Immature transformed rat islet beta-cells differentially express C-peptides derived from the genes coding for insulin I and II as well as a transfected human insulin gene

TY - JOUR

T1 - Immature transformed rat islet beta-cells differentially express C-peptides derived from the genes coding for insulin I and II as well as a transfected human insulin gene

AU - Blume, N

AU - Petersen, J S

AU - Andersen, L C

AU - Kofod, Hans

AU - Dyrberg, T

AU - Michelsen, B K

AU - Serup, P

AU - Madsen, O D

PY - 1992/2

Y1 - 1992/2

N2 - Synthetic peptides representing unique sequences in rat proinsulin C-peptide I and II were used to generate highly specific antisera, which, when applied on sections of normal rat pancreas, confirm a homogeneous coexpression of the two C-peptides in all islet beta-cells. Insulin gene expression is induced in the transformed heterogeneous rat islet cell clone, NHI-6F, by transient in vivo passage. During this process a transfected human insulin gene is coactivated with the endogenous nonallelic rat insulin I and II genes. Newly established cultures from NHI-6F insulinomas having a high frequency of insulin-producing cells showed highly differential expression at the cellular level of the three proinsulin C-peptide immunoreactivities, as follows: C-peptide I greater than human C-peptide greater than C-peptide II. The fractions of cells expressing human C-peptide and C-peptide II decreased in time and were absent after more than 50 successive passages, while a C-peptide I-producing population was still present. Double-labeling experiments revealed a heterogeneous distribution of the three different C-peptides. Surprisingly, in the early passages a large fraction of cells would express only a single species of proinsulin-C-peptide immunoreactivity but still at high levels. However, rat C-peptide II and human C-peptide were often colocalized, even in later passages. In situ hybridization studies combined with the immunocytochemical data suggest that the differential expression occurs at the level of transcription.(ABSTRACT TRUNCATED AT 250 WORDS)

AB - Synthetic peptides representing unique sequences in rat proinsulin C-peptide I and II were used to generate highly specific antisera, which, when applied on sections of normal rat pancreas, confirm a homogeneous coexpression of the two C-peptides in all islet beta-cells. Insulin gene expression is induced in the transformed heterogeneous rat islet cell clone, NHI-6F, by transient in vivo passage. During this process a transfected human insulin gene is coactivated with the endogenous nonallelic rat insulin I and II genes. Newly established cultures from NHI-6F insulinomas having a high frequency of insulin-producing cells showed highly differential expression at the cellular level of the three proinsulin C-peptide immunoreactivities, as follows: C-peptide I greater than human C-peptide greater than C-peptide II. The fractions of cells expressing human C-peptide and C-peptide II decreased in time and were absent after more than 50 successive passages, while a C-peptide I-producing population was still present. Double-labeling experiments revealed a heterogeneous distribution of the three different C-peptides. Surprisingly, in the early passages a large fraction of cells would express only a single species of proinsulin-C-peptide immunoreactivity but still at high levels. However, rat C-peptide II and human C-peptide were often colocalized, even in later passages. In situ hybridization studies combined with the immunocytochemical data suggest that the differential expression occurs at the level of transcription.(ABSTRACT TRUNCATED AT 250 WORDS)

KW - Animals

KW - Antibodies, Monoclonal

KW - Base Sequence

KW - C-Peptide

KW - Cell Line, Transformed

KW - Enzyme-Linked Immunosorbent Assay

KW - Gene Expression Regulation

KW - Humans

KW - Immunoenzyme Techniques

KW - Insulin

KW - Islets of Langerhans

KW - Mice

KW - Molecular Sequence Data

KW - Nucleic Acid Hybridization

KW - Rats

KW - Transcription, Genetic

KW - Transfection

M3 - Journal article

C2 - 1569972

SN - 0888-8809

VL - 6

SP - 299

EP - 307

JO - Molecular Endocrinology

JF - Molecular Endocrinology

IS - 2

ER -