Molecular biology of islet amyloid polypeptide.
We investigated the relationship between non-insulin-dependent diabetes mellitus (NIDDM) and islet amyloid polypeptide (IAPP) gene by restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR)-direct sequencing analysis. Endonuclease BglII and/or PvuII RFLP analysis revealed no positive correlation of IAPP gene with NIDDM. In PCR-direct sequencing of 25 NIDDM patients, no nucleotide sequence differences were found. These data do not support the view that IAPP plays an important role in the pathogenesis of NIDDM. cDNAs encoding cat, rat, mouse, guinea pig and degu IAPP precursors were also cloned, and comparison of these predicted amino acid sequences clarified the species difference, especially between amyloid-forming and non-amyloid-forming species. Amino acid residues 25-28 of mature IAPP might be responsible for their amyloidogeneity. The alternative splicing transcripts of guinea pig IAPP gene were identified by using PCR. If these types of transcripts are translated, N-terminal mutated IAPP might be produced and act as an antagonist. The signal peptide cleavage site of rat IAPP precursor was also identified by an in vitro translation and processing system.
Nishi
M
M
First Department of Medicine, Wakayama University of Medical Science, Japan.
Sanke
T
T
Ohagi
S
S
Ekawa
K
K
Wakasaki
H
H
Nanjo
K
K
Bell
G I
GI
Steiner
D F
DF
D000595:Amino Acid Sequence; D000682:Amyloid / Q000235:genetics*; D000818:Animals; D001426:Bacterial Proteins; D001483:Base Sequence; D002415:Cats; D003001:Cloning, Molecular; D015252:Deoxyribonucleases, Type II Site-Specific; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D006168:Guinea Pigs; D006801:Humans; D007340:Insulinoma / Q000235:genetics; D058228:Islet Amyloid Polypeptide; D007962:Leukocytes / Q000502:physiology; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010190:Pancreatic Neoplasms / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012326:RNA Splicing; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D000682:Amyloid; D001426:Bacterial Proteins; D058228:Islet Amyloid Polypeptide; D009838:Oligodeoxyribonucleotides; D012313:RNA; C024404:BglII endonuclease; C025630:CAGCTG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific