Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nuclear hormone receptor PPAR gamma promotes adipogenesis and macrophage differentiation and is a primary pharmacological target in the treatment of type II diabetes. Here, we show that PPAR gamma gene knockout results in two independent lethal phases. Initially, PPAR gamma deficiency interferes with terminal differentiation of the trophoblast and placental vascularization, leading to severe myocardial thinning and death by E10.0. Supplementing PPAR gamma null embryos with wild-type placentas via aggregation with tetraploid embryos corrects the cardiac defect, implicating a previously unrecognized dependence of the developing heart on a functional placenta. A tetraploid-rescued mutant surviving to term exhibited another lethal combination of pathologies, including lipodystrophy and multiple hemorrhages. These findings both confirm and expand the current known spectrum of physiological functions regulated by PPAR gamma.
Mol Cell 1999 Oct
PMID:PPAR gamma is required for placental, cardiac, and adipose tissue development. 1054 90

Patients with Dunnigan-type familial partial lipodystrophy (FPLD) are born with normal fat distribution, but after puberty experience regional and progressive adipocyte degeneration, often associated with profound insulin resistance and diabetes. Recently, the FPLD gene was mapped to chromosome 1q21-22, which harbours the LMNA gene encoding nuclear lamins A and C. Mutations in LMNA were shown to underlie autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD-AD), which is characterized by regional and progressive skeletal muscle wasting and cardiac effects. We hypothesized that the analogy between the regional muscle wasting in EDMD-AD and the regional adipocyte degeneration in FPLD, in addition to its chromosomal localization, made LMNA a good candidate gene for FPLD. DNA sequencing of LMNA in five Canadian FPLD probands indicated that each had a novel missense mutation, R482Q, which co-segregated with the FPLD phenotype and was absent from 2000 normal alleles ( P = 1.1 x 10(-13)). This is the first report of a mutation underlying a degenerative disorder of adipose tissue and suggests that LMNA mutations could underlie other diseases characterized by tissue type- and anatomical site-specific cellular degeneration.
Hum Mol Genet 2000 Jan 01
PMID:Nuclear lamin A/C R482Q mutation in canadian kindreds with Dunnigan-type familial partial lipodystrophy. 1058 85

In mice with too little fat (lipodystrophy) or too much fat (ob/ob), leptin deficiency leads to hyperglycemia, hyperinsulinemia, and insulin resistance. In both disorders, the liver overproduces glucose as a result of resistance to the normal action of insulin in repressing mRNAs for gluconeogenic enzymes. Here we show that chronic hyperinsulinemia downregulates the mRNA for IRS-2, an essential component of the insulin-signaling pathway in liver, thereby producing insulin resistance. Despite IRS-2 deficiency, insulin continues to stimulate production of SREBP-1c, a transcription factor that activates fatty acid synthesis. The combination of insulin resistance (inappropriate gluconeogenesis) and insulin sensitivity (elevated lipogenesis) establishes a vicious cycle that aggravates hyperinsulinemia and insulin resistance in lipodystrophic and ob/ob mice.
Mol Cell 2000 Jul
PMID:Decreased IRS-2 and increased SREBP-1c lead to mixed insulin resistance and sensitivity in livers of lipodystrophic and ob/ob mice. 1094 29

Dunnigan-type familial partial lipodystrophy (FPLD; OMIM 151660) is a rare monogenic form of insulin resistance characterized by loss of subcutaneous fat from the extremities, trunk, and gluteal region. FPLD recapitulates the main metabolic attributes of the insulin resistance syndrome, including central obesity, hyperinsulinemia, glucose intolerance and diabetes, dyslipidemia, and hypertension. Through the use of focused DNA sequencing of positional candidate genes on chromosome 1q21, we discovered that FPLD results from mutations in LMNA (R482Q; OMIM 150330.0010), which is the gene that encodes nuclear lamins A and C. By stratifying members of extended FPLD pedigrees according to LMNA genotype, we found that hyperinsulinemia is present early in the course of the disease and that dyslipidemia (characterized by high triglycerides and depressed HDL cholesterol) precedes the development of glucose abnormalities. Plasma leptin is also markedly reduced in subjects with FPLD due to mutant LMNA. The findings in FPLD indicate that defective structure of the nuclear envelope produces a phenotype of insulin resistance. The findings may have relevance for common insulin resistance and for drug-associated lipodystrophies, whose molecular basis is unknown at present.
Mol Genet Metab 2000 Dec
PMID:Familial partial lipodystrophy: a monogenic form of the insulin resistance syndrome. 1113 44

Large subcutaneous abdominal adipocyte size (s.c. abd. AS) is associated with insulin resistance and predicts type 2 diabetes in Pima Indians. Because type 2 diabetes is familial, we aimed to determine whether mean s.c. abd. AS is also familial and if so, to identify chromosomal regions linked to this measure. Body composition (hydrodensitometry) and mean s.c. abd. AS (fat biopsy) were measured in 295 Pima Indians (179 with normal, 80 with impaired, and 36 with diabetic glucose tolerance) representing 164 nuclear families. Mean s.c. abd. AS, adjusted for age, sex, and percentage body fat was a familial trait (heritability h(2) = 0.48, P < 0.0001). A genome-wide autosomal scan revealed suggestive evidence for linkage (LOD 1.73) of adjusted mean s.c. abd. AS to chromosome 1q21--q23, a region containing LMNA, the gene encoding for the nuclear envelope proteins lamin A/C. Rare mutations in LMNA were recently shown to underlie familial partial lipodystrophy (FPLD), a syndrome characterized by regional loss of adipose tissue, insulin resistance, and glucose intolerance. A common (allelic frequency 0.43) single nucleotide polymorphism (silent 1908C --> T substitution) in exon 10 of LMNA (GenBank X03444) was associated with reduced age-, sex- and percentage body fat-adjusted mean s.c. abd. AS [0.80 +/- 0.17 (CC), 0.76 +/- 0.15 (CT), 0.73 +/- 0.16 (TT) microg lipid/cell, P < 0.05 for CC vs TT]. These findings indicate that approximately half of the variance in mean s.c. abd. AS can be attributed to familial factors and that genetic variation in LMNA might not only underlie rare cases of FPLD, but may also contribute to variation in adipocyte size in the general population.
Mol Genet Metab 2001 Mar
PMID:Subcutaneous abdominal adipocyte size, a predictor of type 2 diabetes, is linked to chromosome 1q21--q23 and is associated with a common polymorphism in LMNA in Pima Indians. 1124 29

Lipodystrophy is characterized by altered partition of adipose tissue. Despite heterogeneous causes, which include genetic, autoimmune and drug-induced forms, lipodystrophy syndromes have similar metabolic attributes, including insulin resistance, hyperlipidemia and diabetes. The mechanisms underlying the insulin resistance are unknown. One form of lipodystrophy, namely Dunnigan-type familial partial lipodystrophy (FPLD) was shown to result from mutations in the LMNA gene, which encodes nuclear lamins A and C. Although the relationship between the mutations in the nuclear envelope and insulin resistance is unclear at present, these findings might eventually be shown to have relevance for the common insulin resistance syndrome and for drug-associated lipodystrophies.
Trends Mol Med 2001 Mar
PMID:Molecular basis of partial lipodystrophy and prospects for therapy. 1128 83

Deficiency of leptin or its receptor produces hyperinsulinemia with marked obesity. Paradoxically, severe insulin resistance also accompanies lipodystrophy. Animal models of these contrasting conditions have enabled us to observe the profound and complicated aspects of the underlying pathologies. In addition, conventional polygenic rodents with known genetic backgrounds, such as the spontaneously hypertensive rat and the Goto-Kakisaki rat, have also been used to investigate these abnormalities.
Trends Mol Med 2001 Aug
PMID:Disease model: hyperinsulinemia and insulin resistance. Part B--polygenic and other animal models. 1151 99

The X-linked form of Emery-Dreifuss muscular dystrophy (X-EDMD) is caused by absence, or greatly reduced amounts, of the inner nuclear-membrane protein, emerin. The autosomal dominant form (AD-EDMD) is caused by missense mutations in lamins A and C, two components of the nuclear lamina that interact directly with emerin. Lamin A/C mutations also cause one form of dilated cardiomyopathy (CMD1A) and one form of limb-girdle muscular dystrophy (LGMD1B), both of which have clinical features in common with EDMD, as well as a rare, unrelated form of lipodystrophy (FPLD). Evidence is now emerging that defective assembly of the nuclear lamina is a feature of all these diseases, although not necessarily the direct cause. Why only heart and skeletal muscle, and possibly connective tissue, are affected in EDMD and why expression of the disease is so extremely variable between individuals remains to be explained.
Trends Mol Med 2001 Dec
PMID:The role of the nuclear envelope in Emery-Dreifuss muscular dystrophy. 1173 21

We summarize the properties of integral membrane proteins that reside in the inner nuclear membrane, including lamin B receptor (LBR), lamina-associated polypeptide (LAP) 1, LAP2, emerin, MAN1 and nurim. Most of these proteins interact with lamins and chromatin. Some data also suggest more speculative functions such as gene regulation and possibly sterol metabolism. Mutations in emerin and nuclear lamins have been associated with muscular dystrophies and lipodystrophy, raising new questions about the functions of inner nuclear membrane proteins. Integral proteins of the inner nuclear membrane are synthesized on the rough endoplasmic reticulum (ER) and reach the inner nuclear membrane by lateral diffusion in the connected ER and nuclear envelope membranes. Associations with nuclear ligands retain them in the inner nuclear membrane. Further investigation of the functions and targeting of inner nuclear membrane proteins are needed to determine how they are involved in human disease.
Cell Mol Life Sci 2001 Nov
PMID:Inner nuclear membrane proteins: functions and targeting. 1176 74

The gene encoding nuclear lamins A and C is mutated in at least three inherited disorders. Two of these, Emery-Dreifuss muscular dystrophy (EDMD-AD) and a form of dilated cardiomyopathy (CMD1A), involve muscle defects, and the other, familial partial lipodystrophy (FPLD), involves loss of subcutaneous adipose tissue. Mutations causing FPLD, in contrast to those causing muscle disorders, are tightly clustered within the C-terminal domain of lamin A/C. We investigated the expression and subcellular localization of FPLD lamin A mutants and found no abnormalities. We therefore set out to identify proteins interacting with the C-terminal domain of lamin A by screening a mouse 3T3-L1 adipocyte library in a yeast two-hybrid interaction screen. Using this approach, the adipocyte differentiation factor, sterol response element binding protein 1 (SREBP1) was identified as a novel lamin A interactor. In vitro glutathione S-transferase pull-down and in vivo co-immunoprecipitation studies confirmed an interaction between lamin A and both SREBP1a and 1c. A binding site for lamin A was identified in the N-terminal transcription factor domain of SREBP1, between residues 227 and 487. The binding of lamin A to SREBP1 was noticeably reduced by FPLD mutations. Interestingly, one EDMD-AD mutation also interfered with the interaction between lamin A and SREBP1. Whilst the physiological relevance of this interaction has yet to be elucidated, these data raise the intriguing possibility that fat loss seen in laminopathies may be caused, at least in part, by reduced binding of the adipocyte differentiation factor SREBP1 to lamin A.
Hum Mol Genet 2002 Apr 01
PMID:A novel interaction between lamin A and SREBP1: implications for partial lipodystrophy and other laminopathies. 1192 49


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