Golomb M et al. (1989) International C. elegans Meeting "altered transcription patterns in the C elegans dauer larva."

Dalley BK, Golomb M

[International C. elegans Meeting, 1989]

Dalley BK et al. (1991) International C. elegans Meeting "mRNA TRANSCRIPTION IN C. ELEGANS DAUER LARVAE."

Golomb M, Dalley BK

[International C. elegans Meeting, 1991]

We have examined RNA polymerase II transcription in the dauer larva and during dauer recovery. Run-on transcription assays with isolated nuclei indicate that dauer larvae actively transcribe bulk mRNA, but at a sharply reduced rate (10-15%) relative to other stages. Northern analysis and run-on assays reveal a pattern distinct from actively growing stages. Transcription of several structural genes and of SLl RNA is reduced in dauer larvae. However, steady-state levels of hsp70 mRNA in dauer larvae are comparable to those in other stages, although hsp70 message is transcribed at a lower rate. Dauer larvae respond to heat shock (Snutch and Baillie (1983), Can. J. Biochem. Cell Biol. 61: 480-487). We have looked at induction of two heat shock messages, hsp70 (constitutively expressed but inducible to higher levels by heat shock), and hspl6 (expressed exclusively following heat shock). When dauer larvae are subjected to heat shock, levels of both heat shock messages are rapidly elevated. Thus, mRNAs can be initiated (and induced) in dauer larvae. Recovery of worms from the dauer stage is accompanied by an ordered temporal sequence of gene expression. Within 75 min after placement in food, or shortly after commitment, bulk mRNA transcription increases 2-fold. At this time, hsp70 mRNA begins to increase steadily, reaching levels 2- to 3-fold higher than in other stages and then dropping to constitutive levels by the 4th hour of recovery. Histone mRNA starts to increase by the 4th hour of recovery ( when feeding resumes), whereas myosin mRNA accumulates at 10 h (just before molt). We are interested in identifying genes expressed early in dauer recovery.

Rogalski TM et al. (1991) International C. elegans Meeting "GENETIC APPROACHES TO C. ELEGANS RNA POLYMERASE III."

Golomb M, Watson N, Lancy ED, Rogalski TM, Riddle DL, Albert PS

[International C. elegans Meeting, 1991]

RNA polymerase III (Rpo m) transcribes genes encoding SS and transfer RNA's. This enzyme and its associated factors have been studied extensively in other systems, but Rpo m function has not been studied genetically in a metazoan. Developmental regulation of Rpo m activity in C. elegans has been suggested by the molecular genetic analysis of nonsense suppressors (Kondo et al., J. Mol. Biol. 215:7-19, 1990). The gene for the largest subunit of Rpo m, rpc-l, has been cloned (Bird and Riddle, Mol. Cell. Biol. 9:4119-4130, 1989) and positioned on the physical map between unc44 and unc-24 on chromosome IV. The availability of cloned genes and an in vitro transcription system (Honda et al., Nucl. Acid Res. 14B:869-881, 1986) provides potential tools for a detailed analysis of Rpo III structure and function using mutants, if appropriate mutants can be identified. Two approaches to genetic analysis of rpc-l have been employed. The first approach utilized resistance to the fungal toxin, ct-amanitin. A unique strain with an extremely amanitin-resistant Rpo II (Rogalski et al., Genetics 126:889-898, 1990) was used as a parent to select even higher levels of resistance. One such mutation was mapped on chromosome IV, and preliminary nuclear run-on assays indicate that Rpo III is abnormally resistant to amanitin, in appropriate recombinants derived from this mutant strain. The mutant Rpo III transcribes SS RNA in the presence of 200 g/ml amanitin, whereas wild-type Rpo m is inhibited by 25 g/ml. These results suggest that the resistance mutation affects Rpo III, and it may be within the rpc-l gene. A second approach to rpc-l genetics utilized a collection of EMSinduced lethal mutations generated by Denise Clark. We mapped fourteen of her lethal mutations to the interval between unc44 and unc-24, a region estimated to contain approximately 30 essential genes. These lethal mutations are now being assigned to complementation groups. Lethal derivatives of the putative amanitin-resistant rpc-l allele will also be sought, and selected lethal strains will be injected with the cloned rpc-l gene in an effort to identify the genetic correlate to rpc-l by DNA transformation. Genetic, phenotypic, and biochemical analysis of these mutants may provide a useful entree into structure- function relationships in this important enzyme.

Tullis GE et al. (1987) International C. elegans Meeting "RNA polymerase II in mutant strains of C elegans and in dauer larvae."

Tullis GE, Golomb M, Dalley BK

[International C. elegans Meeting, 1987]

Rogalski TM et al. (1989) International C. elegans Meeting "a novel ama-1 allele that eliminates sensitivity of RNA polymerase II to alpha-amanitin."

Rogalski TM, Golomb M, Riddle DL

[International C. elegans Meeting, 1989]

Sanford TR et al. (1983) International C. elegans Meeting "RNA polymerase II from wild-type and amanitin-resistant strains of C elegans."

Sanford TR, Riddle DL, Golomb M

[International C. elegans Meeting, 1983]

Prenger JP et al. (1987) International C. elegans Meeting "mapping epitopes and functional domains on RNA polymerase II from C elegans."

Weinmann R, Prenger JP, Golomb M, Boettcher J

[International C. elegans Meeting, 1987]

Prenger JP et al. (1985) International C. elegans Meeting "monoclonal antibodies against RNA polymerase II from C elegans."

Tollefson A, Prenger JP, Golomb M, Bullerjahn AME

[International C. elegans Meeting, 1985]

Marisa Foehr et al. (2007) International Worm Meeting "Dorsoventral patterning of the postembryonic mesoderm requires both LIN-12/Notch and TGF-beta signaling."

Marisa Foehr, Jun Liu

[International Worm Meeting, 2007]

The C. elegans post-embryonic mesodermal lineage arises from a single precursor cell, the M mesoblast, which will diversify to generate distinct dorsal and ventral cell types. The dorsal daughter of M gives rise to a subset of body wall muscles and two non-muscle coelomocytes, whereas the ventral daughter of M gives rise to two sex myoblasts in addition to a subset of body wall muscles. Mutations in the C. elegans Schnurri homolog sma-9 cause ventralization of the M lineage. We have previously shown that SMA-9 antagonizes the Sma/Mab TGF-beta signaling pathway to promote dorsal M lineage fates (Foehr et al., 2006). Interestingly, loss-of-function mutations in the Notch receptor homolog lin-12 cause dorsalization of the M lineage (Greenwald et al., 1983), an exact opposite phenotype of sma-9 mutants. We have found that while LIN-12 protein is present in both the dorsal and ventral M lineage cells, the ligands for LIN-12, LAG-2 and APX-1, are asymmetrically localized in cells adjacent to ventral M-derived cells, and they function redundantly in promoting ventral M lineage fates. To investigate how LIN-12/Notch signaling interacts with SMA-9 and the Sma/Mab TGF-beta pathway in regulating M lineage patterning, we generated double and triple mutant combinations among lin-12, sma-9 and dbl-1 (the ligand for the Sma/Mab TGF-beta pathway) and examined their M lineage phenotypes. Our results suggest that the LIN-12/Notch pathway and the Sma/Mab TGF-beta pathway function independently in regulating dorsoventral patterning of the M lineage, with LIN-12/Notch required for ventral M lineage fates, and SMA-9 antagonism of TGF-beta signaling required for dorsal M lineage fates. Our work provides a model for how combined Notch and TGF-beta signaling regulates the developmental potential of two equipotent cells along the dorsoventral axis.

Nirav Amin et al. (2008) Development & Evolution Meeting "Systematic analysis of transcription factors important in C. elegans postembryonic mesodermal development"

Zach Via, Jun Liu, Nirav Amin

[Development & Evolution Meeting, 2008]

The C. elegans postembryonic mesodermal lineage, the M lineage, is a powerful model system to study mesodermal patterning and cell fate specification at single cell resolution. The M lineage arises from a single pluripotent cell, the M mesoblast, during embryogenesis. In hermaphrodites, the M cell undergoes a series of postembryonic cell divisions to produce 18 cells: 14 body wall muscles (BWMs), 2 coelomocytes (CCs), and 2 sex myoblasts (SMs). We and others have previously identified a handful of transcription factors important for the proper development of this lineage. In order to identify additional transcription factors that play a role in the M lineage, we have generated a feeding RNAi library that targets a majority of the predicted transcription factors encoded in the C. elegans genome and conducted an RNAi screen using cell type-specific GFP reporters in the M lineage. From this screen, we identified a novel set of 32 transcription factors that, upon RNAi knockdown, give reproducible phenotypes in the M lineage. Among these 32 transcription factors, four are important for patterning and fate specification of the early M lineage, while the rest appear to play a role in fate decisions in the SM lineage. We have primarily focused on let-381, which encodes a forkhead transcription factor that is essential for C. elegans development. let-381(RNAi) causes a dorsal to ventral fate transformation in the M lineage. We have found that a let-381::gfp translational fusion is expressed in the dorsal M lineage. Previous studies from our lab have shown that SMA-9, the Sma/Mab TGF-beta and LIN-12/Notch signaling pathways are involved in dorsal/ventral patterning of the M lineage. We are currently investigating the relationship between let-381 and these pathways.