English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Insulin-like growth factor I (IGF-I) and the gonadotropin, FSH, can synergize to stimulate progesterone production in primary cultures of maturing granulosa cells. These trophic hormones increase low density lipoprotein (LDL) receptor binding and internalization, and the utilization of LDL-borne cholesterol by granulosa cells. To determine whether and how IGF-I and FSH control the genomic expression of the LDL receptor, we evaluated their individual and concerted effects on LDL receptor messenger RNA (mRNA) accumulation, stability, and gene promoter activity in first passage monolayer (serum-free) cultures of porcine granulosa cells. Ribonuclease protection assays revealed that LDL receptor mRNA accumulation was increased by human recombinant IGF-I (100 ng/ml), FSH (25 ng/ml NIDDK oFSH-20), or their combination by 2.2-, 2.6-, and 4.6-fold, respectively (P &lt; 0.01). Hormonally stimulated LDL receptor mRNA accumulation was suppressed by 54-75% by the concurrent addition of LDL substrate (50 microg/ml). The combination of FSH and IGF-I significantly prolonged the message half-life, even in the presence of LDL. Using a combination of rapid amplification of cDNA 5'-ends, PCR with adapter-ligated genomic DNA, Southern hybridization, and DNA sequencing, we isolated 1076 bp of the porcine LDL receptor gene upstream of the coding region. In transient transfection assays, with a pLDLR1076/luciferase plasmid construct, FSH, FSH plus IGF-I, or 8-bromo-cAMP (1 mM) treatment (but not IGF-I alone) increased luciferase reporter gene activity by 10- to 23-fold in porcine granulosa cells. Over time in serum-free culture, the basal activity of the LDL receptor gene promoter increased and eventually surpassed hormone-stimulated effects, but was suppressed by LDL substrate (by 75%) at 24 h. The foregoing stimulatory hormone effects and sterol repression were localized to a 116-bp region in the porcine promoter between -255 and -139 upstream of the translational start site. We conclude that the combination of FSH and IGF-I can induce accumulation of LDL receptor mRNA in cultured granulosa cells even in the presence of sterol negative feedback and can do so mechanistically by a combination of promoter activation and increased mRNA stability.

endocrinology

Concerted Regulation of Low Density Lipoprotein Receptor Gene Expression by Follicle-Stimulating Hormone and Insulin-Like Growth Factor I in Porcine Granulosa Cells: Promoter Activation, Messenger Ribonucleic Acid Stability, and Sterol Feedback<sup>1</sup>

Concerted Regulation of Low Density Lipoprotein Receptor Gene Expression by Follicle-Stimulating Hormone and Insulin-Like Growth Factor I in Porcine Granulosa Cells: Promoter Activation, Messenger Ribonucleic Acid Stability, and Sterol Feedback1

Concerted Regulation of Low Density Lipoprotein Receptor Gene Expression by Follicle-Stimulating Hormone and Insulin-Like Growth Factor I in Porcine Granulosa Cells: Promoter Activation, Messenger Ribonucleic Acid Stability, and Sterol Feedback¹