Immunohistochemical Localization of Carboxypeptidases E and D in the Human Placenta and Umbilical Cord

Reznik, Sandra E.; Salafia, Carolyn M.; Lage, Janice M.; Fricker, Lloyd D.

doi:10.1177/002215549804601204

Cited by 22 publications

(16 citation statements)

References 40 publications

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“…We have demonstrated that pro-IGF-II is processed at two separate sites: RLRR 104 2 and KSER 68 2 to generate IGF-II (1-104) and IGF-II (1-68), respectively. Exposed basic residues at the carboxyl terminal are further cleaved by carboxypeptidases E and D (26), which are widely distributed in the placenta (27). Therefore, Arg-68 is further cleaved from IGF-II (1-68) to generate a peptide containing 67 amino acids, the mature IGF-II (1-67) form.…”

Section: Discussionmentioning

confidence: 99%

Role of pro-IGF-II processing by proprotein convertase 4 in human placental development

Qiu

Basak

Mbikay

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Fetal growth restriction (intrauterine growth restriction, IUGR) is a leading cause of perinatal mortality. However, the causes of aberrant development of the placenta and, thus, of the fetus, are not currently known. Insulin-like growth factor II (IGF-II) has been shown to be an important regulator of fetoplacental growth. This growth factor must undergo posttranslational processing, and, thus, we hypothesized that aberrant processing of pro-IGF-II to IGF-II may be a cause of IUGR. Here, we have found that the proprotein convertase PC4 is expressed in the human placenta and that it cleaves pro-IGF-II to generate the intermediate processed form, IGF-II (1-102) and, subsequently, mature IGF-II (1-67), which are accounted for by the removal of terminal basic residues by carboxypeptidases. This processing confers the ability of IGF-II to activate invasive trophoblast cells through AKT phosphorylation, whereas inhibition of PC4 by a PC4-specific inhibitor blocks pro-IGF-II processing and reduces trophoblast cell migration, which can be partly restored by addition of mature IGF-II. Consistent with the hypothesis that IGF-II processing is implicated in IUGR, sera of patients carrying IUGR fetuses displayed elevated levels of pro-IGF-II. Thus, abnormal processing of IGF-II by PC4 may represent a previously uncharacterized mechanism involved in the pathophysiology of fetoplacental growth restriction, and elevated pro-IGF-II may be a useful clinical marker for risk of IUGR.insulin-like growth factor II ͉ intrauterine growth restriction

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Section: Discussionmentioning

confidence: 99%

Role of pro-IGF-II processing by proprotein convertase 4 in human placental development

Qiu

Basak

Mbikay

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…Several carboxypeptidases have been described in vascular SMC, where they function to either activate or inactivate proteins involved with vasomotion or growth (32)(33)(34)). An aortic carboxypeptidase-like protein was shown to be up-regulated during vascular SMC differentiation in vitro (35).…”

Section: Discussionmentioning

confidence: 99%

Cloning of a Novel Retinoid-inducible Serine Carboxypeptidase from Vascular Smooth Muscle Cells

Chen

Streb²,

Maltby

et al. 2001

Journal of Biological Chemistry

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Retinoids block smooth muscle cell (SMC) proliferation and attenuate neointimal formation after vascular injury, presumably through retinoid receptor-mediated changes in gene expression. To identify target genes in SMC whose encoded proteins could contribute to such favorable biological effects, we performed a subtractive screen for retinoid-inducible genes in cultured SMC. Here, we report on the cloning and initial characterization of a novel retinoid-inducible serine carboxypeptidase (RISC). Expression of RISC is low in cultured SMC but progressively increases over a 5-day time-course treatment with all-trans-retinoic acid. A near full-length rat RISC cDNA was cloned and found to have a 452-amino acid open reading frame containing an aminoterminal signal sequence, followed by several conserved domains comprising the catalytic triad common to members of the serine carboxypeptidase family. In vitro transcription and translation experiments showed that the rat RISC cDNA generates a ϳ51-kDa protein. Confocal immunofluorescence microscopy of COS-7 cells transiently transfected with a RISC-His tag plasmid revealed cytosolic localization of the fusion protein.Western blotting studies using conditioned medium from transfected COS-7 cells suggest that RISC is a secreted protein. Tissue Northern blotting studies demonstrated robust expression of RISC in rat aorta, bladder, and kidney with much lower levels in all other tissues analyzed; high level RISC expression was also observed in human kidney. In situ hybridization verified the localization of RISC to medial SMC of the adult rat aorta. Interestingly, expression in kidney was restricted to proximal convoluted tubules; little or no expression was observed in glomerular cells, distal convoluted and collecting tubules, or medullary cells. Radiation hybrid mapping studies placed the rat RISC locus on chromosome 10q. These studies reveal a novel retinoid-inducible protease whose activity may be involved in vascular wall and kidney homeostasis.

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“…The cellular distribution of carboxypeptidase Z is restricted to specific cell types, such as the leptomeningeal cells in brain (36). In contrast, CPD has a broad tissue distribution and is present in many cell types in each tissue (37)(38)(39)(40). Also, CPD is present along with furin in the trans Golgi network and immature secretory vesicles (41,42).…”

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confidence: 99%

Characterization of the Enzymatic Properties of the First and Second Domains of Metallocarboxypeptidase D

Novikova

Eng

Lin

et al. 1999

Journal of Biological Chemistry

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Carboxypeptidase D (CPD) contains three domains with homology to other metallocarboxypeptidases. To further characterize the various domains, we constructed a series of point mutants with a critical active site Glu of duck CPD converted to Gln. The proteins were expressed in the baculovirus system, purified to homogeneity, and characterized. Point mutations within both the first and second domains eliminated enzyme activity, indicating that the third domain is inactive toward dansyl-Phe-Ala-Arg. CPD removed only the C-terminal Lys or Arg from peptides, with the first domain more efficient toward Arg and the second domain more efficient toward Lys. Peptides containing Pro in the penultimate position were poorly cleaved by either domain. Cleavage of a peptide with Ala in the penultimate position was most efficient, with the relative order Ala > Met > Ser, Phe > Tyr > Trp > Thr > Gln, Asp, Leu, Gly Ͼ Ͼ Ͼ Ͼ Pro for CPD with both domains active. There were only minor differences between the first and the second domains regarding the influence of the penultimate amino acid. The first domain was optimally active at pH 6.3-7.5, whereas the second domain was optimally active at pH 5.0 -6.5. Thus, the first and second carboxypeptidase domains have complementary enzyme activities. Furthermore, the finding that CPD with both domains active shows a broad activity to a wide range of substrates is consistent with a role for this enzyme in the processing of many proteins that transit the secretory pathway.

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Immunohistochemical Localization of Carboxypeptidases E and D in the Human Placenta and Umbilical Cord

Cited by 22 publications

References 40 publications

Role of pro-IGF-II processing by proprotein convertase 4 in human placental development

Role of pro-IGF-II processing by proprotein convertase 4 in human placental development

Cloning of a Novel Retinoid-inducible Serine Carboxypeptidase from Vascular Smooth Muscle Cells

Characterization of the Enzymatic Properties of the First and Second Domains of Metallocarboxypeptidase D

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