Activation of spinocerebellar neurons by adequate exteroceptive and proprioceptive stimulation

ABSTRACT Ubiquitin conjugation typically requires three classes of enzyme: E1, E2, and E3. A fourth type of enzyme (E4), however, was recently shown to be required for the degradation of certain types of substrate in yeast. We previously identified UFD2a (also known as E4B) as an E4 in mammals. UFD2a is exclusively expressed in cardiac muscle during mouse embryonic development, but it is abundant in neurons of adult mice and is implicated in the pathogenesis of neurodegenerative disease. The precise physiological function of this enzyme has remained largely unknown, however. Here, we show that mice lacking UFD2a die in utero, manifesting marked apoptosis in the developing heart. Polyubiquitylation activity for an E4 substrate was greatly reduced in Ufd2a −/− mouse embryonic fibroblasts. Furthermore, Ufd2a +/− mice displayed axonal dystrophy in the nucleus gracilis, as well as degeneration of Purkinje cells accompanied by endoplasmic reticulum stress. These animals also developed a neurological disorder. UFD2a thus appears to be essential for the development of cardiac muscle, as well as for the protection of spinocerebellar neurons from degeneration induced by endoplasmic reticulum stress.

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On the Magnus-Kleyn reflexes in organic lesions of the central nervous system

Kazan medical journal ◽

10.17816/kazmj77112 ◽

1927 ◽

Vol 23 (6-7) ◽

pp. 676-685

Author(s):

L. I. Omorokov

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Proprioceptive Stimulation ◽

The Central Nervous System ◽

Head Neck ◽

Organic Lesions

The works of R. Magnus and his students in Utrecht discovered and developed the doctrine of special reflexes accompanied by a change in tone depending on the position of the head, neck, torso and members in space. These reflexes, which are called tonic, labyrinth and cervical reflexes, are caused by proprioceptive stimulation coming either from the muscles of the neck (Brondgeest and Shrington) or from the labyrinth (Ewald).

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Processing of proprioceptive signals by ascending interneurones in the terminal abdominal ganglion of the crayfish

Journal of Experimental Biology ◽

10.1242/jeb.202.21.2975 ◽

1999 ◽

Vol 202 (21) ◽

pp. 2975-2984

Author(s):

H. Aonuma ◽

P.L. Newland ◽

T. Nagayama

Keyword(s):

Action Potentials ◽

Chordotonal Organ ◽

Simultaneous Application ◽

Proprioceptive Input ◽

Proprioceptive Stimulation ◽

Motor Neurones ◽

Tail Flip ◽

Local Circuits ◽

Proprioceptive Inputs ◽

Subthreshold Level

Intersegmental interneurones are crucial for the appropriate coordination of the activity of local circuits located in different body segments. We have analysed the synaptic inputs to ascending intersegmental interneurones from a proprioceptor in the tailfan of the crayfish. Twenty identified interneurones responded during stimulation of the exopodite-endopodite chordotonal organ. Of these 20 interneurones, three were excited phaso-tonically, nine were excited phasically and eight were inhibited. All received convergent exteroceptive inputs from water-motion- or touch-sensitive hairs on the uropods. The effects of simultaneous exteroceptive and proprioceptive stimulation depended upon the identity of an interneurone. For interneurones that were inhibited by proprioceptive stimulation, suprathreshold exteroceptive responses were reduced to a subthreshold level by simultaneous proprioceptive stimulation. In contrast, for interneurones that were excited by proprioceptive stimulation, the simultaneous application of subthreshold proprioceptive and exteroceptive stimulation elicited action potentials. Two of the interneurones that receive proprioceptive input (NE-1 and RC-8) are known to be presynaptic to giant interneurones that mediate and coordinate the tail-flip. Many of the other interneurones that receive proprioceptive inputs in the tailfan are known to excite abdominal extensor motor neurones. Thus, proprioceptive input to these intersegmental interneurones could serve two roles: first, to extend the abdomen during postural movements or prior to escape and, second, to drive the tail-flip escape response.

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