High impact information on activin-beta

• We conclude that the Drosophila Activin signaling pathway mediates neuronal remodeling in part by regulating EcR-B1 expression [1].
• These experiments, as well as the effects of the mRNAs on embryo phenotypes, suggest that the Xsox17 genes mediate an activin-induced endoderm differentiation pathway in animal caps and are involved in normal endoderm differentiation in embryos [2].
• Xmad1 produces ventral mesoderm, apparently transducing a signal for BMP2 and BMP4, whereas Xmad2 induces dorsal mesoderm like Vg1, activin, and nodal [3].
• In this report, we demonstrate that the Drosophila punt gene encodes atr-II, a previously described type II receptor that on its own is able to bind activin but not BMP2, a vertebrate ortholog of dpp [4].
• The TGF-beta/activin/BMP cytokine family signals through serine/threonine kinase receptors, but how the receptors transduce the signal is unknown [5].

Biological context of activin-beta

• We also show that the zygotic expression of a recently described Drosophila activin, which maps to the same interval 102 on chromosome 4 as myoglianin, is restricted to the developing central and peripheral nervous system [6].
• During head morphogenesis, Patched positively interacts with Smoothened, which leads to the activation of Activin type I receptor Baboon and stimulation of cell proliferation in the eye-antennal disc [7].

Anatomical context of activin-beta

• Our results indicate that Daw functions in a permissive manner to modulate or enable the growth cone response to other restricted guidance cues, and support a novel role for activin signaling in axon guidance [8].
• We propose that dSno functions as a switch in optic lobe development, shunting Medea from the Dpp pathway to the Activin pathway to ensure proper proliferation [9].
• These genes were subsequently tested for expression in the organizer region of blastula/gastrula-stage embryos as well as inducibility by activin [10].
• Our effort resulted in the isolation of a gene, XFKH1, that is primarily expressed in the dorsal blastopore lip of early gastrulae and is inducible by activin [10].
• Ectopic Dpp or Activin signalling resulted in overproliferation of both stem cell-like and spermatogonial-like cells in the apical region of the testis [11].

Associations of activin-beta with chemical compounds

• With the exception of the spacing of 10 cysteine residues, the extracellular domain of Atr-II is very dissimilar from those of vertebrate activin receptors, yet it binds activin with high affinity and specificity [12].
• I review these new perspectives, and analyze in detail two models, one pertaining to the propagation of activin in Xenopus embryos, the other to the interpretation of retinoic acid levels into transcription patterns by nuclear receptors [13].

Enzymatic interactions of activin-beta

• We show that dSmad2 induces activin responsive genes in Xenopus animal cap assays. dSMAD2 is phosphorylated by ATR-I and PUNT, but not by activated THICK VEINS, and translocates to the nucleus upon activation [14].

Regulatory relationships of activin-beta

• However, Atr-I binds activin efficiently when coexpressed with the distantly related Drosophila activin receptor Atr-II, with which it forms a heteromeric complex [15].

Other interactions of activin-beta

• We find that Daw initiates an activin signaling pathway via the receptors Punt and Baboon (Babo) and the signal-transducer Smad2 [8].
• RESULTS: Here we report the identification of dSmad2, a new Drosophila Smad which is most related to the activin/TGFbeta-pathway Smads, Smad2 and Smad3 [14].
• Interestingly, expression of the ecdysone receptor B1 isoform (EcR-B1) is reduced in activin pathway mutants, and restoring EcR-B1 expression significantly rescues remodeling defects [1].
• Our observations also suggest new roles for the dSmads, Med and Dad, in dActivin signaling and potential interactions between these family members [16].
• Our protocols were used to isolate cDNAs for the Drosophila activin and follistatin genes [17].

Analytical, diagnostic and therapeutic context of activin-beta

• Northern blot and RT-PCR analyses indicated that the activin beta gene is expressed in embryo, larva and adult stages of Drosophila [18].

References