High-level salivary gland expression in transgenic mice

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Previous studies showed limited parotid secretory protein (PSP) gene expression in transgenic mice.
• A 7.1 kb mini-gene construct directed salivary gland-specific mRNA expression but at low levels.
• This suggested essential regulatory elements for high-level expression were missing.

Purpose of the Study:

• To identify regulatory elements responsible for high-level parotid secretory protein (PSP) expression.
• To investigate the role of flanking sequences in controlling PSP gene expression.
• To enhance transgene expression to endogenous levels in salivary glands.

Main Methods:

• Utilized a larger 25 kb transgene construct containing the complete murine PSPb gene with extensive 5' and 3' flanking sequences.
• Employed allele-specific oligonucleotide detection to differentiate transgene mRNA from endogenous Pspa mRNA.
• Examined transgene expression in transgenic mice homozygous for the Pspa allele.

Main Results:

• Three independent transgenic mouse lines were generated with the larger PSPb transgene.
• All three lines demonstrated high-level, parotid-gland-specific expression of the transgene.
• Transgene expression levels closely matched endogenous PSP mRNA levels in the parotid gland.

Conclusions:

• The genomic DNA fragment used as a transgene contains the necessary sequences for high-level PSP mRNA expression.
• Regulatory elements crucial for achieving endogenous expression levels are located within the cloned 25 kb Pspb fragment.
• Further investigation into these identified sequences can elucidate mechanisms of salivary gland-specific gene regulation.