Miswired Proprioception in Amyotrophic Lateral Sclerosis in Relation to Pain Sensation (and in Delayed Onset Muscle Soreness)—Is Piezo2 Channelopathy a Principal Transcription Activator in Proprioceptive Terminals Besides Being the Potential Primary Damage?

Abstract

Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative multisystem disease, with an unknown pathomechanism, resulting in progressive motoneuron loss. In 90–95% of cases, ALS is sporadic, but close to 10% of ALS is familial with inherited gene mutations from family members. Recently, a non-contact dying-back injury mechanism theory of ALS postulated that irreversible intrafusal proprioceptive terminal degeneration induces the non-resolving progressive impairment of the proprioceptive circuitry, leading to motoneuron loss, progressive overloading and depletion of the central nervous system, and eventually to death. The current manuscript proposes that irreversible Piezo2 channelopathy of this proprioceptive terminal degeneration induces constantly activated and dysregulated transcription process in ALS, providing access to underlying pathogenic gene variants and letting the cell-type-specific noncoding DNA mutations become more apparent. This opinion piece proposes that ALS genes are associated with the Piezo2 channelopathy mechanism both downstream and upstream, and their mutations, along with the aging process, could explain the non-contact dying-back injury mechanism theory of ALS. Moreover, irreversible microinjury of the Piezo2 ion channel could be the primary damage or the root cause of death in ALS. Finally, the current manuscript also depicts the pathomechanism as to why ALS is considered a painless disease.