Identification of the ectoenzyme CD38 as a marker of committed preadipocytes.

BACKGROUND/OBJECTIVES: Characterisation of the adipocyte cellular lineage is required for a better understanding of white adipose tissue homoeostasis and expansion. Although several studies have focused on the phenotype of the most immature adipocyte progenitors, very few tools exist to identify committed cells. In haematopoiesis, the CD38 ectoenzyme is largely used to delineate various stages of stem cell lineage commitment. We hypothesise that this marker could be used to identify committed preadipocytes. METHODS: Complementary strategies including flow cytometry, cell-sorting approaches, immunohistochemistry and primary cultures of murine adipose progenitors isolated from different fat pads of control or high-fat diet exposed C57BL/6 J mice were used to determine the molecular expression profile, proliferative and differentiation potentials of adipose progenitors expressing the CD38 molecule. RESULTS: We demonstrate here that a subpopulation of CD45- CD31- CD34+ adipose progenitors express the cell surface protein CD38. Using a cell-sorting approach, we found that native CD45- CD31- CD34+ CD38+ (CD38+) adipose cells expressed lower CD34 mRNA and protein levels and higher levels of adipogenic genes such as Pparg, aP2, Lpl and Cd36 than did the CD45- CD31- CD34+ CD38- (CD38-) population. When cultivated, CD38+ cells displayed reduced proliferative potential, assessed by BrdU incorporation and colony-forming unit assays, and greater adipogenic potential. In vitro, both CD38 mRNA and protein levels were increased during adipogenesis and CD38- cells converted into CD38+ cells when committed to the adipogenic differentiation programme. We also found that obesity development was associated with an increase in the number of CD38+ adipose progenitors, this effect being more pronounced in intra-abdominal than in subcutaneous fat, suggesting a higher rate of adipocyte commitment in visceral depots. CONCLUSIONS: Together, these data demonstrate that CD38 represents a new marker that identifies committed preadipocytes as CD45- CD31- CD34low CD38+ cells.

Adipocyte lipases and lipid droplet-associated proteins: insight from transgenic mouse models.

Adipose tissue lipolysis is the catabolic process whereby stored triacylglycerol (TAG) is broken down by lipases into fatty acids and glycerol. Here, we review recent insights from transgenic mouse models. Genetic manipulations affecting lipases are considered first, followed by transgenic models of lipase co-factors and lastly non-lipase lipid droplet (LD)-associated proteins. The central role of hormone-sensitive lipase (HSL), long considered to be the sole rate-limiting enzyme of TAG hydrolysis, has been revised since the discovery of adipose triglyceride lipase (ATGL). It is now accepted that ATGL initiates TAG breakdown producing diacylglycerol, which is subsequently hydrolyzed by HSL. Furthermore, lipase activities are modulated by co-factors whose deletion causes severe metabolic disturbances. Another major advance has come from the description of the involvement of non-lipase proteins in the regulation of lipolysis. The role of perilipins has been extensively investigated. Other newly discovered LD-associated proteins have also been shown to regulate lipolysis.

Transcription of the human uncoupling protein 3 gene is governed by a complex interplay between the promoter and intronic sequences.

AIMS/HYPOTHESIS: Uncoupling protein (UCP) 3 is an inner mitochondrial membrane transporter mainly produced in skeletal muscle in humans. UCP3 plays a role in fatty acid metabolism and energy homeostasis and modulates insulin sensitivity. In humans, UCP3 content is higher in fast-twitch glycolytic muscle than in slow-twitch oxidative muscle and is dysregulated in type 2 diabetes. Here, we studied the molecular mechanisms determining human UCP3 levels in skeletal muscle and their regulation by fasting in transgenic mice. METHODS: We produced a series of transgenic lines with constructs bearing different putative regulatory regions of the human UCP3 gene, including promoter and intron sequences. UCP3 mRNA and reporter gene expression and activity were measured in different skeletal muscles and tissues. RESULTS: The profile of expression and the response to fasting and thyroid hormone of human UCP3 mRNA in transgenic mice with 16 kb of the human UCP3 gene were similar to that of the endogenous human gene. Various parts of the UCP3 promoter did not confer expression in transgenic lines. Inclusion of intron 1 resulted in an expression profile in skeletal muscle that was identical to that of human UCP3 mRNA. Further dissection of intron 1 revealed that distinct regions were involved in skeletal muscle expression, distribution among fibre types and response to fasting. CONCLUSIONS/INTERPRETATION: The control of human UCP3 transcription in skeletal muscle is not solely conferred by the promoter, but depends on several cis-acting elements in intron 1, suggesting a complex interplay between the promoter and intronic sequences.

[Prolapse surgery through the vagina with the help of Endo Stitch. Technical note and preliminary study]. / Cure de prolapsus par voie basse exclusive à l'aide de l'Endo Stitch. Note technique et étude préliminaire.

OBJECTIVE: Vaginal cure of genitourinary prolapses is a reliable technique. We propose a technical simplification: the use of the laparoscopic suturing instrument Endo Stitch. Bladder neck suspension can be performed in this way without supra-pubic incision. Sacrospinous suspension is sometimes difficult with a risk of sciatic nerve, pudendal artery or rectum trauma. This is also performed more easily using Endo Stitch. SUBJECTS AND METHODS: Twenty patients with genitourinary prolapse were treated by one surgeon using the Endo Stitch. The patients were followed for 6 to 18 months. RESULTS: No per- or postoperative complications attributable to the use of Endo Stitch were encountered. With two recurrent genital prolapses and one persistent urinary stress incontinence, anatomic and functional results seem to be similar to reference series, but must be confirmed with more follow-up.

Competent mouse oocytes isolated from antral follicles exhibit different chromatin organization and follow different maturation dynamics.

After labelling DNA with the specific vital fluorophore Hoechst 33342, oocytes, isolated by puncture from antral follicles in adult mice, have two essentially different configurations of their nuclear fluorescence images. These have been called SN (where the nucleolus is surrounded by chromatin) and NSN (where the nucleolus is not surrounded by chromatin). Intermediate configurations are also found, although with a lower frequency. The proportion of each class is on the average equal and depends neither on the presence of cumulus cells nor on the age of the mouse. Electron microscopy confirms several ultrastructural differences between these two nuclear configurations, namely, the structure of the nucleolus, which is vacuolated in NSN-type and compact in SN-type oocytes. Using video-enhanced fluorescence microscopy at low level of excitation light, we could follow directly in vitro the meiotic maturation of both classes, without impairing their viability. We show that in germinal vessicle (GV) state, the chromatin does not change from one configuration into the other and that both classes are able to mature to metaphase II, although the maturation has slightly different characteristics.

Psychometric procedures for analysis of memory losses in the elderly.

This study aimed to assess and compare the discriminative validity of two psychometric procedures which have been proposed to investigate memory losses in elderly. The first one relies on the use of the serial position curve paradigm in a test of immediate memory, the second one being a single recognition task. These two procedures were applied to the five following groups of subjects: 95 young-elderly normals, 33 elderly normals, 26 patients with mild senile dementia of the Alzheimer type (SDAT), 17 patients with moderate or moderately severe SDAT and 24 elderly depressed patients. Results from both psychometric procedures confirm the findings of previous studies and support the view that memory impairment associated with SDAT is qualitatively different from that observed in normal aging or in depression. They also suggest that memory loss in elderly depressed patients differs only quantitatively from that of normal controls. However the recognition task seems to have the best validity to qualitatively discriminate the patients with mild dementia from both the normal controls and the elderly depressed patients.