mab-31 and the TGF-beta pathway act in the ray lineage to pattern C. elegans male sensory rays.
BACKGROUND
C. elegans TGF-beta-like Sma/Mab signaling pathway regulates both body size and sensory ray patterning. Most of the components in this pathway were initially identified by genetic screens based on the small body phenotype, and many of these mutants display sensory ray patterning defect. At the cellular level, little is known about how and where these components work although ray structural cell has been implicated as one of the targets. Based on the specific ray patterning abnormality, we aim to identify by RNAi approach additional components that function specifically in the ray lineage to elucidate the regulatory role of TGF-beta signaling in ray differentiation.


RESULTS
We report here the characterization of a new member of the Sma/Mab pathway, mab-31, recovered from a genome-wide RNAi screen. mab-31 mutants showed ray cell cluster patterning defect and mis-specification of the ray identity. mab-31 encodes a nuclear protein expressed in descendants of ray precursor cells impacting on the ray cell's clustering properties, orientation of cell division plane, and fusion of structural cells. Genetic experiments also establish its relationship with other Sma/Mab pathway components and transcription factors acting upstream and downstream of the signaling event.


CONCLUSIONS
mab-31 function is indispensable in Sma/Mab signal recipient cells during sensory rays specification. Both mab-31 and sma-6 are required in ray lineage at the late larval stages. They act upstream of C. elegans Pax-6 homolog and repress its function. These findings suggested mab-31 is a key factor that can integrate TFG-beta signals in male sensory ray lineage to define organ identity.
Wong
Yan-Fung
YF
Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Sheng
Qing
Q
Chung
Janet W L
JW
Chan
Jacky K F
JK
Chow
King L
KL
D000818:Animals; D017173:Caenorhabditis elegans / Q000033:anatomy & histology* / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D055106:Genome-Wide Association Study; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D009687:Nuclear Proteins; D011956:Receptors, Cell Surface; C117510:SMA-6 protein, C elegans; D016212:Transforming Growth Factor beta