scholarly journals The TGFβ type I receptor TGFβRI functions as an inhibitor of BMP signaling in cartilage

2019 ◽  
Vol 116 (31) ◽  
pp. 15570-15579 ◽  
Author(s):  
Weiguang Wang ◽  
Hyelim Chun ◽  
Jongseung Baek ◽  
Joshua Elyahu Sadik ◽  
Anna Shirazyan ◽  
...  
Keyword(s):  
Growth Plate ◽  
Bmp Signaling ◽  
Type I ◽  
Type Ii ◽  
Tgfβ Signaling ◽  
Major Function ◽  
High Affinity ◽  
Bmp Receptor ◽  
Tgfβ Receptor ◽  
Intracellular Mediators

The type I TGFβ receptor TGFβRI (encoded by Tgfbr1) was ablated in cartilage. The resulting Tgfbr1Col2 mice exhibited lethal chondrodysplasia. Similar defects were not seen in mice lacking the type II TGFβ receptor or SMADs 2 and 3, the intracellular mediators of canonical TGFβ signaling. However, we detected elevated BMP activity in Tgfbr1Col2 mice. As previous studies showed that TGFβRI can physically interact with ACVRL1, a type I BMP receptor, we generated cartilage-specific Acvrl1 (Acvrl1Col2) and Acvrl1/Tgfbr1 (Acvrl1/Tgfbr1Col2) knockouts. Loss of ACVRL1 alone had no effect, but Acvrl1/Tgfbr1Col2 mice exhibited a striking reversal of the chondrodysplasia seen in Tgfbr1Col2 mice. Loss of TGFβRI led to a redistribution of the type II receptor ACTRIIB into ACVRL1/ACTRIIB complexes, which have high affinity for BMP9. Although BMP9 is not produced in cartilage, we detected BMP9 in the growth plate, most likely derived from the circulation. These findings demonstrate that the major function of TGFβRI in cartilage is not to transduce TGFβ signaling, but rather to antagonize BMP signaling mediated by ACVRL1.

scholarly journals Specification of BMP Signaling

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1579 ◽  
Author(s):  
Joachim Nickel ◽  
Thomas D. Mueller
Keyword(s):  
Growth Factors ◽  
Transforming Growth Factor ◽  
Bmp Signaling ◽  
Current View ◽  
Receptor Subtypes ◽  
Type I ◽  
Dependent Manner ◽  
Type Ii ◽  
Tgfβ Signaling ◽  
Receptor Complexes

Bone Morphogenetic Proteins (BMPs) together with the Growth and Differentiation Factors (GDFs) form the largest subgroup of the Transforming Growth Factor (TGF)β family and represent secreted growth factors, which play an essential role in many aspects of cell communication in higher organisms. As morphogens they exert crucial functions during embryonal development, but are also involved in tissue homeostasis and regeneration in the adult organism. Their involvement in maintenance and repair processes of various tissues and organs made these growth factors highly interesting targets for novel pharmaceutical applications in regenerative medicine. A hallmark of the TGFβ protein family is that all of the more than 30 growth factors identified to date signal by binding and hetero-oligomerization of a very limited set of transmembrane serine-threonine kinase receptors, which can be classified into two subgroups termed type I and type II. Only seven type I and five type II receptors exist for all 30plus TGFβ members suggesting a pronounced ligand-receptor promiscuity. Indeed, many TGFβ ligands can bind the same type I or type II receptor and a particular receptor of either subtype can usually interact with and bind various TGFβ ligands. The possible consequence of this ligand-receptor promiscuity is further aggravated by the finding that canonical TGFβ signaling of all family members seemingly results in the activation of just two distinct signaling pathways, that is either SMAD2/3 or SMAD1/5/8 activation. While this would implicate that different ligands can assemble seemingly identical receptor complexes that activate just either one of two distinct pathways, in vitro and in vivo analyses show that the different TGFβ members exert quite distinct biological functions with high specificity. This discrepancy indicates that our current view of TGFβ signaling initiation just by hetero-oligomerization of two receptor subtypes and transduction via two main pathways in an on-off switch manner is too simplified. Hence, the signals generated by the various TGFβ members are either quantitatively interpreted using the subtle differences in their receptor-binding properties leading to ligand-specific modulation of the downstream signaling cascade or additional components participating in the signaling activation complex allow diversification of the encoded signal in a ligand-dependent manner at all cellular levels. In this review we focus on signal specification of TGFβ members, particularly of BMPs and GDFs addressing the role of binding affinities, specificities, and kinetics of individual ligand-receptor interactions for the assembly of specific receptor complexes with potentially distinct signaling properties.

scholarly journals Ultrastructural localization of the C-propeptide released from type II procollagen in fetal bovine growth plate cartilage.

1996 ◽  
Vol 44 (5) ◽  
pp. 433-443 ◽  
Author(s):  
E R Lee ◽  
C E Smith ◽  
R Poole
Keyword(s):  
Growth Plate ◽  
Ultrastructural Localization ◽  
Collagen Fibrils ◽  
Type Ii ◽  
Guanidinium Hydrochloride ◽  
High Affinity ◽  
Sds Page ◽  
The Matrix ◽  
Fetal Bovine ◽  
Mineralized Matrix

We used immunochemical and immunoelectron gold techniques to determine whether the C-propeptide previously identified in the matrix of endochondral cartilage (CPII) was still a part of the Type 11 procollagen molecule or had been released from it. Guanidinium hydrochloride extraction, followed by SDS-PAGE and Western blotting techniques and immunoelectron localization, revealed that predominantly only the released form (hereafter referred to as released CPII) was detected. The ultrastructural distribution of this CPII was examined with affinity-purified antibodies and with immunogold or immunoperoxidase localization techniques in the presence or absence of embedding resins. These methods yielded similar results. Although no significant amount of this CPII was retained in the matrix after guanidinium hydrochloride extraction, it was present in two recognizable sites under normal conditions, i.e., locally concentrated in a random association with collagen fibrils in the nonmineralized matrix and mainly concentrated in interfibrillar mineralizing sites in the mineralized matrix. These results suggest that the C-propeptide that has been released from Type II procollagen associates with collagen fibrils and then preferentially associates with mineralizing sites when these form in the endochondral cartilage. The significance of this preference for mineral is not known but may have something to do with its high affinity for hydroxyapatite.

scholarly journals Tetraspanins TSP-12 and TSP-14 function redundantly to regulate the trafficking of the type II BMP receptor in Caenorhabditis elegans

2020 ◽  
Vol 117 (6) ◽  
pp. 2968-2977
Author(s):  
Zhiyu Liu ◽  
Herong Shi ◽  
Anthony K. Nzessi ◽  
Anne Norris ◽  
Barth D. Grant ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Surface ◽  
Molecular Mechanisms ◽  
Transmembrane Protein ◽  
Expression Patterns ◽  
Bmp Signaling ◽  
Type I ◽  
Type Ii ◽  
Bmp Receptors

Tetraspanins are a unique family of 4-pass transmembrane proteins that play important roles in a variety of cell biological processes. We have previously shown that 2 paralogous tetraspanins in Caenorhabditis elegans, TSP-12 and TSP-14, function redundantly to promote bone morphogenetic protein (BMP) signaling. The underlying molecular mechanisms, however, are not fully understood. In this study, we examined the expression and subcellular localization patterns of endogenously tagged TSP-12 and TSP-14 proteins. We found that TSP-12 and TSP-14 share overlapping expression patterns in multiple cell types, and that both proteins are localized on the cell surface and in various types of endosomes, including early, late, and recycling endosomes. Animals lacking both TSP-12 and TSP-14 exhibit reduced cell-surface levels of the BMP type II receptor DAF-4/BMPRII, along with impaired endosome morphology and mislocalization of DAF-4/BMPRII to late endosomes and lysosomes. These findings indicate that TSP-12 and TSP-14 are required for the recycling of DAF-4/BMPRII. Together with previous findings that the type I receptor SMA-6 is recycled via the retromer complex, our work demonstrates the involvement of distinct recycling pathways for the type I and type II BMP receptors and highlights the importance of tetraspanin-mediated intracellular trafficking in the regulation of BMP signaling in vivo. As TSP-12 and TSP-14 are conserved in mammals, our findings suggest that the mammalian TSP-12 and TSP-14 homologs may also function in regulating transmembrane protein recycling and BMP signaling.

scholarly journals Expression of a Truncated, Kinase-Defective TGF-β Type II Receptor in Mouse Skeletal Tissue Promotes Terminal Chondrocyte Differentiation and Osteoarthritis

1997 ◽  
Vol 139 (2) ◽  
pp. 541-552 ◽  
Author(s):  
Rosa Serra ◽  
Mahlon Johnson ◽  
Ellen H. Filvaroff ◽  
James LaBorde ◽  
Daniel M. Sheehan ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Transgenic Mice ◽  
Growth Plate ◽  
Dominant Negative Mutant ◽  
Type I ◽  
Type Ii ◽  
Type X Collagen ◽  
Skeletal Tissue ◽  
Hypertrophic Cartilage ◽  
Growth Plate Cartilage

Members of the TGF-β superfamily are important regulators of skeletal development. TGF-βs signal through heteromeric type I and type II receptor serine/threonine kinases. When over-expressed, a cytoplasmically truncated type II receptor can compete with the endogenous receptors for complex formation, thereby acting as a dominant-negative mutant (DNIIR). To determine the role of TGF-βs in the development and maintenance of the skeleton, we have generated transgenic mice (MT-DNIIR-4 and -27) that express the DNIIR in skeletal tissue. DNIIR mRNA expression was localized to the periosteum/perichondrium, syno-vium, and articular cartilage. Lower levels of DNIIR mRNA were detected in growth plate cartilage. Transgenic mice frequently showed bifurcation of the xiphoid process and sternum. They also developed progressive skeletal degeneration, resulting by 4 to 8 mo of age in kyphoscoliosis and stiff and torqued joints. The histology of affected joints strongly resembled human osteo-arthritis. The articular surface was replaced by bone or hypertrophic cartilage as judged by the expression of type X collagen, a marker of hypertrophic cartilage normally absent from articular cartilage. The synovium was hyperplastic, and cartilaginous metaplasia was observed in the joint space. We then tested the hypothesis that TGF-β is required for normal differentiation of cartilage in vivo. By 4 and 8 wk of age, the level of type X collagen was increased in growth plate cartilage of transgenic mice relative to wild-type controls. Less proteoglycan staining was detected in the growth plate and articular cartilage matrix of transgenic mice. Mice that express DNIIR in skeletal tissue also demonstrated increased Indian hedgehog (IHH) expression. IHH is a secreted protein that is expressed in chondrocytes that are committed to becoming hypertrophic. It is thought to be involved in a feedback loop that signals through the periosteum/ perichondrium to inhibit cartilage differentiation. The data suggest that TGF-β may be critical for multifaceted maintenance of synovial joints. Loss of responsiveness to TGF-β promotes chondrocyte terminal differentiation and results in development of degenerative joint disease resembling osteoarthritis in humans.

Pyruvate shuttle in muscle cells: high-affinity pyruvate transport sites insensitive to trans-lactate efflux

2003 ◽  
Vol 285 (6) ◽  
pp. E1196-E1204
Author(s):  
Raymond Mengual ◽  
Kaoukib el Abida ◽  
Nassima Mouaffak ◽  
Michel Rieu ◽  
Michele Beaudry
Keyword(s):  
High Capacity ◽  
Muscle Cells ◽  
Type I ◽  
Maximal Velocity ◽  
Type Ii ◽  
Lactate Shuttle ◽  
Transport Efficiency ◽  
High Affinity ◽  
High K ◽  
Transport Kinetic

The specificity of the transport mechanisms for pyruvate and lactate and their sensitivity to inhibitors were studied in L6 skeletal muscle cells. Trans- and cis-lactate effects on pyruvate transport kinetic parameters were examined. Pyruvate and lactate were transported by a multisite carrier system, i.e., by two families of sites, one with low affinity and high capacity (type I sites) and the other with high affinity and low capacity (type II). The multisite character of transport kinetics was not modified by either hydroxycinnamic acid (CIN) or p-chloromercuribenzylsulfonic acid (PCMBS), which exert different types of inhibition. The transport efficiency (TE) ratios of maximal velocity to the trans-activation dissociation constant ( Kt) showed that lactate and pyruvate were preferentially transported by types I and II sites, respectively. The cis-lactate effect was observed with high Ki values for both sites. The trans-lactate effect on pyruvate transport occurred only on type I sites and exhibited an asymmetric interaction pattern ( Kt of inward lactate > Kt of outward lactate). The inability of lactate to trans-stimulate type II sites suggests that intracellular lactate cannot recruit these sites. The high-affinity type II sites act as a specific pyruvate shuttle and constitute an essential relay for the intracellular lactate shuttle.

Abstract 547: TGFß Response Coupled to Stress Signaling by TGRL Lipolysis in Vascular Endothelial Cells

2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Hnin Aung ◽  
Larissa Eiselein ◽  
Michael W Lamé ◽  
Kit Ng ◽  
Dennis W Wilson ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Transcription Factor ◽  
Endothelial Cell ◽  
Map Kinases ◽  
Gene Array ◽  
Receptor Activation ◽  
Type I ◽  
Tgfβ Signaling ◽  
Tgfβ Receptor ◽  
Activating Transcription Factor

Elevation of circulating triglyceride-rich lipoproteins (TGRL) in the postprandial state is associated with increased endothelial cell inflammation and dysfunction potentially contributing to atherosclerosis. Previous studies from our laboratory showed that lipolysis products of TGRL induced endothelial cell barrier permeability, up-regulation of cytokines and adhesion molecules, and apoptosis. Gene array studies implicated the Stress Associated Protein Kinase and c-Jun N-terminal kinase (SAPK/JNK) pathway and identified the transcription factor activating transcription factor 3 (ATF3) as highly induced in this process. Additional studies demonstrated activation of second messengers for transforming growth factor beta (TGFβ) signaling (SMAD2/SMAD4) in response to lipolysis product treatment. In the present study, we asked whether TGFβ signaling was implicated in the induction of apoptosis by lipolysis products and whether there was a linkage between TGFβ receptor activation and pro-inflammatory responses. siRNA knockdown of ATF3 transcription abrogated both IL-8 and E-selectin up-regulation in lipolysis product-treated human aortic endothelial cells (HAEC). In addition, ATF3 knockdown prevented activation of caspase 3/7 and induction of p53, markers of apoptosis. Inhibition of the TGFβ Type I activin receptor-like kinase (ALK) receptors (ALKs 4, 5 and 7) by SB 431542 (10 μM) also inhibited inflammatory up-regulation, ATF3 induction and apoptosis. Both ATF3 knockdown and TGFβ receptor blockade prevented c-Jun phosphorylation, a co-activating transcription factor with ATF3 of AP-1 transcription sites. Our findings implicate TGFβ signaling in the inflammatory and apoptotic responses to TGRL lipolysis and suggest a complex interaction between TGFβ receptors and the SAPK subset of MAP Kinases.

XBMPRII, a novel Xenopus type II receptor mediating BMP signaling in embryonic tissues

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 431-442 ◽  
Author(s):  
A. Frisch ◽  
C.V. Wright
Keyword(s):  
Cell Fate ◽  
Organizer Region ◽  
Bmp Signaling ◽  
Dominant Negative ◽  
Mesoderm Induction ◽  
Type I ◽  
Type Ii ◽  
Common Component ◽  
Activin Signaling

Bone Morphogenetic Proteins (BMPs) are potent regulators of embryonic cell fate that are presumed to initiate signal transduction in recipient cells through multimeric, transmembrane, serine/threonine kinase complexes made up of type I and type II receptors. BMPRII was identified previously in mammals as the only type II receptor that binds BMPs, but not activin or TGFbeta, in vitro. We report the cloning and functional analysis in vivo of its Xenopus homolog, XBMPRII. XBMPRII is expressed maternally and zygotically in an initially unrestricted manner. Strikingly, XBMPRII transcripts then become restricted to the mesodermal precursors during gastrulation. Expression is lower in the dorsal organizer region, potentially providing a mechanism to suppress the actions of BMP4 on dorsally fated tissues. Similar to the results seen for a truncated type I BMP receptor (tBR), a dominant-negative form of XBMPRII (tBRII) can dorsalize ventral mesoderm, induce extensive secondary body axes, block mesoderm induction by BMP4 and directly neuralize ectoderm, strongly suggesting that XBMPRII mediates BMP signals in vivo. However, although both tBRII and tBR can induce partial secondary axes, marker analysis shows that tBRII-induced axes are more anteriorly extended. Additionally, coinjection of tBRII and tBR synergistically increases the incidence of secondary axis formation. A truncated activin type II receptor (deltaXAR1) is known to block both activin and BMP signaling in vivo. Here we show that such crossreactivity does not occur for tBRII, in that it does not affect activin signaling. Furthermore, our studies indicate that the full-length activin type II receptor (XAR1) overcomes a block in BMP4 signaling imposed by tBRII, implicating XAR1 as a common component of BMP and activin signaling pathways in vivo. These data implicate XBMPRII as a type II receptor with high selectivity for BMP signaling, and therefore as a critical mediator of the effects of BMPs as mesodermal patterning agents and suppressors of neural fate during embryogenesis.

scholarly journals Relative contributions of Na+-dependent phosphate co-transporters to phosphate transport in mouse kidney: RNase H-mediated hybrid depletion analysis

1997 ◽  
Vol 327 (3) ◽  
pp. 735-739 ◽  
Author(s):  
Ken-ichi MIYAMOTO ◽  
Hiroko SEGAWA ◽  
Kyoko MORITA ◽  
Tomoko NII ◽  
Sawako TATSUMI ◽  
...  
Keyword(s):  
Antisense Oligonucleotides ◽  
Xenopus Oocytes ◽  
Mouse Kidney ◽  
Rnase H ◽  
Transport Systems ◽  
Kidney Cortex ◽  
Type I ◽  
Type Ii ◽  
High Affinity ◽  
Pi Transport

Reabsorption of Pi in the proximal tubule of the kidney is an important determinant of Pi homoeostasis. At least three types (types I-III) of high-affinity Na+-dependent Pi co-transporters have been identified in mammalian kidneys. The relative roles of these three types of Na+/Pi co-transporters in Pi transport in mouse kidney cortex have now been investigated by RNase H-mediated hybrid depletion. Whereas isolated brush-border membrane vesicles showed the presence of two kinetically distinct Na+/Pi co-transport systems (high Km-low Vmax and low Km-high Vmax), Xenopus oocytes, microinjected with polyadenylated [poly(A)+] RNA from mouse kidney cortex, showed only the high-affinity Pi uptake system. Kidney poly(A)+ RNA was incubated in vitro with antisense oligonucleotides corresponding to Npt-1 (type I), NaPi -7 (type II) or Glvr-1 (type III) Na+/Pi co-transporter mRNAs, and then with RNase H. Injection of such treated RNA preparations into Xenopus oocytes revealed that an NaPi-7 antisense oligonucleotide that resulted in complete degradation of NaPi-7 mRNA (as revealed by Northern blot analysis), also induced complete inhibition of Pi uptake. Degradation of Npt-1 or Glvr-1 mRNAs induced by corresponding antisense oligonucleotides had no effect on Pi transport, which was subsequently measured in oocytes. These results indicate that the type II Na+/Pi co-transporter NaPi-7 mediated most Na+-dependent Pi transport in mouse kidney cortex.

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