transforming-growth-factor-beta and Growth-Disorders

Myhre syndrome (MS) is a developmental disorder characterized by typical facial dysmorphism, thickened skin, joint limitation and muscular pseudohypertrophy. Other features include brachydactyly, short stature, intellectual deficiency with behavioral problems and deafness. We identified SMAD4 as the gene responsible for MS. The identification of SMAD4 mutations in Laryngotracheal stenosis, Arthropathy, Prognathism and Short stature (LAPS) cases supports that LAPS and MS are a unique entity. The long-term follow up of patients shows that these conditions are progressive with life threatening complications. All mutations are de novo and changing in the majority of cases Ile500, located in the MH2 domain involved in transcriptional activation. We further showed an impairment of the transcriptional regulation via TGFβ target genes in patient fibroblasts. Finally, the absence of SMAD4 mutations in three MS cases may support genetic heterogeneity.

Topics: Adolescent; Adult; Child; Child, Preschool; Cryptorchidism; Disease Progression; Facies; Female; Fibroblasts; Follow-Up Studies; Genetic Heterogeneity; Genotype; Growth Disorders; Hand Deformities, Congenital; Humans; Hypertrophy; Intellectual Disability; Joint Diseases; Male; Mutation; Phenotype; Smad4 Protein; Transcriptional Activation; Transforming Growth Factor beta

Human bone contains an abundance of polypeptide growth factors. These growth factors stimulate the proliferation and activity of bone cells and can stimulate bone formation. Data from this laboratory and others suggest that bone growth factors may act to couple bone formation to resorption to maintain bone mass during remodeling. Research is underway to study these growth factors in bones and teeth, and their possible roles in both the pathogenesis and the treatments of osteoporosis and dental diseases.

Topics: Animals; Bone and Bones; Bone Remodeling; Dentin; Estrogens; Growth Disorders; Growth Substances; Humans; Odontoblasts; Odontogenesis; Osteoarthritis; Osteogenesis; Osteoporosis; Periodontal Diseases; Somatomedins; Tooth; Transforming Growth Factor beta; Vitamin D Deficiency

Acromelic dysplasias are a group of rare musculoskeletal disorders that collectively present with short stature, pseudomuscular build, stiff joints, and tight skin. Acromelic dysplasias are caused by mutations in genes (FBN1, ADAMTSL2, ADAMTS10, ADAMTS17, LTBP2, and LTBP3) that encode secreted extracellular matrix proteins, and in SMAD4, an intracellular coregulator of transforming growth factor-β (TGF-β) signaling. The shared musculoskeletal presentations in acromelic dysplasias suggest that these proteins cooperate in a biological pathway, but also fulfill distinct roles in specific tissues that are affected in individual disorders of the acromelic dysplasia group. In addition, most of the affected proteins directly interact with fibrillin microfibrils in the extracellular matrix and have been linked to the regulation of TGF-β signaling. Together with recently developed knockout mouse models targeting the affected genes, novel insights into molecular mechanisms of how these proteins regulate musculoskeletal development and homeostasis have emerged. Here, we summarize the current knowledge highlighting pathogenic mechanisms of the different disorders that compose acromelic dysplasias and provide an overview of the emerging biological roles of the individual proteins that are compromised. Finally, we develop a conceptual model of how these proteins may interact and form an "acromelic dysplasia complex" on fibrillin microfibrils in connective tissues of the musculoskeletal system.

Topics: Animals; Bone Diseases, Developmental; Cryptorchidism; Disease Models, Animal; Dwarfism; Facies; Fibrillins; Growth Disorders; Hand Deformities, Congenital; Humans; Intellectual Disability; Joints; Limb Deformities, Congenital; Mice; Mice, Knockout; Microfibrils; Musculoskeletal Abnormalities; Skin Abnormalities; Smad4 Protein; Transforming Growth Factor beta; Weill-Marchesani Syndrome

SMAD4 encodes a member of the SMAD family of proteins involved in the TGF-β signaling pathway. Potentially heritable, autosomal dominant, gain-of-function heterozygous variants of SMAD4 cause a rare developmental disorder, the Myhre syndrome, which is associated with a wide range of developmental and post-developmental phenotypes that we now characterize as a novel segmental progeroid syndrome. Whole-exome sequencing of a patient referred to our International Registry of Werner Syndrome revealed a heterozygous p.Arg496Cys variant of the SMAD4 gene. To investigate the role of SMAD4 mutations in accelerated senescence, we generated cellular models overexpressing either wild-type SMAD4 or mutant SMAD4-R496C in normal skin fibroblasts. We found that cells expressing the SMAD4-R496C mutant exhibited decreased proliferation and elevated expression of cellular senescence and inflammatory markers, including IL-6, IFNγ, and a TGF-β target gene, PAI-1. Here we show that transient exposure to TGF-β, an inflammatory cytokine, followed by chronic IFNγ stimulation, accelerated rates of senescence that were associated with increased DNA damage foci and SMAD4 expression. TGF-β, IFNγ, or combinations of both were not sufficient to reduce proliferation rates of fibroblasts. In contrast, TGF-β alone was able to induce preadipocyte senescence via induction of the mTOR protein. The mTOR inhibitor rapamycin mitigated TGF-β-induced expression of p21, p16, and DNA damage foci and improved replicative potential of preadipocytes, supporting the cell-specific response to this cytokine. These findings collectively suggest that persistent DNA damage and cross-talk between TGF-β/IFNγ pathways contribute to a series of molecular events leading to cellular senescence and a segmental progeroid syndrome.

Topics: Cellular Senescence; Cryptorchidism; DNA Damage; Facies; Growth Disorders; Hand Deformities, Congenital; Humans; Intellectual Disability; Mutation; Smad4 Protein; Transforming Growth Factor beta

Topics: Cellular Senescence; Cryptorchidism; DNA Damage; Facies; Growth Disorders; Hand Deformities, Congenital; Humans; Intellectual Disability; Male; Mutation; Smad4 Protein; Syndrome; Transforming Growth Factor beta

Myhre syndrome is an increasingly diagnosed rare syndrome that is caused by one of two specific heterozygous gain-of-function pathogenic variants in SMAD4. The phenotype includes short stature, characteristic facial appearance, hearing loss, laryngotracheal stenosis, arthritis, skeletal abnormalities, learning and social challenges, distinctive cardiovascular defects, and a striking fibroproliferative response in the ear canals, airways, and serosal cavities (peritoneum, pleura, pericardium). Confirmation of the clinical diagnosis is usually prompted by the characteristic appearance with developmental delay and autistic-like behavior using targeted gene sequencing or by whole exome sequencing. We describe six patients (two not previously reported) with molecularly confirmed Myhre syndrome and neoplasia. Loss-of-function pathogenic variants in SMAD4 cause juvenile polyposis syndrome and we hypothesize that the gain-of-function pathogenic variants observed in Myhre syndrome may contribute to neoplasia in the patients reported herein. The frequency of neoplasia (9.8%, 6/61) in this series (two new, four reported patients) and endometrial cancer (8.8%, 3/34, mean age 40 years) in patients with Myhre syndrome, raises the possibility of cancer susceptibility in these patients. We alert clinicians to the possibility of detecting this syndrome when cancer screening panels are used. We propose that patients with Myhre syndrome are more susceptible to neoplasia, encourage increased awareness, and suggest enhanced clinical monitoring.

Topics: Adult; Cryptorchidism; Endometrial Neoplasms; Exome Sequencing; Facies; Female; Gain of Function Mutation; Growth Disorders; Hand Deformities, Congenital; Heterozygote; Humans; Intellectual Disability; Male; Middle Aged; Mutation; Neoplasms; Phenotype; Smad4 Protein; Transforming Growth Factor beta

Topics: Adolescent; Child; Colitis, Ulcerative; Crohn Disease; Enteral Nutrition; Female; Growth Disorders; Hematologic Tests; Humans; Male; Malnutrition; Remission Induction; Retrospective Studies; Transforming Growth Factor beta

Myhre syndrome (MS, MIM 139210) is a connective tissue disorder that presents with short stature, short hands and feet, facial dysmorphic features, muscle hypertrophy, thickened skin, and deafness. Recurrent missense mutations in SMAD4 encoding for a transducer mediating transforming growth factor β (TGF-β) signaling are responsible for MS. We found that MS fibroblasts showed increased SMAD4 protein levels, impaired matrix deposition, and altered expression of genes encoding matrix metalloproteinases and related inhibitors. Increased TGF-β signaling and progression of aortic root dilation in Marfan syndrome can be prevented by the antihypertensive drug losartan, a TGF-β antagonists and angiotensin-II type 1 receptor blocker. Herein, we showed that losartan normalizes metalloproteinase and related inhibitor transcript levels and corrects the extracellular matrix deposition defect in fibroblasts from MS patients. The results of this study may pave the way toward therapeutic applications of losartan in MS.

Topics: Adolescent; Adult; Child; Cryptorchidism; Extracellular Matrix; Facies; Female; Fibroblasts; Growth Disorders; Hand Deformities, Congenital; Humans; Hypertrophy; Intellectual Disability; Joint Diseases; Losartan; Metalloendopeptidases; Microfibrils; Mutation; Phosphorylation; Signal Transduction; Smad2 Protein; Smad4 Protein; Transforming Growth Factor beta; Young Adult

Geleophysic dysplasia is an autosomal recessive disorder characterized by short stature, brachydactyly, thick skin and cardiac valvular anomalies often responsible for an early death. Studying six geleophysic dysplasia families, we first mapped the underlying gene to chromosome 9q34.2 and identified five distinct nonsense and missense mutations in ADAMTSL2 (a disintegrin and metalloproteinase with thrombospondin repeats-like 2), which encodes a secreted glycoprotein of unknown function. Functional studies in HEK293 cells showed that ADAMTSL2 mutations lead to reduced secretion of the mutated proteins, possibly owing to the misfolding of ADAMTSL2. A yeast two-hybrid screen showed that ADAMTSL2 interacts with latent TGF-beta-binding protein 1. In addition, we observed a significant increase in total and active TGF-beta in the culture medium as well as nuclear localization of phosphorylated SMAD2 in fibroblasts from individuals with geleophysic dysplasia. These data suggest that ADAMTSL2 mutations may lead to a dysregulation of TGF-beta signaling and may be the underlying mechanism of geleophysic dysplasia.

Topics: Abnormalities, Multiple; Biological Availability; Cell Line; Child; Child, Preschool; Extracellular Matrix Proteins; Growth Disorders; Hand Deformities, Congenital; Heart Defects, Congenital; Heart Valves; Humans; Mutation; Transforming Growth Factor beta

The effects of a low-casein diet fortified with methionine and threonine on renal cortical and glomerular transforming growth factor (TGF)-beta activity were studied in rats with nephritis induced by anti-rat kidney glomerular basement membrane antiserum. Both normal and nephritic rats were fed experimental diets for 10 days. An injection of nephrotoxic serum increased urinary protein excretion and renal TGF-beta activity. A methionine-threonine-supplemented 8.5% casein diet, compared with a basal 20% casein diet, decreased these two measurements without aggravating growth retardation in nephritic rats. These results suggest that aggravation and alleviation of symptoms incident to anti-GBM nephritis are relevant to elevation and reduction of TGF-beta activity, respectively. The results also suggest that amino acid-balanced low-protein diets would have beneficial effects on glomerulonephritis without causing severe protein malnutrition.

Topics: Animals; Caseins; Cell Line; Dietary Proteins; Eating; Food, Fortified; Growth Disorders; Humans; Kidney; Kidney Glomerulus; Male; Methionine; Mink; Nephritis; Rats; Rats, Wistar; Threonine; Transforming Growth Factor beta

Childhood pyelonephritis is a common cause of renal cortical scarring and hypoplastic kidneys. To understand the mechanisms underlying the cortical lesions, urinary tract infection was induced in three-week-old rats by an intravesical infusion of E. coli, type 06 K13 HL a rat nephropathogenic strain. Four days after infection, histopathological examination showed marked infiltration of leukocytes in the medullary tissue adjoining the calyces and pelvis. In the cortex, signs of inflammation were found only in the cortical zone adjacent to the pelvis. No cells indicative of inflammation were observed in other parts of the cortex. Immunohistochemistry for endogenous proliferating cell nuclear antigen (PCNA) demonstrated a marked decrease in immunoreactivity in proximal tubular (PT) cells. The mitotic response of PT cells, assessed by 3H-thymidine autoradiography, showed a highly significant decrease during the first four days after induction of the infection. Four days after infection, a transient increase in apoptotic cells was observed in cortical cells outside the inflammatory areas. No increase in apoptotic cells was detected in the cortex 10 days after infection. Only a few apoptotic cells were detected in the control kidneys. In conclusion, the data indicate that inhibition of cell proliferation and enhancement of apoptosis may contribute to the renal parenchymal loss after childhood pyelonephritis.

Topics: Animals; Animals, Newborn; Apoptosis; DNA; Female; Growth Disorders; Kidney Cortex; Proliferating Cell Nuclear Antigen; Pyelonephritis; Rats; Rats, Sprague-Dawley; Transforming Growth Factor beta