confirmed a diagnosis of Cushing's syndrome, which was cured with a right adrenalectomy. Two months after surgery, the patient complained of pain and marked swelling of the hands during hydrocortisone replacement therapy (20 mg per day) given for postoperative adrenal insufficiency. Laboratory examination was unremarkable. However, contrast-enhanced T2-weighted MRI of the hands revealed enhanced signals surrounding the flexor tendons, leading to a diagnosis of remitting seronegative symmetrical synovitis with pitting oedema. Prednisolone (15 mg per day) was then initiated, and the symptoms disappeared within a few days. This case illustrates the possibility that successful treatment of Cushing's syndrome may trigger emergence of a glucocorticoid-responsive disease.

Appropriate indices for color rendition and their recommended values for UHDTV production using white LED lighting.

We selected appropriate indices for color rendition and determined their recommended values for ultra-high-definition television (UHDTV) production using white LED lighting. Since the spectral sensitivities of UHDTV cameras can be designed to approximate the ideal spectral sensitivities of UHDTV colorimetry, they have more accurate color reproduction than HDTV cameras, and thus the color-rendering properties of the lighting are critical. Comparing images taken under white LEDs with conventional color rendering indices (Ra, R9-14) and recently proposed methods for evaluating color rendition of CQS, TM-30, Qa, and SSI, we found the combination of Ra and R9 appropriate. For white LED lighting, Ra ≥ 90 and R9 ≥ 80 are recommended for UHDTV production.

Onset of Graves' disease during long-term immunosuppressive therapy in a patient with membranous nephropathy.

UNLABELLED: A 67-year-old man was referred to our department for thyrotoxicosis with intermittent palpitation and 4-kg weight loss during the previous month. At the first visit, the patient was treated with cyclosporine A (CyA) for membranous nephropathy during the last 3 years and 8 months. Laboratory studies revealed that the serum TSH level was <0.005 µU/ml, and free thyroxine (fT4) and triiodothyronine (fT3) levels were elevated at 2.76 ng/dl and 5.96 pg/ml respectively. Anti-TSH receptor antibody (TRAb) level was increased at 26.4%. A clinical diagnosis of Graves' hyperthyroidism was given, and then thyrostatic treatment with thiamazole (MMI) at a dose of 10 mg daily was initiated after CyA withdrawal. After the initiation of MMI therapy, serum fT4 and fT3 attained the normal level within 1.5 months, with relief of symptoms followed by a remarkable decrease in urinary protein excretion from 2.0-5.2 g/day to ≤0.03 g/day. The patient maintained euthyroid with a low titre of TRAb for the succeeding 2 years and then MMI was finally stopped. Neither a relapse of hyperthyroidism nor a flare-up of nephrotic syndrome was observed for 3 years after MMI discontinuation. CyA has conflicting effects on immunologic self-tolerance by modulation of self-reactive T cells and natural CD4(+)CD25(+)Foxp3(+) regulatory T cell (Treg) functions, and possibly becomes a triggering factor in the development of autoimmune disorders. This case may be interesting when considering the effect of each T cell subset on the development of Graves' disease. LEARNING POINTS: The balance between intrathyroidal self-reactive T cell and natural CD4(+)CD25(+)Foxp3(+) Treg functions determine self-tolerance in the thyroid.CyA not only halts the expansion of self-reactive T cells but also impairs the function of Treg, which can provoke an unwanted immune response.A change in thyroid autoimmunity during treatment with CyA may result in the development of autoimmune thyroid diseases (AITD).Renal involvement in AITD frequently manifests as nephrotic syndrome, and thyrostatic treatment with thiamazole may be effective for excessive proteinuria.

Reversible alterations in cardiac morphology and functions in a patient with Cushing's syndrome.

UNLABELLED: A 45-year-old female was referred for endocrine evaluation of an incidental mass (31×24 mm in diameter) on the right adrenal gland. The patient was normotensive and nondiabetic, and had no history of generalised obesity (body weight, 46 kg at 20 years of age and 51.2 kg on admission); however, her waist-to-hip ratio was 0.97. Elevated urinary free cortisol levels (112-118 µg/day) and other findings indicated adrenocorticotrophic hormone-independent Cushing's syndrome due to right adrenocortical adenoma. Echocardiography before adrenalectomy revealed concentric left ventricular (LV) hypertrophy with a particular increase in interventricular septum thickness leading to impaired systolic and diastolic functions. Upon surgical remission of hypercortisolism, the asymmetric hypertrophy disappeared and the cardiac dysfunctions were considerably ameliorated. Although the mechanism(s) by which excessive cortisol contributes to LV wall thickness remain(s) unclear, serial echocardiography and cardiac multidetector-row computed tomography may support the notion that abnormal fat deposition in the myocardium owing to hypercortisolism appears to be an important factor for the reversible change in the cardiac morphology. LEARNING POINTS: Patients with Cushing's syndrome occasionally exhibit severe LV hypertrophy related to systolic and diastolic dysfunctions although they have neither hypertension nor diabetes mellitus.Biological remission of hypercortisolism can normalise structural and functional cardiac parameters and help in differentiating the cardiac alterations induced by excessive cortisol from those induced by other diseases.Excessive lipid accumulation within the heart before myocardial fibrosis may be implicated in reversible alterations in the cardiac morphology by Cushing's syndrome.Early diagnosis and treatment of Cushing's syndrome appear to be pivotal in preventing irreversible cardiac dysfunctions subsequent to cardiovascular events and heart failure.

A case of Wilson's disease with characteristic laparoscopic findings.

A 44-year-old male was pointed out liver function abnormality by medical check-up. Blood examination and computed tomography showed liver cirrhosis. Then, he was referred to our hospital for further examination. After blood test, viral markers revealed previous infection of hepatitis B virus (HBV). We estimated the etiology of his liver disease as previous HBV infection. On laparoscopic examination, his liver surface was nodular with mixed yellowish nodules and ash gray to copper-colored nodules in the diameter of 3-10 mm. There were large regenerative nodules in segments 3 and 4. Large regenerative nodules and irregular steatosis were contradictory to HBV-related liver cirrhosis, so then we supposed Wilson's disease. The amount of copper excretion in the urine was 326.6 µg (>100 µg/24 h). After D-penicillamine administration, urinary copper excretion increased to 2151.5 µg/24 h. Though hepatic copper concentration was 174.5 µg/g wet tissue (>200 µg/g wet tissue), his laboratory data fulfilled the Leipzig diagnostic criteria proposed by EASL. Laparoscopic examination with liver biopsy has advantages to survey many disease-specific findings on liver surface and to obtain adequate liver sample. Laparoscopic examination is one of the effective procedures for diagnosing relatively rare liver disease like Wilson's disease.

Activities of asymmetric dimethylarginine-related enzymes in white adipose tissue are associated with circulating lipid biomarkers.

BACKGROUND: Asymmetric NG,NG-dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, is regulated by the enzymatic participants of synthetic and metabolic processes, i.e., type I protein N-arginine methyltransferase (PRMT) and dimethylarginine dimethylaminohydrolase (DDAH). Previous reports have demonstrated that circulating ADMA levels can vary in patients with type 1 and type 2 diabetes mellitus (T2DM). White adipose tissue expresses the full enzymatic machinery necessary for ADMA production and metabolism; however, modulation of the activities of adipose ADMA-related enzymes in T2DM remains to be determined. METHODS: A rodent model of T2DM using 11- and 20-week old Goto-Kakizaki (GK) rats was used. The expression and catalytic activity of PRMT1 and DDAH1 and 2 in the white adipose tissues (periepididymal, visceral and subcutaneous fats) and femur skeletal muscle tissue were determined by immunoblotting, in vitro methyltransferase and in vitro citrulline assays. RESULTS: Non-obese diabetic GK rats showed low expression and activity of adipose PRMT1 compared to age-matched Wistar controls. Adipose tissues from the periepididymal, visceral and subcutaneous fats of GK rats had high DDAH1 expression and total DDAH activity, whereas the DDAH2 expression was lowered below the control value. This dynamic of ADMA-related enzymes in white adipose tissues was distinct from that of skeletal muscle tissue. GK rats had lower levels of serum non-esterified fatty acids (NEFA) and triglycerides (TG) than the control rats. In all subjects the adipose PRMT1 and DDAH activities were statistically correlated with the levels of serum NEFA and TG. CONCLUSION: Activities of PRMT1 and DDAH in white adipose tissues were altered in diabetic GK rats in an organ-specific manner, which was reflected in the serum levels of NEFA and TG. Changes in adipose ADMA-related enzymes might play a part in the function of white adipose tissue.

Disruption of protein arginine N-methyltransferase 2 regulates leptin signaling and produces leanness in vivo through loss of STAT3 methylation.

RATIONALE: Arginine methylation by protein N-arginine methyltransferases (PRMTs) is an important posttranslational modification in the regulation of protein signaling. PRMT2 contains a highly conserved catalytic Ado-Met binding domain, but the enzymatic function of PRMT2 with respect to methylation is unknown. The JAK-STAT pathway is proposed to be regulated through direct arginine methylation of STAT transcription factors, and STAT3 signaling is known to be required for leptin regulation of energy balance. OBJECTIVE: To identify the potential role of STAT3 arginine methylation by PRMT2 in the regulation of leptin signaling and energy homeostasis. METHODS AND RESULTS: We identified that PRMT2(-/-) mice are hypophagic, lean, and have significantly reduced serum leptin levels. This lean phenotype is accompanied by resistance to food-dependent obesity and an increased sensitivity to exogenous leptin administration. PRMT2 colocalizes with STAT3 in hypothalamic nuclei, where it binds and methylates STAT3 through its Ado-Met binding domain. In vitro studies further clarified that the Ado-Met binding domain of PRMT2 induces STAT3 methylation at the Arg31 residue. Absence of PRMT2 results in decreased methylation and prolonged tyrosine phosphorylation of hypothalamic STAT3, which was associated with increased expression of hypothalamic proopiomelanocortin following leptin stimulation. CONCLUSIONS: These data elucidate a molecular pathway that directly links arginine methylation of STAT3 by PRMT2 to the regulation of leptin signaling, suggesting a potential role for PRMT2 antagonism in the treatment of obesity and obesity-related syndromes.

Impaired PRMT1 activity in the liver and pancreas of type 2 diabetic Goto-Kakizaki rats.

AIMS: Arginine methylation catalyzed by protein N-arginine methyltransferase (PRMT) 1 is implicated in a variety of cellular processes, although the potential role of PRMT1-mediated methylation in glucose intolerance has not been defined. This study aims to investigate whether alteration of PRMT1 activity contributes to the clinical features of type 2 diabetes. MAIN METHODS: Goto-Kakizaki (GK) rats were used as a rodent model of type 2 diabetes. Catalytic activity of PRMT1 and arginine methylation were determined by an in vitro methyltransferase assay and immunoblotting, respectively. Hepatic insulin signaling events, insulin secretion, and pancreatic glucose metabolism were assessed by studies using HepG2 hepatoma cells and isolated pancreatic islets. Methyltransferase activity was attenuated by transfection of a small interfering RNA against PRMT1 (PRMT1-siRNA) or by pretreatment with an inhibitor of methyltransferase, 5'-deoxy-5'-(methylthio)adenosine (MTA). KEY FINDINGS: Non-obese, diabetic GK rats exhibited a decrease in their hepatic and pancreatic PRMT1 activity, as compared to the control Wistar rats, which was associated with the impaired arginine methylation of several proteins in the tissues. Transfection of PRMT1-siRNA diminished the agonist-induced activation of insulin signaling and the subsequent suppression of gluconeogenic genes expression in the liver-derived cells. Pretreatment with MTA attenuated the glucose-stimulated insulin secretion, but not glucose utilization, in isolated pancreatic islets of Wistar controls, and its pattern was comparable to that of the GK rats undergoing similar modulation. SIGNIFICANCE: The present data demonstrates that the impaired PRMT1 activity may be implicated in glucose intolerance in GK rats through the disturbed hepatic glucose metabolism and insulin secretion.

Involvement of PRMT1 in hnRNPQ activation and internalization of insulin receptor.

Insulin signaling in skeletal L6 myotubes is known to be affected by arginine methylation catalyzed by protein N-arginine methyltransferase 1 (PRMT1), however, the mechanism by which this occurs has not yet been defined. This study aimed to determine the exact substrate involved in the methylation and regulating insulin signaling in cells. Insulin enhanced arginine methylation of a 66-kDa protein (p66) concomitant with translocation of PRMT1 to the membrane fraction. Peptide mass fingerprinting identified p66 as a heterogeneous nuclear ribonucleoprotein, hnRNPQ that was bound to and methylated by PRMT1. Pharmacological inhibition of methylation (MTA) and small interfering RNA against PRMT1 (PRMT1-siRNA) attenuated insulin-stimulated tyrosine phosphorylation of hnRNPQ and insulin receptor (IR), and the interaction between hnRNPQ and IR. MTA, PRMT1-siRNA, and hnRNPQ-siRNA inhibited internalization of IR in the same manner. These data suggest that the PRMT1-mediated methylation of hnRNPQ is implicated in IR trafficking and insulin signaling in skeletal L6 myotubes.

Protein arginine methylation regulates insulin signaling in L6 skeletal muscle cells.

Protein N-arginine methyltransferase (PRMT)1 catalyzes arginine methylation in a variety of substrates, although the potential role of PRMT1 in insulin action has not been defined. We therefore investigated the effect of PRMT1-mediated methylation on insulin signaling and glucose uptake in skeletal L6 myotubes. Exposure of L6 myotubes to insulin rapidly induced translocation of PRMT1 and increased its catalytic activity in membrane fraction. Several proteins in the membrane fraction were arginine-methylated after insulin treatment, which were inhibited by pretreatment with an inhibitor of methyltransferase, 5'-deoxy-5'-(methylthio)adenosine (MTA), or a small interfering RNA against PRMT1 (PRMT1-siRNA). Inhibition of arginine methylation with MTA or PRMT1-siRNA diminished later phase of insulin-stimulated tyrosine phosphorylation of insulin receptor (IR) beta and IRS-1, association of IRS-1 with p85alpha subunit of PI3-K, and glucose uptake. Our results suggest that PRMT1-mediated methylation serves as a positive modulator of IR/IRS-1/PI3-K pathway and subsequent glucose uptake in skeletal muscle cells.

Activation of cell adhesion kinase beta by mechanical stretch in vascular smooth muscle cells.

We have studied whether activation of cell adhesion kinase beta (CAKbeta) is involved in stretch-induced signaling pathway in cultured rat vascular smooth muscle cells. Cyclic stretch (1 Hz) induced a rapid (within 1 min) phosphorylation of CAKbeta, whose effect was time and strength dependent. Both Ca(2+) and Na(+) ionophores (A23187 and monensin) stimulated phosphorylation of CAKbeta in a similar fashion to mechanical stretch. The stretch-induced phosphorylation of CAKbeta was inhibited completely by an intracellular Ca(2+) chelator [1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester)] and largely by gadolinium, but only partially by an extracellular Ca(2+) chelator (EGTA). An angiotensin type 1 receptor antagonist (CV11974) abolished the phosphorylation of CAKbeta stimulated by angiotensin II, but not by mechanical stretch. Mechanical stretch rapidly (within 1 min) increased the association of CAKbeta with c-Src, but not pp125(focal adhesion kinase). Stretch-induced phosphorylation of ERK1/2 was inhibited by EGTA and an inhibitor of the Src kinase family [4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine], but not by cytochalasin D, to disrupt actin polymerization. 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine or cytochalasin D did not affect stretch-induced phosphorylation of CAKbeta. These data suggest that mechanical stretch stimulates activation of CAKbeta, followed by its association with c-Src, which requires ion influx mainly via stretch-activated nonselective ion channels, thereby leading to activation of the p21(Ras)/ERK1/2 cascade in vascular smooth muscle cells.

Adrenomedullin is an autocrine/paracrine growth factor for rat vascular smooth muscle cells.

Adrenomedullin is a potent vasodilator peptide secreted by vascular endothelial and smooth muscle cells. Adrenomedullin stimulates the proliferation of quiescent rat vascular smooth muscle cells (VSMCs) via p42/p44 ERK/MAP kinase activation. Recently, receptor-activity-modifying proteins (RAMPs) have been shown to transport calcitonin-receptor-like-receptor (CRLR) to the cell surface to present either as CGRP receptor or adrenomedullin receptor. We investigated whether adrenomedullin acts as an autocrine/paracrine growth factor for cultured rat VSMCs and whether coexpressions of RAMP isoform and CRLR may mediate p42/p44 ERK/MAP kinase activation by adrenomedullin. Adrenomedullin dose-dependently stimulated the proliferation of quiescent rat VSMCs, and this effect was inhibited by an adrenomedullin receptor antagonist, a MAP kinase kinase inhibitor and phosphatidylinositol 3-kinase inhibitors. Addition of either CGRP(8-37) or anti-adrenomedullin antibody to exponentially growing rat VSMCs inhibited the serum-induced cell proliferation, suggesting its role as an autocrine/paracrine growth factor. Cotransfection of RAMP2 or RAMP3 with CRLR into rat VSMCs potentiated activation of cAMP activity, but not of p42/p44 ERK/MAP kinase activity in response to adrenomedullin. Our results suggest that adrenomedullin is an autocrine/paracrine growth factor for rat VSMCs via p42/p44 ERK/MAP kinase and phosphatidylinositol 3-kinase pathways and that it is not mediated by human RAMP-CRLR receptors.