Identification and characterization of four splicing variants of ovine POU1F1 gene

Abstract

Expression of POU1F1 gene, a member of the POU homeodomain family of transcription factors, is necessary for normal differentiation, development and survival of three anterior pituitary cell types (thyrotrophs, somatotrophs and lactotrophs) and for the proper expression of growth hormone (GH ), prolactin (PRL), thyroid-stimulating hormone (TSH ) genes and POU1F1 gene itself. Alternative splicing forms of this gene have been reported in different species, with few functional studies. Apart from the POU1F1-Wild-type with the expected length, in this work we isolated three additional splicing variants: POU1F1-β, with a 78 bp insert in the trans-activation domain; POU1F1-γ that lacks exon 3 and POU1F1-δ that lacks exons 3, 4 and 5. Four different protein isoforms were also detected by Western blot in the sheep pituitary tissue. Functional assays were performed to study the trans-activation of GH and PRL promoters by the splicing variants. Regarding the PRL promoter, the β variant presented only 12% of the Wild-type trans-activation capacity. Variants γ and δ showed no capacity to trans-activate PRL promoter. Both γ and δ variants acted as repressors of Wt, reducing significantly the trans-activation made by Wt alone ( p < 0.05). Concerning the GH promoter, the β variant presented a trans-activation capacity 10% higher than Wt. Wt and β variants strongly interact in the activation of GH promoter doubling the trans-activation potential of Wt. Variants γ and δ showed no capacity to trans-activate the GH promoter and both acted as repressors, reducing significantly ( p < 0.001) the trans-activation performed by Wt. This work presents, for the first time, the characterization of four splicing forms of Ovis aries POU1F1 gene.

Gene expression levels in some candidate genes for mastitis resistance, milk yield,and milk quality of goats reared under different feeding systems

“…Examination of PPARγ expression levels in different feeding systems shows similar expression levels for pasture and pen groups throughout lactation other than the 1st month. Changes in milk secretion as a result of feeding during lactation occur via the PRL pathway (33); however, this influence does not generate changes in adipocytes, and therefore PPARγ expression stays constant.…”

The evolutionary relationship between gene duplication and alternative splicing

“…Even though the number of genes themselves does not increase, alternative splicing can efficiently amplify the gene variation and relative functional differentiation by producing different transcripts through a splicing mechanism (Bastos et al, 2006, Bugeon et al, 2006. In particular, the full-length cDNA projects of human and mouse have proved that these organisms have a tremendous number of splicing variants (Modrek andLee 2003, Zavolan et al, 2003).…”

A TaqI PCR-RFLP Detecting a Novel SNP in Exon 2 of the Bovine POU1F1 Gene

“…Recently, alternative splicing forms of the POU1F1 gene have been reported in different species (Bastos et al 2006). Apart from the sheep POU1F1-Wild-type with the expected length, Bastos et al (2006) isolated three additional sheep POU1F1 splice variants: POU1F1-b, POU1F1-c, and POU1F1-d. Further, concerning the GH promoter, the b variant presents a trans-activation capacity 10% higher than the wild type.…”

“…Apart from the sheep POU1F1-Wild-type with the expected length, Bastos et al (2006) isolated three additional sheep POU1F1 splice variants: POU1F1-b, POU1F1-c, and POU1F1-d. Further, concerning the GH promoter, the b variant presents a trans-activation capacity 10% higher than the wild type. Wild type and b variants strongly interact in the activation of the GH promoter, doubling the trans-activation potential of the wild type.…”