1 research outputs found
Conjugation of Cell-Penetrating Peptides to Parathyroid Hormone Affects Its Structure, Potency, and Transepithelial Permeation
Delivery
of therapeutic peptides and proteins by the use of cell-penetrating
peptides (CPPs) as carriers has been suggested as a feasible strategy.
The aim of the present study was to investigate the effect of conjugating
a series of well-known CPPs to the biologically active part of parathyroid
hormone, i.e., PTH(1–34), and to evaluate the effect with regard
to secondary structure, potency in Saos-2 cells, immunogenicity, safety,
as well as the transepithelial permeation across monolayers by using
the Caco-2 cell culture model. Further, co-administration of CPP and
PTHÂ(1–34) as an alternative to covalent conjugation was compared
with regard to the transepithelial permeation. CPP-conjugated PTH(1–34)
fusion peptides were successfully expressed in Escherichia
coli and purified from inclusion bodies. No clear
correlation between the degree of secondary structure of the CPP-conjugated
PTH(1–34) fusion peptides and their potency was found, albeit
a general decrease in permeation was observed for both N- and C-terminally
CPP-conjugated PTH(1–34) as compared to native PTH(1–34).
However, attachment of CPP to the N-terminus significantly increased
permeation across Caco-2 cell monolayers as compared to the corresponding
C-terminally CPP-conjugated PTH(1–34). In addition, the nonaarginine
sequence proved to be the only CPP capable of increasing permeation
when conjugated to PTH(1–34) as compared to co-administration
of CPP and PTH(1–34). This enhancement effect was, however,
associated with an unacceptably low level of cell viability. In conclusion,
covalent conjugation of CPPs to PTH(1–34) influenced the secondary
structure, potency, and transepithelial permeation efficiency of the
resulting conjugate, and hence this approach appears not to be favorable
as compared to co-administration when optimizing CPP-mediated permeation
of PTH(1–34) across an intestinal epithelium