Myosin X (MYO10) was recently reported to promote tumour invasion by transporting integrins to filopodial tips in breast cancer. However, the role of MYO10 in tumours remains poorly defined. Here, we report that MYO10 is required in invadopodia to mediate invasive growth and extracellular matrix degradation, which depends on the binding of MYO10’s pleckstrin homology domain to PtdIns(3,4,5)P3. The expression of MYO10 and its associations with clinicopathological and biological factors were examined in breast cancer cells and breast cancer specimens (n=120). Cell migration and invasion were investigated after the silencing of MYO10. The ability of cells to form invadopodia was studied using a fluorescein isothiocyanate-conjugated gelatin degradation assay. A mouse model was established to study tumour invasive growth and metastasis in vivo. Elevated MYO10 levels were correlated with oestrogen receptor status, progesterone receptor status, poor differentiation, and lymph node metastasis. Silencing MYO10 reduced cell migration and invasion. Invadopodia were responsible for MYO10’s role in promoting invasion. Furthermore, decreased invasive growth and lung metastasis were observed in the MYO10-silenced nude mouse model. Our findings suggest that elevated MYO10 expression increases the aggressiveness of breast cancer; this effect is dependent on the involvement of MYO10 in invadopodial formation.

Macroautophagy/autophagy is an evolutionarily conserved pathway that is required for cellular homeostasis, growth and survival. The lysosome plays an essential role in autophagy regulation. For example, the activity of MTORC1, a master regulator of autophagy, is regulated by nutrients within the lysosome. Starvation inhibits MTORC1 causing autophagy induction. Given that MTORC1 is critical for protein synthesis and cellular homeostasis, a feedback regulatory mechanism must exist to restore MTORC1 during starvation. However, the molecular mechanism underlying this feedback regulation is unclear. In this study, we report that starvation activates the lysosomal Ca²⁺ release channel MCOLN1 (mucolipin 1) by relieving MTORC1's inhibition of the channel. Activated MCOLN1 in turn facilitates MTORC1 activity that requires CALM (calmodulin). Moreover, both MCOLN1 and CALM are necessary for MTORC1 reactivation during prolonged starvation. Our data suggest that lysosomal Ca²⁺ signaling is an essential component of the canonical MTORC1-dependent autophagy pathway and MCOLN1 provides a negative feedback regulation of MTORC1 to prevent excessive loss of MTORC1 function during starvation. The feedback regulation may be important for maintaining cellular homeostasis during starvation, as well as many other stressful or disease conditions.

Neogenin, a DCC (deleted in colorectal cancer) family receptor, is highly expressed in neural stem cells (NSCs). However, its function in NSCs remains to be explored. Here we providein vitroandin vivoevidence for neogenin's function in NSCs to promote neocortical astrogliogenesis, but not self-renewal or neural differentiation. Mechanistically, neogenin in neocortical NSCs was required for BMP2 activation of YAP (yes associated protein). The active/nuclear YAP stabilized phospho-Smad1/5/8 and was necessary for BMP2 induction of astrocytic differentiation. Deletion ofyapin mouse neocortical NSCs caused a similar deficit in neocortical astrogliogenesis as that inneogeninmutant mice. Expression of YAP inneogeninmutant NSCs diminished the astrocytic differentiation deficit in response to BMP2. Together, these results reveal an unrecognized function of neogenin in increasing neocortical astrogliogenesis, and identify a pathway of BMP2-neogenin-YAP-Smad1 for astrocytic differentiation in developing mouse neocortex.SIGNIFICANCE STATEMENTAstrocytes, a major type of glial cells in the brain, play important roles in modulating synaptic transmission and information processing, and maintaining CNS homeostasis. The abnormal astrocytic differentiation during development contributes to dysfunctions of synaptic plasticity and neuropsychological disorders. Here we provide evidence for neogenin's function in regulation of the neocortical astrocyte differentiation during mouse brain development. We also provide evidence for the necessity of neogenin in BMP2/Smad1-induced astrocyte differentiation through YAP. Thus, our findings identify an unrecognized function of neogenin in mouse neocortical astrocyte differentiation, and suggest a signaling pathway, BMP2-neogenin-YAP-Smad1, underlying astrogliogenesis in developing mouse neocortex.

Dendritic spine development is crucial for the establishment of excitatory synaptic connectivity and functional neural circuits. Alterations in spine morphology and density have been associated with multiple neurological disorders. Autism candidate gene disconnected-interacting protein homolog 2 A (DIP2A) is known to be involved in acetylated coenzyme A (Ac-CoA) synthesis and is primarily expressed in the brain regions with abundant pyramidal neurons. However, the role of DIP2A in the brain remains largely unknown. In this study, we found that deletion of Dip2a in mice induced defects in spine morphogenesis along with thin postsynaptic density (PSD), and reduced synaptic transmission of pyramidal neurons. We further identified that DIP2A interacted with cortactin, an activity-dependent spine remodeling protein. The binding activity of DIP2A-PXXP motifs (P, proline; X, any residue) with the cortactin-Src homology 3 (SH3) domain was critical for maintaining the level of acetylated cortactin. Furthermore, Dip2a knockout (KO) mice exhibited autism-like behaviors, including excessive repetitive behaviors and defects in social novelty. Importantly, acetylation mimetic cortactin restored the impaired synaptic transmission and ameliorated repetitive behaviors in these mice. Altogether, our findings establish an initial link between DIP2A gene variations in autism spectrum disorder (ASD) and highlight the contribution of synaptic protein acetylation to synaptic processing.