[Molecular mechanisms of the alternative lipogenic function of insulin].

The proposed hypothesis suggests that major function of insulin is stimulation of triglyceride accumulation in adipose tissue and glycogen synthesis in liver and muscles. The impairment of insulin functioning diminishes triglyceride storage in adipose tissue, elevates the level of its metabolite in periphery and suppresses glucose intake by cells. Leptin disturbs direct insulin action on adipocytes, and prevents fat accumulation. Leptin deficiency or impairment of its functioning facilitate lipogenic effect of insulin, and induce obesity. Lipodystrophy decreases leptin secretion and enhances triglyceride production activated by insulin. Triglycerides are not accumulated in adipose tissue because of its deficiency, and overwhelm peripheral tissues. Lipid metabolites decrease glucose consumption and induce lipoatrophic diabetes. The hypothesis on the lipogenic insulin functioning is confirmed by specific knockout of Insr gene in only tissue: muscles, adipose tissue and other, and by the restoration of its expression in transgenic mice.

Do you know this syndrome? Berardinelli-Seip syndrome.

Berardinelli-Seip syndrome is a rare autosomal recessive disease characterized by inadequate metabolism and inefficient storing of lipids in fat cells, generating accumulation of fat in organs such as the liver, spleen, pancreas, heart, arterial endothelium and skin. Classically, patients manifest generalized lipoatrophy at birth or until 2 years of age, and in adolescence usually develop marked insulin resistance with rapid progression to diabetes and dyslipidemia. We report the case of a 17-year-old Berardinelli-Seip syndrome patient with eruptive xanthoma associated with severe hypertriglyceridemia. It is worth noting Eruptive xanthoma as a dermatological manifestation that is not generally highlighted in the reports of cases of this genetic metabolic disorder.

Inhibition of the chemokine (C-C motif) ligand 2/chemokine (C-C motif) receptor 2 pathway attenuates hyperglycaemia and inflammation in a mouse model of hepatic steatosis and lipoatrophy.

AIMS/HYPOTHESIS: Using a mouse model of lipoatrophic diabetes, we hypothesised that the chemokine (C-C motif) ligand 2 (CCL2)/chemokine (C-C motif) receptor 2 (CCR2) pathway contributes to hepatic macrophage accumulation and insulin resistance through induction of a chronic inflammatory state. METHODS: Metabolic variables of insulin resistance and inflammation were characterised in wild-type and lipoatrophic A-ZIP/F-1 transgenic (AZIP-Tg) mice. The AZIP-Tg mice were then treated with a CCR2 antagonist (RS504393, 2 mg kg(-1) day(-1)) or vehicle for 28 days via a subcutaneous mini-osmotic pump to examine the role of the CCL2/CCR2 pathway in lipoatrophic diabetes. RESULTS: The lipoatrophic AZIP-Tg mice were diabetic with high fasting glucose and serum insulin concentrations compared with littermate controls. The livers of AZIP-Tg mice were more than threefold enlarged and exhibited increased triacylglycerol content. CCL2 levels were highly elevated in both liver and serum of the AZIP-Tg mice compared with controls. In addition, the circulating CCL2 concentration was associated with increased macrophage accumulation and inflammation as documented by upregulation of Cd68 gene and Tnf-alpha [also known as Tnf] gene in livers from the AZIP-Tg mice. Treatment of the lipoatrophic AZIP-Tg mice with the CCR2 antagonist ameliorated the hyperglycaemia, hyperinsulinaemia and hepatomegaly in conjunction with a reduction in liver inflammation. CONCLUSIONS/INTERPRETATION: These findings demonstrate a significant role of the CCL2/CCR2 pathway in lipoatrophy-induced diabetes and provide clear evidence that metabolic improvements resulting from the inhibition of this inflammatory pathway are not adipose tissue-dependent.

Adrenocortical changes and arterial hypertension in lipoatrophic A-ZIP/F-1 mice.

The A-ZIP/F-1 transgenic mouse is a model of lipoatrophic diabetes with severe insulin resistance, hyperglycemia and hyperlipidemia. Recently, a regulatory role of adipose tissue on adrenal gland function and blood pressure has been suggested. To further explore the importance of adipose tissue in the regulation of adrenal function and blood pressure, we studied this mouse model of lipodystrophy. A-ZIP/F-1 mice exhibit significantly elevated systolic and diastolic blood pressure values despite lack of white adipose tissue and its hormones. Furthermore, A-ZIP/F-1 lipoatrophic mice have a significant reduction of adrenal zona glomerulosa, while plasma aldosterone levels and aldosterone synthase mRNA expression remain unchanged. On the other hand, lipoatrophic mice present elevated corticosterone levels but no adrenocortical hyperplasia. Ultrastructural analysis of adrenal gland show significant alterations in adrenocortical cells, with conformational changes of mitochondrial internal membranes and high amounts of liposomes. In conclusion, lipodystrophy in A-ZIP/F-1 mice is associated with hypertension, possibly due to hypercorticosteronemia and/or others metabolic-vascular changes.

An imaging study of body composition including lipodeposition pattern in a patient of familial partial lipodystrophy (Dunnigan type).

Familial Partial Lipodystrophy, Dunnigan type (FPLD), is characterised by loss of subcutaneous fat from the limbs and an excessive accumulation of fat on the neck, shoulder girdle and face. Affected individuals have insulin resistance, dyslipidaemia and early cardiovascular events. Body composition (BC) with details of adipose tissue distribution were studied by Dual-Energy X-ray Absorptiometry (DEXA) and Magnetic Resonance Imaging (MRI) ina heterozygote for the FPLD mutation LMNA R482W, and in an age, sex and body mass index (BMI) matched normal control. DEXA revealed a marked decrease in total as well as regional fat percentage in the patient compared to a normal control. Marked reductions in subcutaneous fat in the extremities with substantial lipodeposition in the nape of the neck were confirmed with. MRI. The importance of increased perinephric, retroperitoneal and intermuscular fat in the thighs found in this patient, needs to be explored vis-à-vis the pathogenesis of insulin resistance found in FPLD.

Patients with familial partial lipodystrophy of the Dunnigan type due to a LMNA R482W mutation show muscular and cardiac abnormalities.

Diseases due to mutations in the lamin A/C gene (LMNA) are highly heterogeneous, including neuromuscular and cardiac dystrophies, lipodystrophies, and premature ageing syndromes. In this study we characterized the neuromuscular and cardiac phenotypes of patients bearing the heterozygous LMNA R482W mutation, which is the most frequent genotype associated with the familial partial lipodystrophy of the Dunnigan type (FPLD). Fourteen patients from two unrelated families, including 10 affected subjects, were studied. The two probands had been referred for lipoatrophy and/or diabetes. Lipodystrophy, exclusively observed in LMNA-mutated patients, was of variable severity and limited to postpubertal subjects. Lipodystrophy and metabolic disturbances were more severe in women, even if an enlarged neck was a constant finding. The severity of hypertriglyceridemia and hirsutism in females was related to that of insulin resistance. Clinical muscular alterations were only present in LMNA-mutated patients. Clinical and histological examination showed an invalidating, progressive limb-girdle muscular dystrophy in a 42-yr-old woman that had been present since childhood, associated with a typical postpubertal FPLD phenotype. Six of eight adults presented the association of calf hypertrophy, perihumeral muscular atrophy, and a rolling gait due to proximal lower limb weakness. Muscular histology was compatible with muscular dystrophy in one of them and/or showed a nonspecific excess of lipid droplets (in three cases). Immunostaining of lamin A/C was normal in the six muscular biopsies. Surprisingly, calpain 3 expression was undetectable in the patient with the severe limb-girdle muscular dystrophy, although the gene did not reveal any molecular alterations. At the cardiac level, cardiac septal hypertrophy and atherosclerosis were frequent in FPLD patients. In addition, a 24-yr-old FPLD patient had a symptomatic second degree atrioventricular block. In conclusion, we showed that most lipodystrophic patients affected by the FPLD-linked LMNA R482W mutation show muscular and cardiac abnormalities. The occurrence and severity of the myopathic and lipoatrophic phenotypes varied and were not related. The muscular phenotype was evocative of limb girdle muscular dystrophy. Cardiac hypertrophy and advanced atherosclerosis were frequent. FPLD patients should receive careful neuromuscular and cardiac examination whatever the underlying LMNA mutation.

[Partial lipodystrophy with C3 complement deficiency in 8 years old girl]. / Zespól lipodystrofii ograniczonej - czesciowej, z niedoborem skladowej c3 dopelniacza u 8-letniej dziewczynki.

Lipodystrophy is a rare, heterogenic disorder, leading to the loss of adipose tissue. Several main types of the disease are distinguished according to age of onset and localization of fat atrophy. The authors present the case of 8 years old girl with partial lipodystrophy, C3 complement deficiency and autoimmunologic disorder.

Diabetes-induced, progressive endometrial involution characterization of periluminal epithelial lipoatrophy.

The present studies detail the cytopathological alterations in uterine epithelial, basal lamina, and stromal endometrial subregions, and associated endocrine parameters that occur during the progressive exacerbation of the diabetes syndrome in this species of mouse. These alterations result in a cellular lipoatrophic condition that compromises uterine tissue integrity and promotes reproductive involution. Uterine tissue samples were obtained from litter-matched control (+/?) and diabetic (db/db) C57BL/KsJ mice at four designated stages of the progressive expression of the diabetes mutation. In db/db mice between the ages of 4 and 12 weeks, the uterine epithelial cellular architecture exhibited progressive deterioration, characterized by cytoplasmic lipid imbibition (accumulation), organelle disintegration, apical membrane ciliary regression, and peristromal lamina separation from basal membrane surfaces, as compared with control indexes. The cytoplasmic volume occupied by lipid inclusions dominated the epithelial cells in diabetic mice, presenting dense basal pole lipid vacuoles, with perinuclear-intracytoplasmic migration of the inclusions promoting an apical cytoplasmic lipid condensation of increasing volume 8-12 weeks after mutation expression. These cytoplasmic lipid accumulations occurred under altered metabolic and endocrine conditions characterized by hyperglycemic, hyperinsulinemic, hypertriglyceridemic, and enhanced noradrenergic indexes, which were exacerbated between 4- and 12-week stages. These structural changes were accompanied by enhanced adrenergic counterregulatory metabolic responses as well as elevated lipoprotein and triacylglycerol lipase activities. These data indicate that diabetes-associated uterine involution is characterized by a progressive cellular and peristromal lipoatrophy of epithelial cell cytology and metabolic parameters, promoting stromal separation and ultimate endometrial involution.

Lipoatrophic diabetes-associated utero-ovarian dysfunction: influence of cellular lipid deposition on norepinephrine indices.

OBJECTIVE: Elucidation of the intracellular lipoatrophic diabetic state and the concomitant alterations in norepinephrine (NE) parameters characterizing female reproductive failure. METHODS: Quantitation of intrinsic NE levels in utero-ovarian and pancreatic tissue samples of C57BL/KsJ (+/?) control and (db/db) diabetic littermate mice was by high performance liquid chromatography (HPLC) and compared with the microspectrofluorometric histofluorescent (HF) localization of cellular and parenchymal NE. RESULTS: Diabetes-associated elevations in HPLC-detectable tissue NE concentrations occurred in all pancreatic and reproductive tract tissue samples as compared to control-matched samples, whereas concurrent HF analysis revealed suppressed perivascular and parenchymal NE depositions in diabetic mice. CONCLUSIONS: These data suggest that progressive hypertriglyceridemia/lipidemia may suppress the effectiveness of intrinsic elevations in tissue NE concentrations from effectively counterregulating the deleterious effects of the hyperglycemic, type-2 diabetic condition.

Transgenic overexpression of leptin rescues insulin resistance and diabetes in a mouse model of lipoatrophic diabetes.

Lipoatrophic diabetes is caused by a deficiency of adipose tissue and is characterized by severe insulin resistance, hypoleptinemia, and hyperphagia. The A-ZIP/F-1 mouse (A-ZIPTg/+) is a model of severe lipoatrophic diabetes and is insulin resistant, hypoleptinemic, hyperphagic, and shows severe hepatic steatosis. We have also produced transgenic "skinny" mice that have hepatic overexpression of leptin (LepTg/+) and no adipocyte triglyceride stores, and are hypophagic and show increased insulin sensitivity. To explore the pathophysiological and therapeutic roles of leptin in lipoatrophic diabetes, we crossed LepTg/+ and A-ZIPTg/+ mice, producing doubly transgenic mice (LepTg/+:A-ZIPTg/+) virtually lacking adipose tissue but having greatly elevated leptin levels. The LepTg/+:A-ZIPTg/+ mice were hypophagic and showed improved hepatic steatosis. Glucose and insulin tolerance tests revealed increased insulin sensitivity, comparable to LepTg/+ mice. These effects were stable over at least 6 months of age. Pair-feeding the A-ZIPTg/+ mice to the amount of food consumed by LepTg/+:A-ZIPTg/+ mice did not improve their insulin resistance, diabetes, or hepatic steatosis, demonstrating that the beneficial effects of leptin were not due to the decreased food intake. Continuous leptin administration that elevates plasma leptin concentrations to those of LepTg/+:A-ZIPTg/+ mice also effectively improved hepatic steatosis and the disorder of glucose and lipid metabolism in A-ZIP/F-1 mice. These data demonstrate that leptin can improve the insulin resistance and diabetes of a mouse model of severe lipoatrophic diabetes, suggesting that leptin may be therapeutically useful in the long-term treatment of lipoatrophic diabetes.

Patients with lipodystrophic diabetes mellitus of the Seip-Berardinelli type, express normal insulin receptors.

Lipodystrophic diabetes mellitus of the Seip-Berardinelli type is a syndrome associated with insulin resistance and recessive inheritance. We have examined whether mutations in the insulin receptor are pathogenetic factors in this syndrome. Fibroblasts from three different patients with Seip-Berardinelli's lipodystrophy were tested for insulin binding, and insulin-stimulated receptor autophosphorylation. In addition, the coding region of both alleles of the iinsulin receptor gene was sequenced. No abnormalities in the number of high affinity insulin binding sites, and insulin-stimulated receptor autophosphorylation were detected. The insulin receptor related insulin-like growth factor I receptor also showed no functional changes. DNA sequence analysis of the amplified exons of the insulin receptor gene showed a silent mutation in patient 1 at codon Ser339, changing AGT to AGC. In patient 2 a heterozygous Met for Val substitution at position 985 was detected, which is a rare polymorphism. In patient 3 no mutations, other than described polymorphisms, were observed. These findings demonstrate that the primary genetic lesion in Seip-Berardinelli's lipodystrophy is outside the insulin receptor gene and that an involvement of the insulin-like growth factor I receptor is also unlikely.

Diabetes mellitus and lipoatrophy.

Insulin resistance may occur in a wide variety of conditions. Some conditions such as obesity or the presence of insulin antibodies are common. We have reported three unusual cases in which the patients exhibited marked insulin resistance, absence of subcutaneous fat, absence of ketosis, and substantial hyperglycemia despite normal insulin levels.