Prohormone convertases 1/3 and 2 together orchestrate the site-specific cleavages of progastrin to release gastrin-34 and gastrin-17

Cellular synthesis of peptide hormones requires PCs (prohormone convertases) for the endoproteolysis of prohormones. Antral G-cells synthesize the most gastrin and express PC1/3, 2 and 5/6 in the rat and human. But the cleavage sites in progastrin for each PC have not been determined. Therefore, in the present study, we measured the concentrations of progastrin, processing intermediates and α-amidated gastrins in antral extracts from PC1/3-null mice and compared the results with those in mice lacking PC2 and wild-type controls. The expression of PCs was examined by immunocytochemistry and in situ hybridization of mouse G-cells. Finally, the in vitro effect of recombinant PC5/6 on progastrin and progastrin fragments containing the relevant dibasic cleavage sites was also examined. The results showed that mouse G-cells express PC1/3, 2 and 5/6. The concentration of progastrin in PC1/3-null mice was elevated 3-fold. Chromatography showed that cleavage of the Arg36Arg37 and Arg73Arg74 sites were grossly decreased. Accordingly, the concentrations of progastrin products were markedly reduced, α-amidated gastrins (-34 and -17) being 25% of normal. Lack of PC1/3 was without effect on the third dibasic site (Lys53Lys54), which is the only processing site for PC2. Recombinant PC5/6 did not cleave any of the dibasic processing sites in progastrin and fragments containing the relevant dibasic processing sites. The complementary cleavages of PC1/3 and 2, however, suffice to explain most of the normal endoproteolysis of progastrin. Moreover, the results show that PCs react differently to the same dibasic sequences, suggesting that additional structural factors modulate the substrate specificity.

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A Point Mutation in the mma3 Gene Is Responsible for Impaired Methoxymycolic Acid Production in Mycobacterium bovis BCG Strains Obtained after 1927

Journal of Bacteriology ◽

10.1128/jb.182.12.3394-3399.2000 ◽

2000 ◽

Vol 182 (12) ◽

pp. 3394-3399 ◽

Cited By ~ 59

Author(s):

Marcel A. Behr ◽

Benjamin G. Schroeder ◽

Jacquelyn N. Brinkman ◽

Richard A. Slayden ◽

Clifton E. Barry

Keyword(s):

Point Mutation ◽

Mycobacterium Bovis ◽

Mycobacterium Smegmatis ◽

Pasteur Institute ◽

Wild Type ◽

Phenotypic Properties ◽

Site Specific ◽

Mutant Population ◽

Mycolic Acids

ABSTRACT BCG vaccines are substrains of Mycobacterium bovisderived by attenuation in vitro. After the original attenuation (1908 to 1921), BCG strains were maintained by serial propagation in different BCG laboratories (1921 to 1961). As a result, various BCG substrains developed which are now known to differ in a number of genetic and phenotypic properties. However, to date, none of these differences has permitted a direct phenotype-genotype link. Since BCG strains differ in their abilities to synthesize methoxymycolic acids and since recent work has shown that the mma3 gene is responsible for O-methylation of hydroxymycolate precursors to form methoxymycolic acids, we analyzed methoxymycolate production andmma3 gene sequences for a genetically defined collection of BCG strains. We found that BCG strains obtained from the Pasteur Institute in 1927 and earlier produced methoxymycolates in vitro but that those obtained from the Pasteur Institute in 1931 and later all failed to synthesize methoxymycolates, and furthermore, themma3 sequence of the latter strains differs from that ofMycobacterium tuberculosis H37Rv by a point mutation at bp 293. Site-specific introduction of this guanine-to-adenine mutation into wild-type mma3 (resulting in the replacement of glycine 98 with aspartic acid) eliminated the ability of this enzyme to produce O-methylated mycolic acids when the mutant was cloned in tandem with mma4 into Mycobacterium smegmatis. These findings indicate that a point mutation in mma3 occurred between 1927 and 1931, and that this mutant population became the dominant clone of BCG at the Pasteur Institute.

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Developmental aspects of adipose tissue in GH receptor and prolactin receptor gene disrupted mice: site-specific effects upon proliferation, differentiation and hormone sensitivity

Journal of Endocrinology ◽

10.1677/joe.1.06939 ◽

2006 ◽

Vol 191 (1) ◽

pp. 101-111 ◽

Cited By ~ 39

Author(s):

David J Flint ◽

Nadine Binart ◽

Stephanie Boumard ◽

John J Kopchick ◽

Paul Kelly

Keyword(s):

Adipose Tissue ◽

Receptor Gene ◽

Metabolic Effects ◽

Wild Type ◽

Extrinsic Factors ◽

Differentiation Potential ◽

Site Specific ◽

Proliferation And Differentiation

Direct metabolic effects of GH on adipose tissue are well established, but effects of prolactin (PRL) have been more controversial. Recent studies have demonstrated PRL receptors on adipocytes and effects of PRL on adipose tissue in vitro. The role of GH in adipocyte proliferation and differentiation is also controversial, since GH stimulates adipocyte differentiation in cell lines, whereas it stimulates proliferation but inhibits differentiation of adipocytes in primary cell culture. Using female gene disrupted (ko) mice, we showed that absence of PRL receptors (PRLRko) impaired development of both internal and s.c. adipose tissue, due to reduced numbers of adipocytes, an effect differing from that of reduced food intake, where cell volume is decreased. In contrast, GHRko mice exhibited major decreases in the number of internal adipocytes, whereas s.c. adipocyte numbers were increased, even though body weight was decreased by 40–50%. The changes in adipose tissue in PRLRko mice appeared to be entirely due to extrinsic factors since preadipocytes proliferated and differentiated in similar fashion to wild-type animals in vitro and their response to insulin and isoproterenol was similar to wild-type animals. This contrasted with GHRko mice, where s.c. adipocytes proliferated, differentiated, and responded to hormones in identical fashion to controls, whereas parametrial adipocytes exhibited markedly depressed proliferation and differentiation potential and failed to respond to insulin or noradrenaline. Our results provide in vivo evidence that both GH and PRL stimulate differentiation of adipocytes but that the effects of GH are site specific and induce intrinsic changes in the precursor population, which are retained in vitro.

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Identification of prolyl carboxypeptidase as an alternative enzyme for processing of renal angiotensin II using mass spectrometry

AJP Cell Physiology ◽

10.1152/ajpcell.00346.2012 ◽

2013 ◽

Vol 304 (10) ◽

pp. C945-C953 ◽

Cited By ~ 28

Author(s):

Nadja Grobe ◽

Nathan M. Weir ◽

Orly Leiva ◽

Frank S. Ong ◽

Kenneth E. Bernstein ◽

...

Keyword(s):

Ph Control ◽

Mass Spectrometric ◽

Acidic Ph ◽

Ang Ii ◽

Converting Enzyme ◽

Wild Type ◽

Angiotensin Converting Enzyme 2 ◽

Genetic Mouse Models

Angiotensin-converting enzyme 2 (ACE2) catalyzes conversion of ANG II to ANG-(1–7). The present study uses newly established proteomic approaches and genetic mouse models to examine the contribution of alternative renal peptidases to ACE2-independent formation of ANG-(1–7). In situ and in vitro mass spectrometric characterization showed that substrate concentration and pH control renal ANG II processing. At pH ≥6, ANG-(1–7) formation was significantly reduced in ACE2 knockout (KO) mice. However, at pH <6, formation of ANG-(1–7) in ACE2 KO mice was similar to that in wild-type (WT) mice, suggesting alternative peptidases for renal ANG II processing. Furthermore, the dual prolyl carboxypeptidase (PCP)-prolyl endopeptidase (PEP) inhibitor Z-prolyl-prolinal reduced ANG-(1–7) formation in ACE2 KO mice, while the ACE2 inhibitor MLN-4760 had no effect. Unlike the ACE2 KO mice, ANG-(1–7) formation from ANG II in PEP KO mice was not different from that in WT mice at any tested pH. However, at pH 5, this reaction was significantly reduced in kidneys and urine of PCP-depleted mice. In conclusion, results suggest that ACE2 metabolizes ANG II in the kidney at neutral and basic pH, while PCP catalyzes the same reaction at acidic pH. This is the first report demonstrating that renal ANG-(1–7) formation from ANG II is independent of ACE2. Elucidation of ACE2-independent ANG-(1–7) production pathways may have clinically important implications in patients with metabolic and renal disease.

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STUDIES ON THE RIGOR RESULTING FROM THE THAWING OF FROZEN FROG SARTORIUS MUSCLE

The Journal of General Physiology ◽

10.1085/jgp.33.5.563 ◽

1950 ◽

Vol 33 (5) ◽

pp. 563-577 ◽

Cited By ~ 34

Author(s):

S. V. Perry

Keyword(s):

Hydrogen Peroxide ◽

Iodoacetic Acid ◽

Sartorius Muscle ◽

Fixed Length ◽

Frog Sartorius Muscle ◽

Vitro Effect ◽

Resting Muscle ◽

Frog Sartorius

1. The rigor which takes place when completely frozen frog sartorius muscle is thawed ("thaw rigor"), is accompanied by a decrease in length of 70 per cent and a loss in weight of 35 per cent, whether the muscle is frozen in the resting or the exhausted condition, or during isometric tetanus. Muscle tetanized to maximal shortening shows a loss in weight of 25 per cent on thawing. 2. A load of 8 gm. is sufficient to prevent the decrease in length on thawing, but after its removal the muscle will shorten almost to the normal extent. 3. Inhibitors such as azide, cyanide, 2:4 dinitrophenol, p-chloromercuribenzoate, Cu, and hydrogen peroxide, when used for periods not exceeding 1 hour, have little effect on the shortening; although in some cases these poisons render the muscle inexcitable. 4. Muscles poisoned with iodoacetic acid and stimulated to exhaustion, or maintained at fixed length in nitrogen, show little or no shortening on thawing. ATP can produce shortening in the muscles in which it has been prevented. 5. The phenomenon is considered to be due to an in situ synaeresis of the actomyosin of the myofibrils. As a result of the disorganisation of the muscle protoplasm produced by the freezing and subsequent thawing, the ATP, which must be bound or localized in the resting muscle, can act on the myofibril in a similar manner to its in vitro effect on the actomyosin thread.

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Conserved C-Terminal Threonine of Hepatitis C Virus NS3 Regulates Autoproteolysis and Prevents Product Inhibition

Journal of Virology ◽

10.1128/jvi.78.2.700-709.2004 ◽

2004 ◽

Vol 78 (2) ◽

pp. 700-709 ◽

Cited By ~ 15

Author(s):

Wenyan Wang ◽

Frederick C. Lahser ◽

MinKyung Yi ◽

Jacquelyn Wright-Minogue ◽

Ellen Xia ◽

...

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

In Vitro Transcription ◽

Product Inhibition ◽

Cleavage Sites ◽

Wild Type ◽

Genome Sequences ◽

Mutant Proteins ◽

C Terminus

ABSTRACT Inspection of over 250 hepatitis C virus (HCV) genome sequences shows that a threonine is strictly conserved at the P1 position in the NS3-NS4A (NS3-4A) autoproteolysis junction, while a cysteine is maintained as the P1 residue in all of the putative trans cleavage sites (NS4A-4B, NS4B-5A, and NS5A-5B). To understand why T631 is conserved at the NS3-4A junction of HCV, a series of in vitro transcription-translation studies were carried out using wild-type and mutant (T631C) NS3-4A constructs bearing native, truncated, and mutant NS4A segments. The autocleavage of the wild-type junction was found to be dependent on the presence of the central cofactor domain of NS4A (residues 21 to 34). In contrast, all NS3-4A T631C mutant proteins underwent self-cleavage even in the absence of the cofactor. Subgenomic replicons derived from the Con1 strain of HCV and bearing the T631C mutation showed reduced levels of colony formation in transfection studies. Similarly, replicons derived from a second genotype 1b virus, HCV-N, demonstrated a comparable reduction in replication efficiency in transient-transfection assays. These data suggest that the threonine is conserved at position 631 because it serves two functions: (i) to slow processing at the NS3-4A cleavage site, ensuring proper intercalation of the NS4A cofactor with NS3 prior to polyprotein scission, and (ii) to prevent subsequent product inhibition by the NS3 C terminus.

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Cardiomyocyte differentiation by GATA-4-deficient embryonic stem cells

Development ◽

10.1242/dev.124.19.3755 ◽

1997 ◽

Vol 124 (19) ◽

pp. 3755-3764 ◽

Cited By ~ 4

Author(s):

N. Narita ◽

M. Bielinska ◽

D.B. Wilson

Keyword(s):

Transcription Factor ◽

In Situ Hybridization ◽

Es Cells ◽

Embryonic Stem ◽

Embryoid Bodies ◽

Cardiomyocyte Differentiation ◽

Wild Type ◽

Cell Stage

In situ hybridization studies, promoter analyses and antisense RNA experiments have implicated transcription factor GATA-4 in the regulation of cardiomyocyte differentiation. In this study, we utilized Gata4−/− embryonic stem (ES) cells to determine whether this transcription factor is essential for cardiomyocyte lineage commitment. First, we assessed the ability of Gata4−/− ES cells form cardiomyocytes during in vitro differentiation of embryoid bodies. Contracting cardiomyocytes were seen in both wild-type and Gata4−/− embryoid bodies, although cardiomyocytes were observed more often in wild type than in mutant embryoid bodies. Electron microscopy of cardiomyocytes in the Gata4−/− embryoid bodies revealed the presence of sarcomeres and junctional complexes, while immunofluorescence confirmed the presence of cardiac myosin. To assess the capacity of Gata4−/− ES cells to differentiate into cardiomyocytes in vivo, we prepared and analyzed chimeric mice. Gata4−/− ES cells were injected into 8-cell-stage embryos derived from ROSA26 mice, a transgenic line that expresses beta-galactosidase in all cell types. Chimeric embryos were stained with X-gal to discriminate ES cell- and host-derived tissue. Gata4−/− ES cells contributed to endocardium, myocardium and epicardium. In situ hybridization showed that myocardium derived from Gata4−/− ES cells expressed several cardiac-specific transcripts, including cardiac alpha-myosin heavy chain, troponin C, myosin light chain-2v, Nkx-2.5/Csx, dHAND, eHAND and GATA-6. Taken together these results indicate that GATA-4 is not essential for terminal differentiation of cardiomyocytes and suggest that additional GATA-binding proteins known to be in cardiac tissue, such as GATA-5 or GATA-6, may compensate for a lack of GATA-4.

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Interaction of BAG1 and Hsp70 Mediates Neuroprotectivity and Increases Chaperone Activity

Molecular and Cellular Biology ◽

10.1128/mcb.25.9.3715-3725.2005 ◽

2005 ◽

Vol 25 (9) ◽

pp. 3715-3725 ◽

Cited By ~ 37

Author(s):

Jan Liman ◽

Sundar Ganesan ◽

Christoph P. Dohm ◽

Stan Krajewski ◽

John C. Reed ◽

...

Keyword(s):

Neuronal Differentiation ◽

Heat Shock Protein 70 ◽

Fluorescent Protein ◽

Yellow Fluorescent Protein ◽

Full Length ◽

Wild Type ◽

Binding Characteristics ◽

In Cells

ABSTRACT It was recently shown that Bcl-2-associated athanogene 1 (BAG1) is a potent neuroprotectant as well as a marker of neuronal differentiation. Since there appears to exist an equilibrium within the cell between BAG1 binding to heat shock protein 70 (Hsp70) and BAG1 binding to Raf-1 kinase, we hypothesized that changing BAG1 binding characteristics might significantly alter BAG1 function. To this end, we compared rat CSM14.1 cells and human SHSY-5Y cells stably overexpressing full-length BAG1 or a deletion mutant (BAGΔC) no longer capable of binding to Hsp70. Using a novel yellow fluorescent protein-based foldase biosensor, we demonstrated an upregulation of chaperone in situ activity in cells overexpressing full-length BAG1 but not in cells overexpressing BAGΔC compared to wild-type cells. Interestingly, in contrast to the nuclear and cytosolic localizations of full-length BAG1, BAGΔC was expressed exclusively in the cytosol. Furthermore, cells expressing BAGΔC were no longer protected against cell death. However, they still showed accelerated neuronal differentiation. Together, these results suggest that BAG1-induced activation of Hsp70 is important for neuroprotectivity, while BAG1-dependent modulation of neuronal differentiation in vitro is not.

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Mutations within the propeptide, the primary cleavage site or the catalytic site, or deletion of C-terminal sequences, prevents secretion of proPC2 from transfected COS-7 cells

Biochemical Journal ◽

10.1042/bj3210367 ◽

1997 ◽

Vol 321 (2) ◽

pp. 367-373 ◽

Cited By ~ 23

Author(s):

Neil A. TAYLOR ◽

Kathleen I. J. SHENNAN ◽

Daniel F. CUTLER ◽

Kevin DOCHERTY

Keyword(s):

Endoplasmic Reticulum ◽

Secretory Pathway ◽

Catalytic Triad ◽

Cleavage Sites ◽

Wild Type ◽

Structural Requirements ◽

Processing Site ◽

P Domain ◽

Primary Cleavage ◽

Secretory Apparatus

PC2 is a neuroendocrine endoprotease involved in the processing of prohormones and proneuropeptides. PC2 is synthesized as a proenzyme which undergoes proteolytic maturation within the cellular secretory apparatus. Cleavage occurs at specific sites to remove the N-terminal propeptide. The aim of the present study was to investigate structural requirements for the transfer of proPC2 through the secretory pathway. A series of mutant proPC2 constructs were transfected into COS-7 cells and the fate of the expressed proteins followed by pulseŐchase analysis and immunocytochemistry. Human PC2 was secreted relatively slowly, and appeared in the medium primarily as proPC2 (75 kDa), together with much lower amounts of a processed intermediate (71 kDa) and mature PC2 (68 kDa). Mutations within the primary processing site or the catalytic triad caused the protein to accumulate intracellularly, whereas deletion of part of the propeptide, the P-domain or the C-terminal regions also prevented secretion. Immunocytochemistry showed that wild-type hPC2 was localized mainly in the Golgi, whereas two representative mutants showed a distribution typical of proteins resident in the endoplasmic reticulum. The results suggest that proenzyme processing is not essential for secretion of PC2, but peptides containing mutations that affect the ability of the propeptide (and cleavage sites) to fold within the catalytic pocket are not transferred beyond the early stages of the secretory pathway. C-terminal sequences may be involved in stabilizing such conformations.

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