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Biomedical subjects

S L Hostikka

Publications and source records attributed to S L Hostikka.

15 recordsLinked to original sources
PubMed2001

The paralogous Hox genes Hoxa10 and Hoxd10 interact to pattern the mouse hindlimb peripheral nervous system and skeleton.

The most 5' mouse Hoxa and Hoxd genes, which occupy positions 9-13 and which are related to the Drosophila AbdB gene, are all active in patterning developing limbs. Inactivation of individual genes produces alterations in skeletal elements of both forelimb and hindlimb; inactivation of some of these genes also alters hindlimb innervation. Simultaneous inactivation of paralogous or nonparalogous Hoxa and Hoxd genes produces more widespread alterations, suggesting that combinatorial interactions between these genes are required for proper limb patterning. We have examined the effects of simultaneous inactivation of Hoxa10 and Hoxd10 on mouse hindlimb skeletal and nervous system development. These paralogous genes are expressed at lumbar and sacral levels of the developing neural tube and surrounding axial mesoderm as well as in developing forelimb and hindlimb buds. Double-mutant animals demonstrated impaired locomotor behavior and altered development of posterior vertebrae and hindlimb skeletal elements. Alterations in hindlimb innervation were also observed, including truncations and deletions of the tibial and peroneal nerves. Animals carrying fewer mutant alleles show similar, but less extreme phenotypes. These observations suggest that Hoxa10 and Hoxd10 coordinately regulate skeletal development and innervation of the hindlimb.

Animals↗
PubMed1998

The mouse Hoxc11 gene: genomic structure and expression pattern.

The mouse and human Hox complex consists of 39 genes in four linkage groups (A-D). Although the structure and expression patterns of most of these genes have been reported, the 5' members of the Hox C linkage group have been only partially characterized. Herein we report the primary and genomic structure of the mouse Hoxc11 gene as well as its expression pattern. The Hoxc11 gene encodes a 304 amino acid protein which is translated from a 2.2 kb transcript, derived from two exons. Hoxc11 mRNA is found in the most posterior region of the developing embryo commencing at 9.5 days of gestation. Expression is detected in the posterior neural tube, dorsal root ganglia, prevertebrae and hindlimbs. Expression is also found in metanephric mesenchyme which, later in development, becomes restricted to the cortical region of the developing kidney. In the developing genitalia, prominent expression is first observed in the posterior urogenital sinus that gives rise to the urethra, vagina and prostate. Later, expression is seen in paramesonephric and mesonephric ducts and in the genital tubercle. In the hindlimbs, Hoxc11 expression is seen in the mesenchyme posterior to the region forming the femur and fibula, but does not extend anteriorly to the region giving rise to the tibia or distally to the tarsal bones.

Amino Acid Sequence↗
PubMed1993

Molecular genetics of Alport syndrome.

Alport syndrome is a progressive hereditary kidney disease characterized by hematuria, sensorineural hearing loss and ocular lesions with structural defects in the glomerular basement membrane (GBM). The gene frequency has been estimated to be 1:5000. The disease is primarily X chromosome-linked, but autosomal forms have also been reported. The X-linked form has been shown to be caused by mutations in a recently identified alpha 5(IV) collagen chain gene (COL4A5). We have isolated cDNA clones for providing the entire primary structure of the human alpha 5(IV) chain. The gene has been located to the Xq22 region. Using antibodies against synthetic peptides, the alpha 5(IV) chain was shown to be located in the kidney only in the glomerular basement membrane. Thus far, the exon-intron structure has been determined for a large portion of the gene which probably has a size of over 200 kb. Numerous different mutations have been identified in the COL4A5 gene. The mutations include single base mutations, large deletions and other major rearrangements such as inversion and duplication. The consequences of the mutations observed can be considered sufficient to cause structural and functional defects in the type IV collagen molecule and, therefore, also the GBM network. This, in turn can explain the disruption of the GBM and hematuria occurring in these Alport patients. Alport syndrome is the first genetic basement membrane and kidney disease whose gene has been cloned. These recent results have enabled the development of antibodies and DNA probes for accurate diagnosis of Alport syndrome.

Chromosome Mapping↗
PubMed1992

Different mutations in the COL4A5 collagen gene in two patients with different features of Alport syndrome.

Alport syndrome is a hereditary renal disease in which progressive renal failure is often accompanied by sensorineural deafness and ocular abnormalities. Recently, mutations were detected in the type IV collagen alpha 5 chain gene in Alport syndrome patients. We searched for mutations in this gene in 18 unrelated patients, and in two patients abnormalities were detected. In the gene of patient BB we identified a complex deletion, which included the exons encoding the non-collagenous domain and part of the collagenous region. This patient showed early onset nephritis (end-stage renal disease at 17 years) with deafness. Within a year after receiving a kidney from an unrelated donor, he developed an antiglomerular basement membrane nephritis. In patient WJ a point-mutation was detected, changing a tryptophane into a serine in the non-collagenous domain. His clinical features are milder (renal failure at 33 years, no hearing loss), and a recent renal allograft did not provoke antiglomerular basement membrane disease. These initial data suggest that differences in the extent of disruption of the non-collagenous domain may correlate with the severity and/or heterogeneity of Alport syndrome and with the development of nephritis in renal allografts.

Amino Acid Sequence↗
PubMed1991

Characterization of the 3' half of the human type IV collagen alpha 5 gene that is affected in the Alport syndrome.

We have determined the exon-intron structure of the 3' half of the gene for the human type IV collagen alpha 5 chain that is affected in X-chromosome-linked Alport syndrome. Six overlapping lambda phage genomic clones containing exons 1-14 (as counted from the 3' end) and two additional overlapping genomic clones containing exons 16-19 spanned a total of 60 kb, 9.5 kb of which were the 3' flanking region. The exon-intron structure was elucidated by restriction enzyme mapping, nucleotide sequencing, and heteroduplex analyses. The sequences of all of the 19 most 3' exons and their flanking sequences were determined from the genomic clones, with the exception of exon 15, which was sequenced after amplification from genomic DNA with the polymerase chain reaction. The results show that the genes for the alpha 5(IV) and alpha 1(IV) chains have an almost identical exon size pattern in the 3' half. In contrast, there is not a clear conservation of intron sizes between the two genes, although both genes may have a similar total size. The current results have allowed the identification of three mutations in the alpha 5(IV) gene in three kindreds with Alport syndrome, and the gene structure and sequencing data presented should facilitate the analysis of other as yet unidentified mutations in this heterogeneous genetic disease.

Amino Acid Sequence↗
PubMed1991

Single base mutation in alpha 5(IV) collagen chain gene converting a conserved cysteine to serine in Alport syndrome.

We have identified a point mutation in the type IV collagen alpha 5 chain gene (COL4A5) in Alport syndrome. Variant PstI (Barker et al., 1990, Science 248, 1224-1227), and BglII restriction sites with complete linkage with the Alport phenotype have been found in the 3' end of the COL4A5 gene in the large Utah Kindred P. The approximate location of the variant sites was determined by restriction enzyme mapping, after which this region of the gene (1028 bp) was amplified with the polymerase chain reaction (PCR) from DNA of normal and affected individuals for sequencing analysis. The PCR products showed the absence or presence of the variant PstI and BglII sites in DNA from normal and affected individuals, respectively. DNA sequencing revealed a single base change in exon 3 (from the 3' end) in DNA from affected individuals, changing the TGT codon of cysteine to the TCT codon for serine. This single base mutation also generated new restriction sites for PstI and BglII. The mutation involves a cysteine residue that has remained conserved in the carboxyl-end noncollagenous domain (NC domain) of all known type IV collagen alpha chains from Drosophila to man. It is presumably crucial for maintaining the right conformation of the NC domain, which is important for both triple-helix formation and the formation of intermolecular cross-links of type IV collagen molecules.

Bacterial Proteins↗
PubMed1990

Identification of mutations in the COL4A5 collagen gene in Alport syndrome.

X-linked Alport syndrome is a hereditary glomerulonephritis in which progressive loss of kidney function is often accompanied by progressive loss of hearing. Ultrastructural defects in glomerular basement membranes (GBM) of Alport syndrome patients implicate an altered structural protein as the cause of nephritis. The product of COL4A5, the alpha 5(IV) collagen chain, is a specific component of GBM within the kidney, and the gene maps to the same X chromosomal region as does Alport syndrome. Three structural aberrations were found in COL4A5, in intragenic deletion, a Pst I site variant, and an uncharacterized abnormality, which appear to cause nephritis and deafness, with allele-specific severity, in three Alport syndrome kindreds in Utah.

Blotting, Southern↗
PubMed1990

Identification of a distinct type IV collagen alpha chain with restricted kidney distribution and assignment of its gene to the locus of X chromosome-linked Alport syndrome.

We have identified and extensively characterized a type IV collagen alpha chain, referred to as alpha 5(IV). Four overlapping cDNA clones isolated contain an open reading frame for 543 amino acid residues of the carboxyl-terminal end of a collagenous domain, a 229-residue carboxyl-terminal noncollagenous domain, and 1201 base pairs coding for a 3' untranslated region. The collagenous Gly-Xaa-Yaa repeat sequence has five imperfections that coincide with those in the corresponding region of the alpha 1(IV) chain. The noncollagenous domain has 12 conserved cysteine residues and 83% and 63% sequence identity with the noncollagenous domains of the alpha 1(IV) and alpha 2(IV) chains, respectively. The alpha 5(IV) chain has less sequence identity with the putative bovine alpha 3(IV) and alpha 4(IV) chains. Antiserum against an alpha 5(IV) synthetic peptide stained a polypeptide chain of about 185 kDa by immunoblot analysis and immunolocalization of the chain in human kidney was almost completely restricted to the glomerulus. The gene was assigned to the Xq22 locus by somatic cell hybrids and in situ hybridization. This may be identical or close to the locus of the X chromosome-linked Alport syndrome that is believed to be a type IV collagen disease.

Amino Acid Sequence↗
PubMed1988

The complete primary structure of the alpha 2 chain of human type IV collagen and comparison with the alpha 1(IV) chain.

The complete primary structure of the human type IV collagen alpha 2(IV) chain has been determined by nucleotide sequencing of cDNA clones. The overlapping cDNA clones cover 6,257 base pairs with a 5'-untranslated region of 283 base pairs, the 5,136-base pair open reading frame, and the 3'-untranslated region of 838 base pairs. The predicted amino acid sequence demonstrates that the complete translation product consists of 1,712 residues corresponding in molecular weight to 167,560. The translated polypeptide has a signal peptide of 36 amino acids, an amino-terminal noncollagenous part of 21 residues, a 1,428-residue collagenous domain with 23 interruptions, and a carboxyl-terminal noncollagenous (NC) domain of 227 residues. The calculated molecular mass of the mature human alpha 2(IV) chain is 163,774 Da.

Amino Acid Sequence↗
PubMed1988

The structural genes for alpha 1 and alpha 2 chains of human type IV collagen are divergently encoded on opposite DNA strands and have an overlapping promoter region.

Many of the genes of simple organisms with small genomes are encoded on opposite DNA strands so that the genes either overlap or one gene is nested within another gene (Normark, S., Bergström, S., Edlund, T., Grundström, T., Jaurin, B., Lindberg, F.P., and Olsson, D. (1983) Annu. Rev. Genet. 17, 499-525; Chen, C., Malone, T., Beckendorf, S.K., and Davis, R.L. Nature (1987) 329, 721-724). In contrast, most of the genes of complex organisms are dispersed in the genome in widely separated locations. Here, we report that the genes for the alpha 1 and alpha 2 chains of human type IV collagen are encoded on opposite DNA strands from loci that are so closely located that they may be separated by as little as 42 base pairs. The results provide the first description of two structural genes from a complex organism that code for two polypeptide chains of the same protein molecule but have overlapping 5'-flanking regions.

Amino Acid Sequence↗
PubMed1987

Extensive structural differences between genes for the alpha 1 and alpha 2 chains of type IV collagen despite conservation of coding sequences.

Analysis of the structure of the 3'-end of the human alpha 2(IV) gene demonstrated that the alpha 1(IV) and alpha 2(IV) genes have diverged extensively in spite of the apparent homology of the respective gene products. The NC-1 domain and the 3'-untranslated region are encoded by three exons in the alpha 2(IV) gene but five exons in the alpha 1(IV) gene. The two introns present in the NC-1 domain coding part of the alpha 2(IV) gene had the same location as two of the introns of the alpha 1(IV) gene. The junction exon in the alpha 2(IV) gene contains 53 bp coding for Gly-X-Y sequences whereas there are 71 bp in the alpha 1(IV) gene. Three other Gly-X-Y coding exons studied from the human alpha 2(IV) gene have sizes that differ from corresponding exons in the alpha 1(IV) gene and only one intron location matches here between the two genes. None of the exons studied has 54 bp or multiples thereof.

Animals↗
PubMed1987

Nucleotide sequence coding for the human type IV collagen alpha 2 chain cDNA reveals extensive homology with the NC-1 domain of alpha 1 (IV) but not with the collagenous domain or 3'-untranslated region.

We have isolated two overlapping cDNA clones that provide the complete nucleotide sequence coding for the NC-1 domain and 3'-untranslated region of the alpha 2 chain of human type IV collagen as well as a sequence encoding 232 residues of the collagenous domain. An extensive homology was observed between the sequences of the NC-1 domain of the alpha 1(IV) and alpha 2(IV) chains, but considerably less between the sequences encoding collagenous and 3'-untranslated regions. There were four interruptions in the collagenous sequence studied whereas the comparable region of the alpha 1(IV) chain had only two. A potential oligosaccharide attachment site was found in a 6-residue long interruption of the collagenous domain but none in the NC-1 domain.

Amino Acid Sequence↗