Cryptochromes Mediate Intrinsic Photomechanical Transduction in Avian Iris and Somatic Striated Muscle

Abstract

Irises isolated from the eyes of diverse species constrict when exposed to light. Depending on species this intrinsic photomechanical transduction response (PMTR) requires either melanopsin or cryptochrome (CRY) photopigment proteins, generated by their respective association with retinoid or flavin adenine dinucleotide (FAD) chromophores. Although developmentally relevant circadian rhythms are also synchronized and reset by these same proteins, the cell type, mechanism, and specificity of photomechanical transduction (PMT) and its relationship to circadian processes remain poorly understood. Here we show that PMTRs consistent with CRY activation by 430 nm blue light occur in developing chicken iris striated muscle, identify relevant mechanisms, and demonstrate that similar PMTRs occur in striated iris and pectoral muscle fibers, prevented in both cases by knocking down CRY gene transcript levels. Supporting CRY activation, iris PMTRs were reduced by inhibiting flavin reductase, but unaffected by melanopsin antagonism. The largest iris PMTRs paralleled the developmental predominance of striated over smooth muscle fibers, and shared their requirement for extracellular Ca 2+ influx and release of intracellular Ca 2+. Photostimulation of identified striated myotubes maintained in dissociated culture revealed the cellular and molecular bases of PMT. Myotubes in iris cell cultures responded to 435 nm light with increased intracellular Ca 2+ and contractions, mimicking iris PMTRs and their spectral sensitivity. Interestingly PMTRs featuring contractions and requiring extracellular Ca 2+ influx and release of intracellular Ca 2+ were also displayed by striated myotubes derived from pectoral muscle. Consistent with these findings, cytosolic CRY1 and CRY2 proteins were detected in both iris and pectoral myotubes, and knocking down myotube CRY1/CRY2 gene transcript levels specifically blocked PMTRs in both cases. Thus CRY-mediated PMT is not unique to iris, but instead reflects a more general feature of developing striated muscle fibers. Because CRYs are core timing components of circadian clocks and CRY2 is critical for circadian regulation of myogenic differentiation CRY-mediated PMT may interact with cell autonomous clocks to influence the progression of striated muscle development.

Use of a Self-Delivering Anti-CCL3 FANA Oligonucleotide as an Innovative Approach to Target Inflammation after Spinal Cord Injury

“…One of the most important modification to the biological function of FANA ASO molecules is their ability to penetrate cells without the necessity of delivery vehicles required in transfection approaches. Our results revealed that FANA ASO molecules targeting CCL3 can indeed penetrate BMDMs in gymnotic fashion, as previously described for other cell types in vitro (Baby et al, 2020;Margiotta and Howard, 2020;Schmidt et al, 2019;Smaldone et al, 2019;Suwanmanee et al, 2019;Takahashi et al, 2019). We also demonstrated the successful suppression of CCL3 expression in BMDMs by CCL3 specific FANA ASOs.…”

Harmonizing Magnetic Mitohormetic Regenerative Strategies: Developmental Implications of a Calcium–Mitochondrial Axis Invoked by Magnetic Field Exposure

“…Therefore, key components of the termite magnetic orientation system are expressed in muscle. Moreover, TRPC1 is implicated in store-operated calcium entry (SOCE) [88], and evidence of a SOCE-and flavin-dependent, redox-sensitive, photomechanical transduction process requiring the participation of Cry2 during muscle development has recently emerged [165]. Finally, the genetic knockdown of the entire TRPC family was shown to alter cryptochrome-mediated circadian ("crycadian") rhythm, cytokine, and metabolic functions [166], congruent with the cellular functions that have been correlated with TRPC1 expression.…”

“…TRPC1 has been directly implicated in phototransduction in diverse species and tissues [97][98][99]. Moreover, both magnetoreception [10] and photomechanical transduction [165] can be antagonized by the TRPC channel blocker, 2-APB, or other forms of inhibiting extracellular calcium entry, drawing provocative parallels. TRPC1 may hence comprise part of a magnetic signaling complex, analogous to Orco (olfactory sensory receptor channel) in termites [159], which in collaboration with Cry2 and potentially other molecular partners confers field directionally specific developmental responses.…”

Basic Principles of RNA Interference: Nucleic Acid Types and In Vitro Intracellular Delivery Methods

“…As ASO design is complicated, most researchers purchase them from manufacturers. Lacking knowledge of the exact sequence or chemistry, it is much more difficult to interpret nonspecific signals and optimize design [ 129 , 130 , 131 ]. Nevertheless, there are already approaches and studies using ASOs in therapeutic contexts to treat viral diseases, genetic alterations, cancer, chronic inflammation, and COVID-19 [ 130 , 132 , 133 ].…”