Steroid biosynthesis

About: Steroid biosynthesis is a research topic. Over the lifetime, 1721 publications have been published within this topic receiving 58977 citations.

Transcriptional profiling analysis of Penicillium digitatum, the causal agent of citrus green mold, unravels an inhibited ergosterol biosynthesis pathway in response to citral.

Abstract: Green mold caused by Penicillium digitatum is the most damaging postharvest diseases of citrus fruit. Previously, we have observed that citral dose-dependently inhibited the mycelial growth of P. digitatum, with the minimum inhibitory concentration (MIC) of 1.78 mg/mL, but the underlying molecular mechanism is barely understood. In this study, the transcriptional profiling of the control and 1/2MIC-citral treated P. digitatum mycelia after 30 min of exposure were analyzed by RNA-Seq. A total of 6355 genes, including 2322 up-regulated and 4033 down-regulated genes, were found to be responsive to citral. These genes were mapped to 155 KEGG pathways, mainly concerning mRNA surveillance, RNA polymerase, RNA transport, aminoacyl-tRNA biosynthesis, ABC transporter, glycolysis/gluconeogenesis, citrate cycle, oxidative phosphorylation, sulfur metabolism, nitrogen metabolism, inositol phosphate metabolism, fatty acid biosynthesis, unsaturated fatty acids biosynthesis, fatty acid metabolism, and steroid biosynthesis. Particularly, citral exposure affected the expression levels of five ergosterol biosynthetic genes (e.g. ERG7, ERG11, ERG6, ERG3 and ERG5), which corresponds well with the GC-MS results, the reduction in ergosterol content, and accumulation of massive lanosterol. In addition, ERG11, the gene responsible for lanosterol 14α-demethylase, was observed to be the key down-regulated gene in response to citral. Our present finding suggests that citral could exhibit its antifungal activity against P. digitatum by the down-regulation of ergosterol biosynthesis.

Steroid Biosynthesis in the Silkworm

Abstract: IT has already been established in the silkworm (Bombyx mori L.) that sterol is one of the biologically vital active principles in the ‘brain’ hormone1 and an important nutrient in artificial diet2.

Expression of steroid hormone receptors, their regulated proteins, and bcl-2 protein in myofibroblastoma of the breast

Abstract: Aims To investigate the possible role of steroid hormones in the pathogenesis of myofibroblastoma (MFB) of the breast, we analysed the immunohistochemical expression of oestrogen, progesterone, androgen receptors, their regulated proteins and bcl-2 protein in a series of this rare tumour. Methods and results Paraffin-embedded sections from seven cases of MFB of the breast (five male; two female) were immunohistochemically tested for the expression of oestrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), oestrogen-regulated pS2 protein, androgen-regulated prostate-specific antigen (PSA) and bcl-2 protein. Rare cases of benign spindle cell tumours or tumour-like lesions of the breast (primitive fibromatosis, inflammatory pseudotumour, muscular hamartoma) which enter into the differential diagnosis with MFB, were also investigated and compared with MFB. All cases of MFB showed a diffuse (70–90% of neoplastic cells) and strong nuclear labelling with ER and PR, whereas AR was expressed only in three cases (two men and one woman) in about 60–70% of cells. Conversely, no immunostaining was detected for the pS2 protein and PSA. bcl-2 protein immunoreactivity was found in all cases of MFB, although with a variable degree of expression. No expression for steroid hormone receptors, their regulated-proteins and bcl-2 protein was observed in the rare benign spindle cell lesions of the breast included in this study. Conclusion The in-situ detection of ER, PR and AR suggests that steroid hormones and their receptors are implicated in the pathogenesis of breast MFB. The consistent demonstration of bcl-2 protein, associated with a positive ER/PR status, provides evidence that bcl-2 may be an oestrogen-regulated protein also in MFB and that probably plays a role in the tumorigenesis. Finally, we postulate that the ER/PR and bcl-2 positive immunoprofile of MFB of the breast, in contrast to the negative profile of other rare primitive benign spindle cell lesions of the breast herein studied, might be exploited as an ancillary diagnostic aid in differential diagnosis of doubtful cases.