Differential effects of Drosophila mastermind on asymmetric cell fate specification and neuroblast formation.
During neurogenesis in the ventral nerve cord of the Drosophila embryo, Notch signaling participates in the pathway that mediates asymmetric fate specification to daughters of secondary neuronal precursor cells. In the NB4-2 --> GMC-1 --> RP2/sib lineage, a well-studied neuronal lineage in the ventral nerve cord, Notch signaling specifies sib fate to one of the daughter cells of GMC-1. Notch mediates this process via Mastermind (Mam). Loss of function for mam, similar to loss of function for Notch, results in GMC-1 symmetrically dividing to generate two RP2 neurons. Loss of function for mam also results in a severe neurogenic phenotype. In this study, we have undertaken a functional analysis of the Mam protein. We show that while ectopic expression of a truncated Mam protein induces a dominant-negative neurogenic phenotype, it has no effect on asymmetric fate specification. This truncated Mam protein rescues the loss of asymmetric specification phenotype in mam in an allele-specific manner. We also show an interallelic complementation of loss-of-asymmetry defect. Our results suggest that Mam proteins might associate during the asymmetric specification of cell fates and that the N-terminal region of the protein plays a role in this process.
Yedvobnick
Barry
B
Department of Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Kumar
Anumeha
A
Chaudhury
Padmashree
P
Opraseuth
Jonathan
J
Mortimer
Nathan
N
Bhat
Krishna Moorthi
KM
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D019070:Cell Lineage; D004330:Drosophila / Q000196:embryology* / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004843:Epistasis, Genetic; D018507:Gene Expression Regulation, Developmental; D008565:Membrane Proteins / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D019683:Penetrance; D051880:Receptors, Notch
D029721:Drosophila Proteins; D008565:Membrane Proteins; C497759:N protein, Drosophila; D009687:Nuclear Proteins; D051880:Receptors, Notch; C085316:mam protein, Drosophila