About
97
Publications
13,676
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
5,133
Citations
Introduction
Skills and Expertise
Publications
Publications (97)
Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disorder affecting tissues of mesenchymal origin. Most individuals with HGPS harbor a de novo c.1824C > T (p.G608G) mutation in the gene encoding lamin A (LMNA), which activates a cryptic splice donor site resulting in production of the toxic "progerin" protein. Clinical manifestation...
Melorheostosis is a rare sclerosing dysostosis characterized by asymmetric exuberant bone formation. Recently, we reported that somatic mosaicism for MAP2K1-activating mutations causes radiographical "dripping candle wax" melorheostosis. We now report somatic SMAD3 mutations in bone lesions of four unrelated patients with endosteal pattern melorheo...
Null mutations in CRTAP or P3H1, encoding cartilage-associated protein and prolyl 3-hydroxylase 1, cause the severe bone dysplasias, types VII and VIII osteogenesis imperfecta. Lack of either protein prevents formation of the ER prolyl 3-hydroxylation complex, which catalyzes 3Hyp modification of types I and II collagen and also acts as a collagen...
Covalent intermolecular cross-linking of collagen is essential for tissue stability. Recent studies have demonstrated that cyclophilin B (CypB), an endoplasmic reticulum (ER)-resident peptidyl-prolyl cis-trans isomerase, modulates lysine (Lys) hydroxylation of type I collagen impacting cross-linking chemistry. However, the extent of modulation, the...
Mutations in the type I procollagen C-propeptide occur in ~6.5% of Osteogenesis Imperfecta (OI) patients. They are of special interest because this region of procollagen is involved in α chain selection and folding, but is processed prior to fibril assembly and is absent in mature collagen fibrils in tissue. We investigated the consequences of seve...
Melorheostosis is a rare non-hereditary condition characterized by dense hyperostotic lesions with radiographic “dripping candle wax” appearance. Somatic activating mutations in MAP2K1 have recently been identified as a cause of melorheostosis. However, little is known about the development, composition, structure, and mechanical properties of the...
Higher skeletal fragility has been established for the Brtl/+ mouse model of osteogenesis imperfecta at the whole bone level, but previous investigations of mechanical properties at the bone material level were inconclusive. Bone material was analyzed separately at endosteal (ER) and periosteal regions (PR) on transverse femoral midshaft sections f...
Melorheostosis is a sporadic disease of uncertain etiology characterized by asymmetric bone overgrowth and functional impairment. Using whole exome sequencing, we identify somatic mosaic MAP2K1 mutations in affected, but not unaffected, bone of eight unrelated patients with melorheostosis. The activating mutations (Q56P, K57E and K57N) cluster tigh...
Osteogenesis imperfecta is a genetic disorder characterized by low bone mass, decreased bone strength, increased bone fragility, and shortened stature. Autosomal dominant osteogenesis imperfecta is caused by mutations in the type I collagen genes (COL1A1 and COL1A2), whereas recessive osteogenesis imperfecta is caused by mutations in genes encoding...
Cyclophilin B (CypB) is an endoplasmic reticulum-resident protein that regulates collagen folding, and also contributes to prolyl 3-hydroxylation (P3H) and lysine (Lys) hydroxylation of collagen. In this study, we characterized dentin type I collagen in CypB null (KO) mice, a model of recessive osteogenesis imperfecta type IX, and compared to those...
Context:
Recessive mutations in TMEM38B cause type XIV osteogenesis imperfecta (OI) by dysregulating intracellular calcium flux.
Objectives:
Clinical and bone material phenotype description and osteoblast differentiation studies.
Design and setting:
Natural history study in paediatric research centres.
Patients:
Eight patients with type XIV...
Limited detoxification capacity often directs aggregation-prone, potentially hazardous misfolded proteins to be deposited in designated cytosolic compartments known as "aggresomes". The roles of aggresomes as cellular quality control centers, and the cellular origin of the deposits contained within these structures, remain to be characterized. Here...
Recessive osteogenesis imperfecta (OI) is caused by defects in proteins involved in post-translational interactions with type I collagen. Recently, a novel form of moderately severe OI caused by null mutations in TMEM38B was identified. TMEM38B encodes the ER membrane monovalent cation channel, TRIC-B, proposed to counterbalance IP3R-mediated Ca2+...
TMEM38B Bedouin founder mutation results in minimal in-frame transcripts due to alternative splicing.
(A) Characterization of alternative splicing in P1 fibroblasts, including 4 out-of-frame and 1 in-frame transcript. Arrows represent positions of primers used for RT-PCR amplification. (*) represents positions of premature termination codons in alt...
Altered ER [Ca2+] does not delay cyclophilin B-mediated collagen folding.
Assay for intracellular folding of type I collagen in Proband 1 (P1) fibroblast cultures versus normal control (C) fibroblasts. The equivalent rate of trypsin-resistant collagen alpha chains suggests normal functioning of cyclophilin B-mediated peptidyl-prolyl cis-trans isome...
Pulse-chase analysis of collagen secretion.
Type I collagen secretion kinetics are equivalent in Proband 1 (P1) and normal control (C) fibroblast cultures. However, comparison of the quantity of collagen in cell and media fractions at each timepoint demonstrate a nearly 40% decrease in the amount of collagen in proband samples.
(TIF)
Relative expression of TRIC isoforms and ER calcium release channels.
(A) Relative mRNA transcript levels of TMEM38A and TMEM38B in normal and proband fibroblasts and osteoblasts. Transcript levels were normalized to three reference genes (ACTB, B2M and GAPDH) and are expressed relative to normal control fibroblast TMEM38B transcripts. (B) Levels o...
Decreased Ca2+ mobilization in TRIC-B deficient cells.
(A) Ionomycin-stimulated Ca2+ release to deplete all intracellular stores, followed by ATP-stimulated IP3R-mediated Ca2+ release, demonstrates absence of replenishment of ER Ca2+ stores in P1 fibroblasts. (B) Decreased Ca2+ release and delayed return to baseline following ionomycin-stimulated C...
Pulse-chase analysis of pericellular procollagen processing.
Procollagens secreted by Proband 1 (OI) and normal control (C) fibroblasts were collected at 1-day intervals and separated by SDS-Urea PAGE to follow their processing by pericellular propeptidases. There is an increase in the fraction of type I procollagen molecules that are resistant to...
Validation of normal primary fibroblast control cell lines.
The relative expression of genes of interest in three independent normal control fibroblast cell lines (NL C1, C2 and C3) was evaluated by real-time RT-PCR. Expression levels were compared to values obtained for pooled cDNA (NL pool) derived from each control cell line. Only COL1A1 express...
Amount of type I collagen deposited into extracellular matrix in culture is decreased in the absence of TRIC-B.
Normal control (C) and Proband 1 (P1) fibroblasts were grown to confluence and stimulated for collagen synthesis for 2 weeks with ascorbate. Following a 24-hr pulse of labeled collagen, secreted collagens were collected and extracellular...
Osteogenesis imperfecta (OI) is a collagen-related bone dysplasia. We identified an X-linked recessive form of OI caused by defects in MBTPS2, which encodes site-2 metalloprotease (S2P). MBTPS2 missense mutations in two independent kindreds with moderate/severe OI cause substitutions at highly conserved S2P residues. Mutant S2P has normal stability...
Supplementary Figures 1-9, Supplementary Tables 1-8 and Supplementary References
Osteogenesis imperfecta (OI) is a collagen-related bone dysplasia. We identified an X-linked recessive form of OI caused by defects in MBTPS2, which encodes site-2 metalloprotease (S2P). MBTPS2 missense mutations in two independent kindreds with moderate/severe OI cause substitutions at highly conserved S2P residues. Mutant S2P has normal stability...
Deficiency of Cyclophilin B (CyPB) causes recessively inherited Type IX osteogenesis imperfecta, a moderately severe to lethal bone dysplasia. CyPB, encoded by PPIB, is an ER-resident peptidyl-prolyl cis-trans isomerase (PPIase) that catalyzes the rate-limiting step in collagen folding, and also functions as a component of the collagen prolyl 3-hyd...
Covalent intermolecular cross-linking provides collagen fibrils with stability. The cross-linking chemistry is tissue-specific
determined primarily by the state of lysine hydroxylation at the specific sites. A recent study on cyclophilin B (CypB) null
mice, a model of recessive osteogenesis imperfecta, demonstrated that lysine hydroxylation at the...
Do different neurodegenerative maladies emanate from the failure of a mutual protein folding mechanism? We have addressed this question by comparing mutational patterns that are linked to the manifestation of distinct neurodegenerative disorders and identified similar neurodegeneration-linked proline substitutions in the prion protein and in presen...
Context:
Patients with type V osteogenesis imperfecta (OI) are heterozygous for a dominant IFITM5 c.-14C>T mutation, which adds five residues to the N terminus of bone-restricted interferon-induced transmembrane-like protein (BRIL), a transmembrane protein expressed in osteoblasts. Type V OI skeletal findings include hyperplastic callus formation,...
Osteogenesis imperfecta (OI) types V and VI are caused, respectively, by a unique dominant mutation in IFITM5, encoding BRIL, a transmembrane ifitm-like protein most strongly expressed in the skeletal system, and recessive null mutations in SERPINF1, encoding pigment epithelium-derived factor (PEDF). We identified a 25-year-old woman with severe OI...
Cyclophilin B (CyPB), encoded by PPIB, is an ER-resident peptidyl-prolyl cis-trans isomerase (PPIase) that functions independently and as a component of the collagen prolyl 3-hydroxylation complex. CyPB is proposed to be the major PPIase catalyzing the rate-limiting step in collagen folding. Mutations in PPIB cause recessively inherited osteogenesi...
Recessive mutations in FKBP10 at 17q21.2, encoding FKBP65, cause both osteogenesis imperfecta (OI) and Bruck syndrome (OI plus congenital contractures). Contractures are a variable manifestation of null/missense FKBP10 mutations. Kuskokwim syndrome (KS) is an autosomal recessive congenital contracture disorder found among Yup'ik Eskimos. Linkage ma...
Introduction: Osteogenesis imperfecta (OI) is a genetically heterogeneous disorder characterized by bone fragility. OI type V, with autosomal dominant inheritance, is characterized by ossification of the forearm interosseus membrane, radiodense metaphyseal bands, propensity for hyperplastic callus formation, and mesh-like lamellation on bone histol...
Introduction: Recessive osteogenesis imperfecta (OI) is caused by mutations in genes encoding proteins involved in post-translational interactions with type I collagen. Types VIIIX OI involve defects in the collagen prolyl 3-hydroxylation complex, which modifies α1(I)Pro986. PPIB encodes CyPB, a complex component with PPIase activity and the major...
The Brtl/+ mouse is a knock-in model for osteogenesis imperfecta type IV in which a Gly349Cys substitution was introduced into one COL1A1 allele. To gain insight into the changes in dentin structure and mineral composition in these transgenic mice, the objective of this study was to use microcomputed tomography (micro-CT), scanning electron microsc...
Recessive osteogenesis imperfecta (OI) is caused by defects in genes whose products interact with type I collagen for modification and/or folding. We identified a Palestinian pedigree with moderate and lethal forms of recessive OI caused by mutations in FKBP10 or PPIB, which encode endoplasmic reticulum resident chaperone/isomerases FKBP65 and CyPB...
Type I collagen is the most abundant protein in mammals, and is a vital part of the extracellular matrix for numerous tissues. Despite collagen's importance, little is known about its nanoscale morphology in tissues and how morphology relates to mechanical function. This study probes nanoscale structure and mechanical properties of collagen as a fu...
Recessive osteogenesis imperfecta (OI) is caused by defects in genes whose products interact with type I collagen for modification and/or folding. We identified a Palestinian pedigree with moderate and lethal forms of recessive OI caused by mutations in FKBP10 or PPIB, which encode endoplasmic reticulum resident chaperone/isomerases FKBP65 and CyPB...
Deficiency of prolyl 3-hydroxylase 1, encoded by LEPRE1, causes recessive osteogenesis imperfecta (OI). We previously identified a LEPRE1 mutation exclusively in African Americans and contemporary West Africans. We hypothesized that this allele originated in West Africa and was introduced to the Americas with the Atlantic slave trade. We aimed to d...
Valli M, Barnes AM, Gallanti A, Cabral WA, Viglio S, Weis MA, Makareeva E, Eyre D, Leikin S, Antoniazzi F, Marini JC, Mottes M. Deficiency of CRTAP in non-lethal recessive osteogenesis imperfecta reduces collagen deposition into matrix.
Deficiency of any component of the ER-resident collagen prolyl 3-hydroxylation complex causes recessive osteogene...
A new paradigm has emerged for osteogenesis imperfecta as a collagen-related disorder. The more prevalent autosomal dominant forms of osteogenesis imperfecta are caused by primary defects in type I collagen, whereas autosomal recessive forms are caused by deficiency of proteins which interact with type I procollagen for post-translational modificat...
Osteogenesis imperfecta is a heritable disorder that causes bone fragility. Mutations in type I collagen result in autosomal dominant osteogenesis imperfecta, whereas mutations in either of two components of the collagen prolyl 3-hydroxylation complex (cartilage-associated protein [CRTAP] and prolyl 3-hydroxylase 1 [P3H1]) cause autosomal recessive...
Null mutations in cartilage-associated protein (CRTAP) and prolyl 3-hydroxylase 1 (P3H1/LEPRE1) cause types VII and VIII OI, respectively, two novel recessive forms of osteogenesis imperfecta (OI) with severe to lethal
bone dysplasia and overmodification of the type I collagen helical region. CRTAP and P3H1 form a complex with cyclophilin
B (CyPB)...
Classical osteogenesis imperfecta (OI) is a dominant genetic disorder of connective tissue caused by mutations in either of the two genes encoding type I collagen, COL1A1 and COL1A2. Recent investigations, however, have generated a new paradigm for OI incorporating many of the prototypical features that distinguish dominant and recessive conditions...
The Brtl mouse, a knock-in model for moderately severe osteogenesis imperfecta (OI), has a G349C substitution in half of type I collagen alpha1(I) chains. We studied the cellular contribution to Brtl bone properties. Brtl cortical and trabecular bone are reduced before and after puberty, with BV/TV decreased 40-45%. Brtl ObS/BS is comparable to wil...
The 33-kDa matrix protein SPARC (BM-40, osteonectin) binds several collagen types with moderate affinity. The collagen-binding site resides in helix alphaA of the extracellular calcium-binding domain of SPARC and is partially masked by helix alphaC. Previously, we found that the removal of helix alphaC caused a 10-fold increase in the affinity of S...
Type I collagen, the predominant protein of vertebrates, polymerizes with type III and V collagens and non-collagenous molecules into large cable-like fibrils, yet how the fibril interacts with cells and other binding partners remains poorly understood. To help reveal insights into the collagen structure-function relationship, a data base was assem...
We investigated regions of different helical stability within human type I collagen and discussed their role in intermolecular interactions and osteogenesis imperfecta (OI). By differential scanning calorimetry and circular dichroism, we measured and mapped changes in the collagen melting temperature (DeltaTm) for 41 different Gly substitutions fro...
Prolyl 3-hydroxylase 1 (P3H1), cartilage-associated protein (CRTAP) and cyclophilin B (CyPB) form a complex in the endoplasmic reticulum which is responsible for 3-hydroxylation of a limited number of proline residues in types I, II and V collagens. In this complex, CRTAP serves the role of helper protein, while P3H1 provides the enzymatic activity...
A recessive form of severe osteogenesis imperfecta that is not caused by mutations in type I collagen has long been suspected. Mutations in human CRTAP (cartilage-associated protein) causing recessive bone disease have been reported. CRTAP forms a complex with cyclophilin B and prolyl 3-hydroxylase 1, which is encoded by LEPRE1 and hydroxylates one...
The most common mutations in type I collagen causing types II-IV osteogenesis imperfecta (OI) result in substitution for glycine in a Gly-Xaa-Yaa triplet by another amino acid. We delineated a Y-position substitution in a small pedigree with a combined OI/Ehlers-Danlos Syndrome (EDS) phenotype, characterized by moderately decreased DEXA z-score (-1...
Osteogenesis imperfecta (OI) is a generalized disorder of connective tissue characterized by fragile bones and easy susceptibility to fracture. Most cases of OI are caused by mutations in type I collagen. We have identified and assembled structural mutations in type I collagen genes (COL1A1 and COL1A2, encoding the proalpha1(I) and proalpha2(I) cha...
Classic osteogenesis imperfecta, an autosomal dominant disorder associated with osteoporosis and bone fragility, is caused by mutations in the genes for type I collagen. A recessive form of the disorder has long been suspected. Since the loss of cartilage-associated protein (CRTAP), which is required for post-translational prolyl 3-hydroxylation of...
The biochemical test for osteogenesis imperfecta (OI) detects structural abnormalities in the helical region of type I collagen as delayed electrophoretic migration of alpha chains on SDS-urea-PAGE. Sensitivity of this test is based on overmodification of alpha chains in helices with a glycine substitution or other structural defect. The limits of...
We demonstrate that 85 N-terminal amino acids of the α1(I) chain participate in a highly stable folding domain, acting as
the stabilizing anchor for the amino end of the type I collagen triple helix. This anchor region is bordered by a microunfolding
region, 15 amino acids in each chain, which include no proline or hydroxyproline residues and conta...
We demonstrate that 85 N-terminal amino acids of the α1(I) chain participate in a highly stable folding domain, acting as
the stabilizing anchor for the amino end of the type I collagen triple helix. This anchor region is bordered by a microunfolding
region, 15 amino acids in each chain, which include no proline or hydroxyproline residues and conta...
Patients with OI/EDS form a distinct subset of osteogenesis imperfecta (OI) patients. In addition to skeletal fragility, they
have characteristics of Ehlers-Danlos syndrome (EDS). We identified 7 children with types III or IV OI, plus severe large
and small joint laxity and early progressive scoliosis. In each child with OI/EDS, we identified a mut...
Skin fibroblasts from the majority of patients with the clinical diagnosis of Ehlers-Danlos syndrome type VI (EDS VI; kyphoscoliosis type), have significantly decreased lysyl hydroxylase (LH) activity due to mutations in the LH1 gene (classified as EDS VIA: OMIM no. 225400). A rare condition exists in which patients are clinically similar but have...
Here we report the structural and functional studies of collagen from the Brtl mouse, a heterozygous knock-in model for Osteogenesis Imperfecta, which has a G349C substitution introduced in one col1a1 allele. We observed that 25+/-5% of alpha 1(I) chains in different tissues and in different extracts from matrix deposited by cultured cells were S-S...
Individuals with mosaicism for the autosomal dominant bone dysplasia osteogenesis imperfecta (OI) are generally identified by having more than one affected child. The mosaic carriers have both normal and mutant cell populations in somatic and germline tissues but are unaffected or minimally affected by the type I collagen mutation that manifests cl...
We are indebted to the mosaic carriers and their families, for their longstanding support of OI research; to C. Michael Reing, M.D., and Elizabeth Hopkins, B.S.N., for the iliac crest biopsy of the mosaic carrier of OI type IV; to Laura Tosi, M.D., for osteotomy bone chips from the son of the mosaic carrier of OI type IV; to Lawrence Loesel, M.D.,...
The majority of collagen mutations causing osteogenesis imperfecta (OI) are glycine substitutions that disrupt formation of the triple helix. A rare type of collagen mutation consists of a duplication or deletion of one or two Gly-X-Y triplets. These mutations shift the register of collagen chains with respect to each other in the helix but do not...
Previous in vitro data on type I collagen self-assembly into fibrils suggested that the amino acid 776-796 region of the alpha1(I) chain is crucial for fibril formation because it serves as the recognition site for the telopeptide of a docking collagen monomer. We used a natural collagen mutation with a deletion of amino acids 766-801 to confirm th...
The majority of osteogenesis imperfecta (OI) is caused by substitutions for glycine residues in the two alpha chains of type I collagen. Since only 4% of possible nucleotide changes in type I collagen glycine codons would result in a glutamic acid substitution, these are predicted to be infrequent. Only one glutamic acid substitution in type I coll...
We studied four affected individuals from a family of three generations with Ehlers-Danlos Syndrome II. Type V collagen transcripts of affected individuals were screened by reverse transcriptase-polymerase chain reaction. Amplification of the exon 9-28 region of alpha1(V) yielded normal and larger products from the proband. Sequencing of cDNA revea...
A human CB2 recombinant baculovirus (AcNPV-hCB2) was generated by site-specific transposition and employed to express the human CB2 cannabinoid receptor. Northern analysis of total RNA from Spodoptera frugiperda (Sf9) insect cells infected with AcNPV-hCB2 revealed novel expression of a unique 2.3 kb transcript when probed with hCB2 cDNA. This trans...
In three cases of type IV osteogenesis imperfecta (OI), we identified unique point mutations in type I collagen alpha1(I) cDNA. In two cases, the appearance of dimers indicated the presence of cysteine substitutions in the alpha1(I) protein chain. Cyanogen bromide digestion localized these cross-links to CB8 and 3, respectively. In the third case,...
