B-10

Amino Acid Sequence

3D Structure (/structures/AF-Q9UM73-F1-model_v6.cif)

Function

Neuronal receptor tyrosine kinase that is essentially and transiently expressed in specific regions of the central and peripheral nervous systems and plays an important role in the genesis and differentiation of the nervous system. Also acts as a key thinness protein involved in the resistance to weight gain: in hypothalamic neurons, controls energy expenditure acting as a negative regulator of white adipose tissue lipolysis and sympathetic tone to fine-tune energy homeostasis. Following activation by ALKAL2 ligand at the cell surface, transduces an extracellular signal into an intracellular response. In contrast, ALKAL1 is not a potent physiological ligand for ALK. Ligand-binding to the extracellular domain induces tyrosine kinase activation, leading to activation of the mitogen-activated protein kinase (MAPK) pathway. Phosphorylates almost exclusively at the first tyrosine of the Y-x-x-x-Y-Y motif. Induces tyrosine phosphorylation of CBL, FRS2, IRS1 and SHC1, as well as of the MAP kinases MAPK1/ERK2 and MAPK3/ERK1. ALK activation may also be regulated by pleiotrophin (PTN) and midkine (MDK). PTN-binding induces MAPK pathway activation, which is important for the anti-apoptotic signaling of PTN and regulation of cell proliferation. MDK-binding induces phosphorylation of the ALK target insulin receptor substrate (IRS1), activates mitogen-activated protein kinases (MAPKs) and PI3-kinase, resulting also in cell proliferation induction. Drives NF-kappa-B activation, probably through IRS1 and the activation of the AKT serine/threonine kinase. Recruitment of IRS1 to activated ALK and the activation of NF-kappa-B are essential for the autocrine growth and survival signaling of MDK. May function as regulator of gastric epithelial differentiation.

Mechanism

The ubiquitin-proteasome pathway (UPP) constitutes the principal pathway for protein degradation in eukaryotic cells, mediating the breakdown of target proteins through ubiquitin tagging and subsequent proteasomal degradation. In an ATP-dependent manner, the ubiquitin-activating enzyme (E1) activates ubiquitin (Ub) and conjugates it to a ubiquitin-conjugating enzyme (E2). E3 ligase subsequently catalyzes the transfer of Ub to the target protein, leading to the formation of a polyubiquitin chain that completes the ubiquitination mark. The 19S regulatory particle of the 26S proteasome recognizes this ubiquitination signal and, after deubiquitination, mediates the ATP-dependent delivery of the substrate into the 20S proteasome for degradation.

Description

o elucidate the underlying degradation mechanism of B-7 and B-10, we investigated their dependence on cellular degradation pathways. H3122 cells were pretreated for 4 h with either the proteasome inhibitor MG132 (2 μM) or the autophagy/lysosome inhibitor chloroquine (100 μM) followed by co-treatment with B-10 (2 μM) for 24 h. As shown in Fig. 4D, ALK degradation by B-10 was markedly suppressed by MG132, but remained largely unaffected by chloroquine. These findings indi cated that ALK degradation induced by B-10 was primarily mediated by the proteasomal pathway.

Description

The antiproliferative capacity of the B-series compounds was first assessed in H3122 cells harboring the EML4–ALK fusion protein, using Brigatinib as positive control. Notably, B-7 was the most potent compound in the B-series (IC50 = 68.98 nM), followed by B-10 (IC50 = 97.77 nM) and B-6 (IC50 = 162.34 nM);The inhibitory activities of B-6, B-7, B-9, and B-10 against the ALK were evaluated with Brigatinib as a positive control. As summarized shown in Table 2 and Fig. S2 (the corresponding inhibition curves), all selected compounds maintained potent inhibition of ALK, with IC50 values of 1.24 nM (B-6), 0.74 nM (B-7), 0.92 nM (B-9), and 1.20 nM (B10).

Description

The inhibitory activities of B-6, B-7, B-9, and B-10 against the ALK were evaluated with Brigatinib as a positive control. As summarized shown in Table 2 and Fig. S2 (the corresponding inhibition curves), all selected compounds maintained potent inhibition of ALK, with IC50 values of 1.24 nM (B-6), 0.74 nM (B-7), 0.92 nM (B-9), and 1.20 nM (B10).