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Biomedical subjects

B Wieringa

Publications and source records attributed to B Wieringa.

At least 91 records · Page 5Linked to original sources
PubMed1994

Normal development, growth and reproduction in cellular retinoic acid binding protein-I (CRABPI) null mutant mice.

We have generated mouse null mutants for the cellular retinoic acid (RA) binding protein type I (CRABPI), a protein whose spatio-temporal expression pattern coincides with the target tissues for RA action. Inactivation of the CRABPI gene was accomplished via homologous recombination in embryonic stem cells. Cells carrying the correctly targeted gene were injected into blastocysts and the resulting chimaeras yielded offspring heterozygous for the knockout mutation. Subsequent breeding programs resulted in normal litter sizes containing viable and fertile CRABPI deficient mice. Homozygous mice carrying the knockout mutation were studied in detail to detect possible organ and skeletal anomalies and/or abnormalities of the hematopoietic system. No overt phenotype was evident indicating that a deficiency for CRABPI does not seem to interfere with normal development, growth and reproduction.

Animals↗
PubMed1994

The human gene for water channel aquaporin 1 (AQP1) is localized on chromosome 7p15-->p14.

The chromosomal localization of the gene encoding aquaporin 1 (previously called CHIP28), which acts as a water channel in erythrocytes and in the renal proximal tubules and descending limbs of Henle, was determined. Southern blot hybridizations on chromosomal DNA of a panel of 25 different human x rodent hybrid cell lines localized the aquaporin 1 gene to human chromosome 7. Additionally, in situ hybridization on R-banded metaphase chromosomes sublocalized the aquaporin 1 gene (AQP1) to 7p15-->p14, and some sequence-tagged sites in this region were identified.

Animals↗
PubMed1994

Assignment of the human gene for the water channel of renal collecting duct Aquaporin 2 (AQP2) to chromosome 12 region q12-->q13.

The chromosomal localization of the gene encoding Aquaporin 2 (previously called WCH-CD), which acts as a water channel in the collecting tubules of the kidney, was determined. Southern blot hybridizations of chromosomal DNA from a panel of 25 different human-rodent hybrid cell lines assigned AQP2 to the q-arm of human chromosome 12. Additionally, in situ hybridization on R-banded metaphase chromosomes localized AQP2 to the q12-->q13 region of this chromosome.

Aquaporin 2↗
PubMed1994

Gonosomal mosaicism in myotonic dystrophy patients: involvement of mitotic events in (CTG)n repeat variation and selection against extreme expansion in sperm.

Myotonic dystrophy (DM) is caused by abnormal expansion of a polymorphic (CTG)n repeat, located in the DM protein kinase gene. We determined the (CTG)n repeat lengths in a broad range of tissue DNAs from patients with mild, classical, or congenital manifestation of DM. Differences in the repeat length were seen in somatic tissues from single DM individuals and twins. Repeats appeared to expand to a similar extent in tissues originating from the same embryonal origin. In most male patients carrying intermediate- or small-sized expansions in blood, the repeat lengths covered a markedly wider range in sperm. In contrast, male patients with large allele expansions in blood (> 700 CTGs) had similar or smaller repeats in sperm, when detectable. Sperm alleles with > 1,000 CTGs were not seen. We conclude that DM patients can be considered gonosomal mosaics, i.e., combined somatic and germ-line tissue mosaics. Most remarkably, we observed multiple cases where the length distributions of intermediate- or small-sized alleles in fathers' sperm were significantly different from that in their offspring's blood. Our combined findings indicate that intergenerational length changes in the unstable CTG repeat are most likely to occur during early embryonic mitotic divisions in both somatic and germ-line tissue formation. Both the initial CTG length, the overall number of cell divisions involved in tissue formation, and perhaps a specific selection process in spermatogenesis may influence the dynamics of this process. A model explaining mitotic instability and sex-dependent segregation phenomena in DM manifestation is discussed.

Aged↗
PubMed1993

Skeletal muscles of mice deficient in muscle creatine kinase lack burst activity.

To understand the physiological role of the creatine kinase-phosphocreatine (CK-PCr) system in muscle bioenergetics, a null mutation of the muscle CK (M-CK) gene was introduced into the germline of mice. Mutant mice show no alterations in absolute muscle force, but lack the ability to perform burst activity. Their fast-twitch fibers have an increased intermyofibrillar mitochondrial volume and an increased glycogenolytic/glycolytic potential. PCr and ATP levels are normal in resting M-CK-deficient muscles, but rates of high energy phosphate exchange between PCr and ATP are at least 20-fold reduced. Strikingly, PCr levels decline normally during muscle exercise, suggesting that M-CK-mediated conversion is not the only route for PCr utilization in active muscle.

Adenosine Triphosphate↗
PubMed1993

SKALP/elafin: an elastase inhibitor from cultured human keratinocytes. Purification, cDNA sequence, and evidence for transglutaminase cross-linking.

SKALP/Elafin is a proteinase inhibitor found in psoriatic epidermis as a short polypeptide of 6 kDa. Here we present evidence that this protein is synthesized as a larger precursor molecule with distinct biological features. Purification and NH2-terminal sequencing of SKALP/elafin from cultured human keratinocytes and the cloning of its cDNA revealed the existence of a mature protein, which upon cleavage of a hydrophobic signal sequence of 22 amino acids has a calculated molecular mass of 9.9 kDa (95 amino acids). In addition to the known proteinase inhibitor domain, the mature protein contains a domain with 4 repeats which are homologous to putative transglutaminase substrate motifs. We were able to demonstrate on Western blots that immunoreactive SKALP is present in high molecular weight proteins extracted from psoriatic skin. This suggests that SKALP is covalently attached to epidermal proteins. In addition it was found that both the complete SKALP molecule and a synthetic peptide of the NH2-terminal portion of SKALP could be used as a transglutaminase substrate. We therefore speculate that SKALP/elafin, secreted by epidermal keratinocytes in inflamed skin, exists both as a free 6-kDa form and as an immobilized 9.9-kDa form covalently attached to the cornified envelopes by transglutaminase cross-linking.

Amino Acid Sequence↗
PubMed1993

No imprinting involved in the expression of DM-kinase mRNAs in mouse and human tissues.

To explain the restriction of early onset cases of myotonic dystrophy (DM) to maternal transmittance and the significant excess of male transmitters in the last asymptomatic generation, the involvement of parental effects on the autosomal dominant mode of inheritance has been suggested. Using FISH we confirmed that the DM-kinase gene is proximal to the ApoE gene on mouse chromosome 7, close to an imprinted segment. To study whether there is any firm molecular basis for the speculation that imprinting may be involved in DM we have analysed the expression of paternal and maternal alleles of the DM-kinase gene in human and mouse tissues. Length polymorphisms in the 3' non coding exons of human and mouse DM kinase genes, i.e. the variable [CTG]n repeat motif in humans and a newly identified Cn stretch variation in mice, served as tools to distinguish between allelic RNA products in various tissues. In human tissues, presence of transcripts from both parental alleles could be demonstrated by RT-PCR. In mouse, similar observations were made using a RNAse protection assay on fetal and adult muscle RNAs. We conclude that imprinting does not play a role in the expression of the DM kinase gene.

Abortion, Spontaneous↗
PubMed1993

Localization of the gamma-subunit of the skeletal muscle L-type voltage-dependent calcium channel gene (CACNLG) to human chromosome band 17q24 by in situ hybridization and identification of a polymorphic repetitive DNA sequence at the gene locus.

The skeletal muscle dihydropyridine receptor consists of five subunits and fulfils an essential role in excitation-contraction coupling. A genomic clone for the human gamma subunit was used to map the gene (CACNLG) to chromosome band 17q24 by in situ hybridization. Contained within the gene is a 416-bp polymorphic repetitive DNA element that is potentially useful as a genetic marker.

Amino Acid Sequence↗
PubMed1993

Influence of sex of the transmitting parent as well as of parental allele size on the CTG expansion in myotonic dystrophy (DM).

In patients with myotonic dystrophy (DM), the severity of clinical signs is correlated with the length of a (CTG)n trinucleotide repeat sequence. This sequence tends to expand in subsequent generations. In order to examine the kinetics of this process and, in particular, the influence of the mutant-allele size and the sex of the transmitting parent, we have studied (CTG)n repeat lengths in the offspring of 38 healthy carriers with small mutations (less than 100 CTG trinucleotides, mean length [CTG]67). In these studies, we found a weakly positive correlation between the size of the mutation in the carrier parents and that in their offspring. Furthermore, we observed that, in the offspring of male transmitters, repeat lengths exceeding 100 CTG trinucleotides were much more frequent than in the offspring of carrier females (48 [92%] of 52 vs. 7 [44%] of 16, P = .0002). Similarly, in genealogical studies performed in 38 Dutch DM kindreds, an excess of nonmanifesting male transmitters was noted, which was most conspicuous in the generation immediately preceding that with phenotypic expression of DM. Thus, two separate lines of evidence suggest that the sex of the transmitting parent is an important factor that determines DM allele size in the offspring. On the basis of our data, we estimate that when both parents are asymptomatic, the odds are approximately 2:1 that the father carries the DM mutation. Because expansion of the CTG repeat is more rapid with male transmission, negative selection during spermatogenesis may be required to explain the exclusive maternal inheritance of severe congenital onset DM.

Adult↗
PubMed1993

An informative panel of somatic cell hybrids for physical mapping on human chromosome 19q.

A panel of 22 somatic cell hybrids divides the q arm of human chromosome 19 into 22 ordered subregions. The panel was characterized with respect to 41 genetic markers. In most cases, a single fragment of chromosome 19 was present in each hybrid. In two cell lines the presence of multiple fragments of the chromosome was demonstrated by segregation of these fragments in subclones. On the basis of the results of marker analysis in this panel, the most likely order of the markers tested is MANB-D19S7-PEPD-D19S9-GPI-C/EBP-TGFB1++ +-(CYP2A,BCKDHA,CGM2,NCA)-PSG1-(D19S8, XRCC1)-(ATP1A3,D19S19)-(D19S37,APOC2)-C KM-ERCC2-ERCC1-(D19S116,D19S117)- (D19S118,D19S119, D19S63,p36.1,D19S112,D19S62,D19S51,D19S54, D19S55)-pW39-D19S6-(D19S50,TNNT1)-D19S2 2-(HRC,CGB,FTL,PRKCG)-qter. This gene order is generally consistent with published physical and genetic mapping orders, although some discrepancies exist. By means of a mapping function that relates the frequency of cosegregation of markers to the distance between them, estimates were made of the sizes, in megabases, of the 19q subregions. The relative physical distances between reference markers were compared with published genetic distances for 19q. Excellent correlation was observed, suggesting that the physical distances calculated by this method are predictive of genetic distances in this region of the genome and, therefore, are just as useful in estimating relative positions of markers.

Animals↗
PubMed1992

Isolation of a cDNA for rat CHIP28 water channel: high mRNA expression in kidney cortex and inner medulla.

The cDNA coding for the rat CHIP28 water channel was isolated from a kidney library. At the amino acid level, rat CHIP28 is 93% identical to the recently published human protein (1). Expression of rat CHIP28 mRNA was highest in the renal inner medulla, unchanged during antidiuresis and twice the level expressed in outer cortex, with lower expression levels also apparent in parotid gland, urinary bladder and prostate. The evidence suggests that CHIP28 water channels in the ADH-sensitive collecting tubules are identical to those of the ADH-insensitive proximal convoluted tubules and possibly other tissues specialised in fluid transport.

Amino Acid Sequence↗
PubMed1992

Targeting of the creatine kinase M gene in embryonic stem cells using isogenic and nonisogenic vectors.

Replacement vectors with genomic DNA originating from different mouse strains were used to introduce site-specific mutations into the creatine kinase M (CKM) gene of mouse embryonic stem (ES) cells. Here we demonstrate that in mouse strain 129-derived ES cells, the gene is at least 25-fold more efficiently targeted with an isogenic, 129-derived vector (129-pRV8.3) than with a nonisogenic, BALB/c-specific vector (BALB/c-pRV8.3). The two targeting constructs were identical except for allelic differences which were typed by partial sequencing. These included base pair mismatches (2%) and a polymorphic [GTC]-repeat length variation. Both in separate transfections as well as in cotransfections with mixed vectors, homologous disruption of the CKM gene resulted uniquely from the 129-isogenic DNA. Our data confirm earlier observations on requirements for homologous recombination in pro- and eukaryotic systems and indicate that targeting of the CKM locus is highly sensitive to small sequence differences between cognate segments in the endogenous and incoming DNA.

Animals↗