scholarly journals Evidence for Four Cytoplasmic Dynein Heavy Chain Isoforms in Rat Testis

1998 ◽  
Vol 9 (2) ◽  
pp. 237-247 ◽  
Author(s):  
Peggy S. Criswell ◽  
David J. Asai

Recent studies have revealed the expression of multiple putative cytoplasmic dynein heavy chain (DHC) genes in several organisms, with each gene encoding a separate protein isoform. This finding is consistent with the hypothesis that different isoforms do different things, as is the case for the axonemal dyneins. Furthermore, the large number of tasks ascribed to cytoplasmic dynein suggests that there may be additional isoforms not yet identified. Two of the mammalian cytoplasmic dynein heavy chains are DHC1a and DHC1b. DHC1a is conventional cytoplasmic dynein and is found in all organisms examined. DHC1b is expressed in organisms that have multiple dyneins, and has been implicated in the intracellular trafficking of molecules in unciliated and ciliated cells. In the present study, we examined the DHC1b protein from rat testis. Testis cytoplasmic dynein contains a large amount of dynein heavy chain reactive with an antibody raised against a peptide sequence of rat DHC1b. The testis anti-DHC1b immunoreactive protein is slightly smaller than testis DHC1a, as assessed by SDS-PAGE. In Northern blots, the DHC1b mRNA is smaller than the DHC1a mRNA. In sucrose gradients made in low ionic strength, DHC1a sedimented at approximately 20S, and the anti-1b immunoreactive heavy chains sedimented in a broad band centered at approximately 14S. The V1-photolysis reaction of individual sucrose gradient fractions revealed three distinct patterns of photolysis, suggesting that there are at least three separate 1b-like heavy chain isoforms in testis. Using a high-stringency Western blotting protocol, the anti-1b antibody and the anti-DHC2 antibody recognized the same heavy chain and specifically bound to one of the three 1b-like heavy chains. We conclude that rat testis contains three 1b-like dynein heavy chains, and one of these is the product of the DHC1b/DHC2 gene previously identified.

1994 ◽  
Vol 107 (3) ◽  
pp. 497-506 ◽  
Author(s):  
C.G. Wilkerson ◽  
S.M. King ◽  
G.B. Witman

We report here the complete sequence of the gamma dynein heavy chain of the outer arm of the Chlamydomonas flagellum, and partial sequences for six other dynein heavy chains. The gamma dynein heavy chain sequence contains four P-loop motifs, one of which is the likely hydrolytic site based on its position relative to a previously mapped epitope. Comparison with available cytoplasmic and flagellar dynein heavy chain sequences reveals regions that are highly conserved in all dynein heavy chains sequenced to date, regions that are conserved only among axonemal dynein heavy chains, and regions that are unique to individual dynein heavy chains. The presumed hydrolytic site is absolutely conserved among dyneins, two other P loops are highly conserved among cytoplasmic dynein heavy chains but not in axonemal dynein heavy chains, and the fourth P loop is invariant in axonemal dynein heavy chains but not in cytoplasmic dynein. One region that is very highly conserved in all dynein heavy chains is similar to a portion of the ATP-sensitive microtubule-binding domain of kinesin. Two other regions present in all dynein heavy chains are predicted to have high alpha-helical content and have a high probability of forming coiled-coil structures. Overall, the central one-third of the gamma dynein heavy chain is most conserved whereas the N-terminal one-third is least conserved; the fact that the latter region is divergent between the cytoplasmic dynein heavy chain and two different axonemal dynein heavy chains suggests that it is involved in chain-specific functions.


2019 ◽  
Vol 30 (15) ◽  
pp. 1834-1845 ◽  
Author(s):  
Ramila S. Patel-King ◽  
Miho Sakato-Antoku ◽  
Maya Yankova ◽  
Stephen M. King

WDR92 associates with a prefoldin-like cochaperone complex and known dynein assembly factors. WDR92 has been very highly conserved and has a phylogenetic signature consistent with it playing a role in motile ciliary assembly or activity. Knockdown of WDR92 expression in planaria resulted in ciliary loss, reduced beat frequency and dyskinetic motion of the remaining ventral cilia. We have now identified a Chlamydomonas wdr92 mutant that encodes a protein missing the last four WD repeats. The wdr92-1 mutant builds only ∼0.7-μm cilia lacking both inner and outer dynein arms, but with intact doublet microtubules and central pair. When cytoplasmic extracts prepared by freeze/thaw from a control strain were fractionated by gel filtration, outer arm dynein components were present in several distinct high molecular weight complexes. In contrast, wdr92-1 extracts almost completely lacked all three outer arm heavy chains, while the IFT dynein heavy chain was present in normal amounts. A wdr92-1 tpg1-2 double mutant builds ∼7-μm immotile flaccid cilia that completely lack dynein arms. These data indicate that WDR92 is a key assembly factor specifically required for the stability of axonemal dynein heavy chains in cytoplasm and suggest that cytoplasmic/IFT dynein heavy chains use a distinct folding pathway.


1996 ◽  
Vol 7 (1) ◽  
pp. 71-79 ◽  
Author(s):  
K L Andrews ◽  
P Nettesheim ◽  
D J Asai ◽  
L E Ostrowski

Axonemal dyneins are molecular motors that drive the beating of cilia and flagella. We report here the identification and partial cloning of seven unique axonemal dynein heavy chains from rat tracheal epithelial (RTE) cells. Combinations of axonemal-specific and degenerate primers to conserved regions around the catalytic site of dynein heavy chains were used to obtain cDNA fragments of rat dynein heavy chains. Southern analysis indicates that these are single copy genes, with one possible exception, and Northern analysis of RNA from RTE cells shows a transcript of approximately 15 kb for each gene. Expression of these genes was restricted to tissues containing axonemes (trachea, testis, and brain). A time course analysis during ciliated cell differentiation of RTE cells in culture demonstrated that the expression of axonemal dynein heavy chains correlated with the development of ciliated cells, while cytoplasmic dynein heavy chain expression remained constant. In addition, factors that regulate the development of ciliated cells in culture regulated the expression of axonemal dynein heavy chains in a parallel fashion. These are the first mammalian dynein heavy chain genes shown to be expressed specifically in axonemal tissues. Identification of the mechanisms that regulate the cell-specific expression of these axonemal dynein heavy chains will further our understanding of the process of ciliated cell differentiation.


1995 ◽  
Vol 6 (6) ◽  
pp. 697-711 ◽  
Author(s):  
M LeDizet ◽  
G Piperno

We show here that I2 and I3 inner dynein arm heavy chains of Chlamydomonas axonemes are resolved into two classes: one class associated with the protein p28 and the other associated with the protein caltractin/centrin. We have determined the nucleotide sequence of the gene encoding p28, a light chain that, together with actin and caltractin/centrin, is associated with inner dynein arms I2 and I3 of Chlamydomonas axonemes. p28 is a novel protein with affinity for a subset of the inner dynein arm heavy chains, but with no apparent significant homologies to tubulin- or actin-binding proteins. An antiserum specific for p28 showed that p28 is present along the entire axoneme. The same antiserum coimmunoprecipitated p28, actin, and dynein heavy chains 2' and 2. In contrast, an anti-caltractin/centrin antiserum coimmunoprecipitated caltractin/centrin, actin, and the heavy chains 2, 3, and 3'. It is likely that the dynein heavy chain 2 associated with p28, referred to as 2A, is a different polypeptide from dynein heavy chain 2 bound to caltractin/centrin, referred to as 2B. The complex formed by heavy chain 2B, actin, and caltractin/centrin is preferentially extracted by exposure to Nonidet P-40 and is missing in mutants lacking components 1 and 2 of the dynein regulatory complex.


1999 ◽  
Vol 10 (3) ◽  
pp. 771-784 ◽  
Author(s):  
Seungwon Lee ◽  
Julie C. Wisniewski ◽  
William L. Dentler ◽  
David J. Asai

In many organisms, there are multiple isoforms of cytoplasmic dynein heavy chains, and division of labor among the isoforms would provide a mechanism to regulate dynein function. The targeted disruption of somatic genes in Tetrahymena thermophilapresents the opportunity to determine the contributions of individual dynein isoforms in a single cell that expresses multiple dynein heavy chain genes. Substantial portions of twoTetrahymena cytoplasmic dynein heavy chain genes were cloned, and their motor domains were sequenced. Tetrahymena DYH1 encodes the ubiquitous cytoplasmic dynein Dyh1, andDYH2 encodes a second cytoplasmic dynein isoform, Dyh2. The disruption of DYH1, but not DYH2, resulted in cells with two detectable defects: 1) phagocytic activity was inhibited, and 2) the cells failed to distribute their chromosomes correctly during micronuclear mitosis. In contrast, the disruption of DYH2 resulted in a loss of regulation of cell size and cell shape and in the apparent inability of the cells to repair their cortical cytoskeletons. We conclude that the two dyneins perform separate tasks in Tetrahymena.


1994 ◽  
Vol 107 (3) ◽  
pp. 635-644 ◽  
Author(s):  
D.R. Mitchell ◽  
K.S. Brown

We have sequenced genomic clones spanning the complete coding region of one heavy chain (beta) and the catalytic domain of a second (alpha) of the Chlamydomonas reinhardtii flagellar outer arm dynein ATPase. The beta heavy chain gene (ODA-4 locus) spans 20 kb, is divided into at least 30 exons, and encodes a predicted 520 kDa protein. Comparison with sea urchin beta dynein sequences reveals homology that extends throughout both proteins. Over the most conserved central catalytic region, the Chlamydomonas alpha and beta chains are equally divergent from the sea urchin beta chain (64% and 65% similarity, respectively), whereas the Chlamydomonas gamma chain is more divergent from urchin beta (54% similarity). The four glycine-rich loops identified as potential nucleotide-binding sites in other dynein heavy chains are also present in Chlamydomonas alpha and beta dyneins. Two of these four nucleotide-binding motifs are highly conserved among flagellar dyneins, but only the motif previously identified as the catalytic site in sea urchin dynein is highly conserved between flagellar and cytoplasmic dynein heavy chains. Predictions of secondary structure suggest that all dynein heavy chains possess three large domains, with the four nucleotide-binding consensus sequences located in a central 185 kDa domain that is bounded on both sides by regions that form multiple, short alpha-helical coiled-coils.


1995 ◽  
Vol 6 (11) ◽  
pp. 1549-1562 ◽  
Author(s):  
K A Kandl ◽  
J D Forney ◽  
D J Asai

The genes encoding two Paramecium dynein heavy chains, DHC-6 and DHC-8, have been cloned and sequenced. Sequence-specific antibodies demonstrate that DHC-6 encodes ciliary outer arm beta-chain and DHC-8 encodes a cytoplasmic dynein heavy chain. Therefore, this study is the first opportunity to compare the primary structures and expression of two heavy chains representing the two functional classes of dynein expressed in the same cell. Deciliation of paramecia results in the accumulation of mRNA from DHC-6, but not DHC-8. Nuclear run-on transcription experiments demonstrate that this increase in the steady state concentration of DHC-6 mRNA is a consequence of a rapid induction of transcription in response to deciliation. This is the first demonstration that dynein, like other axonemal components, is transcriptionally regulated during reciliation. Analyses of the sequences of the two Paramecium dyneins and the dynein heavy chains from other organisms indicate that the heavy chain can be divided into three regions: 1) the sequence of the central catalytic domain is conserved among all dyneins; 2) the tail domain sequence, consisting of the N-terminal 1200 residues, differentiates between axonemal and cytoplasmic dyneins; and 3) the N-terminal 200 residues are the most divergent and appear to classify the isoforms. The organization of the heavy chain predicts that the variable tail domain may be sufficient to target the dynein to the appropriate place in the cell.


1997 ◽  
Vol 8 (4) ◽  
pp. 607-620 ◽  
Author(s):  
S H Myster ◽  
J A Knott ◽  
E O'Toole ◽  
M E Porter

Multiple members of the dynein heavy chain (Dhc) gene family have been recovered in several organisms, but the relationships between these sequences and the Dhc isoforms that they encode are largely unknown. To identify Dhc loci and determine the specific functions of the individual Dhc isoforms, we have screened a collection of motility mutants generated by insertional mutagenesis in Chlamydomonas. In this report, we characterize one strain, pf9-3, in which the insertion event was accompanied by a deletion of approximately 13 kb of genomic DNA within the transcription unit of the Dhc1 gene. Northern blot analysis confirms that pf9-3 is a null mutation. Biochemical and structural studies of isolated axonemes demonstrate that the pf9-3 mutant fails to assemble the I1 inner arm complex, a two-headed dynein isoform composed of two Dhcs (1 alpha and 1 beta) and three intermediate chains. To determine if the Dhc1 gene product corresponds to one of the Dhcs of the I1 complex, antibodies were generated against a Dhc1-specific peptide sequence. Immunoblot analysis reveals that the Dhc1 gene encodes the 1 alpha Dhc subunit. These studies thus, identify the first inner arm Dhc locus to be described in any organism and further demonstrate that the 1 alpha Dhc subunit plays an essential role in the assembly of the I1 inner arm complex.


1995 ◽  
Vol 108 (5) ◽  
pp. 1883-1893 ◽  
Author(s):  
Y. Tanaka ◽  
Z. Zhang ◽  
N. Hirokawa

RT-PCR cloning was performed to find unknown members of the dynein superfamily expressed in rat brain. Six kinds of degenerate primers designed for the dynein catalytic domain consensuses were used for extensive PCR amplifications. We have sequenced 550 plasmid clones which turned out to include 13 kinds of new dynein-like sequences (DLP1-8, 9A/B, 10–12) and cytoplasmic dynein heavy chain. In these clones, alternative splicing was detected for a 105 nt-domain containing the CFDEFNRI consensus just downstream of the most N-terminal P-loop (DLP9A and 9B). By using these obtained sequences, initial hybridization studies were performed. Genomic Southern blotting showed each sequence corresponds to a single copy of the gene, while northern blotting of adult brain presented more than one band for some subtypes. We further accomplished molecular evolutionary analysis to recognize their phylogenetic origins for the axonemal and non-axonemal (cytoplasmic) functions. Different methods (UPGMA, NJ and MP) presented well coincident phylogenetic trees from 44 partial amino acid sequences of dynein heavy chain from various eukaryotes. The trunk for all the cytoplasmic dynein heavy chain homologues diverged directly from the root of the phylogenetic tree, suggesting that the first dynein gene duplication defined two distinct functions as respective subfamilies. Of particular interest, we found a duplication event of the cytoplasmic dynein heavy chain gene giving rise to another subtype, DLP4, located between the divergence of yeast and that of Dictyostelium. Such evolutionary topology builds up an inceptive hypothesis that there are at least two non-axonemal dynein heavy chains in mammals.


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