Neurotrophic and Growth Factors Lecture Practice Flashcards

Comprehensive vocabulary flashcards covering neurotrophic factors (Leptin, Irisin) and the diverse Wnt signaling pathways and their physiological roles as discussed in the lecture.

Leptin

A factor released from white adipose tissue and the periphery that regulates food intake, energy expenditure, and hippocampal synaptic plasticity through its receptors ($LEPR$).

Irisin

A 12 kDa "myokine" synthesized from skeletal muscle during exercise; it is cleaved from $FNDC5$ and increases the expression of $BDNF$ in the brain.

$$FNDC5$$

The precursor protein to Irisin, expressed in the brain and induced by Leptin, which contains a Fibronectin III domain and a signal peptide.

Wnt

A secreted lipid-modified glycoprotein derived from a contraction of the Drosophila "Wingless" and "Integrase-1" genes; there are 19 such genes in the human genome.

Frizzled Receptor

A seven-transmembrane receptor that serves as the primary receptor for Wnt and can complex with co-receptors $LRP5/6$.

Canonical Pathway

Also known as the $Wnt/\beta-Catenin$ pathway; it involves the stabilization and nuclear translocation of $\beta-Catenin$ to stimulate transcription via T-Cell Factor ($TCF$).

$$\beta-transducin repeat containing protein (\beta-TRCP)$$

A protein that binds to phosphorylated $\beta-Catenin$, leading to its ubiquitylation and proteasomal breakdown under basal conditions.

Destruction Complex

A multi-protein complex including $AXIN$, $CK1$, and $GSK3\beta$ that sequentially phosphorylates $\beta-Catenin$ to signal for its degradation.

Planar Cell Polarity (PCP) Pathway

A non-canonical Wnt signaling pathway that activates $RhoA/ROCK$ and $Rac1$ to regulate the actin cytoskeleton and cell adhesion/migration without requiring $\beta-Catenin$.

$DAAM$ (Dishevelled-associated activator of morphogenesis)

A protein associated with $DVL$ in the PCP pathway that mediates the activation of $RhoA/ROCK$.

$Wnt-Ca^{2+}$ Pathway

A pathway activated by $Wnt5A$ and Frizzled through G-proteins and $PLC$, leading to increased $Ca^{2+}$, $PKC$ activity, and $NFAT$ dependent transcription.

sFRP (Secreted Frizzled-related protein)

A family of extracellular Wnt antagonists that function by binding directly to Wnt and Frizzled molecules.

Dickkopf ($Dkk$)

A selective antagonist for the canonical Wnt pathway that acts by binding to the $LRP5/6$ co-receptors.

Stem Cell Niche

A special micro-environment where pluripotent stem cells reside, maintaining proliferative potential and self-renewal through signals like Wnt.

Neurogenesis

A process within the hippocampus involving the proliferation of stem cells into mature newborn neurons; it is often decreased in depression and increased by Leptin and Wnt.

Wnt3

A Wnt protein expressed close to the subgranular zone ($SGZ$) that increases neuronal production when overexpressed in hippocampal stem cells.

Wnt2

A protein upregulated following electroshock therapy within the subgranular zone that acts as an activity-dependent regulator of growth.

Wnt7a

A target-derived signal that specifically regulates the assembly of synapses.

Rett Syndrome

An Autism Spectrum Disorder (ASD)-like disease associated with elevated Leptin levels in the absence of obesity.

$WIF-1$ (Wnt-Inhibitory factor)

An extracellular inhibitor that binds directly to Wnt to block canonical and non-canonical signaling.