Characterization of mammalian synemin, an intermediate filament protein present in all four classes of muscle cells and some neuroglial cells: co-localization and interaction with type III intermediate filament proteins and keratins

2003 ◽  
Vol 313 (2) ◽  
pp. 195-207 ◽  
Author(s):  
Yoshiaki Hirako ◽  
Hisashi Yamakawa ◽  
Yuki Tsujimura ◽  
Yuji Nishizawa ◽  
Masayo Okumura ◽  
...  
Keyword(s):  
Intermediate Filament ◽  
Muscle Cells ◽  
Intermediate Filament Protein ◽  
Intermediate Filament Proteins ◽  
Type Iii ◽  
Filament Protein

Identification of two N-terminal non-alpha-helical domain motifs important in the assembly of glial fibrillary acidic protein

1994 ◽  
Vol 107 (7) ◽  
pp. 1935-1948 ◽  
Author(s):  
J.E. Ralton ◽  
X. Lu ◽  
A.M. Hutcheson ◽  
R.A. Quinlan
Keyword(s):  
Intermediate Filament ◽  
Consensus Sequence ◽  
Intermediate Filament Protein ◽  
Intermediate Filament Proteins ◽  
Type Iii ◽  
Conserved Sequence ◽  
Terminal Domain ◽  
Filament Assembly ◽  
Arginine Residues ◽  
Filament Protein

The non-alpha-helical N-terminal domain of intermediate filament proteins plays a key role in filament assembly. Previous studies have identified a nonapeptide motif, SSYRRIFGG, in the non-alpha-helical N-terminal domain of vimentin that is required for assembly. This motif is also found in desmin, peripherin and the type IV intermediate filament proteins. GFAP is the only type III intermediate filament protein in which this motif is not readily identified. This study has identified two motifs in the non-alpha-helical N-terminal domain of mouse GFAP that play important roles in GFAP assembly. One motif is located at the very N terminus and has the consensus sequence, MERRRITS-ARRSY. It has some characteristics in common with the vimentin nonapeptide motif, SSYRRIFGG, including its location in the non-alpha-helical N-terminal domain and a concentration of arginine residues. Unlike the vimentin motif in which even conserved sequence changes affect filament assembly, the GFAP consensus sequence, MERRRITS-ARRSY, can be replaced by a completely unrelated sequence; namely, the heptapeptide, MVRANKR, derived from the lambda cII protein. When fused to GFAP sequences with sequential deletions of the N-terminal domain, the lambda cII heptapeptide was used to help identify a second motif, termed the RP-box, which is located just upstream of the GFAP alpha-helical rod domain. This RP-box affected the efficiency of filament assembly as well as protein-protein interactions in the filament, as shown by sedimentation assays and electron microscopy. These results are supported by previous data, which showed that the dramatic reorganization of GFAP within cells was due to phosphorylation-dephosphorylation of a site located in this RP-box. The results in this study suggest the RP-box motif to be a key modulator in the mechanism of GFAP assembly, and support a role for this motif in both the nucleation and elongation phases of filament assembly. The RP-box motif in GFAP has the consensus sequence, RLSL-RM-PP. Sequences similar to the GFAP RP-box motif are also to be found in vimentin, desmin and peripherin. Like GFAP, these include phosphorylation and proteolysis sites and are adjacent to the start of the central alpha-helical rod domain, suggesting that this motif of general importance to type III intermediate filament protein assembly.

A cDNA from Drosophila melanogaster encodes a lamin C-like intermediate filament protein

1993 ◽  
Vol 104 (4) ◽  
pp. 1263-1272 ◽  
Author(s):  
C.A. Bossie ◽  
M.M. Sanders
Keyword(s):  
Drosophila Melanogaster ◽  
Intermediate Filament ◽  
Blot Analysis ◽  
Polytene Chromosomes ◽  
Intermediate Filament Protein ◽  
Chromosome 2 ◽  
Cross Hybridization ◽  
Intermediate Filament Proteins ◽  
Nuclear Lamins ◽  
Filament Protein

A novel intermediate filament cDNA, pG-IF, has been isolated from a Drosophila melanogaster embryonic expression library screened with a polyclonal antiserum produced against a 46 kDa cytoskeletal protein isolated from Kc cells. This 46 kDa protein is known to be immunologically related to vertebrate intermediate filament proteins. The screen resulted in the isolation of four different cDNA groups. Of these, one has been identified as the previously characterized Drosophila nuclear lamin cDNA, Dm0, and a second, pG-IF, demonstrates homology to Dm0 by cross hybridization on Southern blots. DNA sequence analysis reveals that pG-IF encodes a newly identified intermediate filament protein in Drosophila. Its nucleotide sequence is highly homologous to nuclear lamins with lower homology to cytoplasmic intermediate filament proteins. pG-IF predicts a protein of 621 amino acids with a predicted molecular mass of 69,855 daltons. In vitro transcription and translation of pG-IF yielded a protein with a SDS-PAGE estimated molecular weight of approximately 70 kDa. It contains sequence principles characteristic of class V intermediate filament proteins. Its near neutral pI (6.83) and the lack of a terminal CaaX motif suggests that it may represent a lamin C subtype in Drosophila. In situ hybridization to polytene chromosomes detects one band of hybridization on the right arm of chromosome 2 at or near 51A. This in conjunction with Southern blot analysis of various genomic digests suggests one or more closely placed genes while Northern blot analysis detects two messages in Kc cells.

scholarly journals Identification of the intermediate filament protein synemin/SYNM as a target of myocardin family coactivators

2019 ◽  
Vol 317 (6) ◽  
pp. C1128-C1142 ◽  
Author(s):  
Karl Swärd ◽  
Katarzyna K. Krawczyk ◽  
Björn Morén ◽  
Baoyi Zhu ◽  
Ljubica Matic ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Intermediate Filament ◽  
Protein Level ◽  
Time Course ◽  
Target Genes ◽  
Serum Response Factor ◽  
Proximal Promoter ◽  
Intermediate Filament Protein ◽  
Intermediate Filament Proteins ◽  
Filament Protein

Myocardin (MYOCD) is a critical regulator of smooth muscle cell (SMC) differentiation, but its transcriptional targets remain to be exhaustively characterized, especially at the protein level. Here we leveraged human RNA and protein expression data to identify novel potential MYOCD targets. Using correlation analyses we found several targets that we could confirm at the protein level, including SORBS1, SLMAP, SYNM, and MCAM. We focused on SYNM, which encodes the intermediate filament protein synemin. SYNM rivalled smooth muscle myosin ( MYH11) for SMC specificity and was controlled at the mRNA and protein levels by all myocardin-related transcription factors (MRTFs: MYOCD, MRTF-A/MKL1, and MRTF-B/MKL2). MRTF activity is regulated by the ratio of filamentous to globular actin, and SYNM was accordingly reduced by interventions that depolymerize actin, such as latrunculin treatment and overexpression of constitutively active cofilin. Many MRTF target genes depend on serum response factor (SRF), but SYNM lacked SRF-binding motifs in its proximal promoter, which was not directly regulated by MYOCD. Furthermore, SYNM resisted SRF silencing, yet the time course of induction closely paralleled that of the SRF-dependent target gene ACTA2. SYNM was repressed by the ternary complex factor (TCF) FLI1 and was increased in mouse embryonic fibroblasts lacking three classical TCFs (ELK1, ELK3, and ELK4). Imaging showed colocalization of SYNM with the intermediate filament proteins desmin and vimentin, and MRTF-A/MKL1 increased SYNM-containing intermediate filaments in SMCs. These studies identify SYNM as a novel SRF-independent target of myocardin that is abundantly expressed in all SMCs.

scholarly journals Terminal web and vesicle trafficking proteins mediate nematode single-cell tubulogenesis

2020 ◽  
Vol 219 (11) ◽  
Author(s):  
Zhe Yang ◽  
Brendan C. Mattingly ◽  
David H. Hall ◽  
Brian D. Ackley ◽  
Matthew Buechner
Keyword(s):  
Intermediate Filament ◽  
Vesicular Transport ◽  
Intermediate Filament Protein ◽  
Endosomal Trafficking ◽  
Apical Surface ◽  
Intermediate Filament Proteins ◽  
Luminal Membrane ◽  
Terminal Web ◽  
Canal Cell ◽  
Filament Protein

Single-celled tubules represent a complicated structure that forms during development, requiring extension of a narrow cytoplasm surrounding a lumen exerting osmotic pressure that can burst the luminal membrane. Genetic studies on the excretory canal cell of Caenorhabditis elegans have revealed many proteins that regulate the cytoskeleton, vesicular transport, and physiology of the narrow canals. Here, we show that βH-spectrin regulates the placement of intermediate filament proteins forming a terminal web around the lumen, and that the terminal web in turn retains a highly conserved protein (EXC-9/CRIP1) that regulates apical endosomal trafficking. EXC-1/IRG, the binding partner of EXC-9, is also localized to the apical membrane and affects apical actin placement and RAB-8–mediated vesicular transport. The results suggest that an intermediate filament protein acts in a novel pathway to direct the traffic of vesicles to locations of lengthening apical surface during single-celled tubule development.

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