BCR/ABL oncogenic tyrosine kinase activates STAT5, which plays as important role in leukemogenesis (Nieborowska-Skorska et al., J.Exp.Med., 189:1229,1999). We reported before that the bcl-2 family ...member A1 and the proto-oncogene pim-1, the two downstream effectors of STAT5, collaborate in BCR/ABL-positive cells to induce protection from apoptosis and growth factor independence (Nieborowska-Skorska et al., Blood, 99:4531,2002). We show here that expression of the helix-loop-helix protein Id1 is enhanced by BCR/ABL in the STAT5-dependent manner. This effect requires activation of STAT5 by the signaling from SH3+SH2 domains of BCR/ABL. Enhanced expression of Id1 played a key role in the BCR/ABL-mediated cell invasion in vitro, but not in protection from apoptosis in the absence of growth factors and in promotion of growth factor-independent proliferation. Leukemogenesis in mice was prolonged after injection of BCR/ABL-positive cells, in which Id-1 was downregulated by the antisence cDNA. In addition, infiltration of central nervous system (CNS) by leukemia cells was also reduced if Id-1 was inhibited. Id1 was responsible for BCR/ABL-induced production of MMP9 metalloproteinase. Abrogation of MMP9 catalytic activity by a selective inhibitor or blocking antibody decreased the invasive capability of leukemia cells. These data indicate that BCR/ABL→STAT5→Id1→MMP9 pathway may play a critical role in the BCR/ABL-dependent leukemogenesis by regulation of the invasive capability of leukemia cells. Moreover, this pathway may protect CML cells from imatinib mesylate (IM) by facilitation of their localization in CNS, a sanctuary for leukemia cells during IM therapy.
Activating mutations in the KCNJ11 gene encoding the Kir6.2 subunit of ATP-sensitive potassium channel have been described in patients with permanent neonatal diabetes mellitus (PNDM). The main ...pathophysiological feature of PNDM associated with Kir6.2 mutations is a profound defect in insulin secretion. However, the expression of Kir6.2 protein is not limited to beta-cells; it also includes skeletal muscles, heart, brain, and peripheral nerves. Thus, the hypothesis that Kir6.2 mutations may influence insulin sensitivity in humans seems justified. Moreover, this notion is additionally supported by an animal model of Kir6.2 knock-out mice. Four adult carriers of a Kir6.2 mutation from the Polish population (mean age 31.5 years, range 20-50) were available for this study that aimed to evaluate their insulin sensitivity by the hyperinsulinemic euglycemic clamp technique. Three subjects carried the R201H mutation and one patient was a carrier of the K170N mutation. In addition, eight healthy volunteers with normal glucose tolerance were examined for comparison (mean age 31.0 years, range 20-41). The mean M value, i.e. the amount of metabolized glucose, for PNDM cases equaled 4.49 mg/(kg x min) (range 2.76-6.66) and was significantly lower than in the control group (9.64 mg/(kg x min), range 4.59-18.00). This observation suggests that impaired insulin sensitivity, in addition to profoundly decreased insulin secretion, contributes to the clinical picture of PNDM resulting from mutations in the Kir6.2 gene. An additional factor that might influence insulin sensitivity in our diabetes patients is glucose toxicity that may have appeared due to poor metabolic control prior to the examination (mean HbA1c = 8.95%). The intriguing question to be answered in the future is whether an improvement in insulin action could be seen following the transfer of Kir6.2 mutation carriers to sulphonylurea compounds.
BACKGROUND: Genetic variants of vitamin D-binding protein (DBP) have been reported to be associated, not only with diabetes, but also with prediabetic traits, in several populations. There are two ...known polymorphisms in exon 11 of the DBP gene that result in amino acid variants: at codons 416 GAT-->GAG (Asp-->Glu) and 420 ACG-->AAG (Thr-->Lys). OBJECTIVE: To examine the association of these polymorphisms with diabetes in white Americans of European origin. METHODS: We studied unrelated individuals: 181 with type 1 diabetes, 215 with type 2 diabetes, and 163 healthy controls. Exon 11 was amplified using polymerase chain reaction and the two alleles were determined by digestion with specific endonucleases: HaeIII and StyI, respectively. RESULTS: At codon 416, Asp/Glu allele frequencies were 45%/55% in patients with type 1 diabetes, 43%/57% in patients with type 2 diabetes, and 46%/54% in controls (chi(2)=0.69, 2 d.f., P<0.71). At codon 420, corresponding Lys/Thr frequencies were 27%/73%, 30%/70%, and 30%/70% (chi(2)=1.25, 2 d.f., P=0.53). Distributions of genotypes at both loci, and the haplotypes defined by the two loci, were also very similar in all groups. CONCLUSION: DNA polymorphisms in the DBP gene are not associated with diabetes in white Americans of European origin.
Genetics and environmental factors play a role in the pathogenesis of the complex disease, type 2 diabetes mellitus. Two major pathophysiological defects coexist in this disease: impairment of ...insulin secretion by beta-cells and decreased insulin sensitivity in peripheral tissues. The aim of the study was to examine whether two polymorphisms: the -308 G/A substitution in the promoter region of TNF-alpha gene and the K121Q amino acid variant of the PC-1 gene; influence insulin resistance in individuals with positive family history of type 2 diabetes mellitus.
Sixty individuals were included into this study: 28 women and 32 men, all of them with normal glucose tolerance. Insulin and glucose serum levels were were assessed during the OGTT on fasting and at 30 and 120 minutes. Secondary indices of insulin resistance were calculated based on these measurements. Genotyping of the both examined polymorphisms was performed using the restriction fragment length polymorphism method (RFLP).
Homozygous and heterozygous carriers of the A allele in position -308 of the TNF-alpha gene promoter showed higher plasma insulin levels at 120 min OGTT versus GG carriers (44.77 microliters/ml; SD 40.4 vs. 26.82; SD 19.9; p = 0.04) and a higher ratio of the 30 min increment in insulin to the 30 min increment in glucose (35.4; SD 21.5 vs. 22.6: SD 21.5; p = 0.03). In addition, homo- and heterozygous carriers of the Q allele at residue 121 of the PC-1 gene showed higher plasma glucose levels at 120 min OGTT compared to the KK subjects (5.38 mmol/l, SD 1.19 vs. 4.48, SD 1.11; p = 0.03).
Our study suggests that both examined polymorphisms: the -308 G/A in the promoter region of TNF-alpha and K121Q amino acid variant of the PC-1; influence the development of insulin resistance as a prediabetic quantitative trait in a Polish population.
Determinants of the Development of Diabetes (Maturity-Onset Diabetes of the Young-3) in Carriers of HNF-1 α Mutations
Evidence for parent-of-origin effect
Tomasz Klupa , MD 1 2 3 ,
James H. Warram , ...MD, SCD 1 ,
Anthony Antonellis , BS 1 ,
Marcus Pezzolesi , BS 1 ,
Moonsuk Nam , MD 1 2 ,
Maciej T. Malecki , MD, PHD 1 2 3 ,
Alessandro Doria , MD, PHD 1 2 ,
Stephen S. Rich , PHD 4 and
Andrzej S. Krolewski , MD, PHD 1 2
1 Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
2 Department of Medicine, Harvard Medical School, Boston, Massachusetts
3 Department of Metabolic Diseases, Medical College, Jagiellonian University, Krakow, Poland
4 Wake Forest University School of Medicine, Winston-Salem, North Carolina
Abstract
OBJECTIVE —To determine the distribution of the age at onset of diabetes (maturity-onset diabetes of the young-3 MODY3) and to identify
determinants of the onset of diabetes in carriers of HNF-1α mutations.
RESEARCH DESIGN AND METHODS —Extended families ( n = 104) with type 2 diabetes inherited in a dominant pattern were recruited and screened for diabetes-causing mutations in
HNF-1α .
RESULTS — HNF-1α mutations cosegregated with diabetes in only 13 families, all with a mean age at onset <35 years. Insulin secretion was diminished
or absent in mutation carriers ( n = 101), and diabetes developed in 65% by age 25 years and in 100% by age 50 years. If the mutation was inherited from the
mother, diabetes onset was very young in those exposed to diabetes in utero; 57 ± 8% were affected by age 15 years as compared
with 0.0% in those not exposed ( P < 7 × 10 −6 ). By age 25 years, the difference was reduced (85 ± 6 and 55 ± 12%, respectively; P = 0.02). If the mutation was inherited from the father, diabetes developed in 52 ± 8% by age 25 years. Age at diagnosis was
shown to be highly heritable ( h 2 = 0.47, P = 0.003). When parent of origin was included in the analyses, the magnitude of genetic contribution increased markedly ( h 2 = 0.91).
CONCLUSIONS —Mutations in HNF-1α accounts for diabetes in a small proportion of families with a dominant pattern of inheritance. Age at onset of diabetes
in MODY3 families varied widely and was influenced by familial factors (including modifying genes) and parent of origin (whether
a mutation carrier was exposed to diabetes in utero).
HNF-1α, hepatocyte nuclear factor 1α
IA2, insulinoma-associated antigen 2
MODY, maturity-onset diabetes of the young
OGTT, oral glucose tolerance test
WHO, World Health Organization
Footnotes
Address correspondence and reprint requests to Andrzej S. Krolewski, Section on Genetics & Epidemiology, Joslin Diabetes Center,
One Joslin Place, Boston, MA 02215. E-mail: andrzej.krolewski{at}joslin.harvard.edu .
Received for publication 8 May 2002 and accepted in revised form 3 August 2002.
A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
DIABETES CARE
Maternally inherited diabetes with deafness (MIDD) is a rare, monogenic form of diabetes mellitus caused by mutations in the mitochondrial genome, the most frequent being the A3243G substitution of ...the tRNA(Leu) gene. We screened 520 individuals with type 2 diabetes mellitus and 45 probands from families with a clinical picture of maturity onset diabetes of the young (MODY) using restriction fragment length polymorphism. One carrier of the mutation being investigated was found in a proband from a MODY family. The patient was a 20 year-old woman, diagnosed at the age of 16 years as having type 1 diabetes mellitus. On entry to the study, she was treated by a multiple daily injection regimen (MDI) with regular human insulin and human NPH insulin. Typical extra-pancreatic symptoms of MIDD were present, such as macular pattern dystrophy and mild bilateral sensory hearing loss. Additionally, the patient presented abdominal obesity (BMI 32.0), an uncommon feature in monogenic insulin secretion defects, including MIDD. To facilitate weight loss, the diabetes treatment was modified. Since metformin treatment is considered to be contraindicated in MIDD because of the increased risk of lactic acidosis, we used insulin analogues (aspart and detemir) in an MDI regimen and hypocaloric diet. This resulted in a 6.3 kg weight reduction (BMI 27.4) and normalization of HbA1c level (from 7.2 to 6.1 %) during a three-month follow-up. On the basis of this case, we suggest that an MDI regimen with insulin analogues may be a preferred therapeutic option in some rare clinical situations, such as MIDD associated with obesity.
We studied the effect of the modification of focal adhesion kinase (FAK) on the growth, migration and adhesion of C3H 10T1/2 cells. Cells transfected with plasmid coding for antisense FAK displayed a ...low level of FAK protein. Interestingly, the transfected cells achieved a higher saturation density at confluence, and displayed reduced adhesion and enhanced emigration from a confluent layer of cells when stimulated with fibronectin. In conclusion, it can be postulated that FAK plays an important role in the mechanism of contact inhibition.
It has recently been shown that polymorphisms of some genes might influence the genetic susceptibility to complex, multifactorial forms of type 2 diabetes mellitus (T2DM). One of those genes is ...peroxisome proliferator activated receptor gamma (PPARgamma). The PPARgamma gene product is a nuclear hormone receptor that regulates adipogenesis and is a target for thiazolidinediones, medications enhancing sensitivity to insulin. The Pro12Ala amino acid variant of the PPARgamma2 isoform is associated with T2DM in several populations.
(1) To determine the allele and genotype frequency of the Pro12Ala PPARgamma2 amino acid variant in a Polish population; (2) To search for the association of the Pro12Ala polymorphism with T2DM in the examined population.
We included 644 individuals in this study: 366 T2DM patients with age of diagnosis greater than 35 years and 278 non-diabetic control subjects. The fragment of the PPARgamma2 gene which contains the examined amino acid variant was amplified by polymerase chain reaction (PCR). Alleles and genotypes were determined based on electrophoresis of the DNA digestion products by the specific restriction enzyme BshI. Differences in distribution between the groups were examined by chi2 test.
The frequency of Pro/Ala alleles was similar in T2DM patients and in the control subjects (83.5%/16.5% vs. 84.5%/15.5%, respectively, P=0.607). Similarly, there was no difference between the groups when we analysed the genotype distribution. Stratification analyses based on age of diagnosis, body mass index (BMI), and family history of T2DM were performed. The Pro/Ala and Ala/Ala genotypes tended to be more frequent in T2DM cases with age of diagnosis >50 years than in controls (36.2% vs. 27.3%, P=0.046). This difference was not significant after Sheffe correction for multiple comparisons. The other stratification analyses did not show any difference between the groups.
The frequency of the Pro12Ala PPARgamma2 polymorphism in the Polish population studied is similar to that in other Caucasian populations. In the case-control study, we were not able to confirm earlier reports that the Pro allele conferred an increased risk for development of T2DM. Moreover, the results of the stratified analysis suggest an opposite trend in late onset T2DM.
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