Activin, a member of the TGF-b superfamily, controls a variety of physiological events from the cell cycle to reproductive health. Activin activates the Smad signaling pathway through ActRII/B and ALK4 receptors. The regulation of activin signaling is carried out in part by the inhibitor protein follistatin. The mechanistic details of...
Short interfering RNAs (siRNAs) and microRNAs (miRNAs) are both processed from longer, double-stranded RNA (dsRNA) presursors by a member of the Dicer (Dcr) family of proteins. siRNAs generally arise from perfectly base-paired dsRNAs, whereas miRNAs are excised from 60-70 nt pre-miRNA hairpins containing multiple bulges and mismatches within the duplexed...
A pyramidal neuron receives thousands of inputs spread throughout its dendritic tree, which it must integrate into a decision about whether or not to fire action-potential output. Since action potentials are the primary means by which these neurons communicate with their network partners, understanding this input-output relationship is critical for...
Hypoxia is a reduction in the normal level of oxygen tension and occurs during acute and chronic vascular disease, pulmonary disease, and cancer. The key transcription factor that regulates the cellular responses to hypoxia is hypoxia-inducible-factor-1 (HIF-1). Understanding how HIF-1 is regulated is fundamental for understanding the biology of tumor...
RNA interference (RNAi) is a newly discovered gene control pathway that silences gene expression in response to double-stranded RNA. This sequence-specific downregulation occurs at the level of mRNA stability, and is directed by the double-stranded RNA trigger itself. RNAi can be separated into two distinct steps; during the initiation phase,...
In the process of development of a multicellular organism, cells must make stable, binary fate decisions in response to intercellular signaling. A critical question is how weak or transient activation of signaling pathways achieves a robust and long-term switch in gene expression, and thus determines cell fate. I report that...