Mechanotransduction Mechanisms of Hypertrophy and Performance with Resistance Exercise
Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse in The Routledge Handbook on Biochemistry of Exercise, 2020
This chapter will take a close look at the rapidly emerging field of mechanotransduction in skeletal muscle. The term “transduction” refers to the conversion of a message or energy from one form to another. Since the function of skeletal muscle is specifically to contract and develop force, how does the muscle cell convert these mechanical forces to an intracellular signal? And how might these signals influence the muscle phenotype, size, and performance? In this chapter, we will specifically examine the muscle forces that are developed during resistance exercise. As you will soon read, we will first present an overview of what is currently known about mechanotransduction in skeletal muscle. This is followed by a brief presentation of what resistance exercise is in its many forms, followed by a description of what current research tells us about how resistance exercise uses mechanotransduction in the adaptation process. Finally, we will attempt to integrate the mechanotransduction system with other well-studied physiological systems that help regulate the activity of skeletal muscle. It is imperative that we not examine mechanotransduction in isolation, especially since the successful performance of skeletal muscle is so dependent on numerous physiological systems working in highly organized synchrony with each other.
Physiology of excitable cells
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2015
Sensory receptors include exteroreceptors, interoreceptors and proprioceptors. In general, sensory transduction is accomplished by the production of a receptor potential and encode modality, spatial localization, intensity, duration and frequency of stimuli. Sensory receptors may show accommodation. Muscle spindles are sensory receptors in skeletal muscles that lie parallel to the regular extrafusal muscle fibres. They consist of nuclear bag and nuclear chain intrafusal fibres. Ia afferent fibres form primary nerve endings on both nuclear bag and chain fibres. Group II afferent fibres form a secondary ending, which is found chiefly on the nuclear chain fibres. Primary endings detect static (change in length) and dynamic (rate of change in muscle length) changes in muscle, whereas secondary endings detect only static responses. The γ efferent system controls the sensitivity of the muscle spindle. The muscle spindles also dampen jerky or oscillatory muscle contractions. The Golgi tendon organs, located in the tendons of the muscles, are arranged in series with the skeletal muscle. They are supplied by IIb afferent fibres and are stimulated by both stretch and contraction of the muscle. The stretch reflex includes a monosynaptic excitatory pathway from muscle spindle afferent (Ia and II) fibres to the α motor neurons to the same and synergistic muscle and a disynaptic inhibitory pathway to the motor neurons of the antagonist muscles.
Disorders of Growth and Differentiation
Jeremy R. Jass in Understanding Pathology, 2020
Cell division must be coordinated with the needs of tissue and indeed the entire organism. This is achieved by means of hormones and growth factors, hormone and growth factor receptors arranged upon the cell membrane, signal transduction pathways (transferring messages from cell membrane to nucleus) and nuclear proteins (to prepare the cell for division). The function of signal transduction pathways is to bring about amplification and integration of the various messages received by the array of receptors upon the cell surface and so relay an unambiguous message to the nucleus. These cascade systems operate through the enzymatic conversion of an inactive precursor to an active enzyme. This is achieved by a surprisingly limited number of mechanisms (Fig. 18). Some of the genes coding for growth factors, receptors, cell signalling molecules or nuclear proteins that drive mitogenesis are called proto-oncogenes. This is because mutated versions (oncogenes; see Chapter 23) have been shown to drive cell proliferation in neoplasms (Table 4).
There and back again: a dendrimer’s tale
Published in Drug and Chemical Toxicology, 2022
Barbara Ziemba, Maciej Borowiec, Ida Franiak-Pietryga
The signal transduction pathway is a cascade of biochemical reactions involving the transmission of molecular signals from a cell exterior to its interior. Signals received by cells must be transmitted effectively to the target molecules to assure an appropriate response. Signaling pathway dysregulation can influence cell growth, proliferation, division, metabolism, or survival and lead to disease development. Dendrimers, as nanoparticles, may easily disrupt signal transduction by affecting any element of the pathway. Such activity may have adverse effects, but also advantages, e.g., in cancer or metabolic diseases therapy. Therefore, findings on dendrimers’ biological effects in terms of their interactions with key cellular signal transduction pathways may have important clinical implications.
An update on gene therapy for lysosomal storage disorders
Published in Expert Opinion on Biological Therapy, 2019
Murtaza S. Nagree, Simone Scalia, William M. McKillop, Jeffrey A. Medin
Standard VSV-G-pseudotyped recombinant LV displays a wide tropism [30]. Thus, systemic LV injection with VSV-G-pseudotyped LV results in widespread transduction and minimal tissue specificity [30]. However, transgene expression can still be restricted by employing tissue-specific promoters [58]. Cell type-specific transduction can also be achieved by modifying the LV pseudotype [59]. Systemically delivered LV transduction efficiency is largely a function of the bolus size (amount and concentration during injection) of the vector and the site of injection. For example, injection into the hepatic portal vein should allow more selective transduction of the liver [60]. LV tends to not permeate well into parenchymal components of tissues, which may be due to preferential transduction of, or phagocytosis by, Kupffer or similar cells [61].
C. elegans: a sensible model for sensory biology
Published in Journal of Neurogenetics, 2020
Adam J. Iliff, X.Z. Shawn Xu
Sensory neurobiology exists at the interface between biology, chemistry and physics. Our sensory processes mediate our interaction with the physical world. It is incredible that life has evolved to detect a vast array of forces and molecules present in our universe. Organisms as seemingly disparate as nematodes and humans have much in common in regard to their sensory processes. The relationship of an organism with its external and internal environments arguably begins with the sensory inputs and ends with behavioral output. Perception occurs via sensory neurons that activate in response to specific stimuli. These cues act upon sensory transduction machinery expressed by the sensory neuron itself or in specialized structures that communicate with the sensory neuron. Some of these sensory structures have evolved into large complex organs, such as the mammalian eye. However, such complexity incorporating large numbers of cells is not required for a sophisticated sensory system. Even a tiny one millimeter long organism with a compact nervous system of only 302 neurons can detect a surprisingly vast and varied array of physical stimuli, such as mechanical forces, chemicals, light, temperature, humidity and electromagnetic fields (Figure 1). The evolution of these sensory modalities confers numerous benefits to survival, including the ability to find food and mates and to avoid hazard.
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