Human glucokinase gene: isolation, structural characterization, and identification of a microsatellite repeat...

Area of Science:

• Human molecular genetics
• Gene structure and regulation
• Metabolic disease research

Background:

• Human glucokinase (GCK) is crucial for glucose sensing in pancreatic beta-cells and liver metabolism.
• Understanding GCK gene structure and regulation is vital for metabolic disease research, particularly noninsulin-dependent diabetes mellitus (NIDDM).
• Previous studies identified multiple GCK mRNA isoforms, but their genetic basis was unclear.

Purpose of the Study:

• To isolate and characterize the human glucokinase gene.
• To elucidate the mechanisms generating GCK mRNA isoforms.
• To identify genetic markers for studying GCK defects and NIDDM susceptibility.

Main Methods:

• Gene isolation and characterization using Southern blotting.
• Analysis of gene structure, including exons, introns, and promoter regions.
• Identification and characterization of a novel polymorphic microsatellite marker using PCR-based assays.

Main Results:

• The human GCK gene exists as a single copy on chromosome 7p and contains 12 exons.
• Two tissue-specific first exons (1B for islets, 1H for liver) and an optional cassette exon drive isoform generation via alternative splicing and promoter activation.
• A novel polymorphic microsatellite marker was identified upstream of the islet promoter, with seven alleles found in American Blacks.

Conclusions:

• The diverse GCK mRNA isoforms result from tissue-specific promoter usage and alternative splicing.
• The identified polymorphic marker provides a tool for investigating the molecular basis of GCK defects.
• This genetic information will advance the understanding of glucokinase's role in NIDDM and genetic susceptibility to metabolic diseases.