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E Amri

Publications and source records attributed to E Amri.

9 recordsLinked to original sources
PubMed1999

CD36 antisense expression in 3T3-F442A preadipocytes.

An adipocyte membrane glycoprotein, FAT, homologous to CD36, has been implicated in the binding/transport of long-chain fatty acids. FAT/CD36 was identified by reaction with reactive long chain fatty acids derivatives under conditions where they inhibited FA uptake. Expression of CD36 in fibroblasts lacking the protein led to induction of a saturable high affinity, phloretin-sensitive component of oleate uptake. In this report, we have examined the effects of FAT/CD36 antisense expression in 3T3-F442A preadipocyte cells, on FA uptake and cell differentiation. Cells were transfected with pSG5-TAF vector obtained by insertion of antisense coding sequence of FAT/CD36 into the BamH 1 site of pSG5. Four clones were selected based on expression of antisense CD36 mRNA. Levels of CD36 protein were determined by flow cytometry and correlated with rates of oleate uptake. Three clones, TAF13, TAF25, and TAF38 exhibited low CD36 expression and one clone TAF 18 had expression comparable to that of F442A control cells. FA uptake rates in clones TAF13, TAF25 and TAF38 were lower than those observed in TAF18. At confluence, adipocyte differentiation could be promoted by addition of insulin and triiodothyronine only in TAF18 cells but not in TAF13, TAF25 or TAF38. Addition of fatty acids to clones TAF13, TAF25 and TAF38 lead to an induction of CD36 expression, an enhancement of FA uptake and better cell differentiation. The data support a role of CD36 in the membrane uptake of long chain FA. CD36 expression and FA uptake appear to be closely linked to preadipocyte differentiation.

3T3 Cells↗
PubMed1998

[Penetrating keratoplasty in primary congenital glaucoma].

PURPOSE: We present preliminary research on penetrating keratoplasty in corneal dystrophy secondary to congenital glaucoma. The aim was to analyse the functional and anatomic results of this morbid condition where visual prognosis is usually poor. PATIENTS AND METHODS: Six cases of congenital glaucoma in which the ocular pressure is controlled were studied. Age varied from 10 months to 11 years, the medium age was 47.7 months (SD: 42.8). These patients underwent penetrating keratoplasty. Recession varied from 3 months to 29 months, with a medium recession of 18.4 months (SD: 11.54). RESULTS: Anatomic results: the graft remained transparent in 5 eyes. Some postoperative complications were noticed: ocular hypertonia medically treated in one case, minor uveitis in one case, total cataract operated by phacophagy with a final outcome of ophthalmomalacia, buphtalmia (31.5 of diameter and ocular tonus at 7 mmHg). Functional results: an amelioration of visual acuity was obtained in 5 of 6 cases. CONCLUSION: The anatomic and functional results were satisfactory. Ocular pressure must be normalised before keratoplasty. Important buphtalmia constitutes one contra-indication to this intervention. Hypotonia would appear to be a factor of poor prognosis.

Child↗
PubMed1997

Regulation of FAT/CD36 gene expression: further evidence in support of a role of the protein in fatty acid binding/transport.

Much biochemical evidence has implicated rat adipocyte CD36 (FAT) in membrane binding and transport of long-chain fatty acids (FA). Expression of the mRNA favored tissues with active FA metabolism and was upregulated in vivo with diabetes and with high fat feeding. In culture, CD36 mRNA was a strong marker of preadipocyte differentiation and was modulated by the same factors effective on mRNAs coding for other proteins involved in FA metabolism. In preadipocytes, long-chain FA or 2-bromopalmitate but not short-chain FA strongly induced CD36 mRNA within 8 h to an optimum within 24 h. Removal of the FA resulted in a decay of CD36 mRNA with a half life of about 12 h. In differentiated adipocytes, levels of CD36 mRNA were downregulated by the 3': 5'-cyclic adenosine monophosphate, cAMP, analog, 8-(4-chlorophenylthio) adenosine, 8-CPT, at concentrations of 1-100 microM. The effect, observed within 6 h, was optimal after 18 h and independent of the action of 8-CPT to mobilize FA. Regulation of CD36 expression by factors effective on expression of other proteins implicated in FA metabolism is consistent with its role in membrane FA transport.

Adipocytes↗
PubMed1990

The adipocyte: relationships between proliferation and adipose cell differentiation.

The differentiation of adipose precursor cells can be divided into early and late events. Growth arrest at the G1/S boundary triggers the activation of early genes, i.e., pOb24 and lipoprotein lipase; the expression of both genes is primarily regulated at a transcriptional level. The expression of late markers, which lead to terminal differentiation and accumulation of neutral lipids, takes place after a limited number of mitoses of early-marker-expressing cells. Only terminal differentiation requires the presence of growth hormone and triiodothyronine as obligatory hormones and insulin as a modulating hormone, and results in the formation of triacylglycerol-filled, non-dividing cells. It appears that terminal differentiation involves the cyclic AMP pathway, the diacylglycerol pathway, and a third pathway triggered by insulinlike growth factor-I and insulin. It is thus proposed that a combination of mitogenic-adipogenic signals is required to trigger terminal differentiation of preadipose cells.

Adipose Tissue↗
PubMed1989

Regulation of gene expression by insulin in adipose cells: opposite effects on adipsin and glycerophosphate dehydrogenase genes.

Insulin is known to play the role of a positive effector both in vitro on the adipose conversion process and in vivo on the fatty acid synthesis and esterification processes in adipose tissue. The effects of insulin on the expression of two genes activated during adipose conversion, glycerol-3-phosphate dehydrogenase (GPDH) and adipsin genes, have been investigated in 3T3 F442A adipose cells. Within a physiological range of concentrations, insulin exerts opposite effects on the levels of GPDH (EC50 approximately 0.2 nM) and adipsin (EC50 approximately 1 nM) mRNAs. Its negative effect on the abundance of adipsin mRNA involves primarily a rapid inhibition of the transcriptional rate (less than 2 h). Its positive effect on the abundance of GPDH mRNA is due to a stimulation of the transcriptional rate accompanied by a delayed stabilization of GPDH mRNA. In addition, insulin exerts a specific effect on the length of the poly(A) tract of the adipsin mRNA. These results show that a single mechanism for the regulation of adipose-related genes by insulin can be excluded but rather suggest a complex phenomenon in which various levels of regulation take place.

Adipose Tissue↗
PubMed1985

[Lipoprotein lipase and adipocyte differentiation].

Some hormonal factors, possibly involved in the proliferation and differentiation of adipose precursor cells in vivo, have been characterized in vitro using different preadipocyte cell lines established from rodent adipose tissue. The process of adipose conversion has also been studied using these cell lines; in this process, stem cells (adipoblasts) were committed at any cell division during the growth phase. At confluence, committed cells (preadipocytes) underwent a limited number of mitoses and differentiated into adipose cells, whereas the uncommitted cells remained as stem cells in the cell population. This stochastic model could be extended to the development of rat adipose tissue in vivo. The study of adipose conversion showed the early emergence of lipoprotein lipase (LPL) and monoglyceride lipase (MGL). LPL activity appeared in the cells before any triglyceride accumulation. In contrast, this accumulation seemed dependent upon the emergence of glycerol-3-phosphate dehydrogenase. In vitro experiments clearly established that LPL-containing (differentiating) cells underwent postconfluent mitoses. This limited proliferation was in agreement with previous data obtained in vivo and indicates that only triglyceride-containing (mature) cells could not divide.

Adipose Tissue↗
PubMedDate not supplied

Hormonal requirements for growth and differentiation of ob17 preadipocyte cells in vitro.

The ob17 cell line is a clonal line established from epididymal fat pads of C57 BL/6J ob/ob mice. After conversion into adipose-like cells, ob17 presents both the morphological and biochemical properties of mature rodent fat cells. The adipose conversion process is best represented by a stochastic model in which a pool of stem cells (adipoblasts) gives rise to clusters of adipose cells and to additional stem cells that remain in the population. The role of the different factors involved in the adipose conversion process of ob17 cells is discussed, i.e. 1) mitogenic factors, that enhance the number of committed cells (ACF or adipose conversion factor(s)) 2) lipogenic factors, that enhance the expression of adipocyte enzyme markers (insulin) and 3) adipogenic factors, that are obligatory requirements for adipose conversion (triiodothyronine, growth hormone and other pituitary factors).

Adipose Tissue↗