Molecular Cloning, Genomic Organization, and Expression of a Testicular Isoform of Hormone-Sensitive Lipase

By catalyzing the rate-limiting step in adipose tissue lipolysis, hormone-sensitive lipase (HSL) is an important regulator of energy homeostasis. The role and importance of HSL in tissues other than adipose are poorly understood. We report here the cloning and expression of a testicular isoform, designated HSL_tes. Due to an addition of amino acids at the NH₂-termini, rat and human HSL_tesconsist of 1068 and 1076 amino acids, respectively, compared to the 768 and 775 amino acids, respectively, of the adipocyte isoform (HSL_adi). A novel exon of 1.2 kb, encoding the human testis-specific amino acids, was isolated and mapped to the HSL gene, 16 kb upstream of the exons encoding HSL_adi. The transcribed mRNA of 3.9 kb was specifically expressed in testis. No significant similarity with other known proteins was found for the testis-specific sequence. The amino acid composition differs from the HSL_adisequence, with a notable hydrophilic character and a high content of prolines and glutamines. COS cells, transfected by the 3.9-kb human testis cDNA, expressed a protein of the expected molecular mass (M_r≈ 120,000) that exhibited catalytic activity similar to that of HSL_adi. Immunocytochemistry localized HSL to elongating spermatids and spermatozoa; HSL was not detected in interstitial cells.     

Three highly divergent subfamilies of the impala transposable element coexist in the genome of the fungus Fusarium oxysporum

The transposable element impala is a member of the widespread superfamily of Tc1-mariner transposons, identified in the genome of the plant pathogenic fungus Fusarium oxysporum. This element is present in a low copy number and is actively transposed in the F.␣oxysporum strain F24 that is pathogenic for melons. The structure of the impala family was investigated by cloning and sequencing all the genomic copies. The analysis revealed that this family is composed of full-length and truncated copies. Four copies contained a long open reading frame that could potentially encode a transposase of 340 amino acids. The presence of conserved functional domains (a nuclear localisation signal, a catalytic DDE domain and a DNA-binding domain) suggests that these four copies may be autonomous elements. Sequence comparisons and phylogenetic analysis of the impala copies defined three subfamilies, which differ by a high level of nucleotide polymorphism (around 20%). The coexistence of these divergent subfamilies in the same genome may indicate that the impala family is of ancient origin and/or that it arose by successive horizontal transmission events. Received: 2 December 1997 / Accepted: 28 April 1998     

Fot1, a new family of fungal transposable elements

Summary We report here the discovery of a family of transposable elements, which we refer to as Fotl elements, in the fungal plant pathogen Fusarium oxysporum. The first element was identified as an insertion in the gene encoding nitrate reductase. It is 1928 by long, has 44 by inverted terminal repeats, contains a large open reading frame and is flanked by a 2 by (TA) target site duplication. This element shares significant structural similarities with a class of transposons that includes Tc1 from Caenorhabditis elegans and therefore represents a new class of transposable elements in fungi.     

Caloric Restriction and Diet-Induced Weight Loss Do Not Induce Browning of Human Subcutaneous White Adipose Tissue in Women and Men with Obesity

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Chronic TNFα and cAMP pre-treatment of human adipocytes alter HSL, ATGL and perilipin to regulate basal and stimulated lipolysis

We examined the effects of chronic TNFα and dibutyryl-cAMP (Db-cAMP) pre-treatment on the lipolytic machinery of human hMADS adipocytes. TNFα decreased adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) protein content and triglycerides (TG)-hydrolase activity but increased basal lipolysis due to a marked reduction in perilipin (PLIN) protein content. Conversely, Db-cAMP increased ATGL and HSL protein content but prevented PLIN phosphorylation, the net result being accentuated basal lipolysis. In forskolin-stimulated conditions, TNFα and Db-cAMP pre-treatment decreased stimulated TG-hydrolase activity and impaired PLIN phosphorylation. Together, this resulted in a severely attenuated response to forskolin-stimulated lipolysis.