BIOCHEMICAL
Vol. 167, No. 3, 1990 March 30, 1990
TRANSFECTION
Masashi Yuikio
OF cDNA WITH G+T POINT INSULIN RECEPTORS
Kobayashi. Shigeta,
Third
30,
Toshiyasu Nakamura*.
SITE
OF
Sasaoka. Katsuya Egawa, and Hiroshi Teraoka*
Department of Medicine, University of Medical Science, Oh tsu, Japan
*Shionogi
January
MUTATION AT THE CLEAVAGE TO COS 7 CELLS
Masaaki Sugibayashi. Mikio Tamaki*, Etsuo
Shiga
Received
AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages 1073-1078
Research Laboratories, Shionogi & Co. Ltd., Osaka, Japan
1990
To study whether the G+T point mutation of insulin proreceptors at the cleavage site which changed -Arg-Lys-Arg-Argto -Arg-Lys-Arg-Sercaused 7 unprocessed insulin receptors with decreased insulin binding affinity. we performed transfection of cDNA with the mutation in COS 7 cells and examined the expressed insulin receptors. After site-directed mutagenesis, an expression vector pGEM3SV was used to make a plasmid which contained fulllength HIRcDNA behind SV40 early promoter. Transfection of normal HIR cDNA produced normal insulin receptors on the plasma membranes in COS 7 cells. However, transfection of cDNA with the mutation resulted in the presence of 210K proreceptors in the plasma membranes with decreased insulin binding ability (35% of normal). These results suggest that the mutation, not the defect of converting enzyme, was the cause for unprocessed insulin proreceptors in the patients with insulin resistance. 0 1990 Academic Press. Inc.
We caused
by
cleavage site
previously unprocessed site
from
by
ability
receptor
structure
However,
it
still
or
the
enzyme unprocessed
the
trypsin
insulin
Arg-Lys-Arg-Ser of
than
remained
to
be
at
the
proreceptors.
to
the
structure
point
clarified
whether
cleavage we
site performed
of not
be
and
appeared the was
cleaved
cleavage
site
and
the
to
cause
transfection
the
be
normal.
processing for
the
of
cDNA
0006-291x/90 1073
by
Therefore,
abnormal the
the
cleavage
B-subunit,
(3.4).
was at
the
abnormal
normalized site
which
mutation
could
The
a-subunit
cleavage
Thus,
due
patients.
were
the
resistance
which
normal
action
other
mutation
the
produce
insulin
insulin
changed
cells to
with
proreceptors
mutation to
in
and
siblings
insulin _ The
enzyme
cleaved
binding
(1.2)
the
Arg-Lys-Arg-Arg
processing was
reported
$1.50
Copyright 0 1990 by Academic Press, Inc. All rights of reproduction in any form reserved.
Vol. 167, No. 3, 1990 with
the
mutation
BIOCHEMICAL to
COS
7
cells
AND BIOPHYSICAL RESEARCH COMMUNICATIONS and
examined
the
expressed
insulin
receptors. Materials
and
Methods
Materials:Purified porcine insulin was a gift from Shimizu Phamaceutical Co (Shizuoka. Japan). Na [ ‘“‘I] was purchased from New England Nuclear (Boston, MA, USA), Dulbecco’s Eagles medium and fetal calf serum (FCS) from Gibco Biological Co (Grand Island, NY, USA), disuccinimydyl suberate (DSS) from Pierce-Chemical Co (Rockford Ill. USA), Protein A (Pansorbin) was from Calbiochem-Behring Co (La Jolla, CA, USA), wheat germ agglutinin (WGA) agarose from Pharmacia PL Biochemical Co (Uppsala. Sweden). receptors cDNA was kindly supplied by Dr. G.I. Bell of Chicago Insulin University and COS 7 cells by Dr. Sokawa of Kyoto University, Japan. All the restriction enzymes were purchased from Takara Shuzo Co.(Kyoto, Japan). DNA manipulations DNA manipulation:All were carried out by standard procedure (5). A eukaryotic expression vector, designated pCEM3SV. was constructed from pGEM3 and pKSV-10. A full-length cDNA of HIR carrying 130 bp and 940 bp of 5’and 3’-noncoding region, respectively. was prepared. This DNA fragment containing the entire coding sequence of HIR cDNA was blunt-ended with the Klenow enzyme and inserted into an expression vector pGEM3. after the BgllI site had been made blunt. The resulting plasmid was named pCEM3SVHIR and contained full-length HIR cDNA behind the SV40 early promotor, splicing and polyadenylation signals, and sv40 origin of replication (Figure 1). Site-directed in vitro mutagenesis:The BamHI-PstI fragment (586bp) containing the coding sequence for a normal connecting peptide between Qand B-subunits was subcloned into M13mplO;single-stranded DNA from this recombinant was used as template for oligonucleotide-directed phase mutagenesis (6). The oligonucleotide used was 5’ GGAAACGCAGTTCCCTTGGCG 3’ to create an Arg-tSer mutation as detected in the patient as prevously reported (1). A mutant Ml3 plaque was identified and the double-stranded replicative form was isolated. The BamHIPstI fragment was then cloned into BamHI/PstIcleaved pGEM3SV-HIR and the resulting plasmid pGEM3SV-HIR with mutated cDNA was used for transfection. The structure of mutant plasmid was verified by restriction enzyme analysis and nucleotide sequencing.
Figure DNA
of
1. The structure the plasmid
is
of plasmid. described
in
pCEM3SV-HIR. Method.
1074
The
method
to
construct
the
Vol.
167,
No.
BIOCHEMICAL
3, 1990
AND
BIOPHYSICAL
RESEARCH
COMMUNICATIONS
Cells and transfection:COS 7 cells were grown in Dulbecco’s Eagles medium supplemented with 10% fetal calf serum. Cells were transfected with 5 ug plasmid DNA per lo5 cells, using DEAE dextran method (7). Insulin binding and analysis of insulin receptors:Insulin binding and surface labeling of cells and subsequent analysis of insulin receptors by electrophoresis after preparation of partially purified insulin receptors were reported (1,2,3). Insulin binding in a previously was performed monolayer in the 6 well dishes and was normalized to percent bound to 10’ cells.
Results After
transfection
perfomed 72 hrs gradually.
in after
these
with
normal
transfected
transfection The
cells
cells.
with without
1 0
or
Insulin
normal
cDNA.
mutated
or
transfection
binding
mutated
insulin
reached cDNA and
showed
very
low
binding the
then
was
maximal it
insulin
decreased
binding
,’ 24
48
72
96
120
144 hours
to COS 7 cells after transfection 2. Time course of insulin binding with Intact (C--O) or mutated ( e--m ) HIR cDNA. Percentage binding shown in the vertical axis indicates percent binding over that shown in the COS 7 cells without transfection. The binding data of those in COS 7 cells without transfection were defined as 100%. Data represent mean f SEM. There were significant differences (p
Vol. 167, No. 3, 1990 March 30, 1990
TRANSFECTION
Masashi Yuikio
OF cDNA WITH G+T POINT INSULIN RECEPTORS
Kobayashi. Shigeta,
Third
30,
Toshiyasu Nakamura*.
SITE
OF
Sasaoka. Katsuya Egawa, and Hiroshi Teraoka*
Department of Medicine, University of Medical Science, Oh tsu, Japan
*Shionogi
January
MUTATION AT THE CLEAVAGE TO COS 7 CELLS
Masaaki Sugibayashi. Mikio Tamaki*, Etsuo
Shiga
Received
AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages 1073-1078
Research Laboratories, Shionogi & Co. Ltd., Osaka, Japan
1990
To study whether the G+T point mutation of insulin proreceptors at the cleavage site which changed -Arg-Lys-Arg-Argto -Arg-Lys-Arg-Sercaused 7 unprocessed insulin receptors with decreased insulin binding affinity. we performed transfection of cDNA with the mutation in COS 7 cells and examined the expressed insulin receptors. After site-directed mutagenesis, an expression vector pGEM3SV was used to make a plasmid which contained fulllength HIRcDNA behind SV40 early promoter. Transfection of normal HIR cDNA produced normal insulin receptors on the plasma membranes in COS 7 cells. However, transfection of cDNA with the mutation resulted in the presence of 210K proreceptors in the plasma membranes with decreased insulin binding ability (35% of normal). These results suggest that the mutation, not the defect of converting enzyme, was the cause for unprocessed insulin proreceptors in the patients with insulin resistance. 0 1990 Academic Press. Inc.
We caused
by
cleavage site
previously unprocessed site
from
by
ability
receptor
structure
However,
it
still
or
the
enzyme unprocessed
the
trypsin
insulin
Arg-Lys-Arg-Ser of
than
remained
to
be
at
the
proreceptors.
to
the
structure
point
clarified
whether
cleavage we
site performed
of not
be
and
appeared the was
cleaved
cleavage
site
and
the
to
cause
transfection
the
be
normal.
processing for
the
of
cDNA
0006-291x/90 1073
by
Therefore,
abnormal the
the
cleavage
B-subunit,
(3.4).
was at
the
abnormal
normalized site
which
mutation
could
The
a-subunit
cleavage
Thus,
due
patients.
were
the
resistance
which
normal
action
other
mutation
the
produce
insulin
insulin
changed
cells to
with
proreceptors
mutation to
in
and
siblings
insulin _ The
enzyme
cleaved
binding
(1.2)
the
Arg-Lys-Arg-Arg
processing was
reported
$1.50
Copyright 0 1990 by Academic Press, Inc. All rights of reproduction in any form reserved.
Vol. 167, No. 3, 1990 with
the
mutation
BIOCHEMICAL to
COS
7
cells
AND BIOPHYSICAL RESEARCH COMMUNICATIONS and
examined
the
expressed
insulin
receptors. Materials
and
Methods
Materials:Purified porcine insulin was a gift from Shimizu Phamaceutical Co (Shizuoka. Japan). Na [ ‘“‘I] was purchased from New England Nuclear (Boston, MA, USA), Dulbecco’s Eagles medium and fetal calf serum (FCS) from Gibco Biological Co (Grand Island, NY, USA), disuccinimydyl suberate (DSS) from Pierce-Chemical Co (Rockford Ill. USA), Protein A (Pansorbin) was from Calbiochem-Behring Co (La Jolla, CA, USA), wheat germ agglutinin (WGA) agarose from Pharmacia PL Biochemical Co (Uppsala. Sweden). receptors cDNA was kindly supplied by Dr. G.I. Bell of Chicago Insulin University and COS 7 cells by Dr. Sokawa of Kyoto University, Japan. All the restriction enzymes were purchased from Takara Shuzo Co.(Kyoto, Japan). DNA manipulations DNA manipulation:All were carried out by standard procedure (5). A eukaryotic expression vector, designated pCEM3SV. was constructed from pGEM3 and pKSV-10. A full-length cDNA of HIR carrying 130 bp and 940 bp of 5’and 3’-noncoding region, respectively. was prepared. This DNA fragment containing the entire coding sequence of HIR cDNA was blunt-ended with the Klenow enzyme and inserted into an expression vector pGEM3. after the BgllI site had been made blunt. The resulting plasmid was named pCEM3SVHIR and contained full-length HIR cDNA behind the SV40 early promotor, splicing and polyadenylation signals, and sv40 origin of replication (Figure 1). Site-directed in vitro mutagenesis:The BamHI-PstI fragment (586bp) containing the coding sequence for a normal connecting peptide between Qand B-subunits was subcloned into M13mplO;single-stranded DNA from this recombinant was used as template for oligonucleotide-directed phase mutagenesis (6). The oligonucleotide used was 5’ GGAAACGCAGTTCCCTTGGCG 3’ to create an Arg-tSer mutation as detected in the patient as prevously reported (1). A mutant Ml3 plaque was identified and the double-stranded replicative form was isolated. The BamHIPstI fragment was then cloned into BamHI/PstIcleaved pGEM3SV-HIR and the resulting plasmid pGEM3SV-HIR with mutated cDNA was used for transfection. The structure of mutant plasmid was verified by restriction enzyme analysis and nucleotide sequencing.
Figure DNA
of
1. The structure the plasmid
is
of plasmid. described
in
pCEM3SV-HIR. Method.
1074
The
method
to
construct
the
Vol.
167,
No.
BIOCHEMICAL
3, 1990
AND
BIOPHYSICAL
RESEARCH
COMMUNICATIONS
Cells and transfection:COS 7 cells were grown in Dulbecco’s Eagles medium supplemented with 10% fetal calf serum. Cells were transfected with 5 ug plasmid DNA per lo5 cells, using DEAE dextran method (7). Insulin binding and analysis of insulin receptors:Insulin binding and surface labeling of cells and subsequent analysis of insulin receptors by electrophoresis after preparation of partially purified insulin receptors were reported (1,2,3). Insulin binding in a previously was performed monolayer in the 6 well dishes and was normalized to percent bound to 10’ cells.
Results After
transfection
perfomed 72 hrs gradually.
in after
these
with
normal
transfected
transfection The
cells
cells.
with without
1 0
or
Insulin
normal
cDNA.
mutated
or
transfection
binding
mutated
insulin
reached cDNA and
showed
very
low
binding the
then
was
maximal it
insulin
decreased
binding
,’ 24
48
72
96
120
144 hours
to COS 7 cells after transfection 2. Time course of insulin binding with Intact (C--O) or mutated ( e--m ) HIR cDNA. Percentage binding shown in the vertical axis indicates percent binding over that shown in the COS 7 cells without transfection. The binding data of those in COS 7 cells without transfection were defined as 100%. Data represent mean f SEM. There were significant differences (p
