A germline mutation abolishing the original stop codon of the human adenine phosphoribosyltransferase (APRT) gene leads to complete loss of the enzyme protein

1998 ◽  
Vol 102 (2) ◽  
pp. 197-202 ◽  
Author(s):  
Atsuo Taniguchi ◽  
Masayuki Hakoda ◽  
Hisashi Yamanaka ◽  
Chihiro Terai ◽  
Keiji Hikiji ◽  
...  
Keyword(s):  
Germline Mutation ◽  
Stop Codon ◽  
Complete Loss ◽  
Enzyme Protein ◽  
Adenine Phosphoribosyltransferase ◽  
Aprt Gene

Homology dependence of targeted recombination at the Chinese hamster APRT locus

1994 ◽  
Vol 14 (10) ◽  
pp. 6663-6673
Author(s):  
J B Scheerer ◽  
G M Adair
Keyword(s):  
Homologous Recombination ◽  
Sequence Homology ◽  
Chinese Hamster Ovary ◽  
Target Gene ◽  
Gene Deletion ◽  
Chinese Hamster ◽  
Adenine Phosphoribosyltransferase ◽  
Aprt Gene ◽  
Logarithmic Relationship ◽  
Targeted Recombination

Using simple linear fragments of the Chinese hamster adenine phosphoribosyltransferase (APRT) gene as targeting vectors, we have investigated the homology dependence of targeted recombination at the endogenous APRT locus in Chinese hamster ovary (CHO) cells. We have examined the effects of varying either the overall length of targeting sequence homology or the length of 5' or 3' flanking homology on both the frequency of targeted homologous recombination and the types of recombination events that are obtained. We find an exponential (logarithmic) relationship between length of APRT targeting homology and the frequency of targeted recombination at the CHO APRT locus, with the frequency of targeted recombination dependent upon both the overall length of targeting homology and the length of homology flanking each side of the target gene deletion. Although most of the APRT+ recombinants analyzed reflect simple targeted replacement or conversion of the target gene deletion, a significant fraction appear to have arisen by target gene-templated extension and correction of the targeting fragment sequences. APRT fragments with limited targeting homology flanking one side of the target gene deletion yield proportionately fewer target gene conversion events and proportionately more templated extension and vector correction events than do fragments with more substantial flanking homology.

scholarly journals Homology dependence of targeted recombination at the Chinese hamster APRT locus.

1994 ◽  
Vol 14 (10) ◽  
pp. 6663-6673 ◽  
Author(s):  
J B Scheerer ◽  
G M Adair
Keyword(s):  
Homologous Recombination ◽  
Sequence Homology ◽  
Chinese Hamster Ovary ◽  
Target Gene ◽  
Gene Deletion ◽  
Chinese Hamster ◽  
Adenine Phosphoribosyltransferase ◽  
Aprt Gene ◽  
Logarithmic Relationship ◽  
Targeted Recombination

Using simple linear fragments of the Chinese hamster adenine phosphoribosyltransferase (APRT) gene as targeting vectors, we have investigated the homology dependence of targeted recombination at the endogenous APRT locus in Chinese hamster ovary (CHO) cells. We have examined the effects of varying either the overall length of targeting sequence homology or the length of 5' or 3' flanking homology on both the frequency of targeted homologous recombination and the types of recombination events that are obtained. We find an exponential (logarithmic) relationship between length of APRT targeting homology and the frequency of targeted recombination at the CHO APRT locus, with the frequency of targeted recombination dependent upon both the overall length of targeting homology and the length of homology flanking each side of the target gene deletion. Although most of the APRT+ recombinants analyzed reflect simple targeted replacement or conversion of the target gene deletion, a significant fraction appear to have arisen by target gene-templated extension and correction of the targeting fragment sequences. APRT fragments with limited targeting homology flanking one side of the target gene deletion yield proportionately fewer target gene conversion events and proportionately more templated extension and vector correction events than do fragments with more substantial flanking homology.

scholarly journals Effects of nonsense mutations on nuclear and cytoplasmic adenine phosphoribosyltransferase RNA.

1996 ◽  
Vol 16 (8) ◽  
pp. 4426-4435 ◽  
Author(s):  
O Kessler ◽  
L A Chasin
Keyword(s):  
Steady State ◽  
Actinomycin D ◽  
Chinese Hamster ◽  
Nuclear Pore ◽  
Mrna Levels ◽  
Wild Type ◽  
Adenine Phosphoribosyltransferase ◽  
Aprt Gene ◽  
Steady State Levels ◽  
Nonsense Codons

We have analyzed Chinese hamster ovary (CHO) cell mutants bearing nonsense codons in four of the five exons of the adenine phosphoribosyltransferase (aprt) gene and have found a pattern of mRNA reduction similar to that seen in systems studied previously: a decrease in steady-state mRNA levels of 5- to 10-fold for mutations in exons 1, 2, and 4 but little effect for mutations in the 3'-most exon (exon 5). Nuclear aprt mRNA levels showed a similar decrease. Nonsense-containing aprt mRNA decayed at the same rate as wild-type mRNA in these cell lines after inhibition of transcription with actinomycin D. Nonsense-containing aprt mRNA is associated with polysomes, ruling out a model in which stable residual mRNA escapes degradation by avoiding translation initiation. A tetracycline-responsive form of the aprt gene was used to compare the stability of nonsense-containing and wild-type aprt mRNAs without globally inhibiting transcription. In contrast to measurements made in the presence of actinomycin D, after inhibition of aprt transcription with tetracycline, a nonsense-mediated destabilization of aprt mRNA was indeed demonstrable. The increased rate of decay of cytoplasmic aprt mRNA seen here could account for the nonsense-mediated reduction in steady-state levels of aprt mRNA. However, the low levels of nonsense-bearing aprt mRNA in the nucleus suggest a sensibility of mRNA to translation or translatability before it exits that compartment. Quantitation of the steady-state levels of transcripts containing introns revealed no accumulation of partially spliced aprt RNA and hence no indication of nonsense-mediated aberrancies in splicing. Our results are consistent with a model in which translation facilitates the export of mRNA through a nuclear pore. However, the mechanism of this intriguing nucleocytoplasmic communication remains to be determined.

An Unusual Course of a 2,8-Dihydroxyadeninuria Crystalline Nephropathy Secondary to Adenine Phosphoribosyltransferase Deficiency

Nephron ◽  
2021 ◽  
pp. 1-5
Author(s):  
Nicole Nourié ◽  
Hussein Nassereddine ◽  
Hiba Azar
Keyword(s):  
Genetic Disease ◽  
Autosomal Recessive ◽  
Middle Eastern ◽  
Disease Recurrence ◽  
Gene Variant ◽  
Adenine Phosphoribosyltransferase ◽  
Aprt Gene ◽  
Appropriate Therapy ◽  
Late Stages ◽  
Aprt Deficiency

Adenine phosphoribosyltransferase (APRT) deficiency is a rare disorder caused by an autosomal recessive genetic disease leading to the deposition of 2,8-dihydroxyadenine (2,8-DHA) in the kidney. The disease remains under-recognized, oftentimes diagnosed in late stages of renal insufficiency or a failed kidney allograft with biopsy-proven disease recurrence. Here, we present the case of a 59-year-old middle eastern male patient diagnosed with 2,8-DHA nephropathy after a very unusual presentation, and we show how the initiation of an appropriate therapy slowed down his evolution toward kidney replacement therapies. His disease was found to be secondary to a specific APRT gene variant c.188G>A p (Gly63Asp) also described in 4 other patients, all from middle eastern origins.

scholarly journals Mammalian ALKBH8 Possesses tRNA Methyltransferase Activity Required for the Biogenesis of Multiple Wobble Uridine Modifications Implicated in Translational Decoding

2010 ◽  
Vol 30 (7) ◽  
pp. 1814-1827 ◽  
Author(s):  
Lene Songe-Møller ◽  
Erwin van den Born ◽  
Vibeke Leihne ◽  
Cathrine B. Vågbø ◽  
Terese Kristoffersen ◽  
...  
Keyword(s):  
Stop Codon ◽  
Complete Loss ◽  
Accessory Protein ◽  
Methyltransferase Activity ◽  
Wobble Position ◽  
Trna Methyltransferase ◽  
Codon Reading

ABSTRACT Uridines in the wobble position of tRNA are almost invariably modified. Modifications can increase the efficiency of codon reading, but they also prevent mistranslation by limiting wobbling. In mammals, several tRNAs have 5-methoxycarbonylmethyluridine (mcm5U) or derivatives thereof in the wobble position. Through analysis of tRNA from Alkbh8 −/− mice, we show here that ALKBH8 is a tRNA methyltransferase required for the final step in the biogenesis of mcm5U. We also demonstrate that the interaction of ALKBH8 with a small accessory protein, TRM112, is required to form a functional tRNA methyltransferase. Furthermore, prior ALKBH8-mediated methylation is a prerequisite for the thiolation and 2′-O-ribose methylation that form 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U) and 5-methoxycarbonylmethyl-2′-O-methyluridine (mcm5Um), respectively. Despite the complete loss of all of these uridine modifications, Alkbh8 −/− mice appear normal. However, the selenocysteine-specific tRNA (tRNASec) is aberrantly modified in the Alkbh8 −/− mice, and for the selenoprotein Gpx1, we indeed observed reduced recoding of the UGA stop codon to selenocysteine.

A New Germline Stop Codon Mutation in Exon 15 of the APC Gene Predisposing to Familial Adenomatous Polyposis

2013 ◽  
Vol 28 (4) ◽  
pp. 405-408 ◽  
Author(s):  
Laura Schirosi ◽  
Marcello Pellegrino ◽  
Paolo Tarantino ◽  
Salvatore Mauro ◽  
Andrea Tinelli ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Familial Adenomatous Polyposis ◽  
Germline Mutation ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Colorectal Tumor ◽  
Apc Gene ◽  
Sequencing Analysis ◽  
Adenomatous Polyposis ◽  
Truncated Protein

Familial adenomatous polyposis (FAP) is an autosomal dominant disorder related to germline mutations of the adenomatous polyposis coli ( APC) gene. It is characterized by the detection of numerous adenomatous polyps that, if untreated, develop into colorectal cancer. We studied an Italian family with FAP history and the related colorectal tumor sample of the proband. Sequencing analysis of blood samples revealed the presence of a never-reported germline mutation in the APC gene (exon 15): an heterozygous G deletion at position c.2126 resulting in a premature stop codon (p.Gly721GlufsX6) and in a truncated protein. This mutation was also identified in the colorectal tumor tissue, together with a second known pathogenic heterozygotic somatic mutation, c.4348C>T (p.Arg1450X), which generates a premature truncated protein. The novel identified germline mutation is therefore related to FAP and, in accordance with Knudson's “two hit” hypothesis, can be considered the first event predisposing to the insurgence of colorectal cancer in these patients. The somatic hit inactivating the second allele of the APC gene is located in the mutation cluster region of the gene; this is not a random event since it depends on the position of the germline mutation. The inactivation of APC generates the neoplastic growth advantage to the cell.

scholarly journals Identification of lysine at the active site of human 5-aminolaevulinate dehydratase

1986 ◽  
Vol 236 (2) ◽  
pp. 447-451 ◽  
Author(s):  
P N B Gibbs ◽  
P M Jordan
Keyword(s):  
Catalytic Activity ◽  
Amino Acid ◽  
Acid Hydrolysis ◽  
Active Site ◽  
Complete Loss ◽  
Enzyme Protein ◽  
Aminolaevulinic Acid ◽  
Cnbr Cleavage

Reduction of human 5-aminolaevulinate dehydratase with NaBH4 in the presence of 14C-labelled substrate led to complete loss of catalytic activity and to incorporation of label into the enzyme protein. By comparison with authentic lysyl-aminolaevulinic acid, prepared chemically, the modified active-site amino acid obtained by acid hydrolysis was shown to be lysine. Sequencing of a CNBr-cleavage peptide isolated from the inactivated 14C-labelled enzyme revealed that the lysine was present within the sequence M-V-K-P-G-M.

Investigating the functional link between TMEM165 and SPCA1

2019 ◽  
Vol 476 (21) ◽  
pp. 3281-3293 ◽  
Author(s):  
Elodie Lebredonchel ◽  
Marine Houdou ◽  
Hans-Heinrich Hoffmann ◽  
Kateryna Kondratska ◽  
Marie-Ange Krzewinski ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Complete Loss ◽  
Protein Family ◽  
Uncharacterized Protein ◽  
Functional Link ◽  
P Type

TMEM165 was highlighted in 2012 as the first member of the Uncharacterized Protein Family 0016 (UPF0016) related to human glycosylation diseases. Defects in TMEM165 are associated with strong Golgi glycosylation abnormalities. Our previous work has shown that TMEM165 rapidly degrades with supraphysiological manganese supplementation. In this paper, we establish a functional link between TMEM165 and SPCA1, the Golgi Ca2+/Mn2+ P-type ATPase pump. A nearly complete loss of TMEM165 was observed in SPCA1-deficient Hap1 cells. We demonstrate that TMEM165 was constitutively degraded in lysosomes in the absence of SPCA1. Complementation studies showed that TMEM165 abundance was directly dependent on SPCA1's function and more specifically its capacity to pump Mn2+ from the cytosol into the Golgi lumen. Among SPCA1 mutants that differentially impair Mn2+ and Ca2+ transport, only the Q747A mutant that favors Mn2+ pumping rescues the abundance and Golgi subcellular localization of TMEM165. Interestingly, the overexpression of SERCA2b also rescues the expression of TMEM165. Finally, this paper highlights that TMEM165 expression is linked to the function of SPCA1.

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