The non-canonical interaction between calmodulin and calcineurin contributes to the differential regulation of plant-derived calmodulins on calcineurin.

Calmodulin (CaM) is an important Ca2+ signaling hub that regulates many protein signaling pathways. In recent years, several CaM homologs expressed in plants have been shown to regulate mammalian targets and they are attractive for gene therapy. However, the molecular basis of how the CaM homologs mutations impact target activation is unclear, which limits efforts to engineer their functional properties. To understand these mechanisms, we examined two CaM isoforms found in soybean plants that differentially regulate a mammalian target, calcineurin (CaN). These CaM isofroms, sCaM-1 and sCaM-4 share >90% and ≈78% identity with the mammalian CaM (mCaM), respectively, activate CaN with comparable or reduced activity relative to mCaM. We used molecular simulations and experimental assays to probe whether calcium and protein-protein binding interactions are altered in plant CaMs relative to mCaM as a basis for differential CaN regulations. We found that the two sCaMs' calcium binding properties such as coordination and affinity are comparable to mCaM. Further, the binding of CaM to the CaM binding region (CaMBR) in CaN is also comparable among the three CaMs, as evidenced by calculated binding free energies and experimental measured EC50 [CaM]. However, mCaM and sCaM-1 exhibited stronger binding with a secondary region of CaN's regulatory domain that is weakened for sCaM-4. This secondary interaction is likely to affect the turnover rate (kcat) of CaN based on our modeling of enzyme activity and is consistent with our experimental data. Together, our data show how plant-derived CaM variants can alter target activation through interactions beyond calcium binding and canonical CaMBR binding, which may extend beyond the mammalian CaN target.

Near-Infrared Photoactivatable Immunomodulatory Nanoparticles for Combinational Immunotherapy of Cancer

As a promising treatment option for cancer, immunotherapy can eliminate local and distant metastatic tumors and even prevent recurrence through boosting the body’s immune system. However, immunotherapy often encounters the issues of limited therapeutic efficacy and severe immune-related adverse events in clinical practices, which should be mainly due to the non-specific accumulations of immunotherapeutic agents. Activatable immunomodulatory agents that are responsive to endogenous stimuli in tumor microenvironment can afford controlled immunotherapeutic actions, while they still face certain extent of off-target activation. Since light has the advantages of noninvasiveness, simple controllability and high spatio-temporal selectivity, therapeutic agents that can be activated by light, particularly near-infrared (NIR) light with minimal phototoxicity and strong tissue penetrating ability have been programmed for cancer treatment. In this mini review, we summarize the recent progress of NIR photoactivatable immunomodulatory nanoparticles for combinational cancer immunotherapy. The rational designs, constructions and working mechanisms of NIR photoactivatable agents are first briefly introduced. The uses of immunomodulatory nanoparticles with controlled immunotherapeutic actions upon NIR photoactivation for photothermal and photodynamic combinational immunotherapy of cancer are then summarized. A conclusion and discussion of the existing challenges and further perspectives for the development and clinical translation of NIR photoactivatable immunomodulatory nanoparticles are finally given.

A MYT1L Syndrome mouse model recapitulates patient phenotypes and reveals altered brain development due to disrupted neuronal maturation

Human genetics have defined a new autism-associated syndrome caused by loss-of-function mutations in MYT1L, a transcription factor known for enabling fibroblast-to-neuron conversions. However, how MYT1L mutation causes autism, ADHD, intellectual disability, obesity, and brain anomalies is unknown. Here, we develop a mouse model of this syndrome. Physically, Myt1l haploinsufficiency causes obesity, white-matter thinning, and microcephaly in the mice, mimicking clinical phenotypes. Studies during brain development reveal disrupted gene expression, mediated in part by loss of Myt1l gene target activation, and highlight precocious neuronal differentiation as the mechanism for microcephaly. In contrast, adult studies reveal that mutation results in failure of transcriptional and chromatin maturation, echoed in disruptions in baseline physiological properties of neurons. This results in behavioral features including hyperactivity, hypotonia, and social alterations, with more severe phenotypes in males. Overall, these studies provide insight into the mechanistic underpinnings of this disorder and enable future preclinical studies.

Visual working memory load constrains language non-selective activation under task-demands

Visual world studies with bilinguals have demonstrated spontaneous cross-linguistic activations. In two experiments, we examined whether concurrent visual working memory (VWM) load constrains bilingual parallel activation during spoken word comprehension. Hindi-English bilinguals heard a spoken word in Hindi (L1) or English (L2) and saw a display containing the spoken word-referent, a phonological cohort of the spoken word’s translation and two unrelated objects. Participants completed a concurrent WM task of remembering an array of five coloured squares and judging its similarity with a test array. Participants were asked to click on the spoken word-referent in Experiment 1 but not in Experiment 2. Reduced parallel activation and enhanced target activation was observed under the load for L2 spoken words in Experiment 1 (where the task-demands were high). The findings suggest that a VWM load can constrain the spontaneous activation of an irrelevant lexicon, under certain conditions.