Biomedical subjects

Douglas A Marchuk

Publications and source records attributed to Douglas A Marchuk.

40 records · Page 3Linked to original sources

PubMed2002

Genetic modifier loci affecting survival and cardiac function in murine dilated cardiomyopathy.

BACKGROUND: Understanding the role for genetic factors in human heart failure is difficult because environmental factors cannot be standardized and genetic variation is great. One approach to identify genes that modify disease outcome is to use mouse models that show strong genetic variation of the disease phenotype. METHODS AND RESULTS: In this study, we used transgenic mice that develop severe dilated cardiomyopathy due to the cardiac-specific overexpression of calsequestrin. Transgenic mice showed marked strain-specific variation of cardiac function and survival, independent of transgene expression. A reciprocal backcross strategy was employed using two inbred strains showing distinct differences in survival and cardiac function. To map the genes that modified the heart failure phenotype, progeny from the 2 reciprocal backcrosses were used in a genome-wide scan for linkage. We identified two loci significantly linked to survival with a maximum likelihood ratio statistic of 36.2 (LOD score approximately 7.8) on chromosome 2 and of 26.5 (LOD score approximately 5.7) on chromosome 3. The chromosome 3 locus was also significantly linked to cardiac function with a maximum likelihood ratio statistic of 42.9 (LOD score approximately 9.3). Because only a single strong modifier locus was found in each backcross, we applied a haplotype analysis to map crossovers and successfully narrowed the critical intervals for each locus. CONCLUSION: Using a sensitized mouse model, we identified major modifier loci that affect the genetically complex disease of heart failure. This approach should allow the rapid identification of candidate genes involved in disease susceptibility in human populations and new insights into the pathogenesis of heart failure.

Animals↗

PubMed2002

KRIT1 association with the integrin-binding protein ICAP-1: a new direction in the elucidation of cerebral cavernous malformations (CCM1) pathogenesis.

Mutations in KRIT1, a protein initially identified based on a yeast two-hybrid interaction with the RAS-family GTPase RAP1A, are responsible for the development of the inherited vascular disorder cerebral cavernous malformations (CCM1). As the function of the KRIT1 protein and its role in CCM pathogenesis remain unknown, we performed yeast two-hybrid screens to identify additional protein binding partners. A fragment containing the N-terminal 272 amino acid residues of KRIT1, a region lacking similarity to any known protein upon database searches, was used as bait. From parallel screens of human fetal brain and HeLa cDNA libraries, we obtained multiple independent isolates of human integrin cytoplasmic domain-associated protein-1 (ICAP-1) as interacting clones. The interaction of KRIT1 and ICAP-1 was confirmed by GST-KRIT1 trapping of endogenous ICAP-1 from 293T cells. The alpha isoform of ICAP-1 is a 200 amino acid serine/threonine-rich phosphoprotein which binds the cytoplasmic tail of beta1 integrins. We show that mutagenesis of the N-terminal KRIT1 NPXY amino acid sequence, a motif critical for ICAP-1 binding to beta1 integrin molecules, completely abrogates the KRIT1/ICAP-1 interaction. The interaction between ICAP-1 and KRIT1, and the presence of a FERM domain in the latter, suggest that KRIT1 might be involved in the bidirectional signaling between integrin molecules and the cytoskeleton. Furthermore, these data suggest that KRIT1 might affect cell adhesion processes via integrin signaling in CCM1 pathogenesis.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Somatic mutation of vascular endothelial growth factor receptors in juvenile hemangioma.

Juvenile hemangiomas are the most common tumors of infancy, occurring in as many as 10% of all births. These benign vascular lesions enlarge rapidly during the first year of life by hyperplasia of endothelial cells and attendant pericytes and then spontaneously involute over a period of years, leaving loose fibrofatty tissue. Several hypotheses have been put forth concerning hemangiogenesis, including the possibility that the tumor is the result of somatic mutation in one or more components of critical vascular growth-regulatory pathways. To test this hypothesis, we obtained 15 proliferative-phase hemangiomas after surgical resection and dissected them to enrich for the lesional (endothelial and pericytic) components of each specimen. To determine whether hemangiomas represent a clonal expansion from a single progenitor cell, we assayed X-inactivation patterns for each lesion by using the polymorphic X-linked human androgen receptor gene. Twelve of 14 informative hemangiomas showed a significant degree of allelic loss after methylation-based and transcription-based polymerase chain reaction clonality assays, suggesting a nonrandom X-inactivation pattern and, thus, a monoclonal origin. We then sequenced genes encoding the receptors of the vascular endothelial growth factors (VEGFs) as candidates for potential somatic mutation. Mutations were found in two of the 15 hemangioma specimens: a missense mutation (P1147S) in the kinase domain of the VEGFR2 (FLK1/KDR) gene in one specimen and a missense mutation (P954S) in the kinase insert of the VEGFR3 (FLT4) gene in another specimen. In each case, the mutation was detected in tumor tissue but not in adjacent normal tissue. These results suggest that one potential mechanism involved in hemangioma formation is the alteration of the VEGF signaling pathway in endothelial and/or pericytic cells.

Clone Cells↗

PubMedDate not supplied

Allelic differences in the serotonin transporter-linked polymorphic region in geriatric depression.

Previous studies have examined the role of genetic variations in the serotonin transporter-linked polymorphic region (5HTTLPR) in affective disorders. The authors studied 182 older depressed subjects and 107 elderly control subjects and obtained DNA for genotyping at the 5HTTLPR. There were no significant differences in allele frequencies generally or for number of short alleles for the group as a whole, but interesting gender effects emerged. Among men, 23% of depressed men had two short alleles, compared with only 5% of control subjects. Among women, 67% of depressed women with more than one episode had at least one short allele, compared with 41% of single-episode female patients. Also, 74% of women with a positive family history of psychiatric illness in any female relative had at least one short allele, whereas 53% had at least one short allele who did not have such a family history. Our results add to the literature linking this gene to affective illness. The negative association of allele frequency and depression may be related to the relatively small sample size. The findings raise the possibility that this genetic locus may exert differential effects based on gender, increasing risk in men, and increasing risk of recurrence in women.

Aged↗