Evidence that biological activity of NGF is mediated through a novel subclass of high affinity receptors

Recently, several quadruplex-DNA-forming sequences have been identified in the insulin-linked polymorphic region (ILPR), which is a guanine-rich oligonucleotide sequence in the promoter region of insulin. The formation of this non-canonical quadruplex DNA (G4-DNA) has been shown to be involved in the biological activity of the ILPR, specifically with regard to its interplay with insulin. In this context, this contribution reports on the investigation of the association of the quadruplex-forming ILPR sequence a2 with insulin as well as with the well-known G4-DNA ligand 3,11-difluoro-6,8,13-trimethyl-8H-quino[4,3,2-kl]acridinium (1), also named RHPS4, by optical and NMR spectroscopy. CD- and NMR-spectroscopic measurements confirmed the preferential formation of an antiparallel quadruplex structure of a2 with four stacked guanine quartets. Furthermore, ligand 1 has high affinity toward a2 and binds by terminal π stacking to the G1–G11–G15–G25 quartet. In addition, the spectroscopic studies pointed to an association of insulin to the deoxyribose backbone of the loops of a2.

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High-affinity binding of PDGF-AA and PDGF-BB to normal human osteoblastic cells and modulation by interleukin-1

AJP Cell Physiology ◽

10.1152/ajpcell.1991.261.6.c980 ◽

1991 ◽

Vol 261 (6) ◽

pp. C980-C985 ◽

Cited By ~ 39

Author(s):

R. S. Gilardetti ◽

M. S. Chaibi ◽

J. Stroumza ◽

S. R. Williams ◽

H. N. Antoniades ◽

...

Keyword(s):

Biological Activity ◽

Growth Factors ◽

Binding Sites ◽

Thymidine Incorporation ◽

Interleukin 1 ◽

Biologically Active ◽

Osteoblastic Cells ◽

High Affinity ◽

Normal Human ◽

Human Osteoblastic Cells

Bone has the capacity for repair and regeneration. The repair process is thought to be locally regulated by growth factors. One of the growth factors that potentially plays a significant role in these processes is platelet-derived growth factor (PDGF). Two different PDGF genes have been identified, PDGF-A and PDGF-B, whose gene products give rise to biologically active dimers. We now report that PDGF-AA and PDGF-BB exhibit saturable binding to normal human osteoblastic cells. By Scatchard analysis we estimate that there are approximately 43,000 PDGF-AA binding sites per cell, with a dissociation constant (Kd) of 2.2 x 10(-10)M, and 55,000 high-affinity PDGF-BB binding sites per cell, with a Kd of 1.2 x 10(-10)M. The functional consequence of PDGF binding was also assessed. PDGF-AA and PDGF-BB both stimulated migration of normal human osteoblastic cells and stimulated thymidine incorporation. To gain insight into potential transmodulation of the PDGF response, we investigated the capacity of interleukin-1 beta (IL-1 beta), a cytokine that induces bone resorption, to modulate PDGF binding and PDGF-induced biological activity. IL-1 beta significantly reduced PDGF-AA binding and significantly decreased both PDGF-AA-mediated cell migration and thymidine incorporation. In contrast, IL-1 beta had only a small effect of PDGF-BB binding and PDGF-BB-induced biological activity in normal human osteoblastic cells.

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Cholecystokinin receptors in the brain: characterization and distribution

Science ◽

10.1126/science.6246582 ◽

1980 ◽

Vol 208 (4448) ◽

pp. 1155-1156 ◽

Cited By ~ 343

Author(s):

A Saito ◽

H Sankaran ◽

ID Goldfine ◽

JA Williams

Keyword(s):

Biological Activity ◽

Rat Brain ◽

Dissociation Constant ◽

Binding Sites ◽

Brain Regions ◽

High Affinity ◽

Cholecystokinin Receptors ◽

Iodine 125 ◽

The Brain

Specific cholecystokinin binding sites in particulate fractions of rat brain were measured with iodine 125-labeled Bolton-Hunter cholecystokinin, a cholecystokinin analog that has full biological activity. Binding was detected in brain regions known to contain immunoreactive cholecystokinin. Binding was saturable, reversible, of high affinity (dissociation constant, 1.7 x 10(-9) M), and was inhibited by cholecystokinin analogs but not by unrelated hormones.

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