Deficiency of a lipid droplet protein, perilipin 5, suppresses myocardial lipid accumulation, thereby preventing type 1 diabetes-induced heart malfunction.

Lipid droplet (LD) is a ubiquitous organelle that stores triacylglycerol and other neutral lipids. Perilipin 5 (Plin5), a member of the perilipin protein family that is abundantly expressed in the heart, is essential to protect LDs from attack by lipases, including adipose triglyceride lipase. Plin5 controls heart metabolism and performance by maintaining LDs under physiological conditions.

Perilipin 5, a lipid droplet-binding protein, protects heart from oxidative burden by sequestering fatty acid from excessive oxidation.

Lipid droplets (LDs) are ubiquitous organelles storing neutral lipids, including triacylglycerol (TAG) and cholesterol ester. The properties of LDs vary greatly among tissues, and LD-binding proteins, the perilipin family in particular, play critical roles in determining such diversity. Overaccumulation of TAG in LDs of non-adipose tissues may cause lipotoxicity, leading to diseases such as diabetes and cardiomyopathy.

GATA4 is involved in the gonadal development and maturation of the teleost fish tilapia, Oreochromis niloticus.

GATA4, a member of the GATA family, is a well-known transcription factor implicated in the regulation of sex determination and sexual differentiation in mammals. However, little is known about the possible role of GATA4 in fish reproduction. In the present study, a full-length GATA4 cDNA from the tilapia was cloned and characterized.

Doublesex- and Mab-3-related transcription factor-1 repression of aromatase transcription, a possible mechanism favoring the male pathway in tilapia.

Doublesex- and Mab-3-related transcription factor-1 (Dmrt1) is an important transcription factor implicated in early testicular differentiation in vertebrates, but its target genes are largely unknown. In the Nile tilapia, estrogen is the natural inducer of ovarian differentiation. Our recent studies have shown that Forkhead-l2 up-regulated transcription of the Cyp19a1a gene (aromatase) in the gonads in a female-specific manner.

Stability in aromatase immunoreactivity of steroid-producing cells during early development of XX gonads of the Nile tilapia, Oreochromis niloticus: an organ culture study.

The organ culture system is a useful tool to study the effects of various factors on the development of undifferentiated gonads. In this study, we first established an organ culture system for gonads of all genetic male and female Nile tilapia at 5-122 days after hatching (dah). This short-term (3 days) organ culture system was then used to examine the stability of the immunoreactivity of aromatase (the enzyme which converts androgen to estrogen, thus playing a crucial role in ovarian differentiation) in steroid-producing cells (SPCs).

Sexual dimorphic expression of genes in gonads during early differentiation of a teleost fish, the Nile tilapia Oreochromis niloticus.

The Nile tilapia, a gonochoristic teleost fish with an XX/XY sex-determining system, provides an excellent model for studying gonadal sex differentiation because genetic all-females and all-males are available. In this study, we used quantitative real-time RT-PCR to determine the precise timing of the gonadal expression of 17 genes thought to be associated with gonadal sex differentiation in vertebrates. Gonads were isolated from all-female and all-male tilapia before (5-15 days after hatching [dah]) and after (25-70 dah) morphological sex differentiation.

A novel type of P450c17 lacking the lyase activity is responsible for C21-steroid biosynthesis in the fish ovary and head kidney.

Cytochrome P450c17 is the single enzyme that mediates the 17 alpha-hydroxylase and 17, 20 lyase activities during the biosynthesis of steroid hormones in the gonads and adrenal gland. However, the mechanism underlying its dual action continues to be a controversy in the field of steroidogenesis in fish. In an attempt to resolve this issue, we identified a novel type of P450c17 (P450c17-II) by an in silico analysis from the genomes of six fish species.

Foxl2 up-regulates aromatase gene transcription in a female-specific manner by binding to the promoter as well as interacting with ad4 binding protein/steroidogenic factor 1.

Increasing evidence suggests the crucial role of estrogen in ovarian differentiation of nonmammalian vertebrates including fish. The present study has investigated the plausible role of Foxl2 in ovarian differentiation through transcriptional regulation of aromatase gene, using monosex fry of tilapia. Foxl2 expression is sexually dimorphic, like Cyp19a1, colocalizing with Cyp19a1 and Ad4BP/SF-1 in the stromal cells and interstitial cells in gonads of normal XX and sex-reversed XY fish, before the occurrence of morphological sex differentiation.

Knock-down of DMY initiates female pathway in the genetic male medaka, Oryzias latipes.

DMY is the second vertebrate sex-determining gene identified from the fish, Oryzias latipes. In this study, we used two different ways of sex reversal, DMY knock-down and estradiol-17beta (E2) treatment, to determine the possible function of DMY during early gonadal sex differentiation in XY medaka. Our findings revealed that the mitotic and meiotic activities of the germ cells in the 0 day after hatching (dah) DMY knock-down XY larvae were identical to those of the normal XX larvae, suggesting the microenvironment of these XY gonads to be similar to that of the normal XX gonad, where DMY is naturally absent.

Molecular cloning of DAX1 and SHP cDNAs and their expression patterns in the Nile tilapia, Oreochromis niloticus.

Piscine DAX1 and SHP cDNAs with an open reading frame encoding 296 and 258 amino acid residues, respectively, as well as SHP partial gene fragment, were cloned from Nile tilapia. Phylogenetic analyses of DAX1s, SHPs, and homologous EST fragments indicate that DAX1 and SHP are conserved in gene structure and are present throughout vertebrates. A single band of approximately 1.

The newly identified human nuclear protein NXP-2 possesses three distinct domains, the nuclear matrix-binding, RNA-binding, and coiled-coil domains.

Using a monoclonal antibody that recognizes a nuclear matrix protein, we selected a cDNA clone from a lambdagt11 human placenta cDNA library. This cDNA encoded a 939-amino acid protein designated nuclear matrix protein NXP-2. Northern blot analysis indicated that NXP-2 was expressed in various tissues at different levels.